Place A.R.,University of Maryland, Baltimore |
Bowers H.A.,University of Maryland, Baltimore |
Bachvaroff T.R.,University of Maryland, Baltimore |
Adolf J.E.,University of Maryland, Baltimore |
And 2 more authors.
Harmful Algae | Year: 2012
For decades, high densities of the dinoflagellate Karlodinium veneficum have been associated with aquatic faunal mortalities worldwide. This small (<8-12μm) athecate phytoplankton, common in coastal aquatic ecosystems, has a mixed nutritional mode, relying on both photosynthesis and phagotrophy for growth (mixotrophy). It is frequently present in relatively low cell abundance (10 2-10 3cellsmL -1), but is capable of forming intense blooms of 10 4-10 5cellsmL -1 that are often associated with fish kills. A suite of toxic compounds (karlotoxins) have been characterized, both in the laboratory and in the field, with hemolytic, ichthyotoxic, and cytotoxic properties. These toxins have been shown to generate pores in membranes with desmethyl sterols and increase the ionic permeability resulting in membrane depolarization, disruption of motor functions, osmotic cell swelling and lysis. The biological raison d'etre for karlotoxin production appears to be prey capture but grazing deterrence is an additional advantage. Strain variation in types of karlotoxins and toxin cell quotas is extensive. Since its initial description in 1956 by Dorothy Ballentine toxic and nontoxic strains are common. Despite numerous name changes it is now clearly recognized as a cosmopolitan species with extensive ecosystem impacts. © 2011 Elsevier B.V.
PubMed | Us Fda Washington Seafood Laboratory and University of Maryland, Baltimore
Type: | Journal: Harmful algae | Year: 2016
Ichthyotoxic Karlodinium veneficum has become a persistent problem in the eutrophic Swan River Estuary (SRE) near Perth, Western Australia. Karlotoxin (KmTx) concentrations and K. veneficum were sampled from March to July 2005, spanning a bloom confirmed by microscopy and genetics (ITS sequence), and a fish kill coincident with end of the bloom. The objective of this study was to investigate K. veneficum cell and toxin dynamics, and water quality conditions, leading up to the bloom and fish kill in this estuarine system. Abundance of K. veneficum increased as diatom abundance decreased over a 3-month period (Jan-Mar) preceding the bloom. Low freshwater flow to the SRE characterized the bloom initiation period, while elevated seasonal flows altered water quality and preceded the end of the bloom and fish kill. The bloom of K. veneficum was localized over a bottom layer of hypoxic water in a stratified water column. Low nitrate levels, DIN:DIP (mol) near unity, and particulate C:N:P of K. veneficum-rich water samples were consistent with nitrogen limitation of phytoplankton. A KmTx 2 congener was present in the concentration range 0-1052 ng KmTx mL