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Diel abundance, migration and feeding of fish larvae (Eleotridae) in a floodplain billabong
Author(s) -
Gehrke P. C.
Publication year - 1992
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1992.tb02617.x
Subject(s) - biology , diel vertical migration , larva , plankton , ichthyoplankton , biological dispersal , nocturnal , zooplankton , abundance (ecology) , ecology , population , demography , sociology
Eleotrid larvae (2.1–16 mm) were collected from surface waters of a billabong in south‐eastern Australia. Estimates of larval density in plankton net samples at night averaged 148.3 larvae per m 3 and 16.6 larvae per m 3 during the day. In contrast, pump samples provided density estimates of 8.3 larvae per m 3 at night and 0.9 larvae per m 3 during the day. Larval densities did not differ between open water, snag (fallen tree) and Typha habitats, but Typha habitats yielded larger larvae than other habitats. 32.9% of larvae in pump samples were damaged and unmeasurable, creating a bias favouring larger larvae. The modal length of larvae in net samples at night was 5–6 mm, compared with 3–4 mm during the day, reflecting both greater net avoidance by larger larvae during the daytime and dispersal of smaller larvae from the surface at night. Dispersion patterns of larvae suggest that classes of larvae smaller than, and larger than 5.0 mm exhibit reciprocal diel vertical migration behaviour linked to ontogenetic changes in diet. Larvae less than 5 mm fed only during the day and preyed exclusively on rotifers, whereas larger larvae continued to feed at night and consumed mostly planktonic crustaceans.