Distribution of benthic megafauna in the M2 basin of the western Pacific Ocean and its relationship with nodule storage conditions
Deep-sea basins and plains,the most extensive ecosystems on Earth,harbor vast areas whose seafloor sediments are stored with numerous polymetallic nodules.These nodules not only enrich the spatial complexity and heterogeneity of seafloor habitats but also offer hard substrates for sessile organisms,thereby fostering a unique deep-sea benthic ecosystem.Utilizing high-resolution seabed imagery captured by advanced deep-sea underwater camera,we conducted a comprehensive analysis on the diversity and community structure of benthic megafauna in the M2-B1 region of Beijing Pioneer Hi-Tech Development Corporation's Polymetallic Nodule Contract Area in the western Pacific Ocean,along with their responses to nodule size and coverage.Our findings revealed 25 megabenthos taxa of 9 phyla,including Porifera,Echinodermata,Arthropoda,Cnidaria,Chordata,Annelida,Bry-ozoa,Mollusca,and Foraminifera(Xenophyophore),with an average density of 0.19 ind./m2.The megabenthos phylum list in this region generally same with those found in the Clarion-Clipperton Zone(CCZ)of the eastern Pa-cific Ocean,albeit with slightly lower densities.Our results indicate that polymetallic nodule coverage and size are the major environmental drivers influencing megabenthos taxa abundance in this area.Specifically,we observed a positive correlation between overall megabenthos abundance and nodule coverage,and a negative correlation with nodule size.However,the relationship between different megafauna taxa abundance and nodule coverage/size ex-hibits complex patterns,i.e.,the abundance of sponges and echinoderms increases with nodule coverage,while the densities of echinoderms and molluscs rise with coverage above 64%.Furthermore,the abundance of echinoderms and cnidarians remains stable when nodule size exceeds 3.15 cm.These results preliminarily reveal the distribution pattern and driving factors of megafauna in this region,which will provide important scientific support for future en-vironmental impact assessments of deep-sea mining.
万方数据
维普
