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Effects Of Hypoxia On Predator-Prey Dynamics Of The Blue Crab Callinectes Sapidus And The Baltic Clam Macoma Balthica In Chesapeake Bay, Rochelle D. Seitz, Ls Marshall, Ah Hines, Kl Clark

VIMS Articles

In general, hypoxia (< 2 mg O-2 l(-1)) is detrimental to marine food webs because of faunal declines associated with persistent, severely low oxygen. However, transfer of benthic production to higher trophic levels could be facilitated under hypoxia if infauna migrate to shallower burial depths, increasing their availability to predators. A series of outdoor mesocosm and laboratory experiments were conducted in 3 years (1999 to 200 1) to quantify the effects of hypoxia upon (1) predation by the blue crab Callinectes sapidus on the Baltic clam Macoma balthica, a biomass dominant in Chesapeake Bay, and (2) burial depth and survival of M, balthica. For the predation experiments, 12 M. balthica were transplanted into replicate 1200 1 mesocosms at 48 clams m(-2) under normoxia (>8 mg O-2 l(-1)) or low dissolved oxygen (low DO; l(-1)) either without or with a male blue crab that was allowed 2 d to feed upon the clams. Predation-induced proportional mortality of clams was significantly lower under low DO than under normoxia in all 3 years. Thus, under short-term hypoxia, both crab feeding efficiency and trophic transfer from M balthica to blue crabs were reduced. Changes in clam burial depth due to oxygen levels was determined by establishing normoxic and low DO treatments in replicate 208 1 aquaria in 2 years. Burial depth after exposure …