Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/12295
Do artificial reefs reduce the accumulation of feeding remains around mariculture cages in Skutulsfjörður?
It is essential that mariculture continues to expand in order to meet the needs of the growing global demand for fish supply. As a result of industrial growth, there has been an increase in negative impacts on the environment near mariculture netpens. Such negative impacts include organic effluents, which are the feeding remains and feces that are released from the netpens. One possible solution for this problem is the use of artificial reefs below the netpens. Artificial reefs intend to attract various organisms that feed off the excess of the organic matter and reduce its accumulation.
In this research two artificial reefs were built and deployed, one below the mariculture netpen: artificial reef farm (ARF), and one in a control site 240 meters away: artificial reef control (ARC). In order to assess their biofiltration capability, the organisms that were associated with the artificial reefs were examined. During each sampling dive, wild stock assessment of bigger fauna was conducted and four plates that were made from the same material as the reefs’ tubes were removed. The species that grew on the plates were then identified and quantified. In total, there were thirty-two plates for eight sampling dives.
Our results show that the reefs attracted both invertebrates, sessile and motile, as well as wild fishes. The succession of sessile species appeared from the fourth sampling dive onwards. During the research, the presence of sessile species increased in number and size. Motile species were also present in both reefs. Their succession was early, appearing in the first sampling dive. The number of motile species was greater in the farm site. Wild fishes were present only in the farm site, while Hydrozoa was present only in the control site and grew extensively on the reef. Overall, species richness was greater at the farm site. Standard ANOVA test could not be applied as it was unsuccessful in finding a significant correlation between the two sites. Instead, Repeated Measures ANOVA was used to show that there was a significant difference in plate (fouling) cover between ARF and ARC. Also, the effect of time on growth indicates that time had a significant influence on this factor, and that there was a significant difference in growth rate between the sites.
It can be concluded that the organisms found on the reefs, and the wild fish around it, showed the reefs’ capability of being used as biofiltration as they successfully attracted organisms that fed off the feeding surplus from the netpens. However, the full extent of their filtration capability is still to be determined.
KEY WORDS: mariculture, netpens, artificial reefs, biofiltration, organic effluents
Verkefnið er lokað til 01.01.2016