Ashjian, C.J. & K.F. Wishner. (1993). Temporal and spatial changes in body size and reproductive state of Nannocalanus minor (Copepoda) females across and along the Gulf Stream. Journal of Plankton Research. 15(1):67-98.

71670

10.1093/plankt/15.1.67 [view]

Ashjian, C.J. & K.F. Wishner

1993

15(1):67-98.

Publication

Available in Wilson Copepod Library (non-digital)

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The temporal and spatial trends of cephalothorax length and reproductive state of adult females of the cosmopolitan copepod species Nannocalanus minor are described across the Gulf Stream near Cape Hatteras. NC. Consistent regional differences and a cross-stream gradient in size were found, with the largest animals in the Slope Water, animals of intermediate size in the Gulf Stream and the smallest animals in the Sargasso Sea. Distinct seasonal patterns in size were observed within each cross-stream region (Slope Water, Gulf Stream and Sargasso Sea) and these patterns followed seasonal changes in environmental conditions (temperature and sea surface pigment concentration). Body sizes of the Slope Water animals were inversely and linearly related to temperature with no clear relationship to sea surface pigment concentration, while body sizes of the Sargasso Sea animals were correlated with pigment concentration (asymptotic, non-linear relationship) with no relationship to temperature. The lack of consistent regional and seasonal trends in reproductive state suggested that continuous reproduction was a life history trait for adults of this species. The potential effect of short-term, episodic events on the size distribution and reproductive state of this species was investigated across and along a Gulf Stream meander during the BIOSYNOP project in 1988. Upwelling of nutrients may occur on the trailing flank of a meander, with enhanced primary and, possibly, secondary production occurring downstream in the leading flank of the meander. No specific meander effect was observed for body size. More individuals were reproducing downstream of the upwelling region, suggesting a response to the enhanced primary production characteristic of the upwelling region.

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