An active subglacial water system in West Antarctica mapped from space

Satellite laser altimeter elevation profiles from 2003 to 2006 collected over the lower parts of Whillans and Mercer ice streams, West Antarctica, reveal 14 regions of temporally varying elevation, which we interpret as the surface expression of subglacial water movement. Vertical motion and spatial extent of two of the largest regions are confirmed by satellite image differencing. A major, previously unknown subglacial lake near the grounding line of Whillans Ice Stream is observed to drain 2.0 cubic kilometers of water into the ocean over approximately 3 years, while elsewhere a similar volume of water is being stored subglacially. These observations reveal a wide spread, dynamic subglacial water system that may exert an important control on ice flow and mass balance.     

Antibacterial activity of marine and black band disease cyanobacteria against coral-associated bacteria

Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of BBD cyanobacteria, and ten strains of cyanobacteria isolated from other marine sources, for their antibacterial effect on growth of heterotrophic bacteria isolated from BBD, from the surface mucopolysaccharide layer (SML) of healthy corals, and three known bacterial coral pathogens. Assays were conducted using two methods: co-cultivation of cyanobacterial and bacterial isolates, and exposure of test bacteria to (hydrophilic and lipophilic) cyanobacterial cell extracts. During co-cultivation, 15 of the 20 cyanobacterial strains tested had antibacterial activity against at least one of the test bacterial strains. Inhibition was significantly higher for BBD cyanobacteria when compared to other marine cyanobacteria. Lipophilic extracts were more active than co-cultivation (extracts of 18 of the 20 strains were active) while hydrophilic extracts had very limited activity. In some cases co-cultivation resulted in stimulation of BBD and SML bacterial growth. Our results suggest that BBD cyanobacteria are involved in structuring the complex polymicrobial BBD microbial community by production of antimicrobial compounds.     

Confounded winter and spring phenoclimatology on large herbivore ranges

Annual variation in winter severity and growing season vegetation dynamics appear to influence the demography of temperate herbivores but parsing winter from spring effects requires independent metrics of environmental conditions specific to each season. We tested for independence in annual variation amongst four common metrics used to describe winter severity and early growing season vegetation dynamics across the entire spatial distribution of elk (Cervus elaphus) in Wyoming from 1989 to 2006. Winter conditions and early growing season dynamics were correlated in a specific way. Winters with snow cover that ended early tended to be followed by early, but slow, rises in the normalized difference vegetation index (NDVI), while long winters with extended periods of snow cover were often followed by late and rapid rises in NDVI. Across the 35 elk ranges, 0.4–86.8 % of the variation in the rate of increase in NDVI’s in spring was explained by the date snow cover disappeared from SNOTEL stations. Because phenoclimatological metrics are correlated across seasons and shifting due to climate change, identifying environmental constraints on herbivore fitness, particularly migratory species, is more difficult than previously recognized.     

Biliary Cystadenoma in a Rabbit (Oryctolagus cuniculus)

Biliary tumors are rarely diagnosed in rabbits, and there are very few published case reports of this disease within this group of animals. This case involves an approximately 6-year-old spayed female pet rabbit that was referred for an abdominal mass noted on survey full-body radiographs obtained during an examination after presenting for acute onset anorexia. Otherwise, the patient had an unremarkable history, and physical examination abnormalities were limited to a slightly distended abdomen. Laboratory evaluation revealed an isolated elevation in gamma-glutamyl transpeptidase. Ultrasonography documented a 5.4-cm multicystic, intrahepatic mass with hyperechoic septations. The mass was surgically resected and described histopathologically as a proliferation of ectatic duct structures with a simple epithelial lining, supporting a diagnosis of biliary cystadenoma. The rabbit recovered without incident and was doing well 15 months postsurgery. The case is presented with a review of all reported cases and discussion of the potential origins of this unusual tumor in the rabbit. Surgery is recommended in rabbits that are diagnosed with a biliary tumor.     

Acceptability of Teff Hay by Horses

Teff (Eragrostis tef) is a productive warm season annual grass. Because teff is relatively new to the horse industry in the United States, horses unaccustomed to teff hay were used in two sets of two-choice preference tests comparing teff with alfalfa hay or teff with timothy hay. A second experiment used mature mares to compare voluntary dry matter intake (VDMI) of teff hay and timothy hay. In the two-choice preference tests, horses preferred alfalfa hay and timothy hay to teff hay (P < .05). Horses preferred teff hay that was cut at an earlier stage of maturity and had lower concentrations of neutral detergent fiber and acid detergent fiber than teff hay cut at a later stage of maturity. In the VDMI experiment, four mares were fed teff hay and four mares were fed timothy hay for 17 days. Both hays had been harvested in the head stage of maturity. VDMI was measured during the last 10 days and was not different between the two groups of horses (P > .05). It was concluded that horses that are unfamiliar with teff may discriminate against it when it is offered simultaneously with alfalfa or timothy; however, if not given a choice, horses will consume approximately the same amount of mature teff as mature timothy. Additional studies are needed to compare VDMI of early maturity teff hay with other common hays.