Effect of biological and anthropogenic sound on the orientation behavior of four species of brachyuran crabs

The settlement phase of crustaceans is critical and can ultimately affect their population structure. Underwater sound has been proposed as one of the most important sensory cues used by these animals during this phase because it can provide direction and habitat quality information. Here, we evaluated the effect of different acoustic signals (biological and anthropogenic) on the orientation response of different stages (megalopae and juveniles) of 4 brachyuran crabs (Cyrtograpsus angulatus, C. altimanus, Neohelice granulata, Leptuca uruguayensis) from Mar Chiquita coastal lagoon in Argentina. A binary choice chamber system was used, and different sound sources (crustacean, fish and motorboat signals) selected from recordings of the lagoon soundscape were reproduced. C. angulatus megalopae and juveniles responded positively towards crustacean signals, while juveniles responded negatively towards fish sounds. N. granulata juveniles orientated negatively towards crustacean, motorboat and fish signals. C. altimanus and L. uruguayensis juveniles did not respond to fish signals. The results support the idea that invertebrates can discriminate among conspecific signals and highlight the role of sound on prey-predator relationships. The behavioral orientation response to the motorboat sound evidences a presumably negative effect of anthropogenic sound on the biological interactions of species. This information is important, given the urgent need to increase knowledge about coastal marine lagoons to enhance their protection, especially considering the role of the key species of crabs in this habitat.</jats:p

Effects of temperature and irradiance on filament development of Grateloupia turuturu (Halymeniaceae, Rhodophyta)

Grateloupia turuturu Yamada is an economically valuable red alga with great potential in nutraceuticals and pharmaceuticals. Filaments of G. turuturu are of primary importance in germplasm preservation and sporeling culture, although filaments were not present in its life cycle. In this study, effects of temperature (10, 15, 20, 25, and 30 °C) and irradiance (10, 30, 60, and 90 μmol photons m−2 s−1) with photoperiod 10:14 h (light/dark) on filament development were investigated. Our results indicated that 25 °C was the optimal temperature for the formation of discoid crusts regardless of the irradiance. Conditions of 20 °C and 60 μmol photons m−2 s−1 promoted the development of discoid crusts and formation of upright thalli

Relative size-at-sex-change in parrotfishes across the Caribbean: is there variance in a supposed life-history invariant?

Invariant life-history theory has been used to identify parallels in life histories across diverse taxa. One important invariant life-history model predicts that, given simple assumptions and conditions, size-at-sex-change relative to maximum attainable body size (relative size-at-sex-change, RSSC) will be invariant across populations and species in sequential hermaphrodites. Even if there are broad pecies-wide limits to RSSC, populations could fine-tune RSSC to local conditions and, onsequently, exhibit subtle but important differences in timing of sex change. Previous analyses of the invariant sexchange model have not explicitly considered the potential for meaningful differences in RSSC within the confines of a broader ‘invariance’. Furthermore, these tests differ in their geographical and taxonomic scope, which could account for their conflicting conclusions. We test the model using several populations of three female-first ex-changing Caribbean parrotfish species. We first test for species-wide invariance using traditional log–log regressions and randomisation analyses of population-specific point estimates of RSSC