White-Nose Syndrome has been linked to unprecedented morbidity and mortality among five of the nine species of bats in the northeastern United States, first observed in six hibernacula in New York State in the winter of 2006-2007, and subsequently reported from at least 33 caves and mines in four states (New York, Vermont, Massachusetts, and Connecticut) in the winter of 2007-2008, with mortality reported as high as 95% at some sites. The hypothesis being tested is that a reduction in the quantity and quality fat deposited by bats during the pre-hibernation period in autumn may compromise successful hibernation, and their ultimate reproductive success. White adipose tissue (WAT) is the primary source of energy that sustains bats (and other hibernators) throughout the winter when they have no access to food. Over-winter survival and subsequent reproductive success requires a sufficient quantity and quality of WAT deposited during the pre-hibernation period, and sufficient fat reserves to sustain deep torpor and periodic arousals throughout the winter, and a final arousal in spring. Because insectivorous bats cannot synthesize polyunsaturated fatty acids (PUFAs), deficiencies in dietary PUFAs during the pre-hibernation period in autumn may reduce the duration and depth of torpor during hibernation. Frequent arousals during hibernation may result in premature depletion of WAT before the end of the hibernation period. Moreover, depleted WAT at this time may contribute to a decrease in leptin production (necessary for ovulation and successful reproduction by females), or, in the worst cases, the inability to arouse from torpor or inability to mount an immune response to possible pathogens.
Analyses of body composition (including PUFAs) of bats of little brown myotis (Myotis lucifugus) during the pre-hibernation period will be conducted at sites affected by and unaffected by WNS to test three hypotheses that may help reveal or rule out causes of premature deaths or compromise reproductive success in these hibernating bats. Body composition analysis provides the most accurate and reliable estimates of total body water, WAT, and lean dry mass, and analyses of PUFAs in WAT collected from bats during the pre-hibernation fattening period. These data promise to provide valuable insight for testing proposed hypotheses to help explain why hibernating bats are dying prematurely at hibernacula in the northeastern US, and in turn suggest directions for future study to better understand WNS.
The proposed research will facilitate cross-disciplinary research between an ecologist, biochemical ecologist, and an endocrinologist to address an urgent environmental problem: unexpected mortality in hibernating insectivorous bats in the northeastern US. The proposed research will provide new insight into the mechanisms that influence winter survival and reproductive success in bats. Moreover, this research will provide an excellent opportunity to highlight the ecological and economic importance of bats in temperate ecosystems through print media, radio, TV, and web-based Internet blogs.
