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Size‐dependent predation on marine fish larvae by Ctenophores, Scyphomedusae, and Planktivorous fish
Author(s) -
COWAN JAMES H.,
HOUDE EDWARD D.
Publication year - 1992
Publication title -
fisheries oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 80
eISSN - 1365-2419
pISSN - 1054-6006
DOI - 10.1111/j.1365-2419.1992.tb00030.x
Subject(s) - predation , ichthyoplankton , biology , zooplankton , bay , anchovy , larva , predatory fish , predator , goby , fishery , ecology , zoology , fish <actinopterygii> , oceanography , geology
Size‐dependent predation rates on marine fish larvae by the ctenophore Mnemiopsis leidyi , scyphomedusa Chrysaora quinquecirrha , and planktivorous fish Anchoa mitchilli were estimated via experiments in 3.2 m 3 me‐socosms. Predation rates on larvae of the goby Gobio‐soma bosci were estimated in relation to 1) length of larval prey, 2) presence or absence of alternative < 1 mm zooplankton prey, and 3) a predator‐prey interaction between the scyphomedusa and ctenophore. The consumption rate of larvae by the three predators generally declined as larval length increased. The ctenophore ate fewer (1.0 d ‐1 per predator) larvae than did the medusa (7.8 d ‐1 per predator) or bay anchovy (4.0 d ‐1 per predator), but it consumed larvae in all size classes tested (3.0–9.5 mm SL). Predation by bay anchovy and the medusa was more size‐dependent: 3.0–5.0 mm larvae were most vulnerable. Fewer larvae were eaten by the ctenophore and bay anchovy when zooplankton alternative prey was available, but predation on larvae by the medusa was not influenced by alternative zooplankton prey. Consumption rate of fish larvae by the medusa was reduced 20–25% when the ctenophore was present as its alternative prey. An encounter‐rate model was developed and its parameters estimated from the experimental results. Model simulations indicated that the relationship between larval size and vulnerability is dependent on size, swimming speed, and behavior of both predators and larvae, and that bigger or faster‐growing fish larvae are not always less vulnerable to predation.