The difference conservation makes to extinction risk of the world's ungulates

Previous studies show that conservation actions have prevented extinctions, recovered populations, and reduced declining trends in global biodiversity. However, all studies to date have substantially underestimated the difference conservation action makes because they failed to account fully for what would have happened in the absence thereof. We undertook a scenario‐based thought experiment to better quantify the effect conservation actions have had on the extinction risk of the world's 235 recognized ungulate species. We did so by comparing species’ observed conservation status in 2008 with their estimated status under counterfactual scenarios in which conservation efforts ceased in 1996. We estimated that without conservation at least 148 species would have deteriorated by one International Union for Conservation of Nature (IUCN) Red List category, including 6 species that now would be listed as extinct or extinct in the wild. The overall decline in the conservation status of ungulates would have been nearly 8 times worse than observed. This trend would have been greater still if not for conservation on private lands. While some species have benefited from highly targeted interventions, such as reintroduction, most benefited collaterally from conservation such as habitat protection. We found that the difference conservation action makes to the conservation status of the world's ungulate species is likely to be higher than previously estimated. Increased, and sustained, investment could help achieve further improvements.     

Relationships between regulated DBPs and emerging DBPs of health concern in U.S. drinking water

A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewater-impacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs (HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs (haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate (a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies (primarily for iodinated THMs), but seldom in full-scale studies (where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI; however, ∼50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.     

Structure of pathways in ecological networks: relationships between length and number

In ecosystems network, structure determines adjacent (direct) and non-adjacent (indirect) pathways over which energy, matter, and information can flow. The more pathways, the more possible ways the conservative substance can move in zero-sum transactions between network nodes that the pathways interconnect, and the more possible non-conservative, nonzero-sum relations can be secondarily derived from these. Structural analysis is a tool we employ, from a family of input–output methods for exploring zero- and nonzero-sum attributes of environmental networks, to count pathways of varying length between network nodes. In this paper, we examine the relationship between pathway length (k) and number (P_k) as determined by system size (n, number of nodes) and extent and pattern of connectance (C). We develop a measure (m_a) of pathway growth in numbers with increasing length, and then normalize this to the maximum rate possible (m_a/m_c) for a given system size. These measures apply to two pathway types—paths, m_a(0) and m_a(0)/m_c(0), which forbid adjacent node repetitions, and walks, m_a(1) and m_a(1)/m_c(1), which allow them. We find that network size has a curvilinear effect on the pathway number versus length relationship, and extent and pattern of connectance are convolved. Values computed for the paths and walks of three ecosystem models (oyster reef, freshwater marsh, and reservoir cove) are used to compare their pathway structure.     

Introduction History and Invasion Patterns of Ammophila arenaria on the North Coast of California

European beachgrass ( Ammophila arenaria [L] Link), introduced to stabilize sand, is fully naturalized in central and northern California and has supplanted populations of native dune plants in many areas, including the North Spit of Humboldt Bay. We interpreted air photos of the North Spit for the presence of Ammophila arenaria at three points in time: 1939/1942, 1962, and 1989. To quantify the spread and to detect invasion patterns of Ammophila , we then compiled maps using a geographic information system. We documented introduction dates and locations to improve the accuracy of our photo interpretation. Interpretation of the three photo series revealed invasion and expansion of Ammophila in both foredunes and inland dunes. The most dramatic increase in cover was found in the foredunes, whereas documented and presumed plantings were found mostly on inland dunes. Adjusting for intentional eradication, Ammophila cover on the North Spit was found to have increased between 1939 and 1989 by 574%. The square root of the area occupied by Ammophila on the North Spit increased linearly with time, conforming to biological invasion theory.     

