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Hydrobiologia (2010) 652:289297 DOI 10.1007/s10750-010-0360-2
PRIMARY RESEARCH PAPER
Species-specic PCR discrimination of speciesof the calanoid copepod Pseudocalanus, P. acuspes and P. elongatus, in the Baltic and North Seas
Sabine Grabbert Jasmin Renz
Hans-Jrgen Hirche Ann Bucklin
Received: 16 March 2010 / Revised: 4 June 2010 / Accepted: 19 June 2010 / Published online: 2 July 2010 Springer Science+Business Media B.V. 2010
Abstract Two species of the calanoid copepod Pseudocalanus, P. acuspes and P. elongatus, have been reported from the Baltic and North Seas. Morphometric analysis based on Frost (Can J Zool 67:525551, 1989) did not identify the species in samples collected during the German GLOBEC program; the majority of measurements fell outside reported ranges for Baltic and North Sea specimens. A multiplexed species-specic PCR (SS-PCR) protocol was designed from a *700 bp sequence of mitochondrial cytochrome oxidase I (mtCOI), with primers designed to amplify regions of different sizes for the two species to allow detection by gel electrophoresis. The accuracy and reliability of the multiplexed SS-PCR reaction was conrmed by sequencing the mtCOI region. Preliminary SS-PCR analysis of geographic distributions of the two species indicated
that P. acuspes occurred exclusively at sampling sites in the Baltic Sea, whereas P. elongatus was found in the southern North Sea and at one site in the Baltic. The SS-PCR protocol can be used for routine identication of the two species for studies of population, community and ecosystem dynamics.
Keywords Pseudocalanus SS-PCR
Morphometric analysis Baltic and North Seas
Introduction
Copepods of the genus Pseudocalanus are common in temperate and boreal pelagic ecosystems of the northern hemisphere. Due to their high abundance, they play an important role in the trophic ecology of marine systems (Corkett & McLaren, 1978) by constituting major parts in the nutrition of adult sh and sh larvae. Despite the marked similarities in morphology, the congeneric Pseudocalanus species have shown consistent differences in life history, reproductive biology and bio-physical responses in regions where multiple species co-occur. For example, differences in reproductive biology and ecology have been found among co-occurring species in the Gulf of Alaska (Napp et al., 2005), southern Japan Sea (Yamaguchi et al., 1998), Bedford Basin (McLaren et al., 1989) and Georges Bank (Bucklin et al., 2001; McGillicuddy & Bucklin, 2002). These differences clearly show...