Potent marine neurotoxins known as brevetoxins are produced by the 'red tide' dinoflagellate Karenia brevis. They kill large numbers of fish and cause illness in humans who ingest toxic filter-feeding shellfish or inhale toxic aerosols 1 . The toxins are also suspected of having been involved in events in which many manatees and dolphins died, but this has usually not been verified owing to limited confirmation of toxin exposure, unexplained intoxication mechanisms and complicating pathologies 2-4 . Here we show that fish and seagrass can accumulate high concentrations of brevetoxins and that these have acted as toxin vectors during recent deaths of dolphins and manatees, respectively. Our results challenge claims that the deleterious effects of a brevetoxin on fish (ichthyotoxicity) preclude its accumulation in live fish, and they reveal a new vector mechanism for brevetoxin spread through food webs that poses a threat to upper trophic levels.In the spring of 2002, 34 endangered Florida manatees (Trichechus manatus latirostris) died in southwest Florida, and 107 bottlenose dolphins (Tursiops truncatus) died in waters off the Florida panhandle in the spring of 2004. In both of these unusual mortality events, extensive water surveys revealed that only low concentrations of K. brevis were present.We tested for the presence of brevetoxin in the fluids and tissues of 63 of these animals (27 manatees, 36 dolphins) and found very high concentrations in the tissues of all of them (see Supplementary information accompanies this communication on Nature's website.

DRAFT -DO NOT CITE OR CIRCULATE. Page 2 2 Abstract 22 23Protracted entanglement in fishing gear often leads to emaciation through reduced 24 mobility and foraging ability, and energy budget depletion from the added drag of towing 25 gear for months or years. We examined changes in kinematics of a tagged entangled 26North Atlantic right whale (Eg 3911), before, during and after disentanglement on 15 Jan 27 2011. To calculate the additional drag forces and energetic demand associated with 28 various gear configurations, we towed three sets of gear attached to a load-cell 29 tensiometer at multiple speeds. Tag analyses revealed significant increases in dive depth 30 and duration; ascent, descent and fluke stroke rates; and decreases in root mean square 31 fluke amplitude (a proxy for thrust) following disentanglement. Conservative drag 32 coefficients while entangled in all gear configurations (mean±SD C d,e,go = 3.4x10 -3 ± 33 0.0003, C d,e,gb = 3.7x10 -3 ± 0.0003, C d,e,sl = 3.8x10 -3 ± 0.0004) were significantly greater 34 than in the nonentangled case (C d,n = 3.2x10 -3 ±0.0003; P = 0.0156, 0.0312, 0.0078 35 respectively). Increases in total power input (including standard metabolism) over the 36 nonentangled condition ranged 1.6%-120.9% for all gear configurations tested; 37 locomotory power requirements increased 60.0%-164.6%. These results highlight 38 significant alteration to swimming patterns, and the magnitude of energy depletion in a 39 chronically entangled whale. 40 41

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Between 1993 and 2003, 713 (24%) of 2,940 dead Florida manatees (Trichechus manatus latirostris) recovered from Florida waters and examined were killed by watercraft-induced trauma. It was determined that this mortality was the result of watercraft trauma because the external wound patterns and the internal lesions seen during gross necropsy are recognizable and diagnostic. This study documents the methods used in determining watercraft-related mortality during gross necropsy and explains why these findings are diagnostic. Watercraft can inflict sharp- and blunt-force trauma to manatees, and both types of trauma can lead to mortality. This mortality may be a direct result of the sharp and blunt forces or from the chronic effects resulting from either force. In cases in which death is caused by a chronic wound-related complication, the original incident is usually considered to be the cause of death. Once a cause of death is determined, it is recorded in an extensive database and is used by Federal and state managers in developing strategies for the conservation of the manatee. Common sequelae to watercraft-induced trauma include skin lesions, torn muscles, fractured and luxated bones, lacerated internal organs, hemothorax, pneumothorax, pyothorax, hydrothorax, abdominal hemorrhage and ascites, and pyoperitoneum.

Watercraft‐related mortality represents 1,253 (24.9%) of 5,033 Florida manatee (Trichechus manatus latirostris) deaths recorded between 1 January 1979 and 31 December 2004. Wound patterns generated by collisions with watercraft are diagnostic. Sets of cuts and scrapes that are roughly equidistant and perpendicular to the direction of vessel travel are consistent with lacerations made by propeller blades. From these lesions, estimates of propeller diameter, pitch, rotation, and direction of travel may be obtained. Considerable overlap of propeller sizes and pitches on different size vessels, common use of counter rotation propellers, and numerous other complicating factors may confound efforts to accurately predict vessel size and type from propeller wounds. Of the more than one million watercraft registered in Florida, 98% are ≤12.2 m (40 ft), yet watercraft 5.3–36.6 m (17.5–120 ft) are known to have killed manatees. Analysis of a 5‐yr subset of mortality data suggests that a disproportionate number of propeller‐caused watercraft‐related mortalities could be attributed to propeller diameters ≥43.2 cm (17 in.), inferring that these were caused by watercraft ≥12.2 m (40 ft).