Influence of environmental salinity on oxygen consumption and ammonia excretion of the arctic under-ice amphipodOnisimus glacialis

Abstract

Abstract. Changes in salinity affect the metabolic rate of the sympagic amphipod Onisimus glacialis collected from the Barents Sea in 1986 and 1988. When transferred from 35 to 5 ppt S, oxygen consumption and ammonia excretion both increase three-fold during the first 5 h of exposure, and they remain high throughout the rest of the experimental period (26 h). During 24-h acclimation to various salinities (5 to 45 ppt), the amphipods exhibit a respiratory and excretory response to hyper-and hypoosmotic stress; however, a rather constant O:N atomic ratio (around 15) was obtained at the experimental salinities, indicating protein/lipids as metabolic substrate. Both rates of oxygen consumption and ammonia excretion increased with an increasing osmotic difference (0 to 650 mOsm) between the haemolymph and the environmental medium, indicating higher energy requirements for osmotic and ionic regulation at low salinities. In amphipods abruptly transferred from 35 to 5 ppt, a minor decrease of the haemolymph sodium concentrations together with an increased ammonia excretion output indicate a counter-ion regulation of NH~ and Na + during hyposmotic stress.

Molecular cloning and expression of hepatopancreas glutamine synthetase in the Pacific white shrimp, Litopenaeus vannamei, induced by acute hypo-osmotic stress

“…Marine animals increase their oxygen uptake, maintain a high respiratory rate, and increase the protein catabolism rate by maintaining energy consumption in response to environmental stresses (salinity, hypoxia, pathogenic bacteria, etc.) (Aarset and Aunaas, 1990;Diaz et al, 2001;Hagerman et al, 1990;Racotta et al, 2002). GS can help in ammonia detoxification by catalyzing ammonia, which is the product of protein catabolism to form glutamine.…”

Bioenergetic effects of sodium sulfate on the freshwater crustacean, Ceriodaphnia dubia

“…While a wealth of literature exists on the physiological effects observed in organisms exposed to changes in salinity when sodium and chloride are the dominant ions, i.e., seawater (e.g., Aarset and Aunaas 1990;Arné r and Koivisto 1993;Cowgill and Milazzo 1990;Guerin and Stickle 1992;Richmond and Woodin 1999), only recently has toxicity of effluents dominated by other ''major ions'' (particularly sodium and sulfate) in freshwater systems received increasing attention (Goodfellow et al 2000). Common sources of effluents with elevated total dissolved solids (TDS), which in freshwater is essentially the sum of the concentrations of all common ions, include reverse osmosis systems, pH modifications of waste water, agricultural runoff, gas and oil production, and coal or metal mining operations (Goodfellow et al 2000).…”

Oxygen consumption of the aquatic leaf beetles Macroplea mutica and Macroplea appendiculata is low and not influenced by salinity

“…However, it is known from other aquatic organisms that alterations in salinity constitute a type of environmental stress that influences the metabolic rate of animals. For example, in crustacean species in which a distinct pattern of oxygen consumption is observed, it would typically increase when animals were transferred to an unusually low salinity (Dehnel, 1960; Simmons & Knight, 1975; Nelson et al , 1977; von Oertzen, 1985; Dalla Via, 1986; Aarset & Aunaas, 1990; Roast et al , 1999; McAllen & Taylor, 2001; Lapucki & Normant, 2008). This increased consumption is interpreted as an increased energy demand for osmoregulation, and is supported by the observation of minimal oxygen consumption at the point of isotonicity (salinity 22) in Crangon vulgaris (Hagerman, 1970).…”