Seagrass meadows of Hervey Bay and the Great Sandy Strait, Queensland, derived from field surveys conducted 6-14 December, 1998

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Approximately 2,362 ±289 km2 of seagrass meadows were mapped in the waters of Hervey Bay and Great Sandy Strait between 6 and 14 December 1998. This was the first comprehensive survey of the Great Sandy region. The survey involved examination of 1,104 field validation points and identified 174 individual meadows. Seagrass extended from the intertidal and shallow subtidal waters to a depth of 32m. Seven species of seagrass were identified (Cymodocea serrulata, Halodule uninervis, Syringodium isoetifolium, Halophila decipiens, Halophila ovalis, Halophila spinulosa and Zostera muelleri) within 22 seagrass meadow/community types. Mapping survey methodologies followed standardised global seagrass research methods for intertidal, shallow subtidal (2‐10m depth) and deep waters (>10m) using both in situ and remote assessments.

View the original metadata record at https://doi.org/10.1594/PANGAEA.876714.

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Statement: Mapping survey methodologies followed standardised global seagrass research methods (McKenzie et al. 2001a, bit.ly/2t7U4M4) using both in situ and remote assessments. Within intertidal and shallow subtidal waters (2-10m depth), observers walked or free-dived to assess survey points. Seagrass habitat characteristics including visual estimates of above-ground percentage cover or biomass (3 replicates of a 50cm x 50cm quadrat) and species composition were recorded at each point according to standard methodologies (McKenzie et al. 2001b, bit.ly/2t5SWsK; McKenzie et al. 2014, bit.ly/2rN4EUN). Water depth and visual/tactile description of sediment were also recorded at each survey point. At each deep water point (>10m) a real time video slaved to monitor on-board a vessel was used to record an image of bottom habitat for 4 to 6 minutes of time at drift speed (minimum 100m tow). Data on seagrass species presence and biomass, macro-algae, and sediment description was obtained from post processed video images as per Coles et al. (2009, bit.ly/2s28gXc). In conjunction with each camera tow a sled net and grab sample of the sediment were collected to confirm the taxonomy and sediment characterisation inferred from the video. A differential handheld global positioning system (GPS) was used to locate each survey point (accuracy ±5m). Seagrass meadow boundaries were determined based on the survey point positions and the presence of seagrass, coupled with depth contours and remote sensing (e.g., aerial photography) where available. The meadow boundary accuracy varied from 5m to 1,200m. The resulting polygon data of each seagrass meadow was saved as an ArcMap shapefile and projected to AGD94. -----DATA DICTIONARY----- MDW_ID unique meadow ID MEADOW description of meadow based on seagrass species present, seagrass abundance and sediment type (visual/tactile description of sediment). Nomenclature used: Species A = Species A is 100% of composition; Species A with Species B = Species A is 60% of composition; Species A with Species B/Species C = Species A is 50% of composition; Species A/Species B = Species A is 50% ‐ 60% of composition. Species listed below. BIOMASS mean visual estimate of above ground seagrass standing crop (all species pooled) expressed in grams dry weight (g DW m‐2 ) +/‐ standard error PERCNT_CVR mean or percentage range (%) of the substrate covered by seagrass (all species pooled) AREA area of polygon in km2 for each seagrass meadow with error (±) estimate of Reliability (based on positional accuracy) ALGAE mean percentage (%) of the substrate covered by macroalgae (all species pooled) (range) ALGAL_SPP description of macroalgae type and / or genus. Species from Cribb (1996, bit.ly/2rMG5Y1). DEPTH mean water depth (range) (m) QUALITY A rank system for mapping quality based on the range of mapping information available for each area (see Table 1). A mapping quality rank of 1 is the highest (most accurate). RELIABILIT An ‘estimate of reliability’ (R) of the areal extent (km2) of each meadow was also calculated based on the errors associated with GPS fixes for survey points and digitising/rectifying the aerial photograph. Estimates of reliability in mapping meadow boundaries ranged from 7.5 m to 1,200 m. CS mean visual estimate of above ground biomass (g DW m‐2) of Cymodocea serrulata (broad strap‐like leaf, leaftip rounded with serrated edge and attached to rhizome by a stem (www.seagrasswatch.org/id_seagrass.html#IDCS1)) HD mean visual estimate of above ground biomass (g DW m‐2) of Halophila decipiens (oblong leaf, 6‐8 cross veins, leaf hairs on both sides (www.seagrasswatch.org/id_seagrass.html#IDHD1)) HO mean visual estimate of above ground biomass (g DW m‐2) of Halophila ovalis (paired oval to oblong leaves, leaf margins smooth, 8 or more cross veins, no leaf hairs (www.seagrasswatch.org/id_seagrass.html#IDHO1)) HS mean visual estimate of above ground biomass (g DW m‐2) of Halophila spinulosa (errect shoots with oblong shaped leaves arranged in opposite pairs (www.seagrasswatch.org/id_seagrass.html#IDHS1)) HU mean visual estimate of above ground biomass (g DW m‐2) of Halodule uninervis (strap‐like leaf with stem, leaf tip tri‐ dentate (www.seagrasswatch.org/id_seagrass.html#IDHU1)) SI mean visual estimate of above ground biomass (g DW m‐2) of Syringodium isoetifolium (cylindrical spaghetti shaped leaves, 7‐30cm long, pointed tip (www.seagrasswatch.org/id_seagrass.html#IDSI1)) ZM mean visual estimate of above ground biomass (g DW m‐2) of Zostera muelleri (strap‐like leaves with 5 longitudinal veins arising directly from rhizome, smooth rounded leaf tip (www.seagrasswatch.org/id_seagrass.html#IDZC1))