Settlement plates as monitoring devices for non-indigenous species in marine fouling communities

Abstract

Experimental studies evaluating the effects of food availability on the movement of free-ranging animals generally involve food supplementation rather than suppression. Both approaches can yield similar insights, but we were interested in the potential for using food suppression for the management and control of invasive predators, in particular, the brown treesnake (Boiga irregularis) on Guam. However, understanding a species' response to food resources is critical before employing such a strategy. We studied the movements of 24 radio-tagged B. irregularis initially caught within four 4-ha unfenced plots in rodent-abundant (control) and rodent-suppressed (treatment) grassland habitats over a 40-day period. Because monitoring duration differed among snakes, we also analyzed short-term (16-day) activity areas. Over the 16 days, snakes associated with rodent-suppressed plots had 86% larger activity areas (ha), 94% greater dispersal distances (m), and 43% greater movement rates (m/h) than snakes associated with control plots. Boiga irregularis moved extensively, but these movements were not always reflected in the size of the snake's total activity area. Movement rates did not differ between sexes, but snakes in above-average body condition moved greater distances per hour than those in below-average condition irrespective of treatment. Our study indicates that a relatively small prey suppression effort can cause almost immediate and significant changes in B. irregularis movement. On Guam, prey suppression might enhance control efforts by either increasing trap capture success or discouraging snakes from entering areas of conservation or management concern. However, the outcome of using prey suppression as a control tool in areas threatened with the accidental introduction of the brown treesnake is more difficult to predict and might have negative consequences such as elevated dispersal rates.

A global analysis of complexity–biodiversity relationships on marine artificial structures

“…Heavy metals, such as copper, either historically or presently used in antifouling paints, can negatively impact native biodiversity (Dafforn et al, 2011;Kinsella & Crowe, 2016). Previous studies have demonstrated these contaminants can also enhance the richness and abundances of invasive species (Marraffini et al, 2017;Piola et al, 2009); thus complexity could facilitate the increase of the non-endemic species pool. Studies directly manipulating contamination inside and outside harbours would be required to establish the importance of this factor as a moderator of complexity effects.…”

Lessons from photo analyses of Autonomous Reef Monitoring Structures as tools to detect (bio-)geographical, spatial, and environmental effects

“…to monitor or experimentally manipulate benthic communities (Altman and Whitlatch, 2007;Bowden et al, 2006;Féral et al, 2016;Judge and Craig, 1997;Marraffini et al, 2017;Moura et al, 2008;Piola and Johnston, 2008;Sorte et al, 2010). Although artificial structures have already been used to compare biodiversity of marine hard bottoms from distinct geographical regions, the artificial substrates varied in size and material while colonization time, processing and analytical protocols were also different, making large-scale comparisons difficult to establish.…”

A united front against marine invaders: Developing a cost‐effective marine biosecurity surveillance partnership between government and industry

“…This included settlement arrays, crab traps, crab condos and shoreline surveillance. Each of these methods have been shown to be effective tools in IMP surveillance (Hewitt & McDonald, ; Marraffini, Ashton, Brown, Chang, & Ruiz, ; Tait & Inglis, ). For example, settlement arrays consist of a set of small plastic plates that provide vacant space upon which marine organisms can settle and grow (Figure ).…”