Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic
Franke, K.; Liesner, D.; Heesch, S.; Bartsch, I. (2021). Looks can be deceiving: contrasting temperature characteristics of two morphologically similar kelp species co-occurring in the Arctic. Bot. Mar. 64(3): 163-175. https://dx.doi.org/10.1515/bot-2021-0014
In: Botanica Marina. Walter de Gruyter & Co: Berlin; New York. ISSN 0006-8055; e-ISSN 1437-4323, more
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C:N-ratio; gametogenesis; growth rate; PAM fluorometry; sporophyte |
| Authors | | Top |
- Franke, K.
- Liesner, D.
- Heesch, S.
- Bartsch, I.
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| Abstract |
Two morphologically similar digitate kelp species, Laminaria digitata and Hedophyllum nigripes, co-occur along a shallow sublittoral depth gradient in the Arctic but, in contrast to L. digitata, very few ecophysiological data exist for H. nigripes. We investigated growth, survival, photosynthetic characteristics and carbon:nitrogen ratios of juvenile sporophytes, and recruitment and survival of gametophytes in genetically verified Arctic isolates of both species along temperature gradients (0–25 °C) over 14 days. Laminaria digitata gametophytes survived 23–24 °C, while sporophytes survived 21–22 °C. Hedophyllum nigripes had lower temperature affinities. Gametophytes survived 19–21 °C, while sporophytes survived 18 °C. Male gametophytes were more heat-tolerant than female gametophytes in both species. The pronounced cold adaption of H. nigripes compared to L. digitata also became apparent in different sporophyte growth optima (L. digitata: 15 °C; H. nigripes: 10 °C) and gametogenesis optima (L. digitata: 5–15 °C; H. nigripes: 0–10 °C). Higher carbon:nitrogen ratios in H. nigripes suggest an adaptation to nutrient poor Arctic conditions. The overall temperature performance of H. nigripes possibly restricts the species to Arctic–Sub-Arctic regions, while Arctic L. digitata behaved similarly to cold-temperate populations. Our data suggest that a future increase in seawater temperatures may hamper the success of H. nigripes and favour L. digitata in Arctic environments. |
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