Browsing Bergen Open Research Archive by Author "Opdal, Anders Frugård"
Now showing items 1-11 of 11
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Caught in broad daylight: Topographic constraints of zooplankton depth distributions
Aarflot, Johanna Myrseth; Aksnes, Dag Lorents; Opdal, Anders Frugård; Skjoldal, Hein Rune; Fiksen, Øyvind (Peer reviewed; Journal article, 2019-05)For visual predators, sufficient light is critical for prey detection and capture. Because light decays exponentially with depth in aquatic systems, vertical movement has become a widespread strategy among zooplankton for ... -
Centennial decline in North Sea water clarity causes strong delay in phytoplankton bloom timing
Opdal, Anders Frugård; Lindemann, Christian; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2019-08-23)With climate warming, a widespread expectation is that events in spring, such as flowering, bird migrations, and insect bursts, will occur earlier because of increasing temperature. At high latitudes, increased ocean ... -
Dying from the lesser of three evils: facilitation and non-consumptive effects emerge in a model with multiple predators
Fouzai, Nadia; Opdal, Anders Frugård; Jørgensen, Christian; Fiksen, Øyvind (Peer reviewed; Journal article, 2019)Prey modify their behaviour to avoid predation, but dilemmas arise when predators vary in hunting style. Behaviours that successfully evade one predator sometimes facilitate exposure to another predator, forcing the prey ... -
Dynamics of spawning migrations in Northeast Arctic cod
Opdal, Anders Frugård (Doctoral thesis, 2010-12-10)The Northeast Arctic (NA) cod is known to undertake long southbound spawning migrations from their feeding grounds in the Barents Sea, to various spawning grounds along the Norwegian coast. Hence it’s native Norwegian name ... -
Effects of temperature and food availability on larval cod survival: A model for behaviour in vertical gradients
Fouzai, Nadia; Opdal, Anders Frugård; Jørgensen, Christian; Fiksen, Øyvind (Peer reviewed; Journal article, 2015-06-08)Recruitment success in living marine resources is variable due to high survival variability of early life stages. Improving our understanding of how environmental and ecological factors mechanistically interact and influence ... -
Herding mesopelagic fish by light
Kaartvedt, Stein; Røstad, Anders; Opdal, Anders Frugård; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2019)To assess organisms forming mesopelagic scattering layers in the Red Sea, we took advantage of their reactions to light. We used a remotely operated vehicle (ROV) equipped with LED lamps for herding the acoustic targets ... -
Large annual variation in the amount of skipped spawning for female Northeast Arctic haddock Melanogrammus aeglefinus
Skjæraasen, Jon Egil; Korsbrekke, Knut; Dingsør, Gjert Endre; Langangen, Øystein; Opdal, Anders Frugård; Jørgensen, Christian (Journal article; Peer reviewed, 2020-10)Although the phenomenon of skipped spawning has been described in numerous fishes, time-series are scarce. We used the presence of post-ovulatory follicles in histological gonad slides from females not developing oocytes ... -
Long-term change in a behavioural trait: truncated spawning distribution and demography in Northeast Arctic cod
Opdal, Anders Frugård; Jørgensen, Christian (Peer reviewed; Journal article, 2015-04)Harvesting may be a potent driver of demographic change and contemporary evolution, which both may have great impacts on animal populations. Research has focused on changes in phenotypic traits that are easily quantifiable ... -
Relationships between spawning ground identity, Latitude and early life thermal exposure in Northeast Arctic Cod
Opdal, Anders Frugård; Vikebø, Frode B.; Fiksen, Øyvind (Peer reviewed; Journal article, 2008)from its feeding grounds in the Barents Sea to various spawning banks along the Norwegian coast. Prior to the 1990s these banks were located on a wide latitudinal range from Finnmark (~71º N) to Møre (~63º N), or even to ... -
Response: Demography affects spawning location in Northeast Arctic cod, but what affects demography?
Opdal, Anders Frugård; Jørgensen, Christian (Journal article, 2015-06-19) -
Unclear associations between small pelagic fish and jellyfish in several major marine ecosystems
Opdal, Anders Frugård; Brodeur, Richard D.; Cieciel, Kristin; Daskalov, Georgi; Mihneva, Vesselina; Ruzicka, James J; Verheye, Hans M.; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2019-02-28)During the last 20 years, a series of studies has suggested trends of increasing jellyfish (Cnidaria and Ctenophora) biomass in several major ecosystems worldwide. Some of these systems have been heavily fished, causing a ...