Caracterização do ictioplâncton na entrada da Baía de Guanabara (RJ)

Abstract

The present study was carried out in the entrance of the Guanabara Bay (RJ) Twenty-four samplings were realized, with six stations in the entrance of the bay. The water temperature and salinity, in the surface and near the bottom, were measured. The water transparency was measured with Secchi disc. The ichthyoplankton was collected by oblique hauls with bongo net and by horizontal hauls with nêuston net. In both nets, 500 µm mesh were utilized. The nets were hauled at about ten minutes. Calibrated flowmeters were adapted in the both nets. Specific diversity of fish larvae was calculated.,Interrelations of biotic and abiotic data were statistically analysed. The number of fish eggs and larvae collected by nêuston net was higher, however the bongo net collected higher taxons variety. Total of 3,061,570 eggs.100m -3 and 40,492 larvae.100m -3 were collected. In the fish eggs collected, 40% were the Engraulidae family. Two species were identified, Anchoa lyolepis was more frequent during the two years and more abundant in the winter periods, while Cetengraulis edentulus was not frequent all the year and presented high abundances in the summer periods. In relation to fish larvae, a total of 35 families and 42 species were identified.

Seasonal variation in fish larvae at the entrance of Guanabara Bay, Brazil

“…The species collected in the present study were all coastal fishes common in estuaries and other coastal regions of Brazil (Phonlor, 1973(Phonlor, , 1975Oliveira and Krau, 1976;Weiss, 1981;Sinque et al, 1982;Bonecker et al, 1991;Katsuragawa et al, 1993;Castro and Bonecker, 1996;Ibagy and Muelbert, 1997). In addition to the species identified in this study, members of the families Synodontidae, Exocoetidae, Mugilidae, Atherinidae, Fistularidae, Dactyloscopidae, Sphyraenidae, and Bothidae also occurred in Guanabara Bay (Bonecker, 1997). The families Engraulidae and Clupeidae were the most abundant taxa in Guanabara Bay and were widespread on the southeastern coast of Brazil (Mazzetti and Hubold, 1982;Matsuura, 1983;Houde and Lovdal, 1984;Spach, 1990;Katsuragawa et al, 1993;Bonecker, 1997).…”

“…In addition to the species identified in this study, members of the families Synodontidae, Exocoetidae, Mugilidae, Atherinidae, Fistularidae, Dactyloscopidae, Sphyraenidae, and Bothidae also occurred in Guanabara Bay (Bonecker, 1997). The families Engraulidae and Clupeidae were the most abundant taxa in Guanabara Bay and were widespread on the southeastern coast of Brazil (Mazzetti and Hubold, 1982;Matsuura, 1983;Houde and Lovdal, 1984;Spach, 1990;Katsuragawa et al, 1993;Bonecker, 1997). High egg and larval densities of these families in Guanabara Bay, mainly during summer (Kraus and Bonecker, 1994;Bonecker, 1997) could be related to the fact that some species have short life cycle and high reproductive capacity (Katsuragawa et al, 1993).…”

“…The families Engraulidae and Clupeidae were the most abundant taxa in Guanabara Bay and were widespread on the southeastern coast of Brazil (Mazzetti and Hubold, 1982;Matsuura, 1983;Houde and Lovdal, 1984;Spach, 1990;Katsuragawa et al, 1993;Bonecker, 1997). High egg and larval densities of these families in Guanabara Bay, mainly during summer (Kraus and Bonecker, 1994;Bonecker, 1997) could be related to the fact that some species have short life cycle and high reproductive capacity (Katsuragawa et al, 1993). Two engraulids were identified in the bay: the anchovy A. lyolepis that used coastal waters and Guanabara Bay as nurseries, and C. edentulus that completed its life cycle entirely within the bay (Mazzetti and Hubold, 1982).…”

“…Temperature increase is a controller of spawning and recruitment periods, because most species spawn during the summer months (Phonlor, 1984). Along the Brazilian coast, densities of fish larvae increase during summer (December to March) (Phonlor, 1973(Phonlor, , 1984Weiss, 1981;Sinque et al, 1982;Kraus, 1995;Katsuragawa et al, 1993;Castro and Bonecker, 1996;Bonecker, 1997). Because Guanabara Bay is situated in a tropical region, spawning occurs from January to April (Vazzoler, 1992), which is the hottest period of the year .…”

“…These exchanges have focused scientific attention towards understanding the transport and recruitment mechanisms of fish larvae within estuarine environments (Norcross and Shaw, 1984;Shaw et al, 1988;Wang, 1988;Whitfield, 1989;Ré, 1990;Neira and Potter, 1992;Schwamborn and Bonecker, 1996). Although Guanabara Bay has great socioeconomic and ecological importance, few studies about ichthyoplankton community have been developed (Kraus and Bonecker, 1994;Kraus, 1995;Bonecker, 1997), and the same has been observed for adult community (Mazzetti and Hubold, 1982;Barroso, 1989;Tubino, 1996). The present study analyzed seasonal variation in abundance of fish larvae, and evaluated the influence of tidal and day/night cycles on larval density.…”