An assessment of the efficacy of chemical descalers for managing non-indigenous marine species within vessel internal seawater systems and niche areas

James Bracken,Nick Gust,Ashley Coutts,Jeff Ross

doi:10.3391/mbi.2016.7.3.04

Abstract

This study assessed the efficacy of commercially available descalers and factors that influence their efficacy as tools for marine biosecurity management. Laboratory experiments found calcium carbonate (CaCO 3 ) degradation varied up to 29% (from 111 to 143 g/l) amongst seven products tested. Increasing the concentration of hydrochloric, phosphoric and acid-surfactant descalers from 25 to 75% did not increase the rate or total degradation of the mussel, Mytilus planulatus. Warming descaling solutions (from 11 to 26°C) significantly increased the rate of mussel mortality, decay and total degradation in all treatments. Circulating treatments increased mussel mortality and decay rate in hydrochloric and acid-surfactant descalers, but had no detectable effect on total degradation after 24h. Hydrochloric acid based descalers (Rydlyme®, 3H® and Dynamic Descaler®) were more effective than phosphoric acid (Barnacle Buster®) and acid-surfactant (Triple 7 Enviroscale Plus®) treatments. Organic material was largely resistant to degradation under all treatments. The implications for descalers as marine biosecurity tools are discussed.

Highlights

Acanthaster planci (Linnaeus, 1758), the crown-ofthorns seastar, are voracious, opportunistic carnivores that typically consume sessile invertebrates, hard corals, and carrion
One lesson from invasion ecology readily applied to A. planci is the understanding of critical stages in life-history to inform cost-effective management actions and determine outbreak triggers (Pratchett et al 2014)
The long term prospects for the Great Barrier Reef are of concern without a dedicated long-term framework to target the higher risk, quick return impacts affecting coral cover during A. planci boom periods as well as monitoring and understanding the conditions needed to support bust cycles

Summary

Introduction

Acanthaster planci (Linnaeus, 1758), the crown-ofthorns seastar, are voracious, opportunistic carnivores that typically consume sessile invertebrates, hard corals, and carrion. A. planci has exhibited long-term boom-bust population cycles to devastating effect in the Indo-Pacific, threatening the Great Barrier Reef (e.g., Uthicke et al 2009; Baird et al 2013). On the Great Barrier Reef there have been four documented A. planci outbreaks since the 1960’s, each spaced ~17 years apart (Pratchett et al 2014). During these outbreaks natural densities increase to a point resulting in “plagues” of the seastar consuming coral faster than it can grow.

Methods

Results

Conclusion