Hydrographic variability in Icelandic waters during recent decades and related changes in distribution of some fish species

Abstract

Valdimarsson, H., Astthorsson, O. S., and Palsson, J. 2012. Hydrographic variability in Icelandic waters during recent decades and related changes in distribution of some fish species. – ICES Journal of Marine Science, 69: 816–825. Seasonal time-series of temperature and salinity around Iceland have been collected, with repeat observations at stations, since the start of the 1970s. After fairly cold years during the early 1990s, a reversal occurred during the mid-1990s and the period from 1996 to 2010 was one with warmer, more saline water in shelf seas around Iceland. Temperatures and salinities have been frequently above the long-term mean in the waters to the south and west of the country, and these conditions have also influenced the shelf area north of the country. Marked changes have also been observed in the distribution of many fish species during this warm period. Southern commercial species have extended farther north (e.g. haddock, monkfish, mackerel), a northern species is retreating (capelin), rare species and vagrants have been observed more frequently (e.g. greater fork beard, blue antimora, snake pipefish, sea lamprey, Ray's bream), and 31 species, from both shelf and oceanic waters, have been recorded for the first time since 1996. The most obvious explanation for these changes in the ecosystem has to be the warming of 1–2°C in the waters south and west of Iceland during the past 15 years.

Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard

“…Atlantic herring Clupea harengus or capelin Mallotus villosus; Alheit & Hagen 1997, Ottersen et al 2001. Marked changes have notably been ob served during the recent warming, since the mid-1990s in the waters north of Iceland (Astthorsson & Gislason 1998, Astthorsson et al 2007, Valdimarsson et al 2012. Our analyses on Calanus finmarchicus (see Supplement 9) suggest that intermediate pathways by which the SPG may affect guillemots may not take place through this copepod (see Supplement 10), which is considered to be a keystone species in the North Atlantic (Fort et al 2012, Frederiksen et al 2013.…”

Improved transport estimate of the East Icelandic Current 2002–2012

“…40% of the runoff from Iceland [ Jónsdóttir , ]. The average salinity of the upper 170 m was around 34.8, reflecting the “Atlantic” conditions with warmer and more saline water prevailing north of Iceland since the late 1990s [ Valdimarsson et al ., ]. More saline AW (S > 34.93) was encountered in some years (2003, 2004, and 2009–2012; see bars in Figure d).…”

“…to 34.93) of mainly ASW from the Iceland Sea was on average 3.4 ± 0.3 mSv between 2002 and 2012. It was higher in 2002 associated with anomalously low salinity because of more Arctic conditions in the Iceland Sea prevailing in that year [ Valdimarsson et al ., ], and in 2005–early 2006 (exceeding 5 mSv) due to sea ice and particularly due to a stronger current. After 2006, a reduced freshwater transport was related to weaker wind stress and an increased inflow of more saline AW into the Iceland Sea.…”

Anthropogenic flank attack on polar bears: interacting consequences of climate warming and pollutant exposure

“…Dietary shift toward feeding on plants, berries and caribou (Rangifer tarandus) and seabird eggs, respectively (Ramsay and Hobson, 1991;Gormezano and Rockwell, 2013a,b;Iles et al, 2013;Iverson et al, 2014), will most likely decrease and increase, respectively, the dietary uptake of POPs. Furthermore, climate warming induced immigrating warm-adapted fish species (Valdimarsson et al, 2012;Mackenzie et al, 2014) may act as biovectors that increases contaminant levels in marine arctic ecosystems (Macdonald et al, 2005;Carrie et al, 2010), ultimately causing increased bioaccumulation of these compounds in polar bears.…”