Kristine Bonnevies hus (map)
UiO, Campus Blindern Blindernveien 31 Entr. Moltke Moes vei
Population abundance depends on production of young and survival of adults. Assessing the contribution of young production to population growth and identify the main drivers of its variability may help to identify appropriate stock management measures. What happens when several stocks, belonging to different trophic levels and habitats, as well as having different exploitation histories are sharing the same environment?
The Atlantic cod is one of the major predator in the Barents Sea estimated to consume over 5 million tonnes of fish in 2017. In a recent paper (Holt et al. 2019) we explore the diet of this species using a unique dataset encompassing 33 years of cod stomach sampling by Russian and Norwegian scientists. This time-series is the most comprehensive available cod diet dataset to date and is crucial in helping to answer ecologically important questions on what cod eat and why it matters for predator-prey and food-web dynamics in the Barents Sea ecosystem.
Many heavily fished fish stocks are dominated by young and small fish. The reason is simple: the chance to reach old age is small. If the fisheries selectively target large fish, the dominance of young and small fish becomes even larger. Such skewed age and size distributions can make the fish populations more sensitive to detrimental effects of oil spills.
Spawning migration is a prevalent phenomenon for the major fish stocks in the Barents Sea. While many of them migrate to the coast of Norway to spawn they are doing so to different areas. We have studied the Northeast Arctic haddock variability in spawning grounds to understand what drives the observed shifts over time.
In a study recently published in Ecology we find apparent competition between major zooplankton groups in a large marine ecosystem. Apparent competition is an indirect, negative interaction between two species or species groups mediated by a third species other than their prey.
High fishing pressure tends to lead to proportionally fewer old and large individuals in fish stocks. It is feared that these demographic changes make the fish stocks more sensitive to climate variability and change. Statistical analysis of long-term survey data on cod eggs throws new light on the possible mechanisms.
A recently paper published in PNAS, members of the CEES Marine Group explore potential climate effects on Calanus finmarchicus, a key zooplankton species in the North Atlantic. The paper shows how the combination of shallow mixed-layer-depth and increased wind apparently increases chlorophyll biomass in spring, and in turn C. finmarchicus biomass in summer. These findings strongly suggest bottom-up effects of food availability on zooplankton, and highlight the need to consider climate effects “beyond temperature” when projecting zooplankton dynamics under climate change.
Friday 11 December 2015, Kristina Øie Kvile has defended her PhD about the climate effects on Calanus finmarchicus dynamics with success.
Penguins are highly visible species for the public. Their life has been portrayed in many movies. Unfortunately they are also species impacted by climate change. In a recent publication a team led by Charles Bost used long-term data to relate the large-scale climatic anomalies in the Southern Hemisphere to the foraging behaviour and population dynamics of the king penguin.
Interdisciplinarity is a central focus for many funding agencies. The argument for this is that only with scientists working together that some of the major questions of today could be answered. In a recent paper, a collection of students and post-doc from the NorMER network explored the difference of perception of scientists in function of their discipline: social science or natural science.
Interdisciplinarity is often presented as the solution to answer some of the major questions of today. Master student Djuna Buizer reflected on the subject in a post.
A fundamental challenge for European Marine Science is to deliver scientific impact, global leadership and sustainable blue growth for Europe in times of overexploitation, climate change and other anthropogenic stressors. The Marie Sklodowska-Curie Innovative Training Networks MARmaED project makes important steps to answer this challenge by connecting science, policy and people, thus transcending national borders, disciplinary barriers and sectorial divides.
Spatial Ecosystem models can be useful but need to be validated with data. Our study validates for the first time the spatial version of the commonly used Ecopath with Ecosim ecosystem modelling suite. We find that spatial distribution of fish species is well predicted by the model, but fishing effort distribution is not.
In this study we assessed the chances of recovery of the Baltic Sea cod stock and conclude that it will never come back to the status it had more than three decades ago and that the economic losses associated to this new baseline amount to 120 million euros per year.
Climate warming is known to affect predator-prey relationship and phenology. Less is known about competitive relationships specifically in a nonlinear framework. In a recent study, we studied this topic on…
The Ecosystem Approach to Fisheries Management has for many years been presented as the way to go to ensure fish stock productivity and has been adopted by many governments and international organizations. But to which extent has ecosystem information in fact been included in tactical fisheries management practice?
Since Hjort’s ground-breaking work, it is admitted that the survival from the egg to the first reproduction is an essential factor affecting the dynamics of fish populations (see post). Human activities around spawning ground may have an effect on the mortality of the younger age. One of such potentially risky activity is oil exploitation which is on the increase in the northern areas.
Much of our present knowledge on the ecology and behaviour of animals is derived from longitudinal studies of individuals using long-term datasets. The collection of such datasets requires the ability to identify individuals repeatedly over time, i.e. by individual markings. Here comes the problems for Penguins.
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?
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.
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.