8.1.1
This
section of the report presents the findings of the marine ecological (including
Indo-Pacific Humpbacked Dolphins or Chinese White Dolphin, Sousa chinensis, and Finless Porpoises, Neophocaena phocaenoides) impact assessment of the construction and
operation of the Northshore Lantau Development Feasibility Study (NLDFS). The NLDFS EIA will comprise Schedule 3 level
coverage of the cumulative environmental impacts arising from all of the
proposed developments in Northeast Lantau and will broadly cover the findings
of the EIA for the Theme Park and its associated developments, the Chok Kwo Wan
Link Road is assessed in detail and the Route 10 EIA is included to assess
cumulative habitat loss. Baseline
information on the potentially affected existing marine ecological resources
and the findings of various field surveys conducted for the assessment are
presented and evaluated.
8.1.2
The
objectives of the marine ecological assessment are as follows:
·
to establish the ecological importance of the
habitats affected by the works associated with the construction and operation
of the NLDFS and associated developments;
·
to identify marine ecological sensitive
receivers;
·
to assess the scale of possible marine
ecological impacts from the proposed Projects;
·
to highlight any insurmountable impacts to
marine ecological resources arising from the proposed Projects;
·
to identify any necessary mitigation measures
and evaluate residual impacts; and
·
to assess the need for a marine ecological
monitoring and audit programme.
8.2.1
The
criteria for evaluating marine ecological impacts are laid out in the EIAO TM. Annex 16 sets out the
general approach and methodology for assessment of marine ecological impacts
arising from a project or proposal.
This assessment allows a complete and objective identification,
prediction and evaluation of the potential marine ecological impacts. Annex
8 recommends the criteria that can be used for evaluating marine ecological
impacts.
8.2.2
Other
legislation which apply to marine species includes:
·
The
Wild Animals Protection Ordinance (Cap. 170) 1980
which protects all cetaceans and sea turtles.
8.3.1
This Study
Area for the Marine Ecology Impact Assessment is presented on Figure 8.2a and is the same as that used
for the Fisheries Impact Assessment (Section
9). Included in the area are parts
of the North Western and Western Buffer Water Control Zones (WCZs). On the basis of preliminary information from
the water quality assessment, perturbations to water quality, and thus indirect
impacts to marine ecology, are unlikely to extend outside this area. Consequently, this assessment of impacts has
focussed on the marine ecological resources of this area.
Summary
of Marine Ecology Baseline Conditions
8.3.2
The
availability of literature on the marine ecology of the Study Area is
variable. As with the majority of Hong
Kong it appears that certain ecological components have been comprehensively
studied whereas others have not. A
detailed review of literature is presented in full in Annex F. Due to the limited
literature available for some components of the marine ecosystem, field surveys
were considered necessary to fill the information gaps identified and enable a
complete and robust assessment of impacts to marine ecology to be
performed. The findings of the field
surveys are also presented in Annex F.
8.3.3
The
following presents a summary of the literature review and field surveys
conducted for this EIA and detailed in full in Annex F.
Soft
Substratum Habitats
8.3.4
Various
benthic studies have been undertaken at locations within or close to the Study
Area. Findings from the majority of
these studies were that the benthos of the seabed in the vicinity of Study Area
was dominated by polychaetes and characterised by similar or lower species
diversity and species biomass than other areas in Hong Kong.
8.3.5
Surveys
conducted for this Study in Penny’s Bay concluded that the assemblages were of
a higher abundance than surrounding areas.
However, in context with those assemblages in sediments around Hong
Kong, the infaunal assemblages of Penny’s Bay can be considered to be
similar. The assemblages were dominated
by polychaetes and all the species recorded occur frequently in Hong Kong and
no rare species were observed.
Intertidal Habitats
8.3.6
The natural
shorelines within the Study Area consisted mainly of large, hard rocky or
boulder shores, such as those at Kwai Shek, Tso Wan, Fa Peng, Pa Tau Kwu and
Sze Pak. The rocky shores supported
assemblages typical of other semi-exposed rocky shores in Hong Kong and were
thus classified as of medium ecological value.
Small sandy or cobble beaches are observed in such bay areas as Yam Tsai
Wan and Luk Keng Bay on North of Lantau.
Soft sandy/cobble shores are also located along the east coast of the
Tsing Chau Tsai headland, including Kwai Shek, Tso Wan, Fa Peng and Pa Tau
Kwu. The sandy beaches were observed as
supporting assemblages of low diversity and abundance. Hence these shores were assigned a low
ecological value rating. A small
mangrove (about 0.5 ha) is present at Luk Keng at the entrance of Yam O Bay. The seaward side of the mangrove is lined
with a mud flat. Mangroves and mud
flats are generally regarded as habitats of high ecological value, however, due
to the small size of these habitats and the disturbance associated with the
logging works in Yam O the habitats are said to be of low ecological
value.
Artificial Seawalls
8.3.7
The
majority of the coastal areas on North Lantau, ie from Siu Ho Wan to Yam Tsai
Wan and from Yam O Tuk to To Kau Wan, have been reclaimed and replaced by
sloping artificial seawalls. The east
coast of Penny's Bay from Chok Ko Wan to Wan Tuk has also been reclaimed and
lined with vertical artificial seawalls.
Few surveys have been conducted on the colonization of organisms on
artificial seawalls in Hong Kong, however, fouling organisms have been
anecdotally recorded as common on artificial seawalls, wharf files and other
marine structures()()()(). Various species of algae, coelenterates,
ascidians, bryozoans, sponges, crustaceans, molluscs and polychaetes are also
commonly observed on these artificial structures. Therefore, it can be presumed that species commonly found on
these surfaces in Hong Kong waters will be found on the artificial seawalls of
the established complexes at north Lantau and Penny's Bay. On the subtidal portions of artificial
seawalls corals have been reported to colonise the habitats. An example of this is the High Island Dam in
the eastern waters of Hong Kong which supports high percentage cover of the
rare coral Acropora on the dolosse
block sloping seawalls. It is known in
Hong Kong that depending on the location of the artificial seawalls, and the
prevailing environmental conditions, especially with reference to water
quality, that the habitats have the potential to support high ecological value
assemblages. Due to the relatively
recent construction of the artificial seawalls at Yam O (1997) and the vertical
nature of those at Penny’s Bay, it is
unlikely that at present the assemblages are of high ecological value but the
potential is noted. It should be noted
that the subtidal portions of vertical seawalls do not offer ideal habitat for
coral colonisation unlike sloping seawalls which provide a more complex habitat
and better surface for settlement of marine invertebrates.
Hard Substratum Habitats
8.3.8
Dive
surveys conducted within Penny’s Bay revealed that the assemblages are composed
of a shallow, thin veneer of common hard coral species. Percent live coral cover is generally low,
however, the inner part of the bay would appear to still support a relatively
healthy, simple coral community. The
findings are of some significance as the presence of scleractinian (reef
building) corals in Penny’s Bay extends the known local geographic range for
local hard corals. Given the presence
of hard corals in Penny’s Bay, it has been assumed that the nearby coasts at
Sze Pak, Pa Tau Kwu and Fa Peng support similar assemblages. This assumption may be overly conservative
as these sites likely support corals of lower density and diversity in view
that they are exposed to higher current speeds and seabed scour than the more
sheltered habitat of Penny’s Bay.
Nevertheless, it does allow for a precautionary approach to be taken
when assessing impacts. Hard coral
assemblages have also been reported from Kau Yi Chau which is in proximity to
the reclamation area. However as
discussed in Annex F the assemblages
at Kau Yi Chau are neither as diverse or abundant as those in Penny’s Bay and
have, therefore, been classified as of medium ecological value. Although rocky shores are present at Kwai
Shek and Tso Wan they are not considered habitats that will support hard corals
due to the high current speeds along this coastline associated with the Kap
Shui Mun Channel (greater than 1.25 m s-1 see Figure D2o in Annex D2 of
the Water Quality Assessment).
Marine Mammals
8.3.9
The
Indo-Pacific Humpbacked Dolphin, Sousa
chinensis, and the Finless Porpoise, Neophocaena
phocaenoides, are the only species of marine mammal regularly sighted in
Hong Kong waters. As sightings of Neophocaena phocaenoides have mainly
been in southern waters of Hong Kong and no records have been reported within
or close to the Study Area this species is not under threat from impacts due to
the proposed Projects. The population
of Sousa chinensis is reported to be
centred around the Pearl River Estuary and Hong Kong waters are thought to
represent the eastern portion of its range.
North Lantau represents the major area of distribution of dolphins in
Hong Kong waters, and is the only place in Hong Kong where dolphins are seen
year round. Findings of work conducted
by Dr Tom Jefferson of the Ocean Park Conservation Foundation indicate that the
abundance of the dolphin is low in Northeast and East Lantau and that they use
the areas seasonally in winter. Northeast and East Lantau are not thought to
represent a critical habitat for this dolphin species.
8.3.10
The
ecological characteristics of the different habitat types within the Study Area
have been compared with habitats in other areas of Hong Kong in order to
establish their ecological importance (Annex
F).
