Sérgio Luiz Costa Bonecker

Dynamic of decapod crustacean larvae on the entrance of Guanabara bay

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.

Seasonal variability of planktonic copepods (Copepoda: Crustacea) in a tropical estuarine region in Brazil

The Caravelas River estuary and adjacent coastal region were studied during the rainy and dry seasons of 2003-2004 to assess the copepod community structure. Abiotic and biotic parameters were measured, and the total density, frequency and percentage of copepod taxa were determined for each sampling period. Copepod densities showed significant differences between sampling periods, with higher densities in the rainy seasons (Mean: 90,941.80 ind.m-3; S.D.: 26,364.79). The sampling stations located to the north and south, in the coastal region adjacent to the Caravelas River estuary presented the lowest copepod density values. The copepod assemblage was composed mainly of estuarine and estuarine/coastal copepods. The seasonal variations in temperature and salinity influenced the abundance of species during the rainy and dry seasons, with the following dominant species alternating: Paracalanus quasimodo Bowman, 1971 in the rainy season of 2003, Parvocalanus crassirostris Dahl, 1894 in the dry season of 2003 and Acartia lilljeborgii Giesbrecht, 1892 in the rainy and dry seasons of 2004. Non-parametric multidimensional scaling indicated differences in copepod assemblages between sampling periods, but not between sampling stations.

Inter-annual variability of planktonic copepods in a tropical bay in southeastern Brazil

The aim of this work was to study the structure of the copepod community in relation to hydrographic conditions in Espirito Santo Bay, from 1993 to 1997. Zooplankton samples were obtained in the horizontal tows four times a year, using a 200 µm net. Temperature, salinity and dissolved oxygen were determined in the water samples. The overall mean density of the copepods was 9,085 ind.m-3 with the peaks exceeding 15,000 ind.m-3 in the summer and autumn during the first three years (1993 - 1995). The PCA analysis was used to relate the environmental conditions with the distribution of the copepods. The increases in the abundant species, namely Acartia lilljeborgi, Oithona hebes, Oithona oculata, Paracalanus quasimodo, Parvocalanus crassirostris and Euterpina acutifrons, were related to the decreases in the diversity. The spatial and temporal variations of the temperature and salinity influenced the abundance of the species during the five years of the sampling and the dominant species alternated in abundance.

Horizontal and vertical distribution of mesozooplankton species richness and composition down to 2,300 m in the southwest Atlantic Ocean

We describe the species richness, distribution and composition of mesozooplankton over the continental shelf and slope, and in the water masses in the Campos Basin, southwest Atlantic Ocean. We analyzed the mesozooplankton from two oceanographic cruises (rainy and dry seasons, 2009) with samples taken in five different water masses from the surface to 2,300 m depth. In the Subsurface Water (SS), in both sampling periods, more species were recorded over the slope (rainy: 100; dry: 128) than the continental shelf (rainy: 97; dry: 104). Over the slope, species richness decreased with increasing depth: the highest values were observed in the South Atlantic Central Water (SACW), and the lowest values in the North Atlantic Deep Water (NADW), in both sampling periods. We recorded 262 species in 10 groups (Hydrozoa, Siphonophora, Ctenophora, Branchiopoda, Copepoda, Euphausiacea, Decapoda, Chaetognatha, Appendicularia e Thaliacea), with 13 new occurrences for the southwest Atlantic. Copepoda was the group with the highest species richness, containing 138 species. In both periods, the samples from SS, SACW and Antarctic Intermediate Water (AAIW)/Upper Circumpolar Deep Water (UCDW) were clustered in different faunistic zones, based on species composition. This study confirmed that zooplankton richness in the southwest Atlantic Ocean is underestimated, and suggests that additional efforts must be directed toward a better understanding of this fairly unknown region.

Seasonal and spatial variability of appendicularian density and taxonomic composition in the Caravelas Estuary (Northeastern Brazil) and adjacent coastal area

This study aimed to identify and assess the seasonal and spatial variations of the appendicularians in the Caravelas River estuary and the adjacent coastal area. Samples were taken during 12 campaigns over five years (2001 and 2003-2006). Ten species were identified; the most abundant were Oikopleura dioica, Oikopleura rufescens, and Oikopleura longicauda. These species represented more than 95% of the total numbers of appendicularians. The remaining species were less frequent and occurred in low densities. The mean density of appendicularians found at the coastal stations (804 ind.m-3.) was higher than in the estuary (66 ind.m-3). However, the differences observed between the estuary and coastal stations were not significant (p=0.54). The samples taken during the dry season showed a higher mean density (587 ind.m-3) than in the rainy season (376 ind.m-3), and the differences between the seasons were statistically significant (p=0.004).

