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Life‐cycle, drift and production of Gammarus pulex L. (Amphipoda) in a Danish spring
Author(s) -
IVERSEN TORBEN MOTH,
JESSEN JACOB
Publication year - 1977
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1977.tb01676.x
Subject(s) - gammarus pulex , amphipoda , sexual maturity , biology , dry weight , zoology , pulex , ecology , population , cohort , crustacean , demography , botany , mathematics , daphnia , statistics , sociology
SUMMARY.Gammarus pulex L. was studied at three sites in a Danish spring. Breeding took place during the summer and therefore cohorts could be followed. Sexual maturity was not reached until the next summer and maximum age appeared to be two years. Changes in population size differed between stations and was tentatively related to differences in drift and numbers of predators. Generally the drift was non‐selective between cohorts and within cohorts. Yearly production estimated from production curves was 2.6 g dry weight m −2 (the young cohort) and 1.2 g dry weight (the old cohort) at Station 1. The respective P /B̄ ratios were 3.35 and 1.22. Production of the youngest cohort at the three stations in the period September‐May was 0.9–1.3 g m −2 and P /B̄ ratios were 2.14–2.31. Total yearly production at the three stations was estimated at 4–7 g dry weight m −2 .