Trophic niches of benthic crustaceans in the Pechora Sea suggest that the invasive snow crab Chionoecetes opilio could be an important competitor

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.

The differences in the trophic structure of semi‐enclosed and open coastal communities under the influence of an alien top predator (red king crab in the Barents Sea)

“…Trophic studies based on stable isotopes in the Barents Sea show that P . pubescens is less enriched in 15 N compared to all other co‐occurring decapod species (Gebruk et al, 2021; Paar et al, 2019; Spiridonov et al, 2020; Zmudczyńska‐Skarbek et al, 2015). The diet of P .…”

“…), sea stars, and a native king crab species Lithodes maja (Fuhrmann et al, 2017). In the Pechora Sea, spider crabs, Hyas araneus , and hermit crabs, Pagurus pubescens , have some isotopic niche partitioning, while the relatively recently established non‐indigenous snow crabs Chionoecetes opilio strongly overlap them all (Gebruk et al, 2021).…”

“…Trophic studies based on stable isotopes in the Barents Sea show that P. pubescens is less enriched in 15 N compared to all other cooccurring decapod species (Gebruk et al, 2021;Paar et al, 2019;Spiridonov et al, 2020;Zmudczyńska-Skarbek et al, 2015). The diet of P. pubescens in the Atlantic waters of Canada includes phytobenthos, foraminiferans, amphipods, ostracods, hydroids, bivalves, polychaetes, and ophiurans (Squires, 1990).…”

“…The diet of P. pubescens in the Atlantic waters of Canada includes phytobenthos, foraminiferans, amphipods, ostracods, hydroids, bivalves, polychaetes, and ophiurans (Squires, 1990). In the southeastern Barents Sea (Pechora Sea), this hermit crab is the only decapod species that commonly consume plant material; other frequent items in their stomachs are polychaetes and bivalves while organic debris dominates by volume (Gebruk et al, 2021). Stable isotope studies in the Isfjord also indicate that P. pubescens consume phytobenthos and even plant material of terrestrial origin (Zmudczyńska-Skarbek et al, 2015).…”

Patterns of Benthic Communities in Arctic Fjords (Novaya Zemlya Archipelago, Kara Sea): Resilience vs. Fragility

“…Snow crabs are benthic omnivores, and their diets typically comprise a wide variety of prey types, including macrobenthos, fish and fishery discards, and other crustaceans (Squires and Dawe, 2003). Thus, decapods are largely involved in predator-prey interactions and are known to compete with other species over food and grounds (Boudreau and Worm, 2012;Gebruk et al, 2021). A number of studies showed that predation could shape benthic communities and production processes (Grosholz et al, 2000;de Rivera et al, 2011), and significant shifts in the ecosystem's trophic structure are described due to increased abundance of benthic decapods (Baum and Worm, 2009).…”