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Network analysis offers insight into the structure and function of ecological communities, but little is known about how empirical networks change over time during perturbations. \"Nest webs\" are commensal networks that link secondary cavity-nesting vertebrates (e.g., bluebirds, ducks, and squirrels, which depend on tree cavities for nesting) with the excavators (e.g., woodpeckers) that produce cavities. In central British Columbia, Canada, Northern Flicker ( Colaptes auratus ) is considered a keystone excavator, providing most cavities for secondary cavity-nesters. However, roles of species in the network, and overall network architecture, are expected to vary with population fluctuations. Many excavator species increased in abundance in association with a pulse of food (adult and larval beetles) during an outbreak of mountain pine beetle ( Dendroctonus ponderosae ), which peaked in 2003-2004. We studied nest-web dynamics from 1998 to 2011 to determine how network architecture changed during this resource pulse. Cavity availability increased at the onset of the beetle outbreak and peaked in 2005. During and after the outbreak, secondary cavity-nesters increased their use of cavities made by five species of beetle-eating excavators, and decreased their use of flicker cavities. We found low link turnover, with 74% of links conserved from year to year. Nevertheless, the network increased in evenness and diversity of interactions, and declined slightly in nestedness and niche overlap. These patterns remained evident seven years after the beetle outbreak, suggesting a legacy effect. In contrast to previous snapshot studies of nest webs, our dynamic approach reveals how the role of each cavity producer, and thus quantitative network architecture, can vary over time. The increase in interaction diversity with the beetle outbreak adds to growing evidence that insect outbreaks can increase components of biodiversity in forest ecosystems at various temporal scales. The observed changes in (quantitative) network architecture contrast with the relatively stable (qualitative) architecture of empirical mutualistic networks that have been studied to date. However, they are consistent with recent theory on the importance of population fluctuations in driving network architecture. Our results support the view that models should allow for the possibility of rewiring (species switching partners) to avoid overestimation of secondary extinction risk.

An unsettling study of two tragic events at an Indian residential school in British Columbia which serve as a microcosm of the profound impact the residential school system had on Aboriginal communities in Canada throughout this century. The book's focal points are the death of a runaway boy and the suicide of another while they were students at the Williams Lake Indian Residential School during the early part of this century. Embedded in these stories is the complex relationship between the Department of Indian Affairs, the Oblates, and the Aboriginal communities that in turn has influenced relations between government, church, and Aboriginals today.

Freshwater lakes are an important component of the global carbon cycle through both organic carbon (OC) sequestration and carbon dioxide (CO2) emission. Most lakes have a net annual loss of CO2 to the atmosphere and substantial current evidence suggests thatbiologic mineralization of allochthonous OC maintains this flux. Because net CO2 flux to the atmosphere implies net mineralization of OC within the lake ecosystem, it is also commonly assumed that net annual CO2 emission indicates negative net ecosystem production (NEP). We explored the relationship between atmospheric CO2 emission and NEP in two lakes known to have contrasting hydrologic characteristics and net CO2 emission. We calculated NEP for calendar year 2004 using whole‐lake OC and inorganic carbon (IC) budgets, NEPOC and NEPIC, respectively, and compared the resulting values to measured annual CO2 flux from the lakes. In both lakes, NEPOC and NEPIC were positive, indicating net autotrophy. Therefore CO2 emission from these lakes was apparently not supported by mineralization of allochthonous organic material. In both lakes, hydrologic CO2 inputs, as well as CO2 evolved from net calcite precipitation, could account for the net CO2 emission. NEP calculated from diel CO2 measurements was also affected by hydrologic inputs of CO2. These results indicate that CO2 emission and positive NEP may coincide in lakes, especially in carbonate terrain, and that all potential geologic, biogeochemical, and hydrologic sources of CO2 need to be accounted for when using CO2 concentrations to infer lake NEP.

