| The artificial reef areas and control area in Zhuwang Harbor, Laizhou, Shandong,were monthly investigated from May2010to November2010and from March2011to April2011(In this paper, the artificial reef area constructed in2008was denoted asA1and that constructed in2009as A2. The control area was denoted as CA). In orderto preliminarily evaluate the ecological restoration effect of artificial reefs inZhuwang Harbor, related environmental factors, the community structure of thenektons and its seasonal changes, and the feeding ecology of Synechogobiusommaturus—the dominant species were studied. Results can be articulated asfollowing.Studies on environmental factors show, each quality index of the sea water inZhuwang Harbor appears obvious seasonal changes, but can be still up to the1stor2ndclass of the state ’s quality standard. The contents of BOD and inorganic nitrogen arerelatively higher, which indicates slight eutrophication of the sea area. Compared withthe control area, DOCs of the artificial reef areas are lower, whereas their BOD andactive phosphate indexes higher in several investigation months. This is possiblyrelevant to the setting of artificial reefs. The artificial reefs putting into the bottom ofthe sea caused the ranges of upwelling, thereby bringing nutrients up to the upperlayers. Primary productivity of that sea area increased as a result. This is correspondedwith that the contents of chlorophyll a of the artificial reef areas are relatively higherthan that of the control area. In addition, based on the study of the N: P ratio, it’sfound the overall sea area is in the nitrogen limitation condition, but the setting ofartificial reef to som extent relieved this situation. In conclusion, the artificial reefs’ecological benefit can not appear in the near future, however, it can be clearly foundthat water quality of the artificial reef areas is better than the control area and theartificial reefs displayed good cushioning influence against water qualitydeterioration. As for studies on the nektons, results show that the nekton species at the artificialreefs areas is much more abundant (about1.45times more) than that at the controlarea. The Margalef species richness index, Shannon-Wiener diversity index andPielou evenness index of the artificial reef areas are all higher than the control area.Additionally, CPUEs of the artificial reef areas are also significantly higher than thecontrol area: CPUE of A1and A2is2or1.5times higher than that of CA, respectively.Through comprehensive comparison, Synechogobius ommaturus and Charybdisjaponica are determined as the dominant species, among which CPUE of Charybdisjaponica at A1and A2is up to3.7or3.9times as high as that at CA. This resultspreliminarily indicated fish aggregation effect of artificial reefs and obviousimprovement of the community structure of the nektons at the artificial reef areas.RDA analysis revealed pH, inorganic nitrogen, salinity and water temperature are allthe main impact-factors for the nektons distribution.Exhibited by the studies on the feeding ecology of Synechogobius ommaturus—the dominant species in the sea area of Zhuwang Harbor, the species belongs totypical benthic animal-feeding fish and feeds on23kinds of living feeds, amongwhich Musculus senhousei, Nereis succinea, Latreutes planirostris and so on aremajor. Also, it has been found that Synechogobius ommaturus displays seriousself-mutilation behavior. Furthermore, the rate of empty stomach and the averagefullness index of this species both appeared obvious seasonal and inter-annualvariation, probably because time has not pasted so long after the artificial reefs puttinginto the sea area and therefore the construction of the living feeds communities hasnot been mature. Compared with the number of living feeds species in2010, that in2011is obviously higher. This result indicates the artificial reefs’ aggregation effect onliving feeds. CCD analysis showed, pH, COD and water temperature are the mainimpact-factors for the living feeds distribution. |
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