Extreme sensitivity of biological function to temperature in Antarctic marine species

Abstract

Summary1. Biological capacities to respond to changing environments dictate success or failure of populations and species over time. The major environmental feature in this context is often temperature, and organisms across the planet vary widely in their capacity to cope with temperature variation. With very few exceptions, Antarctic marine species are more sensitive to temperature variation than marine groups elsewhere, having survivable temperature envelopes between 5 °C and 12 °C above the minimum sea temperature of −2 °C. 2. Our findings show that in biological functions important to long-term survival these animals are even more tightly constrained. The Antarctic bivalve mollusc Laternula elliptica and limpet Nacella concinna both survive a few days in experiments at 9-10 °C, but suffer 50% failure in essential biological activities at 2-3 °C and complete loss at 5 °C. The Antarctic scallop Adamussium colbecki is even more sensitive, and loses the ability to swim as temperature approaches 2 °C. 3. These failures of activity are caused by a loss of aerobic capacity, and the animals investigated are so sensitive that a 2 °C rise in sea temperature could cause population or species removal from the Southern Ocean.

Plasticity in shell morphology and growth among deep-sea protobranch bivalves of the genus Yoldiella (Yoldiidae) from contrasting Southern Ocean regions

“…These turbulent and complex oceanographic processes increase heterogeneity in a system that may otherwise be considered highly stenothermal and stable (Barnes et al, 2006;Clarke et al, 2009). Small changes in temperature are known to cause drastic changes in metabolic rates of Antarctic benthic invertebrates in shallow water (Peck et al, 2002;Peck et al, 2004) but to date there is no published work on metabolic rates of deep-sea Antarctic invertebrates.…”

“…Low temperatures increase the cost of calcification and reduce metabolic rates (Peck et al, 2004), and increasing temperatures have been shown to directly increase growth rates of Southern Ocean bivalves (Nolan and Clarke, 1993;Brey et al, 2011). The effect of temperature can also be observed with a decrease in shell thickness with latitude in buccinid gastropods and echinoids while increasing shell thickness in the bivalve genus Laternula (Watson et al, 2012), where mechanical damage and associated shell repair increases calcification (Harper et al, 2012) at the cost of increased metabolic activity (Phillip et al, 2011).…”

“…Key adaptations are a gill structure exclusively used for respiration, modified palps for feeding, and long digestive systems to process huge quantities of fine sediment in areas of impoverished food supply (Zardus, 2002;Allen, 2008). In the Antarctic, protobranch bivalves are well represented, although the ecology of the deep-water species remain unknown and only the common shallow water Yoldia eightsii has been studied in any detail (Davenport, 1988;Peck and Bullough, 1993;Peck et al, 2004) Phenotypic plasticity is a common trait in marine intertidal molluscs (e.g. Vermeij, 1973;Nolan, 1991;Trussell, 2000;Bayne, 2004;Sousa et al, 2007) where adapting to different environmental conditions may increase their chances of survival and successful dispersal.…”

Lack of an HSP70 heat shock response in two Antarctic marine invertebrates

“…2°C (Peck 2002), they start to lose critical biological functions at temperatures 2-3°C higher than current summer maxima (Peck et al, 2004). The question posed is how do we monitor the effects of heat stress in such organisms and are heat shock proteins the most appropriate biomarker for environmental stress in the Antarctic?…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…Advection from the sub-Arctic into the Arctic in both the Pacific and Atlantic sectors provides potential pathways of dispersal for planktonic eggs and larvae and facilitates the expansion of fish populations into a warming Arctic (Hollowed et al, 2013). The advection of warmer waters into the Arctic, combined with local warming, suggests that boreal fish species may increasingly outcompete cold-adapted, stenothermic (requiring a narrow range of ambient temperatures) species (Peck et al, 2004;Laurel et al, 2016aLaurel et al, , 2016b, resulting in a ''borealization" of the Arctic (Fossheim et al, 2015). Significant changes in the advection of zooplankton or ichthyoplankton under climate warming would cause changes in the populations of fish.…”