Biodiversity of
China¡¯s seas, coasts and islands
1 Species
diversity of China¡¯s seas
2 Ecosystem
diversity of China¡¯s seas
3 The
diverse coastal ecosystem
4 Ecosystem
diversity of China¡¯s islands
5 Serious
threats confronting the marine biodiversity of China¡¯s seas
6
Efforts to protect the biodiversity of China¡¯s seas, coasts and islands
1
Species diversity of China¡¯s
seas
The 20,278
species of organisms recorded from China¡¯s seas belong to 5 kingdoms and 44
phyla. Of these, the Animalia includes 24 phyla, the most abundant species of
which are the Arthropoda, Mollusca and Chordata with more than 2,500 species
each. Of the six plant phyla, three are algae with 794 species and three are
vascular plants with 413 species. Seven phyla of the Protista have nearly 5,000
species (Table 1).
Of the 24
animal phyla, 10 are exclusively marine. The number of species is more than in
freshwaters but less than on land. Species numbers increase toward the south.
China¡¯s seas encompass both the southern boundary of many temperate species and
the northern boundary of many tropical ones.
Table 1 The numbers of species recorded from China¡¯s
seas
|
Kingdom
and phylun |
Kingdom
and phylum |
Kingdom
and phylum |
|||
|
MONERA |
229 |
PLANTAE |
1,203 |
|
|
|
Bacteria |
79 |
Rhodophyta |
443 |
Priapulida |
2 |
|
Actinobacteria |
18 |
Phaeophyta |
153 |
Annelida |
979 |
|
Cyanomyceta |
131 |
Chlorophyta |
194 |
Sipuncula |
39 |
|
Prochlorophyta |
1 |
Pteridophyta |
11 |
Echiura |
9 |
|
PROTISTA |
4956 |
Gymnospermae |
3 |
Mollusca |
2554 |
|
Bacillariophyta |
1395 |
Angiospermae |
399 |
Arthropoda |
29 |
|
Pyrrophyta |
255 |
ANIMALIA |
12794 |
Bryozoa |
488 |
|
Chrysophyta |
14 |
Porifera |
106 |
Entoprocta |
9 |
|
Xanthophyta |
3 |
Coelenterata |
989 |
Brachiopoda |
8 |
|
Cryptophyta |
1 |
Ctenophora |
9 |
Phoronida |
4 |
|
Ciliophora |
291 |
Platyhelminthes |
574 |
Chaetognatha |
37 |
|
Sarcomastigophora |
2997 |
Nemertea |
52 |
Echinodermata |
471 |
|
FUNGI |
188 |
Kinorhyncha |
10 |
Hemichordata |
6 |
|
Yeast |
61 |
Nematoda |
122 |
Urochordata |
125 |
|
Other
fungi |
127 |
Acanthocephala |
32 |
vertebrata |
3181 |
|
Mycophycophyta |
1 |
Rotifera |
17 |
|
|
2
Ecosystem diversity of
China¡¯s seas
Bordering
mainland China are the Bohai Sea, the Yellow Sea, the East China Sea and the
South China Sea with collective areas of 4.73 million km2. The
Yellow Sea and Bohai Sea are situated on the boundary of the north temperate
region, and the East China Sea and South China Sea are in the subtropics. Each
exhibits the characteristics of a large marine ecosystem. The Kuroshio Current,
estuarine waters and up-welling areas in China¡¯s neritic seas also show
ecosystem level biodiversity.
(1) The Bohai Sea
The Bohai
Sea is an inland sea on the mainland coast of China with an area of 80,000 km2,
a maximum depth of 70m and an average depth of 18m.
A total of
120 species of phytoplankton, dominated by eurythermal, low salinity, diatom
species, have been recorded from the Bohai Sea. The dominant species are
representative of the Coscinodiscacus, Chaetoceros, Rhizosolenia and Skeletonema costatum. There are also about 100 species of zooplankton,
dominated by temperate low salinity and some oceanic species. The dominant
species are Noctiluca scientillans,
Calanus sinicus, Paracalanus parvus,
Labidocera euchaeta, and Sagitta
crasse. More than 100 species of benthic plants mainly warm temperate
species with green algae dominant in the inter-tidal zone and brown and red
algae dominant in subtidal zones, have been recorded. There are about 140
species of benthic animals which are also dominated by low salinity species. Of
these, the species with a larger biomass and commercial fishing value are Scapharca subcrenata,
Ruditapes philippinarum, Meretrix meretrix,
Ostrea plicatula, Penaeus chinensis and Exopalaemon carinicauda.
