Aspectos populacionais do bivalve perlífero Paxyodon syrmatophorus (Gmelin, 1791) (Bivalvia: Hyriidae) no rio Maratauíra, Pará, Amazônia Oriental.

Abstract

Paxyodon syrmatophorus (Gmelin, 1791) (Bivalvia: Hyriidae) is a freshwater mollusk, abundant in sandy-loamy bottoms of water bodies in the Amazon region. The present work aims to study aspects of population dynamics (eg, density, biomorphometry, growth and longevity) of P. syrmatophorus, present in a natural bank in the Maratauíra river (Abaetetuba - Pará), collected from September 2016 to September 2017. Additionally, the centesimal composition and perliferous efficiency of the species were estimated. The individuals presented a modal anteroposterior length of 53 to 68,9 mm, ranging from 7,71 to 104,63 mm, with population densities of 15 ind./m². The growth functions (K and L∞) of Von Bertalanffy were established from length frequency distributions and by the mark-recapture method using fluorochrome calcein. Thus, P. syrmatophorus has low growth rate (K = 0,10) and long-lived growth (L∞ = 83.62). With this, it is assumed that an individual with a length of 83,62 mm presents an age equivalent to 98 years, it is evident the efficacy of the method using the marker fluorochrome calcein. In addition, this work reports the use of P. syrmatophorus as a complementary food source by local residents who, through specific analyzes, present a high moisture and protein content in their composition, as well as low lipids and calories, presenting a mean of edible meat yield by 16.2%. It was also evidenced that, P. syrmatophorus presents as a species with potential for future pearl cultures in the region. In short, this study presents innumerable innovative information (and unique in the scientific literature) that enables future studies (e.g., reproductive biology, larval dispersal, etc.) with P. syrmatophorus and other freshwater bivalves. Consequently, favoring a possible sustainable management and / or protectionist measures of the species.