Gravity variations along the Southeast Bohol Ophiolite Complex (SEBOC), Central Philippines: Implications on Ophiolite Emplacement

Abstract The basement complex of Bohol Island consists of the Southeast Bohol Ophiolite Complex (SEBOC), Cansiwang Melange and Alicia Schist. The SEBOC is a complete, but dismembered ophiolite with outcrops generally trending northeast– southwest and dipping north-west. The harzburgite units of the SEBOC are almost always observed to be thrusted onto the Cansiwang Melange, which in turn is thrusted onto the Alicia Schist. Bouguer gravity values on Bohol range from about +60 mGal in the west to +120 mGal in the east, in the region to the north-east of the SEBOC outcrops. Based on the present distribution of the SEBOC units and their thrust fault relationship with the Cansiwang Melange and Alicia Schist, it is proposed that the SEBOC was emplaced by onramping towards the south-eastward direction. However, the orientation of the Bouguer highs suggests that the thrusting direction of the ophiolite units is towards the south-west and not towards the south-east.     

Response of the bacterial community to in situ bioremediation of organic-rich sediments

A field trial experiment was carried out to assess the potential of bioremediation for mobilisation of carbon in organic-rich sediments. Both bioaugmentation (bio-fixed microorganisms) and biostimulation (oxygen release compounds--ORC) protocols have been tested and the response of the bacterial community has been described to assess the baseline for bioremediation potential. Multifactorial ANOVA revealed that bioaugmentation protocol had an effect in stimulate mobilisation processes and significantly enhanced extra-cellular enzymatic activity rates. In contrast biostimulation treatment did not have an effect on mobilisation rates but contributed to enhance bacterial efficiency through a maximization of the bacterial production:enzymatic activity ratio. Average calculation of net mobilised carbon showed that 23% increase of mobilised pool was accounted for bioaugmentation in summer. Although biostimulation accounted for a smaller increase in mobilised carbon (<10%), the use of ORC resulted in an increased mineralisation and net carbon loss via respiration. Based on our results, a conceptual model for application of bioremediation to face the problem of sediment eutrophication is discussed.     

The logistics of household hurricane evacuation

Although there is a substantial amount of research on households’ hurricane evacuation decision making, there is much less research on the logistical issues involved in implementing those evacuations. The limited research on household evacuation logistics has consistently shown that most evacuees stay in the homes of friends and relatives or in commercial facilities rather than in public shelters. However, evacuation logistics—which can be defined as the activities and associated resources needed to reach a safe location and remain there until it is safe to return—encompasses a much broader range of behaviors than this. The present study extends previous research by reporting data on other aspects of evacuation logistics such as departure timing, vehicle use, evacuation routes, travel distance, shelter type, evacuation duration, and evacuation cost. Hurricane Lili evacuation data at the county level are generally consistent with the data from previous hurricanes, but there is notable variation across counties studied here. There were only modest correlations of demographic and geographic variables with the evacuation logistics variables, a result that indicates further research is needed to better understand what happens between the time an evacuation decision is made and the time re-entry is begun. Moreover, research is needed to understand the logistics of evacuation by special populations such as transients and households with disabled members.     

The 2007 dry spell in Luzon (Philippines): its cause, impact and corresponding response measures

Climate change, involving both human-induced global warming and natural climate variability, has been called upon to explain the occurrences of weather extremes with their associated natural hazards. The Philippines experienced a dry spell in 2007 specifically in parts of Luzon which occurred during the rainy season. On the other hand, areas in Mindanao, southern Philippines which were supposed to be dry, were wet due to the non-migration of the inter-tropical convergence zone northward. The 2007 dry spell in Luzon, northern Philippines affected the agricultural, power, water and health sectors. The local effects of this weather extreme have to be documented and studied to ensure that the appropriate response measures are adopted should there be a recurrence. The building up of the database on this weather extreme and related natural hazards will definitely help the country cope with future similar events.     

