MEPS 589:59-72 (2018)  -  DOI:

Response to experimental warming in northern eelgrass populations: comparison across a range of temperature adaptations

P. Beca-Carretero1,2,*, B. Olesen3, N. Marbà1, D. Krause-Jensen4,5

1Department of Global Change Research, IMEDEA (CSIC-UIB), Institut Mediterrani d’Estudis Avancats, Miquel Marques 21, 07190 Esporles (Illes Balears), Spain
2Botany and Plant Science, School of Natural Sciences, and Ryan Institute, National University of Ireland Galway, University Road, Galway H91 TK33, Ireland
3Department of Bioscience, Aarhus University, Ole Worms Allé 1, Building 1135, 8000 Aarhus C, Denmark
4Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark
5Arctic Research Centre, Aarhus University, Ny Munkegade 114, Building 1540, 8000 Aarhus C, Denmark
*Corresponding author:

ABSTRACT: Global warming may exert diverging effects on eelgrass (Zostera marina L.) populations originating from the northern versus the central part of the distribution range and on populations growing at saturating versus limiting light. We experimentally examined growth and physiological temperature responses of 3 eelgrass populations adapted to different temperature regimes in subarctic Greenland (2 populations) and in Denmark (1 population). Shoots were incubated at 5 different temperatures (10, 15, 20, 25 and 28°C) for 15 to 16 d at a saturating irradiance (200 µmol m-2 s-1) and one of the populations was also incubated at a limited irradiance of 50 µmol m-2 s-1. All populations exhibited optimum temperatures of 20 to 25°C for photosynthesis and growth under saturating light, while light limitation reduced the optimum by 5 to 10°C. When compared at their respective in situ summer temperature (i.e. 10, 15 and 20°C), all populations exhibited similar relative growth rates, indicating a capacity for local adaptation. The 2 subarctic populations exhibited higher activation energy for growth and, hence, greater responsiveness to warming than the centrally located population. However, subarctic populations were also more sensitive to extreme high temperatures, showing faster increases in respiration rates and declines in photosynthesis. Sensitivity to warming varied across light conditions with light-limited plants being most vulnerable to extreme temperatures, causing a negative carbon budget. In conclusion, projected warming would stimulate the performance of subarctic eelgrass populations but could eventually compromise populations in the center of the distribution range, which currently grow close to their temperature optimum.

KEY WORDS: Experimental warming · Latitude comparison · Production · Energy activation · Photosynthetic response · Greenland · Denmark · Seagrass · Zostera marina

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Cite this article as: Beca-Carretero P, Olesen B, Marbà N, Krause-Jensen D (2018) Response to experimental warming in northern eelgrass populations: comparison across a range of temperature adaptations. Mar Ecol Prog Ser 589:59-72.

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