Fitness-associated consequences of an omnivorous diet for the mangrove tree crab Aratus pisonii

Me Riley,M Vogel,Bd Griffen

doi:10.3354/ab00543

Abstract

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 20:35-43 (2014) - DOI: https://doi.org/10.3354/ab00543 Fitness-associated consequences of an omnivorous diet for the mangrove tree crab Aratus pisonii Megan E. Riley1,*, Margaret Vogel2, Blaine D. Griffen1,2 1Department of Biological Sciences, and 2Marine Science Program, University of South Carolina, Columbia, South Carolina 29208, USA *Corresponding author: riley.megan.e@gmail.com ABSTRACT: Omnivory is a widespread trophic strategy with variable impacts on survival and reproduction, even within closely related taxonomic groups. In coastal ecosystems experiencing extensive environmental changes, many decapod crustaceans employ omnivorous feeding strategies. Because animals initially respond to environmental changes with behavioral modifications that can alter their foraging habits, a mechanistic understanding of how diet influences fitness is essential to predict the impact of future environmental changes on species fitness and population dynamics. We investigated the impact of an omnivorous diet on the consumption, survivorship, physiological condition, and reproductive effort of the mangrove tree crab Aratus pisonii, a major mangrove consumer. A. pisonii engaged in compensatory feeding on plant material; crabs consumed more food and digested it less efficiently as the proportion of plant material in their diet increased. Although there were relatively few deaths, survival appeared to be negatively impacted by the consumption of large quantities of animal material and marginally negatively influenced by high levels of plant consumption. Physiological condition improved due to consumption of both plant and animal material, while only consumption of animal material increased reproductive investment. These results demonstrate that the opportunistic inclusion of animal material in the diet of A. pisonii significantly improves physiological condition and reproductive effort, and suggests that vitellogenic individuals cannot fully compensate for a lack of animal material in their diet by increasing plant consumption. This study provides a mechanistic framework to understand how potential diet changes by omnivorous crabs such as A. pisonii, which are facing numerous changes in their environment, may impact their fitness and population dynamics. KEY WORDS: Diet · Opportunistic omnivory · Environmental change · Fitness · Reproduction · Crustacean Full text in pdf format PreviousNextCite this article as: Riley ME, Vogel M, Griffen BD (2014) Fitness-associated consequences of an omnivorous diet for the mangrove tree crab Aratus pisonii . Aquat Biol 20:35-43. https://doi.org/10.3354/ab00543 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 20, No. 1. Online publication date: January 13, 2014 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2014 Inter-Research.

Highlights

Omnivory is a widespread feeding strategy seen in a diverse range of taxa
We investigated the impact of diet quality and diet quantity on the feeding strategy, physiological condition, and fitness of the mangrove tree crab
A. pisonii demonstrated strong evidence of compensatory feeding on plant material when maintained in abundant food conditions by increasing their food consumption as mean daily consumption of (A) plant and (B) ani-mal material

Summary

Introduction

Omnivory is a widespread feeding strategy seen in a diverse range of taxa. Invertebrates such as insects (Coll & Guershon 2002) and crustaceans (e.g. Buck et al 2003, Poon et al 2010) commonly consume both plant and animal material. The presence of the invasive Asian shore crab Hemigrapsus sanguineus forced the European green crab Carcinus maenas, a previously established invader, to decrease its mussel consumption and increase its consumption of red algae, a less preferable food source (Griffen et al 2008). This foraging shift to an algal-dominated diet is concurrent with reduced fecundity in C. maenas, and is likely a contributing factor to the regional replacement of C. maenas by H. sanguineus (Griffen et al 2011)

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