Dynamic of decapod crustacean larvae on the entrance of Guanabara bay

Abstract

In the present study, we observed seasonal variations in the density of decapod larvae as well as changes in density related to diurnal and tidal cycles. Among the decapod larvae collected, portunids and grapsids were the most abundant, especially during nocturnal ebb tides and near the surface. The same results were obtained in late winter (September) and late summer (March). These results demonstrated a flow of decapod larvae from Guanabara Bay to adjacent coastal waters. Luciferid (Lucifer faxoni) was the only group with high densities during flood tides and we suggest this is an evidence of L. faxoni larvae entering Guanabara Bay in late winter. Probably these changes in distribution of Lucifer faxoni among winter and summer were related to reproductive cycle in the bay. For the portunids, grapsids and ocypodids, a similar dispersion strategy was observed towards adjacent coastal waters in the surface during nocturnal ebb tides.<br>Larvas de crustáceos decápodes são organismos planctônicos comuns tanto em regiões costeiras rasas como em estuários. Nesse trabalho, foi acompanhada a variação da densidade das larvas de decápodes num ponto estratégico entre a porção interior da baía de Guanabara e a região costeira adjacente. A coleta de grandes quantidades de zoés de braquiúros, principalmente das famílias Portunidae e Grapsidae, na superfície durante as marés de vazante noturnas sugere uma tendência de exportação para a região costeira adjacente. A repetição desse padrão no inverno e no verão demonstrou que as respostas dos organismos às variações de luz e maré não foram alteradas de modo significativo entre as duas estações do ano, exceto para os luciferídeos. O fluxo observado para a única espécie de luciferídeo capturada (Lucifer faxoni) foi significativamente diferente entre os dois períodos do ano analisados. É provável que essas diferenças na distribuição de Lucifer faxoni seja relacionada ao ciclo reprodutivo da espécie. Foi observado um padrão de dispersão similar para as larvas zoé dos portunídeos, grapsídeos e ocypodídeos; transporte para a região costeira adjacente pela superfície durante as marés de vazante noturnas

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

“…The higher larval densities recorded during night sampling at Guanabara Bay and in other studies (Bridger, 1956;Phonlor, 1973;Castro and Bonecker, 1996;Hettler et al, 1997) could be related to net avoidance by larger larvae during the day (Matsuura, 1977) and to vertical migration so that the larvae assembled near the bottom during the day and dispersed through the water column at night (Bridger, 1956;Bonecker et al, 2002). Other meroplanktonic organisms such as decapod larvae have a similar diurnal pattern in Guanabara Bay (Fernandes et al, 2002). Although tide cycle did not influence significantly larval densities in the present study, higher values during ebb and early flood tide at night sampling, could be an indication that fish larvae be exported from the bay at this period.…”

Spatial and temporal distribution of decapod larvae in the subtropical waters of the Arvoredo archipelago, SC, Brazil

“…However, estuarine systems show a tendency to higher decapod concentrations. In Guanabara Bay, decapod densities ranged from 1.3 to 612 ind.m -3 in summer and from 0.4 to 788 ind.m -3 in winter, with brachyuran zoea frequently representing more than 90% of total (FERNANDES et al, 2002). In the Itamaracá estuarine system, mean decapod concentration was of 784.7 ind.m -3 , with brachyurans zoeae representing approximately 90.86% (SCHWAMBORN, 1997).…”

“…Decapod larval ecology studies are scarce in Brazil and a proportion of these studies remain as unpublished thesis and monographs of limited availability. Published research includes studies of blue crabs and shrimps conducted by CALAZANS (2002) in the Patos Lagoon estuary, studies of shrimps (FEHLAUER & FREIRE, 2002;CALAZANS, 1994CALAZANS, , 1999 on the southern coast and studies of decapods in the Guanabara Bay (FERNANDES et al, 2002), on the eastern coast and in the Itamaracá estuarine system on the northeastern coast (SCHWAMBORN, 1997;SCHWAMBORN et al, 2001). Other data could be available in general zooplankton studies or in an thesis on mangrove crabs (A. S. Freire, unpublished data) or in the surf zone (J. G. Bersano, unpublished data).…”

Zooplankton and ichthyoplankton distribution on the southern Brazilian shelf: an overview

“…However, Ekman transport may carry eggs and larvae offshore, and depending on the extent of such advective transport, survival and growth rates of the fish larvae could be lowered (Spach, 1990). The only evidence of offshore transport impacting other zooplankton groups in the region are not related to wind-driven circulation, but rather to tidal transport of estuarine decapod larvae towards the shelf (Veloso and Valentin, 1993;Fernandes et al, 2002). Bakun and Parrish (1990) and Bakun (1996) have discussed the remarkable similarities between the Brazilian sardine and the California sardine stocks in terms of reproductive strategies.…”