158
C. Odebrecht and J.P. Castello
macro-zooplankton (i.e., Euphausia similis), the mesopelagic fish Maurolicus muelleri, and on squid.
The input of nutrients (mainly nitrate) through fertilization processes to
southern Brazilian shelf waters favors growth of large primary producers
(microplankton), like single centric diatoms or chains of small-celled species, chlorophyll-a nuclei, and high productivity rates (160 g C m- 2 year- 1 ;
Odebrecht and Garcia 1997). Shorter and less complex food chains are characterized by the dominance of planktophagous pelagic fish, like Engraulis
anchoita, and their predators (Merluccius hubbsi, Trichiurus lepturus,
Cynoscion guatucupa, Pagrus pagrus, Galeorhinus galeus, and the skates
Sympterigia acuta and S. bonapartei). Other zooplanktophagous species
include squids (Illex argentinus, Loligo sanpaulensis) and fishes (Anchoa
marinii, Trachurus lathami, juveniles of Cynoscion guatucupa, and Trichiurus lepturus). Over the outer shelf, pelagic zooplanktophagous species
are represented by Maurolicus muelleri, mictophyds, gonastomatids,
juvenile Merluccius hubbsi, Brama spp., Loligo sanpaulensis, Ornithoteuthis antillarum, and Illex argentinus, which also preys on small pelagic
and mesopelagic fishes. Pelagic-benthic interactions are especially important over the intermediate shelf (40-60 m) where high chlorophyll-a concentrations under the influence of SAW in winter coincide with high
demersal fish biomass (mainly sciaenids) in southern Brazilian waters
(Haimovici 1997b ).
11.6 Human Impacts
Demographic and industrial growth along the coast, fringing the warm
transition zone ecosystem in the SW Atlantic Ocean, threatens coastal
integrity. The pressure on fisheries stocks has deleterious effects on biodiversity and the sustainability of several activities. Coastal hazards, harmful algal blooms, and accidental oil and toxic spills have compounded these
changes.
11.6.1 Fisheries
Fishing grounds between 23°S and 43°S represent about 75 o/o of the total
fishery production between northern Brazil and southern Argentina (FAO
area 41). Today, the resources of these grounds are fully exploited (i.e.,
weakfish, royal weakfish, Argentine red shrimp, pink shrimp, all squids),
overexploited (i.e., hake, white mouth croaker, Brazilian sardine, several
C. Odebrecht and J.P. Castello
macro-zooplankton (i.e., Euphausia similis), the mesopelagic fish Maurolicus muelleri, and on squid.
The input of nutrients (mainly nitrate) through fertilization processes to
southern Brazilian shelf waters favors growth of large primary producers
(microplankton), like single centric diatoms or chains of small-celled species, chlorophyll-a nuclei, and high productivity rates (160 g C m- 2 year- 1 ;
Odebrecht and Garcia 1997). Shorter and less complex food chains are characterized by the dominance of planktophagous pelagic fish, like Engraulis
anchoita, and their predators (Merluccius hubbsi, Trichiurus lepturus,
Cynoscion guatucupa, Pagrus pagrus, Galeorhinus galeus, and the skates
Sympterigia acuta and S. bonapartei). Other zooplanktophagous species
include squids (Illex argentinus, Loligo sanpaulensis) and fishes (Anchoa
marinii, Trachurus lathami, juveniles of Cynoscion guatucupa, and Trichiurus lepturus). Over the outer shelf, pelagic zooplanktophagous species
are represented by Maurolicus muelleri, mictophyds, gonastomatids,
juvenile Merluccius hubbsi, Brama spp., Loligo sanpaulensis, Ornithoteuthis antillarum, and Illex argentinus, which also preys on small pelagic
and mesopelagic fishes. Pelagic-benthic interactions are especially important over the intermediate shelf (40-60 m) where high chlorophyll-a concentrations under the influence of SAW in winter coincide with high
demersal fish biomass (mainly sciaenids) in southern Brazilian waters
(Haimovici 1997b ).
11.6 Human Impacts
Demographic and industrial growth along the coast, fringing the warm
transition zone ecosystem in the SW Atlantic Ocean, threatens coastal
integrity. The pressure on fisheries stocks has deleterious effects on biodiversity and the sustainability of several activities. Coastal hazards, harmful algal blooms, and accidental oil and toxic spills have compounded these
changes.
11.6.1 Fisheries
Fishing grounds between 23°S and 43°S represent about 75 o/o of the total
fishery production between northern Brazil and southern Argentina (FAO
area 41). Today, the resources of these grounds are fully exploited (i.e.,
weakfish, royal weakfish, Argentine red shrimp, pink shrimp, all squids),
overexploited (i.e., hake, white mouth croaker, Brazilian sardine, several