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

Hippopotamus and livestock grazing:influences on riparian vegetation and facilitation of other herbivores in the Mara Region of Kenya

<p>Riparian savanna habitats grazed by hippopotamus or livestock experience seasonal ecological stresses through the depletion of herbaceous vegetation, and are often points of contacts and conflicts between herbivores, humans and their livestock. We investigated how hippopotamus and livestock grazing influence vegetation structure and cover and facilitate other wild herbivores in the Mara region of Kenya. We used 5 km-long transects, each with 13 plots measuring 10 x 10 m(2), and which radiate from rivers in the Masai Mara National Reserve and adjoining community pastoral ranches. For each plot, we measured the height and visually estimated the percent cover of grasses, forbs, shrubs and bare ground, herbivore abundance and species richness. Our results showed that grass height was shortest closest to rivers in both landscapes, increased with increasing distance from rivers in the reserve, but was uniformly short in the pastoral ranches. Shifting mosaics of short grass lawns interspersed with patches of medium to tall grasses occurred within 2.5 km of the rivers in the reserve in areas grazed habitually by hippos. Hence, hippo grazing enhanced the structural heterogeneity of vegetation but livestock grazing had a homogenizing effect in the pastoral ranches. The distribution of biomass and the species richness of other ungulates with distance from rivers followed a quadratic pattern in the reserve, suggesting that hippopotamus grazing attracted more herbivores to the vegetation patches at intermediate distances from rivers in the reserve. However, the distribution of biomass and the species richness of other ungulates followed a linear pattern in the pastoral ranches, implying that herbivores avoided areas grazed heavily by livestock in the pastoral ranches, especially near rivers.</p>

Survey of Borreliae in ticks, canines, and white-tailed deer from Arkansas, U.S.A.

<p>Abstract</p> <p>Background</p> <p>In the Eastern and Upper Midwestern regions of North America, <it>Ixodes scapularis</it> (L.) is the most abundant tick species encountered by humans and the primary vector of <it>B. burgdorferi,</it> whereas in the southeastern region <it>Amblyomma americanum</it> (Say) is the most abundant tick species encountered by humans but cannot transmit <it>B. burgdorferi.</it> Surveys of Borreliae in ticks have been conducted in the southeastern United States and often these surveys identify <it>B. lonestari</it> as the primary <it>Borrelia</it> species, surveys have not included Arkansas ticks, canines, or white-tailed deer and <it>B. lonestari</it> is not considered pathogenic. The objective of this study was to identify <it>Borrelia</it> species within Arkansas by screening ticks (n = 2123), canines (n = 173), and white-tailed deer (n = 228) to determine the identity and locations of Borreliae endemic to Arkansas using PCR amplification of the flagellin (<it>flaB)</it> gene.</p> <p>Methods</p> <p>Field collected ticks from canines and from hunter-killed white-tailed were identified to species and life stage. After which, ticks and their hosts were screened for the presence of <it>Borrelia</it> using PCR to amplify the <it>flaB</it> gene. A subset of the positive samples was confirmed with bidirectional sequencing.</p> <p>Results</p> <p>In total 53 (21.2%) white-tailed deer, ten (6%) canines, and 583 (27.5%) Ixodid ticks (252 <it>Ixodes scapularis</it>, 161 <it>A. americanum</it>, 88 <it>Rhipicephalus sanguineus</it>, 50 <it>Amblyomma maculatum,</it> 19 <it>Dermacentor variabilis,</it> and 13 unidentified <it>Amblyomma</it> species) produced a <it>Borrelia flaB</it> amplicon. Of the positive ticks, 324 (22.7%) were collected from canines (151 <it>A. americanum,</it> 78 <it>R. sanguineus</it>, 43 <it>I. scapularis,</it> 26 <it>A. maculatum,</it> 18 <it>D. variabilis</it>, and 8 <it>Amblyomma</it> species) and 259 (37.2%) were collected from white-tailed deer (209 <it>I. scapularis,</it> 24 <it>A. maculatum,</it> 10 <it>A. americanum,</it> 10 <it>R. sanguineus</it>, 1 <it>D. variabilis</it>, and 5 <it>Amblyomma</it> species). None of the larvae were PCR positive. A majority of the <it>flaB</it> amplicons were homologous with <it>B. lonestari</it> sequences: 281 of the 296 sequenced ticks, 3 canines, and 27 deer. Only 22 deer, 7 canines, and 15 tick <it>flaB</it> amplicons (12 <it>I. scapularis</it>, 2 <it>A. maculatum</it>, and 1 <it>Amblyomma</it> species) were homologous with <it>B. burgdorferi</it> sequences.</p> <p>Conclusions</p> <p>Data from this study identified multiple Borreliae genotypes in Arkansas ticks, canines and deer including <it>B. burgdorferi</it> and <it>B. lonestari;</it> however, <it>B. lonestari</it> was significantly more prevalent in the tick population than <it>B. burgdorferi</it>. Results from this study suggest that the majority of tick-borne diseases in Arkansas are not <it>B. burgdorferi.</it></p

Polyploidy and its effect on evolutionary success: old questions revisited with new tools

Polyploidy, the condition of possessing more than two complete genomes in a cell, has intrigued biologists for almost a century. Polyploidy is found in many plants and some animal species and today we know that polyploidy has had a role in the evolution of all angiosperms. Despite its widespread occurrence, the direct effect of polyploidy on evolutionary success of a species is still largely unknown. Over the years many attractive hypotheses have been proposed in an attempt to assign functionality to the increased content of a duplicated genome. Among these hypotheses are the proposal that genome doubling confers distinct advantages to a polyploid and that these advantages allow polyploids to thrive in environments that pose challenges to the polyploid's diploid progenitors. This article revisits these long-standing questions and explores how the integration of recent genomic developments with ecological, physiological and evolutionary perspectives has contributed to addressing unresolved problems about the role of polyploidy. Although unsatisfactory, the current conclusion has to be that despite significant progress, there still isn't enough information to unequivocally answer many unresolved questions about cause and effect of polyploidy on evolutionary success of a species. There is, however, reason to believe that the increasingly integrative approaches discussed here should allow us in the future to make more direct connections between the effects of polyploidy on the genome and the responses this condition elicits from the organism living in its natural environment