Ms Bianca Reis1, Mr João Nuno Franco2, Mr Hugo Sainz Meyer1, Mr Oscar Babé Gómez1, Ms Friederike Peiffer3, Mrs Isabel Sousa-Pinto1, Mr Francisco Arenas1
1CIIMAR – University Of Porto, Porto, Portugal, 2MARE-Instituto Politécnico de Leiria, Peniche, Portugal, 3University of Lisbon, Lisbon, Portugal
This study is suported by the Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal and by INTERREG 3DPARE – EAPA_174/2016
In order to understand climate change impacts on benthic habitats it is crucial to acknowledge its actual ecosystem functioning value. One pertinent way of doing that is through measuring its primary productivity. Quantifying primary productivity can also be a way of evaluating if conservation measures, for example artificial reefs’ implementation, are being efficient and promoting healthy ecosystem functioning.
Accurately quantifying primary productivity in the northeast Atlantic subtidal turbulent rocky bottom habitats is by itself challenging, therefore information is scarce. Kelp primary productivity has been mostly assessed through the quantification of carbon standing stock and biomass, which only provides very rough values of net primary production; ex-situ incubations in the laboratory, in which the obtained values are not capable of represent the real production of an entire community; or in-situ incubations on individual kelp fronds, once again neglecting the community effects on the production. As concerning artificial reefs, quantifying primary productivity as part of monitoring programs to investigate the success of its implementation has never been performed.
Here we describe a novel methodology to assess primary productivity of entire benthic communities in-situ within case studies (kelp reefs vs. turf reefs vs. artificial reefs) in the coast of Portugal using incubation chambers in which the total oxygen flux, temperature, and photo-synthetically active radiation (PAR) were simultaneously recorded. From those measures, net community production and community respiration for a given biomass and water volume was derived from the area enclosed by each chamber. These were flexible, allowing wave motion and at the same time sealed to the benthos minimizing water exchanges.
Results show that this is a good option and feasible methodology to obtain reliable in situ net primary productivity values both in artificial reefs and kelp forest habitats.
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