Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios.

Wirtz, Kai W. and Sommer, Ulrich (2013) Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios. Marine Biology, 160 (9). pp. 2503-2516. DOI 10.1007/s00227-013-2271-z.

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Abstract

Driving factors of phytoplankton spring blooms have been discussed since long, but rarely analyzed quantitatively. Here, we use a mechanistic size-based ecosystem model to reconstruct observations made during the Kiel mesocosm experiments (2005–2006). The model accurately hindcasts highly variable bloom developments including community shifts in cell size. Under low light, phytoplankton dynamics was mostly controlled by selective mesozooplankton grazing. Selective grazing also explains initial dominance of large diatoms under high light conditions. All blooms were mainly terminated by aggregation and sedimentation. Allometries in nutrient uptake capabilities led to a delayed, post-bloom dominance of small species. In general, biomass and trait dynamics revealed many mutual dependencies, while growth factors decoupled from the respective selective forces. A size shift induced by one factor often changed the growth dependency on other factors. Within climate change scenarios, these indirect effects produced large sensitivities of ecosystem fluxes to the size distribution of winter phytoplankton. These sensitivities exceeded those found for changes in vertical mixing, whereas temperature changes only had minimal impacts.

Document Type: Article
Additional Information: WOS:000323622400020
Keywords: Phytoplankton; Kiel mesocosm experiments
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-N Experimental Ecology - Food Webs
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00227-013-2271-z
ISSN: 0025-3162
Projects: PACES, AQUASHIFT, Future Ocean
Date Deposited: 12 Aug 2013 09:55
Last Modified: 29 Jun 2018 09:22
URI: http://oceanrep.geomar.de/id/eprint/21913

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