Temperature control on the post-embryonic growth of Neomysis intermedia Czerniawsky in a hypereutrophic temperate lake

Abstract

In situ growth of N. intermedia Czerniawsky at the post-embryonic stage was studied by the cohort analysis using the probability graphic technique in a hypereutrophic temperature lake, Lake Kasumigaura [Japan]. Two overwintering populations and 5 spring cohorts were recognized over 2-yr field observations performed at 4-15 day intervals. There was no luck in following possible cohorts in mid-summer and autumn. The specific growth rate of the post-embryonic stage determined varied between 0.001 and 0.16 (day-1) depending upon the surrounding water temperature, and each individual growth showed an almost exponential pattern. Average size of newly hatched individuals was .apprx. 2.1 mm in body length and was consistent regardless of the difference of seasons; however, the average mature size was highly temperature-dependent, ranging between 7.6 and 12.0 mm for males and 8.1 and 13.5 mm for females.