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Effects of climate induced temperature change on marine coastal fishes.

Deliverables

The NMR spectra processing user program allows the automatic processing and analysing of large data piles. After Fourier transformation of the NMR spectra, signals can be identified automatically. The analysing includes signal peak picking, line width determination and an integration routine by a fitting routine. The results will be stored in chronological order in text files that can be imported in standard software like Excel for further calculations. Results were in excellent correlation to manual data manipulation, allowing more than a five times faster data processing.
The combined results of physiological, ecological and modelling data support and widen the basis for a comprehensive hypothesis explaining the limiting effects of temperature change on marine coastal fishes. Thermal tolerance is oxygen limited and the mismatch between oxygen demand and oxygen supply to tissues during temperature increase is a result of circulatory malfunction. At high temperatures, excessive oxygen demand causes decreasing oxygen levels in the body fluids, whereas at low temperatures the aerobic capacity of mitochondria may become limiting for ventilation and circulation. This concept would explain tradeoffs within energy budgets with the respective consequences for temperature dependent changes in growth, fecundity and recruitment, ecological key processes that determine population structure and dynamics.
The pH-electrode is a modification of a previous model (Radiometer) for the measurement of blood samples. It is especially designed for the measurement of small biological samples under temperature control. This is a prerequisite for the measurement of intracellular pH according to the homogenate method (Pörtner et al., 1990). Existing miniature pH electrodes are either not precise enough due to the small surface and/or temperature control is difficult and often impossible especially a very low temperatures. Due to the capillary design of the new pH-electrode the sensitive surface is sufficiently large and the special design allows temperature control between 0 degrees and 40 degrees.
In general, growth and fecundity of cod and eelpout increase with decreasing latitude. For both model species, we found on the basis of historical, field and experimental growth data, a significant influence of the temperature regime on growth and reproduction. North Sea and Barents Sea represent the upper and lower temperature extremes of the thermal tolerance window of cod, evidenced by the thermal tolerance and recruitment studies. For eelpout as well as for cod growth performance and fecundity decrease significantly at higher latitudes. Model calculations applied to determine the optimal temperature in cod from different climatic regimes revealed also highest growth rates of Gadus morhua from the North Sea followed by the animals from the Norwegian coast and the Arctic region. Warming will likely lead to a rise in growth performance and fecundity for northern populations and to a decrease in populations living at the southern border of their distribution.
Fishery data published by the FAO agency was analysed by a multivariate statistical approach for the two fishing areas spanning from 51 degrees 00' E to 42 degrees 00' W (Eastern Atlantic), and from 42 degrees 00' to 80 degrees 00' W (Western Atlantic). The time series of fishery data concerning the same species in the two areas were correlated among each other as well as with the corresponding sea surface temperatures. In the studied time span (1984-1996), the trend of the time series is: - Similar in the two areas, namely increasing in the eastern and decreasing in the western area; - Not significantly correlated with the yearly averaged sea surface temperatures. It is difficult to attribute such results exclusively to human activity, since globalisation of economical and industrial activities would tend to homogenize their effect over the European and the American sides of North Atlantic. This emphasizes the importance of the environmental and ecological contributions. The results and the underlying analytical approach have been only presented and critically discussed, up to now, in scientific meetings.
The device developed for precise temperature control (+/-0.1 degrees Celsius) inside wells of 96-well format microtiterplate within very broad temperature range from 0 degrees Celsius to 60 degrees Celsius. A new approach to temperature control in microtiterplate allows measuring temperature dependence of enzyme kinetic as well as thermodynamic parameters. 96-well format allows increasing the rate and quality of data collection in 100 times. All the microtiterplate readers with temperature control feature that are available on market can control temperature only above room temperature (>25 degrees Celsius) this is an obvious disadvantage for people working with enzyme kinetics and thermodynamics, especially in cases where these parameters have to be determined at ecologically relevant temperatures and in huge amount. The price of the device is relatively low, however in order to use it the microtiterplate reader has to be slightly redesigned. The device is very simple in operation. This device has big potential for application in enzyme research fields; especially it is important for biotechnology, biomedical and pharmaceutical sciences.
Acclimation at 12 degrees Celsius is by far the most favourable growth condition for Gadus morhua in a stable and controlled (lab) environment. Moving off the optimum towards the high-temperature side induces a more marked decrease in growth than moving towards the low-temperature side. Statistical analysis of data indicates that the acclimation temperature correlates with growth more significantly than the haemoglobin genotype. A correlation study over environmental parameters (NAO index and surface temperature) and recruitment data for Atlantic cod in the region surrounding the Kola peninsula (Barents sea) and in the North Sea indicated: i) two independent effects on cod recruitment for the Kola region, pointing to the existence of at least two different mechanisms of comparable importance by which temperature may affect cod populations; ii) only one major interaction mechanism in the North Sea. Moreover, cod recruitment and NAO spaces did not show any significant canonical correlation. Thus, temperature is the climate "observable" directly acting on (i.e. sensed by) cod populations. As for the North Sea, a parallel analysis of haddock and herring recruitment produced very similar results.