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.

Marine amphipods as a new live prey for ornamental aquaculture: exploring the potential of Parhyale hawaiensis and Elasmopus pectenicrus

“…For E. pectenicrus , to the best of our knowledge, no previous information is available, but for a closely related species, Elasmopus levis , 22.3 ± 2.1 (standard error) embryos per female were reported, which is over a three-fold difference ( Borowsky, 1986 ). The fecundity values obtained are lower than those reported for cultured (36.3 eggs/embryos per female in C. scaura in average) ( Baeza-Rojano et al, 2013a ) and wild caprellids (from 2 to 55 in Pseudaeginella montoucheti and from 2 to 13 eggs in P. tenuis ) ( Garcia, Cunha & Jacobucci, 2019 ). Caprellids, unlike gammarids, show a relatively sedentary behavior (low energy expenditure) that could explain their higher fecundity; however, the active behavior of gammarids could be advantageous stimulating feeding responses, as previously observed when feeding S. officinalis hatchlings ( Baeza-Rojano et al, 2010 ).…”

Population biology of sympatric species of Caprella (Amphipoda: Caprellidae) in a tropical algal bed

“…The sex ratio deviated for males as recorded in this study was already observed for other caprellid species, such as Paracaprella tenuis Mayer, 1903and Pseudaeginella montoucheti Quitete, 1971(Garcia et al 2019. The predominance of males suggests an intraspecific competition for females (Powell and Moore, 1991).…”

“…According to De Paula et al (2016), the reproductive biology evaluation of the caprellid amphipods of Lázaro Beach indicated a more intense reproduction in autumn and winter. Other caprellid species, such as Paracaprella tenuis and Pseudaeginella montoucheti, which were recorded in the same area as the present study, showed higher densities in winter (Garcia et al 2019). This indicates possible competitive interactions among those caprellids and Caprella species.…”

“…Males of all Caprella species reached larger mean size than females, as is usual for many other caprellids (Guerra-García et al 2011, Lolas and Vafidis 2013, Garcia et al 2019. This sexual dimorphism can be related to different energy allocation for growth and the existence of aggressive behaviour between males before copulation (Caine 1991).…”

“…All caprellids were measured (total length) under a stereomicroscope with an ocular micrometer with constant magnification. For each specimen, the body segments were individually measured and summed to obtain the total length (mm) (Garcia et al 2019).…”