192
H. Mianzan et a!.
rugosa, S. lessoni, Littorina ziczac). The lower littoral is occupied by mytilids (Brachidontes darwinianus, B. rodriguezi, Mytella charruana, Mytilus
edulis platensis, Perna perna), crustaceans (mainly Balanus improvisus,
Cyrtograpsus angulatus ), and algae ( Ulva lactuca, Corallina officinal is,
Polysiphonia sp., Chondria sp., Enteromorpha sp.; Scarabino et al. 1975;
Maytia and Scarabino 1979).
Coastal marshes of the Uruguayan coast are colonized by halophytic
vegetation (Spartina montevidensis, S. longispina, ]uncus acutus, Salicornia ambigua; Boschi 1988), while Spartina alterniflora, S. densiflora, Scirpus maritimus, Salicornia ambigua, and S. virginica are abundant along
tidal creeks and mudflats in Samboromb6n Bay (Ringuelet 1938), which
are dominated by dense populations of crabs (cangrejales). Chasmagnatus
granulata inhabits burrows in sediments of supra- and mesolitoral zones
and feeds on Spartina detritus or preys on small invertebrates (Botto and
Irigoyen 1979). Uca uruguayensis occurs in upper consolidated substrates,
while submerged lower levels are typical of Cyrtograpsus angulatus
(Boschi 1979). Faunal assemblages of tidal and subtidal flats near Punta
Rasa are characterized by a mixohaline, muddy-fine sand community with
polychaetes (Heteromastus similis and Laeonereis acuta) and low Shannon
index values ( <1.60; leno and Bastida 1998).
13.3.2.3 Nekton
Mixohaline waters are dominated by euryhaline species of marine heritage
(Boschi 1988). The Sciaenidae Micropogonias furnieri, Macrodon ancylodon, and Paralonchurus brasiliensis are common in brackish and coastal
waters and some (Micropogonias furnieri, Pogonias cromis) have a wide
distributional range. The common soles Symphurus jennynsi and Paralichthys orbignyanus (Paralichthydae) are abundant and the commercially
valuable P. orbignyanus and P. cromis may exceed 20 kg and 100 em in total
length. Conger orbignyanus (Anguilliformes) also occurs in continental
shelf areas. Other conspicuous species are Brazilian menhaden Brevoortia
aurea, Ramnogaster arcuata (Clupeidae), Anchoa marinii (Engraulidae),
Austroatherina incisa (Atherinidae), and Netuma barbus (Ariidae). Adults
of the anadromous anchovy Lycengraulis grossidens ( =olidus; Engraulidae) are common in the estuary (November to April) and breed during
early spring in the Parana and Uruguay rivers and their tributaries (Fuster
de Plaza and Boschi 1961). Among the elasmobranchs Sympterygia bonapartei, S. acuta, Raja castelnaui, and R. agassizi are the most abundant
species while the sting rays Myliobatis goodei and Discopyge tschudii are
common, the latter mainly in spring and summer (Cousseau 1985).
H. Mianzan et a!.
rugosa, S. lessoni, Littorina ziczac). The lower littoral is occupied by mytilids (Brachidontes darwinianus, B. rodriguezi, Mytella charruana, Mytilus
edulis platensis, Perna perna), crustaceans (mainly Balanus improvisus,
Cyrtograpsus angulatus ), and algae ( Ulva lactuca, Corallina officinal is,
Polysiphonia sp., Chondria sp., Enteromorpha sp.; Scarabino et al. 1975;
Maytia and Scarabino 1979).
Coastal marshes of the Uruguayan coast are colonized by halophytic
vegetation (Spartina montevidensis, S. longispina, ]uncus acutus, Salicornia ambigua; Boschi 1988), while Spartina alterniflora, S. densiflora, Scirpus maritimus, Salicornia ambigua, and S. virginica are abundant along
tidal creeks and mudflats in Samboromb6n Bay (Ringuelet 1938), which
are dominated by dense populations of crabs (cangrejales). Chasmagnatus
granulata inhabits burrows in sediments of supra- and mesolitoral zones
and feeds on Spartina detritus or preys on small invertebrates (Botto and
Irigoyen 1979). Uca uruguayensis occurs in upper consolidated substrates,
while submerged lower levels are typical of Cyrtograpsus angulatus
(Boschi 1979). Faunal assemblages of tidal and subtidal flats near Punta
Rasa are characterized by a mixohaline, muddy-fine sand community with
polychaetes (Heteromastus similis and Laeonereis acuta) and low Shannon
index values ( <1.60; leno and Bastida 1998).
13.3.2.3 Nekton
Mixohaline waters are dominated by euryhaline species of marine heritage
(Boschi 1988). The Sciaenidae Micropogonias furnieri, Macrodon ancylodon, and Paralonchurus brasiliensis are common in brackish and coastal
waters and some (Micropogonias furnieri, Pogonias cromis) have a wide
distributional range. The common soles Symphurus jennynsi and Paralichthys orbignyanus (Paralichthydae) are abundant and the commercially
valuable P. orbignyanus and P. cromis may exceed 20 kg and 100 em in total
length. Conger orbignyanus (Anguilliformes) also occurs in continental
shelf areas. Other conspicuous species are Brazilian menhaden Brevoortia
aurea, Ramnogaster arcuata (Clupeidae), Anchoa marinii (Engraulidae),
Austroatherina incisa (Atherinidae), and Netuma barbus (Ariidae). Adults
of the anadromous anchovy Lycengraulis grossidens ( =olidus; Engraulidae) are common in the estuary (November to April) and breed during
early spring in the Parana and Uruguay rivers and their tributaries (Fuster
de Plaza and Boschi 1961). Among the elasmobranchs Sympterygia bonapartei, S. acuta, Raja castelnaui, and R. agassizi are the most abundant
species while the sting rays Myliobatis goodei and Discopyge tschudii are
common, the latter mainly in spring and summer (Cousseau 1985).