Short Presentation (chance to upgrade) Australian Marine Sciences Association 2026 Conference

What is their fate? A comparison of beach washup mortalities with observed change to fish communities using BRUVS  (140224)

Craig A Meakin 1 , Danny Brock 1 , Sophie Russell 1 , Dan Easton 1 , Sasha Whitmarsh 1 2 , Tess Shrestha 1 , James Whitelaw 1 , Aude Loisier 1 , Lauren Casey 1 , Chloe Roberts 3 , Charlie Huveneers 3 , Simon Bryars 1 , Janine Baker 4
  1. Department for Environment and Water, Government of South Australia, Adelaide, SA, Australia
  2. School of life and environmental sciences, Deakin University, Warnanbool, Victoria, Australia
  3. College of Science and Engineering , Flinders University, Adelaide, SA, Australia
  4. Independent consultat, Adelaide, SA

The onset of the Harmful algal bloom (HAB) in March 2025 was quickly followed by the establishment of an iNaturalist project to document the thousands of mortalities washing up on beaches. This project provided crucial information on a wide range of species. The South Australian Department for Environment and Water has conducted Baited Remote Underwater Video Surveys (BRUVS) for over a decade and following the HAB, embarked on a statewide resurvey of historic BRUVS sites to document any changes in species assemblages as part of the HAB impact assessment on nearshore marine biodiversity project. The complementary monitoring provides a unique opportunity to see how beach washups correlate to changes observed on BRUVS footage.  

Beach washups detect a much higher diversity of species than BRUVS, however BRUVS observations can allow for a quantitative assessment about the scale of impact to local fish communities. Furthermore, some species may be influenced by the HAB but be less susceptible to washing up (i.e. southern calamari) and BRUVS can be used to assess changes that aren’t immediately obvious from beach mortalities.    

This presentation will highlight some of the most commonly observed species from both methods and provides quantitative information on the scale of impact from historic and HAB BRUVS observations.