Climate change, keystone predation, and biodiversity loss

Climate change can affect organisms both directly via physiological stress and indirectly via changing relationships among species. However, we do not fully understand how changing interspecific relationships contribute to community- and ecosystem-level responses to environmental forcing. I used experiments and spatial and temporal comparisons to demonstrate that warming substantially reduces predator-free space on rocky shores. The vertical extent of mussel beds decreased by 51% in 52 years, and reproductive populations of mussels disappeared at several sites. Prey species were able to occupy a hot, extralimital site if predation pressure was experimentally reduced, and local species richness more than doubled as a result. These results suggest that anthropogenic climate change can alter interspecific interactions and produce unexpected changes in species distributions, community structure, and diversity.     

Effect of low light and high noise on behavioural activity, physiological indicators of stress and production in laying hens

1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production.

2. The study was designed to investigate whether chronic exposure to continuous noise (60?dB(A) vs. 80?dB(A)) and/or light intensity (150?lux vs. 5?lux) during the critical period of coming into lay (16–24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens.

3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150?lux; hens in the high noise pens rested more frequently than those in quieter pens.

4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise.

5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.     

Evaluation of the zoonotic potential of Giardia duodenalis in fecal samples from dogs and cats in Ontario

This study determined the distribution and zoonotic potential of Giardia duodenalis assemblage types among canine and feline fecal samples from Ontario. The effectiveness of Giardia assemblage typing methods by sequencing the genes of small subunit ribosomal RNA (ssu-rRNA), β-giardin (bg), glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) was evaluated simultaneously. From 2008 to 2010, 118 canine and 15 feline Giardia positive fecal samples were tested. The ssu-rRNA sequencing method typed 64% (75/118) and 87% (13/15) of the Giardia-positive canine and feline samples, respectively. Among the typeable samples, 68% (51/75) of canine samples contained G. duodenalis assemblage D and 31% (23/75) contained G. duodenalis assemblage C (both non-zoonotic assemblage types). Only 1% (1/75) of the typeable canine samples contained a potentially zoonotic assemblage B. In contrast, 100% (13/13) of the typeable feline samples contained potentially zoonotic assemblages A (n = 12) or B (n = 1).     

The dynamics of groundwater table and salinity over 17 years in Khorezm

Salinization of irrigated agricultural land threatens ecological sustainability and livelihoods of people. Salinization is especially severe in the dry lowlands world-wide and in Central Asia where large amounts of salts accumulated in the soil profile, originating from shallow saline groundwater (GW). Analysis of the unique dataset of 2000 monitoring wells of GW table and salinity in lowland Khorezm region of Uzbekistan over the period of 1990 till 2006 showed shallow GW levels of 1.1-1.4 m (±0.48-0.66 m) at start of leaching periods and 0.9-1.4 (±0.43-0.63 m) in July during the annual growing seasons. While leaching efficiency is decreased, shallow GW in July is far above the optimum levels of 1.4-1.5 m. The effects of topography, soil texture, and irrigation and drainage networks were found to favor shallow GW forced by excessive water diversion. The drainage network, which is seen by many specialists as underdeveloped and its improvement necessary to arrest unacceptable GW levels, is being used under its full capacity. The solution to alleviate land degradation is not only an improved drainage, but better controlled and more flexible water management.