The effect of global climate change on the future distribution of economically important macroalgae (seaweeds) in the northwest Atlantic

Amina H Khan,Elisabeth Levac,Gerhard Pohle,Gail L Chmura,Lou Van Guelphen,Daniel E Schindler

doi:10.1139/facets-2017-0091

Amina H Khan, Elisabeth Levac + Show 4 more

Open Access

https://doi.org/10.1139/facets-2017-0091

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Abstract

An increase in greenhouse gas emissions has led to a rise in average global air and ocean temperatures. Increased sea surface temperatures can cause changes in species’ distributions, particularly those species close to their thermal tolerance limits. We use a bioclimate envelope approach to assess potential shifts in the range of marine macroalgae harvested in North American waters: rockweed ( Fucus vesiculosus Linnaeus, 1753), serrated wrack ( Fucus serratus Linnaeus, 1753), knotted wrack ( Ascophyllum nodosum (Linnaeus) Le Jolis, 1863), carrageen moss ( Chondrus crispus Stackhouse, 1797), and three kelp species ( Laminaria digitata (Hudson) J.V. Lamouroux, 1813; Saccharina latissima (Linnaeus) C.E. Lane, C. Mayes, Druehl et G.W. Saunders, 2006; and Saccharina longicruris (Bachelot de la Pylaie) Kuntze, 1891). We determined species’ thermal limits from the current sea surface temperatures associated with their geographical distributions. Future distributions were based on sea surface temperatures projected for the year ∼2100 by four atmosphere-ocean general circulation models and earth system models for regional concentration pathways (RCPs) 4.5 and 8.5. Future distributions based on RCP 8.5 indicate that the presence of all but rockweed ( F. vesiculosus) is likely to be threatened by warming waters in the Gulf of St. Lawrence and along the Atlantic coast of Nova Scotia. Range retractions of macroalgae will have significant ecological and economic effects including impacts on commercial fisheries and harvest rates and losses of floral and faunal biodiversity and production, and should be considered in the designation of marine protected areas.

Highlights

With unprecedented increases in greenhouse gas emissions and a warming climate, marine ecosystems will incur major changes in ecological structure and function
The present range of S. latissima, S. longicruris, L. digitata, A. nodosum, and F. vesiculosus already extends poleward beyond our study area (Taylor 1957, table 1; Sears 2002)
(S. longicruris, S. latissima, and F. vesiculosus) are found at ∼80°N and there is little coastline left for poleward range expansion in the northwest Atlantic

Summary

Introduction

With unprecedented increases in greenhouse gas emissions and a warming climate, marine ecosystems will incur major changes in ecological structure and function. Species are likely to react in one of three ways: adapting, migrating to more appropriate climate conditions, or becoming extirpated from their original distribution (Walther et al 2002; Parmesan and Yohe 2003; Parmesan 2006). Climate change has already had observable impacts on the distribution of marine species including seaweeds (Perry et al 2010). Poleward range extensions of rockweed (Fucus vesiculosus Linnaeus, 1753) (Jueterbock et al 2013; Nicastro et al 2013), a brown seaweed species Some macroalgae can adapt to warming through northward shifts of their range, it can be at the expense of overall distribution and loss of genetic diversity within a species (Nicastro et al 2013)

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