The Peruvian Coastal Upwelling System
233
returned as ammonium and urea by the near-bottom flow towards nearshore areas (Barber and Smith 1981). Surface nutrients values tend to be
lower off the Chilean coast and fluctuation of nitrate concentrations are
associated with El Nino events (Chavez et al. 1989). In shallow areas along
the central Peruvian coast, smelly "milky waters" or "white tides" are associated with abundant hydrogen sulfide and dissolved nitrite in the water
column, due to lack of incorporation of elevated primary production into
the pelagic food chains rather than to organic pollution.
16.3 Community Structure and Dynamics
As a result of a thermal barrier to the north and the distance of the northern limit of the Magellan Province, marine biota of the Peruvian Province shows a high degree of endemism. In general, coastal upwelling
communities are characterized by low diversity. However, strong El Nino
events introduce numerous species from the open ocean and the Panamanian Province, thus species richness can be considerable (Tarazona and
Valle 1999).
16.3.1 Phytoplankton
The phytoplankton community (168 diatoms, 209 dinoflagellates) is dominated by cosmopolitan species, though some species are indicators of
specific water masses. In shallow waters pennate diatoms are most conspicuous (i.e., Cocconeis sp., Licmophora abbreviata, Grammatophora marina,
Navicula membranacea, Pleurosigma elongatum). In the Peru Coastal Current small diatoms (i.e., Skeletonema costa tum, Actinocyclus octonarius,
Lithodesmium undulatum, Chaetoceros affinis, Thalassiosira subtilis) and
elevated reproduction rates prevail. Subtropical surface water of the
Oceanic Province is dominated by dinoflagellates ( Ceratocorys horrida, C.
trichoceros, C. hexacanthum f. sirale, C. gravidum) and some large diatoms
( Chaetoceros radicans, Rhizosolenia temperei, Planktoniella sol). Coastal
upwelling areas are characterized by the dominance of chain-forming,
colonial diatoms (5-30 !J.m) with high division rates, which use recently
upwelled nutrients more effectively than pica- and nanoplankton. Phytoplankton primary production (3.84 mg C m- 2 day- 1 ) and bacterioplankton
biomass (up to 4.05 g C m- 2 ) of the Peruvian coastal upwelling ecosystem
are fueled by the supply of additional nutrients, though silicates may be a
limiting factor.
233
returned as ammonium and urea by the near-bottom flow towards nearshore areas (Barber and Smith 1981). Surface nutrients values tend to be
lower off the Chilean coast and fluctuation of nitrate concentrations are
associated with El Nino events (Chavez et al. 1989). In shallow areas along
the central Peruvian coast, smelly "milky waters" or "white tides" are associated with abundant hydrogen sulfide and dissolved nitrite in the water
column, due to lack of incorporation of elevated primary production into
the pelagic food chains rather than to organic pollution.
16.3 Community Structure and Dynamics
As a result of a thermal barrier to the north and the distance of the northern limit of the Magellan Province, marine biota of the Peruvian Province shows a high degree of endemism. In general, coastal upwelling
communities are characterized by low diversity. However, strong El Nino
events introduce numerous species from the open ocean and the Panamanian Province, thus species richness can be considerable (Tarazona and
Valle 1999).
16.3.1 Phytoplankton
The phytoplankton community (168 diatoms, 209 dinoflagellates) is dominated by cosmopolitan species, though some species are indicators of
specific water masses. In shallow waters pennate diatoms are most conspicuous (i.e., Cocconeis sp., Licmophora abbreviata, Grammatophora marina,
Navicula membranacea, Pleurosigma elongatum). In the Peru Coastal Current small diatoms (i.e., Skeletonema costa tum, Actinocyclus octonarius,
Lithodesmium undulatum, Chaetoceros affinis, Thalassiosira subtilis) and
elevated reproduction rates prevail. Subtropical surface water of the
Oceanic Province is dominated by dinoflagellates ( Ceratocorys horrida, C.
trichoceros, C. hexacanthum f. sirale, C. gravidum) and some large diatoms
( Chaetoceros radicans, Rhizosolenia temperei, Planktoniella sol). Coastal
upwelling areas are characterized by the dominance of chain-forming,
colonial diatoms (5-30 !J.m) with high division rates, which use recently
upwelled nutrients more effectively than pica- and nanoplankton. Phytoplankton primary production (3.84 mg C m- 2 day- 1 ) and bacterioplankton
biomass (up to 4.05 g C m- 2 ) of the Peruvian coastal upwelling ecosystem
are fueled by the supply of additional nutrients, though silicates may be a
limiting factor.