Concurrent Exposure of Bottlenose Dolphins (Tursiops truncatus) to Multiple Algal Toxins in Sarasota Bay, Florida, USA

Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000–2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e., DA: 2004, 2005, 2006, 2008, 2009; brevetoxin: 2000, 2004, 2005, 2008, 2009) with 36% of all animals testing positive for brevetoxin (n = 118) and 53% positive for DA (n = 83) with several individuals (14%) testing positive for both neurotoxins in at least one tissue/fluid. To date there have been no previously published reports of DA in southwestern Florida marine mammals, however the May 2008 health assessment coincided with a Pseudo-nitzschia pseudodelicatissima bloom that was the likely source of DA observed in seawater and live dolphin samples. Concurrently, both DA and brevetoxin were observed in common prey fish. Although no Pseudo-nitzschia bloom was identified the following year, DA was identified in seawater, fish, sediment, snails, and dolphins. DA concentrations in feces were positively correlated with hematologic parameters including an increase in total white blood cell (p = 0.001) and eosinophil (p<0.001) counts. Our findings demonstrate that dolphins within Sarasota Bay are commonly exposed to two algal toxins, and provide the impetus to further explore the potential long-term impacts on bottlenose dolphin health

Efficacy of fungicides on mycelial growth of diatrypaceous fungi associated with grapevine trunk disease

Several species of Diatrypaceae have been recently isolated from the wood of cankered grapevines in several regions of the world and shown to be pathogenic with varying degrees of virulence when inoculated in stems of potted vines. Existing management strategies have focussed on the evelopment of procedures and products to prevent or reduce Eutypa lata infection. The best method to prevent infection is by applying fungicides to wounds, but there are few registered chemicals for any of the diatrypaceous fungi in Australia. Six selected fungicides were evaluated in vitro for their efficacy in reducing mycelial growth of Eutypa lata, Cryptovalsa ampelina, Diatrypella vulgaris, Eutypa leptoplaca, Eutypella citricola and Eutypella microtheca. Carbendazim, fluazinam, tebuconazole, and prothioconazole + tebuconazole were effective at inhibiting mycelial growth of all Diatrypaceae spp. tested. Pyraclostrobin reduced colony diameter of most of the fungal species by 50% or more. Pyrimethanil was ineffective at reducing mycelial growth of these pathogens. Five of the six fungicides evaluated in this study have shown efficacy in vitro against Diatrypaceae spp. and require further evaluation in the field. This study represents the first approach for fungicide evaluation against mycelial growth of diatrypaceous fungi, other than Ea. lata. It contributes to the development of integrated management strategies for grapevine trunk diseases. © 2011 Australasian Plant Pathology Society Inc.Peer Reviewe