The ichthyofauna composition of the Baía da Ribeira was analyzed between December 1998 and November2001. The instruments used were an otter-trawl net, beach seines, cast net and visual census. It was registered two classes, composed by 16 orders, 59 families and 148 species. The high wealth of the region is due to the great diversity of environments and its location at the north limit of Argentine an Zoogeographic Province. The instruments diversification, the samples regions and the long sampling period were the responsables to the great numbers of collected species in comparison to some others studies at the same area.

Poecilia vivipara (Bloch & Schneider. 1801) is a species that lives in the Rodrigo de Freitas lagoon, a coastal lagoon in the city of Rio de Janeiro. The objective of this study was to increase the knowledge about reproductive aspects of P. vivipara population including: the female size when it begins reproduction, the number of offsprings per gestation, embrionary development stages and the number of pregnant females. The results show that P. vivipara reproduces throughout the whole year with its first maturation occurring at 29 mm. The proportion found of females to males was 3:1. Embryos showed four developmental stages until birth with sexual differentiation occurring after 15mm.

O monitoramento e a distribuição espacial de bactérias heterotróficas e coliformes fecais foram realizados em quatro áreas marginais da Laguna Rodrigo de Freitas, Rio de Janeiro. Amostras mensais foram coletadas no período de outubro de 1994 a setembro de 1998. A maior quantidade de bactérias heterotróficas foi de 6.5x10(7) UFC/100mL nas áreas 2 e 4 no mês de agosto de 1998, enquanto o menor valor encontrado foi de 10³ UFC/100mL na área 3 em fevereiro de 1995. Quanto aos coliformes fecais os maiores valores foram de 1.6x10(5) colif./100mL na área 3 em março de 1997 e os menores valores encontrados foram < 1 colif./100mL em fevereiro de 1995 e setembro de 1997 para todas as áreas, e fevereiro de 1998 para a área 3. Foi verificado um aumento ao longo do tempo dos percentuais de microrganismos nas áreas estudadas.

The distribution of heterothrophic bacteria and fecal coliforms was monitored at four sampling stations located near the shore of the Rodrigo de Freitas Lagoon, in the city of Rio de Janeiro, Brazil. Water samples were collected, monthly from October 1994 through September 1998. The highest heterothrophic count (6.5x10 7 CFU/100mL) was recorded at stations 2 and 4 during August 1998 and the lowest (10 ³ CFU/100 mL) at station 3 during February 1995. With respect to fecal coliforms, the highest and lowest counts were 1.6x10 5 coliforms/100mL at station 3 during March 1997 and <1 coliform/100mL at all the stations during February 1995 and September 1997 as well as station 3 during February 1998. The data indicated a percentage increase of the microorganisms surveyed over time at all the sampling stations studied.

From the results obtained in four years of monthly fish sampling and salinity and temperature verification of Lagoa Rodrigo de Freitas lagoon, an analysis of the monthly capture distribution of the nine most representative species, Brevoortia áurea (Spix, 1829), B. pectinata (Jenyns, 1842), Genidens genidens (Valenciennes, 1839), Geophagus brasiliensis (Quoy & Gaimard, 1824), Cerres aprion Cuvier, 1829, Jenynsia lineaía (Jenyns, 1842), Mugil liza (Valenciennes, 1836), Poecilia vivipara (Bloch & Schneider, 1801) and Xenomelani-ris brasiliensis (Quoy & Gaimard, 1824) was performed. The results show that Lagoa waters have an average salinity of 11.06% during the sampling period. Temperature showed its highest values from November to February and lowest values from June to August. G. brasiliensis, G. aprion, J. lineata,M. liza,P. viviparaeX. brasiliensis were constant during the 4 years. B. áurea showed highest frequency in year IV. B. pectinata was constant in years I and II and G. genidens showed only sparse captures.

The result of an agreement between Universidade Santa Ursula, Rio de Janeiro and the Museum of Natural History of Paris, was the oceanographic campaign MD-55 Brasil which took place between May 6th and June 2nd of 1987, aboard the R/V "Marion Dufresne" of the Terres Australes et Antartique Françaises (TAAF). Samples were collected between latitudes 23º36'40"S and 18º49'S. Ichthyofauna sampled was relatively low, and comprised of just one family of Chondrichthyes (three species) and 50 families of Osteichthyes (104 species). Zenion hololepsis (Goode & Bean, 1895) (Zeniodontidae) is recorded for the first time from the western South Atlantic, as well as is extended the geographic limits for Myrophis frio Jordan & Davis. 1892 (Ophichthidae) and Prionotus nudigula Ginshurg, 1950 (Triglidae). Even though relatively not very representative, the species collected from the seamount chain Vitoria/Trindade and Martin Vay suggest being identical to those which occur along the Brazilian continental platform.

This study gives information on the feeding habits of 1,015 specimens, belonging to the five most abundant fish species in the Jacarepagua Lagoon, captured between March 1990 and February 1991, using trawl net. A feeding index was introduced to compare the relative importance of various food items, according to species standard length. A clustering analysis was calculated by using numerical coefficient of food items and defined two main groups: The 1 st represented by Xenomelaniris brasiliensis (Quoy & Gaimard, 1824) and Jenynsia lineata (Jenyns, 1842) considered omnivorous, fed mainly on insects, and the second including Tilapia rendalli (Boulenger, 1896), Phalloptychus januarius (Hensel, 1868) and Poecilia vivipara (Bloch & Schneider, 1801), whose principal diet source was epibenthic cyanophytes, specially Microcystis sp. and Lyngbia sp.

Monthly sampling from march 1981 to april 1983 using beach seines, cast nets and gill nets indicated six species, Xenomelaniris brasiliensis, Brevoortia pectinata, Geophagus brasiliensis, Gerres aprion, Genidens genidens and Achirus lineatus, as the most abundant fishes in the Marependi Lagoon, Rio de Janeiro, BraziL The species presented a long reproductive period and the recruitment distributed throughout the year. Analysis of the mean catch per unit effort in relation to month, sampling areas, and environmental factors along with analysis of the length frequency distribution by depth strata indicated that the spatial distribution, related to depth and occurrence of submerged aquatic vegetation seem to be the main factors regulating the species distribution. Alteration of the environmental conditions in the lagoon due to the opening of the Marapendi channel in 1984 caused significative modification in the distribution and abundance patterns of the main species. The impact of these alterations in the Marapendi Lagoon fish community has yet to be determined.

From March 1985 to February 1987 montly cast net and beach seine sambles were collected at the Marapendi lagoon, Rio de Janeiro, Brazil, to describe its ichthyofauna and analyze associations between species and their distribution in areas with different salinity regimes. A stratified random sampling design was used and the lagoon diveided in four areas (1-4) according to salinity gradient. The "Bravais-Pearson" correlation index was utilized to analyze the similarity between species and between areas and also group them according to the UPGMA method. According to the results eight species groups were established. The majority of the species were wuryhaline, having a marine origin and were distributed in areas 1, 2 and 3 (high salinity areas). The formation of smaller groups with species of fresh water origin, which occurred in areas 2, 3 and 4 is also discussed.