Variaciones estacionales en el tamaño corporal y dieta de la estrella de mar Astropecten marginatus (Paxillosida, Astropectinidae) frente a la costa de Paraná, sur de Brasil

Abstract

Abstract:The sea star Astropecten marginatus has a neotropical distribution and is a highly abundant and frequent species in shrimp trawling by-catchin many places along the Brazilian coast. This has caused its threat to extinction and in addition, its bio-ecological aspects are poorly known. Thus, the main objective of this study was to analyze the seasonal variations of population length structure and feeding habits of the sea stars A. marginatus inhabiting off state of Paraná, Southern Brazil. The analyzed specimens were collected in February (summer), April (fall), June (winter) and October (spring) of 2008 from shrimp by-catch trawling. in the laboratory, each individual had its length measured and then weighed on an analytical scale. Afterwards, the stomach contents of 10 individuals of each of two most frequent length classes were seasonally analyzed. The relative frequency and abundance for each prey category was determined and, then combined into an index of alimentary importance. A total of 994 individuals of A. marginatus were collected with length ranging from 7.0 to 56.2mm, but most individuals were in the 20.1-25mm length classes. individuals larger than 40mm were only collected in the spring while a few recruits (<10mm) were found in fall and winter. The total weight of individuals ranged from 0.1 to 15.3g and the weight-length relationships showed a negative allometric growth (b<2.54). Regarding its food consumption, this sea star explored eleven food items, with cumaceans and mollusks as the most frequent items. High frequency of empty stomach was recorded at fall. Seasonal differences in the amount explored preys and ingested items as well as in the prey composition were also observed. Higher amount of explored prey categories and ingested items were recorded at winter-spring than summer-fall periods. Predominance in prey category changed from gastropods (summer and fall) to cumaceans (winter and spring). The importance of gastropods as main prey category at summer and fall should be carefully considered since it was coincidently observed with high frequency of empty stomach and low amount of ingested items. The observed seasonal differences in feeding behavior pattern were mainly associated to low prey availability and to changes in the sea star feeding rates, and probably reflected in some biological traits such as small body size of the population inhabiting waters off the Paraná coast, Southern Brazil. Rev. Biol. Trop. 62 (1): 59-68. Epub 2014 March 01.

Selective Feeding by a Predatory Sea Star Across a Depth Gradient in Northern Patagonia, Chile

“…Species can exhibit seasonal changes in their feeding behavior in response to temporal variation in biotic parameters (e.g., density, energy content of prey) and abiotic factors (e.g., substratum, temperature) (Christensen, 1970;Kreiling et al, 2020). Such changes in diet, feeding preferences and foraging behavior have been reported for other sea stars [e.g., Asterias rubens (Castilla, 1972); Luidia clathrate (McClintock and Lawrence, 1985); Astropecten marginatus (Guilherme and Rosa, 2014)], due possibly to seasonal variations in the nutritional value of prey (e.g., reproductive condition) that might lead to prey switching by predators (Krebs et al, 1977;Ostfeld, 1982) or seasonal changes in energetic requirements of sea star predators (Aguera et al, 2012). Such possibilities certainly exist, but both studies were only conducted over 4-month periods, and thus temporal variability in the diet could not be assessed.…”