Epibenthic megafauna communities in Northeast Greenland vary across coastal, continental shelf and slope habitats

Abstract

The marine area of Northeast Greenland belongs to the largest national park in the world. Biodiversity assessments and tailored conservation measures often target specific physiographic or oceanographic features of an area for which detailed knowledge on their biological communities is incomplete. This study, therefore, characterizes epibenthic megafauna communities in a priori defined seabed habitats (fjord, shelf, shelf break and slope) and their relationship to environmental conditions in Northeast Greenland waters as a basis for conservation and management planning. Megabenthos was sampled from the Bessel Fjord across the shelf to the upper continental slope between latitudes 74.55°N–79.27°N and longitudes 5.22°W–21.72°W by Campelen and Agassiz trawls at 18 locations (total of 33 samples) at depths between 65 and 1011 m in August 2015 and September 2017. A total of 276 taxa were identified. Gross estimates of abundance ranged from 4 to 854 individuals 1000 m−2 and biomass ranged from 65 to 528 g wet weight 1000 m−2 (2017 only). The phyla Arthropoda and Porifera contributed the most to taxon richness, while Mollusca and Echinodermata were the most abundant, and Echinodermata had the highest biomass of all phyla. Fjord, shelf, shelf break and slope seabed habitats revealed different megafaunal communities that were partly explained by gradients in depth, bottom oxygen concentration, temperature, salinity, and turbidity. The present study provides a current baseline of megabenthos across seabed habitats in Northeast Greenlandic waters and reveals putative connections between Arctic and Atlantic biota.

Spatial occurrence and abundance of marine zooplankton in Northeast Greenland

“…This corresponds well with the tight association of the appendicularian Oikopleura with the Banks and the presence of high biomasses of benthic fauna in these habitats (Table 3, Fig. 5;Fredriksen et al 2020).…”

“…the pluteus of brittle stars (Ophiuroidea), were found mainly on the shallow Banks where a tight pelagic-benthic coupling appears to be established (Fig. 5; Fredriksen et al 2020). On the other hand, bivalve veligers (Mollusca) were abundant in Bessel Fjord but were not recorded on the Banks (Suppl.…”

“…2) and they may represent the shrimps Sclerocrangon ferox and/or Lebbeus polaris. These two shrimp species, together with the northern shrimp Pandalus borealis further offshore, constitute part of the epibenthic fauna in Northeast Greenland (Fredriksen et al 2020). The ophioplutei, veligers, and zoea were the only meroplankton taxa recorded during the TUNU expeditions (Suppl.…”

“…The apparent lack of veligers on the Banks is notable because the settled stages of the pectinoid (Bivalvia) Similipecten greenlandicus were the most dominating species in the epibenthic fauna on the 76N-Bank, in terms of both abundance and biomass (Fredriksen et al 2020). Larvae of bivalves (Mollusca) are common in Subarctic and Arctic plankton from mid-July to September or later (Stübner et al 2016;Michelsen et al 2017;Weydmann-Zwolicka et al, 2021), but the reproduction peak of Similipecten is not known for Northeast Greenland and may have been missed during our brief visits to the area.…”

3D photogrammetry and deep‐learning deliver accurate estimates of epibenthic biomass

“…In marine systems, the measurement of epibenthic biomass is hindered by sub‐tidal access difficulties and is largely reliant on destructive and extractive methods such as trawl surveys (e.g. Fredriksen et al., 2020; Gage & Bett, 2006). Trawl surveys are usually limited to sedimentary, near‐horizontal substrates and, as a destructive practice, are particularly unsuitable for surveying fragile taxa (e.g.…”