Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8886178 | Journal of Sea Research | 2018 | 11 Pages |
Abstract
Recent reports have questioned a decline in the S. droebachiensis in the Oslofjord, similar to what was observed to occur in the Norwegian coastal population of S. droebachiensis after the 1990s. In surveys from 2013 we collected data on urchin density, test diameter, early urchin settlement and Gonad Index and created a framework in order to investigate if the current Inner Oslofjord populations of S. droebachiensis are different from surveys conducted in 1979 and 1992. This study found significant differences in density, diameter and settlement over time. Highest density in 1992 was at 10 and 15Â m, while being at 20Â m in 2013. Urchin diameter at the station with most urchins was on average 5Â cm in 1992 compared to 3Â cm in 2013. Settlement differed both between the number of settlers between 1992 and 2013, and season for highest settlement (summer in 1992, and autumn in 2013). The inner Oslofjord sea urchin data indicate a still healthy population, although environmental data (as temperature and salinity) have changed to less favorable conditions for this species.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Oceanography
Authors
Fredrik Oulie Nyhagen, Hartvig Christie, Kjell Magnus Norderhaug,