An estimate of predation rate and relative preference for algal versus crustacean prey by a spongiose skeletal radiolarian

Solitary radiolarians (Spongodrymus sp.) in laboratory cultures consumed ¹⁴C-labeled Amphidinium carteri and Coccolithus huxleyi more than Isochrysis galbana or Thalassiosira fluviatilis. The ratio of A. carteri protein consumed per unit time to the amount of Artemia sp. nauplius protein consumed (P/Z) was 6.7×10^-2 indicating that these omnivorous radiolarians tend to consume more zooplankton protein than phytoplankton protein.     

Foliar injury air pollution surveys of eastern white pine (Pinus strobus L.): A review

A thorough review and critical evaluation of field surveys from 1900 to the present of foliar injury to Pinus strobus L. supposedly caused by air pollution was undertaken. Ninety percent of the surveys failed to meet current scientific standards of acceptability. The conduct and peer review of surveys has been poor and the correct injury symptoms have not always been used. Data were obtained for nine that met screening criteria and injury incidence and severity were mapped. Three fourths of the counties in the natural and planted range of eastern white pine have not been scientifically surveyed, so generalizations regarding large-scale spatial patterns of eastern white pine foliar pathological conditions were not possible. However, recent growth and inventory data indicate that growth throughout the natural range regardless of air pollution or other stresses (e.g. blister rust) is excellent, suggesting that regional performance and foliar conditions are unrelated. Sufficient compelling corroborative evidence was found to conclude that a general decline of eastern white pine throughout its range is not a tenable finding.The putative air pollution sensitivity of eastern white pine appears to be based on studies published between 1963 and 1973 on hypersensitive individuals that are no longer being observed in the field. More recent research on eastern white pine has noted a lack of sensitivity and/or high variability of response. The idea that eastern white pine as a species is highly sensitive to air pollution is no longer supported by the available evidence. However, hypersensitive juvenile individuals comprising no more than 8–9% of the total population may still germinate and grow for a brief period of time (because old enough parent trees are still alive) but soon succumb to current levels of ozone and sulfur dioxide in the environment or are suppressed by tolerant neighbors. This phenomenon has been documented anecdotally and is more aptly called tree decline instead of forest decline. An emerging working hypothesis to explain recent reports of unusual eastern white pine tolerance is that sufficient time has elapsed for tree decline to have occurred leading to a gradual elimination of sensitive genotypes from populations.     

Polybrominated diphenyl ethers in two species of marine top predators from England and Wales

During an earlier study, polybrominated diphenyl ethers were detected at high concentrations in fish and sediments downstream of a manufacturing site in NE England. We have now undertaken analysis of 14 tri- to heptabromodiphenyl ether congeners in tissues of two species of marine top predators exposed to these compounds through their consumption of fish. In this paper we report data for 47 cormorants and 60 harbour porpoises from England and Wales, sampled during the period 1996-2000. Concentrations of the summed congeners ranged from 1.8 to 140 microg kg(-1) wet weight in cormorant livers, and from not detected to 6900 microg kg(-1) wet weight in porpoise blubber. The major congeners present were generally BDE47, BDE99 and BDE100. There was little correlation between concentrations of chlorobiphenyls (as the sum of 25 individual congeners) and the sum of the 14 BDE congeners determined, particularly for the porpoises.     

Floristic summary of plant species in the air pollution literature

A floristic summary and analysis was performed on a list of the plant species that have been studied for the effects of gaseous and chemical air pollutants on vegetation in order to compare the species with the flora of North America north of Mexico. The scientific names of 2081 vascular plant species were extracted from almost 4000 journal articles stored in two large literature databases on the effects of air pollutants on plants. Three quarters of the plant species studied occur in North America, but this was only 7% of the total North American flora. Sixteen percent and 56% of all North American genera and families have been studied. The most studied genus is Pinus with 70% of the North American species studied, and the most studied family is the grass family, with 12% of the species studied. Although Pinus is ranked 86th in the North American flora, the grass family is ranked third, indicating that representation at the family level is better than at the genus level. All of the top ten families in North America are represented in the top 20 families in the air pollution effects literature, but only one genus (Lupinus) in the top ten genera in North America is represented in the top thirteen genera in the air pollution literature.     

Consequences of dominance: a review of evenness effects on local and regional ecosystem processes

The composition of communities is strongly altered by anthropogenic manipulations of biogeochemical cycles, abiotic conditions, and trophic structure in all major ecosystems. Whereas the effects of species loss on ecosystem processes have received broad attention, the consequences of altered species dominance for emergent properties of communities and ecosystems are poorly investigated. Here we propose a framework guiding our understanding of how dominance affects species interactions within communities, processes within ecosystems, and dynamics on regional scales. Dominance (or the complementary term, evenness) reflects the distribution of traits in a community, which in turn affects the strength and sign of both intraspecifc and interspecific interactions. Consequently, dominance also mediates the effect of such interactions on species coexistence. We review the evidence for the fact that dominance directly affects ecosystem functions such as process rates via species identity (the dominant trait) and evenness (the frequency distribution of traits), and indirectly alters the relationship between process rates and species richness. Dominance also influences the temporal and spatial variability of aggregate community properties and compositional stability (invasibility). Finally, we propose that dominance affects regional species coexistence by altering metacommunity dynamics. Local dominance leads to high beta diversity, and rare species can persist because of source-sink dynamics, but anthropogenically induced environmental changes result in regional dominance and low beta diversity, reducing regional coexistence. Given the rapid anthropogenic alterations of dominance in many ecosystems and the strong implications of these changes, dominance should be considered explicitly in the analysis of consequences of altered biodiversity.     

Birds in agricultural mosaics: the influence of landscape pattern and countryside heterogeneity.

