Torres Strait Seagrass 2021 Report Card

Carter, Alexandra, David, Madeina, Whap, Terrence, Hoffman, Luke, Scott, Abigail, and Rasheed, Michael (2021) Torres Strait Seagrass 2021 Report Card. Report. James Cook University, Cairns, QLD, Australia.

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Abstract

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) incorporates an extensive 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 are integrated and used to produce this report on seagrass condition.

Twenty-six sites/meadows were classified for the 2021 report card across the Western, Central and Inner Island Clusters. No monitoring occurred in the Eastern Cluster in 2021.

Overall, seagrasses in the Inner Cluster were in a good condition and in a satisfactory condition in the Central and Western Clusters.

Within these Clusters there were individual sites and types of meadows where seagrass condition is of substantial concern, including: a. Subtidal meadows across the Western and Central Clusters where large scale declines in biomass and loss of the key subtidal species Halophila spinulosa first noted in 2020 had continued in 2021. b. Condition of intertidal meadows around Mabuyag Island and the Orman Reefs in the Western Cluster continued to be well-below average. c. An individual monitoring site at Poruma Island where cover and species experienced a large decline due to localised sand movement.

Investigations are ongoing into the potential causes of the declines in subtidal seagrass throughout the Western and Central Clusters and intertidal seagrasses in the Western Cluster, including the role of herbivory, potential for seagrass disease, and environmental conditions that may be contributing to sediment movement and light.

Several important milestones were reached in the monitoring program in 2021: a. Meadow-scale monitoring commenced at Masig Island, filling a critical information gap in the Central Cluster (Map 3). b. Several sites reached 10-years of monitoring data, meaning that the baselines for these locations are now set. c. 5-years of monitoring data were achieved at Orman Reefs intertidal (Kai and Gariar Reefs) and Poruma Island (PM1 and PM2), allowing preliminary baseline conditions and overall grades and scores to be included in the report card for the first time.

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) establishing monitoring in the Top-Western Cluster, (2) expanding subtidal monitoring, (3) expanding meadow-scale monitoring in the Eastern Cluster, (4) establishing a comprehensive testing program for seagrass disease, and (5) adding local weather/wind and benthic light stations in areas of concern. These additions would vastly improve our annual assessment of seagrass condition and drivers of observed changes in the region.

Item ID: 70797
Item Type: Report (Report)
Keywords: Seagrass, Torres Strait, report card, monitoring
Copyright Information: © James Cook University, 2021.
Funders: Torres Strait Regional Authority (TSRA)
Date Deposited: 11 Nov 2021 02:41
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410402 Environmental assessment and monitoring @ 100%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180501 Assessment and management of benthic marine ecosystems @ 100%
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