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Full-Text Articles in Aquaculture and Fisheries

Effects Of Hypoxia And Anoxia On Survival, Energy Metabolism, And Feeding Of Oyster Larvae (Crassostrea Virginica, Gmelin), J Widdows, Rie Newell, Roger L. Mann Aug 1989

Effects Of Hypoxia And Anoxia On Survival, Energy Metabolism, And Feeding Of Oyster Larvae (Crassostrea Virginica, Gmelin), J Widdows, Rie Newell, Roger L. Mann

VIMS Articles

The tolerance of Crassostrea virginica larvae to anoxia increases with developmental stage and body size. Median mortality times range from 11 h for prodissoconch larvae of 82 micro m (shell length) to 51 h for pediveliger larvae of 3 12 micro m, and 150 h for juvenile oysters. Simultaneous calorimetry and respirometry showed that in response to declining oxygen tension (P02), the rates of heat dissipation and oxygen uptake by oyster larvae are maintained independent of PO2 down to low Pc values (2 kPa for prodissoconch larvae and 8 kPa for pediveliger and juveniles). Therefore, total energy metabolism is sustained …


Biological Control Of Crab Predation On Hard Clams Mercenaria Mercenaria (Linnaeus, 1758) By The Toadfish Opsanus Tau (Linnaeus) In Tray Cultures, Robert Bisker, Michael Castagna Jan 1989

Biological Control Of Crab Predation On Hard Clams Mercenaria Mercenaria (Linnaeus, 1758) By The Toadfish Opsanus Tau (Linnaeus) In Tray Cultures, Robert Bisker, Michael Castagna

VIMS Articles

Oyster toadfish Opsanus tau (Linne) were tested as biological controls of crab predation on juvenile hard clams Mercenaria mercenaria (Linne) in trays with crushed stone aggregate. Clam survival after 34 weeks was 69.5% in the presence of toadfish and 2.3% in trays without toadfish. Toadfish reduced the total number of crabs (mud crabs and blue crabs). Crabs in trays with toadfish present had smaller carapace widths.


Predation By The Oyster Toadfish Opsanus Tau (Linnaeus) On Blue Crabs And Mud Crabs, Predators Of The Hard Clam Mercenaria Mercenaria (Linnaeus, 1758), Robert Bisker, Mary Gibbons, Michael Castagna Jan 1989

Predation By The Oyster Toadfish Opsanus Tau (Linnaeus) On Blue Crabs And Mud Crabs, Predators Of The Hard Clam Mercenaria Mercenaria (Linnaeus, 1758), Robert Bisker, Mary Gibbons, Michael Castagna

VIMS Articles

The oyster toadfish, Opsanus tau (Linne), reduces predation by xanthid and portunid crabs on juvenile hard clams, Mercenaria mercenaria (Linne), in field cultures. This study examined the influence of size and species on the predator-prey relationship between toadfish and crabs. The mud crabs Eurypanopeus depressus (Smith), Neopanope sayi (Smith), and Panopeus herbstii Milne Edwards of 5-40 mm carapace width and blue crabs Callinectes sapidus Rathbun of 77-105 mm carapace width were offered to toadfish of 70-322 mm total length. Toadfish predation rates on mud crabs were higher with increasing toadfish size and lower with increasing crab size. Toadfish injured or …