Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin

Abstract

Background: In inland water systems, it is important to characterize the trophic links in order to identify the 'trophic species' and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours. Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs. Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro-and microfauna.

Freshwater crabs (Decapoda: Pseudothelphusidae) increase rates of leaf breakdown in a neotropical headwater stream

“…Similarly, studies of trichodactylid crab gut contents have reported the consumption of plant detritus and insect larvae (e.g. Pirela & Rincón, 2013;Williner et al, 2014).…”

“…However, there have been some recent feeding ecology studies on trichodactylid crabs in South America (e.g. Pirela & Rincón, 2013;Williner, Carvalho, & Collins, 2014) that have found that crab gut contents predominantly include allochthonous plant material, as well as a wide trophic range of prey items. Costa et al (2016) documented higher survivorship of the caddisfly Triplectides sp.…”

Ghost shrimps (Decapoda: Axiidea: Callianassidae) as producers of an Upper Miocene trace fossil association from sublittoral deposits of Lake Pannon (Vienna Basin, Slovakia)

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Population structure, recruitment, and mortality of the freshwater crabDilocarcinus pageiStimpson, 1861 (Brachyura, Trichodactylidae) in Southeastern Brazil

“…Several biological and ecological aspects of freshwater decapod crustaceans are still scarce in the literature, such as trophic ecology, behavioral ecology, functional diversity, population dynamics studies, sex ratio, reproductive period, size at maturity, population delimitation, and the relation of the species with different environments (Davanso et al 2013;Herrera et al 2013;Sharma & Gupta 2013;Williner et al 2014). Approximately, 20% of brachyurans inhabit fresh waters (Yeo et al 2008), and they can be found on every continent .…”