Ecological
Importance
8.3.11
According
to the EIAO TM Annex 8, the ecological value/importance of a habitat can be
evaluated using the following criteria:
|
·
Naturalness
|
·
Ecological Linkage
|
|
·
Size
|
·
Potential value
|
|
·
Diversity
|
·
Nursery Ground
|
|
·
Rarity
|
·
Age
|
|
·
Re-creatability
|
·
Abundance
|
8.3.12
The
criteria listed above have been applied to the information gathered and/or
reviewed on the marine ecology of the habitats within the Study Area in order
to determine the ecological value. The
application of these criteria has led the habitats to be classified as
presented in Table 8.3a. Complete details of how each habitat was
evaluated against the criteria presented above are presented in Annex F. Only habitats where permanent or temporary impacts are expected
to occur through either direct impact associated with habitat loss or indirect
impacts through perturbations to water quality parameters have been evaluated. Information on the extent and severity of
water quality impact are presented in the water quality impact assessment (see Section 5).
Table
8.3a - Summary of Ecological Value of
Assemblages Present on the Different Habitat Types in the Study Area
|
Assemblage Type
|
Low
|
Medium
|
High
|
|
Sandy
Shores
|
*
|
|
|
|
Mangrove
(Luk Keng)
|
*
|
|
|
|
Intertidal
Mud Flat (Yam O Wan)
|
*
|
|
|
|
Intertidal
Rocky Shores
|
|
*
|
|
|
Subtidal
Hard Surface (Sze Pak, Fa Peng & Pa Tau Kwu)
|
|
|
*
|
|
Subtidal
Hard Surface (Kau Yi Chau)
|
|
*
|
|
|
Subtidal
Soft Benthos
|
*
|
|
|
|
Artificial
Seawalls
|
*
|
|
|
|
Marine
Mammal Habitat (North Lantau)
|
|
*
(Indo - Pacific Humpbacked dolphin)
|
|
|
Marine
Mammal Habitat (Northeast Lantau)
|
|
*
(Indo - Pacific Humpbacked dolphin)
|
|
|
Marine
Mammal Habitat (East Lantau)
|
*
(Finless Porpoise)
|
*
(Indo - Pacific Humpbacked dolphin)
|
|
8.3.13
A map
detailing the locations of these habitats is presented on Figure 8.3a.
8.4.1
A desktop
literature review and supporting field surveys (summarised above in Section 8.3 and detailed in full in Annex F) were conducted, in both the wet
and dry seasons where applicable, in order to establish the ecological profile
of the area within and surrounding the Study Area. Information from the water quality assessment was used to refine
the size of the area under study as that potentially affected by perturbations
to water quality parameters (Figure 8.2a). This area became the focus for this
ecological impact assessment. The
importance of potentially impacted ecological resources identified within the
Study Areas were assessed using the EIAO
TM. The potential impacts due to
the construction and operation of the NLDFS and associated developments were
then assessed (following the EIAO TM Annex 16 guidelines) and the impacts
evaluated (based on the criteria in EIAO
TM Annex 8).
Construction Phase Direct Impacts
8.5.1
Impacts to
marine ecological resources arising from the construction works may be divided
into those due to direct disturbances to that habitat and those due to
perturbations to key water quality parameters.
8.5.2
Direct
impacts to marine ecological resources include habitat loss due to the dredging
and reclamation associated with the proposed NLDFS. The construction of the following reclamations form the NLDFS
(detailed descriptions of each reclamation area are provided in the Project
Description - Section 2):
·
39 ha of seabed associated with the reclamation
for the Siu Ho Wan residential development, promenade and special duties unit;
·
65 ha of seabed associated with the reclamation
for the Northshore developments(including Theme Park Gateway, Ferry Terminal,
Road P1, Tourist & Convention Village and the Specialist Sport Complex);
·
49 ha of seabed associated with the Fa Peng and
Chok Kwo Wan Link Road Phase 1 reclamations;
·
25 ha of seabed associated with the Chok Kwo Wan
Link Road Phase 2; and,
·
80 ha of seabed associated with the Theme Park
(Phase III) Extension.
Cumulative Direct Losses of
Habitats
8.5.3
It is
important to include in this EIA the direct losses of habitats along the North
Lantau shoreline that will be affected by other projects planned for the
area. Two specific projects have been
included in this assessment, the construction of the Theme Park and the Route
10 highway.
8.5.4
Theme Park EIA:
The construction of the Theme Park and its associated developments will
involve the direct loss of the following habitats:
·
The loss of 3.08 km natural intertidal habitats
which are of low to medium ecological value and the loss of 1.27 km of sloping
seawalls. The residual impact is
considered to be acceptable as the loss of these organisms will be compensated
by the provision of 3.9 km of sloping seawalls that have been demonstrated to
become recolonised by assemblages of similar nature after construction;
·
The loss of 0.298 ha subtidal hard surface
habitats which are of high ecological value.
The residual impact is considered to be acceptable as the loss of these
organisms is compensated by the provision of 3.9 km of rubble mound/rock or
concrete armour seawall, of which 4.3 ha would be suitable for corals to
colonise and grow; and,
·
The loss of 280 ha of the subtidal soft bottom
assemblages within the Penny’s Bay Park reclamation site and 10 ha within the
Yam O site. The residual impact is
considered to be acceptable as the habitat is of low ecological value.
8.5.5
Route 10 EIA:
The construction of Route 10 and its associated developments will
involve the direct loss of the following habitats:
·
Dredging and reclaiming an area of soft bottom
subtidal habitat of low ecological value (6 ha) between the outer edges of the
headlands at Tso Wan and Fa Peng for the construction of the Toll Plaza and
associated seawalls.
8.5.6
As a result
of the small area lost and its low ecological value no mitigation measures were
proposed although it should be noted that the seawalls for the Toll Plaza will
be sloping rubble mound/rock or concrete armour design and thus ecologically
enhancing.
Subtidal Soft Benthos
8.5.7
Impacts to
benthic organisms are dependent upon the location of the assemblages in
relation to the reclamation site.
Within the reclamation site, primary impacts will be the smothering and
burial of organisms during filling, or removal during dredging, which are
present there. These impacts will
necessarily occur during dredging and sandfilling operations associated with
the reclamation works. It is important,
therefore, to determine whether the reclamation site contains unique or
otherwise noteworthy benthic assemblages which will be lost. Findings from a review of the literature,
supported by focussed field surveys, indicate that the benthic assemblage
within, and in the vicinity of, the reclamations were dominated by polychaetes
and characterised by similar species diversity and biomass as elsewhere in Hong
Kong. All the species recorded occur
frequently in Hong Kong and no rare species were observed. As a result, the assemblages when compared
with other areas in Hong Kong were regarded as being of low ecological value.
8.5.8
Although
epifaunal benthic surveys have identified sparsely distributed colonies of
gorgonians and soft corals of ecological interest at Tsing Yi to the east of
the areas to be reclaimed, no rare or environmentally sensitive species were
recorded in proximity to the reclamation areas. Although the proposed reclamation will result in the loss of a
total of 258 hectares of subtidal soft benthic habitats, the severity of the
impact is anticipated to be acceptable as the areas to be reclaimed are of low
ecological value.
8.5.9
The total
cumulative loss of soft bottom benthic habitat as a result of the Theme Park,
Route 10 and NLDFS projects is 558 ha the severity of which is anticipated to
be acceptable as the areas to be reclaimed are of low ecological value.
Subtidal Hard Surface Habitats
8.5.10
The
construction of the reclamation's for the Projects will result in the permanent
loss of high ecological value subtidal hard surface habitats as follows:
•
High Ecological Value - 0.10 ha (1,000 m in
length and 1 m in depth) along the Pa Tau Kwu coastline; and,
•
High Ecological Value - 0.06 ha (600 m in length
and 1 m in depth) along the Fa Peng coastline.
8.5.11
The
assemblages at Fa Peng and Chok Kwo Wan Link Road Phase 2 reclamation areas
will be lost through the burial of organisms present there. These impacts will necessarily occur during
dredging and filling operations associated within the reclamation works.
8.5.12
Rubble
mound and/or armour rock/concrete armour seawalls will be used along the Chok
Kwo Wan Link Road Phase 2 and Fa Peng reclamations and will provide 3.1
ha
of habitat for subtidal organisms to colonise. It has been demonstrated that marine organisms have recolonised
such seawalls after construction .
It is anticipated that assemblages of hard corals will settle on and
recolonise the newly constructed seawalls, as environmental conditions of that
area would be similar to existing conditions that have allowed the growth of
hard corals recorded from field surveys of Penny’s Bay. The potential habitat provided by the total
surface area of the rubble mound and/or armour rock/concrete armour seawalls on
the Chok Kwo Wan Link Road Phase 2 and Fa Peng reclamations (greater than 3.1
ha) is expected to mitigate for the loss of high ecological value assemblages
of hard corals within the reclamation sites (approximately 0.16 ha).
