Friday, January 31, 2014

Selective Pressures Impact on Fisheries Management Reference Points

Fisheries management is a diverse field, essentially reliant on ecological reference points as proxies for fisheries stability and sustainability. Reference points are generally based on population dynamics such as maximum sustainable yield (MSY), spawning stock biomass (SSB), fishing mortality (F), and yield-per-recruit relationships among others. Heino et al (2013) defined fisheries-induced evolution (FIE) as a selective mechanism ,which can impact the stock population characteristics and life history traits through the shifting of reference points. Although it has been theorized that fisheries-induced evolution is taking place in various fish stocks, predominantly seen through reduced fish sizes, quantitative evidence for FIE actually occurring in the wild is still unavailable. Nonetheless, the authors conclude that reference points are shifting due to FIE, climate change, or other environmental and ecological factors, and emphasize that reference points must be re-evaluated and adjusted to be current and effective for fisheries management and conservation. – Hannah Tannenbaum

Heino, M. et al. 2013. Can Fisheries-induced Evolution shift Reference Points for Fisheries Management? ICES Journal of Marine Science 70, 707 – 721.

Wednesday, January 29, 2014

Maximizing the Storage Potential of Electric Vehicles in Smart Grids that are Increasingly Dependent on Renewable Energy Sources

 Large scale renewable energy projects, as well as small installments on houses and businesses, have the ability to transform the composition of energy sources that fuel society. While such sources are beneficial in reducing greenhouse gas emissions that result from power production, they provide new obstacles for the use and storage of energy. As renewable energy sources continue to produce larger quantities of energy, the electricity grid will have to adapt to this decentralized and unpredictable production. Ridder et al. (2013) examined the feasibility of charging electric vehicles (EVs) in a smart grid scenario and their ability to compensate for shortages and surpluses that occur in the energy market due to unpredictable energy supply. Utilizing behavioral information about the EV users, EV capacity, and the capacities of charging stations, the authors created a model to simulate EV potential in Flanders, Belgium. The coordination algorithm that was determined to fit the population resulted in the proper distribution of EVs amongst available charging stations so that capacity was maximized. In the second scenario, the authors demonstrated the ability of EV users to take advantage of varying prices of energy by strategically charging when excess day-ahead energy was available and selling energy back to the grid when demand exhausted supply and only day-of, or imbalance market energy was available. Ultimately, the study demonstrated that as imbalance market prices increased compared to day-ahead prices, flexible chargers were able to save money and charger/dischargers were able to make money by discharging energy at high market prices.—Stephanie Oehler

Ridder, F., D’Hulst, R., Knapen, L., Janssens, D., 2013. Applying an activity based model to explore the potential of electrical vehicles in the smart grid. Procedia Computer Science,847—853

Monday, January 27, 2014

Honeybees Exposed to Acetylcholinesterase Inhibitors Exhibit Impaired Motor Function

Stress from parasites, pathogens, and pesticides have been contributing to the global decline of populations of honeybees and many pollinators for the past two decades. Specifically, the use of pesticides that affect neuromuscular functioning and kill parasitic mites have caused the accumulation of acaricides, or mite pesticides, in the wax combs of bees’ hives. To investigate the possibility of this accumulation contributing to the decline of bee populations, Williamson et al. (2013) studied the effects of prolonged exposure to pesticides that inhibit acetylcholinesterase (AChE) on the physiology and behavior of bees. Adult worker bees were fed sub-lethal concentrations of four AChE inhibitors in sucrose solutions and then were observed for walking, stopped, grooming, and upside down behavior. After the behavioral study, the bees were dissected to confirm that the four compounds they assayed or their metabolites were responsible for the change in behavior by testing for transcript expression levels of two honeybee AChE inhibitors and through biochemical assays. All AChE inhibitors caused increased grooming behavior, but coumaphos in particular caused more grooming and symptoms of sickness as the concentration increased. The authors found that the effects of pesticides that inhibit AChE on the motor functioning of bees could reduce their survival and contribute to the decline of bee colonies. —Lia Metzger

                  Williamson, S.M., Moffat, C., Gomerall, M.A., Saranzewa, N., Connolly, C.N., Wright, G.A., 2013. Exposure to acetylcholinesterase inhibitors alters the physiology and motor function of honeybees. Frontiers in physiology 4.

