Sponge assemblages and predicted archetypes in the eastern Canadian Arctic

Abstract

Little information exists on the environmental requirements of sponges from the Canadian Arctic, increasing the necessity to establish baseline distribution data on sponge assemblages to predict their susceptibility to climate change. Here we describe the sponge taxa of Hudson Strait, Ungava Bay, Western Davis Strait and Western Baffin Bay collected by Canadian research vessel trawl surveys. A total of 2026 sponge specimens were examined, and 93 different taxa were identified with 79% identified to species, of which 2 are new to science, 1 recorded for the first time in the North Atlantic, 16 are new records for the northwest Atlantic, and 10 are new records for the Baffin Bay, Davis Strait and Hudson Strait sponge fauna. Taxonomic distinctness was higher north of Cape Dyer and south of Davis Strait, whereas the number of species reached a maximum in Davis Strait, which represents the southern distribution limit of the arctic sponge fauna along the slope in this region. Five sponge species assemblages were identified, some of which have been observed elsewhere, suggesting that they may be common to the North Atlantic and at the generic level to the global oceans. Two of the Baffin Bay−Davis Strait assemblages were characterized by large structure-forming astrophorids: one, with arctic species, found at midwater depths in Baffin Bay and the other, characterized by boreal species, was found deeper, south of Davis Strait. Another assemblage characterized by glass and carnivorous sponges was found along the continental slope of western Baffin Bay. Candidate target indicator species are provided for future sponge community monitoring.

Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic

“…The species composition of deep-sea sponge grounds in the NW Atlantic, from Davis Strait to Flemish Cap (Murillo et al, 2012(Murillo et al, , 2016b(Murillo et al, , 2018, is similar to the boreal sponge grounds described by Klitgaard and Tendal (2004) for the NE Atlantic, while arctic astrophorids are found in southern Baffin Bay (Murillo et al, 2018). Dense aggregations of a globally unique population of the glass sponge Vazella pourtalesii is found on the Scotian Shelf over large spatial scales (Beazley et al, 2018).…”

“…Interestingly, geodiid sponge grounds off the Flemish Cap and Grand Banks have persisted for the last 130 kya (Murillo et al, 2016a), despite large shifts in water mass structure alternating between the warmer Atlantic waters and the cooler Labrador Current. Murillo et al, 2018 further noted that the structureforming Geodia species were found in areas with high primary production and fast currents that would provide the high food supply needed to reach their large biomasses. The importance of current regime and interactions between water masses has also been shown for the Faroe-Shetland Channel deep-sea sponge aggregations (Kazanidis et al, 2019), the Arctic sponge ground on the Schultz Seamount (Arctic Mid-Ocean Ridge; Roberts et al, 2018) and deep-sea aggregations of hexactinellids in the NE Atlantic (Rice et al, 1990;Barthel et al, 1996).…”

“…One of the first reports of these habitats was by Rice et al (1990), who observed dense aggregations (density values ∼1.5 ind•m −2 ) of the hexactinellid Pheronema carpenteri (Figure 2) in the Porcupine Seabight (NE Atlantic). Subsequently, records of sponge grounds came both from the eastern (e.g., Klitgaard and Tendal, 2004;Howell et al, 2016;Roberts et al, 2018;Kazanidis et al, 2019) and western deep North Atlantic (e.g., Murillo et al, 2012Murillo et al, , 2016aMurillo et al, , 2018Knudby et al, 2013;Kenchington et al, 2014;Beazley et al, 2018). These included records not only of hexactinellids, but also of demosponges and especially those from the family Geodidae (Order Astrophorida, commonly known as ostur; Figure 2).…”

Seafloor biodiversity of Canada's three oceans: Patterns, hotspots and potential drivers

“…Further, ongoing efforts to sample and identify marine invertebrates in Canadian waters have already increased the total number of taxa reported here (e.g. Arctic sponges: Murillo et al, ).…”

Geographic range extensions of stalked, flabelliform sponges (Porifera) from eastern Canada with a new combination of a species of Plicatellopsis in the North Atlantic

“…Axinella arctica (Vosmaer, 1885) is found on rocky bottoms attached to hard substrates. In the North Labrador Sea and Baffin Bay the species was collected in deep water > 412 m. The species was also collected in the North Labrador Sea by Murillo et al (2018), and reported from the Barents Sea, Nordic Seas, and European Waters (Stephens 1921;Van Soest et al 2000. This species has a more northern distribution and was not collected in the Gulf of St. Lawrence.…”