Benthic Herbivores are not Deterred by Brevetoxins

Authors: Erik E Sotka Amanda McCarty Emily A Monroe Nicole Oakman Frances M Van Dolah

Publish Date: 2009/07/11

Volume: 35, Issue: 7, Pages: 851-859

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Abstract

Gulf of Mexico blooms of the dinoflagellate Karenia brevis produce neurotoxic cyclic polyethers called brevetoxins During and after a red tide bloom in southwestern Florida K brevis cells lyse and release brevetoxins which then sink to the benthos and coat the surfaces of seagrasses and their epiphytes We tested the possibility that these brevetoxinladen foods alter the feeding behavior and fitness of a common benthic herbivore within Floridean seagrass beds the amphipod Ampithoe longimana We demonstrated that coating foods with K brevis extracts that contain brevetoxins at postbloom concentrations 1 μg g−1 drymass does not alter the feeding rates of Florida nor North Carolina populations of A longimana although a slight deterrent effect was found at eight and tenfold greater concentrations During a series of feeding choice assays A longimana tended not to be deterred by foods coated with K brevis extracts nor with the purified brevetoxins PbTx2 and PbTx3 Florida juveniles isolated with either extractcoated or control foods for 10 days did not differ in survivorship nor growth A similar lack of feeding response to brevetoxinladen foods also was exhibited by two other generalist herbivores of the southeastern United States the amphipod A valida and the urchin Arbacia punctulata Given that benthic mesograzers constitute a significant portion of the diet for the juvenile stage of many nearshore fishes we hypothesize that the ability of some mesograzers to feed on and retain brevetoxins in their bodies indicates that mesograzers may represent an important route of vertical transmission of brevetoxins through higher trophic levels within Gulf of Mexico estuariesWe thank Marie DeLorenzo Spencer Fire Hannah Giddens Tod Leighfield and Zhihong Wang for brevetoxin analyses fruitful discussion or both NO was supported by an NSF Research Experience for Undergraduates fellowship DBI0552828 and the Department of Defense ASSURE Program EES and AM were supported by a grant from NSF OCE0550245 This is Grice Marine Laboratory publication number 342 and NOAA CCEHBR CL1460 The National Ocean Service does not approve recommend or endorse any proprietary product or material mentioned in this publication

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