INFLUENCE OF ARTIFICIAL REEF CONSTRUCTION ON NUTRITION AND WATER QUALITY IN OFF-SHORE AREA OF SHENGSI, ZHEJIANG

Abstract

Zhejiang Fishing Ground is one of the most productive sea area in China.Zhejiang province,which provides high quality habitats for many marine organisms and has numerous islands waters,colonizes hundreds of species(such as fish,shrimp,shellfish,algae ect.) in the waters.Zhejiang sea waters are nutrient prosperous area,being rich in marine primary productivity,and have a wide range of flow lines and water masses between the turn of the intersection of growth and decline.But after a large-scale over-intense blind fishing,fisheries resources in the waters are recession seriously,the marine environment also have been damage.In order to improve the ecological environment quality,and to conserve fishery resources of Zhejiang coastal fishing grounds,the local governments of Shengsi county had begun to implement artificial reef construction projects,and then the project was going to be planning in 2003.The first phase of the project was successfully implemented at the end of 2004,including different types of concrete artificial reefs and vessel-reefs with a total volume of 14 985 cubic meters deployed in the middle of Dongku and Luhua sea area(30 ° 47'—30 ° 49'N,122 ° 39'—122 ° 41'E) from 2005 to the early year of 2006,with a total reef monomer of 554.Marine environment quality might be significant changed after deploying so many artificial reefs.So far,domestic research focused mainly on the three major benefits,site selection,layout,leisure fisheries,proliferation of resources and so on,however,very few relevant impacts on nutrients and water quality after artificial reef construction is reported.Moreover,understanding and grasping the nutrient content,distribution and its impact factors were of great significance to scientific evaluation and forecasting capacity of the area and nutrition status,marine environmental protection,utilization and management.Based on the experimental data from 11 voyages carried out in Shengsi artificial reef areas and near waters in 2003—2007,the seasonal variations of nitrogen,phosphorus and water quality after the deployment of artificial reefs were studied in comparative ways between artificial reef areas and control areas,and the assessment for water quality were discussed.The results show that the majority of inorganic nitrogen is in the threshold or below the minimum threshold,and the content of active phosphate is over standard seriously.The value of N/P is in the range of 0.6280—6.7635.The water quality in Shengsi artificial reef area is nitrogen restriction,dissolve oxygen is not the limiting factor in the areas.The ecological effects could not be reflected in the short term after the deployment of artificial reefs.The water quality of the artificial reef area is better than the control area.The enrichment strength for P is greater than N in the waters,and the impact of artificial reef construction on regenerated production is significant and have lower contribution to new production.