There are about 120 species of nekton, most of which are fishes, plus a few
shrimps, crabs, squids and marine mammals. There are abort 20 main species of
fish, such as Setipinna taty, Engraulis japonicus, Lateolabrax japonicus, Nibea albilora and Cynoglossus semilaevis.
(2) The Yellow Sea
The Yellow
Sea is a semi-enclosed shallow continental sea with an area of 380,000 km2,
a mean depth of 44 m and a maximum depth of 140m. The circulation of the Yellow
Sea is mainly influenced by the Yellow Sea Warm Current and coastal currents.
Its continental shelf is mainly covered by pelitic and silty deposits. As it is
located in the northern temperate zone, a unique biota which is characterized
by an assemblage of elements from frigid, subfrigid, tropical and subtropical
areas, in addition to native species.
A total of
386 species of phytoplankton have been recorded from the Yellow Sea which is
dominated by representatives of the Coscinodiscacus,
Biddulphia, Chaetoceros, Rhizosolenia,
Nitzschia and Peridinium,
with a variety of ecologies indicative of temperate seas.
A total of
130 species of zooplankton has been recorded. They are either warm temperate
neritic species, typical of coastal currents, or warm water species from the
Kuroshio. The dominant species are Calanus
sinicus, Centropages memurrichi,
Euphausia pacifica, Parathemisto gracilipes and Sagitta crassa.
Some 200
species of benthos have been recorded. Of these, the Polychaeta is the most
numerous followed by the Mollusca, Crustacea and Echinodermata. There are also
some widely distributed species such as Sternaspis
scutata, Nereis longior, Eucymene annandalei,
Ceratonereis erythraeenis, Tambalagmia fauveli,
Leptochela gracilis, Amphioplus ancistrotus and Ophiura sarsii.
A total of 219 and 225 species
of nekton have been recorded from the northern and the southern Yellow Sea,
respectively. Fish are the most common species; together with shrimps, crabs,
and squids. The most dominant species include Clupanodon punctatus,
Setipinna taty, Harengula zundsi, Sardinella sp., Stromateoides argenteus,
Ilisha elongatea, Cynoglossus semilaevis, Pseudodiaena polyactis, Nibea albiflora, Trichiurus haumela,
Lateolabrax japonicus and Paralichthys
olovaceus. There are, in
addition, 15 species of whales, three pinnipedes and four turtles in the Yellow
Sea.
(3) The East China Sea
The East
China Sea has an area of 770 km2 and a mean depth of 370 m over the
continental shelf and a maximum depth of 2,719 m at the bottom of the
continental slope. Coastal currents and the Taiwan Warm Current are important
in the shallow waters of this sea.
A total of
64 species of phytoplankton occur in the waters near the estuary of the Yangtze
River and 261 species occur off-shore in Zhejiang. The dominant algae are Skeletonema costatum, Coscinodiscacus spp., Chaetoceros lauderi and Nitzschia pungens. Neritic temperate species are the most common ecological type.
A total of
81 species of zooplankton occur close to the Yangtze River estuary and 223
species have been recorded from the coast of Zhejiang. Peaks in biomass occur
in the summer. The main species are Calanus
sinicus, Labidocera euchaeta, Pseudeuphausia sinica, Acartia pacifica and Sagitta enflata.
A total of
342 species of benthos have been recorded from the East China Sea. The Mollusca
account for 77, the Polycheata 77, the Crustacea 95, the Echinodermata 136, the
fishes 62, with 18 others.
There are
167 fishes recorded from the Yangtze River Estuary and shallow waters of the
East China Sea. Of 203 species of nekton in the shallow waters of Zhejiang,
common species of fish include Pseudosciaena
crucea, Trichiarus haumela, Ilisha elongata, Stromateoides argenteus,
Harpodon nekereus, Miichthys miiry, Muraenesox cinereus and Acetes chinensis. Other species include Exopalaemon
carinicauda, Portunus trituberculatus, Charybdis japonica and Sepiella maindroni.
(4) The South China Sea
The South
China Sea encompasses tropical and subtropical zones. It is a semi-enclosed sea
with a continental margin and an area of 3.5 million km2. There is a
wide continental shelf, and 30% of the waters are deep with a mean depth of 1.4
km. Two main currents, a coastal current and the South China Sea Warm Current,
occur in the northern South China Sea.
The number
of phytoplankton species differs between regions and ranges from 104 to 260.
