Connecting targets for catchment sediment loads to ecological outcomes for seagrass using multiple lines of evidence

Victoria Lambert; Zoe T Bainbridge; Catherine Collier; Stephen E Lewis; Matthew P Adams; Alex Carter; Megan I Saunders; Jon Brodie; Ryan D R Turner; Michael A Rasheed; Katherine R O'Brien

doi:10.1016/j.marpolbul.2021.112494

Connecting targets for catchment sediment loads to ecological outcomes for seagrass using multiple lines of evidence

Mar Pollut Bull. 2021 Aug:169:112494. doi: 10.1016/j.marpolbul.2021.112494. Epub 2021 May 26.

Affiliations

¹ School of Chemical Engineering, The University of Queensland, St Lucia, QLD, Australia.
² TropWATER, James Cook University, Townsville, QLD, Australia.
³ School of Chemical Engineering, The University of Queensland, St Lucia, QLD, Australia; School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, Australia; ARC Centre of Excellence for Mathematical and Statistical Frontiers, Queensland University of Technology, Brisbane, QLD, Australia; Centre for Data Science, Queensland University of Technology, Brisbane, QLD, Australia.
⁴ CSIRO Oceans and Atmosphere, Brisbane, QLD, Australia.
⁵ ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia.
⁶ Water Quality & Investigations, Department of Environment and Science, Queensland Government, Dutton Park, QLD, Australia; Managing for Resilient Landscapes, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD, Australia.
⁷ School of Chemical Engineering, The University of Queensland, St Lucia, QLD, Australia. Electronic address: k.obrien@uq.edu.au.

PMID: 34051518
DOI: 10.1016/j.marpolbul.2021.112494

Abstract

Catchment impacts on downstream ecosystems are difficult to quantify, but important for setting management targets. Here we compared 12 years of monitoring data of seagrass area and biomass in Cleveland Bay, northeast Australia, with discharge and associated sediment loads from nearby rivers. Seagrass biomass and area exhibited different trajectories in response to river inputs. River discharge was a slightly better predictor of seagrass indicators than total suspended solid (TSS) loads, indicating that catchment effects on seagrass are not restricted to sediment. Linear relationships between Burdekin River TSS loads delivered over 1-4 years and seagrass condition in Cleveland Bay generated Ecologically Relevant Targets (ERT) for catchment sediment inputs. Our predicted ERTs were comparable to those previously estimated using mechanistic models. This study highlights the challenges of linking catchment inputs to condition of downstream ecosystems, and the importance of integrating a variety of metrics and approaches to increase confidence in ERTs.

Keywords: Catchment sediment; Ecologically relevant targets; Marine ecosystems; Seagrass.

MeSH terms

Australia
Ecosystem*
Environmental Monitoring
Geologic Sediments*
Rivers