Early summer near-shore fish assemblage and environmental correlates in an Arctic estuary

Abstract

Knowledge of reference conditions and species-environment associations is required to ascertain ongoing aquatic biodiversity changes in Arctic regions. The objective of this study was to establish a baseline of fish community structure (species composition, incidence and relative abundance) in relation to salinity, pH and temperature gradients in an Arctic estuary, the Husky Lakes, Canada. Sampling involved an early-summer, standardized, experimental netting survey around the entire perimeter of all estuary basins and peninsulas. Detrended canonical correspondence analysis (DCCA) was used to evaluate species-environment associations. The ecosystem sustains an abundant and diverse fish community, characterized by co-dominance of coregonids and a marine schooling fish, Clupea pallasii, and high abundance of freshwater/freshwater-amphidromous species in the innermost basins. Highest richness and total abundance were related to mixing conditions, warmest temperatures, connectivity to nearby ecosystems, and diversity in species life histories. Salinity determined spatial patterns of fish species abundance and distribution. The incidence of freshwater fish was limited by the availability of low salinity habitat and potential community interactions. These fish, particularly Salvelinus namaycush and Thymallus arcticus, are considered as the most vulnerable to changes in freshwater habitat availability. The fish assemblage reflects environmental information from surrounding fluvial, freshwater, coastal marine and catchment ecosystems, and is thus a prime candidate for monitoring environmental change in the region. The results provide a benchmark against which future studies of fish communities can be compared to evaluate potential effects of climate change and anthropogenic development on fish populations from Husky Lakes and similar Arctic aquatic ecosystems.Crown

Heterogeneity of aquatic ecosystems in a developing city for construction of civilized freshwater ecology, China

“…Biodiversity and IBI are the principal parameters often used to characterize changes in aquatic community structure (Cai et al, ; Roux, Harwood, Zhu, & Sparling, ). To further analyse the spatial characteristics of aquatic communities and identify areas with aquatic ecosystems severely degraded in Jinan, using biodiversity and IBI as biological factors, the spatial cluster analysis was conducted with the RF method based on Sections 4.3 and 4.4, as shown in Figure .…”

Arctic grayling (Thymallus arcticus) in saltwater: a response to Blairet al. (2016)

“…Arctic grayling are routinely—albeit in low densities—captured in nearshore coastal waters off the northern coast of Alaska (Moulton and Fawcett, 1984; Craig et al ., 1985; Wiswar and West, 1987; Fruge et al ., 1989; Griffiths et al ., 1998) and Canada (Bond and Erickson, 1992; Roux et al ., 2016). It is presumed that Arctic grayling will enter brackish lagoons with salinities <4 ppt to forage or move between river drainages (West et al ., 1992; Griffiths et al ., 1998).…”

“…It is presumed that Arctic grayling will enter brackish lagoons with salinities <4 ppt to forage or move between river drainages (West et al ., 1992; Griffiths et al ., 1998). Within-summer forays into these habitats tend to occur earlier in the open-water season, when salinity levels are lower (Moulton and Fawcett, 1984; Griffiths et al ., 1998), and across habitats within an estuary the abundance of Arctic grayling is negatively associated with salinity (Roux et al ., 2016). Four ppt does not appear to be the upper salinity limit of Arctic grayling tolerance; Moulton and Fawcett (1984) report catches of Arctic grayling off Oliktok Point in the Arctic Ocean (70.509°, −149.863°) in waters up to ~18 ppt.…”

“…Arctic grayling are described as having a ‘strict(ly) freshwater existence’ (pp 1, 5 and 9), and the authors suggest that ‘Arctic grayling have lost the ability to execute the necessary osmoregulatory mechanisms to cope with higher salinity environments.’ Although Arctic grayling is indeed a freshwater species, there is evidence that some populations can tolerate saline waters. A ‘strictly freshwater existence’ would preclude the use of any brackish (0.5–29 ppt) habitats; however, in the Arctic this species is known to move through brackish waters during migration (West et al ., 1992) in coastal watersheds, and is routinely captured in samples collected in brackish estuaries (Moulton and Fawcett, 1984; Craig et al ., 1985; Wiswar and West, 1987; Fruge et al ., 1989; Bond and Erickson, 1992; Griffiths et al ., 1998; Roux et al ., 2016). It is not widely recognized that Arctic grayling use saline waters, and it is our intent to provide a brief introduction to this concept and explore the implications for Blair et al .…”

A global assessment of fish estuary associations: A numerical approach to assessing estuary‐associated fish functional guilds

“…The analysis of fish communities in terms of estuarine use functional guilds has been widely applied to estuarine ecosystems globally, spanning all marine zoogeographic regions and including the Arctic (e.g. Roux et al., 2016), temperate north‐east Pacific (e.g. Allen et al., 2006), temperate north‐west Pacific (e.g.…”