8.5.13
The total
cumulative loss of subtidal hard surface habitats of high ecological value as a
result of the Theme Park and NLDFS projects is 0.458 ha. The loss of this habitat unmitigated is
unlikely to be acceptable hence the provision of rubble mound/rock or concrete
armour sloping seawalls on the Chok Kwo Wan Link Road Phase 2 and Fa Peng
reclamations for the NLDFS and sloping seawalls along the Penny’s Bay
reclamation is expected to provide greater than 7.4 ha of habitat suitable for
colonisation by corals. With these
mitigation measures in place the cumulative loss of subtidal habitat is
considered to be acceptable.
Intertidal Habitats - Rocky
Shores, Sandy Shores and Artificial Seawalls
8.5.14
A total
length of 1.6 km of the natural intertidal habitats composed mainly of rocky
shores and some small sandy shores on the Tsing Chau Tsai headland, will be
lost as a result of reclamation activities for the NLDFS. A 3.0 km stretch of sloping artificial
shoreline (Siu Ho Wan and Yam O to To Kau Wan) on the northern coast of Lantau
will be lost as a result of reclamation activities. The results from field surveys indicated that the intertidal
assemblages recorded on the rocky shores are typical of exposed rocky shore
communities observed in Hong Kong.
These intertidal habitats will be replaced by artificial seawalls. The artificial seawalls can, over time,
support similar assemblages of intertidal fauna and flora. Organisms present on intertidal shores in
Hong Kong rely on larval settlement for recruitment. Assuming that there is a regular supply of larvae brought to the
area, recolonisation of new seawalls resulting from the reclamation will
occur. The design of the seawall will
be critical in determining the extent to which the community re-establishes
post reclamation. The more
heterogeneous the seawall, the more diverse a community the habitat can support
such as tetrapods or rubble mound/rock or concrete armour. The seawall should, therefore, be designed
to maximise substrate heterogeneity in an attempt to create a productive
post-reclamation area. Although the
reclamation works will result in the loss of 4.6 km of intertidal habitats, the
severity of the impact is reduced by the provision of greater 11.3 km of
sloping ecologically enhancing seawalls.
The sloping seawalls are all expected to be of rubble mound/rock or
concrete armour design and will be located in the following areas (Figure 8.5a):
·
Siu Ho wan to Yam Tsai Wan = 4 km;
·
Yam O Tuk to To Kau Wan = 3.4 km;
·
Route 10 Toll Plaza to Route 10 HK Link (Fa Peng
and Chok Kwo Wan Road Phase 2 reclamations) = 2.5 km; and,
·
Theme Park (Phase III) Extension = 1.4 km.
8.5.15
The total
cumulative loss of intertidal habitats as a result of the Theme Park and NLDFS
projects is 4.68 km of natural shoreline and 4.27 km of sloping artificial
seawalls. The severity of which is
anticipated to be acceptable in the light of the provisioning of greater than
15.2 km of sloping artificial seawalls that are ecologically enhancing.
Intertidal Habitats - Mangrove
and Mudflat
8.5.16
The small
mangrove and mud flat located within the southern corner of Yam O Wan will be
directly lost as a result of the construction of the NLDFS specifically by the
Road P1. The mangrove of low ecological
value has been disturbed by the log pond in Yam O Bay, is small (< 0.5 ha)
and is not regarded as an important mangrove in Hong Kong. Consequently, mitigation for the loss of
this mangrove and mudflat is not considered necessary.
Marine Mammals
8.5.17
Reclamations
and other marine construction activities can result in a loss of habitat for
dolphins. The physical loss of habitat
during and after reclamation works for the Projects could affect the small
population of humpback dolphins that utilise the North, East and Northeast
Lantau areas on a seasonal basis. Few
sightings have, however, been made within the areas scheduled to be
reclaimed. As the areas are not critical
habitat for the dolphin (such as Northwest waters of Lantau), but seasonal,
this impact is unlikely to affect the dolphin population as a whole and is
deemed acceptable. Because Finless
Porpoises occur only to the south of the Study Area habitat loss should not be
a factor for this species.
8.5.18 Although
many development projects may have an insignificant impact on the status of the
dolphin population in Hong Kong when viewed in isolation, impacts of several
projects may be important when assessed together. In view of this fact, it is important to evaluate the cumulative
effects of various reclamation projects around Lantau Island on the
dolphins. The major reclamation around
Lantau Island in recent years was that associated with the development of Hong
Kong's International Airport at Chek Lap Kok.
At that time, no studies were undertaken to gather baseline data in
order to assess what impacts the loss of this potential habitat may have had on
the dolphins. However, based on recent
studies of the dolphins home range patterns (Hung 2000), it is speculated that
these works may have had an adverse impact.
Certainly, the combined loss of habitat in the North Lantau and
northwestern New Territories has reduced the amount of natural coastal habitat
for dolphins, however, due to the fact that humpback dolphins do not appear to
be highly concentrated near shorelines in Hong Kong's inshore waters, such loss
of habitat is probably not of major importance to the population.
8.5.19 The
primary concern with the loss of habitat, and the accumulation of impacts from
concurrent projects is the overall loss of natural coastline and its
concomitant effects on the prey species of the dolphins. Information from the fisheries impact
assessment (Section 9) indicates that
direct impacts due to the reclamations are not predicted to seriously impact
fisheries due to the generally low levels of production in the Study Area. None of the areas to be lost are recognized
spawning and nursery areas and hence juvenile fish stocks are unlikely to be
affected. The consequences of this are
that impacts to marine mammals through loss of food supply (fisheries resources)
are not predicted to occur as impacts to fisheries resources are regarded as of
low severity and acceptable.
Construction
Phase Indirect Impacts
8.5.20
Sensitive
receivers for marine ecological impact assessment have been identified to
assess the potential indirect impacts to resources outside the reclamation
areas as a result of perturbations to water quality, during both the
construction and operation phases.
Information presented in the review of literature and in the results of
the comprehensive field surveys has indicated that the Study Area (excluding
the habitats within the reclamation footprints) contains the following marine
ecology sensitive receivers:
·
Habitat for the Indo-pacific Humpbacked Dolphin
in the coastal waters of North, Northeast and East Lantau.
·
Assumed high ecological value hard coral
assemblages located at Sze Pak Wan.
·
Medium ecological values hard coral assemblages
located on Kau Yi Chau.
8.5.21
It is
considered important to the environmental acceptability of the Projects that
construction and operational activities of the proposed NLDFS do not impact
these sensitive receivers. The
following sections discuss and evaluate the impacts to marine ecological
habitats specifically focusing on those listed in Table 8.3a.
8.5.22
Indirect
impacts to marine ecological resources during the construction phase include
sediment release associated with the above construction projects. Potential impacts to water quality from
sediment release are listed below:
·
increased concentrations of suspended solids
(SS);
·
a resulting decrease in DO concentrations; and,
·
an increase in nutrient concentrations in the
water column.
8.5.23
The
construction of the reclamations for the Northshore Lantau Development will
involve dredging of the existing marine sediments along the line of the
seawalls to provide suitable foundations and filling of the reclamations using
sand and public fill. The reclamations
will be constructed using the drained method of construction, which means that
the existing sea bed sediments under the reclamations will be left in place,
except under the seawalls. This
construction method is more environmentally protective as its minimises
dredging and hence perturbations to water quality and also reduces the amount
of sediment required to be disposed at gazetted mud disposal sites.
Suspended Solids (SS)
8.5.24
Subtidal Hard Surface Habitats:
Soft corals, gorgonians, hard corals and anemones may be injured by both
high suspended sediment concentrations and high deposition rates. Damage (sublethal effects) or mortality
(lethal effects) can result from a reduction in light penetration which kills
the photosynthesizing symbiotic algae associated with the hard corals, and also
from the deposition of sediment onto the corals surface which physically blocks
the respiratory and feeding apparatus.
An assessment of the effects of backfilling in Mirs Bay(8)
assumed that prolonged turbidity and a sustained sedimentation rate of 20 mg cm-2
day-1 (= 0.2 kg m-2 day-1) was damaging to
corals.
8.5.25
Impacts to
corals on the rocky coasts of Sze Pak Wan and Kau Yi Chau are unlikely to occur
as sediment deposition rates from the reclamation works are predicted to be
less than 0.01 kg m-2 day-1 at Sze Pak Wan and less than
0.025 kg m-2 day-1 at Kau Yi Chau (see water quality
assessment in Section 5 - Scenario 3)
which is below the threshold value discussed above for corals. Consequently impacts are predicted to be
within environmentally acceptable levels.
Negative impacts to corals may also arise from increased SS in the water
column. A threshold value is, however,
unavailable for corals specific to Hong Kong waters. The habitats identified as supporting hard coral assemblages at
Kau Yi Chau and Sze Pak Wan were represented in the water quality modelling. Elevations of SS at these locations were
predicted to be 1.2 mg L-1 at Sze Pak Wan and 1.4 mg L-1
at Kau Yi Chau under the worst case scenario (Scenario 3 see Section 5). An elevation of this magnitude is very small and the total SS
level is compliant with the WQO for this area.
