Effects of Hypoxia and Anoxia on Survival, Energy Metabolism, and Feeding of Oyster Larvae (Crassostrea virginica, Gmelin)

Abstract

The tolerance ofCrassostrea virginica larvae to anoxia increases with developmental stage and body size. Median mortality times range from 11 h for prodis soconch larvae of82 zm (shelllength) to 5 1 h for pedivel iger larvae of 3 12 zm, and 150 h forjuvenile oysters. Si multaneous 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 ofP@ down to low P@ values (2 kPa for prodissoconch larvae and 8 kPa for pediveliger andjuveniles). Therefore, total energy metabolism is sus tamed mainly by aerobic metabolism down to 2 and 4 kPa for early larval stages and juveniles, respectively. Prodissoconch larvae maintain relatively high rates of heat dissipation under anoxic conditions (34% of nor moxic rate), whereas pediveliger and juveniles lower their anoxic rates of heat dissipation to 3% of the nor moxic rate. The ability to reduce rates ofheat dissipation and thus conserve energy expenditure under anoxia ap pears to be related to the increase in anoxia tolerance with larval development. The larval differences in the re lationship between P@ and the rate of heat dissipation are also reflected in feeding rate (ingestion rate of micro spheres). Prodissoconch larvae maintain feeding activity under anoxic conditions (29% of normoxic ingestion rate), in contrast to pediveigerlarvae, which lower inges tion rates to 5% ofthe normoxic rate.

Community assembly by limited recruitment in a hypoxia-stressed soft bottom: A case study of macrobenthos in Ariake Bay

“…As the reproductive period of S. kagoshimensis overlaps with the hypoxic season, mainly July to August (Yurimoto et al 2008), hatched larvae may be killed by hypoxia (Widdows et al 1989;Wang and Widdows 1991) or avoid settlement, which is an energetically costly activity (Baker and Mann 1992). However, mass recruitment during the present study occurred during a severely hypoxic year (i.e., 2010).…”

Field and laboratory observations on the hypoxic impact on survival and distribution of short-necked clam Ruditapes philippinarum larvae in Tokyo Bay, central Japan

“…Hypoxic tolerance in the larvae oyster, C. virginica, is also lower in the early developmental stage: Lt 50 of the larvae (SLϭ167 mm) and juvenile (16 mm) in anoxic conditions at 22°C is 18 and 150 h, respectively (Widdows et al 1989). In anoxic sea water, the mortality of Theora fragilis, which is one of the dominant bivalves in hypoxic bottoms, in umbo larval and juvenile (7.2-9.5 mm) stages at 24-25°C reached 100% within 24 and 48 h, respectively (Tamai 1993, Tamai 1996.…”

“…Under anoxic and hypoxic conditions, swimming velocity (Mann & Rainer 1990) and respiration rate (Widdows et al 1989) of C. virginica larvae and growth rate in M. mercenaria larvae (Huntington & Miller 1989) declined. Thus, the decline in metabolic activity under anoxic and hypoxic conditions seems a common physiological property with bivalves.…”

“…Under low oxygen conditions for bivalve larvae, disruption in metabolic activity, retarded growth, and decreasing survival have been reported in Crassostrea virginica (Widdows et al 1989, Mann & Rainer 1990 and Mercenaria mercenaria (Huntington & Miller 1989). Both benthic and larval stages of the clam may also be affected by hypoxic or anoxic conditions, resulting in extensive stress on the growth and survival of the clam populations in eutrophicated waters in Japan.…”

Heat Shock Protein 70 Expression in Juvenile Eastern Oysters,Crassostrea virginica(Gmelin, 1791), Exposed to Anoxic Conditions

“…The metabolic rate of C. virginica (30-50 mm) under anoxia at 25°C is 75% of the normoxic rate at 25°C (Stickle et al 1989). In juvenile oyster (approximately 16 mm), it decreases to 3% of the normoxic rate at 22°C (Widdows et al 1989). As a response to metabolic arrest, protein synthesis is suppressed (Storey & Storey 2004).…”