This trend is consistent with many other studies that show the ability of micro-phytoplankton to respond rapidly to increased nutrient availability, stimulating their growth rates. Initially, the phytoplankton community was totally dominated by micro-phytoplankton, particularly diatoms however, in the subsequent weeks (up to 48-weeks post flood) the community changed to one of nano- and pico-plankton in all areas of the Bay not usually affected by river flow. Despite the reduced light availability, the phytoplankton community responded rapidly (1–2 weeks) to the nutrients from flood inputs, as measured using pigment concentrations and cell counts and observed in ocean color satellite imagery.
Changes in these parameters together with changes in Colored Dissolved Organic Matter (CDOM) and sediment concentrations significantly reduced the light availability within the water column. Immediately after maximum flood levels were reached on the rivers flowing into the bay, the lowest salinity, and highest turbidity values, in more than a decade, were measured in the Bay and the areal extent of the flood-related parameters was also far greater than previous flood events. This study examined the effects of a 1:100 year summer flood on the phytoplankton community in an Australian subtropical bay – Moreton Bay – over 48 weeks, from January to December 2011. Subtropical systems experience occasional severe floods, dramatically altering the phytoplankton community structure, in response to changes in salinity, nutrients, and light. 11Healthy Land and Water, Brisbane, QLD, Australia.10Australian Rivers Institute, Griffith University, Nathan, QLD, Australia.9CSIRO Oceans and Atmosphere, Acton, Canberra, ACT, Australia.8Climate Change Cluster (C3), University of Technology, Sydney, NSW, Australia.7Instituto do Mar, Federal University of Sao Paulo, Santos, Brazil.6The Water Institute of the Gulf, Baton Rouge, LA, United States.5Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, United States.4School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia.3Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, University of Queensland, St Lucia, QLD, Australia.2CSIRO Oceans and Atmosphere, Brisbane, QLD, Australia.1CSIRO Oceans and Atmosphere, Hobart, TAS, Australia.Burford 10, Emily Saeck 10,11 and Andrew D. D’Sa 5, Luiz Felipe Mendes Gusmão 2,7, Penelope Ajani 8, Thomas Schroeder 2, Phillip W. Rochester 2, Kadija Oubelkheir 2,4, Bingqing Liu 5,6, Eurico J.
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