Pacific Coastal Biome
421
only by a small fraction: 155 g C m
−2 y
−1 in the plume and 144 g C m
−2 y
−1 on the
open shelf. At coastal stations, Skeletonema dominated phytoplankton biomass, and at
midshelf it was Synechococcus and Pseudoselenia calcar-avis, whereas at the outermost
stations where biomass is very reduced, Trichodesmium dominated. This last is a very
important contributor to productivity in the southern part of the East China Sea, where
earlier investigations (Chang, 2000) showed N-fixation rates of up to 60 M N m
−2 d
−1
from cell concentrations of >10
7 trichomes m
−2 . In spring, highest concentrations occur
near the shelf break, in autumn they are nearer the coastline. Here, the distribution of
Synechococcus is strongly seasonal: in winter, these cells are evenly distributed on the
shelf, whereas the highest concentrations in summer are at midshelf and in autumn at
the shelf edge; distribution of heterotrophic ciliates closely matches that of cyanobacterial
cells.
In coastal upwelling in the East China Sea (Chen et al., 2004), nitrate-based new
production formed about one-third of the daily production of < 45 g C m
−2 d
−1 , this
being about four times the rate in adjacent stratified shelf water where nitrate was
undetectable. This process is very dependent on the phosphate that is upwelled from
deep shelf water into the relatively phosphate-deficient river plume water. In the southern
part of the same region, Chen (2000) recorded a somewhat different relative distribution
of picoplankton. The Kuroshio water at the shelf edge had the lowest productivity
(<061 g C m
−2 d
−1 ) and the highest dominance of <3-m picoplankton (<85% of total
biomass and productivity). Although the larger fractions contributed more in coastal
upwelling regions, picoplankton were still very important in the whole.
Uye (2000) asks why the large shelf-dominant Calanus sinicus should be restricted to
the outer shelf waters in this region, and answers his own question in the following way:
everywhere, the Kuroshio water mass that lies beyond the shelf edge is too warm for
this temperate-zone species and suitable food particles are too dilute there. In the coastal
regions, there is insufficient depth for adults to perform their habitual diel migration
pattern and it is thought that developing eggs would sink to the bottom prior to hatching,
there to be lost to the population. Additionally, as elsewhere, the inner shelf mesozooplankton is dominated by small competitors—Paracalanus, Oithona, Acartia, and so on.
For such reasons, the habitat of Calanus sinicus is restricted to middle and outer shelf
regions where, indeed, it is one of the dominant herbivores.
Mesozooplankton biomass increases by a factor of about 2 in summer, and C. sinicus
and E. pacifica were the principal source of food for the large stock of Pacific herring that
inhabited the Yellow Sea until it was fished out during the 1980s. A study of the longterm response of zooplankton to between-year environmental changes (Rebstock and
Kang, 2003) on the three coasts of Korea found a common response in the abundance of
the dominant zooplankton species to the climatic regime shift of 1989: temperature and
zooplankton abundance increased subsequently in each of specific regions. Abundance
of amphipods, chaetognaths, and euphausiids increased elsewhere, but not in the Yellow
Sea. This study suggested that the ecosystem of the Yellow Sea differs strongly from
the Japan and East China Seas, perhaps because of the partially closed nature of its
circulation.
Regional Benthic and Demersal Ecology
For higher trophic levels, it is difficult or impossible today to suggest what was the nature
of the pristine ecosystem: the human population pressure is such here that the natural
resource base is stretched very thin indeed. During the past three decades, fish stocks
have become extremely stressed and the entire region subject to unrestrained pollution:
effects of oil spills and heavy metal contamination are widespread in coastal areas. The
species rank order, their diversity, and the abundance of demersal fish stocks changed
421
only by a small fraction: 155 g C m
−2 y
−1 in the plume and 144 g C m
−2 y
−1 on the
open shelf. At coastal stations, Skeletonema dominated phytoplankton biomass, and at
midshelf it was Synechococcus and Pseudoselenia calcar-avis, whereas at the outermost
stations where biomass is very reduced, Trichodesmium dominated. This last is a very
important contributor to productivity in the southern part of the East China Sea, where
earlier investigations (Chang, 2000) showed N-fixation rates of up to 60 M N m
−2 d
−1
from cell concentrations of >10
7 trichomes m
−2 . In spring, highest concentrations occur
near the shelf break, in autumn they are nearer the coastline. Here, the distribution of
Synechococcus is strongly seasonal: in winter, these cells are evenly distributed on the
shelf, whereas the highest concentrations in summer are at midshelf and in autumn at
the shelf edge; distribution of heterotrophic ciliates closely matches that of cyanobacterial
cells.
In coastal upwelling in the East China Sea (Chen et al., 2004), nitrate-based new
production formed about one-third of the daily production of < 45 g C m
−2 d
−1 , this
being about four times the rate in adjacent stratified shelf water where nitrate was
undetectable. This process is very dependent on the phosphate that is upwelled from
deep shelf water into the relatively phosphate-deficient river plume water. In the southern
part of the same region, Chen (2000) recorded a somewhat different relative distribution
of picoplankton. The Kuroshio water at the shelf edge had the lowest productivity
(<061 g C m
−2 d
−1 ) and the highest dominance of <3-m picoplankton (<85% of total
biomass and productivity). Although the larger fractions contributed more in coastal
upwelling regions, picoplankton were still very important in the whole.
Uye (2000) asks why the large shelf-dominant Calanus sinicus should be restricted to
the outer shelf waters in this region, and answers his own question in the following way:
everywhere, the Kuroshio water mass that lies beyond the shelf edge is too warm for
this temperate-zone species and suitable food particles are too dilute there. In the coastal
regions, there is insufficient depth for adults to perform their habitual diel migration
pattern and it is thought that developing eggs would sink to the bottom prior to hatching,
there to be lost to the population. Additionally, as elsewhere, the inner shelf mesozooplankton is dominated by small competitors—Paracalanus, Oithona, Acartia, and so on.
For such reasons, the habitat of Calanus sinicus is restricted to middle and outer shelf
regions where, indeed, it is one of the dominant herbivores.
Mesozooplankton biomass increases by a factor of about 2 in summer, and C. sinicus
and E. pacifica were the principal source of food for the large stock of Pacific herring that
inhabited the Yellow Sea until it was fished out during the 1980s. A study of the longterm response of zooplankton to between-year environmental changes (Rebstock and
Kang, 2003) on the three coasts of Korea found a common response in the abundance of
the dominant zooplankton species to the climatic regime shift of 1989: temperature and
zooplankton abundance increased subsequently in each of specific regions. Abundance
of amphipods, chaetognaths, and euphausiids increased elsewhere, but not in the Yellow
Sea. This study suggested that the ecosystem of the Yellow Sea differs strongly from
the Japan and East China Seas, perhaps because of the partially closed nature of its
circulation.
Regional Benthic and Demersal Ecology
For higher trophic levels, it is difficult or impossible today to suggest what was the nature
of the pristine ecosystem: the human population pressure is such here that the natural
resource base is stretched very thin indeed. During the past three decades, fish stocks
have become extremely stressed and the entire region subject to unrestrained pollution:
effects of oil spills and heavy metal contamination are widespread in coastal areas. The
species rank order, their diversity, and the abundance of demersal fish stocks changed