Taxonomic sufficiency for soft-bottom sublittoral mollusks assemblages in a tropical estuary, Guanabara Bay, Southeast Brazil

Guanabara Bay (GB) is considered to be one of the most polluted environments of the southern Brazilian coastline. This typical estuarine system is impacted by the heavy discharge of both industrial and domestic waste from the Rio de Janeiro metropolitan area. The mollusc community structure and distribution was investigated between 2000 and 2001, using a three month sampling design of 38 stations, according to austral seasons. Species abundance was aggregated into progressively higher taxa matrices (genus, family, order) and were analysed using multivariate techniques. Mollusc distribution in GB varied significantly in space and time and was probably ruled by the organic enrichment effects of hypoxia and altered redox conditions coupled with prevailing patterns of circulation. Within the sectors of GB an increasing gradient in mollusc diversity and occurrence was observed, ranging from the azoic and impoverished stations in the inner sector to a well-structured community in terms of species composition and abundance inhabiting the outer sector. The non-metric multidimensional scaling (nMDS) and cluster analysis showed similar results when species were aggregated into genera and families, while greater difference occurred at coarser taxonomic identification (order). The literature about taxonomic sufficiency has demonstrated that faunal patterns at different taxonomic levels tend to become similar with increased pollution. In Guanabara Bay, an analysis carried out solely at family level is perfectly adequate to describe the ecophysiological stress. Further aggregation to order level changed the perceived patterns of differences. However, a different taxonomic resolution can be chosen depending on the type of ecological patterns investigated.     

The Econo-techno-social Design of Invasive Animal Management: costs and benefits or beneficiaries and benefactors?

This paper examines invasive animal management institutions, using theories at the interstices of anthropology and geography, to question current approaches to management based on neoclassical and neoliberal economic rationales. I present an analysis of two feral pig management regimes in Far North Queensland, Australia: (i) bounty systems of payment for feral pig control; and (ii) a community-based feral pig trapping program. I show how these management methods reshape important social and cultural processes through their overlapping technological and economic elements. On the basis of this analysis, I propose a conceptual framework for invasive animal management planning that incorporates a beneficiary–benefactor analysis alongside cost–benefit analyses. I argue that ecological-economic theories of pest management may be usefully enhanced by addressing the links between economic and social behaviours.     

Eutrophication and salinization of urban and rural kettle lakes in Kalamazoo and Barry Counties,Michigan, USA

Salinization and eutrophication caused by runoff of road salt and nutrients was assessed in three kettle lakes, two (Woods and Asylum Lakes) located in urban Kalamazoo, MI, and one (Brewster Lake) in rural Hastings, MI. Profiles of dissolved O₂, conductivity, pH, and temperature were measured in situ, at half meter intervals. Water samples were collected at discrete depth intervals of 1 m and analyzed for Fe(II), Mn(II), ammonium, alkalinity, Cl^?, Na, Mg, K and Ca. Results of this study indicate that all three lakes are eutrophic with anoxic bottom waters. Conductivity was much greater, and Cl^? levels were more than 100 times greater, in the two urban lakes compared to the rural lake, demonstrating the significant impact of road salt deicers on urban lake water chemistry.     

Crustal thickness and adakite occurrence in the Philippines: Is there a relationship?

Adakites are increasingly being recognized worldwide in a variety of tectonic settings. Models on the formation of this geochemically distinct class of volcanic rocks have evolved from partial melting of subducted young, hot oceanic slabs to magmatism resulting from oblique subduction, low‐angle or flat subduction, or even slab‐tearing. Some workers have also pointed to the partial melting of thickened crust to explain the generation of adakitic melts. Rare earth element ratios from adakites and adakitic rocks in the Philippines were used in this study to obtain approximations of the levels where they were generated. These were tied to available geophysical data that defines the crustal thickness of the areas where the samples were collected. High Sm/Yb and La/Yb ratios denote the involvement of amphiboles, and in some cases garnet, in the generation of adakites and adakitic magmas. The presence of amphibole and garnet as residual phases suggests high pressures corresponding to thicker crust (～30 to 45 km). Adakites and adakitic rocks formed through processes other than melting of subducted young oceanic crust would need ≥30 km to account for the heavy rare earth element signatures. If mantle fractionation is not the process involved, crustal thickness is critical to generate adakites and adakitic rocks.