The copepod assemblage (Copepoda: Crustacea) on the inner continental shelf adjacent to Camamu Bay, northeast Brazil

The copepod assemblage on the inner continental shelf adjacent to the coastal system of Camamu Bay (state of Bahia, Brazil) is described in relation to hydrographic conditions, during the wet and dry seasons of 2004. The zooplankton samples were obtained in vertical tows using a net with 200 µm mesh size. Temperature and salinity were measured, and the total density, frequency and percentage occurrence of the copepod taxa were determined for each sampling period. The highest densities were observed at the entrance of Camamu Bay (up to 7.473 ind.m-3), and the lowest on the adjacent inner continental shelf south of Camamu Bay (less than 500 ind.m-3). A total of 57 copepod taxa were identified. Paracalanus quasimodo Bowman, 1971, Subeucalanus pileatus (Giesbrecht, 1888), Clausocalanus furcatus (Brady, 1883), Corycaeus giesbrechti F. Dahl, 1894, Temora turbinata (Dana, 1849), Oithona similis Claus, 1866, Temora stylifera (Dana, 1849) and Nannocalanus minor (Claus, 1863) dominated numerically. The densities measured in both sampling seasons were significantly different: the means were 1.849 ± 1.922 ind.m-3 and 3.657 ± 3.170 ind.m-3 for the wet season and dry season, respectively. Depth and temporal variation in temperature and salinity influenced species abundance during the wet and dry seasons, with the dominant species alternating. Species richness and diversity increased on the inner shelf adjacent to the coastal system of Camamu Bay at the 30- and 50-m isobaths, suggesting that most species were oceanic in origin. The diversity was similar to other coastal systems of northeast Brazil.

New records of Monstrilloida Sars, 1901 (Crustacea, Copepoda) on the Brazilian northeastern coast

During a series of zooplankton surveys carried out from 2001 through 2005 off the coast of the state of Bahia, Brazil, 98 individuals of monstrilloid copepods were collected. These belong to five species (Monstrilla grandis, Cymbasoma cf. longispinosum, Cymbasoma cf. rigidum, Cymbasoma gracilis, and Cymbasoma quadridens). The first three are recorded for the first time in the Bahia coastal region. The geographical range of C. quadridens is expanded to the Brazilian northeastern coast. The results presented herein increase to nine the number of nominal species of Monstrilloida known from off Bahia; the environmental diversity of Caravelas Channel with highly productive areas and coral reef zones harbor an abundant and diverse monstrilloid fauna that should be surveyed in more detail.

Analysis of the Appendicularia class (subphylum Urochordata) as a possible tool for biomonitoring four estuaries of the tropical region

This study aims to characterize the differences between physical and chemical parameters of water quality indicators and eutrophication in four estuaries of the state of Rio de Janeiro and relate them to full density of the species that belong to the Appendicularia class with the purpose of seeking bioindicators for estuarine areas. The estuaries studied were from the rivers Macaé, São João, Bracuí, and Perequê-Açu. The physicochemical parameters monitored for evaluation of the water bodies and used for the correlation with the appendicularians were pH, temperature, nitrite, nitrate, N-ammonia, total nitrogen, phosphate, total phosphorus, dissolved oxygen (DO), suspended particulate matter (SPM), chlorophyll a, heterotrophic bacteria, and fecal coliform. The estuaries Bracuí and São João showed enhanced qualities of water and lower degrees of eutrophication than Macae and Perequê-Açu estuaries. The species of the Appendicularia class found in this study were Oikopleura longicauda (Vogt, 1854), Oikopleura dioica Fol, 1872, Oikopleura fusiformis Fol, 1872, and Fritillaria haplostoma Fol, 1872. The density of appendicularians and O. longicauda was inversely related to the nutrient values and SPM; nonetheless, no species of appendicularians could be used as a bioindicator of any estuary in the current study. Studies on the quality of estuary waters and the search for other bioindicators belonging to other zooplankton groups are recommended to confirm the obtained results and to expand the knowledge of these coastal environments.

Larvae of the family Stenopodidae (Crustacea: Stenopodidea) from South Atlantic Ocean

Stenopodidae comprises about 2 8 species in tropical and subtropical waters around the world, but only two of them in the South Atlantic Ocean (SAO)—Stenopus scutellatus and S. hispidus. Larvae of S. scutellatus were never registered in SAO and those of S. hispidus remain poorly researched. The present study fully describes first to seventh zoea of S. hispidus collected in the plankton of SAO, adjacent to Brazil. In addition, eight larvae of S. scutellatus and two larvae of non-identified Stenopodidea from the same area were also described.

Variações na estrutura da comunidade zooplanctônica próxima a usina I da Central Nuclear Almirante Álvaro Alberto (C.N.A.A.A.) - (Angra Dos Reis-R.J.-Brasil) - Ciclo 1980/81 E 1991/93

During the years of 1980/80 was performed a ecological study in Ribeira Bay (Angra dos Reis-R.J.-Brazil) in order to provide informations about of the planktonic community in pre-operational conditions, in the region of the Admiral Alvaro Aberto Nuclear Power Plant (C.N.A.A.A.). After 10 years of activities of the Nuclear Power Plant the zooplankton material was obtained in vertical hauls with a net of 150 μm at two fixed points (Piraquara de Fora Cove and Itaorna Beach) in order to study the zooplankton associations related to environmental variables and comparing with the anterior study. The zooplankton evolution showed a sazonal variation with the dominance of the holoplanktonic organisms. The Copepoda showed its the greatest growth during the autumn and the winter. During the summer and the spring its relative abundance suffered a progressive diminution when the Cladocera passed to be the more representative organisms without a competition between its. The sazonal variation presented by the organisms was related with the raining period that fall in the region.