Population structure of Mytilus edulis in the intertidal zone in a sub-Arctic fjord, SW Greenland

Abstract

The blue mussel Mytilus edulis is widely distributed and acknowledged for its ecological importance in the intertidal zone in northern temperate areas. However, detailed studies of the structure and dynamics of intertidal M. edulis populations are lacking in its northern distribution area. This study provides baseline information on the population structure of M. edulis in the mid-intertidal zone of the sub-arctic Godthåbsfjord in West Greenland (64°N). Abundance was very patchy (average 18.6 ind. 0.049 m −2 ; range 0 to 312) and concentrated around crevices, boulders and macroalgae beds. Average biomass was 7.78 g wet mass 0.049 m −2 . Young specimens < 3 yr old (or <15 mm shell length) made up 82% of the population. Maximum age was estimated at 19 yr. The age structure suggested that the annual instantaneous mortality rate, Z, gradually decreased with age from 0.82 to 0.12. Growth functions obtained from size-at-age data showed significant differences between sampling sites in the Godthåbsfjord, overall covering much of the geographical variation found in the North Atlantic. The absence of invertebrate predators in the intertidal in this sub-Arctic habitat suggests that physical drivers are important for structuring the M. edulis community. Winter temperatures below −15°C combined with ice scouring are suggested to be the key drivers. Crevices, boulders and macroalgae beds are important refuges during detrimental extreme events but also provide variable growth conditions.

Rising air temperatures will increase intertidal mussel abundance in the Arctic

“…Abundance data from 15 sites around Nuuk (collected in June 2011) were obtained from Blicher et al (2013). We further collected animals at 12 sites on Disko Island (August 2012), 18 sites around Uummannaq (July 2012), 13 sites around Upernavik (July 2013) and 15 sites around Qaanaaq (August 2014) (Fig.…”

“…temperature and sea ice. Because local topography over the scale of centimeters can affect the abundance and biomass of intertidal mussels by order of magnitudes (Kostylev & Erlandsson 2001, Blicher et al 2013), a sampling regime was designed specifically to capture this variation, thus allowing mussel collection in similar and comparable habitats at each sampling site. To ensure similar sites were sampled, the overall physical environment (ice scour, rugosity and orientation) was assessed visually at each site (detailed results on all environmental parameters are in Supplement 2).…”

“…pdf), ocean and air temperatures and length of the period with primary production (Sejr et al 2009, Krause-Jensen et al 2012. Because only few quantitative studies have been conducted in this intertidal zone (Hansen 1999, Blicher et al 2013, Høgslund et al 2014, preliminary research should focus on foundation species because of their importance for ecosystems. Foundation species include shell-forming molluscs as they create hard substrates increasing the abundance of a diverse associated fauna (Gutiérrez et al 2011, Thyrring et al 2015b.…”

A first report on coexistence and hybridization of Mytilus trossulus and M. edulis mussels in Greenland

“…In the mid-intertidal zone, blue mussel beds are found to dominate at wave-exposed steep sites. Such beds are highly productive, and besides being the primary food source for birds, fish and invertebrates, they provide habitat and refuge for numerous organisms (Blicher et al 2013). Further, Mytilus has been used extensively in environmental monitoring studies, for example around mining-related activities to monitor for element dispersal (e.g., Riget et al 1997Riget et al , 2000Søndergaard 2013;Sønder-gaard et al 2014;Bach et al 2014).…”

“…Mytilus edulis is important in the coastal areas in Greenland and has been applied in a range of ecology studies (e.g., Theisen 1973;Strand and Asmund 2003;Wanamaker et al 2007;Blicher et al 2013;Høgslund et al 2014;Thyrring et al 2015). In the mid-intertidal zone, blue mussel beds are found to dominate at wave-exposed steep sites.…”