| Artificial shell reef, made of waste shells from aquaculture, is ecological andenvironment-friendly, which could assemble large quantity of macrobenthos. However,the relative researches were mainly about the short-time effects, where the artificialshell reef zone has been established for less than3a. To analyze the long-time effectsand the effects on the adjacent macrobenthic communities, monthly surveys ofmacrobenthos were carried out in the artificial shell reef zone established for more than6a in Shuangdao Bay, Weihai. The benthic ecological quality of the artificial shell reefzone has been analyzed according to ABC (Abundance Biomass Comparison) andAMBI. Three species of macroinvertebrates were selected for biodiffusion experimentunder different levels of temperature and salinity, in order to study the particlereworking of the sediment and distribution of TN and TOC in the sediment. Besides thestructure of macroalgal community on the artificial reef were studied. The resultsshowed that:1. There were69species of macroinvetebrates appearing in the artifical shell reefzone. The number of species, abundance and biomass of macroinvertebrates in theartificial shell reef and the sediment around are all higher than those in the control siteswithout the deployment of shell reef. In the artificial shell reef,24species were foundin the short-time artificial shell reef (deployed for1-2a), the number of species in themiddle-time artificial shell reef (deployed for3-4a) and long-time artificial shell reef(deployed for5-6a) were both37. There were35species appearing in the sedimentaround the artificial shell reef, while the number of species in the control sites was13.The abundance of macroinvertebrates first increased with the time of deployment andthen decreased. The abundance of macroinvertebrates in short-time, middle-time andlong-time artificial shell reefs are679ind/m2,4354ind/m2and3483ind/m2,respectively. The biomass of macroinvertebrates in the artificial shell reef increasedwith the time of the deployment, which are780g/m2,9765g/m2and19522g/m2. The weight percentage of Meretrix meretrix and Protothaca jedoensis increased with thetime of deployment, from15.6%to28.0%, peaked at75.1%. According to the resultsfrom self-organized map, the significant differences of macrobenthic communityappears after three years of the deployment. The time of the deployment and the volumeof the artificial shell reef are the major factors affecting the structure of benthiccommunity.2. The benthic ecological quality of the artificial shell reef zone was analyzedusing M-AMBI (Multivariate-AMBI). The M-AMBI of short-time, middle-time andlong-time artificial shell reef is0.80,0.84and0.91, respectively, which means the statusof ecological quality are high and the ecological quality increased with the time ofdeployment. The M-AMBI of the surrounding infauna community is0.94, higher thanthe maximum of M-AMBI of the shell reef, which means the ecological quality couldbe improved after the deployment of the shell reef.3. The biodiffussion of Cirriformia tentaculata, Ruditapes philippinarum andMacrophthalmus dilatatus were studied under different levels of temperature andsalinity in the laboratory. The results showed that the maximum penetration depth(MPD) of Cirriformia tentaculata, Ruditapes philippinarum and Macrophthalmusdilatatus are14cm,12cm and14cm, respectively. According to the biodiffusioncoefficient computed from the biodiffusion model, the biodiffusive effects ofMacrophthalmus dilatatus is the highest, followed by Ruditapes philippinarum andCirriformia tentaculata. Among the three species, Macrophthalmus dilatatus has themost intensive effects on the vertical distribution of TN and TOC in the sediment.Temperature has effects on the biodiffusion of the three species, and weak effects onCirriformia tentaculata. Salinity has intensive effects on the biodiffussion of Ruditapesphilippinarum and Macrophthalmus dilatatus. The effects of salinity on thebiodiffusion of Cirriformia tentaculata is not significant.4. The sessile macroalgae were surveyed in four artificial reef zones (ARZ) ofShuangdao Bay, in June and August,2013. The name of the ARZs are Jiaming, Beihai,Shengkun and Tonxin. The composition and variation of macroalgal communities insummer were studied, as well as the interactions between the communities andenvironmental factors. Ten transects, measured50cm×50cm, were set randomly ineach ARZ. All the macroalgae in the transect were collected by a SCUBA diver. Besides,underwater videos were taken to provide additional information. Environmental factors,namely, temperature, illustration, pH, DO, salinity, depth, transparency depth, etc. were recorded simultaneously. The samples of algae were identified, measured and weightedin the laboratory, and9species were found totally, with5species of Rhodophyta,2species of Phaeophyta and2species of Chlorophyta. Rhodophyta is the majorcommunity, and the biomass occupied93.69%in June and85.26%in August. Thedifferences of macroalgal communities are significant between the surveys in June andAugust, and the dissimilarities between them is79.65%, based on the analysis ofsimilarities (ANOSIM), and more than90%of dissimilities are contributed by fivespecies, namely, Chrysymenia wrightii, Hterosiphonia japonica, Gracilaria textorii,Sargassum muticum and Ulva pertusa. The algal compositions of Jiaming and Tongxinare similar (R is0.059in June, and0.217in August, p>0.1, ANOSIM). The biomassincreased from164.99g/m2(June) to243.829g/m2(August), while the cover ratedecreased from64.53%–91.20%(June) to52.53%–72.53%(August), except for theARZ of Shengkun. The dominant species is H. japonica in June, and succeeded by C.wrightii in August. According to the results of multidimensional scaling (MDS) andclusters based on Bray-Curtis similarities, the surveyed ARZs could be divided intofour clusters, which are a cluster of ARZs of Jiaming, Beihai and Tongxin in June, acluster of the former three ARZs in August, a cluster ARZ of Shengkun in June, and acluster of the former ARZ in August. Based on principal component analysis (PCA)and redundancy analysis (RDA), water temperature, salinity and bottom illustration arethe major factors affected the variations of the macroalgae community. Temperature isthe most important factor, which interpret45.30%variation of the communities. Thecommunities in June are mainly composed of species of cold and warm temperate, andthose in August mainly composed of species of subtropical and warm temperate. Thesignificance of the relationship between salinity and communities might be the largequantity of raining in August, and the interaction between them might be negligible inthe period of a year. The transparency depth was ca.2.5m in June, however, less than2.0m in August, which meant the light condition might be a limiting factor of thedistribution of the macroalgae. The depth of ARZ in Shengkun is the largest of the fourARZs, and the smallest biomass was found there, which might be the limit of light.Besides, the blooms of fouling organisms, namely Spongiidae, Ciona intestinalis, andObelia sp. in August affected the cover rate. The appearance and enrichment ofPhaeophyta means the mature of the macroalgal communities, however, Phaeophytawas only found at the ARZ of Beihai, deployed ca. seven years. Considering theunderwater light condition, the mature period of the macroalgal communities might be seven years or longer in Shuangdao Bay. |
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