They belong to two large groups, the diatoms and dinoflagellates, of which Chaetoceros and Rhizosolenia are dominant.
In the
offshore waters of the northern and southern South China Sea, 130 and 250
species of zooplankton have been recorded, respectively, and of which the main
ones are copepods. Zooplankton biomass forms a single peak over the course of
each year.
Benthic
organisms in the estuarine waters of the coast of Guangdong comprise 319
species most of which are tolerant of low salinities and occur in high numbers.
In contrast, the benthos of the middle and western region of eastern Guangdong
and the coastal waters of western Guangdong mostly comprise species with a high
salinity tolerance, typical of the southern subtropics and tropics. A total of
820 species are dominated by the Mollusca, Arthropoda and Annelida. Most of the
benthos along the coast of Hainan comprises tropical species, with a total of
755, dominated by corals, algae, molluscs and echinoderms. A total of 832
species recorded from along the coast of Guangxi are dominated by Turritella bacillum and Scapharca subcrenata. Of 135 species of benthos recorded from
the Xisha Islands, 30.37% are crustaceans and the rest are mainly molluscs and
echinoderms.
The nekton
recorded from the northern South China Sea comprises 1,064 species, of which
100 are economically important, such as Decapterus
maruadsi, Sardinella aurita,
Pneumatophorus japonicus and Trachurus
japonicus. It has been recorded that there are
here some 200 species of shrimps belonging to Penaeus, Metapenaeopsis and Metapenaeus. Most of
these are tropical and subtropical. The fishes comprise 535 species, and
shrimps in the South China Sea are not characterized by dominant species. There
are 58 species of cephalopod, of which 25 species, such as Todarodes pacificus, Nototodarus
hawaiiensis and Sepiella sepia are
of commercial value. Dominant species in the southern South China Sea are coral
reef fishes and tropical oceanic fishes.
(5) The Kuroshio
The
Kuroshio is the largest current passing along the continental shelf of China.
As one of the strongest currents in the world, this hot water flow has a great
influence on the shallow seas of China¡¯s continental shelf. Based on the
results of a survey of the current by Chinese scientists and a co-operative
survey between China and Japan, 419 species of phytoplankton, 697 species of
zooplankton, more than 180 larval and young fishes and 2,000 species of nekton
have been identified from it.
Kuroshio
organisms belong to different ecological groups. For example, the phytoplankton
may include high thermohaline, low salinity and high thermophile, high salinity
and low thermophile, and eurythermohaline species. Zooplankton may include warm
temperate neritic and tropical oceanic species. Fishes may include pelagic,
meso-pelagic and benthic species.
As is
typical of high thermohaline waters, the Kuroshio can be detected by its
indicator species, for example, phytoplankton such as Gossleriella tropica, Asterolampra marylandica,
Cheatoceros dadayi, Ceratocorys bipes and Amphisolenia shauinslandi.
More than twenty zooplankton species, such as Euchaeta concinna, E. marina, Pareuchatea russelli,
Sagitta enflata, Liriope tetraphylla,
Pseudoconchoecia concentrica, and Euphausia
tenera, can also be used as indicators of the current.
(6) Estuaries
There
are more than 1,500 rivers and streams draining into the seas along the coast
of China. The huge input of freshwater and terrigenous material creates an
unique estuarine ecosystem. In general, the species composition of an estuary
is complicated and highly diversified. This can be demonstrated by reference to
the species composition of three estuaries, i. e., the species of phytoplankton
in the Pearl River, the Yangtze River, and the Yellow River estuaries are
64,103 and 224, respectively; the corresponding numbers of zooplankton are
105,66 and 133, benthos are 153,191 and 456, intertidal zone species are 41,195
and 189, and nekton are 189,144 and 356, again respectively.
The
ecological types in these estuaries are different, e. g., the Pearl River
Estuary is dominated by tropical and subtropical species with warm-water
species as dominant nekton and the Yangtze River and Yellow River estuaries by
cosmopolitan and temperate species with warm-temperate species as dominant
nekton.
In spite of
different ecological types, the uniqueness of the estuarine environment results
in a similar community structure, i. e., they can all be divided into 3
categories: freshwater, brackish water, and marine water communities. For
example, the composition of the fish fauna in the Yangtze River Estuary
comprises: (1) 17.4% freshwater species mainly of the Cyprinidae and Cobitidae;
(2) 21.6% brackish water species mainly of the Mugilidae and Gobiidae and (3)
57.2% marine water species mainly of the Clupeiformes, Beloniformes,
Perciformes and Pleuronectiformes.
