214
G.M.E. Perillo et a!.
and summer (October-March) and leave as juveniles at the end of summer.
Juveniles and adults of Micropogonas furneri and Cynoscion striatus
coexist in the estuary during fall (Lopez Cazorla 1996) when they prey on
Peisos petrunkevitchi. The rest of the year they prey on other fishes, such as
Ramnogaster arcuata, but also on Micropogonas furneri and Cynoscion
striatus. Fishing activities inside the estuary are reduced and only about
600 tons of Micropogonias furnieri, Cynoscion striatus, and shrimps are
landed each year.
Large shallow areas of the estuary are visited by the cetacean "Franciscana" (Pontoporia blainvillei). A small colony of sea lions ( Otaria flavescens) at the outer part of the Principal Channel and at the tip of Trinidad
Island is occasionally preyed upon by killer whales. Several migratory bird
species of the Charadriiformes use Bahia Blanca Estuary as a resting and
feeding place and are abundant in channels, on muddy shores, and on the
islands (Belenguer et al.l992). The abundant Limosa haemastica is present
during the whole year, Calidris fuscicolis migrates during the winter, Calidris alba occurs during summer and fall, and Charadrius falklandicus
migrates during spring. Rare breeding colonies of the endemic crab or
Otrog seagull (Larus attruticus) are found on some islands where Chasmagnatus granulata is their exclusive diet.
14.5 Impact and Management
During the last 15 years, the city of Bahia Blanca has rapidly expanded to
a total of 350,000 inhabitants. The demographic growth has been fueled
by a large petrochemical park, fertilizer and thermoelectric plants, as
well as expanding port activities since much of Argentina's export moves
through Ingeniero White Port (and the subsidiaries Puerto Rosales, Base
Naval Puerto Belgrano, Puerto Galvan). As a consequence, the discharge
of industrial wastes (oil derivatives, pesticides, heavy metals, etc.) and
untreated domestic sewage (estimated at 10m 3 s- 1 ) has generated increasing problems of contamination. Furthermore, the Bahia Blanca region
represents the southern border of the wet "pampas" ( 680 mm year-') with
extensive agricultural production and cattle breeding, thus pesticide and
fertilizer addition to the estuary might be a potential hazard. However, concentrations of Cu (7.30jlg g- 1 ), Cd (0.44jlg g- 1 ), and Zn
(35.5 jlg g- 1 ) in sediments and total dissolved Cu and Zn levels in water
(Villa 1988) tend to be below contamination levels. Cadmium concentration (0.9-8.8jlg 1- 1 ) is comparable to that in estuarine mixing areas
(Sericano and Pucci 1982) and tributaries (Zubillaga and Pucci 1986)
G.M.E. Perillo et a!.
and summer (October-March) and leave as juveniles at the end of summer.
Juveniles and adults of Micropogonas furneri and Cynoscion striatus
coexist in the estuary during fall (Lopez Cazorla 1996) when they prey on
Peisos petrunkevitchi. The rest of the year they prey on other fishes, such as
Ramnogaster arcuata, but also on Micropogonas furneri and Cynoscion
striatus. Fishing activities inside the estuary are reduced and only about
600 tons of Micropogonias furnieri, Cynoscion striatus, and shrimps are
landed each year.
Large shallow areas of the estuary are visited by the cetacean "Franciscana" (Pontoporia blainvillei). A small colony of sea lions ( Otaria flavescens) at the outer part of the Principal Channel and at the tip of Trinidad
Island is occasionally preyed upon by killer whales. Several migratory bird
species of the Charadriiformes use Bahia Blanca Estuary as a resting and
feeding place and are abundant in channels, on muddy shores, and on the
islands (Belenguer et al.l992). The abundant Limosa haemastica is present
during the whole year, Calidris fuscicolis migrates during the winter, Calidris alba occurs during summer and fall, and Charadrius falklandicus
migrates during spring. Rare breeding colonies of the endemic crab or
Otrog seagull (Larus attruticus) are found on some islands where Chasmagnatus granulata is their exclusive diet.
14.5 Impact and Management
During the last 15 years, the city of Bahia Blanca has rapidly expanded to
a total of 350,000 inhabitants. The demographic growth has been fueled
by a large petrochemical park, fertilizer and thermoelectric plants, as
well as expanding port activities since much of Argentina's export moves
through Ingeniero White Port (and the subsidiaries Puerto Rosales, Base
Naval Puerto Belgrano, Puerto Galvan). As a consequence, the discharge
of industrial wastes (oil derivatives, pesticides, heavy metals, etc.) and
untreated domestic sewage (estimated at 10m 3 s- 1 ) has generated increasing problems of contamination. Furthermore, the Bahia Blanca region
represents the southern border of the wet "pampas" ( 680 mm year-') with
extensive agricultural production and cattle breeding, thus pesticide and
fertilizer addition to the estuary might be a potential hazard. However, concentrations of Cu (7.30jlg g- 1 ), Cd (0.44jlg g- 1 ), and Zn
(35.5 jlg g- 1 ) in sediments and total dissolved Cu and Zn levels in water
(Villa 1988) tend to be below contamination levels. Cadmium concentration (0.9-8.8jlg 1- 1 ) is comparable to that in estuarine mixing areas
(Sericano and Pucci 1982) and tributaries (Zubillaga and Pucci 1986)