It is thus expected that unacceptable impacts to corals at Kau Yi Chau
and Sze Pak Wan arising from elevated SS levels will not occur.
8.5.26
Subtidal Soft Benthos:
Sessile organisms within the benthos will be susceptible to the effects
of increased sediment loads. Effects
can be lethal or sublethal (eg reduction in reproductive potential due to
stress incurred by constantly having to flush out the depositing
material). The effects of sedimentation
on organisms will also depend on other factors, such as an organism's tolerance,
growth orientation of sessile organisms and water movement. Infaunal benthic assemblages in Hong Kong
are located in soft muds and sands which are frequently disturbed by storms,
seabed currents and constant trawling activity which reworks the sediments
creating high suspended sediments loads in the water column. Benthic invertebrates are therefore not
likely to be adversely affected by the dredging and filling operations with
respect to sediment suspension and settlement but more so from direct habitat
loss within the reclamation areas (see above for discussion).
8.5.27
Impacts to
benthic assemblages immediately outside of the reclamation site are expected to
occur temporarily as deposition rates are predicted to be 0.05 kg m-2
day-1. The area is expected
to be small as sediment will be deposited within a short distance of the
dredging and filling works. At Sze Pak
Wan, levels are much lower and predicted to be less than 0.01 kg m-2
day-1. These predicted
deposition rates are not likely to impact the natural benthic assemblages as
the area is often disturbed by demersal trawling and seabed erosion due to the
main flow channel from Ma Wan; the organisms present are thus assumed to be
adapted to seabed disturbances. Based
on the assumption that eventually the affected areas will be recolonised by
fauna typical of the area, then the temporary loss of these low ecological
value assemblages are deemed acceptable.
8.5.28
Intertidal Habitats:
Intertidal habitats within the Study Area which may be affected by the
reclamation activities include the ungazetted sandy beaches located at Sze Pak
Wan, Sam Pak Wan, Yi Pak Wan and Discovery Bay and the gazetted beaches on Ma
Wan Island. Sediment dispersion results
predict that SS concentrations will not exceed the WQO's at any of these
shores. However, the water quality
assessment predictions will be verified in the field during construction using
the environmental monitoring and audit programme (EM&A). Based on these conditions, impacts to the
ecological assemblages present at these beaches are not predicted to be
unacceptable. Higher than normal
sediment loads arising from nearby dredging works were deposited on an
assemblage of coralline algae at Cape d'Aguilar to the south of Hong Kong. This resulted in overgrowth of the coralline
assemblage by the red turf alga, Gelidium
pusillum, which became the most abundant species(). Scouring, due to very high SS levels (eg
> 100 mg L-1) may inhibit the survival of algae, thereby reducing
the food supply to the numerous rocky shore herbivores and causing intolerant
or less competitive species to become locally extinct. The water quality assessment scenarios
indicate that no exceedances of the WQO will occur at the rocky coastal areas
at Sze Pak Wan. The predictions will be
verified in the field during construction using the EM&A. It is thus expected that unacceptable
impacts to these intertidal assemblages arising from elevated SS levels will
not occur.
8.5.29
Marine Mammals:
Mobile animals such as marine mammals have the ability to avoid areas
where SS levels have increased, thus avoiding any impacts. Impacts can occur to these mammals as an
indirect result of increased SS levels.
The construction of the NLDFS and associated facilities may cause
perturbations to water quality which have the potential to impact the fisheries
resources of the Northeast and East Lantau area. The Indo-Pacific Humpbacked Dolphin, Sousa chinensis, in Hong Kong waters feed primarily on fish. The dolphins are often seen associated with
pair trawlers which are likely to provide them with increased feeding
opportunities; this appears to be confirmed by the limited data available from
stomach contents analyses. By examining
the stomachs of 12 stranded dolphins, Jefferson (1998) found that, with the
exception of one individual’s stomach content which contained some squid
remains, only fish had been consumed.
At least twenty species of fish belonging to 13 families were found in
the stomach of these stranded dolphins. The most abundant families were
anchovies - Engraulidae, croakers - Sciaenidae, and sardines - Clupeidae
accounting for more than 81% of all fish in the stomachs of the stranded
dolphins.
8.5.30 The Finless Porpoise, Neophocaena phocaenoides, is thought to
be an opportunistic feeder with known prey including crustaceans (shrimps and
prawns), cephalopods (squid and octopus) and small pelagic fish of low
commercial value (anchovies, croakers and sardines). They are thus likely to be affected by any significant changes in
key water quality parameters (such as SS and DO) arising from the
development. A deterioration in water
quality is likely to cause these mobile fish to move out of the area thus
interfering with the dolphin and porpoises normal feeding patterns. Information from the
fisheries impact assessment (Section 9)
indicates that indirect impacts due to the reclamations are not predicted to
seriously impact fisheries due to the generally low levels of production in the
Study Area. None of the areas to be
lost are recognized spawning and nursery areas and hence juvenile fish stocks
are unlikely to be affected. The
consequences of this are that impacts to marine mammals through loss of food
supply (fisheries resources) are not predicted to occur as impacts to fisheries
resources are regarded as of low severity and acceptable.
8.5.31
As
mentioned above for corals, the predicted elevations of SS in areas where the
mammals are frequently sighted (such as South Lamma for the Finless Porpoise or
the Brothers for the Indo-Pacific Humpbacked Dolphin) are small and within
environmentally acceptable levels (as defined by the WQO's). It is thus expected that unacceptable
impacts to these marine mammals arising from elevated SS levels will not occur.
8.5.32
Introduction
of environmental contaminants desorbed from suspended sediment particles
(especially inorganic contaminants such as mercury and pesticides such at DDT)
can have damaging effects on dolphins and porpoises. As discussed in the water
quality assessment contaminant release (specifically copper, arsenic and silver
which are the only metals which exceed the LCEL sediment criteria standard)
from dredging of contaminated sediments is not predicted to exceed
environmental standards. Consequently,
unacceptable impacts to marine mammals from contaminated release during
dredging are not predicted to occur.
Dissolved Oxygen
8.5.33
The
relationships between SS and DO are complex, with increased SS in the water
column combining with a number of other effects to reduce DO concentrations in
the water column. Elevated SS (and
turbidity) reduces light penetration, lowers the rate of photosynthesis by
phytoplankton (primary productivity) and thus lowers the rate of oxygen
production in the water column. This has a particularly adverse effect on the
eggs and larvae of fish, as at these stages of development, high levels of
oxygen in the water are required for growth due to their high metabolic
rate. Although respiratory responses
and tolerance of hypoxia were studied in two marine fish([10]),
it is not possible to set critical thresholds for this parameter for other
marine organisms due to lack of tolerance data for species in Hong Kong. DO depletions are most likely to affect
sessile organisms as they cannot move away from areas where DO is low (unlike
mobile species such as fish).
Depletions of DO as a result of construction activities for the
reclamations are very small and compliant with the relevant WQOs and do not
impact and marine ecological sensitive receivers.
Nutrients
8.5.34
High levels
of nutrients in seawater can cause rapid increases in phytoplankton often to
the point where an algal bloom occurs.
An intense bloom of algae can lead to sharp decreases in the levels of
dissolved oxygen in the water as dead algae fall through the water column and
decompose on the bottom. Anoxic
conditions may result if DO concentrations are already low or are not
replenished. This may result in
mortality to marine organisms due to oxygen deprivation. Elevations in unionised ammonia as a result
of construction activities are not predicted to exceed the WQO at any of the
sensitive receivers. It is noted that
the background concentration for total inorganic nitrogen (TIN) exceeds the
WQO. However, as discussed in the water
quality assessment (Section 5) the
contribution of the NLDFS construction works to the non-compliance is
negligible and not considered to be an adverse impact to water quality. It is thus expected that unacceptable
impacts to the marine ecological habitats and species present in the Study Area
arising from these very small elevations in TIN will not occur.
High and Low Frequency Noise
8.5.35
As
cetaceans are protected under the Wild
Animals Protection Ordinance (Cap 170), 1980 any lethal and sublethal
impacts due to underwater noise on marine mammals will be deemed
unacceptable. Cetaceans are animals
that rely heavily on acoustic information to communicate and to explore their
environment. Therefore, any noise that
disrupts communication or echolocation channels would be potentially
harmful. High explosives produce pulses
with a very rapid onset (shock waves), which change to conventional acoustic
pulses as they propagate. The reactions
from impacted cetaceans can range from brief interruption of normal activities
to short- or long-term displacement from noisy areas. Strong sound may cause temporary or permanent reductions in
hearing sensitivity. Information from
the engineering consultants indicates that no explosives will be used in the
construction process in the sea or nearshore environment.
8.5.36
Studies
have shown that because of the efficient transfer of sound in water, dolphins
can detect noises associated with vessels similar to dredgers at distances up
to approximately 5 km .
Noise disturbance interferes with communication and echolocation pulses
which are used for navigation and feeding, leading to behavioural changes. There is evidence suggesting that some
cetacean species will minimise their use of areas affected by underwater noise.
