Environmental drivers of benthic community structure in a deep sub-arctic fjord system

Molina, Èric Jordà; Silberberger, Marc J.; Kokarev, V. N.; Reiss, Henning

doi:10.1016/j.ecss.2019.05.021

Cited by 19 publications

(14 citation statements)

References 57 publications

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“…In general, much of the same taxa composition was observed in both dives for depth zones below the sill depth. The largest difference in megabenthic community composition was found between the deepest and shallowest zones for both dives, and similar trends have been observed in other surveys (Starmans et al, 1999;Sswat et al, 2015;Molina et al, 2019). In the present study, the Basin Zone was characterized more by sessile fauna (e.g., P. squamatus, Acesta excavata, Hymenodiscus coronata, and sponges) and M. tenuimana, whereas the Above Sill Zone was more dominated by echinoderms and anemones.…”

Section: Community Patterns With Depth and Distance From The Sillsupporting

confidence: 90%

“…With limited mixing within the water column, dissolved oxygen levels tend to decrease with depth, distance from the sill, and over time until a renewal event occurs, whereby more oxygenated ocean water mixes with fjord water. In general, faunal diversity and species richness is seen to decrease with increasing distance from the coastal regions and increasing water depth (Buhl-Mortensen and Høisaeter, 1993;Holte et al, 2004;Molina et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…It is well documented that fjord communities are influenced by both the coast-fjord and/or depth gradients (Buhl-Mortensen and Høisaeter, 1993;Holte et al, 2004;Włodarska-Kowalczuk and Pearson, 2004;Storesund et al, 2017;Molina et al, 2019). The interaction between the ocean water and the fjord system helps carry seawater into the fjord, which aids in the distribution of fauna, organic nutrients, and inorganic material (Buhl-Mortensen and Høisaeter, 1993;Holte et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Density stratification between upper and bottom water masses is often observed and the inner basin(s) below the sill depth becomes isolated from the adjacent coastal system. This stratification leads to relatively stable temperatures and salinities within the basins (Renaud et al, 2007;Drewnik et al, 2016;Molina et al, 2019). With limited mixing within the water column, dissolved oxygen levels tend to decrease with depth, distance from the sill, and over time until a renewal event occurs, whereby more oxygenated ocean water mixes with fjord water.…”

Section: Introductionmentioning

confidence: 99%

“…Deep-water stagnation is thought have a major influence on fjord basin communities, where lower oxygen concentrations can negatively impact the community structure and species composition (Blanchard et al, 2010;Molina et al, 2019), resulting in lower species richness with lower oxygen levels (Buhl-Mortensen and Høisaeter, 1993). In periods of hypoxic and anoxic conditions, where the oxygen concentration is <2.1 mL L −1 , defaunation of macrofauna and changes in faunal assemblages have been observed within the basin (Holte et al, 2005;Molina et al, 2019). In extreme cases of deoxygenation and strong stratification, a rise of acidification within fjord basins can occur (Jantzen et al, 2013), particularly if water exchange with adjacent coastal systems is insufficient.…”

Section: Introductionmentioning

confidence: 99%

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Drivers of Megabenthic Community Structure in One of the World’s Deepest Silled-Fjords, Sognefjord (Western Norway)

et al. 2020

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The Sognefjord is the longest (205 km) and deepest (1308 m) fjord in Norway, and the second-longest in the world. Coast-fjord exchange in Sognefjord is limited by a seaward sill at 170 m water depth, which causes a clear stratification between water masses as the dense oxygen-poor basin water mixes slowly with the well-oxygenated water directly above from the coastal ocean. Due to the homogeneity and limited variability in the deep-water, the deep slopes of Sognefjord represent the ideal setting to study how abiotic factors influence the deep-water benthic community structure. During the summer of 2017, two remotely operated vehicle (ROV) video transects were performed to compare the megabenthic community behind the sill (water depth: 1230 to 55 m; transect length: 1.39 km; distance from sill: ∼17 km) and within the central fjord (water depth: 1155-85 m; transect length: 2.43 km; distance from sill: ∼79 km). Accompanying conductivity-temperature-depth (CTD) deployments were made to measure the in situ abiotic factors and nutrient concentrations at each transect location, while the substrate characteristics (percent cover of soft and hard exposed substrate) were documented from the video footage. Here, Sognefjord's megabenthic community composition, distribution, and species richness were analyzed in relation to abiotic factors (e.g., depth, salinity, dissolved oxygen, chlorophyll a concentration, and percent cover of hard and soft substrata) within the fjord. Basin communities were homogeneous and characterized by sponges, echinoderms, and crustaceans, whereas the shallower regions were dominated by mobile scavengers. Contrary to other fjord-based studies, species richness and diversity were stable in the fjord basin and decreased with proximity to the sill, decreasing water depth, and at the boundary between intermediate and basin water. The findings demonstrate that highly stratified fjords support stable communities in their basins; however, further research is needed to investigate the influence water mass dynamics have on silled-fjord megafauna communities.

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Section: Community Patterns With Depth and Distance From The Sillsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Drivers of Megabenthic Community Structure in One of the World’s Deepest Silled-Fjords, Sognefjord (Western Norway)

et al. 2020

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Benthic scavenger community composition and carrion removal in Arctic and Subarctic fjords

et al. 2020

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In high latitude coastal regions, benthic scavenger communities are largely composed of invertebrates that play a key role in the cycling of organic matter. Factors including temperature and depth can structure Arctic and Subarctic fjord benthic communities, but the response of scavenging communities to these factors is poorly known. To address this, we compared scavenging fauna in eight fjords with different physical characteristics in Svalbard and northern Norway using time-lapse imagery of scavengers consuming Atlantic herring (Clupea harengus) bait. Fjords influenced by relatively warm Atlantic waters, both in Norway and Svalbard, had high scavenger richness. However, Svalbard fjords with negative bottom temperatures had the lowest species richness and were dominated by lysianassoid amphipods and ophiuroids. In these cold Svalbard fjords, the mean carrion removal rates were almost 20 times higher than mean values noted elsewhere, except in the warm Norwegian fjord Kaldfjorden. Amphipods and ophiuroids quickly reduced the bait to bones (207.6–304.7 g removed per hour (g h−1); mean 290.6 ± 7.3 g h−1, n = 4) in cold Svalbard fjords. In the warmer Svalbard fjords, carrion removal rates were low (0–51.5 g h−1; mean 14.6 ± 9.0 g h−1, n = 5). Carrion removal rates in Kaldfjorden were higher than other Atlantic Water influenced fjords (132.1 and 372.5 g h−1, n = 2) owing to the scavenging activity of Atlantic cod (Gadus morhua). The results demonstrate potential ecosystem responses to warming in Arctic and Subarctic fjords, particularly effects related to range expansion of boreal species.

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Changes in benthic communities in Blagopoluchiya Bay (Novaya Zemlya, Kara Sea): the influence of the snow crab

Udalov,

Anisimov,

Basin

et al. 2024

Biol Invasions

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Environmental drivers of benthic community structure in a deep sub-arctic fjord system

Cited by 19 publications

References 57 publications

Drivers of Megabenthic Community Structure in One of the World’s Deepest Silled-Fjords, Sognefjord (Western Norway)

Drivers of Megabenthic Community Structure in One of the World’s Deepest Silled-Fjords, Sognefjord (Western Norway)

Benthic scavenger community composition and carrion removal in Arctic and Subarctic fjords

Changes in benthic communities in Blagopoluchiya Bay (Novaya Zemlya, Kara Sea): the influence of the snow crab

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