Friday, January 24, 2014

The Past, Present and Potential Future Distributions of Cold-Adapted Bird Species

Population distribution models play an important role in analyzing past changes in species ranges and in projecting future adaptations in different species. Specifically, bird species provide important data regarding distribution adaptations because of they can more rapidly adjust to changes in climate than can non-flying species. Experimentally validating the accuracy of distributional models becomes important when such models are used to project future changes and such projections are used for policy decisions. Smith et al. 2013 tested the accuracy of climate-only distributional models by comparing model projections for four species of birds after the last glacial maximum (LGM) with the fossil records of the same species. These comparisons proved that two of the species of birds were in fact located at lower elevations during the LGM than they are today. Moreover, from this study it becomes evident that in the future, changes in climate may lead to the intersection of these bird species. From this study the authors conclude that climate-only projection models can accurately predict distribution changes. —Lizzie Medford

Smith, S., Gregory, R., Anderson, B., 2013. The past, present, and potential future distributions of cold-adapted bird
species. The Journal of Conservation Biology DOI 10.111/ddi. 12025.

Wednesday, January 22, 2014

Record of Contaminant Exposure Found in Blue Whale Earplug

The blue whale is the largest animal on earth and an Endangered Species.  The blue whale population has not only been affected by whaling activities but also by anthropogenic activities such as fishing entanglement, boat strikes, climate change and chemical emissions. Many of the resulting contaminants of the latter are found to reside in blubber and other lipid rich layers. Blue whales, and other large baleen whales, accumulate layers of earwax, known as cerumen, throughout their lifetimes. This wax builds up over time and produces dark and light colored layers, or laminae, which represent periods of feeding or migration. While early earplug analysis was used to age whales, it was recently discovered that it is possible to reconstruct lifetime profiles of hormones, mercury, and other pollutants. in whales.  Similar to blubber, these contaminants build up in the whale’s earplug in large enough concentrations to quantify. Tumble et al. (2013) looked at the earplug of a male blue whale to examine lifetime contaminant and hormonal profiles. They found 24 different laminae and estimated the whale’s age to be 12 years ± 6 months. Looking at the hormone levels, they were able to age the whale’s sexual maturity. When the contaminants were examined, it was found that much of the contaminants came from mother during the first 12 months. The mercury profiles showed peaks as a result of environmental and anthropogenic mercury increase. --Chloe Mayne

Trumble, S., Robinson, E., Berman-Kowalewski, M., Potter, C., Usenko, S., 2013. Blue whale earplug reveals lifetime contaminant exposure and hormone profiles. PNAS published ahead of print September 16, 2013,doi:10.1073/pnas.1311418110.

Monday, January 20, 2014

Patterns in Global, Regional, and Local Groundwater Depth

Up until this point, there has been no unifying effort to create a global map of groundwater tables.  However, a global, comprehensive map of the location and depth of water tables throughout the world can help with finding global patterns of groundwater movement.  Fan et al. compiled all existing government records of groundwater tables from over a million well sites around the globe.  Where government records were not available, they used data from published literature.  The compiled map was not complete though;  the water tables in many places around the globe remain unrecorded.  In order to look more closely and completely at global, regional, and local trends in groundwater distribution and depth the researchers also used a pre-existing groundwater table model.  They found that groundwater tends to be shallowest in the most humid climates, in wetland regions, in arid valleys and along the edges of continents, especially in areas with long, flat, plains of wetlands leading up to the coast.  Additionally, the model looked for the influence of three forces—climate, terrain, and sea level—on the water table depth (WTD).  While sea level has the strongest influence on WTD globally, regionally climate and topographic gradient are most important, and locally they found that terrain can override climate boundaries and lead to climatic anomalies like oases. —Alison Marks

Fan, Y., Li, H., Miguez-Macho, G. Global Patterns of Groundwater Table Depth.  Science 339, 940–943.

Friday, January 17, 2014

Population Growth in a Wild Bird is Buffered Against Phenological Mismatch

It is well understood that global climate change is having effects on various species, but there are few studies that have quantified the costs of sustained directional selection in response to global climate change.  Reed et al. conducted a study to test whether the population growth of Parus major (great tit) was negatively affected by climate change.  Specifically, to see if climate change induced a phenological mismatch.  They took four decades of individual level life history data from a population of great tits in the Netherlands whose breeding season is closely tied with the development of caterpillars as a food source to feed the young birds.  Caterpillar growth is closely linked to warm temperatures which are critical to the breeding success of the great tit.  Due to warmer springs there has been a mismatch of the breeding time and the food peak creating an intensification of direction selection to earlier laying dates.  This mismatch has not affected the population growth.  Reed et al. demonstrate a mechanism that contributes to the decoupling; that fitness losses due to the mismatch are countered by fitness gains due to less competition.  It implies that populations may be able to tolerate maladaptation from climate without immediately declining. Cameron Lukos

Reed, T.E., Grøtan, V., Jenouvrier, S., Sæther, B.-E., Visser, M.E., 2013. Population Growth in a Wild Bird Is Buffered Against Phenological Mismatch. Science 340, 488-491.