Predator's pick: Lobster predation on urchins - data from experimental investigation

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This data is from experiments conducted at IMAS Taroona laboratories on predation of urchins by the Southern Rock Lobster. Four experiment types were conducted, including live urchins, urchin roe and trimmed urchins.

This data directly supports the publication https://doi.org/10.1071/MF23140

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Maintenance and Update Frequency: notPlanned

Statement: Four separate captive feeding experiments were conducted at IMAS Taroona facilities, Tasmania, between 2020-2024 (Table 1). All lobsters used in experiments were collected by hand on SCUBA or by baited pot from either Elephant Rock Research Reserve (St Helens, North-East Tasmania) or Crayfish Point Research Reserve (Taroona, South-East Tasmania). Lobsters were collected under permit from the Tasmanian Government (#24068). Elephant Rock Research reserve represents a site of extensive urchin barren with high abundance of C. rodgersii and these lobsters are considered ‘familiar’ with the alien species. In comparison, Crayfish Point Research Reserve represents a kelp-dominated reef beyond the urchin invasion front, where C. rodgersii have not been recorded, therefore these lobsters are considered ‘naïve’. Experiments were all conducted in austral summer (November – February) to avoid behavioural impact of moulting and maximise likelihood of predation occurring (Kelly et al., 1999). Prior to experiments, lobsters were held communally in large 3000l tanks with ample sheltering. During experiments all lobsters were kept in individual tanks and were allowed at least 24 hours to acclimatise to their tank environment. All tanks were under cover or inside and had constant flow of filtered raw seawater. Urchins (C. rodgersii and H. erythrogramma) for all experiments were collected by divers from sites where kelp was present (i.e., not barrens) to ensure consistent prey quality (Eurich et al., 2014). Urchin collection sites included Fortescue Bay (both species) and Dodges Ferry (H. erythrogramma only). Urchins were collected under permit from the Tasmanian Government (#24088). Urchins were kept in holding tanks (400-2000-l) and fed drift kelp to maintain health. Lobsters were split into three size classes: small (carapace length [CL] < 110 mm), medium (CL 110–140 mm), and large (CL > 140 mm). Urchins were always offered within the gape-limitation threshold and best efforts were made to match offered urchin size (test diameter, TD) to the size of the lobster using the size relationship (Ling et al., 2009). Where experiments were recorded, tanks were lit with red LED strip lights (Fluval Aquasky 2.0, USA) hanging above the water to allow filming in the dark with least disturbance to the animal. GoPros on timelapse mode were used to monitor activity and videos were analysed manually. For more information, please see the associated publication [link TBC].