Biologia reprodutiva dos equinóides Echinometra lucunter (Linnaeus, 1758) e Arbacia lixula (Linnaeus, 1758) na Ilha da Galheta, litoral paranaense, Brasil

The echinoids contribute expressively to the megabenthic biomass, and present high species diversity. They are important in tropical and temperate coastal ecosystems and might cause changes on the substrate and community structure. The knowledge of the ecological and biological characteristics of a species is useful tool to understand the life strategies of the marine invertebrates. The present work aims to describe some biological aspects of the echinoids Echinometra lucunter and Arbacia lixula related to the reproductive strategies. The work describes ecological relations (i.e. food habits and spatial distribution to access trophic interactions), reproductive patterns (i.e. gametogenesis extension and periodicity descriptions and the female gamete biometry) and metabolic behavior (i.e. resource allocation in different body compartiments) in both species. Samples were obtained monthly, from August 2000 to July 2002, along the north rocky shore of the Galheta Island (48°19’W 25° 35’S), in Paraná State coast. Twenty adults individuals of E. lucunter (71,2 mm test diameter average) and A. (45,5 mm) were collected manually by scuba divers. Temperature, salinity and water transparency were registered in situ, solar radiation data were obtained from Guaratuba Metereological Station at SIMEPAR. Qualitative and quantitative analysis of the food habit and nutritional state were estimated by gut content and repletion index (IR). The tests width of E. lucunter and Arbacia lixula were measured and their viscera were submitted to specific procedures. The gut content was identified, dried and weighted to determinate the IR and the ash free dry weight was determinated in order to obtain the organic matter content. Gonad microscopic analysis was used to describe the reproductive cycle. Histological procedures were applied to one gonad section (3,5 cm3). Gonadal development, sex ratio, mean diameter of the mature oocyte in maturation and spawning stages were recognized. The resources allocation strategies were analyzed by the differential contribution of the body compartments in the total body weight, through the determination of the carapace and associated tissues index (IC), Aristotle's lantern and associated musculature (IL), gonadal index (IG), gut index (IT) and the biochemistry composition (proteins, lipids and carbohydrate levels) of the gonads and gut. These biological variables were analyzed according to tissues, sex and month by analyses of variance (ANOVA). Correlations of body indexes and biochemistry levels were established with p<0,05 significance level. PCA multivariate analysis was used to describe the relations among the environmental features and biological variables associated to the reproductive cycle. Water temperature and transparency and light intensity showed seasonal patterns; salinity was higher than 30 throughout the whole study. E. lucunter was dominant in the upper level, showing a omnivorous habit, grazing mainly over the macroalgae phaephyta Padina gymnosphora. At the subtidal, the lower densities of A. lixula showed a homogeneous distribution indicates an omnivorous carnivorous adaptive diet. The gametogenesis cycle of E. lucunter was seasonal, gametes release occurred from the late summer throughout the