(7) Upwelling ecosystems
There are
many up-welling areas in China¡¯s seas, e. g., in the middle of the Bohai Sea
the cold waters of the Yellow Sea, off-shore from the Shangdong Peninsula and
Zhejiang the nearshore waters of southern Fujian, southwest of Taiwan, the
nearshore waters of eastern Guangdong and along the southeast coast of Hainan.
Some examples are as follows:
The
offshore area in southern Fujian. Centered on the Nanpeng Archipelago, the
upwelling area ranges from the Lishi Archipelago in Zhangpu, Fujian, to the
Jiazj waters of Guangdong. In comparison to the open sea in summer, it is
characterized by low temperature (2~4¡æ
lower than that of open sea), high salinity (some 0.5¡ë~1.5¡ë higher), low
dissolved oxygen levels (<4.4 ml/L) low oxygen saturation (<90%) and high
nutrient levels (N+ 13.8 µmol/L, P+ 0.4 µmol/L). Pareuchaeta russelli, Euconchoecia maimai and Dolioletta gegenbauri are indicators of
this upwelling water and appear in great numbers. The bacterial biomass may
peak at 66.6 µg C/m3 and is dominated by coldwater luminescent
species. In addition, phytoplankton density is high (>108 cells/m3),
with a high primary productivity [1.06g C/(m2¡¤d)] and a total zooplankton biomass of
more than 250 mg/m2. Up-welling is a kind of wind-driven ascending
current, i. e., a compensation current from the bottom water as a result of the
southwestern land breeze occurring only in summer. Consequently, the fishing
ground also only exists in summer.
The
southern Taiwan Shoal. There exists, almost year round, a narrow band of low
temperature, high salinity and high density water oriented in an east-west
direction. The rapidly ascending isopleth trend in terms of temperature and
salinity along the continental slope demonstrates the existence of a low pH
centre and a surge of bottom water with high nutrient levels and low oxygen
saturation. The indicator species, Calanoides
carinatus, is found year round as
is Callinitra emmae which comes from
a depth of 5,000 m. High densities of eggs, larvae and young fishes, of which
9% are from the deep sea, enter this area. The upwelling climbs up with the
bottom current along the slope, with the help of wind action in addition to the
circulation pattern around the Taiwan Shoals. This upwelling is, thus, mainly
topography-induced. Due to the permanent existence of upwelling in the area, a
major fishing ground is present on the southern Taiwan Shoal year round.
Upwelling,
as a special hydrological phenomenon, results in a special ecosystem. An
upwelling ecosystem is generally characterized by its high productivity, a
short food chain, a fast nutrient cycle and efficient energy transfer.
3
The diverse coastal
ecosystem
(1) Intertidal ecosystems
According
to an intertidal zone survey conducted during the period from 1981 to 1986, a
total of 1,590 species, but probably several times that figure in practice, has
been recorded from the shores of China. The number of species increases towards
the south, i. e., it starts at 251 species in the Bohai Sea and reaches more
than 971 in the South China Sea (Table 2). Except for those dominant
eurythermal, euryhaline and cosmopolitan species, some are typical of temperate
waters, such as Chthamalus challengeri, Stenothyra glabar and Styela clava, whereas others are typical tropical and subtropical species such
as Euraphia witherisi, Nodilittorina trochoides and Styela plicata. The species on hard
substrata of reefs and piles are different from species on soft bottoms of sand
and mud.
Table 2 The numbers of intertidal species along
the coast of China (1981-1986)
|
|
Bohai
Sea |
Yellow
Sea |
East
China Sea |
South
China Sea |
Total |
|
Cnidaria |
6 |
12 |
9 |
22 |
38 |
|
Polychaeta |
45 |
101 |
142 |
78 |
218 |
|
Mollusca |
83 |
180 |
296 |
335 |
513 |
|
Crustacea |
54 |
116 |
196 |
202 |
308 |
|
Echinodermata |
8 |
22 |
30 |
54 |
78 |
|
Pisces |
17 |
12 |
35 |
40 |
61 |
|
Algae |
34 |
147 |
97 |
235 |
358 |
|
Others |
4 |
15 |
6 |
5 |
16 |
|
Total |
251 |
605 |
811 |
971 |
1590 |
The
weight and diversity of the benthic biomass varies much between areas and
sediment types, e. g., the wet weight of biomass in the Yellow Sea is as high
as 2.199 g/m2, compared with 217g/m2 in the East China
Sea. Density reaches 1,013 individuals/m2 in the Bohai Sea but only
317 individuals/m2 in the South China Sea. This also demonstrates
that a discrepancy exists in terms of biomass on different substrata. The
number of animals is much higher on a hard bottom than on a soft one. For
example, the biomass of a coral reef is 41 times that of a mangrove mudflat.
