Coral recruitment patterns within and among reefs in the Cairns-Port Douglas region from 2023/2024-2024/2025 (RTP, Reef Hub, JCU TropWATER)

This dataset consists of two years of relative coral recruitment from within and among reefs in the Cairns-Port Douglas region from 2023 to 2025. The dataset includes one csv of the site gps coordinates where recruitment tiles were deployed during annual mass spawning periods in 2023/2024 and 2024/2025. A second csv file provides a summary of recruits recorded per tile at each site in total and, where possible, total recruits for three Scleractinia family groups or ‘Other’ where not identifiable. Recruit data is also recorded as the total number of recruits per side of each tile (‘top’, ‘bottom’, and ‘sides’). The third csv provides Rapid Health Impact Survey data collected at the same sites and time where and when tiles were deployed. A fourth csv provides the temperature recorded in situ at sites where recruitment tiles were deployed over a continuous two-year period where possible with some data omissions due to logger failure or loss.

Methods:

Settlement tiles were deployed at 5 reefs (Opal Reef, Agincourt Reef, Hastings Reef, Moore Reef, Flynn Reef) across 15 sites over two years to quantify relative coral recruitment following mass spawning periods (November – January each year). In year 2 (2024/2025), a sixth reef, Rudder Reef, was added to the study with three additional sites. Sites were located at a similar depth stratum (6-8 m below mean sea level) in a similar reef zonation in the back reef lagoon. At each site, 15 recruitment tiles were deployed. Tiles were constructed from locally quarried limestone and cut to standard dimensions (9 × 9 × 1 cm). A single hole was drilled through the centre of each tile in order to be mounted on 8 mm stainless steel rods (~20 cm length), which were inserted 5–10 cm into reef substrate. Tiles were spaced ~5 m apart within a maximum spatial extent of 100 m per site. Two cable ties were secured at the base of rods for the tiles to rest on in order to create a ~1.5cm space between the reef substrate and tile. Prior to deployment, a light ‘X’ groove had been etched using a small rotary drill to the underside of each tile in order to differentiate the top orientation from the bottom orientation when retrieved from deployment periods. A rubber washer was placed at the top of each metal rod after the tile was added to ensure tiles could not be dislodged from rods during deployment periods. Tiles were deployed each year approximately six weeks prior to expected mass spawning events which were predicted to be 3-5 nights following the November full moon. This period allowed natural biofilm and benthic community development to condition tile surfaces. 

Temperature loggers were also secured in place at each reef site adjacent to deployed tiles and left in place over the entirety of the two year study apart from logger change outs at six month intervals to mitigate data or logger losses. Rapid Health Impact Surveys (Beeden et al. 2014) were carried out at the time of tile deployment or within a few weeks of deployment. GPS locations were recorded at all study sites.  

Tiles were left in place four to six weeks following the subsequent January full moon to capture the variety of species that may spawn across these known peak spawning months on the Great Barrier Reef equating to 90-105 days for tile deployments in total. Retrieved tiles were threaded onto metal rods separated by 2 cm rubber spacers to prevent contact and damage during transport. A small number (1-2) tiles were lost at some sites especially following TC Jasper impacts in year 1. Tiles on rods were carefully mounted in milk crates or similar containers to avoid tile damage. Retrieved tiles were left on metal rods but placed in large nally tubs where they were fully submerged in a 24 hour, 10% bleach solution to remove all living material. Tiles were gently rinsed and allowed to air dry before being returned to the lab for further analysis. 

In the lab, tiles were assessed on all surfaces for hard coral recruits using stereo microscopes. Tiles were carefully handled to avoid to damage to skeletal structures and placed in plastic containers on rubber spacers to avoid abrasion during microscope assessments. A 9cm x 9cm grid was placed over each tile in order to track exact location under the microscope and all recruits were transferred to a mirrored datasheet for each tile.