8.5.37
Most
dolphins can hear within the range of 1 - 150 kHz though the peak for a variety
of species is between 8 - 90 kHz(). Dredging and large vessel traffic generally
results in mostly low frequency noise typically in the range of 0.02 - 1 kHz()
which are below the peak range of 8 - 90 kHz reported for dolphins and
therefore, would not likely cause problems.
Percussive piling work may be involved in the construction process for
the cross boundary ferry piers and the Road P1 between Siu Ho wan and Ta Pang
Po. Mitigation measures will be
required during construction to prevent unacceptable impacts to marine mammals
in the vicinity of the works if the construction takes place during the autumn
and winter when dolphins are thought to use the area.
Vessel Traffic
8.5.38
Increases
in marine traffic may disturb normal cetacean movement patterns through
potential collision with vessels, increased turbidity generated by propellers
and submerged equipment. Both dolphins
and porpoises in Hong Kong have been found to have been killed by vessel
collisions (Parsons and Jefferson in press).
Additionally, vessel passes and noise can cause behavioural disturbance
to these animals. This could affect
both species. Increased vessel traffic
through the Kap Shui Mun channel would likely affect mostly humpback dolphins
and any increase in traffic from the south of Penny's Bay would most likely
have an impact on finless porpoises.
Vessel traffic from Victoria Harbour to the east should not adversely
impact either species as the harbour areas and the east of Penny’s Bay are not
important dolphin or porpoise habitats.
A moderate increase in the number of large, slow-moving (less than 10
knots) vessels in the area should not cause a significant impact to dolphins or
porpoises. Smaller, faster
outboard-driven boats would be more of a concern, because of the fast approach
speeds and higher potential for high frequency noise. However, it is not anticipated that vessels associated with construction of the NLDFS will be of the latter
type.
8.5.39
Operational
impacts to marine ecological resources may occur through the following:
Hydrodynamic Regime
8.5.40
Impacts to
marine ecological resources could potentially occur if the shape of the
reclamation causes a change on the hydrodynamic regime of the East Lantau
coastline. Impacts of this nature could
lead to increased seabed current speeds which may cause seabed scour thus
impacting subtidal assemblages, or conversely the current speeds may drop
affecting flushing and water exchange of an area. Inadequate flushing could lead to reduction in dissolved oxygen
(DO) an increase in nutrients and consequent impacts to marine ecological
resources. The hydrodynamic modelling (Section 5) has indicated that the
reclamation on the northern shore of Lantau will have little effect on current
speed although the flushing rate of Yam O Wan will be reduced. The effect of the NLDFS and Container
Terminal is a reduction in current speeds in Sze Pak Wan and Discovery Bay
which will cause a slight increase in salinity.
8.5.41
These
impacts will be required to be studied in detail for each of the Schedule 2
EIAs that comprise the NLDFS including surveys and investigations into the
effects of current changes on affected ecological habitats. It is unlikely that these impacts will be
insurmountable given that on-site mitigation measures involving revisiting the
shape and size of the reclamations can be incorporated. If these mitigation measures cannot be
incorporated then off-site mitigation measures such as the deployment of
artificial reefs should be examined in accordance with the PELB TC No 1/97
(Guidelines for Implementing the Policy on Off-site Ecological Mitigation
Measures) or any subsequent technical circular issued to replace PELB TC No
1/97.
Stormwater Run-off and Drainage
8.5.42
During the
operation of the NLDFS pollutants derived from sewage effluent and stormwater
will be discharged to the marine waters.
Sewage effluents from the NLDFS and associated developments (eg hotels)
will be collected and transported for treatment to the Siu Ho Wan Sewage
Treatment Works (STW) via sub-surface sewerage pipelines. The effluents will be treated at the Siu Ho
Wan STW and discharged to the marine waters to the north of the STW via a
submarine outfall. During the operation
of the NLDFS and associated developments, the Siu Ho Wan STW will also treat
effluents from the Hong Kong International Airport, the Tung Chung and Tai Ho
developments Discovery Bay and S Lantau.
The increase in the treated effluent flows and loads from the NLDFS and
associated developments will have the potential to cause adverse impacts to
water quality and subsequent impacts to marine ecological resources. The stormwater may contain contaminants,
which would have the potential to cause adverse impacts to water quality and
marine ecology, most likely in the immediate vicinity of the discharge points
due to the relatively low flow rates from these culverts.
8.5.43
All
discharges during the operational phase of the Projects are required to comply
with the Technical Memorandum for
Effluents Discharged into Drainage and Sewerage Systems, Inland and Coastal
Waters (TM) issued under Section 21
of the WPCO. The TM defines discharge limits to different
types of receiving waters. Under the
TM, effluents discharged into the drainage and sewerage systems, inshore and
coastal waters of the WCZs are subject to pollutant concentration standards for
particular discharge volumes. Any new
discharges within a WCZ are subject to licence conditions and the TM acts as a
guideline for setting discharge standards for the licence. It is anticipated that all stormwater
discharges through surface run-off or drainage systems will be compliant with
the TM. Compliance with the TM will
ensure that no adverse impacts will occur to marine ecological resources in the
vicinity of the project. Compliance is
expected to be achieved according to the measures outlined in Section 5 of this EIA.
Vessel Traffic
8.5.44
As
discussed in Section 8.5.38 high
speed vessel traffic may disturb normal cetacean movement patterns through
potential collision with vessels, increased turbidity generated by propellers and
submerged equipment. Information available concerning the operation of cross
boundary ferries from the proposed terminal east of Yam O, indicates that up to
80 high speed ferries per day may travel from the North Lantau coastline to the
Pearl River Delta region. This is
likely to cause unacceptable impacts to the dolphins and mitigation measures
will be required when the vessels pass through critical habitat located in the
vicinity of the Sha Chau Lung Kwu Chau Marine Park.
8.6.1
The
following section discusses and evaluates the impacts to marine ecological
habitats. From the information
presented above the marine ecological impacts associated with the construction
and operation of the NLDFS Projects are as follows:
·
Direct loss of 39 ha of low ecological value
soft bottom benthic habitat associated with the reclamation for the Siu Ho Wan
residential development, promenade and special duties unit;
·
Direct loss of 65 ha of low ecological value
soft bottom benthic habitat associated with the reclamation for the Northshore
developments(including Theme Park Gateway, Ferry Terminal, Road P1, Tourist
& Convention Village and the Specialist Sport Complex);
·
Direct loss of 49 ha of low ecological value
soft bottom benthic habitats associated with the Fa Peng and Chok Kwo Wan Link
Road Phase 2 reclamations;
·
Direct loss of 25 ha of low ecological value
soft bottom benthic habitat associated with the Chok Kwo Wan Link Road Phase 2;
·
Direct loss of 80 ha of low ecological value
soft bottom benthic habitat associated with the Theme Park Extension;
·
Direct loss of 0.10 ha of high ecological value
hard surface subtidal habitat along the Pa Tau Kwu coastline (Fa Peng and Chok
Kwo Wan Link Road Phase 2 reclamations);
·
Direct loss of 0.06 ha of high ecological value
hard surface subtidal habitat along the Fa Peng coastline (Fa Peng and Chok Kwo
Wan Link Road Phase 2 reclamations);
·
Direct loss of a total length of 1.6 km of
medium and low ecological value natural rocky shores and sandy shores as a
result of the Fa Peng and Chok Kwo Wan Link Road Phase 2 reclamations;
·
Direct loss of a 3.0 km stretch of low
ecological value sloping artificial seawalls between Siu Ho Wan to Yam O West,
and Yam O East to To Kau Wan as a result of Siu Ho Wan and Northshore
reclamations;
·
Direct loss of a 0.5 ha low ecological value
mangrove and 2.5 ha low ecological value mudflat within Yam O Wan as a result
of the Northshore reclamation for Road P1;
·
Indirect and temporary disturbance to the
seasonal population of marine mammals (autumn and winter) due to underwater percussive piling work for the cross boundary ferry piers
and the Road P1 between Siu Ho wan and Ta Pang Po; and,
·
Indirect but long term potential disturbance to
critical dolphin habitat in northwest waters of Hong Kong arising from the
passage of high speed ferries from the cross boundary ferry terminal to the
Pearl River Delta region.
8.6.2
An
evaluation of the above ecological impacts has been conducted for each of the
reclamations that comprise the NLDFS in accordance with the EIAO TM Annex 8 Table 1. The evaluations
are presented in Table 8.6a.
8.6.3
The
construction of the Theme Park and its associated developments will involve the
direct loss of the following habitats: 3.08 km natural intertidal habitats
which are of low to medium ecological value and the loss of 1.27 km of sloping
seawalls; the loss of 0.298 ha subtidal hard surface habitats which are of high
ecological value; the loss of 280 ha of the subtidal soft bottom assemblages
within the Penny’s Bay Park reclamation site and 10 ha within the Yam O
site. The construction of Route 10 and
its associated developments will involve the direct loss of soft bottom
subtidal habitat of low ecological value (6 ha).
