Coral architecture affects the habitat choice and form of associated gobiid fishes

Gobiid fishes of the genus Gobiodon live in strong association with certain reef-building corals that vary considerably in size and architecture. These fishes hence are excellent model systems for studying evolutionary adaption to specific microhabitats. Using a sample of Gobiodon histrio and G. rivulatus and their most important host corals (Acropora digitifera and A. gemmifera) from the northern Red Sea, we assess (1) how corals that are occupied by gobies differ in their architecture from colonies that are not occupied and (2) how fish body shape is associated with the architecture of their host coral. Fish body shape was assessed by geometric morphometric techniques. Coral measurements included colony size, branch length (BL), and interbranch as well as branch tip distance of adjacent branches, for which we applied a new and non-destructive measurement technique based on casts of two-component epoxy resin. The most important factor influencing the occupation of corals was a BL of more than 5 cm. The distance between coral branches was clearly related to the width of the fishes and hence constrained overall fish size. G. histrio and G. rivulatus differ in adult body shape as well in their allometric development of lateral body compression, resulting in different maximum body sizes attainable in the restricted interbranch space of corals. The strong dependence of coral-associated fishes on large coral colonies with specific architectures increases the extinction risk of fishes within deteriorating coral reefs.     

MULTICRITERION ANALYSIS OF GROUNDWATER CONTAMINATION MANAGEMENT1

ABSTRACT: Multicriterion decision making (MCDM) techniques were used to analyze a groundwater contamination management problem from the viewpoint of conflicting multiple objectives. The groundwater management model was used to find a compromise strategy for trading off fresh water supply, containment of the waste, and total pumping cost in a hypothetical confined aquifer affected by previous waste disposal action. A groundwater flow model was used to formulate the hydraulic constraints. A linear system model was used to describe drawdown and velocity as functions of the decision variables which were pumping rates. The model determines the pumping location and rates. A modified c-constraint method was used to generate the set of nondominated solutions which were the alternative compromise strategies. Three different MCDM techniques, Compromise programming (CP), ELECTRA II and MCQA II, were used to select a “satisficing” alternative. Analysis of the results showed that, although these techniques follow different principles, the same preferred strategies were reached. Also, it was noticed that maintaining high groundwater velocities is expensive and difficult. In order to meet a two year target date, large amounts of water had to be pumped. Therefore, rapid restoration results in large pumping volumes and high costs.     

EFFICIENCY OF HYDROLOGIC DATA COLLECTION SYSTEMS ROLE OF TYPE I AND II ERRORS1

ABSTRACT The efficiency of hydrologic data collection systems is relevant to solution of environmental problems, scientific understanding of hydrologic processes, model-building and management of water resources. Because these goals may be overlapping and non-commensurate, design of data networks is not simple. Identified are four elements of error or risk in such networks: (a) choice of variables and mathematical model for the same process, (b) accuracy of model parameter estimates, (c) acceptance of wrong hypothesis or rejection of correct hypothesis and (d) economic losses associated with error. Of these four, the classical hypothesis testing problem is specifically evaluated in terms of costs of type I and II errors for simple and composite hypotheses; mathematical models for these economic analyses also include costs of sample data and costs of waiting while new data is obtained. An illustrative computational example focuses on the hypothesis that natural recharge might be augmented by a system of pumping wells along an ephemeral channel. The relationship of the hypothesis testing problem to Bayesian decision theory is discussed; it is felt that the latter theory offers a more comprehensive framework for design and use of hydrologic data networks.     

THE USE OF MULTIPLE REGRESSION MODELS IN PREDICTING SEDIMENT YIELD1

ABSTRACT. Four commonly used models for predicting sediment yield are analyzed and compared using previously published data. Three of these models involve logarithmic transformations. Some of the problems involved in transforming data are discussed in the context of logarithmic transformations. These problems are illustrated using the results of standard regression analyses and economic loss function analyses. For the data analyzed, the linear model is preferable to each of the logarithmic models on the basis of each analysis, and the usual multiple objective nature of the model choice problem is thus modified. The extent to which these results can be generalized is discussed in the context of model choice.     

SAMPLE UNCERTAINTY IN FLOOD LEVEE DESIGN: BAYESIAN VERSUS NON-BAYESIAN METHODS1

ABSTRACT: Bayesian and non-Bayesian flood levee design methods that account for the uncertainty due to limited record length are compared using a case study. The first method, Bayesian decision theory (BDT), imbeds the uncertainty in the parameters of the yearly peak stage into a loss function. The optimum design of the flood levee, called Bayes design, corresponds to the minimum expected loss, called Bayes risk. The second method, induced safety algorithm (ISA), computes a margin of safety to be added to either an existing levee or a levee designed by classical benefit-cost analysis. The design decision is shown to fluctuate as different record lengths are considered. For short record lengths, BDT, which takes small sample bias into account, appears to yield a more conservative design than ISA. On the other hand, ISA, which is simple to implement, seems to be preferable to BDT for longer record lengths.     

