Assessing the importance of burrows through behavioral observations of Parastacus brasiliensis, a Neotropical burrowing crayfish (Crustacea), in laboratory conditions

Alexandre V Palaoro,Marcelo M Dalosto,Cadidja Coutinho,Sandro Santos

doi:10.1186/1810-522x-52-4

Alexandre V Palaoro, Marcelo M Dalosto + Show 2 more

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https://doi.org/10.1186/1810-522x-52-4

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Journal: Zoological Studies	Publication Date: Aug 8, 2013
Citations: 31	License type: cc-by

Affiliation: Universidade Federal de Santa Maria

Abstract

Abstract Background Crayfish from the Neotropical region comprise a unique group among crustaceans. Their burrowing habits have severe consequences for many ecological, morphological, and behavioral traits. Although they are all considered true burrowers, the degree of these adaptations and their relationships to the behavioral repertoires of these crustaceans have been discussed for a long time, although with no consensus. Results To address this situation, we performed behavioral observations of Parastacus brasiliensis in a laboratory environment. Animals (n = 7) were isolated and acclimated in experimental aquaria according to their size (two large and five smaller aquaria) and observed for seven days at four different times of the day (twice during the day and twice at night). Their behaviors were qualified and quantified. The time spent inside and outside the burrow was also observed and analyzed with a t test for paired samples. Their circadian activity was analyzed using Rayleigh's Z test. Animals spent 54.9% of the time hiding within the burrow and also remained longer in it during the day than at night. They spent more time active outside the burrow during the night. Conclusions These results suggest that these crayfish are nocturnal and are definitely not a part of the lotic species group. This species appears to be closely associated with its burrow but can exhibit considerable activity outside of it and can therefore be classified as a secondary burrower. Although this is a laboratory study, the results may stimulate further studies on the importance of burrows to these animals and provide basic background information for new studies on these cryptic crustaceans.

Highlights

Crayfish from the Neotropical region comprise a unique group among crustaceans
They were transported to the laboratory, where the carapace length (CL; mean, 21.89 ± 2.5 mm, Table 1) was measured, and they were allowed to acclimate for 5 days in individual, opaque, 2-L aquaria with constant aeration, and were fed every 2 days
Burrow morphology seemed similar to those of type 1b, according to Horwitz and Richardson (1986). This type is usually associated with tertiary burrowers such as Procambarus clarkii (Huner 2002) and is relatively rudimentary compared to that of primary burrowers, such as P. defossus, which always has more than one branch and is deeper than those observed in this experiment (Noro and Buckup 2010)

Summary

Introduction

Crayfish from the Neotropical region comprise a unique group among crustaceans Their burrowing habits have severe consequences for many ecological, morphological, and behavioral traits. Crayfish are among the most widespread freshwater decapods, occurring naturally on every continent except Antarctica and continental Africa (Breinholt et al 2009) They occur in streams, rivers, lakes, caves, marshlands, and even in areas away from surface water (Nyström 2002; Richardson 2007). The species in these last situations are called burrowing crayfish, and they build extensive underground burrow systems, in which they spend most of their lives Even though burrowing species behave differently from other crayfish, very little is known about them mainly because their fossorial habits make sampling difficult (Punzalan et al 2001; Richardson 2007)

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