Artsfordeling og bestandsstørrelser for de ulike artene av leppefisk i de undersøkte områdene

Sammensetningen av leppefiskarter er signifikant forskjellige mellom alle lokalitetene som ble undersøkt, også mellom lokaliteter som ligger nær hverandre. De dominerende artene var grønngylt og bergnebb alle steder foruten Smøla som bare hadde bergnebb i fangstene. Grønngylt hadde større gjenfangstfrekvens enn bergnebb på alle lokalitetene dette ble målt foruten de to Tysnes – lokalitetene. Der var det ingen signifikante forskjeller mellom disse to artene

Regulation of gene expression is associated with tolerance of the Arctic copepod Calanus glacialis to CO2-acidified sea water

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Program rensefisk: Kunstig lys og rensefisk - Sluttrapport FHF prosjekt 901146

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Effect of Sub-Lethal Exposure to Ultraviolet Radiation on the Escape Performance of Atlantic Cod Larvae (Gadus morhua)

The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to depletion of the ozone layer. Several studies have reported that UV radiation reduces survival of fish larvae. However, indirect and sub-lethal impacts of UV radiation on fish behavior have been given little consideration. We observed the escape performance of larval cod (24 dph, SL: 7.6±0.2 mm; 29 dph, SL: 8.2±0.3 mm) that had been exposed to sub-lethal levels of UV radiation vs. unexposed controls. Two predators were used (in separate experiments): two-spotted goby (Gobiusculus flavescens; a suction predator) and lion's mane jellyfish (Cyanea capillata; a “passive" ambush predator). Ten cod larvae were observed in the presence of a predator for 20 minutes using a digital video camera. Trials were replicated 4 times for goby and 5 times for jellyfish. Escape rate (total number of escapes/total number of attacks ×100), escape distance and the number of larvae remaining at the end of the experiment were measured. In the experiment with gobies, in the UV-treated larvae, both escape rate and escape distance (36%, 38±7.5 mm respectively) were significantly lower than those of control larvae (75%, 69±4.7 mm respectively). There was a significant difference in survival as well (UV: 35%, Control: 63%). No apparent escape response was observed, and survival rate was not significantly different, between treatments (UV: 66%, Control: 74%) in the experiment with jellyfish. We conclude that the effect and impact of exposure to sub-lethal levels of UV radiation on the escape performance of cod larvae depends on the type of predator. Our results also suggest that prediction of UV impacts on fish larvae based only on direct effects are underestimations

Grazing Rates of Calanus finmarchicus on Thalassiosira weissflogii Cultured under Different Levels of Ultraviolet Radiation

UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR): photosynthetically active radiation (PAR) only (4 kJ-m−2/day), and PAR supplemented with UVR radiation at two intensities (24 kJ-m−2/day and 48 kJ-m−2/day). There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66%) higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem

Alder og vekst hos de ulike artene av leppefisk i utbredelsesområdet

De ulike leppefiskartene har forskjellige livshistorier. Bergnebb vokser seint, men ganske jevnt gjennom livet. De vil ha en alder på 4-5 år før de når fangbar størrelse på 11 cm som var instestørrelsen i 2012. Grønngylt vokser raskt til å begynne med, men veksten flater ut senere i livet. Grønngylt har stor variasjon i vekst mellom individer, og en kan finne 2-åringer som er 6 cm og som er 16 cm i samme område

Dose rate (KJm⁻² h⁻¹) and total dose (KJm⁻²) of UV-B, UV-A and PAR provided to larvae.

<p>Cod larvae (<i>Gadus morhua</i>) were exposed to two different light conditions (UV-B and Control) for 15 hours before the behavior experiments. Measurements were made at the surface of the water in the exposure tanks.</p

Daily irradiance of UVB, UVA and PAR provided to <i>Thalassiosira weissflogii</i> cultures used as food for <i>Calanus finmarchicus</i>.

<p>Algal cultures received one of three treatments: PAR-only (PAR), PAR plus ambient UVR levels and PAR plus enhanced UVR (UVR+).</p

The number of cells (left axis) and volume of cells ingested by <i>Calanus finmarchicus</i> feeding on <i>Thalassiosira weissflogii</i>.

<p>Algae were cultured under one of 3 different light treatments: PAR only (PAR; Treatment 1), PAR plus ambient UVR (UV; Treatment 2), or PAR plus enhanced UVR (UV+; Treatment 3). Grazing rates were measured over a 48 h feeding cycle. Ingestion rates were significantly higher in the UV+ treatment. No significant difference was found in the grazing rates between the PAR- and ambient-UV-treated cells. Lower case letters indicate homogeneous groups after the ANOVA and post-hoc test (see methods for details).</p

Spectral irradiance for the 3 treatments: PAR (solid line), PAR plus ambient UVR (dotted line), and PAR plus enhanced UVR (dashed line) measured inside the Teflon bags that were used for culturing the algae.

<p>Spectral irradiance for the 3 treatments: PAR (solid line), PAR plus ambient UVR (dotted line), and PAR plus enhanced UVR (dashed line) measured inside the Teflon bags that were used for culturing the algae.</p