Population dynamics of temperate kelp forests near their low-latitude limit

Pereira, Tânia R.; Engelen, Aschwin; Pearson, Gareth; Valero, Myriam; Serrao, Ester

http://hdl.handle.net/10400.1/13191

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Authors

Valero, Myriam

Abstract(s)

Climate change tends to shift species ranges polewards. Demographic processes at the rear edge are particularly interesting yet poorly understood. This study aimed to provide insights in population dynamics and resilience of temperate kelp populations at their shallower and lower latitude distribution limits, in northern Portugal. Intertidal populations of the perennial Laminaria ochroleuca, Laminaria hyperborea and the annual Saccorhiza polyschides were censused for two years and projection matrix models used to assess their demographic state and the most important demographic processes for their maintenance and growth. Furthermore, during the second year of census, the northern Portuguese coast was impacted by a late winter storm that caused extensive damage to these communities, allowing an assessment of their resilience. Yearly climate variations may affect the recruitment timing of S. polyschides, preventing sporophytes from reaching maturity, thus impairing spore production, rendering the population entirely dependent on the survival of microscopic forms. Year-round spore production by L. ochroleuca is advantageous, as it is less likely impaired by occasional extreme events. Still, while recovery of L ochroleuca took longer than two years. S. polyschides, was able to recover the following year. If future recurrence and duration of such highly energetic storms increases with climate change; these populations are expected to become gradually younger, providing less canopy. In contrast, no recovery of L hyperborea was observed. Lack of reproductive success, limited dispersal from neighboring populations and abiotic factors might have contributed to the impaired repopulation. Species persistence follows its strategy, with opportunistic species revealing higher resilience. (C) 2017 Elsevier B.V. All rights reserved.

Keywords

Macroalgal spore dispersal Intertidal rock pools Large brown seaweeds Laminaria-ochroleuca Macrocystis-pyrifera Southern-california Giant-kelp El-Nino Coastal environments Microscopic stages