The same situation occurs with density. This is mostly due to the gregarious
attachment of shells, such as barnacles and oysters, on hard substrata. The
biomass of the intertidal zone is much higher than that of the shallow water
benthos, demonstrating the high productivity of the intertidal zone.
Intertidal
communities can be divided distinctly into 3 vertical zones: high, middle and
low, related to the tidal exposure of the substratum. Species numbers and
biomass are low in the high intertidal zone while they vary with location and
substratum type in the middle and lower zones. This discrepancy between tidal
zones cannot be generalized, or simply averaged. Biological zonation on a rocky
shore is, however, clear. Usually, a littorinid-lichen-barnacle zone forms on
the high intertidal. The dominant species of this zone are similar to those
which occur in the Bohai and Yellow Seas. Here it is characterized by Chthamalus challengeri but this species
does not occur in the East and South China Seas where the warm water species Nodilittorina, trochoides and Capitulum
mitella take its place. Species inhabiting the middle tidal zone include
the oyster Saccostrea sp., barnacles
and green algae. Brown algae and red algae inhabit the low intertidal zone. In
the Bohai Sea and Yellow Sea, Chthamalus
challengeri is the exclusive dominant species of this zone. In contrast,
species like Saccostrea echinata, S.
mordax, Tetraclita squamosa squamosa, and species of Ulva and Gelidium, occur
in great quanties in the East China Sea and South China Sea. Brown algae and
red algae inhabit the low intertide zone. Sargassum
pallidum is typical of the Yellow Sea. Warm water species, such as Sargassum henslowianum, Ishige okamurae, Hypnea japonica and Symphyocladia marchantioides can only be found
to the south of the East China Sea.
(2) Coastal marsh-wetland ecosystem (Boreal)
There are
many saline marshes and mudflats in estuaries to the north of Zhejiang. This
kind of wetland, i. e., a biotope covered with grass vegetation high in the
intertidal zone, mid tidal zone and supratidal zone, are mostly the habitat of
birds and make up a marsh-wetland ecosystem. Such ecosystems can be found in
the mudflats of the Yalujiang River Estuary, the Liaohe Delta, the Yellow River
Delta, Laizhouwan Bay, Tianjin Beach in Bohai Bay, Dagu Estuary in Shandong,
Yancheng Estuary in Jiangsu, Chongming Estuary of the Yangtze River, Nanhui
district of Shanghai, the beaches of Hangzhou Bay and the beaches of the
Yongjiang and Oujiang Rivers.
In marshes
connecting freshwater and estuarine areas beyond the supra-tidal zone, wide
areas of lush reeds (Phragmites communis) are distributed from the Yalujiang
Estuary in the north to Hangzhou Bay in the south. Small patches of reed bed
also occur in Guangdong. The area of reed bed in the Liaohe Delta is 67,000 ha.
Seaward of the reed bed in the high intertidal zone, vast areas of short
vegetation such as Salsola glauca and
Salicornia europaea are found. In the
high intertidal zone of the Yangtze River Estuary and Hangzhou Bay, Scirpus marigueter grows in large areas
of marsh. For example, its community of Jin Si Niang Bridge, Pin Hu, on the
northern coast of Hangzhou Bay has an area of 500¡Á3,000 m2, a height
of 20 cm and 85% cover.
Up to 1992,
the grasses Spartina anglica and S.
alterniflora introduced from England in 1963 and from America in 1979,
respectively, have grown and spread to cover 6,000 ha of the high intertidal
zone along stretches of the coast from Liaoning to Guangxi. They form an
artificial biotope, especially in Jiangsu and Zhejiang.
Table 3
lists 8 representative wetland grass communities with their relevant migrants
from the Yalujiang Estuary to Hangzhou Bay.
Table 3 Some
representative wetland grass communities and birds
along the coastal
regions of northern and middle China
|
Mud flat |
Vegetation |
Birds
recorded and species numbers |
|
|
Reed bed |
Others |
||
|
Yalujian River Estuary |
11,000 ha |
Salsola
glauca,
Salicornia europaea |
>70 species, Cygnus cygnus, Egretta
eulophots |
|
Liaohe Delta |
67,000 ha |
S. glauca, S. europaea |
|