The Patos Lagoon Estuary, Brazil
179
mactroides and the cirriped Balanus improvisus are the principal food
source for plankton-feeding juveniles of Atherinella brasiliensis and Odontesthes argentinensis in shallow waters while demersal (Brevoortia pectinata, Ramnogaster arcuata) and pelagic (Lycengraulis grossidens, Anchoa
marinii, Engraulis anchoita) fish are prominent plankton-feeders in
deeper waters. Several of the deposit-, suspension-, and plankton-feeding
secondary consumers are preyed upon by large individuals of Callinectes
sapidus, adults of larger fish (i.e., Micropogonias furnieri, Netuma barba,
N. planifrons) and by piscivorous birds, like the snowy egret (Egretta
thula), the green heron (Butorides striatus), the common bigua cormorant
(Phalacrocorax olivaceus), the common tern (Sterna hirundo), and the
black skimmer (Rynchops niger). Although large predators are scarce in the
estuary, Micropogonias furnieri, Trichiurus lepturus, and Mugil spp. are
also preyed upon by the bottlenose dolphin Tursiops truncatus (Vieira et
al. 1998; Fig. 12.3).
12.5 Estuary-Coast Interactions
The different estuarine habitats interface among each other and with adjacent coastal waters through processes of production, transport of matter
and organisms, and migrations. Short-term and seasonal patterns of the
exchange of water and organisms between the estuary and coastal nearshore areas tend to stabilize ecological processes and sustain the region's
considerable secondary production. The export of inorganic nutrients and
detritus at different stages of decomposition represents an important energy source for primary producers and a trophic link for coastal grazing and
detrital food chains (Abreu and Castello 1997). The enrichment of coastal
waters depends partly on the seeding of the estuary during saltwater intrusion with neritic diatoms (i.e., Skeletonema costatum) and their subsequent export as particulate organic carbon. In general, freshwater runoff
favors the occurrence of dense and large plankton patches in coastal
waters. Planktonic eggs and larvae (i.e., anchovy Engraulis anchoita) have
a better chance of survival because the freshwater lens stabilizes the water
column, thus inhibiting their dispersal and warranting access to food.
Furthermore, the deposition of organic matter during runoff supplies food
for filter- and suspension-feeding invertebrates and epibenthic and demersal fish and therefore sustains a diverse and abundant benthic community
(Capitoli 1998).
Extreme events of large-scale and long-term climatic and oceanographic forcing represent a major perturbation for the stability of ecological
179
mactroides and the cirriped Balanus improvisus are the principal food
source for plankton-feeding juveniles of Atherinella brasiliensis and Odontesthes argentinensis in shallow waters while demersal (Brevoortia pectinata, Ramnogaster arcuata) and pelagic (Lycengraulis grossidens, Anchoa
marinii, Engraulis anchoita) fish are prominent plankton-feeders in
deeper waters. Several of the deposit-, suspension-, and plankton-feeding
secondary consumers are preyed upon by large individuals of Callinectes
sapidus, adults of larger fish (i.e., Micropogonias furnieri, Netuma barba,
N. planifrons) and by piscivorous birds, like the snowy egret (Egretta
thula), the green heron (Butorides striatus), the common bigua cormorant
(Phalacrocorax olivaceus), the common tern (Sterna hirundo), and the
black skimmer (Rynchops niger). Although large predators are scarce in the
estuary, Micropogonias furnieri, Trichiurus lepturus, and Mugil spp. are
also preyed upon by the bottlenose dolphin Tursiops truncatus (Vieira et
al. 1998; Fig. 12.3).
12.5 Estuary-Coast Interactions
The different estuarine habitats interface among each other and with adjacent coastal waters through processes of production, transport of matter
and organisms, and migrations. Short-term and seasonal patterns of the
exchange of water and organisms between the estuary and coastal nearshore areas tend to stabilize ecological processes and sustain the region's
considerable secondary production. The export of inorganic nutrients and
detritus at different stages of decomposition represents an important energy source for primary producers and a trophic link for coastal grazing and
detrital food chains (Abreu and Castello 1997). The enrichment of coastal
waters depends partly on the seeding of the estuary during saltwater intrusion with neritic diatoms (i.e., Skeletonema costatum) and their subsequent export as particulate organic carbon. In general, freshwater runoff
favors the occurrence of dense and large plankton patches in coastal
waters. Planktonic eggs and larvae (i.e., anchovy Engraulis anchoita) have
a better chance of survival because the freshwater lens stabilizes the water
column, thus inhibiting their dispersal and warranting access to food.
Furthermore, the deposition of organic matter during runoff supplies food
for filter- and suspension-feeding invertebrates and epibenthic and demersal fish and therefore sustains a diverse and abundant benthic community
(Capitoli 1998).
Extreme events of large-scale and long-term climatic and oceanographic forcing represent a major perturbation for the stability of ecological