Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea
Background High primary productivity in the midst of high toxicity defines hydrocarbon seeps; this feature usually results in significantly higher biomass, but in lower diversity communities at seeps rather than in the surrounding non-seep benthos. Qualitative estimates indicate that this dichotomy...
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PeerJ Inc.
2019-08-01
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| Online Access: | https://peerj.com/articles/7398.pdf |
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| author | Arunima Sen Cheshtaa Chitkara Wei-Li Hong Aivo Lepland Sabine Cochrane Rolando di Primio Harald Brunstad |
| author_facet | Arunima Sen Cheshtaa Chitkara Wei-Li Hong Aivo Lepland Sabine Cochrane Rolando di Primio Harald Brunstad |
| author_sort | Arunima Sen |
| collection | DOAJ |
| description | Background High primary productivity in the midst of high toxicity defines hydrocarbon seeps; this feature usually results in significantly higher biomass, but in lower diversity communities at seeps rather than in the surrounding non-seep benthos. Qualitative estimates indicate that this dichotomy does not necessarily hold true in high latitude regions with respect to megafauna. Instead, high latitude seeps appear to function as local hotspots of both megafaunal diversity and abundance, although quantitative studies do not exist. In this study, we tested this hypothesis quantitatively by comparing georeferenced seafloor mosaics of a seep in the southwestern Barents Sea with the adjacent non-seep seafloor. Methods Seafloor images of the Svanefjell seep site and the adjacent non seep-influenced background seabed in the southwestern Barents Sea were used to construct georeferenced mosaics. All megafauna were enumerated and mapped on these mosaics and comparisons of the communities at the seep site and the non-seep background site were compared. Sediment push cores were taken in order to assess the sediment geochemical environment. Results Taxonomic richness and abundance were both considerably higher at the seep site than the non-seep location. However, taxa were fewer at the seep site compared to other seeps in the Barents Sea or the Arctic, which is likely due to the Svanefjell seep site exhibiting relatively low seepage rates (and correspondingly less chemosynthesis based primary production). Crusts of seep carbonates account for the higher diversity of the seep site compared to the background site, since most animals were either colonizing crust surfaces or using them for shelter or coverage. Our results indicate that seeps in northern latitudes can enhance local benthic diversity and this effect can take place even with weak seepage. Since crusts of seep carbonates account for most of the aggregating effect of sites experiencing moderate/weak seepage such as the study site, this means that the ability of seep sites to attract benthic species extends well beyond the life cycle of the seep itself, which has important implications for the larger marine ecosystem and its management policies. |
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| issn | 2167-8359 |
| language | English |
| last_indexed | 2024-03-09T06:38:07Z |
| publishDate | 2019-08-01 |
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| spelling | doaj.art-4e41ac7dbf9949c6b691412fb11467af2023-12-03T10:55:02ZengPeerJ Inc.PeerJ2167-83592019-08-017e739810.7717/peerj.7398Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents SeaArunima Sen0Cheshtaa Chitkara1Wei-Li Hong2Aivo Lepland3Sabine Cochrane4Rolando di Primio5Harald Brunstad6UiT The Arctic University of Norway, Centre for Arctic Gas Hydrate, Environment and Climate (CAGE), Tromsø, NorwayUiT The Arctic University of Norway, Centre for Arctic Gas Hydrate, Environment and Climate (CAGE), Tromsø, NorwayGeological Survey of Norway (NGU), Trondheim, NorwayGeological Survey of Norway (NGU), Trondheim, NorwayAkvaplan-niva, High North Research Centre, Tromsø, NorwayLundin Norway, Oslo, NorwayLundin Norway, Oslo, NorwayBackground High primary productivity in the midst of high toxicity defines hydrocarbon seeps; this feature usually results in significantly higher biomass, but in lower diversity communities at seeps rather than in the surrounding non-seep benthos. Qualitative estimates indicate that this dichotomy does not necessarily hold true in high latitude regions with respect to megafauna. Instead, high latitude seeps appear to function as local hotspots of both megafaunal diversity and abundance, although quantitative studies do not exist. In this study, we tested this hypothesis quantitatively by comparing georeferenced seafloor mosaics of a seep in the southwestern Barents Sea with the adjacent non-seep seafloor. Methods Seafloor images of the Svanefjell seep site and the adjacent non seep-influenced background seabed in the southwestern Barents Sea were used to construct georeferenced mosaics. All megafauna were enumerated and mapped on these mosaics and comparisons of the communities at the seep site and the non-seep background site were compared. Sediment push cores were taken in order to assess the sediment geochemical environment. Results Taxonomic richness and abundance were both considerably higher at the seep site than the non-seep location. However, taxa were fewer at the seep site compared to other seeps in the Barents Sea or the Arctic, which is likely due to the Svanefjell seep site exhibiting relatively low seepage rates (and correspondingly less chemosynthesis based primary production). Crusts of seep carbonates account for the higher diversity of the seep site compared to the background site, since most animals were either colonizing crust surfaces or using them for shelter or coverage. Our results indicate that seeps in northern latitudes can enhance local benthic diversity and this effect can take place even with weak seepage. Since crusts of seep carbonates account for most of the aggregating effect of sites experiencing moderate/weak seepage such as the study site, this means that the ability of seep sites to attract benthic species extends well beyond the life cycle of the seep itself, which has important implications for the larger marine ecosystem and its management policies.https://peerj.com/articles/7398.pdfArcticCold seepsGISImageryMegabenthosHydrocarbon seepage |
| spellingShingle | Arunima Sen Cheshtaa Chitkara Wei-Li Hong Aivo Lepland Sabine Cochrane Rolando di Primio Harald Brunstad Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea PeerJ Arctic Cold seeps GIS Imagery Megabenthos Hydrocarbon seepage |
| title | Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea |
| title_full | Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea |
| title_fullStr | Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea |
| title_full_unstemmed | Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea |
| title_short | Image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern Barents Sea |
| title_sort | image based quantitative comparisons indicate heightened megabenthos diversity and abundance at a site of weak hydrocarbon seepage in the southwestern barents sea |
| topic | Arctic Cold seeps GIS Imagery Megabenthos Hydrocarbon seepage |
| url | https://peerj.com/articles/7398.pdf |
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