Development of seagrass indicators for the Gladstone Healthy Harbour Partnership report card

Carter, Alex, Jarvis, Jessie, Bryant, Catherine, and Rasheed, Michael (2015) Development of seagrass indicators for the Gladstone Healthy Harbour Partnership report card. Report. James Cook University, Cairns, QLD, Australia.

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Executive Summary: The Seagrass Ecology Group within the Centre for Tropical Water and Aquatic Ecosystem Research at James Cook University (TropWATER) have developed an approach for reporting on the condition of seagrasses in the Gladstone Harbour region for incorporation into the Gladstone Healthy Harbour Partnership (GHHP) 2015 report card. Annual long-term monitoring data collected since 2002 at 14 representative seagrass meadows were used to assess the status of three seagrass indicators (mean above-ground biomass, total meadow area and species composition) relative to baseline conditions at each meadow. We assessed various methods for setting condition thresholds around baseline conditions for meadow biomass, meadow area, and percent composition of species in each meadow. These methods included percentile bands, standard deviations, and percent change above and below the baseline. The 10 year fixed mean (calculated over the period from 2002 – 2012) was considered the most appropriate baseline for which to compare annual indicator values because it incorporates the greatest range of climate conditions known to influence seagrasses in the region for the different assessment periods examined. Several threshold ranges were used, recognising that the biomass, area and species composition in some seagrass meadows are historically stable, while others are relatively variable over time. These differences reflect the changes in species assemblages and growth characteristics at individual monitoring meadows, and spatial variation between meadows growing in marginal inner harbour conditions, versus more favourable mid harbour conditions. The Gladstone Harbour Report Card assesses annual levels for each seagrass condition indicator against baseline conditions to determine a grade from A to E, where A indicates a condition of ‘very good’ and E indicates a condition of 'very poor'. In 2015 a scale was applied to each grade so a score between 0 and 1 could be calculated for each indicator. The lowest of the three indicator scores dictates the overall meadow score and grade. The harbour is divided into 13 reporting zones as part of the GHHP reporting process, 6 of which contain seagrass monitoring meadows. Where multiple monitoring meadows were present within a zone, the mean of the overall meadow scores dictates the overall zone score and grade. Three Gladstone Harbour Zones were determined to be in satisfactory condition (Western Basin, Mid Harbour and South Trees Inlet (lower)), two zones were in poor condition (Inner Harbour and Rodds Bay), and one zone was in very poor condition (The Narrows). The Gladstone Harbour score is the mean of the overall zone scores. An assessment of 14 seagrass monitoring meadows determined that the overall condition of seagrass in the Gladstone Harbour region in 2014 was poor (grade D). The report is presented into two parts. Part 1 presents the report card results for the most recent annual survey conducted in November 2014 (in the GHHP 2014-2015 reporting year). Part 2 is an accompanying technical report detailing the methods for data collection, a comparison of different methods tested to set thresholds, justification for the threshold methods used for the 2015 report card, and a detailed presentation and interpretation of the results.

Item ID: 45232
Item Type: Report (Report)
Keywords: report card, seagrass, monitoring, Great Barrier Reef, Gladstone Healthy Harbours Partnership, Port Curtis, indicators
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ISP001: Seagrasses

A Report for the Gladstone Healthy Harbour Partnership. Report No. 15/29

Funders: Gladstone Healthy Harbour Partnership
Date Deposited: 30 Aug 2016 04:58
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 50%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960609 Sustainability Indicators @ 50%
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