Health Assessment Of Benthic Habitats Based On Macrobenthos In Three Mariculture Bays

Macrobenthos plays a vital role in maintaining ecosystem functions.Moreover,their abundance and wide distribution,long life cycle,sensitivity to the environment,and direct contact with sediments,have contributed to the adoption of macrobenthic features for monitoring and assessing changes in the marine environment,and ecosystem health.In this paper,the community structure and distribution characteristics of macrobenthos in three typical aquaculture bays in the north of China were analyzed.The health status of benthos in the mariculture area was evaluated by Shannon-wiener biodiversity indicator(H’),AZTI’s Marine Biotic Index(AMBI),Multivariate-AZTI’s Marine Biotic Index(M-AMBI)and abundance/biomass curve(ABC curve).The main conclusions were as follows:1. Based on survey data from Jiaozhou Bay in July 2017,the ecological characteristics of macrobenthos were analyzed using cluster analysis,and biodiversity and M-AMBI methods.A total of 64 species were identified,including 25 species of Polychaeta,23 species of crustaceans,nine species of mollusks,and seven species belonging to other benthic groups and echinoderms.The average biomass and abundance were 70.0 g/m~2 and 132 ind./m~2,respectively.There were three dominant species,including Ruditapes philippinarum,Nephthys oligobranchia,and Nemertinea.The ranges of the Margalef species richness index,Shannon-Wiener diversity index(H′),Pielou’s evenness index,and Multivariate-AZTI’s Marine Biotic Index(M-AMBI)were0.69～3.77,0.67～3.12,0.25～1.00 and 0.26～0.60,respectively.According to the results of the cluster analysis,the macrobenthos at the 15 stations could be clustered into three infaunal communities at 15%similarity.The station communities with a higher density of clam larvae were divided into the same community,clustering results were related to Philippine clam farming.The H′and M-AMBI analysis showed that the benthic habitats tended to be moderately disturbed and the ecological status tended to Good or Poor.2. The species composition,dominant species,abundance,biomass and community structure were investigated in the Xiaoqing River estuary of Laizhou Bay in July,August and September 2019,and analyzed by abundance/biomass curves,AZTI’s Marine Biotic Index(AMBI)and Multivariate-AZTI’s Marine Biotic Index(M-AMBI)to assess the benthic habitat health status.A total of 64 macrobenthic species were recorded,including24 Polychaeta,19 Crustaceans,17 Mollusks,and 4 species belong to other benthic groups.There were seven dominant species including Potamocorbula laevis,Moerella iridescens,Nassarius semiplicatus,Mactra veneriformis,Nephthys oligobranchia,Mediomastus californiensis,Ogyrides orientalis,Philyra acutidens and Ampelisca brevicornis.The cluster analysis of community structure and multidimensional scale analysis revealed that macrobenthos communities in the study area in July were divided into 3 groups with 10%similarity,4 groups with 18%sumilarity in August and 3 groups with 19%similarity in September,with lower community structure similarity in three surveys.The results of the abundance/biomass curve showed that the macrobenthic community was undisturbed.The AMBI and M-AMBI Index analysis showed that the benthic habitats tended to be no disturbed or slightly disturbed and the ecological status tended to High or Good.3. From May to September 2019,five surveys of macrobenthos were conducted in different mariculture areas of Sanggou Bay to understand the impact of aquaculture on the environment of the benthic ecosystem.The community characteristics of macrobenthos,such as species abundance,composition,distribution,and biodiversity were analyzed in different mariculture areas in five surveys,and the health status of the benthos ecosystem in Sanggou Bay was assessed by the Abundance-Biomass Curves(ABC Curves),AZTI’s Marine Biotic Index(AMBI)and Multivariate-AZTI’s Marine Biotic Index(M-AMBI).A total of 56 species were identified,including 31 species of Polychaetes,10 species of Crustacea,9 species of Mollusca,3 species of Echinodermata and 2 species of other taxa.The dominant species were Lumbrinereis sp.,Tharyx multifilis,Notomastus latericeus,Mediomastus californiensis,Amaeana occidentalis,Paranthura japonica,Scoloplos sp.,Potamocorbula laevis,Glycinde gurjanovae,Cirolana japonensis.During the breeding period,the community diversity index H’of the caging culture area and the bivalves culture area showed a downward trend,indicating that bivalves culture activities and cage culture activities have caused excessive accumulation of organic particles in the sediments,and the habitat disturbance of the bivalves culture area was affected by shellfish deposition rates.The AMBI and M-AMBI Index analysis showed that the benthic habitats tended to be slightly disturbed or moderate disturbed and the ecological status tended to High or Moderate.4. Through an ecological survey of the coastal waters of the Xiaoqing River estuary in Laizhou Bay,a comprehensive evaluation model was established based on the structure and function of the ecosystem.The results show that the ecosystem is in a healthier state and the water quality environment is unstable due to the influence of the Xiaoqing River.In future investigations,monitoring of water quality and environment should be strengthened.