8.6.4
The
cumulative losses as a result of the NLDFS, Theme Park and Route 10 are as
follows:
·
The direct loss of 558 ha of soft bottom benthic
habitat, the severity of which is anticipated to be acceptable as the areas to
be reclaimed are of low ecological value.
·
The direct loss of 0.458 ha of subtidal hard
surface habitats of high ecological value is unlikely to be acceptable without
mitigation. The provision of rubble
mound/rock or concrete armour sloping seawalls is expected to provide greater
than 7.4 ha of habitat suitable for colonisation by corals. With these mitigation measures in place the
residual cumulative loss of subtidal habitat is considered to be acceptable.
·
The direct loss of 4.68 km of natural and 4.27
km of artificial intertidal habitats, the severity of which is anticipated to be
acceptable in the light of the provisioning of greater than 15.2 km of sloping
artificial seawalls that are ecologically enhancing.
8.6.5
The overall
severity of the cumulative losses of habitats is regarded as high without
mitigation. However, mitigation
measures described below reduce the severity of the residual impacts to of low
severity and acceptable.
Marine Ecological Resources: General
8.7.1
The above
assessment indicates that during reclamation, the direct and indirect impacts
on intertidal communities and subtidal hard bottom and soft bottom assemblages
are anticipated to be environmentally acceptable. Constraints on controlling impacts to water quality to within
acceptable levels during reclamation are expected to also control impacts on
marine ecology. In accordance with the
guidelines in the EIAO TM on marine
ecology impact assessment the general policy for mitigating impacts to marine
ecological resources, in order of priority, are:
·
Avoidance: Potential impacts should be avoided to the
maximum extent practicable by adopting suitable alternatives;
·
Minimisation: Unavoidable impacts should be minimised by
taking appropriate and practicable measures such as constraints on intensity of
works operations (eg dredging rates) or timing of works operations; and
·
Compensation: The loss of important species and habitats
may be provided for elsewhere as compensation.
Enhancement and other conservation measures should always be considered
whenever possible.
8.7.2
The previous
discussion (Section 8.5) has
indicated that the loss of intertidal and subtidal assemblages within the Study
Area is expected to be mitigated through provision of seawalls that provide
adequate surfaces for colonisation once reclamation works have been completed
(11.3 km of rubble mound and/or concrete armour seawalls and subtidally 3.1 ha
at Pa Tau Kwu and Fa Peng). In order to
assist in rehabilitating the area after reclamation, a rubble mound or concrete
armour rock design should be adopted for the construction of the seawalls. It has been demonstrated that marine
organisms have recolonised these seawalls after construction(4). It is anticipated that intertidal and
subtidal assemblages similar to those recorded in the field surveys, will
settle on and recolonise the newly constructed seawalls of the reclamation.
8.7.3
Impacts to
marine ecological resources during operation of the NLDFS and associated
developments are predicted to be within environmentally acceptable levels in
ecologically important areas through controls on sewage discharges and site
run-off (as discussed in Section 5 -
Water Quality). Hence no marine
ecology specific mitigation measures to control discharges are required during
projects operation.
8.7.4
The Theme
Park project proponent will provide 3.9 km of ecologically enhancing seawall as
mitigation for the project impacts.
These seawalls are anticipated to provide greater than 4.3 ha for
colonisation by corals.
Marine
Ecological Resources: Marine Mammals
8.7.5
Measures to
mitigate the impact of the construction and operation of the Projects have been
developed in consultation with Dr Tom Jefferson of the Ocean Park Conservation
Foundation. The
following recommendations should be followed to minimize potential construction
and operation impacts on dolphins and porpoises:
1)
All
vessel operators working on the Projects construction or operation should be
given a briefing, alerting them to the possible presence of dolphins and
porpoises in the area, and the rules for safe vessel operation around cetaceans. If high speed vessels are used, they should
be required to slow to 10 knots when passing through a high density dolphin
area (the Chek Lap Kok platform north to Castle Peak and west to the boundary
of Hong Kong waters);
2)
The vessel operators should be required to use
predefined and regular routes, as these will become known to dolphins and
porpoises using these waters;
3)
The vessel operators should be required to
control and manage all effluent from vessels;
4)
A
policy of no dumping of rubbish, food, oil, or chemicals should be strictly
enforced. This should also be covered
in the contractor briefing;
5)
Every
attempt should be made to minimize the effects of construction of the Projects
on the water quality of the area;
6)
Any
construction work that could potentially harm dolphins (underwater percussive
piling) should be planned to take place in spring or summer, when dolphin
abundance is apparently lowest. In
particular, the winter season should be avoided;
7)
If
underwater percussive piling must be done in autumn or winter, then the
following steps should be taken:
·
An
exclusion zone of 500 m radius should be scanned around the work area for at
least 30 minutes prior to the start of piling.
If cetaceans are observed in the exclusion zone, piling should be
delayed until they have left the area; and
·
A
bubble curtain should be used to surround the piling barge and work area, and
the bubble curtain should be in operation during any time in which piling
occurs.
8)
Construction-phase
dolphin/porpoise monitoring should be conducted by a qualified research team,
to evaluate whether there have been any effects on the animals.
9)
Operation-phase
dolphin/porpoise monitoring should be conducted by a qualified research team,
to evaluate whether there have been any effects on the animals for the first
two years of operation of the cross boundary ferry terminal.
8.7.6
Impacts to
marine ecological resources and associated mitigation measures discussed above
have been summarised below in Table 8.7a.
Table
8.7a - Summary of Impacts and Mitigation
Requirements
|
Impacts
|
Mitigation Needs
|
|
Direct loss of 39 ha
of low ecological value soft bottom benthic habitat associated with the
reclamation for the Siu Ho Wan residential development, promenade and special
duties unit a.
|
None required.
|
|
Direct loss of 65 ha
of low ecological value soft bottom benthic habitat associated with the
reclamation for the Northshore developments(including Theme Park Gateway,
Ferry Terminal, Road P1, Tourist & Convention Village and the Specialist
Sport Complex) a.
|
None required.
|
|
Direct loss of 49 ha
of low ecological value soft bottom benthic habitats associated with the Fa
Peng and Chok Kwo Wan Link Road Phase 2 reclamations a.
|
None required.
|
|
Direct loss of 25 ha
of low ecological value soft bottom benthic habitat associated with the Chok
Kwo Wan Link Road Phase 2 a.
|
None required.
|
|
Direct loss of 80 ha
of low ecological value soft bottom benthic habitat associated with the Theme
Park (Phase III) Extension a.
|
None required.
|
|
Direct loss of 0.10
ha of high ecological value hard surface subtidal habitat along the Pa Tau
Kwu coastline (Fa Peng and Chok Kwo Wan Link Road Phase 2 reclamations).
|
Mitigated through
the provision of greater than 3.1 ha of sloping rubble mound/rock or concrete
armour seawalls that are suitable for colonisation by corals.
|
|
Direct loss of 0.06
ha of high ecological value hard surface subtidal habitat along the Fa Peng
coastline (Fa Peng and Chok Kwo Wan Link Road Phase 2 reclamations).
|
Mitigated through
the provision of greater than 3.1 ha of sloping rubble mound/rock or concrete
armour seawalls that are suitable for colonisation by corals.
|
|
Direct loss of a
total length of 1.6 km of medium and low ecological value natural rocky
shores and sandy shores as a result of the Fa Peng and Chok Kwo Wan Link Road
Phase 2 reclamations.
|
Mitigated through
the provision of greater than 11.3 km of sloping rubble mound/rock or
concrete armour seawalls that are suitable for colonisation by corals.
|
|
Direct loss of a 3.0
km stretch oflow
ecological value sloping artificial seawalls between Siu Ho Wan to Yam O
West, and Yam O East to To Kau Wan as a result of Siu Ho Wan and Northshore
reclamations.
|
Mitigated through
the provision of greater than 11.3 km of sloping rubble mound/rock or
concrete armour seawalls that are suitable for colonisation by corals.
|
|
Direct loss of a 0.5
ha low ecological value mangrove and 2.5 ha low ecological value mudflat
within Yam O Wan as a result of the Northshore reclamation for Road P1.
|
None required.
|
|
Indirect and
temporary disturbance to the seasonal population of marine mammals (autumn
and winter) due to underwater percussive piling
work for the cross boundary ferry piers and the Road P1 between Siu Ho wan
and Ta Pang Po.
|
Avoid percussive
piling during Autumn and Winter as far as possible otherwise bubble curtain
should be used to minimise propagation of underwater noise.
|
|
Indirect but long
term potential disturbance to critical dolphin habitat in northwest waters of
Hong Kong arising from the passage of high speed ferries from the cross
boundary ferry terminal to the Pearl River Delta region.
|
High speed vessels should be required to
slow to 10 knots when passing through a high density dolphin area, such as
the area around the Sha Chau Lung Kwu Chau Marine Park. Regular routes for the high speed vessels should
be used so dolphins become familiar with these and avoid these areas.
|
|
The construction of
the Theme Park and its associated
developments will involve the direct loss of the following habitats:
·
Intertidal - 3.08 km natural intertidal
habitats which are of low to medium ecological value and the loss of 1.27 km
of sloping seawalls;
·
Subtidal hard surface habitats - 0.298 ha
which are of high ecological value;
·
Subtidal soft bottom assemblages the loss of
280 ha of the within the Penny’s Bay Park reclamation site and 10 ha within
the Yam O site. b
|
Mitigated through
the provision of greater than 3.9 km of sloping rubble mound/rock or concrete
armour seawalls that are suitable for colonisation by intertidal organisms.
