Abstract
Expanding human activities alongside climate change, the introduction of invasive species and water contamination pose multiple threats to the unique marine ecosystems of the Pechora Sea in the Russian Arctic. Baseline data on biodiversity and responses to environmental change are urgently needed. Benthic decapod crustaceans are globally distributed and play an important role in fisheries, yet their roles in food webs are less understood. In this study, we used an integrated approach combining stomach content analysis and stable isotope analyses (δ13C and δ15N) to examine the trophic niches of three decapod species in the Pechora Sea including the invasive snow crab Chionoecetes opilio and two species of native decapods, the spider crab Hyas araneus and the hermit crab Pagurus pubescens. Stomach contents of 75 decapods were analysed (C. opilion = 23; H. araneusn = 9; P. pubescensn = 43), and 20 categories of prey items were identified with the most frequently occurring prey items being bivalve molluscs (Ciliatocardium ciliatum, Ennucula tenuis, Macoma calcarea), polychaetes, crustaceans and plant debris. Bayesian ellipse analyses of stable isotope signatures (n = 40) revealed that C. opilio displays an overlapping trophic niche with the two native decapods, providing direct evidence that the invader likely competes for food resources with both H. araneus and P. pubescens. As such, the presence of this invasive species could hold important consequences for trophic interactions, benthic ecosystem functioning and biodiversity. Microplastics were also found to be a likely stressor on this ecosystem, as 28% of all stomachs contained digested microplastics among other items. Long-term studies of benthic ecosystem structure and functioning are now needed to more fully understand the extent to which this new competitor may alter the future biodiversity of the Pechora Sea alongside the additional stressor of digested plastics.
Highlights
Pechora Sea ecosystems: conservation priorities and challengesMarine ecosystems of the Pechora Sea, in the south-eastern basin of the Barents Sea (Fig. 1), are characterised by a number of distinct features including relatively shallow water depths, significant impacts of continental runoff from the Pechora river, partial isolation from the open sea, a relatively short ice-free period, and a historically low level of anthropogenic activities (Nikiforov et al 2005; Sukhotin et al 2019)
Collected crabs were a mixture of males and females with a predominance of males in all three species: 13 males and 10 females of C. opilio; 7 males and 2 females of H. araneus; 32 males and 11 females of P. pubescens (Supplementary material, Online Resource 1)
C. opilio and H. araneus were of a similar size group: C. opilio average carapace length (CL) was 32.0 ± 3.75 mm, ranging from 27 to 32 mm; H. araneus average CL was 47.0 ± 8.44 mm (28–58 mm); and P. pubescens were 4–5 times smaller with CL of 8.5 ± 2.62 mm (4.0–12.5 mm)
Summary
Pechora Sea ecosystems: conservation priorities and challengesMarine ecosystems of the Pechora Sea, in the south-eastern basin of the Barents Sea (Fig. 1), are characterised by a number of distinct features including relatively shallow water depths, significant impacts of continental runoff from the Pechora river, partial isolation from the open sea, a relatively short ice-free period, and a historically low level of anthropogenic activities (Nikiforov et al 2005; Sukhotin et al 2019). Pechora Sea ecosystems: conservation priorities and challenges. Rapid increases in human activities such as oil and gas extraction, shipping, tourism, combined with climate change, introduction of invasive species and the release of contaminants are predicted to have a cumulative impact on the unique marine ecosystems of the Pechora Sea (Sukhotin et al 2019; Semenova et al 2019). Recent assessments of the current state and future challenges of the Pechora Sea ecosystems (Sukhotin et al 2019) highlighted the importance of biodiversity studies in providing baseline data for future conservation and sustainable management activities in the region. Investigations of food webs and trophic relationships between species are important for better understanding of biodiversity and broader ecosystem functioning.
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