Climate induced temperature effects on growth performance, fecundity and recruitment in marine fish: developing a hypothesis for cause and effect relationships in Atlantic cod (Gadus morhua) and common eelpout (Zoarces viviparus)

Abstract

Effects of global warming on animal distribution and performance become visible in many marine ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to temperature changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of invertebrate and fish species with a special focus on recent data obtained in two model species of fish. These fish species are both characterized by northern and southern distribution limits in the North Atlantic: eelpout (Zoarces viviparus), as a typical non-migrating inhabitant of the coastal zone and the cod (Gadus morhua), as a typical inhabitant of the continental shelf with a high importance for fisheries.Mathematical modelling demonstrates a clear significant correlation between climate induced temperature fluctuations and the recruitment of cod stocks. Growth performance in cod is optimal at temperatures close to 101C, regardless of the population investigated in a latitudinal cline. However, temperature specific growth rates decrease at higher latitudes. Also, fecundity is less in White Sea than in North and Baltic Sea cod or eelpout populations. These findings suggest that a cold-induced shift in energy budget occurs which is unfavorable for growth performance and fecundity. Thermal tolerance limits shift depending on latitude and are characterized by oxygen limitation at both low or high temperatures. Oxygen supply to tissues is optimized at low temperature by a shift in hemoglobin isoforms and oxygen binding properties to lower affinities and higher unloading potential. Protective stimulation of heat shock protein synthesis was not observed.According to a recent model of thermal tolerance the downward shift of tolerance limits during cold adaptation is associated with rising mitochondrial densities and, thus, aerobic capacity and performance in the cold, especially in eurythermal species. At the same time the costs of mitochondrial maintenance reflected by mitochondrial proton leakage should rise leaving a lower energy fraction for growth and reproduction. The preliminary conclusion can be drawn that warming will cause a northern shift of distribution limits for both species with a rise in growth performance and fecundity larger than expected from the Q 10 effect in the north and lower growth or even extinction of the species in the south. Such a shift may heavily affect fishing activities in the North Sea. r

Oxygen limited thermal tolerance in fish?

“…In ectothermic species, especially fish a plethora of studies have identified mechanisms of seasonal and latitudinal cold versus warm adaptation which are suitable to modulate the capacity of aerobic metabolism. As outlined above, a rise in aerobic capacity permits maintenance of cell functions in the cold (for review Guderley, 1998;Pörtner et al, , 2001. Associated processes are rising enzyme capacities (Crockett and Sidell, 1990;Guderley, 1990;Lannig et al, 2003), increased mitochondrial or capillary densities (Sisson and Sidell, 1987;Guderley and Blier, 1988;Ressel, 2001), changes in mitochondrial structure (Gaebel and Roots, 1989;St.-Pierre et al, 1998) and/or alterations in membrane composition (Miranda and Hazel, 1996;Logue et al, 2000).…”

“…Along the same lines of thought identifying mechanisms of temperature adaptation (Johnston and Bennett, 1996) and their contribution to adjusting and limiting both cold and heat tolerance are considered important in the light of global warming (e.g. Wood and MacDonald, 1997;Pörtner et al, 2001) and the associated shifts in geographical distribution and/or physiological performance of ectothermic animals .…”

In vivo MR spectroscopy and MR imaging on non-anaesthetized marine fish: techniques and first results

“…This has become important especially with respect to recent investigations of the physiological basis of temperature dependent biogeography and a cause and effect understanding of the influence of climate change on the well-being and survival of fish and invertebrate species (e.g. [13]). …”

Ecological and socioeconomic implications of a northern range expansion of black sea bass, Centropristis striata

“…In particular, temperature and the length of the growing season strongly influence growth and the timing of maturation in fishes (e.g., Pauly 1980, Conover 1990, Pörtner et al 2001, and likely vary from the edge to the center of a species' range. ).…”

“…Environmental heterogeneity across a species' range can also drive life-history variation (Brander 2010). In particular, temperature and the length of the growing season can strongly influence growth and the timing of maturation in fish (e.g., Pauly 1980, Conover 1990, Pörtner et al 2001. Spatial variations in predation pressure (e.g., Reznick et al 1990, Benard 2004, harvesting (e.g., Jorgensen et al…”