AB 8:1-13 (2009)  -  DOI: https://doi.org/10.3354/ab00195

Overlap in the distributions between indigenous and non-indigenous decapods in a brackish micro-tidal system

Erin Breen1,2,*, Anna Metaxas1

1Department of Oceanography, Dalhousie University, 1355 Oxford St., Halifax, Nova Scotia B3H 4J1, Canada
2Present address: Ministry of Fisheries, PO Box 12034, Napier 4110, New Zealand

ABSTRACT: In the Bras d’Or Lakes, Nova Scotia, Canada, the vertical distributions and abundances of the non-indigenous Carcinus maenas and the indigenous Cancer irroratus and Dyspanopeus sayi were quantified at 4 sites (to a maximum depth of 3.5 m in 2005), in 3 seasons (spring, summer and fall), in each of 2 years (2005, 2006). All species overlap spatially and temporally at 0.5 m in all seasons and years, indicating a strong potential for biotic interactions (e.g. habitat use, prey consumption). All species, particularly the juvenile stages, were most abundant at shallow (≤1.5 m) depths and were strongly associated with cobble and cobble-composite substrates. C. maenas and D. sayi abundances were also strongly correlated at shallow depths in Benacadie, Ross Ferry and Kempt Head. In 2006, when winter water temperatures were ~1 to 4°C warmer than in 2005 (at which time winter water temperatures were <0°C and ice coverage was extensive), the abundances of C. maenas and D. sayi were ~1.5- to 10-fold higher, and pronounced pulses in recruitment were observed. The abundance of C. irroratus was low (<0.125 individuals m–2) in Benacadie (compared to C. maenas and D. sayi, at 0.5 to 10 individuals m–2), where salinity regularly falls below 20, a level which is outside the preference and tolerance of C. irroratus. Inter-annual differences in water temperatures may influence the survival and abundance of both indigenous and non-indigenous species, which could, in turn, modify biotic interactions among these species.

KEY WORDS: Carcinus maenas · Cancer irroratus · Dyspanopeus sayi · Population dynamics · Temperature · Bras d’Or Lakes

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Cite this article as: Breen E, Metaxas A (2009) Overlap in the distributions between indigenous and non-indigenous decapods in a brackish micro-tidal system. Aquat Biol 8:1-13. https://doi.org/10.3354/ab00195

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