Tree cavities are a vital multi-annual resource used by cavity-nesting birds and mammals for nesting and shelter. The abundance of this resource will be influenced by the rates at which cavities are created and destroyed. We applied the demographic concepts of survival and longevity to populations of tree holes to investigate rates of loss for cavities in three tree species, as well as how characteristics of nest trees, habitat type, and species of excavator affected the persistence of tree cavities in trembling aspen, Populus tremuloides (95% of cavities were in aspen trees), in interior British Columbia, Canada. By modeling survival of 1635 nesting cavities in aspen over a time span of 16 years, we found that the decay stage of the nest tree was the most important factor determining cavity longevity. Cavities in trees with advanced decay had a relatively short median longevity of 7 years (95% CI 6-9 years), whereas those in living trees had a median longevity of more than 15 years. We found that cavity longevity was greater in continuous forest than in aspen grove habitat. Interestingly, cavities formed by weak excavators survived as long as those created by Northern Flickers ( Colaptes auratus ), despite occurring in more decayed tree stems. Thus, weak excavators may be selecting for characteristics that make a tree persistent, such as a broken top. Our results indicate that retention of cavities in large, live aspen trees is necessary to conserve persistent cavities, and that cavity longevity will have a large effect on the structure and function of cavity-using vertebrate communities.

Freshwater reservoirs are an important source of the greenhouse gas methane (CH₄) to the atmosphere, but global emission estimates are poorly constrained (13.3–52.5 Tg C yr−1), partially due to extreme spatial variability in emission rates within and among reservoirs. Spatial heterogeneity in the availability of organic matter (OM) for biological CH₄ production by methanogenic archaea may be an important contributor to this variation. To investigate this, we measured sediment CH₄ potential production rates, OM source and quantity, and methanogen community composition at 15 sites within a eutrophic reservoir in Ohio, USA. CH₄ production rates were highest in the shallow riverine inlet zone of the reservoir, even when rates were normalized to OM quantity, indicating that OM was more readily utilized by methanogens in the riverine zone than in the transitional or lacustrine zones. Sediment stable isotopes and C:N indicated a greater proportion of terrestrial OM in the particulate sediment of this zone. Methanogens were present at all sites, but the riverine zone contained a higher relative abundance of methanogens capable of acetoclastic and methylotrophic methanogenesis, likely reflecting differences in decomposition processes or OM quality. While we found that methane potential production rates were negatively correlated with autochthonous carbon in particulate sediment OM, rates were positively correlated with indicators of autochthonous carbon in the porewater dissolved OM. It is likely that both dissolved and particulate sediment OM affect CH₄ production rates, and that both terrestrial and aquatic OM sources are important in the riverine methane production hot spot.

Surface water and ground water watersheds commonly do not coincide. This condition is particularly relevant to understanding biogeochemical processes in small watersheds, where detailed accounting of water and solute fluxes commonly are done. Ground water watersheds are not as easily defined as surface watersheds because (1) they are not observable from land surface; (2) ground water flow systems of different magnitude can be superimposed on one another; and (3) ground water divides may move in response to dynamic recharge and discharge conditions. Field studies of relatively permeable terrain in Wisconsin, Minnesota, and Nebraska indicate that lakes and wetlands in small watersheds located near the lower end of extensive ground water flow systems receive ground water inflow from shallow flow systems that extend far beyond their surface watershed, and they may also receive ground water inflow from deeper regional flow systems that pass at depth beneath local flow systems. Field studies of mountainous terrain that have low‐permeability deposits in New Hampshire and Costa Rica also indicate that surface water bodies receive ground water inflow from sources beyond their local surface watersheds. Field studies of lakes and wetlands in North Dakota, Nebraska, and Germany indicate that ground water divides move in response to changing climate conditions, resulting in a variable source of ground water inflow to those surface water bodies.

The bizarre morphology of living Pycnogonida, known colloquially as sea spiders, has long fueled dissent over their status within the arthropods. Pycnogonids figure prominently in recent analyses of anterior limb homologies and ancestral crown-group euarthropod relationships, with support for the concept of Pycnogonida as sister taxon to Euchelicerata now contested by proponents of a more basal position between Radiodonta and all other arthropods. A challenge to further elucidation of their phylogenetic position is the exceptional rarity and disjunct distribution of pycnogonids in the fossil record, due largely to their fragile unmineralized exoskeletons. New fossil discoveries therefore have the potential to add significantly to knowledge of their evolution, paleoecology, and paleobiogeography. Here we report the first known occurrence of fossil pycnogonids from rocks of Ordovician age, bridging a 65 Myr gap between controversial late Cambrian larval forms and a single documented Silurian specimen. The new taxon, Palaeomarachne granulata n. gen. n. sp., from the Upper Ordovician (ca. 450 Ma) William Lake Konservat-Lagerstätte deposit in Manitoba, Canada, is also the first reported from Laurentia. It is the only record thus far of a fossil sea spider in rocks of demonstrably shallow marine origin. Four incomplete, partially disarticulated molts represent a relatively large, robust animal with a series of five segment-like elements in a ‘head' region that does not incorporate the first of four preserved limb-bearing trunk segments. This unique pattern may reflect the plesiomorphic condition prior to complete fusion of anterior ‘head' elements and first trunk segment to form a cephalosoma, as seen in all eupycnogonids. Palaeomarachne granulata is interpreted as occupying a basal stem-group position in the Pycnogonida.

