Neotropical freshwater crabs (Decapoda: Pseudothelphusidae) shred leaves

Abstract

Freshwater crabs are macroconsumers that are commonly found in Neotropical headwater streams that may play a key role in energy flow and nutrient cycling in detrital food webs. Although studies have examined the feeding habits of trichodactylid crabs, little is known of this behavior in pseudothelphusid species, and specifically whether they actually consume leaf material. We conducted three nine-day laboratory trials with pseudothelphusid crabs (Ptychophallus tumimanus (Rathbun, 1898)) and leaves (Koanophyllon pittieri) to investigate whether crabs shred leaves. We hypothesized that leaf mass loss would be faster with crabs present relative to control tanks with only leaves. Leaf mass loss was significantly higher (p < 0.001) in tanks with crabs (0.49 ± 0.07 g, mean ± 1 SD) compared to control tanks (0.31 ± 0.05 g). We observed crabs manipulating, shredding, and consuming leaves, with leaf fragments and egesta present in tanks with crabs but not in control tanks. Their consumption and egestion activity may affect nutrient availability and transformation by stimulating microbial activity during leaf breakdown and converting coarse particulate organic matter (CPOM) to fine particulate organic matter (FPOM). Therefore, freshwater crabs need to be considered when studying energy flow and nutrient cycling in detrital food webs of Neotropical headwater streams.

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

“…This may be because crab manipulation of food with their chelipeds, mouthparts, and digestive structures (including a gastric mill that macerates food particles) results in most organic matter reaching their guts in the form of fine particulate organic matter, regardless of the original form (Alves, Abrunhosa, & Lima, 2010;Costa et al, 2016). Although we did not observe the mechanisms by which crabs increased leaf breakdown rates in this study, in a separate laboratory leaf feeding experiment with crabs from the same study stream, we observed crabs manipulating and ingesting leaves, and saw evidence of the egestion of leaf material (Yang, Wehrtmann, Wenger, & Rugenski, 2020). This suggests that at least some of the accelerated leaf breakdown in our crab enclosures was due to direct consumption.…”

Variations in Benthic Macroinvertebrate Communities and Biological Quality in the Aguarico and Coca River Basins in the Ecuadorian Amazon

“…Information on the traits of each macroinvertebrate was congregated from various databases [27,[69][70][71][72][73][74][75]. As each taxon was identified to the family level, which is of a higher level than the one most often given in the trait database, the traits of the most dominant and/or common species found were used as identified by the taxonomy expert.…”

Contribución al conocimiento de los cangrejos (Meiura: Decapoda) de la Colección CEBUC, con registros adicionales en Colombia

“…El grupo está compuesto principalmente por camarones, langostas y cangrejos, los cuales son considerados fundamentales en la dinámica de los ecosistemas (Ardila et al, 2002;Cumberlidge et al, 2009). Entre las funciones ecológicas que desempeñan, se destacan: la capacidad de acelerar los procesos de descomposición de la materia orgánica, a partir de los hábitos omnívoros y detritívoros de algunas especies (Arias-Pineda y Realpe, 2014; Arroyave-Rincón et al, 2017;Campos, 2014;Yang et al, 2020), su papel como reguladores poblacionales de herbívoros que favorece la producción primaria y secundaria en ambientes marinos y costeros (Giorgini et al, 2019;Gittman y Keller, 2013), a su vez son una fuente de alimento importante para diferentes especies de anfibios, aves, mamíferos y reptiles (Cognetti y Magazzú, 2001;Magalhães, 2001;Rivera-Pérez et al, 2020), son utilizados como bioindicadores de diferentes tipos de contaminación y calidad del agua (Campos y Lasso, 2015;Pinheiro et al, 2021) y también son considerados una base económica importante para las poblaciones humanas costeras (Cardona et al, 2019;Hernández-Maldonado y Campos, 2015). Además, existen especies de interés médico por ser vectores secundarios de tremátodos, como los representantes del género Paragonimus (Phillips et al, 2019) y se destaca la presencia de especies invasoras, que pueden causar importantes desequilibrios en los ecosistemas naturales (Arias-Pineda y Rodríguez, 2012;Camacho-Portocarrero et al, 2021).…”