Effect of invasive tagging on the activity behaviour of Holothuria whitmaei (sea cucumber) at Ningaloo Reef, Western Australia

Brief description

Data were collected to evaluate the practicality of marking the dorsal tegument as a tagging method for short-term mark-recapture studies of holothurians (Holothuria whitmaei, Bell 1887) and to compare the behaviour of 'marked' to 'unmarked' control animals.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Thirty adult H. whitmaei were located within a 1 ha section of reef flat located approximately 3 km south west of Coral Bay, Ningaloo Reef, Western Australia. Fifteen of the animals were selected at random and marked with a number approximately 30 by 20 mm. Numbers were scratched into the dorsal tegument of each specimen to a depth of approximately 1 to 2 mm, such that the underlying white flesh was clearly visble beneath the contrasting dark skin. To ensure that each animal was subjected to the same degree of disturbance, only single digits were applied to teh tegument. Where double digit numbers were required (i.e. animal numbers 10 to 15), only the second digit was used. Animals marked with the same number (i.e. animals 1 and 11, 2 and 12, 3 and 13, and so forth) were sufficiently spaced so that the identity of specimens was clearly apparent (i.e. the paths travelled by these animals has no opportunity for overlap). None of the remaining fifteen animals were marked, but each was briefly disturbed by hand to control for behavioural artfact that may have resulted from the handling process alone. Additional animals not included in the study were collected and removed from the area. Immediately following the marking procedure, numbered marker plates were placed directly posterior to each animal, from which point all subsequent movement was determined. Identifying the paths of individual animals was possible simply by following the faeces of the sea cucumbers, which are deposited as visible 'strings' or pellets along the route taken by the animal. To record the total distance travelled, a flexible measuring tape was used to measure the distance along the faeces trail left posterior to each specimen. Marker plates were then carefully returned to the substrate immediately posterior to each sea cucumber, taking care not to disturb the animal. Rates of activity, calculated as the total distance travelled, (cm) divided by time (h), were monitored three times during daylight hours (between 08:30-11:30 h, 11:30-14.30 h and 14:30-17:30 h) and once over night (between 17:30-08:30 h). Night time rates of activity were calculated based upon the total distance travelled between the last dive of the day and the first dive of the following day, divided by the number of hours between measurements.