Bayesian Networks and Adaptive Management of Wildlife Habitat

Abstract: Adaptive management is an iterative process of gathering new knowledge regarding a system's behavior and monitoring the ecological consequences of management actions to improve management decisions. Although the concept originated in the 1970s, it is rarely actively incorporated into ecological restoration. Bayesian networks (BNs) are emerging as efficient ecological decision‐support tools well suited to adaptive management, but examples of their application in this capacity are few. We developed a BN within an adaptive‐management framework that focuses on managing the effects of feral grazing and prescribed burning regimes on avian diversity within woodlands of subtropical eastern Australia. We constructed the BN with baseline data to predict bird abundance as a function of habitat structure, grazing pressure, and prescribed burning. Results of sensitivity analyses suggested that grazing pressure increased the abundance of aggressive honeyeaters, which in turn had a strong negative effect on small passerines. Management interventions to reduce pressure of feral grazing and prescribed burning were then conducted, after which we collected a second set of field data to test the response of small passerines to these measures. We used these data, which incorporated ecological changes that may have resulted from the management interventions, to validate and update the BN. The network predictions of small passerine abundance under the new habitat and management conditions were very accurate. The updated BN concluded the first iteration of adaptive management and will be used in planning the next round of management interventions. The unique belief‐updating feature of BNs provides land managers with the flexibility to predict outcomes and evaluate the effectiveness of management interventions.     

Use of an Action‐Selection Framework for Human‐Carnivore Conflict in the Bangladesh Sundarbans

Abstract: Human–carnivore conflict is manifested in the death of humans, livestock, and carnivores. The resulting negative local attitudes and retribution killings imperil the future of many endangered carnivores. We tailored existing management tools to create a framework to facilitate the selection of actions to alleviate human–carnivore conflict and applied the framework to the human–tiger conflict in the Bangladesh Sundarbans. We identified potential actions that consider previous management efforts, local knowledge, cost‐effectiveness, fieldwork experience of authors and project staff, previous research on tiger ecology by the authors, and recommendations from human–carnivore conflict studies in other countries. Our framework includes creation of a profile to improve understanding of the nature of the conflict and its underlying causality. Identified actions include deterrents, education, direct tiger management, and response teams. We ranked actions by their potential to reduce conflict and the monetary cost of their implementation. We ranked tiger‐response teams and monitoring problem tigers as the two best actions because both had relatively high impact and cost‐effectiveness. We believe this framework could be used under a wide range of human–wildlife conflict situations because it provides a structured approach to selection of mitigating actions.     

道南膜技术测定CaCl2溶液体系中汞的化学形态

尝试并探索道南膜技术(DMT)测定溶液体系中Hg化学形态的方法条件.结果表明,0.01mol·1-1CaCl2作为背景溶液时,跨过阳离子交换膜的Hg主要形态并非阳离子而是HgCl2和HgCl3.Hg在阳离子交换膜内扩散为限制Hg跨膜传输的主要因素.Hg在阳离子交换膜内的吸附除静电吸附外还存在结合力更强的化学吸附,成为限制道南膜技术用于Hg形态测定的主要因素.采用动力学DMT方法,缩短试验时间至8h以内,可在一定程度上降低Hg的化学吸附,为DMT方法测定土壤溶液体系中Hg的化学形态提供可能.     

Settlement, recruitment and potential predators and competitors of juvenile echinoderms in the rocky subtidal zone

Recruitment patterns of marine invertebrates are affected both by settlement and early post-settlement events. This study examined the settlement and recruitment patterns of echinoderms at three sites in the rocky subtidal zone of Bocabec Cove, Bay of Fundy, Canada using artificial turf collectors and quadrats on the natural substrate. Potential predators were quantified at two of the sites along transects and in 1-m² quadrats. Both potential predators and competitors were quantified in 0.0625-m² quadrats. Settlement varied across sites (1.5–3 km apart) and two years of sampling (2004, 2005). The site of most potential settlement differed for the three groups of echinoderms: sea urchins (Strongylocentrotus droebachiensis), sea stars (Asterias spp.) and sea cucumber (Psolus fabricii). Settlement densities on the artificial turf collectors tended to be greater than the densities of settlers on the natural substrate. On the natural substrate, the only significant difference between densities of juveniles over time was that newly settled sea stars were found in July and were not found the following October. Large lobsters and carnivorous worms were potential predators with densities that varied between sites. Potential competitors that differed in abundance between sites were herbivorous gastropods and conspecifics for sea urchins; and carnivorous worms for sea stars. This study suggests that patterns of recruitment are either set up by patterns of settlement or by events during the first few weeks/months on the benthic substrate for these echinoderms.     

Turbinaria ornata as an herbivory refuge for associate algae

Habitat associations are an integral part of coral reef community structure. Commonly, one organism lives in such close association within or near another that a spatial refuge occurs, whereby one of the organisms provides protection to the other. This is often the result of defenses of the host deterring an associate organism’s consumers. In Moorea, French Polynesia, the range and abundance of the brown macroalga, Turbinaria ornata, have increased drastically since 1980 such that dense aggregations of this macroalga are a dominant component of the backreef habitat. Turbinaria ornata is both mechanically and chemically defended from herbivores. Other species of macroalgae grow within aggregations of Turbinaria and may benefit from these defenses. This study investigates whether aggregations of Turbinaria create a refuge from herbivory for associate macroalgae. When Turbinaria aggregations were removed experimentally, there was a significant increase in the number of associate algal species. Moreover, an herbivory assay using the palatable local alga Acanthophora spicifera identified herbivory as the mechanism for lower diversity on bommies lacking Turbinaria aggregations. The local increase in algal richness due to the refuge from herbivory afforded by Turbinaria may be an important contribution to macroalgal and community dynamics on reefs in Moorea, French Polynesia.     

