Large variations in eutrophication among estuaries reflect massive differences in composition and biomass of macroalgal drift

Ian C Potter; Thomas H Rose; John M Huisman; Norman G Hall; Ainslie Denham; James R Tweedley

doi:10.1016/j.marpolbul.2021.112330

Large variations in eutrophication among estuaries reflect massive differences in composition and biomass of macroalgal drift

Mar Pollut Bull. 2021 Jun:167:112330. doi: 10.1016/j.marpolbul.2021.112330. Epub 2021 Apr 28.

Authors

Ian C Potter¹, Thomas H Rose², John M Huisman³, Norman G Hall¹, Ainslie Denham⁴, James R Tweedley⁵

Affiliations

¹ Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, 90 South St, Murdoch 6150, Western Australia, Australia; Department of Primary Industries and Regional Development, Post Office Box 20, North Beach 6920, Western Australia, Australia.
² Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, 90 South St, Murdoch 6150, Western Australia, Australia; Ecoscope-epc, 20 Carlisle Street, Shoalwater 6169, Western Australia, Australia.
³ Western Australian Herbarium, Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Locked Bag 104, Bentley Delivery Centre, 6983, Western Australia, Australia.
⁴ Department of Primary Industries and Regional Development, Post Office Box 20, North Beach 6920, Western Australia, Australia.
⁵ Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, 90 South St, Murdoch 6150, Western Australia, Australia; Environmental and Conservation Sciences, College of Science, Health, Engineering & Education, Murdoch University, South Street, Murdoch 6150, Western Australia, Australia. Electronic address: j.tweedley@murdoch.edu.au.

PMID: 33932640
DOI: 10.1016/j.marpolbul.2021.112330

Abstract

The characteristics of detached macroalgae (drift) in nearby highly eutrophic and mesotrophic estuaries in south-western Australia are compared to elucidate the magnitude and types of changes that occur in macroalgal drift when estuaries receive excessive nutrient input. Drift characteristics in the large basins of the microtidal, eutrophic Peel-Harvey and mesotrophic Swan-Canning, which is not subjected to large nutrient inputs directly from agricultural land, differed markedly. Biomass (dry weight) in mesotrophic estuary was dominated by rhodophytes (92%), particularly Laurencia and Hypnea, and in eutrophic estuary by opportunistic chlorophytes (68%), especially Chaetomorpha and Ulva. Prevalence and biomass of drift were far greater in the eutrophic estuary, particularly during summer and autumn when macroalgal growth rose sharply. Macroalgal biomass in the eutrophic estuary was positively related to salinity. These results facilitate predictions of how climatic and other anthropogenic changes influence extent of macroalgal growth and thus change the estuarine environment.

Keywords: Microtidal estuaries; Opportunistic chlorophytes; Prevalence; Salinity; Seasonal growth; South-western Australia.

MeSH terms

Biomass
Estuaries*
Eutrophication*
South Australia
Western Australia