Effect of ocean alkalinity enhancement on early life history stages of herring in natural mesocosms (KOSMOS)
The present experiment aims to test the effects of ocean alkalinity enhancement (OAE) as a proposed CO2-removal-method on the survival, growth and development of herring larvae. The effect of OAE is an emerging field, and this experiment will be (to our knowledge) the first study to look at the effect of OAE on fish larvae. Based on the expected OAE-induced changes in carbonate chemistry and increase in pH, the direct effects will be minimal, if at all detectable. We expect more effects on the fish larvae being indirect, meaning mediated by the food web: from OAE-induced changes in the phytoplankton such as diatoms, coccolithophores and dinoflagellates their predators, the zooplankton (such as copepods) could be affected, which will in the following serve as food for the herring larvae.
Eggs and larvae from Norwegian spring-spawning herring (Clupea harengus) will be incubated in the laboratory at the University of Bergen (separate animal welfare application). Alternatively, eggs may be obtained from strip spawning and then rear in onshore mesocosms at the Espegrend Research Station. One hundred herring larvae (~10 mm, either from UiB lab or onshore mesocosms) will be introduced in each of ten KOSMOS mesocosms (40 m3 – offshore mesocosms). Herring larvae will live and feed on the plankton community that developed under one of two experimental treatments: increased gradient of alkalinity (0, 600, 1200, 1800, 2400 increased in total alkalinity) based on silicate or calcium carbonate minerals). Survival, growth and development will be monitored from regular samples in the KOSMOS mesocosms. Larvae will be will be collected by plankton nets, anesthetized and photographed in the lab, then euthanized and transferred immediately to a -80°C freezer for storage for later biochemical analysis. The number of experimental animals (total of 1000 larvae) has been carefully reduced to the minimum needed to observe an effect on the planktonic community (via predation).
This will be a cooperation between the GEOMAR Hemholtz Center for Ocean Research (Dr. Michael Sswat, Dr. Silvan Goldenberg), the University of Bergen (Prof. Arild Folkvord), the University of Hamburg (Gregor Boerner) and the University of Agder (Ass Prof Mart Moyano). Researchers from the team have previously worked together in other mesocosm experiments. Previous experiments have been investigating the effect of ocean acidification (opposite effect on pH in comparison to OAE) on herring larvae of local (Bergen, Norway & Kristineberg, Sweden) herring populations in the lab (direct effect) and in the KOSMOS (direct effect + indirect effect via food web). In the lab, negative effects of extreme ocean acidification (>1800 µatm pCO2) have been measured on growth and survival, but not on alteration of swimming or feeding behavior. In the KOSMOS, under realistic end of the century ocean acidification scenarios, no negative effects were found but positive effects from changes in the food web. The target species in Atlantic herring and thus no replacement is possible.
Eggs and larvae from Norwegian spring-spawning herring (Clupea harengus) will be incubated in the laboratory at the University of Bergen (separate animal welfare application). Alternatively, eggs may be obtained from strip spawning and then rear in onshore mesocosms at the Espegrend Research Station. One hundred herring larvae (~10 mm, either from UiB lab or onshore mesocosms) will be introduced in each of ten KOSMOS mesocosms (40 m3 – offshore mesocosms). Herring larvae will live and feed on the plankton community that developed under one of two experimental treatments: increased gradient of alkalinity (0, 600, 1200, 1800, 2400 increased in total alkalinity) based on silicate or calcium carbonate minerals). Survival, growth and development will be monitored from regular samples in the KOSMOS mesocosms. Larvae will be will be collected by plankton nets, anesthetized and photographed in the lab, then euthanized and transferred immediately to a -80°C freezer for storage for later biochemical analysis. The number of experimental animals (total of 1000 larvae) has been carefully reduced to the minimum needed to observe an effect on the planktonic community (via predation).
This will be a cooperation between the GEOMAR Hemholtz Center for Ocean Research (Dr. Michael Sswat, Dr. Silvan Goldenberg), the University of Bergen (Prof. Arild Folkvord), the University of Hamburg (Gregor Boerner) and the University of Agder (Ass Prof Mart Moyano). Researchers from the team have previously worked together in other mesocosm experiments. Previous experiments have been investigating the effect of ocean acidification (opposite effect on pH in comparison to OAE) on herring larvae of local (Bergen, Norway & Kristineberg, Sweden) herring populations in the lab (direct effect) and in the KOSMOS (direct effect + indirect effect via food web). In the lab, negative effects of extreme ocean acidification (>1800 µatm pCO2) have been measured on growth and survival, but not on alteration of swimming or feeding behavior. In the KOSMOS, under realistic end of the century ocean acidification scenarios, no negative effects were found but positive effects from changes in the food web. The target species in Atlantic herring and thus no replacement is possible.