Abstract The spatio-temporal distribution of juveniles of the pink shrimps Farfantepenaeus brasiliensis (Latreille, 1817) and Farfantepenaeus paulensis (Pérez-Farfante, 1967) in the Ubatuba region (SP) was investigated. Sampling was performed in the bays of Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV). A total of 2,018 F. brasiliensis and F. paulensis were collected. The largest catch of juveniles of both species occurred in UBA (N = 867), followed by UBM (N = 729) and MV (N= 422). The bottom sediment in MV had the highest silt and clay content, which explains the negative correlation of the substrate with the abundance of both species. Temperature was positively correlated with the abundance of both species. Juveniles were highly abundant in shallower areas in the summer of 1998. The high rainfall in this El Niño period may have lowered the salinity in estuarine waters and led the shrimps to move to coastal areas in search of higher salinities such as in bays. With this unusually early reduction in salinity, individuals migrated to the bay before the closed season began and thus became more exposed to fishing. We confirmed that monitoring environmental variations, especially in El Niño years, is essential for understanding the distribution patterns of juveniles of both species.

ResumoFoi investigada a dinâmica populacional de Acetes americanus, enfocando a razão sexual, crescimento dos indivíduos, longevidade, recrutamento e a relação da abundância com dos fatores ambientais na região de Macaé, a qual é fortemente influenciada pela ressurgência costeira. Foram realizadas coletas de julho de 2010 a junho de 2011, em dois pontos (5 m e 15 m), utilizando uma rede otter trawl. Cerca de 19.500 indivíduos foram capturados com predominância de fêmeas (77,15%) e essas foram maiores que os machos indicando dimorfismo sexual. Houve inversão do paradigma latitudinal, onde os camarões apresentaram maiores tamanhos e longevidade quando comparados a outras regiões de maiores latitudes e isso provavelmente se deve às baixas temperaturas e alta produtividade primária. Apesar de não apresentar correlação estatística entre a abundância e os fatores ambientais, a espécie foi mais abundante em temperaturas próximas aos 20,0º C e nos meses com alta concentração de clorofila-a. Devido às características peculiares da região, os espécimens de A. americanus apresentarem diferenças em relação a tamanho e longevidade quando comparados aos indivíduos amostrados em outros estudos realizados na plataforma continental do sudeste brasileiro.

AbstractThe population dynamics of Acetes americanus was investigated, focusing on the sex ratio, individual growth, longevity, recruitment and relationship between abundance and environmental factors in the region of Macaé, strongly influenced by coastal upwelling. Otter trawl net samplings were performed from July 2010 to June 2011 at two points (5 m and 15 m). Nearly 19,500 specimens, predominantly females (77.15%), were captured. Their sizes, larger than that of males, indicated sexual dimorphism. Shrimps at lower latitudes present larger sizes and longer longevity than those from higher latitudes. This difference is probably due to low temperatures and high primary productivity. Though no statistical correlation was found between abundance and environmental factors, the species was more abundant in temperatures closer to 20.0º C and in months with high chlorophyll-a levels. Due to the peculiar characteristics of this region, A. americanusshowed greater differences in size and longevity than individuals sampled in other studies undertaken in the continental shelf of Southeast Brazil.

Este estudo analisa a ecologia de Lucifer faxoni Borradaile, 1915 em Ubatuba, São Paulo. Os indivíduos foram coletados mensalmente de julho de 2005 a dezembro de 2006, com uma rede de Renfro, arrastada por uma distância de 50 m, totalizando um esforço amostral de 50 m² em cada ponto de coleta. Nove pontos foram amostrados, variando de 1 a 15 m de profundidade. Cada 3 pontos foram agrupados em 3 zonas (Z1, Z2 e Z3). Os valores de salinidade, temperatura e pluviosidade foram registrados mensalmente em cada transecto. Os espécimes foram medidos quanto ao comprimento do somito pré-bucal (SL). Os resultados mostram que nas zonas mais rasas (Z1 e Z2) foram coletados 6306 indivíduos, enquanto que na mais profunda (Z3) obteve-se 3808 espécimes, não havendo diferença estatística entre as zonas (ANOVA, p=0.25). A abundância não diferiu estatisticamente entre as estações do ano (Tukey, p=0.02), exceto para a primavera. Em todas as estações amostradas, o sex ratio diferiu estatisticamente (χ², p< 0.05). Os fatores ambientais aqui analisados apresentaram relação estreita com a distribuição espaço-temporal de L. faxoni. A pluviosidade influenciou diretamente a salinidade, que provocou o deslocamento dos camarões L. faxoni para áreas mais profundas.

Luciferid shrimps have short life spans and a rapid turnover of generations, engage in sequential spawning, and protect their eggs during incubation. This study investigates the ecology of Lucifer faxoni Borradaile, 1915 in the littoral zone, Ubatuba region, São Paulo. Sampling was conducted monthly from July 2005 to December 2006 using a Renfro net trawled over a distance of 50 m for a total sampling effort of 50 m² at each station. Nine stations were sampled, ranging from 1 to 15 m deep. Three stations each were grouped into zones 1, 2 and 3 (Z1, Z2 and Z3). Monthly values of salinity, temperature and rainfall were recorded at each station. The pre-buccal somite length (SL) of each specimen was measured. The results showed that in shallower zones (Z1 and Z2), 6306 individuals were captured, whereas in the deeper zone (Z3), 3808 specimens were captured, but no significant differences in SL was detected between the specimens from Z1 and Z2 and those from Z3 (ANOVA, p=0.25). The abundance of shrimps did not differ significantly between seasons (Tukey's test, p=0.02) except in the spring. The sex ratio differed significantly over the seasons (χ², p<0.05). The results were closely associated with environmental factors with respect to the spatial and seasonal distribution of L. faxoni. Rainfall affected salinity directly, and contributed to the displacement of these shrimps to deeper areas.

The relationship between species abundance and environmental factors such as the bottom water temperature and salinity, the texture and organic matter content of the sediment and the distribution of Pleoticus muelleri and Artemesia longinaris were investigated. Specimens and samples of abiotic factors were collected monthly from May 2008 to April 2010 at 4 locations in Santos Bay on the southern coast of the State of São Paulo. A shrimp boat equipped with an otter-trawl net with an 8 m mouth aperture and a mesh size of 20 mm tapering to 18 mm at the cod end was used for sampling. Shrimp abundances were compared with an analysis of variance (ANOVA). However, when the data did not follow a normal distribution, we used the Kruskal-Wallis test. The relationship between environmental factors and the abundance of individuals was assessed with a Pearson's correlation. The largest catches of individuals of both species occurred in the late spring of 2008. The greatest abundance occurred at the outer part of the bay (collection point 4). The greatest abundance of P. muelleri was associated with lower temperatures and sediments with higher clay and organic matter content, whereas for A. longinaris, there was no significant correlation with any of the abiotic factors recorded. However, the occurrence of both species was related to lower bottom temperatures associated with the intrusion of the South Atlantic Central Water in the region.