Effects of a bacteria-produced algicide on non-target marine invertebrate species

Victoria E Simons,Kathryn J Coyne,Jonathan H Cohen,Mark E Warner,Margaret M Dolan

doi:10.1038/s41598-020-79814-w

Victoria E Simons, Kathryn J Coyne + Show 3 more

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https://doi.org/10.1038/s41598-020-79814-w

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Journal: Scientific Reports	Publication Date: Jan 12, 2021
Citations: 3	License type: open-access

Affiliation: University of Delaware

Abstract

Harmful algal blooms (HABs) affect both freshwater and marine systems. Laboratory experiments suggest an exudate produced by the bacterium Shewanella sp. IRI-160 could be used to prevent or mitigate dinoflagellate blooms; however, effects on non-target organisms are unknown. The algicide (IRI-160AA) was tested on various ontogenetic stages of the copepod Acartia tonsa (nauplii and adult copepodites), the blue crab Callinectes sapidus (zoea larvae and megalopa postlarvae), and the eastern oyster Crassostrea virginica (pediveliger larvae and adults). Mortality experiments with A. tonsa revealed that the 24-h LC50 was 13.4% v/v algicide for adult females and 5.96% for early-stage nauplii. For C. sapidus, the 24-h LC50 for first-stage zoeae was 16.8%; results were not significant for megalopae or oysters. Respiration rates for copepod nauplii increased in the 11% concentration, and in the 11% and 17% concentrations for crab zoeae; rates of later stages and oysters were unaffected. Activity level was affected for crab zoeae in the 1%, 11%, and 17% treatments, and for oyster pediveliger larvae at the 17% level. Activity of later stages and of adult copepods was unaffected. Smaller, non-target biota with higher surface to volume could be negatively impacted from IRI-160AA dosing, but overall the taxa and stages assayed were tolerant to the algicide at concentrations required for dinoflagellate mortality (EC50 = ~ 1%).

Highlights

Harmful algal blooms (HABs) affect both freshwater and marine systems
Megalopae proved far more resistant to the algicide: no treatments had greater than 10% mortality, even after 48 h of exposure, we could not calculate an LC50 (Fig. 1d)
We examined both pumping and grooming of the egg mass in ovigerous female C. sapidus when exposed to homogenized eggs with and without algicide

Summary

Introduction

Harmful algal blooms (HABs) affect both freshwater and marine systems. Laboratory experiments suggest an exudate produced by the bacterium Shewanella sp. IRI-160 could be used to prevent or mitigate dinoflagellate blooms; effects on non-target organisms are unknown. With harmful algal blooms comes the bioavailability of harmful compounds these algae produce; in Delaware, USA, blooms of harmful algae including Karlodinium veneficum have been r eported[6], with K. veneficum producing karlotoxins responsible for hemolytic, cytotoxic, and ichthyotoxic effects[7] These toxins create pores in cellular membranes that disrupt ion gradients, leading to lysis and fish k ills[8,9] and negative effects on invertebrates[10,11]. While the algicidal compound(s) have yet to be fully isolated[28], an alternative approach is to determine how the whole bacterial exudate may affect non-target species[23,24,25,26,27]. A similar approach with IRI-160AA was recently tested at lower trophic levels: after exposing a planktonic community to the algicide, Tilney et al.[26] noted an increase in heterotrophic protists and a bactivorous

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