Recruitment of benthic invertebrates in high Arctic fjords: Relation to temperature, depth, and season

Abstract

In the high Arctic, recruitment of hard‐bottom benthic organisms has been studied at single locations, but little is known about how it varies spatially or temporally, or how it is influenced by abiotic factors. In this study, settlement plates were simultaneously deployed at five locations in three Svalbard (Norway) fjords at depths ranging from 7 m to 215 m. Recruitment was significantly different among fjords and among locations within a fjord. Recruits at each site co‐occurred randomly even though interspecific overgrowth was observed. This finding provides further evidence that there is not necessarily a relationship between non‐random co‐occurrence and interspecific competition, such as is traditionally assumed for other isolated, island‐like habitats. We found significantly lower recruitment in an Arctic‐influenced fjord than in more Atlantic‐influenced fjords. The abundance and richness of recruits was significantly lower in fall‐winter than in spring‐summer, but the spirorbid Circeis armoricana recruited in high abundance in fall‐winter. Both the abundance and taxonomic richness of recruits declined exponentially with depth, with the hydroid Stegopoma plicatile dominating at 215 m in an Atlantic‐influenced fjord. The most abundant recruiting taxa (C. armoricana, Semibalanus balanoides, Harmeria scutulata, Celleporella hyalina) can be described as pioneer (early‐succession) species. Crustose coralline algae, a slow‐growing superior competitor, also recruited at one location. Recruitment in Svalbard is highly variable, both spatially and temporally, and our results show the influence of local factors such as adult species composition.

Arctic coastal benthos long-term responses to perturbations under climate warming

“…Colonization rates of high-latitude systems are generally much slower than at lower latitudes [10,23]. Yet, colonization patterns observed in other regions appear to hold also in the Arctic, with comparatively faster growing species colonizing more readily than slower growing, and often longer lived, species with a full benthic life cycle [24,25]. Furthermore, early colonizers may either be motile taxa that can migrate to disturbed areas to graze on newly established recruits [10], or short-lived sessile opportunists [26].…”

Recruitment of Arctic deep‐sea invertebrates: Results from a long‐term hard‐substrate colonization experiment at the Long‐Term Ecological Research observatory HAUSGARTEN

“…The first metazoan species to be visible on our panels was the hydroid H. arctica. Hydroids are often the first recruiting species in the marine Arctic (Ronowicz et al 2008), including in shallow Svalbard fjords near our study site (Schmiing 2005;Kortsch 2010;Meyer et al 2017) and on deep-sea substrata (Mullineaux 1988;Beaulieu 2001). Hydroids are easily overgrown, suggesting an opportunistic lifestyle.…”

“…The recovery of benthic communities from iceberg scour has been studied at depths 100-500 m in Antarctica (Gutt et al 1996;Gutt and Starmans 2001;Gutt and Piepenburg 2003), and recovery from natural or experimental disturbance has been studied at 0-70 m in the Arctic (Gutt et al 1996;Beuchel and Gulliksen 2008). However, aside from these studies and one in Svalbard fjords (7-200 m;Meyer et al 2017), to our knowledge, recruitment and succession of Arctic hard-bottom *Correspondence: kmeyer@whoi.edu communities > 70 m depth and generally in the deep sea is virtually unknown.…”

“…The first recruits to a new substratum are usually opportunistic species, with long-lived, slow-growing fauna being absent (Osman 1977). In polar regions, the first recruits are also opportunistic taxa (Bowden et al 2006;Meyer et al 2017), but recruitment is low compared to temperate latitudes (Barnes and Kukli nski 2005;Konar 2007). Recruitment in the Arctic is characterized by similar species richness but lower taxonomic diversity than at similar depths in temperate environments, with the dominant taxa being hydrozoans, bryozoans, barnacles, and serpulid polychaetes (Kukli nski et al 2013).…”

“…In shallow polar environments, recruitment is influenced by environmental factors including seasonality, temperature, ice cover, current flow, and food supply (Stanwell-Smith and Barnes 1997;Meyer et al 2017). This has in some cases led to extreme interannual variation in recruitment, most notably at McMurdo Station, Antarctica (5-55 m depth; reviewed by Dayton et al [2016]).…”