Climate‐driven substitution of foundation species causes breakdown of a facilitation cascade with potential implications for higher trophic levels. (10th June 2022)

• Record Type: Journal Article
• Authors: Smale, Dan A.; Teagle, Harry; Hawkins, Stephen J.; Jenkins, Helen L.; Frontier, Nadia; Wilding, Cat; King, Nathan; Jackson‐Bué, Mathilde; Moore, Pippa J.
• Is Part Of: Journal of ecology. Volume 110:Number 9(2022)
• Page Start: 2132
• Page End: 2144
• Publication Date: 2022-06-10
• Subjects: climate change -- macroalgae -- species interactions -- temperate reefs -- warming; Plant ecology -- Periodicals; 577.05
• DOI: 10.1111/1365-2745.13936
• Languages: English
• ISSNs: 0022-0477

Abstract

Abstract: Climate change can alter ecological communities both directly, by driving shifts in species distributions and abundances, and indirectly by influencing the strength and direction of species interactions. Within benthic marine ecosystems, foundation species such as canopy‐forming macro‐algae often underpin important cascades of facilitative interactions. We examined the wider impacts of climate‐driven shifts in the relative abundances of foundation species within a temperate reef system, with particular focus on a habitat cascade whereby kelp facilitate epiphytic algae that, in turn, facilitate mobile invertebrates. Specifically, we tested whether the warm‐water kelp Laminaria ochroleuca, which has proliferated in response to recent warming trends, facilitated a secondary habitat‐former (epiphytic algae on stipes) and associated mobile invertebrates, to the same degree as the cold‐water kelp Laminaria hyperborea . The facilitative interaction between kelp and stipe‐associated epiphytic algae was dramatically weaker for the warm‐water foundation species, leading to breakdown of a habitat cascade and impoverished associated faunal assemblages. On average, the warm‐water kelp supported >250 times less epiphytic algae (by biomass) and >50 times fewer mobile invertebrates (by abundance) than the cold‐water kelp. Moreover, by comparing regions of pre‐ and post‐range expansion by L. ochroleuca, we found that warming‐impacted kelp forests supported around half the biomass of epiphytic algae and one‐fifth of the abundance of mobile invertebrates, per unit area, compared with unimpacted forests. We suggest that disruption to this facilitation cascade has the potential to impact upon higher trophic levels, specifically kelp forest fishes, through lower prey availability. Synthesis . Climate‐driven shifts in species' distributions and the relative abundances of foundation organisms will restructure communities and alter ecological interactions, with consequences for ecosystem functioning. We show that climate‐driven substitutions of seemingly similar foundation species can alter local biodiversity and trophic processes in temperate marine ecosystems. Abstract : The cold‐water kelp Laminaria hyperborea supports diverse and abundant stipe assemblages, which represent an important link to higher trophic levels. Climate‐driven substitution of a warm‐adapted kelp Laminaria ochroleuca resulted in the breakdown of a facilitative habitat cascade, leading to lower biodiversity and faunal abundance, with potential implications for higher trophic levels.