51·çÁ÷¹ÙÍø

Project Description

This laboratory-based study will validate blubber steroid analysis in 3 species of large whales, 2 mysticetes and 1 odontocete. The development and validation will take 2 forms, analytical and biological. The analytical validation is comprised of standard laboratory methods that are commonly used and referred to by endocrine journals as the baseline for validating immunoassays. To initiate the biological validation, humpback whale (Megaptera novaeangliae) tissues will be analyzed along the dorsal and ventrolateral axis of the body as well as in depth of the blubber layer to determine how much variability exists with an individual whale depending on the location and depth that the sample comes from. The biological validation will continue by comparing measured concentrations between sexes, known life history stages (immature vs. mature) and reproductive classes (pregnant vs. non-pregnant) using archived tissues from humpback whales, blue whales (Balaenoptera musculus) and opportunistically false killer whales (Pseudorca crassidens). The validated assays will be used to analyze stress and reproductive hormones to compare physiological function relative to proximity to anthropogenic disturbances such as noise. Without extensive knowledge of an animal's physiology, such as reproductive cycles, it is difficult to discriminate between normal fluctuations in hormones and the impact that an anthropogenic disturbance may have on an animal's ability to reproduce and maintain homeostasis. This lack of data and information on external stressors, physiology and trends in abundance, reduces the ability to effectively manage for the recovery of large whale species, especially those listed under the Endangered Species Act (ESA). Advancements in endocrinological techniques have allowed researchers to measure hormones in minute concentrations, in a variety of biological media (serum, saliva, urine, feces and blubber). Glucocorticoids, such as cortisol and corticosterone, are steroid hormones that are relatively stable, and are able to be measured in a variety of biological media. Progesterone, typically viewed as the primary hormone of pregnancy maintenance, is probably the most commonly measured steroid in cetaceans. Its diagnostic use in differentiating age groups and reproductive status assists with management of captive dolphins and whales and, in free-ranging cetaceans, its measurement can be used to ascertain the onset of sexual maturity, reproductive cycles, and/or pregnancy. Using these hormones, this study will promote the use of endocrine techniques to advance our knowledge of the physiology of cetaceans.

Project Funding

Office of Naval Research
Start Date: 2014-06-00
End Date: 2016-05-00

 

 

Research Team