Torres Strait Seagrass 2020 Report Card

Seagrass is a critical habitat in Torres Strait. Extensive seagrass meadows support populations of dugong, green turtle, and fishery species. Strong cultural and spiritual links exist between Torres Strait Island communities and these species and environments. The Torres Strait Seagrass Monitoring Program (TSSMP) is a network of seagrass monitoring programs that regularly assess the condition of this key habitat. The TSSMP incorporates the Torres Strait Seagrass Observers Program, Ranger Subtidal Monitoring Program, Queensland Ports Seagrass Monitoring Program, and Reef-top Monitoring Program. Data from these programs is used to produce this report. Seagrass condition assessments in this report card use data collected mid-2019 to mid-2020 by the TSSMP. Seagrass condition is graded from A (very good) to E (very poor) relative to baseline conditions, and scored on a 0–1 scale. Eighteen sites/meadows were classified for the 2020 report card across the Western, Eastern and Central Island Clusters. No results are presented for the Inner Cluster in the 2020 report card as monitoring was postponed due to COVID-19 travel restrictions. In the Western and Eastern Clusters seagrass condition declined from good to satisfactory in the past year, mostly because of decreases in seagrass abundance (biomass/percent cover). Declines were particularly dramatic in the Orman Reefs-Mabuyag Island region. In the Central Cluster overall condition remained good despite small declines in seagrass abundance. Of the sites/meadows with overall condition scores, half were in good condition or very good condition, three were in satisfactory condition, two were in poor condition, and one was in very poor condition. Several important milestones were reached in the monitoring program in 2020. First, 10-years of monitoring data was reached at Mua Island (MU1) and Mer Island (MR1 and MR2), meaning that the baselines for these locations are now set. Second, 5-years of monitoring data was reached at Dungeness Reef intertidal and Orman Reefs subtidal, meaning we have some confidence around preliminary baseline conditions and overall grades and scores are included in the report card for the first time. This annual report card will continue to improve as more sites/meadows build toward 10 years of baseline information. This report card highlights areas where information is lacking and suggests a pathway for better understanding seagrass dynamics, and improving representativeness and reliability of condition scores for seagrass in Torres Strait Island Clusters. We recommend: (1) testing of seagrass samples for disease/pathogens to determine if this is the cause of seagrass declines, (2) commencing regular turtle and dugong surveys and herbivore exclusion experiments to better understand seagrass-herbivore interactions, (3) establishing monitoring in the Top-Western Cluster where no monitoring currently occurs, (4) expanding meadow-scale and subtidal block monitoring to include examples in all island clusters, and (5) establishing additional intertidal monitoring locations in the Central and Eastern Clusters. These additions would vastly improve our annual assessment of seagrass condition in the region