Agricultural environments are critical to the conservation of biota throughout the world. Efforts to identify key influences on the conservation status of fauna in such environments have taken complementary approaches. Many studies have focused on the role of remnant or seminatural vegetation and emphasized the influence on biota of spatial patterns in the landscape. Others have recognized that many species use diverse "countryside" elements within farmland, and emphasize the benefits of landscape heterogeneity for conservation. Here, we investigated the effect of independent measures of both the spatial pattern (extent and configuration) and heterogeneity of elements (i.e., land uses/vegetation types) on bird occurrence in farm-scale agricultural mosaics in southeastern Australia. Birds were sampled in all types of elements in 27 mosaics (each 1 x 1 km) selected to incorporate variation in cover of native vegetation and the number of different element types in the mosaic. We used an information-theoretic approach to identify the mosaic properties that most strongly influenced bird species richness. Subgroups of birds based on habitat requirements responded most strongly to the extent of preferred elements in mosaics. Woodland birds were richer in mosaics with higher cover of native vegetation while open-tolerant species responded to the extent of scattered trees. In contrast, for total species richness, mosaic heterogeneity (richness of element types) and landscape context (cover of native vegetation in surrounding area) had the greatest influence. These results showed that up to 76% of landscape-level variation in richness of bird groups is attributable to mosaic properties directly amenable to management by landowners. Key implications include (1) conservation goals for farm landscapes must be carefully defined because the richness of different faunal components is influenced by different mosaic properties; (2) the extent of native vegetation is a critical influence in agricultural environments because it drives the farm-scale richness of woodland birds and has a broader context effect on total bird richness in mosaics; (3) land-use practices that enhance the heterogeneity of farmland mosaics are beneficial for native birds; and (4) the cumulative effect of even small elements in farm mosaics contribute to the structural properties of entire landscapes.     

A legal assessment of private land conservation in South America

Privately protected areas (PPAs) are a potentially innovative conservation tool. Legal recognition is necessary for their success, especially where there are institutional challenges to nature conservation, such as in South America. Although PPAs have increased in South America since the early 2000s, there is a critical information gap pertaining to their legal frameworks. We analyzed the level of landowner commitment to and governmental support for PPAs across countries in South America that officially recognize PPAs. We analyzed the legal framework governing PPAs and reviewed literature on them. This process was done in English and Spanish. The information we gathered was validated by 16 conservation experts from 10 South American countries. Because Peru is 1 of only 2 South American countries where local communities create and manage PPAs, we studied Peruvian PPAs in more detail by examining official creation documents and interviewing 13 local conservation professionals. We found inadequate minimum duration of PPAs and vague guidelines for conducting economic activities within them and a lack of governmental support (e.g., financial and technical support) for PPAs. Support was limited to the exemption from rural property taxes, which are relatively low compared with countries outside South America. In Peru, PPAs run by individuals and communities needed different legal frameworks because they were created with different objectives and had different sizes and duration of commitments. The prompt improvement of legal frameworks across South America is necessary for PPAs to achieve their aim of being places for enduring nature conservation in the region.     

Indoor acrolein emission and decay rates resulting from domestic cooking events

Acrolein (2-propenal) is a common constituent of both indoor and outdoor air, can exacerbate asthma in children, and may contribute to other chronic lung diseases. Recent studies have found high indoor levels of acrolein and other carbonyls compared to outdoor ambient concentrations. Heated cooking oils produce considerable amounts of acrolein, thus cooking is likely an important source of indoor acrolein. A series of cooking experiments were conducted to determine the emission rates of acrolein and other volatile carbonyls for different types of cooking oils (canola, soybean, corn and olive oils) and deep-frying different food items. Similar concentrations and emission rates of carbonyls were found when different vegetable oils were used to deep-fry the same food product. The food item being deep-fried was generally not a significant source of carbonyls compared to the cooking oil. The oil cooking events resulted in high concentrations of acrolein that were in the range of 26.4–64.5 μg m^?3. These concentrations exceed all the chronic regulatory exposure limits and many of the acute exposure limits. The air exchange rate and the decay rate of the carbonyls were monitored to estimate the half-life of the carbonyls. The half-life for acrolein was 14.4 ± 2.6 h, which indicates that indoor acrolein concentrations can persist for considerable time after cooking in poorly-ventilated homes.     

Bottomfast Ice Mapping and the Measurement of Ice Thickness on Tundra Lakes Using C‐Band Synthetic Aperture Radar Remote Sensing1

Abstract: Industrial activity in Canada’s north is increasing, placing demands on the use of water from lakes to build ice roads. Winter water withdrawal from these lakes has the potential to impact overwintering fish. Removal of water from small lakes can decrease oxygen and habitat available to fish. To address this issue, a protocol has been developed by the Department of Fisheries and Oceans outlining water withdrawal thresholds. Bathymetric surveys are the traditional method to determine lake depth, but are costly given the remoteness of northern lakes. This paper investigates the use of satellite C‐band synthetic aperture radar (SAR) remote sensing technology as a potential alternative or complement to traditional survey methods. Previous research has shown that a SAR can detect the transition from grounded to floating ice on lakes, or if a lake is completely frozen. Grounded ice has a dark signature while floating ice appears very bright in contrast. Similar results were observed for the datasets acquired in the study area. This suggests that lakes that freeze completely to the bottom can be identified using SAR. Such water bodies would not be viable fish overwintering habitat and can therefore be used as water sources without thresholds necessary. However, attempts to accurately calculate the depth of the ice at the grounded‐floating ice boundary using bathymetric profiles acquired in the summer and lake ice thickness measurements from a reference lake near Inuvik proved to be unreliable.