Coral recruits were defined as newly settled individuals identifiable by the presence of a calcareous skeleton and primary septal structures under magnification. Recruits of both broadcast spawning and brooding species were quantified despite the study’s focus around large scale broadcast spawning events. Based on deployment period of tiles, all recruits are estimated to be a maximum of 12 weeks old. Hard coral recruits were identified to a limited level as either belonging to the family Acroporidae, Pocillporidae or Poritidae, or ‘Other’ if they were not one of these but clearly a member of the Scleractinia Order based on anatomical skeletal features. This lack of taxonomic resolution is largely due to only these 3 families as being reliably distinguished at this early life stage based on anatomical identifying features described by Babcock et al. 2003. Hard coral recruits were also collated by the orientation on which surface they had settled: ‘Top’, ‘Bottom’, or ‘Sides’. Estimates of number of hard coral recruits are all reported as recruits per tile or per surface.

Limitations of the data:

This coral recruitment dataset provides a relative measure of recruitment of 8-12 week old Scleractinia corals onto limestone based tiles that have been pre-conditioned and deployed to sites 6-8 weeks prior to predicted annual mass spawning events in the Cairns-Port Douglas region. Sites selected are similar in reef zonation and within 6-8 meters below mean low tide to ensure comparable among sites and reefs. Data is not meant to be a measure of absolute recruitment to a particular site and is part of a longitudinal study that will be added to annually where possible to look at long term trends in relation to external driving factors (e.g. disturbances, recovery etc.).

Format of the data:

This dataset is a collection of 4 csv files with the following description of each: 
1.  Recruit_tiles_site_coordinates.csv
 Reef and site name along with gps coordinates of the location of recruitment tiles deployed.
<ol>
<li>

Recruit_data_2023-24_2024-25_v1.csv
Summary of Scleractinia coral recruits recorded per tile, to the family level where possible (Acroporidae, Pocilloporidae, Poritidae and Other) and separated into total number of recruits recorded on the ‘top’, ‘bottom’, and ‘sides’ of each tile.
</li>
<li>

Recruit_tiles_RHIS_surveys_v1.csv
Rapid Health Impact Surveys completed at the time of recruitment tile deployment at each site.
</li>
<li>

Master_temp_data2025_v1.csv
Temperature records recorded using in situ loggers deployed at recruitment tile gps locations. Temperature was recorded at one hour intervals and in continuous apart from data gaps due to logger failure or logger loss.
</li>
</ol>

Data dictionary:
<ol>
<li>Recruit_tiles_site_coordinates.csv</li>
<li>Reef: reef name for recruit tile deployment, RHIS and temperature data</li>
<li>Site: site name that matches for recruit tile deployment, RHIS and temperature data</li>
<li>Latitude: WGS 1984</li>
<li>

Longitude: WGS 1984
</li>
<li>

Recruit_data_2023-24_2024-25_v1.csv
</li>
<li>Reef: reef name for recruit tile deployment</li>
<li>Site: site name for recruit tile deployment</li>
<li>Year_deployed: the year tiles were deployed</li>
<li>Year_analysed: the year tiles were analysed under microscopes after retrieving from reef sites</li>
<li>Date_analysed: the date tiles were analysed under microscopes in dd/mm/yyyy format</li>
<li>Operator: the name of the organisation who assisted with deployment/retrieval of recruitment tiles at a given reef site due to moorings or specific interest by these groups at these reef sites</li>
<li>Observer: the name of the individual who recorded data on a given tile after being trained and cleared by JCU staff following QAQC protocols</li>
<li>Tile_number: the recruitment tile number assigned to a given tile at a reef site</li>
<li>Acroporidae_total: the total number of recruits recorded on all sides of a tile that were identified as belonging to the Acroporidae coral family</li>
<li>Pocilloporidae_total: the total number of recruits recorded on all sides of a tile that were identified as belonging to the Pocilloporidae coral family</li>
<li>Poritidae_total: the total number of recruits recorded on all sides of a tile that were identified as belonging to the Poritidae coral family</li>
<li>Other_total: the total number of recruits recorded on all sides of a tile that were identified as belonging to something other than the coral families above (Acroporidae, Pocilloporidae, or Poritidae)</li>
<li>Total_recruits: the total number of recruits recorded on all sides of a tile</li>
<li>Total_top: the total number of recruits recorded on the top surface of a tile</li>
<li>Total_bottom: the total number of recruits recorded on the bottom surface of a tile</li>
<li>

Total_sides: the total number of recruits recorded on the side surfaces of a tile
</li>
<li>

