WHAT ADAPTIVE STRATEGIES PROMOTE IMMIGRATION AND SPECIATION IN DEEP-SEA ENVIRONMENT

Deep-sea fauna is undoubtedly composed of species that are specially adapted in the course of evolution to cope with high hydrostatic pressure. Despite our knowledge on the community structure of the deep-sea benthos, modern deep-sea biologists have not yet critically posed the question: What adaptive strategies promote immigration and spéciation in deep-sea environment? This paper brings into focus the metabolic adaptive patterns that seem selectively favourable for physiological accommodation in high-pressure environment. Experimental data on the effect of pressure on the Arctic shelf amphipod Anonyx nugax suggest that pressure inhibits metabolic rate at about 150 atm which is equivalent to 1500 m that corresponds with the maximum depth of inhabitancy. Pressure tends to enhance metabolic rate at moderate hyperbaric levels (10 to 120 atm) and this stimulatory effects is somewhat pronounced at higher temperature. Another adaptive strategy of pressure-independent metabolism is seen in the vertically migrating deep-sea amphipod Eurythenes gryllus. Deep-sea decapod Parapagurus pilosimanus from 1000 m exhibit convulsive episodes at 220 ^ 10 atm, suggesting pressure-induced physiological trauma. Reduced metabolic rate in the lethargic deep-sea animals implies low energy input and possibly this adaptive strategy is a catalytic force in the successful colonization of high pressure and low temperature biosphere of pronounced food deficiency. © 1979 Taylor & Francis Group, LLC.