Length-weight allometric relationships in four crustaceans from Alberta lakes and ponds.

Abstract

The relationship between length and dry weight was studied in Branchinecta gigas Lynch, Branchinecta mackini Dexter, Eubranchipus bundyi (Forbes) (Anostraca), and Diaptomus nevadensis Light (Copepoda) from shallow lakes in Alberta. Two distinct allometric equations were required to accommodate changes in length–weight relationships during the life cycles of Branchinecta and were also found applicable to Diaptomus. All of these species batch as first nauplii. Their life cycles may therefore be described as consisting of two growth phases: a larval phase terminating upon attainment of the definitive adult number of segments and characterized by predominantly anamorphic growth in length, with exponents of 1.45 (B. gigas), 1.51 (B. mackini), and 1.74 (D. nevadensis); and a postlarval phase of more rapid increase in dry weight. During the latter phase, growth exponents were 3.24 in B. gigas, 2.36 and 2.57 respectively in male and female B. mackini, and 3.39 and 3.61 in D. nevadensis males and females. In contrast, a single equation with an exponent of 2.46 was found to be adequate for Eubranchipus bundyi, which passes through the first metanauplial stages enclosed within the blastoderm cuticle.