Pbtx On Manatees

The potential effects of exposure to PbTX on manatees with CSS are not known. With increasing frequency and distribution of HABs, increasing diversity of predominant HAB species, and increasing CSS-related mortality in the northcentral GOM (Carmichael pers com.; Hieb et al. in prep.), it is important to understand the potential for combined effects of phycotoxin exposure and other natural stressor such as CSS. CSS may influence the absorption capacity for PbTX because constipation observed in CSS animals slows fecal evacuation rate, which may result in increased absorption and retention times of PbTX. The immune system suppression associated with PbTX exposure also may elicit symptomology following exposure in an immunocompromised cold-stressed

PbTX has been shown to act as developmental toxin (Kimm-Brinson and Ramsdell, 2001; Vasconcelos et al., 2010). Hence, pregnant females may experience pregnancy complications and calves or young adults may show impaired cognitive function, developmental deformities, or mortality. Impaired organ function or increased permeability of the blood brain barrier due to previous disease or natural aging also are considered to increase risk of morbidity following exposure to phycotoxin (Baden et al., 1982; Cheng et al., 2005; Pulido, 2008; Baron et al., 2013), such that older manatees may be at increased risk of mortality following exposure. Male individuals are thought to travel further distances while foraging and migrate further distances compared to the female counterparts (Fertl et al., 2005), which may preferentially increase risk of phycotoxin exposure by male manatees through

Samples from this study were taken from stranded animals that primarily died from natural CSS, which limited our ability to draw conclusions regarding the extent of exposure among the general population or normal healthy animals. Taking samples from decomposing animals and long-term storage times associated with using archived samples also may have affected the quality of the sample due to possible toxin loss. Additionally, while ELISA is a powerful and sensitive tool that can detect low-levels of toxins, it provides composite toxin levels, rather than a complete toxin profile. Due to differences in receptor affinity, and toxicity of metabolites or derivatives of the toxins, it can be difficult to truly understand the potential toxic burden from a composite test. Ideally, positive ELISA samples are confirmed by liquid chromatography tandem mass spectrometry (LCMS), which was not possible during this study. Additionally, other environmental toxins may be present, but were not detected due to the selective and highly specific nature of the assay used. Methods that affected toxin degradation or loss, however, should render findings more conservative, meaning the frequency and level of toxins present may have been higher in animals at time of death than determined in this