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Before‐After‐Control‐Impact (BACI) designs are widespread in environmental science, however their implicitly hierarchical nature complicates the evaluation of statistical power. Here, we describe epower, an r package for assessing statistical power of BACI designs. The package uses Bayesian statistical methods via the r‐package INLA to fit the appropriate hierarchical model to user supplied pilot survey data. A posterior sample is then used to build a Monte Carlo simulation to test statistical power specifically for the Before/After × Control/Impact interaction term in the BACI model. Power can be assessed for any number of user‐specified effect sizes for the existing design, or across a range of levels of replication for any part of the sampling design hierarchy. The package offers a user friendly robust approach for assessing statistical power of BACI designs whilst accounting for uncertainty in parameter values within a fully generalized framework.

Although mark-recapture techniques traditionally have been used to obtain ecological data, tagging of soft-bodied holothurians has proven difficult, and the degree to which invasive tags may confound the behaviour of holothurians remains unclear. In this study, diurnal patterns of activity were monitored in the commercial sea cucumber Holothuria whitmaei (black teatfish) after marking the tegument superficially with a number measuring 30 Â 20 mm (to a depth of 2 mm). Rates of activity in marked specimens increased significantly in the initial hours following marking, and remained higher than those of unmarked control animals for up to 3 days following the procedure. These results suggest (a) that behaviour in holothurians may initially be compromised by marking the tegument and (b) that improved measures of activity may be obtained following a suitable recovery period. This is a useful finding given the need for improved knowledge of commercial holothurian biology, including diurnal and seasonal patterns of behaviour.

The population density, activity and bioturbation contribution of the sea cucumber Holothuria whitmaei was investigated on Ningaloo Reef, Western Australia. Two methods, stratified manta tows and blanket manta tows, recorded population densities between 11.4 and >100 individuals (ind.) ha -1 . Further analysis revealed a heterogeneous pattern of distribution, with individuals tending to aggregate (Moran's I; 0.039; p < 0.05) on the outer reef lagoon and particularly in areas of high flow. Densities within aggregations were up to 7.2 times greater than those obtained after blanket manta tows (17.1 ind. ha -1 ), and 4.5 to 6.3 times greater than those obtained after traditional stratified manta tows (19.3 to 27.1 ind. ha -1 ). Behavioural studies, including investigations of activity and bioturbation, were conducted over a 2 yr time frame (2002)(2003) incorporating 3 monitoring periods within each year: January, April and August. Rates of activity varied diurnally, increasing between morning and afternoon, and seasonally, increasing in April, relative to January and August. Temporal patterns of feeding were more difficult to characterise; although rates of sediment egestion were in many cases higher in the morning, no conclusive diurnal or seasonal patterns could be established. Subsequent regression analysis, however, did find a significant positive correlation between the distance travelled and the volume of sediment egested. The volume of sediment bioturbated by H. whitmaei at a population level was found to represent only a small fraction of the sediments available (ca. 2 to 14% per annum), even though the contribution per individual was greater than that of smaller sea cucumber species. However, at maximum densities and typical rates of activity, H. whitmeai makes physical contact with approximately 2 times the available coral reef sediments per annum per hectare, simply by crawling. This may represent an important ecological contribution, particularly in light of previously documented links between sea cucumber activity, nutrient recycling and the enhancement of benthic microalgal communities.KEY WORDS: Aggregation · Behavioural activity · Bioturbation · Coral reef lagoon · Densitydependent effects Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 415: [127][128][129][130][131][132][133][134][135][136][137][138][139] 2010 tributed to a 'boom and bust' cycle where high-value sea cucumbers are targeted preferentially, leading to high-value species being fished to near local extinction (Rees et al. 2003) or to levels too low to sustain the fishery (Uthicke & Benzie 2000a).Previous studies of the ecology and biology of Holothuria whitmaei centred on the Great Barrier Reef (GBR), Queensland, Australia (Uthicke & Karez 1999, Uthicke & Benzie 2000a,b, 2002) and elsewhere in the broader Pacific Ocean (Conand 1981, Martinez & Richmond 1998. Several of these provide useful descriptions of the habitat preferences of H. whitmaei, which are described broadl...

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