Inversión reproductiva de Aratus pisonii (Decapoda: Sesarmidae): diferencias entre hábitats y análisis de rutas

Abstract

Reproductive investment of Aratus pisonii (Decapoda: Sesarmidae): differences among habitats and path analysis. Aratus pisonii is an abundant Neotropical mangrove crab that forages on fresh leaf tissue in the canopy and lives in a wide spectrum of habitats. It presents great plasticity in some aspects of its life history becoming an excellent subject for comparative studies. The purpose of this study was to investigate possible reproductive variations among populations of this crab in mangroves with different levels of structural development, and explore the direct and indirect effects of environmental variables on reproductive investment. The study was conducted during the rainy season of 2003 and 2004, in North Western Venezuela. Fecundity (number of eggs/female), dry weight of egg mass (PSH) and egg quality (C/N eggs ) were evaluated in five populations of this species, in mangroves under different environmental conditions (estuarine, marine, hypersaline) and diverse degrees of structural development (arboreal, arbustive, scrub). Reproductive output (Ro) was obtained by the ratio Ro=PSH/dry body weight (PSC); other estimations of Ro were tested: Ro1=PSH/carapace length (CL), Ro2=fecundity/CL. A path analysis was used to explore causal relationships between environmental and morphological variables and reproductive investment (PSH, fecundity). Fecundity ranged from 6 463±831 eggs (Mean±SE) in the hypersaline arbustive mangrove to a maximum of 24 584±2 393 eggs in estuarine arboreal mangrove, which presents the greatest structural development. The reproductive output of females showed significant differences among mangroves, with the highest values of Ro1, Ro2 in the estuarine mangrove females. The results of the path analysis indicated a multicausal effect of morphological and environmental variables; in particular, the salinity showed the greatest influence on fecundity and PSH. The condition of the estuarine mangrove forests with lower salinity and higher structural development involving higher quality of mangrove leaves and a wider range of potential resources, may explain the higher reproductive output of females observed in this habitat. Rev. Biol. Trop. 63 (2): 385-399. Epub 2015 June 01.

Can contrasting environmental conditions of mangroves induce morphological variability in <em>Aratus pisonii</em> (Crustacea: Brachyura: Sesarmidae)?

“…Recent studies confirm that the variety of resources consumed by A. pisonii is closely related to the structural development of the mangroves where they live (López and Conde 2013). Moreover, it has been found that the reproductive performance of this species responds to a gradient of structural complexity of the mangroves, and that fertility and the weight of the egg mass are correlated equally with the size of the crab, as well as with the environmental variables (salinity and structural development of the mangrove) (López-Sánchez and Quintero-Torres 2015).…”

“…1), while in Paraguaná Peninsula, where rainfall is the only source of freshwater for the mangroves, there is only a short rainy period that usually last from October to November, in a predominantly dry climate with a long period of drought (Conde 1990); the rainfall is the only source of freshwater for the mangroves of the Paraguaná Peninsula. For more details about this study area, see López et al (2011) and López-Sánchez and Quintero-Torres (2015).…”