The selective advantages of cannibalism in a Neotropical mosquito

We investigated the benefits of larval cannibalism in the Neotropical mosquito Trichoprosopon digitatum. The clutch size of the mosquito in the field was strongly correlated with adult female size, indicating a fitness advantage to being large. In controlled laboratory experiments, we compared the survivorship and eventual adult sizes of larvae that were given the opportunity to cannibalise conspecifics throughout their lifetimes with the survivorship and adult sizes of larvae that were prevented from cannibalising. Since the benefits of cannibalism are likely to depend on the context in which it occurs, the experiment was conducted at two levels of alternative food availability. When food availability was high most larvae survived to adulthood, females cannibalised more than males and there was no measurable advantage to cannibalism in terms of survival rate, emergence time or adult size. Larvae were significantly more cannibalistic when food availability was lower, although under these conditions no larvae survived to adulthood. Nevertheless, under low food an important fitness benefit to cannibalism was revealed: individuals which had the opportunity to cannibalise survived significantly longer as larvae than those which did not. This increased longevity is likely to provide an important advantage to mosquito larvae when they wait for the input of unpredictable food sources. Received: 7 October 1995/Accepted after revision: 13 April 1996     

Contrasting structure and composition of the understory in species-rich tropical rain forests

In large samples of trees > or = 1 cm dbh (more than 1 million trees and 3000 species), in six lowland tropical forests on three continents, we assigned species with >30 individuals to one of six classes of stature at maturity (SAM). We then compared the proportional representation of understory trees (1-2 cm dbh) among these classes. The understory of the three Asian sites was predominantly composed of the saplings of large-canopy trees whereas the African and American sites were more richly stocked with trees of the smaller SAM classes. Differences in class representation were related to taxonomic families that were present exclusively in one continent or another. Families found in the Asian plots but not in the American plot (e.g., Dipterocarpaceae, Fagaceae) were predominantly species of the largest SAM classes, whereas families exclusive to the American plots (e.g., Melastomataceae sensu stricto, Piperaceae, and Malvaceae [Bombacacoidea]) were predominantly species of small classes. The African plot was similar to Asia in the absence of those American families rich in understory species, while similar to America in lacking the Asian families rich in canopy species. The numerous understory species of Africa were chiefly derived from families shared with Asia and/or America. The ratio of saplings (1-2 cm dbh) to conspecific canopy trees (>40 cm dbh) was lower in American plots than in the Asian plots. Possible explanations for these differences include phenology, moisture and soil fertility regimes, phyletic constraints, and the role of early successional plants in forest development. These results demonstrate that tropical forests that appear similar in tree number, basal area, and the family taxonomy of canopy trees nonetheless differ in ecological structure in ways that may impact the ecology of pollinators, dispersers, and herbivores and might reflect fundamental differences in canopy tree regeneration.     

The challenge of providing environmental flow rules to sustain river ecosystems.

Accounting for natural differences in flow variability among rivers, and understanding the importance of this for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide, is a great challenge for water managers and scientists. Nevertheless, despite considerable progress in understanding how flow variability sustains river ecosystems, there is a growing temptation to ignore natural system complexity in favor of simplistic, static, environmental flow "rules" to resolve pressing river management issues. We argue that such approaches are misguided and will ultimately contribute to further degradation of river ecosystems. In the absence of detailed empirical information of environmental flow requirements for rivers, we propose a generic approach that incorporates essential aspects of natural flow variability shared across particular classes of rivers that can be validated with empirical biological data and other information in a calibration process. We argue that this approach can bridge the gap between simple hydrological "rules of thumb" and more comprehensive environmental flow assessments and experimental flow restoration projects.     

Records of atmospheric delivery of pyrolysis-derived pollutants in recent mountain lake sediments of the Julian Alps (NW Slovenia)

The historical record of the input of pyrolysis-derived pollutants via the atmosphere, i.e. black carbon (BC), polycyclic aromatic hydrocarbons (PAH) and spheroidal carbonaceous particles (SCP) was measured in the sediments of three remote alpine lakes situated in the Julian Alps, northwest Slovenia. Parallel sedimentary trends for BC, PAH and SCP were observed across the Julian Alps and relationships among these contaminants are discussed. Inputs of these pyrolytic-contaminants to sediments of remote lakes started to rise at the end of the 19th century, while their peak inputs were observed in the mid-20th century, amounting up to 6.0 gm(-2) yr(-1) for BC, 5200 x 10(4) m(-2) yr(-1) for SCP and 2900 microg m(-2) yr(-1) for PAH. In the last two to three decades, inputs decreased substantially, by a factor of up to 3 for BC, 7 for SCP and at least 3 for PAH.