Prevalence and severity of sub-lethal injuries in COTS across different management zones from 2012 - 2020 (NESP TWQ 4.1, ARC COE, JCU)

This dataset collected variation in the demography of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) during the latest period of elevated starfish densities (active population irruptions) in the central section of Australia’s Great Barrier Reef. Specifically, we examined variation in i) the prevalence and severity of sub-lethal injuries among juvenile and adult crown-of-thorns starfish, and ii) the recruitment, growth and survivorship of early-stage juvenile starfish, across different management zones where fishing is restricted (Habitat Protection Zone, Conservation Park Zone) versus effectively prohibited (Marine National Park Zone).

Methods:

Prevalence of severity of injuries in adult crown-of-thorns starfish
A total of 5,238 Pacific crown-of-thorns starfish (Acanthaster cf. solaris) were sampled across 80 reefs in the Great Barrier Reef Marine Park, building substantially on the sample (n = 3,846) of starfish analysed previously (Messmer et al. 2017). All starfish were carefully extracted from the reef matrix, using purpose-built large stainless-steel tongs or hooks, taking care not to damage the starfish. Starfish were then kept in mesh bags or perforated collection boxes for transport to support vessels. All starfish were processed within 3 hours of collection, except where we had access to holding facilities with large tanks and rapid exchange of fresh seawater (e.g., at Lizard Island Research Station) and could maintain the starfish for prolonged periods with limited adverse effects on individual condition.

Determining evidence of injuries (Rivera-Posada et al. 2014)
The total diameter of individual starfish was measured by inverting starfish on a flat surface and measuring the distance between tips of opposite and undamaged arms. Measurements were taken (to the nearest mm) from the termination of the ambulacral grooves and ignoring the spines projecting from the tips of the arms. Where starfish were noticeably asymmetrical, the diameter was measured at least twice and then averaged. The underside (oral surface) of starfish was then examined to determine the number of arms, and evidence of injuries. The total number of arms was counted based on the number of discrete ambulacral grooves extending directly from the oral cavity. Arms were considered to be damaged if they were less than 75% the length of the other seemingly intact arms, or were conspicuously damaged, missing or regenerating. Recent injuries (e.g., fresh tears in the surface integument) were disregarded, as they likely occurred during collection. The incidence of injuries was determined based on the proportion of starfish with any evidence of injuries, whereas severity of injuries was estimated based on the proportion of an individual’s arms that were injured. Where only the number of injured arms was recorded, this was expressed as a proportion, using the median number of arms (15) recorded for all A. cf. solaris where the number of arms was counted.

Further information can be found in this publication: Rivera-Posada J, Caballes CF, Pratchett MS (2014) Size-related variation in arm damage frequency in the crown-of-thorns sea star, Acanthaster planci. Journal of Coastal Life Medicine 2:187-195

Variation in the incidence (proportion of individuals with injuries) and severity (proportion of arms damaged or missing on injured starfish) was compared among reefs within each of three different management zones; i) Marine National Park Zones (GREEN; “No-take”); ii) Conservation Park Zones (YELLOW; “Limited take”); and iii) Habitat Protection Zones (BLUE; “Take”) as well as across sizes of COTS.

Prevalence of severity of injuries in juvenile crown-of-thorns starfish (Wilmes et al. 2016, 2019, 2020)
Variation in the incidence and severity of injuries was also assessed for 200 early-stage juvenile A. cf. solaris (size range = 5–45 mm diameter) – presumed to be <1 year old. These early-stage juveniles were sampled from an extensive collection of early-stage juvenile starfish (n = 3,532) that had been collected on the GBR in 2015 (Wilmes and Schultz 2019). Sampling was in the present study intentionally biased towards the largest, and presumably oldest, individuals to avoid confusion between newly-forming versus regenerating arms. All starfish were collected on SCUBA (max depth = 15 m), during extensive searching in areas of unconsolidated coral rubble, interspersed with patches of consolidated carbonate and live corals. Starfish were preserved in 95% ethanol following collection for later processing.

Further information can be found in these publications: Wilmes J, Matthews S, Schultz D, Messmer V, Hoey A, Pratchett M (2016) Modelling growth of juvenile crown-of-thorns starfish on the northern Great Barrier Reef. Diversity. 9, 1; Wilmes JC, Hoey AS, Mesmer V, Pratchett MS (2019) Incidence and severity of injuries among juvenile crown-of-thorns starfish on Australia's Great Barrier Reef. Coral Reefs 38:1187-1195; Wilmes JC, Schulz DJ (2019) Size and diet of newly settled crown-of-thorns starfish from Australia's Great Barrier Reef. James Cook University (dataset); Wilmes JC, Schultz DS, Hoey AS, Messmer V, Pratchett MS (2020b) Habitat associations of settlement-stage crown-of-thorns starfish on Australia’s Great Barrier Reef. Coral Reefs 39, 1163-1174

The aboral side of each of the 200 juvenile starfish selected for this study was photographed using an Olympus Om-D E-M5 camera. For each starfish, the number of arms was counted and its maximum radius was measured from the centre of the aboral disc area to the tip of the longest arm (using ImageJ1). Injured arms were defined as those that were >10% shorter than the radial extent of the longest arm, following Bos et al (2011).

