Invertebrate communities of the High Arctic ponds in Hornsund

Abstract

Abstract:How environmental conditions influence current distributions of organisms at the local scale in sensitive High Arctic freshwaters is essential to understand in order to better comprehend the cascading consequences of the ongoing climate change. This knowledge is also important background data for paleolimnological assessments of long−term limno− ecological changes and in describing the range of environmental variability. We sampled five limnologically different freshwater sites from the Fuglebergsletta marine terrace in Horn− sund, southern Svalbard, for aquatic invertebrates. Invertebrate communities were tested against non−climatic environmental drivers as limnological and catchment variables. A clear separation in the communities between the sites was observed. The largest and deepest lake was characterized by a diverse Chironomidae community but Cladocera were absent. In a pond with marine influence, crustaceans, such as Ostracoda, Amphipoda, and calanoid Copepoda were the most abundant invertebrates. Two nutrient−rich ponds were dominated by a chironomid, Orthocladius consobrinus, whereas the most eutrophic pond was dominated by the cladoceran Daphnia pulex, suggesting decreasing diversity along with the trophic status. Overall, nutrient related variables appeared to have an important influence on the invertebrate community composition and diversity, the trophic state of the sites being linked with their ex− posure to geese guano. Other segregating variables included water color, presence/absence of fish, abundance of aquatic vegetation and lake depth. These results suggest that since most of these variables are climate−driven at a larger scale, the impacts of the ongoing climate change will have cumulative effects on aquatic ecosystems.

Synchronized proxy‐based temperature reconstructions reveal mid‐ to late Holocene climate oscillations in High Arctic Svalbard

“…However, when comparing the Svartvatnet chironomid stratigraphy (Fig. ) with the modern dataset (Luoto et al ., ), the phenomenon of bird‐induced eutrophication is not reflected in the chironomid communities of Svartvatnet. Therefore, since our study site is not significantly influenced by birds, it is probable that the long‐term biotic record is driven by the direct impact of climate.…”

“…According to our previous assessment based on contemporary aquatic communities (Luoto et al ., ), the most significant confounding factor for chironomid‐based temperature reconstructions in the study area (Hornsund) is the potential influence of bird‐driven nutrient enrichment. This kind of arctic eutrophication superimposed on the recent climate warming is a typical trend for smaller ponds lying close to the shoreline in Svalbard with increasing sizes of arctic‐nesting birds in their catchment (Luoto et al ., , ).…”

Biogeochemical cycling and ecological thresholds in a High Arctic lake (Svalbard)

“…The chironomid feeding groups, including collector-gatherers and collector-filterers, were based on Merritt and Cummins (1996) and Mandaville (2002). As indicators for bird-impact, we used relative percentages of nitzschioid diatoms (Jones and Birks 2004;Keatley et al 2009) and chironomids typical for lakes with significant bird influence in Svalbard, such as Orthocladius trigonolabis-type, O. consobrinus-type and Metriocnemus eurynotus-type (Brooks and Birks 2004;Luoto et al 2016;.…”

“…In addition, the presence of Micropsectra suggests well-oxygenated hypolimnion, since it is an "oxy-stressor", a genus that requires high oxygen levels (Brodersen et al 2008). An option is that the chironomid response is due to habitat change, since the bird indicators O. trigonolabistype and O. consobrinus-type prefer more productive lakes in Svalbard with aquatic macrophytes present (Brooks and Birks 2004;Luoto et al 2016). An unpublished analysis of a sediment core from the northern basin (RE8 in Ojala et al 2016) showed that while other invertebrate remains were very scarce, ostracods (Podocopida) were numerous, unlike in the southern basin where they were completely absent.…”

Do hyperabundant Arctic-nesting geese pose a problem for sympatric species?

“…At a reservoir in Pennsylvania, Snow Geese contributed 93% of the phosphorus and 44% of the nitrogen loads (Olson et al 2005). In Arctic wetlands, aquatic invertebrate abundance is higher in nutrient rich ponds (Brodersen and Anderson 2002;Luoto et al 2016). Although benefits of goose-induced nutrient input into Arctic wetlands have been suggested (Alisauskas and Kellet 2014) there is limited evidence to suggest either positive or negative impacts on invertebrate communities.…”