INTERACTIVE MULTIOBJECTIVE ANALYSIS EMBEDDING THE DECISION MAKER'S IMPLICIT PREFERENCE FUNCTION1

ABSTRACT: Two simple interactive techniques are developed and illustrated by means of two different real-life examples in Thailand. The first technique, Evolutionary Sequential Multiobjective Problem Solving (ESEMOPS), is an open-ended algorithm designed for planning problems with discrete alternatives. ESEMOPS helps the decision making group (DMG) develop progressively a preference function over the alternatives. The algorithm follows an evolutionary “breeding” strategy to generate a small set of good alternative solutions. This heuristic search, which does not guarantee that the adopted ‘satisfactum’ is an efficient solution leads to plausible results when applied to the planning of the Mae Khlong-Chao Phraya interbasin water transfer and irrigation system. The second algorithm, Search Beam Method (SBM) is essentially a series of one-dimensional searches for an efficient point along a “beam” passing through a goal point. Repeated search towards displayed goal points is leading to a set of quasi non-dominated solutions. SBM is illustrated by the Ubol Ratana reservoir control problem with the two conflicting objectives of energy generation and irrigation water supply. Neither ESEMOPS nor SBM require that weights, utilities, or pairwise tradeoffs be assessed. These features have been very much appreciated by a real DMG presented with the two techniques.     

Simultaneous Concentration of Enteric Viruses and Protozoan Parasites: A Protocol Based on Tangential Flow Filtration and Adapted to Large Volumes of Surface and Drinking Waters

A filtration system, based on tangential flow filtration (TFF) followed by ultracentrifugation was developed in order to concentrate simultaneously viruses and parasites from large volumes of water. For TFF, no pre-treatment of the membrane is performed but a post-rinsing step using high pH-beef extract-based eluant. Applying our protocol to 20 l of surface waters spiked with vaccinal poliovirus-1, ϕX174 and MS2 bacteriophages resulted in an averaged viral recovery of 75% by TFF and 91% by ultracentrifugation (total viral recovery of 70%). Our protocol was further applied to 31 environmental samples including surface, ground and drinking waters from the Grand Duchy of Luxembourg in order to assess the occurrence of protozoan parasites (Cryptosporidium parvum and Giardia lamblia (oo)cysts), pathogenic viruses (enterovirus, norovirus and adenovirus) and infectious bacteriophages (somatic coliphages and F-specific phages) in these samples. High viral recovery rates of > 70% were confirmed concentrating environmental strains of somatic and F-specific coliphages from non-spiked surface waters. Parasites and enteric viruses were detected in 86 and 40% of the surface waters used for drinking water production, respectively. Infectious bacteriophages were isolated from all surface waters and in two out of seven (29%) groundwaters revealing a susceptibility of the corresponding wells to viral pollution. TFF-based method proved to be efficient for surveying the occurrence of non-bacterial pathogens such as enteric viruses and protozoan parasites in large volumes of environmental waters.     

Applicability of energy-positive net-zero water management in Alaska: technology status and case study

Challenges of water and wastewater management in Alaska include the potential need for above-grade and freeze-protected piping, high unit energy costs and, in many rural areas, low population density and median annual income. However, recently developed net-zero water (NZW), i.e., nearly closed-loop, direct potable water reuse systems, can retain the thermal energy in municipal wastewater, producing warm treated potable water without the need for substantial water re-heating, heat pumping or transfer, or additional energy conversion. Consequently, these systems are projected to be capable of saving more energy than they use in water treatment and conveyance, in the temperate USA. In this paper, NZW technology is reviewed in terms of potential applicability in Alaska by performing a hypothetical case study for the city of Fairbanks, Alaska. Results of this paper study indicate that in municipalities of Alaska with local engineering and road access, the use of NZW systems may provide an energy-efficient water service option. In particular, case study modeling suggests hot water energy savings are equivalent to five times the energy used for treatment, much greater savings than in mid-latitudes, due largely to the substantially higher energy needed for heating water from a conventional treatment system and lack of need for freeze-protected piping. Further study of the applicability of NZW technology in cold regions, with expanded evaluation in terms of system-wide lifecycle cost, is recommended.     

Simulation of Urban-Scale Air Pollution Patterns in Luxembourg: Contributing Sources and Emission Scenarios

The aim of this study is to investigate the air pollution situation in an urban area in southwestern Luxembourg and to simulate annual NO₂ and PM₁₀ concentrations in response to changes in meteorological conditions and emissions using a Gaussian dispersion model. Simulations are carried out for the years 1998–2006. Emission scenarios related to road transport and nonindustrial combustion are performed in order to predict changes of air pollution levels. Road transport is by far the most important local emission source in the study area. Scenarios with more stringent emission standards for vehicles, less traffic, and fewer heavy-duty vehicles lead to reductions of NO_x and primary PM₁₀ emissions. As a result, the annual NO₂ concentrations are decreasing in most parts of the study area and are below the European annual limit value of 40 μg?m^?3. In contrast, a scenario with increased use of wood pellets for domestic heating shows an increase in urban PM₁₀ concentration. The year-to-year variability of meteorological conditions accounts for the same magnitude of absolute NO₂ and PM₁₀ concentration changes as the emission scenarios. The comparison with measurements located in the study area shows that the model is able to predict urban-scale annual average air pollution. The proposed application results show that the model can be appropriate for policy-driven air quality management and planning queries.