This work had as objective to study the distribution and abundance of the

As variações espaciais e sazonais da distribuição e abundância do ictioplâncton foram estudados na costa norte da Bahia. Amostragens foram feitas em 12 estações em maio/1993, setembro/1993, dezembro/1993 e março/1994. O ictioplâncton foi coletado através de arrastos oblíquos utilizando-se rede bongo com malha de 500 µm. Foram dentificadas 12 Ordens, 33 famílias e 20 espécies de larvas de peixes. A abundância relativa das famílias características foram as seguintes: Gobiidae (25%), Gerreidae (11%), Engraulidae (11%), Clupeidae (10%), Carangidae (7%), Myctophidae (5%), Haemulidae (5%), e Scombridae (3%). A densidade de ovos de peixes apresentou coeficientes de correlação de Pearson positivos e significativos (r > 0,7), com a temperatura, turbidez, ortofosfato, biomassa fitoplanctônica e biomassa de microplâncton. A densidade de larvas de peixes apresentou coeficientes de correlação positivo e significativos (r > 0,7), com a saturação de oxigênio e salinidade. A utilização do litoral norte da Bahia, como sítio de desova e criação de larvas de peixes, foi verificada em todas as épocas do ano, com maior densidade de ovos no período chuvoso (água Costeira) e maior densidade de larvas durante o período seco (água Oceânica). Palavras chave: Ictioplâncton, Distribuição, Costa Norte da Bahia

This study investigated the large-scale spatial and temporal variability of larval fish assemblages in the west tropical Atlantic Ocean. The sampling was performed during four expeditions. Identification resulted in 100 taxa (64 families, 19 orders and 17 suborders). During the four periods, 80% of the total larvae taken represented eight characteristics families (Scombridae, Carangidae, Paralepididae, Bothidae, gonostomatidae, Scaridae, gobiidae and Myctophidae). Fish larvae showed a rather heterogeneous distribution with density at each station ranging from 0.5 to 2000 larvae per 100m3. A general trend was observed, lower densities at oceanic area and higher densities in the seamounts and islands. A gradient in temperature, salinity, phytoplankton biomass, zooplankton biomass and station depth was strongly correlated with changes in ichthyoplankton structure. Myctophidae, and Paralepididae presented increased abundance at high salinities and temperatures. Bothidae and gobiidae were more abundant at higher phytoplankton biomass and zooplankton biomass. Scaridae, Scombridae and gonostomatidae had higher abundances at deep offshore stations. Different events might be responsible for the formation, maintenance and breakdown of fish larvae assemblage in the tropical oceanic area of Brazil. The results suggested that the oceanographic variables (temperature, salinity, phytoplankton biomass, zooplankton biomass and station depth) played an important role on the distribution patterns of ichthyoplankton.

O objetivo deste estudo foi delinear a distribuição espacial e sazonal e analisar a influência de fatores oceanográficos (temperatura, salinidade, biomassa primária e biomassa secundária) sobre a densidade de larvas de Katsuwonus pelamis. Os cruzeiros foram realizados à bordo do Navio Oceanográfico Antares da Marinha do Brasil, na Zona Econômica Exclusiva (ZEE) do Nordeste do Brasil, em 1995 (REVIZEE Nordeste I), 1997 (REVIZEE Nordeste II) e 1998 (REVIZEE Nordeste III). Realizou-se a coleta do macrozooplâncton através de arrastos oblíquos com rede bongo, com malha 500 µm. O bonito-barriga-listrada destacou-se como a espécie mais abundante da família Scombridae, atingindo cerca de 50% da abundância relativa total. A distribuição espacial de K. pelamis, em larga escala, ocorreu de forma independente em relação aos parâmetros oceanográficos estudados. Não foi registrada influência da sazonalidade uma vez que não foram detectadas diferenças significativas entre as três épocas investigadas. Palavras chave: Ictioplâncton, Katsuwonus pelamis,Zona Econômica Exclusiva

