Functional significance of a partial-emersion response in the intertidal prawn Palaemon elegans (Crustacea: Palaemonidae) during environmental hypoxia

Abstract

During exposure to severe hypoxia (<20 Torr [2.7 x 103 Pal) under both laboratory and field conhtions, prawns Palaemon elegans Rathke frequently exhibited a parbal-emersion response dunng which they moved into shallow water and became quiescent, usually lying on their sides at the water's edge. The Poz at which this behavioural response occurred appeared to be dependent on temperature; at higher temperatures the prawns exhibited this response at higher oxygen tensions. When exposed to anoxic conditions in the laboratory, P. elegans sometimes left the water and emerged onto boulders. Investigations of the physiological advantages of the partial-emersion response demonstrated that the total oxygen content of the blood was significantly higher and the concentration of Llactate lower than that of either fully immersed or totally emersed prawns It appears, therefore, that P. elegans is able to exploit the higher oxygen tensions at the air/water interface and can meet most of its metabolic demands via aerobic metabolism. Although prawns which emerge completely from the water when exposed to anoxia may be able to utilize air as a source of oxygen, they are faced with problems of acid-base disturbance In the blood due to the difficulties of CO2 excretion. In these prawns, the total CO2 content of the blood was significantly higher and the pH lower than that of partially-emersed prawns. By remaining in contact with the water, partially-emersed prawns gain an important respiratory advantage and are able to reduce the problems both of acid-base disturbance and of desiccation during total emersion.

Does feeding limit cardiovascular modulation in the Dungeness crabCancer magisterduring hypoxia?

“…In some instances behavioural regulation may be employed by crustaceans as a means of avoiding hypoxia, thus negating the use of physiologically costly processes (Taylor and Spicer, 1988). For example, in the laboratory, postprandial Dungeness crabs will select higher oxygen regimes to digest food (Bernatis and McGaw, 2004).…”

Catch me in winter! Seasonal variation in air temperature severely enhances physiological stress and mortality of species subjected to sorting operations and discarded during annual fishing activities

“…Bridges & Brand, 1981;DeFur, 1988;Taylor & Spicer, 1988;Stillman & Somero, 1996) as well as for subtidal species that could be forced to emersion as a consequence of commercial fishing activities (Schmitt & Uglow, 1997;Morris & Oliver, 1999a, b;Bergmann et al, 2001b;Danford et al, 2002). From this literature, it emerges that during sorting and shipping procedures benthic crustaceans, which inhabit stable environments and are virtually unable to cope with emersion, undergo a series of circulatory, respiratory, and metabolic impairments.…”

Effects of short-term hypoxia on metabolism and haemocyanin oxygen transport in the prawns Palaemon adspersus and Palaemonetes varians

“…In this way, the prawns are able to ventilate their gills with water that can be expected to have a higher oxygen tension than water deeper in the water column. Hagerman & Uglow (1984) also noted that during hypoxia P. varians jumped out of the water and for a short time adhered to plants etc . Taylor & Spicer (1988) noted also that during severe hypoxia, Palaemon elegans exhibited a partial emersion response, remaining quiescent at the air water interface.…”