Chemosensory behaviour of juvenile crown-of-thorns sea stars (Acanthaster sp.), attraction to algal and coral food, and avoidance of adult conspecifics

Intraspecific and habitat-mediated responses to chemical cues play key roles in structuring populations of marine species. We investigated the behaviour of herbivorous-stage juvenile crown-of-thorns sea stars (COTS: Acanthaster sp.) in flow-through choice chambers to determine if chemical cues from their habitat influence movement and their transition to becoming coral predators. Juveniles at the diet transition stage were exposed to cues from their nursery habitat (coral rubble-crustose coralline algae -CCA), live coral, and adult COTS to determine if waterborne cues influence movement. In response to CCA and coral as sole cues juveniles moved toward the cue source and when these cues were presented in combination, they exhibited a preference for coral. Juveniles moved away from adult COTS cues. Exposure to food cues (coral, CCA) in the presence of adult cues resulted in variable responses. Our results suggest a feedback mechanism whereby juvenile behaviour is mediated by adult chemica..., Specimens and rearing condition
As the taxonomy of the Pacific species of Acanthaster is uncertain (1), the species investigated here is referred to as Acanthaster sp. or COTS. Adults were collected near Cairns (northern GBR) by COTS control divers and shipped to the Sydney Institute of Marine Science where they were maintained in flow-through aquaria (filtered sea water, FSW 5 µm) at 26 °C, the temperature of their habitat (http://data.aims.gov.au/aimsrtds/yearlytrends.xhtml). For each of the three fertilisations, the gametes of two different males and two females were used, and the larvae were reared to the settled juvenile stage following routine methods (2). Larvae with a well-developed juvenile rudiment (14–16 days post-fertilization) were induced to settle using coralline algae (Amphiroa sp.). The juveniles were maintained in a constant temperature room (26 °C, 12:12 hr light cycle) in UV sterilised 1 µm FSW with ambient salinity of ~ 34 % (Merck salinity probe) and fed small fron..., , # Chemosensory behaviour of juvenile crown-of-thorns sea star (*Acanthaster* sp.), attraction to algal and coral food, and avoidance of adult conspecifics.

[https://doi.org/10.5061/dryad.0k6djhb6k](https://doi.org/10.5061/dryad.0k6djhb6k)

We have submitted our raw data **(Webb_et.al_2024.CSV)** on juvenile behaviour 

### Choice Response Data (Sheet 1):

Choice response of juvenile Crown of Thorns Sea Stars (COTS; *Acanthaster sp*.) when exposed to cues from crustose coralline algae (CCA) rubble, live coral, and adult conspecifics.

* *Treatment:* The combination of cues exposed to a juvenile COTS
* *Juvenile Choice Response:* The direction of movement or no movement made by the juvenile COTS.
* *Count:* The number of juveniles that made each choice response. 

*Abbreviations included

### Chi-squared analysis (Sheet 2):

Chi-squared goodness of fit analysis of the choice response data in sheet 1. Analyses were conducted in R (version 1.2.1335) using Pearson's Chi-squared test f...