The concentrations of organic carbon (OC) and CaCO3 in lake sediments are often inversely related. This relation occurs in surface sediments from different locations in the same lake, surface sediments from different lakes, and with depth in Holocene sediments. Where data on accumulation rates are available, the relation holds for organic carbon and CaCO3 accumulation rates as well. An increase of several percent OC is accompanied by a decrease of several tens of percent CaCO3 indicating that the inverse relation is not due to simple dilution of one component by another. It appears from core data that once the OC concentration in the sediments becomes greater than about 12%, the CO2 produced by decomposition of that OC and production of organic acids lowers the pH of anoxic pore waters enough to dissolve any CaCO3 that reaches the sediment-water interface. In a lake with a seasonally anoxic hypolimnion, processes in the water column also can produce an inverse relation between OC and CaCO3 over time. If productivity of the lake increases, the rain rate of OC from the epilimnion increases. Biogenic removal of CO2 and accompanying increase in pH also may increase the production of CaCO3. However, the decomposition of organic matter in the hypolimnion will decrease the pH of the hypolimnion causing greater dissolution of CaCO3 and therefore a decrease in the rain rate of CaCO3 to the sediment-water interface.[PUBLICATION ABSTRACT]

Williams and Shingobee lakes are at opposite ends of the local ground water flow system in the Shingobee River Headwaters Area (SRHA) in north‐central Minnesota. Williams Lake, situated near the highest point in the flow system, has no surface inlet or outlet, and ground water and precipitation are the only sources of water. Shingobee Lake, situated at the lowest point in the flow system, has the Shingobee River as an inlet and outlet. Ground water directly contributes an estimated one‐fourth of the water input to Shingobee Lake. The Shingobee River also receives large amounts of ground water discharge along its reach to Shingobee Lake providing a large, indirect source of ground water to the lake. Differences in nutrient concentrations reflect the residence times and nutrient supplies of these two lakes. The average phosphorus content of Shingobee Lake is about twice that of Williams Lake. Consequently, phy‐toplankton productivity in Shingobee Lake is much higher than in Williams Lake, leading to an oxygen‐deficient (<1 ppm dissolved oxygen) hypolimnion within a month after overturn in both the spring and fall. Because of the extreme reducing conditions in the hypolimnion of Shingobee Lake, high concentrations of dissolved iron and manganese are present there during summer stratification. In some years, the manganese concentration in the hypolimnion of Shingobee Lake remains high throughout the year. Precipitation of iron and manganese minerals, presumed to be X‐ray amorphous oxyhydroxides, at periods of fall and spring overturn result in concentrations of iron and manganese in surface sediments of Shingobee Lake that are seven times and 27 times higher, respectively, than can be explained by contributions of iron and manganese from detrital aluminosilicates. These findings indicate that the source and amounts of this excess iron and manganese found in the sediments are correlated to the amount of iron‐ and manganese‐rich ground water discharging to Shingobee Lake. Because iron and manganese oxyhydroxides are efficient adsorbers of phosphorus, concentrations of phosphorus are also high in the sediments of Shingobee Lake. Without this sequestration of phosphorus, the productivity of Shingobee Lake would probably be much higher.

It wont be in [Williams Lake, Thompson], because it is considered urban, but in the rural and remote areas we are implementing community paramedic programs, Thompson said. This will involve PCP IV training for paramedics in smaller communities such as Alexis Creek and Anahim Lake. Cariboo-Fraser district manager Blaine Wiggins rents an office at the Soda Creek Health Centre, and oversees eight stations serving approximately 40 First Nations and non-First Nations communities in the region. Even renting the office in Soda Creek has enabled Wiggins to be part of the districts First Nations rural health community and tap into being in partnership with the health clinic there.