Mitigated through
the provision of greater than 4.3 ha of sloping rubble mound/rock or concrete
armour seawalls that are suitable for colonisation by corals.
None required.
|
|
The construction of
Route 10 and its associated developments will involve the direct loss of soft
bottom subtidal habitat of low ecological value (6 ha).c
|
None required.
|
|
Note:
a)
The residual impact is considered to be
acceptable as the habitat is of low ecological value and the sloping rubble
mound/rock or concrete armour seawalls (Total = 11.3 km, net gain = 8.3 km)
and Artificial Reefs to be deployed will assist in enhancing the marine
ecology of the area surrounding the completed reclamations.
b)
The residual impact is considered to be
acceptable as the habitat is of low ecological value and the sloping rubble
mound/rock or concrete armour seawalls (3.9 km) and Artificial Reefs to be
deployed will assist in enhancing the marine ecology of the area surrounding
the completed reclamations.
c)
The sloping rubble mound/rock or concrete
armour seawalls at the Toll Plaza and Artificial Reefs to be deployed will
assist in enhancing the marine ecology of the area.
|
8.8.1
Taking into
consideration the ecological value of the habitats discussed in the previous
sections and the resultant mitigation requirements, residual impacts occurring
as a result of the proposed NLDFS have been determined and are as follows:
·
The loss of 4.6 km of intertidal habitats which
are of low to medium ecological value. The
residual impact is considered to be acceptable as the loss of these organisms
will be compensated by the provision of 11.3 km of sloping rubble mound/rock or
concrete armour seawalls that have been demonstrated to become recolonised by
assemblages of similar nature after construction;
·
The loss of 0.5 ha of mangrove and 2.5 ha of
mudflat of low ecological value. The residual impact is considered to be
acceptable as the habitat is of low ecological value.
·
The loss of 0.16 ha subtidal hard surface habitats
which are of high ecological value. The
residual impact is considered to be acceptable as the loss of these organisms
is compensated by the provision of seawalls (providing 3.1 ha of habitat) that
have been demonstrated to become recolonised by assemblages of similar nature
after construction; and,
·
The loss of 258 ha of the subtidal soft bottom
assemblages within the reclamation sites.
The residual impact is considered to be acceptable as the habitat is of
low ecological value and the rubble mound/rock or concrete armour seawalls and
Artificial Reefs to be deployed (see below) will assist in enhancing the marine
ecology of the area surrounding the completed reclamations.
8.8.2
The
previous discussion (Section 8.5) has
indicated that the loss of intertidal and subtidal assemblages within the
reclamation area is expected to be mitigated through provision of seawalls that
provide adequate surfaces for colonisation once reclamation works have
completed. In order to assist in
rehabilitating the area after reclamation, a rubble mound/rock or concrete
armour design should be adopted for the construction of the seawalls. It has been demonstrated that marine
organisms have recolonised these seawalls after construction(5). It is anticipated that intertidal and
subtidal assemblages similar to those recorded in the field surveys, will
settle on and recolonise the newly constructed seawalls of the reclamation. The residual impact is considered to be
acceptable as corals and intertidal organisms are expected to colonise the
seawalls after construction. The
potential habitat provided by the surface area of the 11.3 km of rubble
mound/rock or concrete armour and/or concrete armour seawalls (3.1 ha at Pa Tau
Kwu and Fa Peng) is expected to effectively mitigate for the loss of the small
area (0.16 ha) of hard corals lost within the reclamation sites.
8.8.3
The
cumulative residual losses as a result of the NLDFS, Theme Park and Route 10
are as follows:
·
The direct loss of 558 ha of soft bottom benthic
habitat, the severity of which is anticipated to be acceptable as the areas to
be reclaimed are of low ecological value.
The residual impact is considered to be acceptable as the habitat is of
low ecological value and the rubble mound/rock or concrete armour seawalls and
Artificial Reefs to be deployed (see below) will assist in enhancing the marine
ecology of the area surrounding the completed reclamations.
·
The direct loss of 0.458 ha of subtidal hard
surface habitats of high ecological value is unlikely to be acceptable without
mitigation. The provision of rubble
mound/rock or concrete armour sloping seawalls is expected to provide greater
than 7.4 ha of habitat suitable for colonisation by corals. With these mitigation measures in place the
residual cumulative loss of subtidal habitat is considered to be acceptable.
·
The direct loss of 4.68 km of natural and 4.27
km of artificial intertidal habitats, the severity of which is anticipated to
be acceptable in the light of the provisioning of greater than 15.2 km of
sloping artificial seawalls that are ecologically enhancing.
8.8.4
The overall
severity of the cumulative losses of habitats is regarded as high without
mitigation. However, the mitigation
measures described reduce the severity of the residual impacts to of low
severity and acceptable.
8.8.5
Although
not specifically implemented for the NLDFS, but for the Theme Park development,
an additional habitat enhancement measure undertaken by the project proponent
of the Theme Park EIA is to deploy Artificial Reefs (ARs) in Hong Kong waters
at a site (or sites) to be decided upon consultation with the Director of
Agriculture, Fisheries and Conservation (AFCD) and others. At present AFCD is conducting a programme to
enhance existing marine habitats and fisheries resources through the siting,
construction and deployment of ARs. ARs
act as fish aggregation devices and provide hard bottom, high profile habitat
in areas without natural cover.
Colonisation of ARs occurs through settlement of the spores and larvae
of algae, corals and other benthic organisms.
The AR subsequently will provide food, shelter and a nursery ground for
commercial fish and, over the long term enhance fishery stocks.
8.8.6
Information
from the AFCD’s Artificial Reef Deployment Study
has reported that Japanese researchers have claimed that for ARs to be
effective in enhancing marine resources they should have a minimum volume of
400 m3. The Study also
determined that the stocking density of ARs should be no less than 1,500 m3
km-2. The total area of
seabed lost through reclamation works for the Theme Park and associated
developments was estimated at 290 ha (280 ha at Penny’s Bay and 10 ha for Yam
O). In order to enhance an equivalent
area of this size 4,350 m3 of ARs should be deployed (1,500 m3
x 2.9 km-2). One potential
location for the deployment of the ARs includes the area north of the Luk Keng
headland. It should be noted that the
location and scale of AR deployment within a particular site is limited by a
variety of constraints detailed in full in the Final Report for the Artificial Reef Deployment Study (CE 8/97).
Construction EM&A Requirements
8.9.1
The
dredging operations include constraints which act as appropriate mitigation
measures to control environmental impacts to within acceptable levels (Section 5). Actual impacts of construction activities will be monitored
through impacts to water quality (Section
5). EM&A activities designed to
detect and mitigate any unacceptable impacts to water quality will serve to
proactively protect against unacceptable impacts to marine ecological
resources. The water quality monitoring
programme will provide management actions and supplemental mitigation measures
to be employed should impacts arise, thereby ensuring the environmental
acceptability of the project.
8.9.2
According
to the EIAO TM Section 8.3 (c) an
EM&A programme would be required in a situation where:
·
"the project involves mitigation measures
of which the effectiveness may require a long period to establish"
8.9.3
This Section 8.3 (c) of the EIAO TM is applicable in this situation
as the effectiveness of providing rubble mound/rock or concrete armour seawalls
for the recolonisation of corals will take time to evaluate. In response to this it is recommended that
an ecological monitoring and audit programme be conducted to monitor the
process of recolonisation of the area once the construction works have been
completed. The following text presents
the preliminary Objectives, Methodology and Rationale for the ecological
monitoring. Before monitoring can
begin, details of the monitoring programme should be agreed with AFCD and EPD.
8.9.4
The
objective of the ecological monitoring programme is to determine the rate and
effectiveness of colonisation of the rubble mound/rock or concrete armour
seawall by coral assemblages.
Ecological monitoring and audit will consist of subtidal dive surveys
after reclamation works have ceased.
Once the seawalls are constructed the frequency of monitoring should be
at six monthly intervals for a period of three years. This monitoring and audit will be used to assess the extent of
recolonisation of rubble mound/rock or concrete armour seawalls by corals. Results of these surveys are to be reported
to EPD and AFCD and will form the basis for deciding whether any further
mitigation measures are necessary.
Marine Mammals
8.9.5
Construction-phase dolphin/porpoise monitoring should
be conducted by a qualified research team, to evaluate whether there have been
any effects on the animals. The
resulting data should be compatible with, and should be made available for,
studies of small cetacean ecology in Hong Kong.
