Population biology of Ampithoidae species (Crustacea, Amphipoda) associated with Sargassum filipendula (Phaeophyta, Fucales), at Fortaleza beach, Ubatuba, São Paulo, Brazil

The population biology of three species of the family Ampithoidae (Ampithoe ramondi, Cymadusa filosa e Sunampithoe pelagica) associated with Sargassum filipendula at Fortaleza beach, northern coast of São Paulo state was investigated from June 2000 to May 2001. The amphipods were identified, counted and separated in size classes through a nested sieve set. Month hystograms were obtained for juveniles, males and females. The ampithoid sex ratio was determined monthly. The reproductive biology of the species was evaluated by the relative frequency of ovigerous females, fecundity, average egg volume and correlation analysis between head lengh of ovigerous females and number of eggs in its brood pouch. Ampithoe ramondi was the most abundant species. The higher densities of the three species occurred in spring and summer. The sex ratio presented a significant difference from 1:1 only for A. ramondi (1:1.2; x² = 4.37; g.l. = 1; p < 0.05). Ovigerous females were registered for almost all the sampling periods. A positive correlation between the female head lengh and the number of eggs were only registered for A. ramondi (r&sup2; = 0.27; p < 0.05; n = 33). Cymadusa filosa showed the greatest fecundity and egg volume.A biologia populacional de três espécies de anfípodes da família Ampithoidae (Ampithoe ramondi, Cymadusa filosa e Sunampithoe pelagica) associadas a Sargassum filipendula da Praia da Fortaleza, litoral norte do Estado de São Paulo foi estudada entre junho de 2000 e maio de 2001. Os anfípodes foram identificados, contados e separados em classes de tamanho através de um conjunto de peneiras agrupadas. Foram obtidos histogramas mensais de jovens, machos e fêmeas. A razão sexual dos ampitoídeos foi avaliada mensalmente. A biologia reprodutiva das espécies foi avaliada através freqüência relativa mensal de fêmeas ovígeras, de sua fecundidade, volume médio dos ovos e correlação do tamanho da cabeça com o número de ovos contidos em seus marsúpios. Ampithoe ramondi foi a espécie mais abundante. As maiores densidades para as três espécies ocorreram na primavera e no verão. A razão sexual apresentou diferença significativa de 1:1 apenas para A. ramondi (1:1,2; x² = 4,37; g.l. = 1; p < 0,05). Fêmeas ovígeras foram registradas em quase todos os períodos de amostragem. Correlação positiva baixa entre o tamanho da cabeça da fêmea e o número de ovos contidos na bolsa incubadora foi registrada somente para A. ramondi (r&sup2; = 0,27; p < 0,05; n = 33). Cymadusa filosa apresentou a maior fecundidade e o maior volume dos ovos.12071216Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Population and reproductive biology of two caprellid species (Crustacea: Amphipoda) associated to Sargassum cymosum (Phaeophyta: Fucales) on the southeast coast of Brazil

Abstract Caprellid amphipods are common crustaceans at Sargassum beds of southeastern Brazil and constitute an important link between primary producers and marine consumers. The goal of this study is to evaluate population and reproductive biology of two caprellid species: Paracaprella tenuis Mayer, 1903 and Pseudaeginella montoucheti Quitete, 1971. Sargassum cymosum Agardh, 1820 samples were collected monthly between October 2010 and September 2011 in a rock shore in southeastern Brazil. The caprellids were identified, counted, measured and classified as males, immature females, sexually mature females, ovigerous females and juveniles. Eggs were counted and measured. Higher densities of P. tenuis and P. montoucheti were found mainly in winter and lower densities in fall and summer. Density variation is probably related to organic matter supply and substrate availability. Both species showed continuous reproduction with reproductive peaks. Pseudaeginella montoucheti larger egg volume indicates a longer incubation period. The egg volume was directly related to female size. The number of eggs was weakly related to female size, indicating that fecundity may be driven by other factors, such as the physiological conditions. Sex ratio deviated for males suggests a higher longevity of males. The present study highlighted important data of two caprellids species that occur in algal beds of different regions

Influence of a narrow depth gradient on the spatial structure of Sargassum peracarid assemblages in Southeastern Brazil

A depth gradient may influence both macrophytes and their associated epiphytic community through variations in hydrodynamics and light conditions, which in turn may affect the mobile organisms living on them. We investigated how a narrow depth gradient affects the associated peracarid assemblages in a Sargassum cymosum bed. This study was conducted on a rocky shore in Southeastern Brazil. A 20x3m sampling area was defined parallel to the shore line, within which three perpendicular transects were sampled in October 1997 (spring), January 1998 (summer), April 1998 (fall), and July 1998 (winter). In each transect, three samples of Sargassum were randomly collected at three different depthsshallow (1m), intermediate (2m), and deep (3m). Peracarid fauna was identified, quantified, and classified into feeding groups. Depth affected both species richness and total density only in January, with fewer species and individuals at the shallow depth, more species at the intermediate depth, and more individuals at the deep depth. The taxonomic and feeding group composition of peracarid assemblages were also affected by depth, with differences depending on the sampling period. Herbivores and omnivores were commonly more abundant at the shallow depth, while detritivores were more abundant at the deep depth. Carnivores seemed not to be affected by depth. Small-scale distribution patterns can be related to how peracarid species deal with the variability in turbulence and food availability imposed by a depth gradient, with morphological attributes and feeding habits guiding how species are distributed in the space and thus the peracarid assemblage as a whole49210011011CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorCNPQ - Conselho Nacional de Desenvolvimento Científico e Tecnológicosem informação300337/82–5A scholarship grant to GBJ was provided by CAPES – “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.” Financial support for FPPL was provided by CNPq – “Conselho Nacional de Desenvolvimento Técnico e Científico” (300337/82–5). We also thank FAEPEX – “Fundo de Apoio ao Ensino, Pesquisa e Extensão,” which partially funded this researc

Habitat selection and potential antiherbivore effects of Peucetia flava (Oxyopidae) on Solanum thomasiifolium (Solanaceae)

Volume: 37Start Page: 365End Page: 36