Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)

Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.     

Radionuclides in deer and elk from Los Alamos National Laboratory and the doses to humans from the ingestion of muscle and bone.

This paper summarizes radionuclide concentrations (3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p < 0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% of LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y-1 (2.2 microSv y-1), deer bone = 3.8 mrem y-1 (38 microSv y-1), elk muscle = 0.12 mrem y-1 (1.2 microSv y-1), and elk bone = 1.7 mrem y-1 (17 microSv y-1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y-1 (1000 microSv y-1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E-06, which is far below the Environmental Protection Agency upper level guideline of 1E-04.     

Eusociality has evolved independently in two genera of bathyergid mole-rats — but occurs in no other subterranean mammal

Summary Extensive field and laboratory studies show that Damaraland mole-rats, like naked mole-rats, have an extreme form of vertebrate sociality. Colonies usually contain 2 reproductives and up to 39 non-breeding siblings, 90% of whom live a socially-induced lifetime of sterility; they remain in the natal colony, forage for food, defend the colony and care for successive litters. Although there is heightened dispersal following good rainfall, the majority of adult non-reproductives remain in their natal colony and failure to disperse is not directly attributable to habitat saturation or unfavourable soil conditions. A major dispersal event follows the death of a reproductive. Differences in colony cohesion, ethology and the hormonal profiles of non-reproductive animals suggests that eusociality evolved along different pathways in these two phylogenetically divergent genera of the Bathyergidae.     

Floodplain management: Land acquisition versus preservation of historic buildings in Cambridge,Ontario, Canada

Non-structural adjustments in floodplain management are often avoided because they are seen to infringe on personal rights, adversely affect property values and restrict local tax bases. Land acquisition programs in urban areas encounter a further problem when they lead to demolition of buildings and other structures considered to have historical or architectural value. An experience in Cambridge, Ontario demonstrates that the potential conflict between flood damage reduction and historical preservation objectives can be exacerbated as a result of uncoordinated planning efforts, inflexibility in interpreting mandates, unclear roles for participating agencies, and lack of cooperation Many of these dilemmas can be resolved through consultation and discussion early in the planning process as well as through a willingness to be flexible and to search for a compromise     

Assimilation of symbiont-derived photosynthates in some solitary and colonial radiolaria

Evidence for host assimilation of ¹⁴C-labeled symbiont photosynthates is presented from laboratory studies of the solitary radiolarian Thalassicolla nucleata and the colonial species Collosphaera huxleyi. The amount of ¹⁴C-labeled product assimilated in the central capsule of T. nucleata is directly related to the amount of ¹⁴C incorporated by the symbionts. In C. huxleyi central capsules, the percentage of ¹⁴C-label occurring in the water-soluble fraction is 38% and in the lipid-soluble fraction is 20%, the remainder being in insoluble products. Within the lipid-soluble fraction, a substantial percentage of the ¹⁴C activity is associated with the triglyceride and wax ester fractions. The significance of these findings is discussed in relation to the possible physiological role of symbionts in sustaining the host and stabilizing the host-symbiont association.     

Triclosan in waste and surface waters from the upper Detroit River by liquid chromatography-electrospray-tandem quadrupole mass spectrometry

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is an antimicroibial disinfectant agent used in a wide array of consumer products. An analytical method based on solid-phase extraction (SPE) followed by reverse phase, liquid chromatography coupled with electrospray ionization (negative)-tandem quadrupole mass spectrometry (LC-ESI(-)-MS/MS; in the multiple reaction monitoring (MRM) mode) was developed, optimized and validated for the determination of triclosan in wastewater/sewage treatment plant (WSTP) effluent and surface waters from the upper Detroit River (Canada). The mean recoveries (+/-%RSD) of triclosan and the internal standard 2'-HO-tribromodiphenyl ether (2'-HO-BDE-28) spiked to surface water and WSTP effluent samples ranged similarly from 104+/-8% and 91+/-10%, respectively, and method limits of quantification were in the low ppb/high ppt range. However, ESI(-) enhancement was found for both analytes due to sample matrix effects, as indicated by % process efficiencies (a measure of ESI(-) enhancement/suppression), which were in the 111-128% range. We report the first known assessment of triclosan in the Detroit River watershed of the Great Lakes, which preliminarily examined the presence and UV-treatment effects on triclosan in effluent from the major WSTP serving the City of Windsor, Ontario, Canada, and fate in surface waters of the upper Detroit River. Triclosan in WSTP effluent decreased 22% after final UV treatment to a mean concentration of 63 ng/L. Concentrations were further reduced to 4 and 8 ng/L (a >90% reduction) in surface water samples from sites downstream on the Canadian shoreline of the Detroit River, which was due to dilution. Two hydroxylated tribrominated diphenyl ethers, which are structurally similar to triclosan, were also detected in WSTP effluent and surface water samples.