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A Comparison of the Effectiveness of Ekman and Ponar Grabs
Author(s) -
Howmiller Richard P.
Publication year - 1971
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1971)100<560:acoteo>2.0.co;2
Subject(s) - midge , bay , ekman transport , fishery , oceanography , environmental science , geology , larva , biology , ecology , upwelling
The effectiveness of 9 × 9 inch (23 cm) Ekman and Ponar grabs was compared at 26 stations in Green Bay; on hard (N = 8) and soft (N = 18) sediments. On hard sediments the Ponar caught significantly more midge larvae (99%), but not more oligochaete worms, than the Ekman. On soft sediments the Ekman caught significantly more midges (98%) and worms (95%) than the Ponar. Differences in effectiveness of the grabs are discussed in relation to their construction. The Ponar is heavier and bites more effectively into hard substrates. The Ekman probably creates less of a shock wave and can penetrate farther into soft sediments.