Todos os Santos Bay, having an area of approximately 927 km2, is the largest Bay on the Brazilian coast. Four sampling surveys, in two rainy and two dry periods, were made at five locations of Todos os Santos Bay, Bahia, Brazil, aiming to identify environmental and ecotoxicological correlates of ichthyoplankton assemblage structure. The study area showed a community characterised by the domination of Engraulididae, Gobiidae (Gobionellus spp.), Gerreidae (Diapterus spp. and Eucinostomus spp.) and Carangidae (Oligoplites spp. and Caranx spp.) larvae. There wasn't a significant difference in composition of fish larvae between the sampling periods, but there was a significant temporal variability in the most important environmental variables. The results showed statistically significant differences between northern stations and the control site, only for ammonium–nitrogen and total fish larvae density. The environmental variables (temperature, ammonium-nitrogen, oil and grease and chlorophyll a) explained 94.7% of the variation of the larval fish assemblage.

Relationship between spatial distribution of chaetognaths and hydrographic conditions around seamounts and islands off Northeastern Brazil were analyzed from 133 oceanographic stations during the months of January -April of 1997 and April -July of 1998. Oblique zooplankton tows, using 50 cm diameter Bongo nets with 500µm mesh with a flowmeter to determine the filtered volume, were carried out to a maximum of 200m depth. The Superficial Equatorial Water, which had a salinity > 36 PSU and temperature > 20ºC, occupied the top 80 to 200m depth. Below this water mass was the South Atlantic Central Water with salinity ranging from 34.5 to 36 PSU and temperature from 6 to 20°C. The community of chaetognaths showed six species: Pterosagitta draco, Flaccisagitta enflata, Flaccisagitta hexaptera, Pseudosagitta lyra, Serratosagitta serratodentata, and Sagitta helenae. Of these species, F. enflata was the most abundant (32.05% in 1997 and 42.18% in 1998) and the most frequent (87.88% in 1997 and 95% in 1998) during both periods. A mesopelagic specie was identified (P. lyra). This specie was more abundant in 1997 (3.42%), when the upwelling was more intense. P. lyra occurred in 22% of the samples during 1997. The abundance of F. enflata, an epiplanktonic species, increased, associated with greater water-column stability.

Data collected on two large-scale surveys around the seamounts and islands off north-eastern Brazil during 1997 and 1998 provided information on the distribution of Chlorophyll a and inorganic nutrients. During both surveys, the concentrations of Chlorophyll a and nutrients were highly patchy. The highest measurement of Chlorophyll a was 3.91 µg L–1 during 1997. A wide range of nutrient concentrations were found, from undetectable values to a maximum of 17.52 µm L–1 (Si), 1.37 µm L–1 (PO4), 10.02 µm L–1 (NO3) and 0.72 µm L–1 (NO2). In 1998, concentrations of Chlorophyll a and nutrients (nitrite and nitrate) were far more uniform, with Chlorophyll a concentrations lower and phosphate concentrations generally higher than in 1997. Topography–flow interaction on thermohaline structures was observed around Saint Peter and Saint Paul Archipelago and in the Fernando de Noronha Chain, creating a patchy pattern around the island and seamounts. Nutrients exhibited an inverse linear relationship with temperature and salinity and an exponential decay relationship with Chlorophyll a.

O objetivo deste estudo foi realizar uma avaliação da distribuição espacial e temporal da biomassa planctônica, e suas relações com as condições oceanográficas e pluviosidade na Zona Econômica Exclusiva do Nordeste Brasileiro. As amostras foram coletadas em oito áreas, durante um período seco (Expedição Nordeste II, 1997) e outro chuvoso (Expedição Nordeste III, 1998). Os maiores valores de biomassa primária foram encontrados no Talude Norte e no Talude Sul, tanto no período seco como no chuvoso. Nos dois períodos de estudo os maiores valores de biomassa secundária foram encontrados na Cadeia Norte Brasileira e na área Oceânica Leste, provavelmente em função da contribuição de ressurgências topográficas nas áreas oceânicas. A variação espacial e temporal nos valores de biomassa fitoplanctônica e zooplanctônica provavelmente devem ser atribuídos a fenômenos meteorológicos que condicionaram a variabilidade térmica e salina. Palavras chave: Biomassa primária, biomassa secundária, hidrografia, Zona Econômica Exclusiva.