Researcher, PhD
Anders F. Opdal

The evolution and ecology of life-history

For the past few years, my main focus has been circling around a couple of questions regarding changes in life history events. What drives change, and how to disentangle the ecological (demography) and evolutionary effects. The work essentially runs along two dimensions, space and time - both involving cod (of course). In the first (space), I try to disentangle the drivers for long term change in spawning ground location in Northeast arctic cod, while in the other (time) I look closer into the drivers for change in spawning time (phenology). The latter initiative became an RCN funded project in 2019- A green-blue link made browner: how terrestrial climate change affects marine ecology. See here for the project's own webpage.

Disentangling drivers of spawning migration

Human harvest is inherently selective and if sufficiently intense, has a direct and observable effect on the presence of phenotypic traits in a population; including body size, sex, colour, attributes etc. Although rarely quantified, intense harvest is also likely to be selective on genotypes within contemporary timescales - a process known as human induced evolution. See here for TEG's earlier research on this topic. However, seperating between demographic and evolutionary effects has turned out to be challenging

But there is hope. The Northeast Arctic cod may just be the ideal candidate for for such an investigation, as data on fishing pressure, demography and spawning locations have been meticously collected, either for scientific or commercial purposes, for up to 150 years.

Based on these data and in conjunction with state dependent optimization models, I have, together with several co-authors, presented results suggesting that intense harvest on not only alters age structure in the population, but may also lead to evolutionary change in life history strategies such as age at maturation and spawning migration.

The picture is complex, and multiple drivers are at play - many of which are still poorly understood.

Linking terrestrial greening to coastal ecology

During the last century or so, Europe, and particularly the Fennoscandian countries (Norway, Sweden and Finland) has seen a tremendous increase in forrest cover - aka greening. Today, Sweden has five times more forest than in the early 1900s, and Norway has double.

A concurrent trend, has been the increase in colour dissolved organic matter (CDOM) in freshawer lakes and rivers, observable as browner water. A less studied aspect of terrestrial greening is the effect on coastal ecosystems, to which all this brown freshwater drains. My collegue Dag L. Aksnes was early to point out the effect and coined it coastal water darkening .

In 2019, TEG, together with the AKVA group and Department of Geosiences (both at the University of Oslo), recieved funding from the RCN to develop the field further. The project A green-blue link made browner: how terrestrial climate change affects marine ecology aims to recontruct the historical (and future) CDOM flux from land to coast, investigate the ecological effects of coastal systems, and particularly estimate the influence on the timing of life-history events (phenology) from phytoplankton to fish. Please visit the project website here for more information