Relative abundance and habitat association of three crayfish (Orconectes virilis, O. rusticus, and O. immunis) near an invasion front of O. rusticus, and long-term changes in their distribution in Lake of the Woods, Canada

Wolfgang Jansen,Gavin Olson,Nola Geard,Tom Mosindy,Michael Turner

doi:10.3391/ai.2009.4.4.9

Abstract

We documented the abundance and habitat association of the native virile crayfish [Orconectes virilis (Hagen, 1870)] and two invasive species, the rusty crayfish [O. rusticus (Girard, 1852)] and the papershell crayfish [O. immunis (Hagen, 1870)] in a 38 km 2 area in the Lake of the Woods (LOW; Canada). From 20 June to 1 September in 2006, traplines were set at 376 sites for approximately 24 hours. A total of 9833 crayfish were captured, of which 68% were O. virilis, 23% were O. rusticus, and 9% were O. immunis. The mean catch per unit effort (CPUE) was 4.4 crayfish per trap with a maximum of 29. At least one invasion front of O. rusticus was detected, where its CPUE decreased sharply from a mean of 1.3 to 0.03. The mean CPUE of both O. virilis and O. immunis was significantly higher outside than within the front. For the entire catch, CPUE values of all thr ee species were negatively correlated. Water depth (0.5-12 m) was significantly related to crayfish abundance, positively for O. virilis and negatively for O. rusticu s and O. immunis. The distribution and abundance of the two invasive species on islands and adjacent mainland sites indicated that water depths near and deeper than the thermocline limit the colonisation of islands by O. rusticus and, particularly, O. immunis, but that islands surrounded by shallower water may serve as shortcuts in crayfish expansion circumventing convoluted shorelines. Mean CPUE of all three crayfish species differed between bottom substrates, being highest on mainly rocky substrates for O. virilis and O. rusticus, and on organic and inorganic fines for O. immunis. Mean CPUE of O. virilis near macrophytes was similar to that in areas free of aquatic plants; CPUE near macrophytes was significantly lower for O. rusticus and significantly higher for O. immunis. In conjunction with crayfish captures during lake-wide fish surveys between 1973 and 2006, we show that by 2006 O. rusticus has spread into most parts of LOW since its first record from Long Bay on the east side of the lake in 1963, expanding its distribution by an average of 2.1 km per year. Our results further indicate that O. immunis is more widespread and more abundant in LOW than previously assumed.

Highlights

IntroductionRecent interest in the ecological impacts and associated economical costs of nonindigenous organisms, including aquatic invasive species (AIS) (Pimentel et al 2000; Colautti et al 2006), and recognition of the impacts of invasive crayfish (Berrill 1978; Lodge and Lorman 1987; Gherardi 2007) have lead to a growing concern for the potential effects of introduced crayfish in North America and Europe (Momot 1996; Harlioglu and Harlioglu 2006; Rosenberg et al, in press)
With a mean catch per unit effort (CPUE) of 3.0 individuals per trap, the native O. virilis was the most abundant species overall but throughout the study area clusters of sites existed where mainly O. rusticus, and O. immunis occurred at the highest relative abundance
The CPUE of O. virilis in Lake of the Woods (LOW) is higher than reported from other studies

Summary

Introduction

Recent interest in the ecological impacts and associated economical costs of nonindigenous organisms, including aquatic invasive species (AIS) (Pimentel et al 2000; Colautti et al 2006), and recognition of the impacts of invasive crayfish (Berrill 1978; Lodge and Lorman 1987; Gherardi 2007) have lead to a growing concern for the potential effects of introduced crayfish in North America and Europe (Momot 1996; Harlioglu and Harlioglu 2006; Rosenberg et al, in press). The native range of O. immunis includes southern Ontario (Crocker and Barr 1968), but not other areas of the province (Winterton 2005). The papershell crayfish appears to be native to southern Manitoba, where it was first recorded in 1969 (Popham and Hancox 1970). This species seems to be well established in the Red River drainage, but does not occur in the far eastern part of the province O. immunis is an AIS in Europe where it was first reported as a likely aquarium release in south-west Germany (Geiter 1998; Dehus et al 1999) and where it has since spread north and southwards along the Rhine River corridor (Gelmar et al 2006)

Methods

Results

Conclusion