Recruit_tiles_RHIS_surveys_v1.csv (headings following standard RHIS protocol collection. See Beeden et al. 2014 for details https://link.springer.com/article/10.1007/s10661-014-4022-0 )
</li>
<li>Reef: reef name for recruit tile deployment</li>
<li>Site: site name for recruit tile deployment</li>
<li>Spawning_Year: the year tiles were deployed for spawning events</li>
<li>Date: the date the RHIS was completed in dd/mm/yyyy format</li>
<li>Operator: tourism operator or other organisation responsible for survey data</li>
<li>Live_coral: percentage of benthic cover that is live coral</li>
<li>Macroalgae: percentage of benthic cover that is macroalgae</li>
<li>Live_coral_rock: percentage of benthic cover that is live coral rock</li>
<li>Recently_dead_coral: percentage of benthic cover that is recently dead coral</li>
<li>Coral_rubble: percentage of benthic cover that is coral rubble</li>
<li>Sand: percentage of benthic cover that is sand</li>
<li>Soft_coral: proportion of coral cover (live and recently dead) that is soft coral</li>
<li>Branching_hard: proportion of coral cover (live and recently dead) that is branching hard coral</li>
<li>Bushy_hard: proportion of coral cover (live and recently dead) that is bushy hard coral</li>
<li>Plating_hard: proportion of coral cover (live and recently dead) that is plating hard coral</li>
<li>Foliose_hard: proportion of coral cover (live and recently dead) that is foliose hard coral</li>
<li>Encrusting_hard: proportion of coral cover (live and recently dead) that is encrusting hard coral</li>
<li>Solitary_hard: proportion of coral cover (live and recently dead) that is solitary hard coral</li>
<li>Massive_hard: proportion of coral cover (live and recently dead) that is massive hard coral</li>
<li>Slime_algae: proportion of total macroalgal cover that is slime algae</li>
<li>Mat_algae: proportion of total macroalgal cover that is entangled/mat-like algae</li>
<li>Filamentous_algae: proportion of total macroalgal cover that is filamentous algae</li>
<li>Leafy_algae: proportion of total macroalgal cover that is leafy/fleshy algae</li>
<li>Bushy_algae: proportion of total macroalgal cover that is tree/bush-like algae</li>
<li>Bleaching: impact present (Y/N)</li>
<li>Disease: impact present (Y/N)</li>
<li>Predation: impact present (Y/N)</li>
<li>

Damage: impact present (Y/N)
</li>
<li>

Master_temp_data2025_v1_tall.csv
</li>
<li>Reef: reef name</li>
<li>Site: site name</li>
<li>Date: Date (dd/mm/yyyy)</li>
<li>Time: Time (hh:mm:ss)</li>
<li>Temperature: Temperature (Celsius) for each Site within Reef</li>
</ol>

eAtlas processing:
- Recruit_data_2023-24_2024-25_v1.csv: de-identify observer names
- Recruit_tiles_RHIS_surveys_v1.csv: make column titles consistent
- Recruit_tiles_site_coordinates.csv: fix "Little Traceys"
- Master_temp_data2025_v1.csv: transform wide table into tall table
- Generate shapefiles from Recruit_data_2023-24_2024-25_v1.csv and Recruit_tiles_RHIS_surveys_v1.csv
- Generate plots from Recruit_data_2023-24_2024-25_v1.csv and Master_temp_data2025_v1.csv

References:

Babcock, R. C., Baird, A. H., Piromvaragorn, S., Thomson, D. P., &amp; Willis, B. L. (2003). Identification of scleractinian coral recruits from Indo-Pacific reefs. ZOOLOGICAL STUDIES-TAIPEI-, 42(1), 211-226.

Beeden, R.J., Turner, M.A., Dryden, J. et al. Rapid survey protocol that provides dynamic information on reef condition to managers of the Great Barrier Reef. Environ Monit Assess 186, 8527–8540 (2014). https://doi.org/10.1007/s10661-014-4022-0

Location of the data:

This dataset is filed in the eAtlas enduring data repository at: 
data\custodian\2022-2029-RRAP\GBR_JCU_RTP_Coral-recruitment_2023-2025\data

Tags: Corals, Marine, World
Organization: Australian Ocean Data Network