320
S.E. Ibarra-Obando et al.
Sea urchins (Strongylocentrotus purpuratus, S. franciscanus), abalone
(Haliotis sorenseni, H. rufesens, H. fulgens, H. cracherodii) and lobsters
(Panulirus interuptus, P. injlatus, P. gracilis) find a habitat in the kelp
forests. A large number of fish, like the white seabass (Atractoscion nobilis ),
kelp bass (Paralabrax clathratus), topsmelt (Atherinops affinis), jack
mackerel (Trachurus symmetricus), kelp perch (Brachyistius frenatus),
black perch (Embiotoca jacksoni), rubberlip seaperch (Rhacochilus
toxotes), blacksmith ( Chromis punctipinnis), senorita ( Oxyjulis californica), kelp rockfish (Sebastes atrovirens), yellowtail (Seriola lalandi), and
California halibut (Paralichthys californicus), are associated with kelps.
The bat ray (Myliobatus californica) and torpedo ray (Torpedo californica)
as well as the horn shark (Heterodontus francisci) and leopard shark (Triakis semifasciata) are common in kelp habitats.
Top carnivores are represented by species with wide latitudinal distribution, such as the shortbeak common dolphin (Delphinus capensis), bottlenose dolphin (Turniops truncatus), Pacific white-sided dolphin (Lagenorynchus obliquidens ), killer whale (Orcin us orca), humpback whale
(Megaptera novaengliae), blue whale (Ballaenoptera musculus), California
sea lion (Zalophus californianus), and the harbor seal (Phoca vitulina). Sea
turtles (Eretmochelys imbricata, Lepidochelys olivacea, Chelonia mydas)
are also common and the gray whale (Eschrichtius robustus) is a regular
visitor with breeding grounds in the Laguna Ojo de Liebre and Laguna San
Ignacio during the winter.
The trophic dynamics of upwelling off Punta San Hipolito (27°N)
during two successive seasons (Walsh et al. 1977) indicate that the initial
stage of upwelling is accompanied by a transition from an oceanic
(dinoflagellate-herbivorous copepod-carnivorous red crab-striped dolphin) food chain to upwelling food chains (Walsh et al. 1974). Major components of phyto- and zooplankton are G. polyedra and the copepod
Acartia sp., while the red crab P. planipes and the Pacific white-sided
dolphin Lagenorynchus obliquidens appear to be the major carnivores,
though the role of L. obliquidens as top predator is still uncertain. Despite
similar upwelling intensity, nutrient content and phytoplankton growth
rates, the production and biomass of phytoplankton vary between
years (i.e. 1972 -8 g C m- 2 day- 1 and 1973 - 4 g C m- 2 day- 1 ), possibly in
response to grazing pressure by the red crab P. planipes. Red crabs, which
during the onset of upwelling feed at higher trophic levels, tend to move
to lower trophic levels during advanced stages of upwelling, probably following changes in phytoplankton composition from smaller dinoflagellates (G. polyedra) to larger diatoms ( Coscinodiscus excentricus). After
continued consumption and lower phytoplankton density, red crabs use
detritus as an alternate food source and could thus replace phytophagous
S.E. Ibarra-Obando et al.
Sea urchins (Strongylocentrotus purpuratus, S. franciscanus), abalone
(Haliotis sorenseni, H. rufesens, H. fulgens, H. cracherodii) and lobsters
(Panulirus interuptus, P. injlatus, P. gracilis) find a habitat in the kelp
forests. A large number of fish, like the white seabass (Atractoscion nobilis ),
kelp bass (Paralabrax clathratus), topsmelt (Atherinops affinis), jack
mackerel (Trachurus symmetricus), kelp perch (Brachyistius frenatus),
black perch (Embiotoca jacksoni), rubberlip seaperch (Rhacochilus
toxotes), blacksmith ( Chromis punctipinnis), senorita ( Oxyjulis californica), kelp rockfish (Sebastes atrovirens), yellowtail (Seriola lalandi), and
California halibut (Paralichthys californicus), are associated with kelps.
The bat ray (Myliobatus californica) and torpedo ray (Torpedo californica)
as well as the horn shark (Heterodontus francisci) and leopard shark (Triakis semifasciata) are common in kelp habitats.
Top carnivores are represented by species with wide latitudinal distribution, such as the shortbeak common dolphin (Delphinus capensis), bottlenose dolphin (Turniops truncatus), Pacific white-sided dolphin (Lagenorynchus obliquidens ), killer whale (Orcin us orca), humpback whale
(Megaptera novaengliae), blue whale (Ballaenoptera musculus), California
sea lion (Zalophus californianus), and the harbor seal (Phoca vitulina). Sea
turtles (Eretmochelys imbricata, Lepidochelys olivacea, Chelonia mydas)
are also common and the gray whale (Eschrichtius robustus) is a regular
visitor with breeding grounds in the Laguna Ojo de Liebre and Laguna San
Ignacio during the winter.
The trophic dynamics of upwelling off Punta San Hipolito (27°N)
during two successive seasons (Walsh et al. 1977) indicate that the initial
stage of upwelling is accompanied by a transition from an oceanic
(dinoflagellate-herbivorous copepod-carnivorous red crab-striped dolphin) food chain to upwelling food chains (Walsh et al. 1974). Major components of phyto- and zooplankton are G. polyedra and the copepod
Acartia sp., while the red crab P. planipes and the Pacific white-sided
dolphin Lagenorynchus obliquidens appear to be the major carnivores,
though the role of L. obliquidens as top predator is still uncertain. Despite
similar upwelling intensity, nutrient content and phytoplankton growth
rates, the production and biomass of phytoplankton vary between
years (i.e. 1972 -8 g C m- 2 day- 1 and 1973 - 4 g C m- 2 day- 1 ), possibly in
response to grazing pressure by the red crab P. planipes. Red crabs, which
during the onset of upwelling feed at higher trophic levels, tend to move
to lower trophic levels during advanced stages of upwelling, probably following changes in phytoplankton composition from smaller dinoflagellates (G. polyedra) to larger diatoms ( Coscinodiscus excentricus). After
continued consumption and lower phytoplankton density, red crabs use
detritus as an alternate food source and could thus replace phytophagous