Baseline growth of the Trinidad freshwater crab Poppiana dentata (Randall, 1840) under laboratory conditions

Crescimento do caranguejo de água doce de Trinidad, Poppiana dentata (Randall, 1840), em condições laboratoriais

Abstract

Poppiana dentata (Randall, 1840) is widely distributed throughout riverine habitats in Trinidad. However, there is a scarcity of information on the biology of this species. This study provides the first baseline examination that describes growth aspects for P. dentata. Juvenile crabs were obtained from berried females collected in northwest Trinidad. Carapace width (CW), length (CL), moult incident, intermoult period and qualitative aspects were recorded for crabs (N = 23) over 9 months. CW, CL and intermoult period were used to derive percentage size increment, specific growth rate (SGR) and size at structural maturity for both sexes. Growth curves and logistic equations were also generated for each sex. Hatched crabs (< 5 mm CW) underwent rapid hardening after their first moult, indicating a fast turnover of moult cycles. SGR and CW percent increment were also the highest for this initial moult (P < 0.05). CW, CL, intermoult period, size increment and SGR did not differ between sexes (P > 0.05), with logistic equations expressed as CW = 32.81 (1+exp (1.481 ̵ 0.031t))^-1 for males and CW = 34.07 (1+exp (1.516 ̵ 0.027t))^-1 for females. Yet, breakpoint analyses indicated dissimilar sizes for structural maturity (male: 28.40 mm CW; female: 16.84 mm CW). These patterns reflect a shorter life span for this species in comparison to what has been reported for other trichodactylid relatives. This can have implications for P. dentata populations residing in anthropogenically disturbed habitats; thus, highlighting the need for conservation strategies to ensure preservation of native wild stock.

Keywords:  freshwater Trichodactylid; growth rate; Poppiana dentata; structural maturity