Operation
EM&A Requirements
General
8.9.6
Impacts of
operational activities will be monitored through on-site monitoring of water
quality parameters of discharges (Section
5). Monitoring and audit activities
designed to detect and mitigate any unacceptable impacts to water quality will
serve to protect against unacceptable impacts to marine ecological resources. The discharge monitoring programme (Section 5) will provide management
actions and supplemental mitigation measures to be employed should impacts
arise, thereby ensuring the operational acceptability of the Projects. As no unacceptable impacts to marine
ecological resources are predicted to occur, the development and implementation
of a monitoring and audit programme specifically designed to assess the effects
of operational activities on marine ecological resources is not deemed
necessary.
Marine Mammals
8.9.7
Operation-phase
dolphin/porpoise monitoring should be conducted for a period of two years on
commencement of operations of the cross boundary ferry terminal by a qualified
research team, to evaluate whether there have been any effects on the
animals. The resulting data should be
compatible with, and should be made available for, studies of small cetacean
ecology in Hong Kong.
8.10.1
Literature
reviews of existing information supplemented with the results of recently
undertaken field surveys on marine ecological resources indicate that the
intertidal rocky shores within the Study Area are of medium ecological value
whereas for the sandy habitats, low ecological value was assigned. Soft bottom habitats identified in the
review were regarded as of low ecological value. A small area containing high ecological value assemblages of hard
corals will be lost as a result of the reclamation activities. Information on baseline conditions suggests that
no species of conservation importance have been recorded from the marine areas
close to the reclamation site, with the exception of the Indo-Pacific
Humpbacked Dolphin. However, the waters
near the proposed reclamation sites do not appear to be highly utilised by the
dolphins, it is unlikely that this area contains critical Sousa chinensis habitat.
8.10.2
Potential
impacts to marine ecological resources from the proposed construction works may
arise either indirectly, eg through perturbations of the surrounding water
quality, or directly as a result of habitat loss. The natural intertidal and subtidal assemblages with the various
reclamation footprints will be lost permanently. However, it is anticipated that given adequate seawall design,
assemblages typical of those lost will recolonise after reclamation. Indirect impacts during the reclamation
process, such as an increase in SS levels and decrease in DO in the water
column may impact intertidal and subtidal filter feeders and other marine
organisms. However, the effects are not
expected to be severe and no unacceptable impacts are predicted to occur.
8.10.3
Operational
impacts to marine ecological resources may occur through disturbances to water
quality due to changes in the hydrodynamic regime of the area or due to
polluted discharges into the marine environment. It is expected that all discharges will comply with the WPCO discharge standards and
consequently marine ecological resources will be protected from impacts. Minor changes in the local hydrodynamic
regime are predicted although these are not expected to alter water quality to
an extent that marine ecological resources are affected. An increase in the number of vessels
travelling to and from the Pearl River Delta and the NLDFS is predicted to
occur. Many of these vessels are
expected to be high speed ferries which could potentially impact dolphin
populations. Mitigation measures have
been recommended which should minimise disturbances to dolphins.
8.10.4
Mitigation
measures specific to marine ecology include the provision of rubble
mound/armour rock seawalls on the edges of the reclamations to facilitate
colonisation by intertidal organisms and corals which will be lost as a result
of the construction of the reclamation.
Mitigation measures designed to minimise impacts to the seasonal
population of marine mammals that use the area include restrictions on vessel
speed and the use of bubble curtains during percussive piling work for
construction of the cross boundary ferry terminal and Road P1. Other mitigation measures designed to
mitigate impacts to water quality to acceptable levels (compliance with WQOs)
are also expected to mitigate impacts to marine ecological resources.
8.10.5
The impacts
occurring as a result of construction and operation of the NLDFS are the direct
loss of 258 ha of the low ecological value soft benthic assemblages, 4.6 km of
medium and low ecological value intertidal shores and 0.16 ha of high
ecological value coral habitat. The
loss of the habitat within the areas to be reclaimed can be mitigated through
the provision of 11.3 km of rubble mound/rock or concrete armour sloping
seawalls which are suitable for the colonisation and growth of intertidal
organisms. These seawalls will provide
3.1 ha which are suitable for the colonisation and growth of corals. This mitigation measure reduces the
magnitude of the residual impact to acceptable levels.
8.10.6
The
cumulative losses of habitats as a result of NLDFS, Theme Park and its
associated developments and Route 10 are the direct loss of 558 ha of soft
bottom benthic habitat, the severity of which is anticipated to be acceptable
as the areas to be reclaimed are of low ecological value. The residual impact is considered to be
acceptable as the habitat is of low ecological value and the rubble mound/rock
or concrete armour seawalls and Artificial Reefs to be deployed will assist in
enhancing the marine ecology of the area surrounding the completed
reclamations. The direct loss of 0.458
ha of subtidal hard surface habitats of high ecological value is unlikely to be
acceptable without mitigation. The
provision of rubble mound/rock or concrete armour sloping seawalls is expected
to provide greater than 7.4 ha of habitat suitable for colonisation by
corals. With these mitigation measures
in place the residual cumulative loss of subtidal habitat is considered to be
acceptable. The direct loss of 4.68 km
of natural and 4.27 km of artificial intertidal habitats, the severity of which
is anticipated to be acceptable in the light of the provisioning of greater
than 15.2 km of sloping artificial seawalls that are ecologically enhancing.
8.10.7
An
ecological monitoring and audit programme involving the use of dive surveys
will be conducted to report on the progress of colonisation of the rubble
mound/rock or concrete armour seawalls once construction works have
ceased. As an additional habitat
enhancement measure the project proponent of the Theme Park EIA has undertaken
to deploy Artificial Reefs in Hong Kong waters at a site (or sites) to be
decided upon consultation with AFCD and others. Construction-phase dolphin monitoring
should be conducted to evaluate whether there have been any effects on the
animals. Further monitoring and audit activities specifically
designed to assess the effects of the reclamation activities on marine
ecological resources are not deemed necessary as those conducted to detect and
mitigate any unacceptable impacts to water quality (see Section 5) will serve to protect against unacceptable impacts to
marine ecological resources.
Operation-phase dolphin monitoring should be conducted for a period of
two years on commencement of operations of the cross boundary ferry terminal by
a qualified research team, to evaluate whether there have been any effects on
the animals.
8.11.1
The
potential marine ecological impacts due to construction and operation of the
proposed NLDFS reclamations and developments are summarised in Table 8.11a.
Table
8.11a - Marine Ecology Impact Summary
|
Impacts
|
Summary
|
|
Sensitive
Receiver(s)
|
·
Habitat for the Indo-pacific Humpbacked
Dolphin in the coastal waters of North, Northeast and East Lantau.
·
Assumed high ecological value hard coral
assemblages located at Sze Pak Wan.
·
Medium ecological values hard coral
assemblages located on Kau Yi Chau.
|
|
Assessment Criteria
|
·
For indirect impacts compliance with the water
quality objectives. For sediment
deposition a criterion of 0.2 kg m-2 day-1 is used.
|
|
Direct Habitat Loss
for NLDFS
|
·
The loss of 4.6 km of intertidal habitats
which are of low to medium ecological value.
The residual impact is considered to be acceptable as the loss of
these organisms will be compensated by the provision of 11.3 km of sloping
rubble mound/rock or concrete armour seawalls that have been demonstrated to
become recolonised by assemblages of similar nature after construction;
·
The loss of 0.5 ha of mangrove and 2.5 ha of
mudflat of low ecological value. The residual impact is considered to be
acceptable as the habitat is of low ecological value.
·
The loss of 0.16 ha subtidal hard surface
habitats which are of high ecological value.
The residual impact is considered to be acceptable as the loss of
these organisms is compensated by the provision of seawalls (providing 3.1 ha
of habitat) that have been demonstrated to become recolonised by assemblages
of similar nature after construction; and,
·
The loss of 258 ha of the subtidal soft bottom
assemblages within the reclamation sites.
The residual impact is considered to be acceptable as the habitat is
of low ecological value and the rubble mound/rock or concrete armour seawalls
and Artificial Reefs to be deployed (see below) will assist in enhancing the
marine ecology of the area surrounding the completed reclamations.
|
|
Direct Habitat Loss
for NLDFS, Theme Park and Route 10
|
·
The direct loss of 558 ha of soft bottom
benthic habitat, the severity of which is anticipated to be acceptable as the
areas to be reclaimed are of low ecological value. The residual impact is considered to be acceptable as the
habitat is of low ecological value and the rubble mound/rock or concrete
armour seawalls and Artificial Reefs to be deployed (see below) will assist
in enhancing the marine ecology of the area surrounding the completed
reclamations.
·
The direct loss of 0.458 ha of subtidal hard
surface habitats of high ecological value is unlikely to be acceptable
without mitigation. The provision of
rubble mound/rock or concrete armour sloping seawalls is expected to provide
greater than 7.4 ha of habitat suitable for colonisation by corals. With these mitigation measures in place
the residual cumulative loss of subtidal habitat is considered to be
acceptable.
·
The direct loss of 4.68 km of natural and 4.27
km of artificial intertidal habitats, the severity of which is anticipated to
be acceptable in the light of the provisioning of greater than 15.2 km of
sloping artificial seawalls that are ecologically enhancing.
|