This dataset describes the predicted distribution of seagrass communities across the Great Barrier Reef World Heritage Area
and adjacent estuaries, based on six multivariate regressions tree models for estuary intertidal, estuary subtidal, coastal
intertidal, coastal subtidal, reef intertidal, and reef subtidal. The models are presented as six raster datasets with
Managing seagrass resources in the GBRWHA requires adequate information on the spatial extent of seagrass communities.
The enormous size of the GBRWHA (1000s of kilometres) and the remoteness of many seagrass meadows from human populations
means that models are a useful tool to predict where different seagrass communities are likely to be in areas where data
James Cook University’s Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER) has been collecting spatial data
on GBR seagrass since the early 1980s. This project used TropWATER’s synthesis of seagrass site data (NESP Project 3.1 and
5.4: https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88) to predict seagrass communities.
In making this data publically available for management, the authors from the TropWATER Seagrass Group request being contacted
and involved in decision making processes that incorporate this data, to ensure its limitations are fully understood.
The sampling methods used to study, describe and monitors seagrass meadows were developed by the TropWATER Seagrass Group
and tailored to the location and habitat surveyed; descriptions and references are available in the metadata for the GBRWHA
data composite (https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88).
Environmental predictors used in the models were: depth below mean sea level (Beaman 2017), relative tidal exposure (Bishop-Taylor
et al. 2019), water type (Marine Water Bodies definitions version 2_4, Data courtesy of the Great Barrier Reef Marine Park
Authority; Dyall et al. 2004), proportion mud in the sediment (coast and reef models, https://research.csiro.au/ereefs/models/model-outputs/access-to-raw-model-output/) (see also Baird et al. 2020; Margvelashvili et al. 2018), dominant sediment (estuary models only; https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88), benthic geomorphology (Heap and Harris 2008), benthic light http://dapds00.nci.org.au/thredds/catalog/fx3/gbr1_bgc_924/catalog.html (see also Baird et al. 2016; Baird et al. 2020), water temperature, mean current speed and salinity http://thredds.ereefs.aims.gov.au/thredds/s3catalogue/aims-ereefs-public-prod/derived/ncaggregate/ereefs/gbr1_2.0/all-one/catalog.html?dataset=EREEFS_AIMS-CSIRO_gbr1_2.0_hydro_all-one.nc (Steven et al. 2019), wind speed (http://thredds.ereefs.aims.gov.au/thredds/s3catalogue/aims-ereefs-public-prod/derived/ncaggregate/ereefs/gbr1_2.0/all-one/catalog.html?dataset=EREEFS_AIMS-CSIRO_gbr1_2.0_hydro_all-one.nc ) and Australian Bureau of Meteorology’s ACCESS data products (Bureau of Meteorology 2020; Soldatenko
et al. 2018; Steven et al. 2019), and latitude. Different models had different combinations of predictors after removing
collinear variables and excluding variables that did not extend into an area. For example, estuary models only include depth,
relative tidal exposure, dominant sediment, and latitude.
We modelled seagrass communities in six areas: Estuary Intertidal, Estuary Subtidal, Coastal Intertidal, Coastal Subtidal,
Reef Intertidal and Reef Subtidal. For each area we used multivariate regression trees to examine changes in seagrass community
type within the GBRWHA and adjacent estuaries, using a matrix of seagrass presence/absence site data for 12 seagrass
species in the data set. Multivariate regression trees (MRTs) were implemented using the R package mvpart (De’ath 2004)
(available in archive form on CRAN at https://cran.r-project.org) in R version 4.0.2 (R Core Team 2020). The map in Figure 1 was created using ArcGIS 10.8.
A detailed description of the modelled communities can be found in the final report for the NESP TWQ Project 5.4 (currently
Seagrass community types were modelled within potential seagrass habitat. Potential seagrass habitat was modelled by Carter
et al. 2020 and is available on eAtlas here: https://eatlas.org.au/data/uuid/108ee868-4fb1-4e5f-ae57-5d65198384cc . The models do not extend north and south of the GBRWHA. The models extend across the continental shelf but exclude waters
deeper than ~100m east of the shelf that were not surveyed for seagrass. Data were included when sites extended west of
the GBRWHA boundary into coastal and estuarine water immediately adjacent.
The site data used in this model is available here: https://eatlas.org.au/data/uuid/5011393e-0db7-46ce-a8ee-f331fcf83a88)
Further information can be found in the upcoming publications of the final report for the NESP TWQ Project 5.4.
Limitations of the data:
The site data used in these models extends back to the mid-1980s. Large parts of the coast have not been mapped for seagrass
presence since that time. The seagrass community rasters are at 30m grid resolution, however some environmental variables
such as those from eReefs (wind speed, current speed, benthic light, water temperature) are from spatial data at 1km grid
resolution, and are likely to vary at much smaller spatial scales that we could not include in these models.
This dataset consists of six raster datasets with a geographic coordinate system of WGS84. The rasters have been saved as
layer packages with symbology representing seagrass communities. These are:
Estuary intertidal communities: GBR_seagrass_communities_estuary_intertidal.lpk
Estuary subtidal communities: GBR_seagrass_communities_estuary_subtidal.lpk
Coastal intertidal communities: GBR_seagrass_communities_coastal_intertidal.lpk
Coastal subtidal communities: GBR_seagrass_communities_coastal_subtidal.lpk
Reef intertidal communities: GBR_seagrass_communities_reef_intertidal.lpk
Reef subtidal communities: GBR_seagrass_communities_reef_subtidal.lpk
This dataset is filed in the eAtlas enduring data repository at: data\custodian\2019-2022-NESP-TWQ-5\5.4_Seagrass-Burdekin-region
Additional licensing information:
TropWATER gives no warranty in relation to the data (including accuracy, reliability, completeness, currency or suitability)
and accepts no liability (including without limitation, liability in negligence) for any loss, damage or costs (including
consequential damage) relating to any use of the data. TropWATER reserves the right to update, modify or correct the data
at any time. The limitations of some older data included need to be understood and recognised. The TropWATER Seagrass Group
would appreciate the opportunity to review documents providing research, management, legislative or compliance advice based
on this data.
Great Barrier Reef, Australia
Seagrass data north and south of the GBRWHA were excluded from the layers. The models extend across the continental shelf
but exclude waters deeper than ~100m east of the shelf that were not surveyed for seagrass. Data were included when sites
extended west of the GBRWHA boundary into coastal and estuarine water immediately adjacent.