Effects of brown tide (Aureococcus anophagefferens) on hard clam, Mercenaria mercenaria, larvae and implications for benthic recruitment

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DOIResolve DOI: http://doi.org/10.3354/meps331147
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TypeArticle
Journal titleMarine Ecology Progress Series
Volume331
Pages147159; # of pages: 13
Subjectbrown tide; Aureococcus anophagefferens; clam larvae; Mercenaria mercenaria; algal blooms; cell culture; cell size; dietary supplements; diets; bivalvia; digestive tract; feed composition; feeding; feeding experiments; food; grazing; growth rate; larval development; marine aquaculture; mortality causes; mortality factors; nutrient deficiency; nutrition; phytoplankton; plankton; spawning; suspension; tides; Isochrysis galbana
AbstractBrown tides of Aureococcus anophagefferens occur in shallow mid-Atlantic bays in the USA and attain peak summer densities of ~1000 to 2800 cells µl–1. Blooms coincide with the period of spawning and planktotrophic larval development of the hard clam Mercenaria mercenaria, a commercially important bivalve in the region. This laboratory study investigates the effects of A. anophagefferens (toxic isolate from Provasoli-Guillard Center for Culture of Marine Phytoplankton [CCMP 1708]) on hard clams throughout their larval development as a function of increasing (1) supplement and (2) contributor to total phytoplankton cell volume in the diet. Brown tide consistently inhibited veliger growth rates in a dose-dependent manner, leading to arrested development in the D-stage; yet mortalities varied greatly among larval batches and were attributed to secondary effects of nutritional stress. Growth of larvae exposed for 2 wk to brown tide at 800 cells µl–1 was 89 to 90% less than controls fed Isochrysis galbana (clone T-iso) in both the presence and absence of alternate food. No recovery was observed when larvae were returned to the control diet. However, larvae showed variable intrapopulation susceptibility to brown tide when exposed to a mixed suspension of A. anophagefferens and I. galbana (400 and 50 cells µl–1, respectively). Exposure to low levels of brown tide (50 cells µl–1) resulted in relatively small but significant growth reduction. Larvae had reduced larval clearance rates (ingestion) when exposed to unialgal brown tide, as confirmed by analysis of gut autofluorescence and negative feeding selectivity for A. anophagefferens in a mixed suspension. Therefore, primarily through their inhibitory effects on growth, brown tides at ?200 cells µl–1 are expected to cause metamorphic failure of hard clam larval populations. These will lead to extended larval life in the plankton and increased vulnerability to secondary mortality factors. In turn, hard clam larvae are expected to make a negligible contribution to microzooplankton grazing on brown tide.
Publication date
PublisherInter-Research
Copyright notice© Inter-Research 2007 · www.int-res.com Resale or republication not permitted without written consent of the publisher
LanguageEnglish
AffiliationNRC Institute for Marine Biosciences; National Research Council Canada; Aquatic and Crop Resource Development
Peer reviewedYes
IdentifierNRC-ACRD-55894
NRC number1216
NPARC number3538508
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Record identifiera1703ef5-6379-4fdc-9f0e-1188dad36b3a
Record created2009-03-01
Record modified2016-05-09
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