title: Effects of elevated temperature and CO2 on intertidal microphytobenthos.
abstract: BACKGROUND
  Microphytobenthos (MPB) are the main primary producers of many intertidal and shallow subtidal environments. Although these coastal ecosystems are particularly vulnerable to anthropogenic activities, little is known on the effects of climate change variables on the structure and productivity of MPB communities. In this study, the effects of elevated temperature and CO2 on intertidal MPB biomass, species composition and photosynthetic performance were studied using a flow-through experimental life support system.
  
  
  RESULTS
  Elevated temperature had a detrimental effect on MPB biomass and photosynthetic performance under both control and elevated CO2. Furthermore, elevated temperature led to an increase of cyanobacteria and a change in the relative abundance of major benthic diatom species present in the MPB community. The most abundant motile epipelic species Navicula spartinetensis and Gyrosigma acuminatum were in part replaced by tychoplanktonic species (Minidiscus chilensis and Thalassiosira cf. pseudonana) and the motile epipelic Nitzschia cf. aequorea and N. cf. aurariae. Elevated CO2 had a beneficial effect on MPB biomass, but only at the lower temperature. It is possible that elevated CO2 alleviated local depletion of dissolved inorganic carbon resulting from high cell abundance at the sediment photic layer. No significant effect of elevated CO2 was detected on the relative abundance of major groups of microalgae and benthic diatom species.
  
  
  CONCLUSIONS
  The interactive effects of elevated temperature and CO2 may have an overall detrimental impact on the structure and productivity of intertidal MPB, and eventually in related ecosystem services.
authors.affiliation: Department of Biology, Marine Biological Section, University of Copenhagen, Strandpromenaden 5, DK-3000, Helsingør, Denmark. Paulo.Cartaxana@bio.ku.dk.
authors.forename: Paulo
authors.initials: P
authors.lastname: Cartaxana
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal. scvieira@fc.ul.pt.|Centro de Biodiversidade, Genómica Integrativa e Funcional (BioFIG), Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal. scvieira@fc.ul.pt.
authors.forename: Sónia
authors.initials: S
authors.lastname: Vieira
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal. lourencosribeiro@gmail.com.
authors.forename: Lourenço
authors.initials: L
authors.lastname: Ribeiro
authors.affiliation: Departamento de Biologia & CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal. ruimirandarocha@ua.pt.
authors.forename: Rui J M
authors.initials: RJ
authors.lastname: Rocha
authors.affiliation: Departamento de Biologia & CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal. sonia.cruz@ua.pt.
authors.forename: Sónia
authors.initials: S
authors.lastname: Cruz
authors.affiliation: Departamento de Biologia & CESAM - Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal. rjcalado@ua.pt.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Calado
authors.affiliation: Centro de Biodiversidade, Genómica Integrativa e Funcional (BioFIG), Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal. jmlsilva@fc.ul.pt.
authors.forename: Jorge Marques
authors.initials: JM
authors.lastname: da Silva
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000032:analysis*; D057231:Climate Change; D000458:Cyanobacteria / Q000502:physiology; D017377:Diatoms / Q000502:physiology*; D017753:Ecosystem; D019015:Geologic Sediments; D008386:Marine Biology; D010788:Photosynthesis; D013696:Temperature
chemical_list: D002245:Carbon Dioxide