Influence of color and brightness on ontogenetic shelter preference by the prawn Macrobrachium rosenbergii (Decapoda: Palaemonidae)

The giant river prawn, Macrobrachium rosenbergii (de Man, 1879), is a species of great commercial importance. It is farmed under different conditions that translate to a great range of light environments, which impact their behavior and productivity. We present the first study employing both visual modeling and beha vioral data to evaluate the ontogenetic changes in color preferences of juveniles and adults of M. rosenbergii. We offered ten shelters of different colors to juveniles and adults and registered their preferences. Our results show that shelter preference changed with ontogeny: juveniles chose shelters based on chromaticity (preference for blue), while adults based their decisions on brightness (preference for dark grey). This preference adults show for dark colors is probably associated with light avoidance behavior. We recommend providing blue shelters for juveniles and dark shelters for adults.(AU)

Activity patterns and use of microhabitat in lizards of the genus Tropidurus in a urbanized area of Natal, Brazil / Padrões de atividade e utilização de micro-habitat em lagartos do gênero Tropidurus em espaço urbanizado de Natal, Brasil

This study analyzed sun exposure, substrate type selected, and various behaviors exhibited by the lizard Tropidurus during thermoregulation. Observation entailed thirty days in an urbanized area of Centro de Biociências/ Universidade Federal do Rio Grande do Norte. Their behavior was recorded using a scan sampling route and an instantaneous record method at three different time intervals (9am to 10am, 12am to 1pm, and 3pm to 4pm). Significant differences were seen with sun exposure (p = 0.027), with most lizards remaining in shadowed areas, where the animals preferentially remained standing (p 0.001). We were also able to observe more lizards in the following substrates: tile, wall, rocks, and bricks (p 0.001). In addition, the animals were in these substrates more frequently from 12am to 1pm (p = 0.004). (AU)

Analisamos a exposição solar, o tipo de substrato e os comportamentos exibidos por lagartos Tropidurus durante a termorregulação. Foram realizados 30 dias de observações nos horários 9h-10h, 12h-13h e 15-16h, através de amostragem por escaneamento, com registro instantâneo a cada um minuto, em um espaço urbanizado do Centro de Biociências/Universidade Federal do Rio Grande do Norte. Observamos diferença significativa quanto à exposição solar (P = 0,027), com a maior ocorrência de lagartos em áreas sombreadas, onde os animais preferencialmente permaneceram parados (P < 0,001). Observou-se maior frequência de lagartos em substratos compostos por telhas, paredes, rochas e tijolos (P < 0,001). Os animais tiveram maior ocorrência nesses substratos no horário 12h-13h (P < 0,05).(AU)

Activity patterns and use of microhabitat in lizards of the genus Tropidurus in a urbanized area of Natal, Brazil / Padrões de atividade e utilização de micro-habitat em lagartos do gênero Tropidurus em espaço urbanizado de Natal, Brasil

This study analyzed sun exposure, substrate type selected, and various behaviors exhibited by the lizard Tropidurus during thermoregulation. Observation entailed thirty days in an urbanized area of Centro de Biociências/ Universidade Federal do Rio Grande do Norte. Their behavior was recorded using a scan sampling route and an instantaneous record method at three different time intervals (9am to 10am, 12am to 1pm, and 3pm to 4pm). Significant differences were seen with sun exposure (p = 0.027), with most lizards remaining in shadowed areas, where the animals preferentially remained standing (p 0.001). We were also able to observe more lizards in the following substrates: tile, wall, rocks, and bricks (p 0.001). In addition, the animals were in these substrates more frequently from 12am to 1pm (p = 0.004).

Analisamos a exposição solar, o tipo de substrato e os comportamentos exibidos por lagartos Tropidurus durante a termorregulação. Foram realizados 30 dias de observações nos horários 9h-10h, 12h-13h e 15-16h, através de amostragem por escaneamento, com registro instantâneo a cada um minuto, em um espaço urbanizado do Centro de Biociências/Universidade Federal do Rio Grande do Norte. Observamos diferença significativa quanto à exposição solar (P = 0,027), com a maior ocorrência de lagartos em áreas sombreadas, onde os animais preferencialmente permaneceram parados (P < 0,001). Observou-se maior frequência de lagartos em substratos compostos por telhas, paredes, rochas e tijolos (P < 0,001). Os animais tiveram maior ocorrência nesses substratos no horário 12h-13h (P < 0,05).