Novel observations of capelin (Mallotus villosus) spawning directly on a brown algae species (Desmarestia viridis) in coastal Newfoundland, Canada

Abstract

Capelin (<em>Mallotus villosus</em>) is a key forage fish species within its circumpolar range. This species’ importance lies in its role in the typical marine ‘wasp-waist’ food web, where capelin acts as a conduit for energy flow from lower to higher trophic levels. Herein we describe a novel observation of capelin spawning subtidally on an annual brown algae species, <em>Desmarestia viridis</em>, during July–August 2019 in Placentia Bay, Newfoundland, Canada. Based on extensive video surveys of the seabed along with shoreline surveys and sediment sampling, we did not find other nearby sites with typical capelin subtidal and intertidal spawning habitat (i.e. medium sand to pebble gravel). Findings suggest that capelin spawned directly on this brown algae species, <em>D. viridis</em>. Eggs adhered to <em>D. viridis</em> developed normally and hatched successfully. As temperatures of intertidal areas are predicted to increase above temperatures suitable for capelin egg rearing (2–12°C) with climate change, <em>D. viridis</em> may become a high-quality subtidal spawning habitat for capelin and other fish species. In support, this algal species is adapted to colonize high disturbance areas, allowing protection from egg predators in a high flow environment while also being resistant to urchin grazing.