Further information can be found in this publication: Bos AR, Gumanao GS, Van Katwijk MM, Mueller B, Saceda MM, Tejada RL (2011) Ontogenetic habitat shift, population growth, and burrowing behavior of the Indo-Pacific beach star, Archaster typicus (Echinodermata; Asteroidea). Marine Biology 158:639-648

Recruitment and survival of juvenile crown-of-thorns starfish
Field studies were conducted in 2018 and 2019 at five mid-shelf reefs (Kelso Reef, Little Kelso reef, Rib Reef, Lodestone Reef and Keeper Reef) of the central GBR to explore variation in recruitment and survival of early-stage juvenile crown-of-thorns starfish between reefs where fishing was permitted (Habitat Protection Zone; n = 3) versus those where fishing was not allowed (Marine National Park Zone; n = 2). Each reef was surveyed twice each year (June and November). Reefs were selected to represent contrasting GBRMPA management zones, at the time of active CoTS outbreaks. The specific study locations at each reef were chosen following extensive surveys at selected locations, which identified areas with elevated densities of early-stage juvenile CoTS. The initial surveys in June 2018 were conducted at least 5 months after peak annual spawning and settlement (in late December and early January, respectively; Uthicke et al. 2019) as newly settled starfish are difficult to be visually detected prior to this time.

Survey methodology for juvenile crown-of-thorns starfish (Wilmes et al. 2020)
While study locations varied in their orientation to the prevailing south-east trade winds, they were all characterised by relatively steep slopes, enabling sampling of multiple depths (up to 15 m water depth). Surveys were conducted following an adapted version of Wilmes et al. (2020), using 60 replicate 1m × 1m quadrats to survey each location. Replicate quadrats were placed haphazardly, working systematically from the bottom of the reef slope up to the reef crest and avoiding areas comprised mostly or entirely of sand. To maximize detection of early-stage juvenile starfish, the area encompassed within each quadrat was further divided into quadrants, which were thoroughly searched in turn. All starfish detected (up to 200m diameter) were measured in situ.

Further information can be found in this publication: Wilmes JC, Hoey AS, Pratchett MS (2020) Contrasting size and fate of crown-of-thorns starfish linked to ontogenetic diet shifts. Proc R Soc B 287: 20201052

Format:

Dataset is saved .csv (COTS_Sublethal_Injury_Data.csv)

Data Dictionary:

- SAMPLE = Sample Label
- REGION = GBR Section
- REEF = Reef Name
- ZONE = Management Zone
- Blue Zone = Habitat Protection Zone (“Take”)
- Yellow Zone = Conservation Park Zone (“Limited Take”)
- Green Zone = Marine National Park Zone (“No-Take”)
- MaxD = Maximum Diameter
- Injured.Arms = Number of Injured Arms
- Total.Arms = Total Number of Arms
- Severity = Number of Injured Arms / Total Number of Arms
- PA = Presence/Absence of Injuries (Prevalence)

References:

Bos AR, Gumanao GS, Van Katwijk MM, Mueller B, Saceda MM, Tejada RL (2011) Ontogenetic habitat shift, population growth, and burrowing behavior of the Indo-Pacific beach star, Archaster typicus (Echinodermata; Asteroidea). Marine Biology 158:639-648

Rivera-Posada J, Caballes CF, Pratchett MS (2014) Size-related variation in arm damage frequency in the crown-of-thorns sea star, Acanthaster planci. Journal of Coastal Life Medicine 2:187-195

Wilmes J, Matthews S, Schultz D, Messmer V, Hoey A, Pratchett M (2016) Modelling growth of juvenile crown-of-thorns starfish on the northern Great Barrier Reef. Diversity. 9, 1

Wilmes JC, Hoey AS, Mesmer V, Pratchett MS (2019) Incidence and severity of injuries among juvenile crown-of-thorns starfish on Australia's Great Barrier Reef. Coral Reefs 38:1187-1195

Wilmes JC, Hoey AS, Pratchett MS (2020) Contrasting size and fate of crown-of-thorns starfish linked to ontogenetic diet shifts. Proc R Soc B 287: 20201052

Wilmes JC, Schultz DS, Hoey AS, Messmer V, Pratchett MS (2020b) Habitat associations of settlement-stage crown-of-thorns starfish on Australia’s Great Barrier Reef. Coral Reefs 39, 1163-1174

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\custodian\2018-2021-NESP-TWQ-4\4.1_COTS-surveillance