Phylogeography of the Antarctic planktotrophic brittle star Ophionotus victoriae reveals genetic structure inconsistent with early life history

In the marine environment, connectivity is influenced by physical oceanography as well as life history and behavioral traits, which in combination with historical events such as geology, physical oceanography, and climate, determine population structure. The Antarctic brittle star Ophionotus victoriae develops via a feeding planktonic larval stage, and therefore has potential for long-distance dispersal throughout its Antarctic/subantarctic range. To evaluate this hypothesis, phylogeography of this ecologically dominant species was elucidated by sequence analysis of two mtDNA genes from individuals collected throughout the Antarctic Peninsula and from two subantarctic islands. Counter to expectations of genetic homogeneity, mtDNA data revealed substantial levels of genetic differentiation as well as diversity. Although there were some genetically homogeneous populations, such as those throughout Bransfield Strait, we found O. victoriae to have significant population structure throughout much of the Antarctic Peninsula, with evidence of potential cryptic speciation between the western and eastern Antarctic Peninsula. Furthermore, Antarctic Peninsula populations were genetically distinct from subantarctic island populations. The low levels of connectivity implied for O. victoriae contrast with those found for many other Antarctic benthic taxa, and suggest a complex interplay between oceanography, recent climate history, and larval ecology.     

Determination of trace metal concentrations in soil profiles of municipal waste dumps in Nigeria

The concentrations of trace metals (Cd, Pb, Cu, Cr, Fe, Ni, Zn and Co) were studied in soil profiles of eight municipal waste dump sites in Warri metropolis. The results indicate that concentrations of trace metals varied widely among the different dumpsites and decreased with depths in a studied soil profile. The accumulation pattern for the heavy metals in the soil profiles follows the order: Fe > Pb > Mn > Co > Cr > Zn > Ni > Cu > Cd. The concentrations of metals found in these sites was below the Canadian remediation criteria for land for agricultural, residential and commercial/industrial purposes except for the cadmium levels in some sites that exceeded criterion values for agricultural and residential. In such sites, remedial actions are required before any form of chosen development can take place. The levels of heavy metals found in these dump sites were higher than that of the control site. The examined metals showed no significant correlation with soil physicochemical properties at the surface horizon, which is suggestive evidence that these metals arise from anthropogenic input.     

Tetrodotoxin affects survival probability of rough-skinned newts (Taricha granulosa) faced with TTX-resistant garter snake predators (Thamnophis sirtalis)

Lethal chemical defenses in prey species can have profound effects on interactions with predators. The presence of lethal defenses in prey can correct the selective imbalance suggested by the life-dinner principle in which the fitness consequences of an encounter between predator and prey should be much greater for the prey species than the predator. Despite the apparent adaptive advantages of lethality the evolution of deadly prey presents a fundamental dilemma. How might lethal defenses confer an individual fitness advantage if both predators and prey die during interactions? We examined the interaction between the rough-skinned newt (Taricha granulosa), which contains a powerful neurotoxin called tetrodotoxin (TTX), and the common garter snake (Thamnophis sirtalis). In some sympatric populations, Th. sirtalis have evolved physiological resistance to TTX. Whether the newts’ toxin confers protection from snake predators or has been disarmed by the snakes’ physiological resistance has not yet been directly tested. In predator–prey trials, newts that were rejected by snakes had greater concentrations of TTX in their skin (4.52 ± 3.49 mg TTX/g skin) than those that were eaten (1.72 ± 1.53 mg TTX/g skin). Despite the plethora of taxa that appear to use TTX defensively, this is the first direct and quantitative demonstration of the antipredator efficacy of TTX. Because the survival probability of a newt (and thus fitness) is affected by individual TTX concentration, selection can drive the escalation of toxin levels in newts. The variable fitness consequences associated with both TTX levels of newts and resistance to TTX in snakes that may promote a strong and symmetrical coevolutionary relationship have now been demonstrated.     

Species and distribution of rare earth elements in the Baotou section of the Yellow River in China

This paper analyses the contents and species distributions of rare earth elements (REEs) in the water-suspended particulate-sediment system of the Baotou section of the Yellow River, China, with known anthropogenic REE input from industrial discharges. The major forms of REEs were suspended and dissolved in the mainstream and the tributaries of the Baotou section, respectively. The concentrations of the dissolved and suspended REEs had the same trends in the overlying water along the mainstream, which increased from the Seqi section (site A) to the mouth of the Sidaosha River (site D), reaching a maximum value at site D, and tending to decrease thereafter. The contents of REEs in sediment cores showed enrichment with light rare earth elements (LREEs). The bound to carbonates and to Fe–Mn oxides are the major forms of REE in the secondary phase and the REE exhibited LREE enrichment pattern and moderate Eu depletion in suspended particulates and surface sediments. The contents and species distributions of REEs in the water-suspended particulate-sediment system of the Baotou section suggest that the anthropogenic source of REEs from Baotou city have enhanced REE accumulation to the Baotou section. This information is important for predicting possible pollution resulting from anthropogenic REE input into rivers.