The effects of warming on the ecophysiology of two co-existing kelp species with contrasting distributions

Hargrave, MS, Foggo, A, Pessarrodona, A and Smale, DA 2017 The effects of warming on the ecophysiology of two co-existing kelp species with contrasting distributions. Oecologia, 183 (2).

Hargrave et al 2016 Oecologia kelp thermal stress_FINAL_accepted version.pdf - Accepted Version

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The northeast Atlantic has warmed significantly since the early 1980s, leading to shifts in species distributions and changes in the structure and functioning of communities and ecosystems. This study investigated the effects of increased temperature on two co-existing habitat-forming kelps: Laminaria digitata, a northern boreal species, and Laminaria ochroleuca, a southern Lusitanian species, to shed light on mechanisms underpinning responses of trailing and leading edge populations to warming. Kelp sporophytes collected from southwest United Kingdom were maintained under 3 treatments: ambient temperature (12 °C), +3 °C (15 °C) and +6 °C (18 °C) for 16 days. At higher temperatures, L. digitata showed a decline in growth rates and Fv/Fm, an increase in chemical defence production and a decrease in palatability. In contrast, L. ochroleuca demonstrated superior growth and photosynthesis at temperatures higher than current ambient levels, and was more heavily grazed. Whilst the observed decreased palatability of L. digitata held at higher temperatures could reduce top-down pressure on marginal populations, field observations of grazer densities suggest that this may be unimportant within the study system. Overall, our study suggests that shifts in trailing edge populations will be primarily driven by ecophysiological responses to high temperatures experienced during current and predicted thermal maxima, and although compensatory mechanisms may reduce top-down pressure on marginal populations, this is unlikely to be important within the current biogeographical context. Better understanding of the mechanisms underpinning climate-driven range shifts is important for habitat-forming species like kelps, which provide organic matter, create biogenic structure and alter environmental conditions for associated communities.

Item Type: Publication - Article
Divisions: Marine Biological Association of the UK > Ocean Biology
Depositing User: Dr Dan Smale
Date made live: 20 Feb 2017 16:03
Last Modified: 09 Feb 2024 16:51

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