Humpback whale population demographics, reproductive physiology and consequences of disturbance
Humpback whales occupy every ocean in the world, and while the species experienced dramatic population decline in the 20th century due to whaling efforts, they have overall made an impressive recovery. However, both environmental and anthropogenic threats are still present. By studying population demographics, reproductive physiology, and population consequences of disturbances, we are better able to understand and predict species response to these threats.
Population demographics & reproductive physiology
To obtain population demographics, biopsied blubber samples were collected from Southern Hemisphere humpbacks within the feeding grounds. The molecular and endocrinological signatures derived from these samples are used to assess population demographics, such as sex ratio. The endocrine signatures (i.e. hormone concentrations) provide information on reproductive physiology, such as pregnancy state. In addition to the other demographic measures, population growth and calving rate are also being studied. Similarly, biopsied blubber samples were collected from the Hawaiian breeding ground of the North Pacific humpbacks. These samples will be used to assess the reproductive condition of this population.
Population consequences of disturbance
In order to understand population responses to disturbances, a stochastic dynamic programming model is being generated. The model uses information on short-term changes in individual behavior and physiology to detect long-term effects on population dynamics, which can then be used as a tool to effectively inform wildlife management and conservation strategies.
Southern Right Whale
Southern right whale movement and trophic ecology
The Southwestern Atlantic population of Southern Right whales (SRW) uses the coastal waters off Península Valdés in Argentina and Santa Catarina in Brazil as a winter nursery ground, where feeding is severely reduced. During late spring, SRW travel to unknown offshore feeding areas. To build the high energy reserves needed for migration and breeding activities, they require high-density patches of krill. Global warming is melting the Antarctic ice sheets where krill larvae feed, which could profoundly affect its predators. As biogeochemical markers, stable isotopes are used to explore how oceanographic parameters affect SRW feeding grounds’ ecosystem and how these fluctuations impact the whales’ migratory pattern and prey preferences.
For more information on this, take a look at the work Florencia Vilches is doing in the lab.
Minke whale population demographics and reproductive physiology and consequences of disturbance
There are currently two recognized species of minke whale, the common (or northern) minke Balaenoptera acutorostrata and the Antarctic minke Balaenoptera bonaerensis. Additionally, there is an unnamed subspecies of the common minke whale, the dwarf minke whale which is also common in the Southern ocean.Our research focuses on studying the population demographics and reproductive physiology of the lesser known Antarctic minke whale.
Population demographics & reproductive physiology
Remote skin-blubber biopsy samples are routinely collected from Antarctic minke whales along the Western Antarctic Peninsula during the austral summer. The molecular and endocrine signatures derived from these samples are used to assess population demographics, such as sex ratios as well as provide information on reproductive physiology, such as pregnancy state.
For more information, take a look at the work Logan Pallin is doing in the lab
Reproductive success of harbor porpoises in the face of disturbance
Harbor porpoises are a small cetacean species found throughout the world. Their small size leaves them with minimal energy reserves (blubber) for reproduction. These energy reserves may be further depleted by disturbance which can cause avoidance of critical feeding grounds and extra energy expenditure to travel away from the disturbance. A mathematical model (called a Stochastic Dynamic Programming model) is being constructed to assess how disturbance impacts the behavioral decisions of harbor porpoises and the subsequent alterations in body condition (a metric used to measure the available energy stores for reproduction) and reproductive success.
For more information on this, take a look at the work Stephanie Adamczak is doing in the lab.
Foraging and feeding behaviors
The resident common bottlenose dolphins (Tursiops truncatus) of Sarasota Bay, Florida, present a unique opportunity to validate and apply quantitative fatty acid signature analysis (QFASA), an innovative approach to assessing an animal’s diet. QFASA provides a months-long record of prey species proportions in predator diet, using the fact that prey fatty acids are deposited in predator blubber with minimal structural change. The diet information can be used to understand baseline diet variation between demographic groups, to monitor changes in feeding and foraging following large-scale environmental disturbances, such as harmful algal blooms, and to evaluate interactions between predators and fisheries.
For more information, take a look at the work Theresa-Anne Tatom-Naecker is doing in the lab.