Some while ago a student asked us if we were collecting data in the marine ecological group at CEES. We were forced to acknowledge that we were not. From this follows a real cri de coeur: “but we are only scavengers!” Are we really? If we are, is it all bad?
Marine Science blog - Page 3
Phytoplankton biomass is controlled by a combination of “bottom-up” factors such as temperature, light and nutrients and “top-down” factors, in particular zooplankton predation. In a recent study we analysed large-scale data on ocean chlorophyll, copepod abundance and temperature in order to assess the general importance of bottom-up and top-down factors in controlling phytoplankton biomass.
In 2005 Stenseth and colleagues wrote a tribune in the Theme section of MEPS ‘Bridging the gap between aquatic and terrestrial ecology’ arguing on the mutual benefit of uniting ecologists to give birth to new science and understanding. In December 2014 we got funded a big project by the Norwegian Research Council to do just so in Norway.
Increased sea temperature due to climate change can influence the distribution, abundance and seasonal timing of zooplankton. Changing zooplankton dynamics might in turn impact the higher trophic levels, such as fish and seabirds, feeding on these animals. In a recent paper, we show that temperature variation in the Atlantic waters of the Norwegian Sea and Barents Sea might have stronger effects on the abundance of the younger than older development stages of Calanus finmarchicus, and that these stages might appear earlier in spring during warm years.
Climate change is thought to change many aspects of the marine life. Among others, one can mention changes in species distribution (immigration of species; new species coming to northern areas), the rate of development (warmer the temperature, the faster is the development), and change in the timing of the reproduction. The latter has recently caught a lot of attention around a nearly 50 years old hypothesis of the British fisheries biologist David Cushing.
Climate change, and especially alteration in sea temperature, is expected to have major effects on the distribution and abundance of marine fish. This is in particular the case in northern high-latitude marine ecosystems, where IPCC expects global warming to be especially pronounced.
Short supplies of adequate nesting sites and food resources are often associated in discussions of the ultimate factors controlling seabird population size, distribution and breeding success. Shift of prey distribution may affect the interaction between seabirds breeding at the same site.
Statistical analyses of long-term monitoring data reveal an inverse relationship between the biomasses of zooplankton and plankton-eating fish, but only in the northern and central parts of the Barents Sea. In the southwestern Barents Sea, so such relationship is found.
Understanding the interaction between species is particularly actual in marine systems where ecosystem approach of management is desirable. This is particularly the case in high latitude systems such as the Barents Sea where climate change effect is supposed to be the strongest.
Mortality of pelagic eggs and larvae of marine fish is often assumed to be constant both in space and time due to lacking information. This may, however, be a gross oversimplification, as early life stages are likely to experience large variations in mortality both in time and space.
Understanding the drivers that determine the productivity of marine ecosystems is an important issue. Climate and exploitation interact in their effects, such that climate alterations may cause failure in a fishery management scheme while fisheries may disrupt the ability of a population to withstand, or adjust to, climate changes.