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Sampling bias of a Longhurst‐Hardy plankton recorder 1
Publication year - 1973
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1973.18.3.0500
Subject(s) - plankton , zooplankton , environmental science , sampling (signal processing) , oceanography , pellets , residence time (fluid dynamics) , leakage (economics) , zoology , biology , geology , physics , detector , geotechnical engineering , economics , macroeconomics , optics
The sampling bias due to the residence time of organisms within the net of a vertically towed Longhurst‐Hardy plankton recorder was investigated by injecting plastic pellets and preserved zooplankton into the net mouth at known times during tows. The shortest residence time was 13 sec for tow speeds of from 86 to 103 cm sec −1 ; most plankters remained in the net much longer. The injected plankton stalled within the net intermittently, causing artificial fluctuations in abundance along the recorder gauze. Differences in tow speed caused changes in stalling characteristics. Underestimates of total plankton abundance occurred, probably due to leakage through the recorder and to permanent hangups on the net.