title: Megafaunal community structure of Andaman seamounts including the Back-arc Basin--a quantitative exploration from the Indian Ocean.
abstract: Species rich benthic communities have been reported from some seamounts, predominantly from the Atlantic and Pacific Oceans, but the fauna and habitats on Indian Ocean seamounts are still poorly known. This study focuses on two seamounts, a submarine volcano (cratered seamount--CSM) and a non-volcano (SM2) in the Andaman Back-arc Basin (ABB), and the basin itself. The main purpose was to explore and generate regional biodiversity data from summit and flank (upper slope) of the Andaman seamounts for comparison with other seamounts worldwide. We also investigated how substratum types affect the megafaunal community structure along the ABB. Underwater video recordings from TeleVision guided Gripper (TVG) lowerings were used to describe the benthic community structure along the ABB and both seamounts. We found 13 varieties of substratum in the study area. The CSM has hard substratum, such as boulders and cobbles, whereas the SM2 was dominated by cobbles and fine sediment. The highest abundance of megabenthic communities was recorded on the flank of the CSM. Species richness and diversity were higher at the flank of the CSM than other are of ABB. Non-metric multi-dimensional scaling (nMDS) analysis of substratum types showed 50% similarity between the flanks of both seamounts, because both sites have a component of cobbles mixed with fine sediments in their substratum. Further, nMDS of faunal abundance revealed two groups, each restricted to one of the seamounts, suggesting faunal distinctness between them. The sessile fauna corals and poriferans showed a significant positive relation with cobbles and fine sediments substratum, while the mobile categories echinoderms and arthropods showed a significant positive relation with fine sediments only.
authors.affiliation: National Institute of Oceanography (CSIR), Dona Paula, Goa, India. sabya_aqua@rediffmail.com
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Sautya
authors.forename: Baban
authors.initials: B
authors.lastname: Ingole
authors.forename: Durbar
authors.initials: D
authors.lastname: Ray
authors.forename: Sabine
authors.initials: S
authors.lastname: Stöhr
authors.forename: Kiranmai
authors.initials: K
authors.lastname: Samudrala
authors.forename: K A Kamesh
authors.initials: KA
authors.lastname: Raju
authors.forename: Abhay
authors.initials: A
authors.lastname: Mudholkar
mesh_terms: D000818:Animals; D037421:Anthozoa; D044822:Biodiversity; D017753:Ecosystem; D005843:Geography; D019015:Geologic Sediments; D019156:Indian Ocean; D008386:Marine Biology; D012111:Residence Characteristics; D014741:Video Recording