408
Chapter 11: The Pacific Ocean
Regional Benthic and Demersal Ecology
Hermatypic corals are minor reef-forming agents in this province, in which benthic
ecology strongly resembles that of the coast of intertropical West Africa (Longhurst and
Pauly, 1987). Although we do not have for this province a survey of the quality of the
GTS (see GUIN), it appears that the same genera of demersal fish, in similar relative
proportions, occur here—or, at least, occurred in the pristine fish fauna—and that this
is very distinct from that of the western Pacific at similar latitudes: some genera that are
characteristic of that region are entirely lacking here, such as Leignathus and Lactarius.
Synopsis
Case 6—Intermittent production at coastal divergences—The pycnocline is extremely shoal
and shows very weak seasonality with some slight boreal winter mixing. Photic depth is
consistently deeper (35–45 m), so the thermocline is illuminated year-round. Regional
mean productivity rate increases rapidly to about 10 mg C m
−2 d
−1 in June, after which
progressive reduction occurs during the second half of the year, perhaps reflecting events
in the Gulfs of California, Tehuantapec, and Panama (Fig. 11.19). Chlorophyll biomass
appears to be insensitive to changes in PP rate but shows significant accumulation during
boreal spring. However, as noted earlier, it is the productivity of the Costa Rica Dome
that dominates the regionally integrated data, rather than processes at the coast. So, this
figure and the meaned data that represent this province may be somewhat misleading.
0
20
40
60
80
100
0
5
10
15
20
25
30
35
Climatology (years)
Depth (m)
Production at DCM (%)
Zm (sigma)
Zeu
Pt (at DCM)
0.00
0.25
0.50
0.75
1.00
1.25
0.00
0.30
0.60
0.90
1.20
1.50
SeaWiFS (CAMR): September 1997 - January 2002
Surface Chl (mg m -3
)
Pt d
-1
Chl m
-3
1998
1999
2000
2001
Pt (gC m
-2
d
-1
)
Fig. 11.19 CAMR: seasonal cycles of monthly surface chlorophyll and depth-integrated autotrophic production for the years 1997–2002 from SeaWiFS data together with characteristic seasonal cycles of mixed-layer
depths from Levitus climatological data and photic depths computed from characteristic irradiance and the
archive of chlorophyll profiles discussed in Chapter 1.
Chapter 11: The Pacific Ocean
Regional Benthic and Demersal Ecology
Hermatypic corals are minor reef-forming agents in this province, in which benthic
ecology strongly resembles that of the coast of intertropical West Africa (Longhurst and
Pauly, 1987). Although we do not have for this province a survey of the quality of the
GTS (see GUIN), it appears that the same genera of demersal fish, in similar relative
proportions, occur here—or, at least, occurred in the pristine fish fauna—and that this
is very distinct from that of the western Pacific at similar latitudes: some genera that are
characteristic of that region are entirely lacking here, such as Leignathus and Lactarius.
Synopsis
Case 6—Intermittent production at coastal divergences—The pycnocline is extremely shoal
and shows very weak seasonality with some slight boreal winter mixing. Photic depth is
consistently deeper (35–45 m), so the thermocline is illuminated year-round. Regional
mean productivity rate increases rapidly to about 10 mg C m
−2 d
−1 in June, after which
progressive reduction occurs during the second half of the year, perhaps reflecting events
in the Gulfs of California, Tehuantapec, and Panama (Fig. 11.19). Chlorophyll biomass
appears to be insensitive to changes in PP rate but shows significant accumulation during
boreal spring. However, as noted earlier, it is the productivity of the Costa Rica Dome
that dominates the regionally integrated data, rather than processes at the coast. So, this
figure and the meaned data that represent this province may be somewhat misleading.
0
20
40
60
80
100
0
5
10
15
20
25
30
35
Climatology (years)
Depth (m)
Production at DCM (%)
Zm (sigma)
Zeu
Pt (at DCM)
0.00
0.25
0.50
0.75
1.00
1.25
0.00
0.30
0.60
0.90
1.20
1.50
SeaWiFS (CAMR): September 1997 - January 2002
Surface Chl (mg m -3
)
Pt d
-1
Chl m
-3
1998
1999
2000
2001
Pt (gC m
-2
d
-1
)
Fig. 11.19 CAMR: seasonal cycles of monthly surface chlorophyll and depth-integrated autotrophic production for the years 1997–2002 from SeaWiFS data together with characteristic seasonal cycles of mixed-layer
depths from Levitus climatological data and photic depths computed from characteristic irradiance and the
archive of chlorophyll profiles discussed in Chapter 1.