Settlement-competency periods of larvae of three species of scleractinian corals

The pattern of settlement over time of three broadcast spawning coral species (Cyphastrea serailia, Acanthastrea lordhowensis, and Goniastrea australensis) from the Solitary Islands (30°00′S; 153°20′E) was studied in 1995 and 1996 in order to determine the maximum length of time these larvae could remain in the water column and still retain the ability to settle and metamorphose. Larvae were maintained in aquaria and the number which had settled on biologically-conditioned tile pairs was monitored every 5 to 10 d. While the majority of larvae settled quickly after becoming competent, some larvae survived and settled for extended periods after spawning. Competency periods ranged from 26 d for C. serailia to 56 d for G. australensis and 78 d for A. lordhowensis. These data greatly extend the known competency periods for larvae of broadcast-spawning corals and indicate the potential for transport of broadcast-spawned coral larvae over large distances. Medium to long-distance larval dispersal of the species studied provides a mechanism for their widespread distribution in subtropical regions, on reefs which are often widely spaced and relatively isolated. Received: 27 May 1997 / Accepted: 27 November 1997     

Using variance components to estimate power in a hierarchically nested sampling design

We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007–2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of yearly differences in the power of the survey. Results indicated that increasing the sample size at the lowest level of sampling represented the most realistic option to increase the survey’s power, fixed plot designs had greater power than random plot designs, and the power of the larval survey varied by year. This study provides an example of how monitoring efforts may benefit from coupling variance components estimation with power analysis to assess sampling design.     

Rate of occurrence of failures based on a nonhomogeneous Poisson process: an ozone analyzer case study

Atmospheric pollutant monitoring constitutes a primordial activity in public policies concerning air quality. In São Paulo State, Brazil, the São Paulo State Environment Company (CETESB) maintains an automatic network which continuously monitors CO, SO₂, NO _x , O₃, and particulate matter concentrations in the air. The monitoring process accuracy is a fundamental condition for the actions to be taken by CETESB. As one of the support systems, a preventive maintenance program for the different analyzers used is part of the data quality strategy. Knowledge of the behavior of analyzer failure times could help optimize the program. To achieve this goal, the failure times of an ozone analyzer—considered a repairable system—were modeled by means of the nonhomogeneous Poisson process. The rate of occurrence of failures (ROCOF) was estimated for the intervals 0–70,800 h and 0–88,320 h, in which six and seven failures were observed, respectively. The results showed that the ROCOF estimate is influenced by the choice of the observation period, t ₀?=?70,800 h and t ₇?=?88,320 h in the cases analyzed. Identification of preventive maintenance actions, mainly when parts replacement occurs in the last interval of observation, is highlighted, justifying the alteration in the behavior of the inter-arrival times. The performance of a follow-up on each analyzer is recommended in order to record the impact of the performed preventive maintenance program on the enhancement of its useful life.     

Mathematical Modeling of Column and Field Dense Nonaqueous Phase Liquid Tracer Tests

Mathematical models for the simulation of dense nonaqueous phase liquid tracer tests (DTTs) in laboratory columns and in the field are developed and examined. The DTT technique is a means of estimating the quantity of dense nonaqueous phase liquid (DNAPL) in a domain of interest in an aquifer. The two-dimensional field DTT model uses the Method of Principal Directions and an asymmetrical upwind algorithm for describing advective transport. Both models include diffusion transport of tracer into and from low-permeability porous structures such as clay lenses, as well as the mass transport kinetics of partitioning tracer to and from the DNAPL droplets. The dependence of the effluent tracer concentration curves on the parameters of the models is explored, and conclusions are drawn regarding the applicability of, and several possible problems with, the DTT technique. Model results indicate that the DTT performs well at locating distributed droplets of DNAPL, but is unlikely to be useful in the assessment of pooled DNAPL.     

Air Pollution and Health

The use of multistage, dry, fluidized beds of continuously recycled, coal-based activated carbon appears technically and economically attractive for both adsorption of stack gas So₂ and sequential conversion to elemental sulfur. Conceptual design details and economic factors are discussed for the treatment of power plant or oil refinery SO₂ effluents with by-product sulfur recovery.     

Removal of Volatile Aliphatic Hydrocarbons in a Soil Bioreactor

Soil removal of propane, isobutane and n-butane from a waste air stream was evaluated in the laboratory and in a prototype soil bioreactor. Laboratory investigations indicated first-order kinetics and the potential to degrade light aliphatic hydrocarbons and trichlorethylene, a compound ordinarily resistant to aerobic biological treatment. The predicted behavior of the bioreactor, based on laboratory studies, agreed closely with the actual behavior of the Reid system. The prototype bioreactor reduced the hydrocarbon concentrations in the air by at least 90percent with a residence time of 15 minutes and a pressure drop of 85 cm of water. The bioreactor functioned well through a range of temperatures, 12°C to 24°C.     

Biomonitoring of heavy metals in the feathers of House crow (Corvus splendens) from some metropolitans of Asia and Africa

Environmental Science and Pollution Research - Urban-dwelling birds can be useful biomonitors to assess the impact of the urbanisation on both public and wildlife health. Widely distributed urban...     

A game theoretic approach to multimodal communication

Over the last few decades the animal communication community has become increasingly aware that much communication occurs using multiple signals in multiple modalities. The majority of this work has been empirical, with less theoretical work on the advantages conferred by such communication. In the present paper, we ask: Why should animals communicate with multiple signals in multiple modalities? To tackle this question we use game theoretic techniques, and highlight developments in the economic signaling literature that might offer insight into biological problems. We start by establishing a signaling game, and investigate signal honesty under two prevailing paradigms of honest communication – costly signaling and cheap talk. In both paradigms, without further constraint, it is simple to show that anything that can be achieved with multiple signals can be achieved with one. We go on to investigate different sets of possible constraints that may make multiple signals and multimodal signals in particular more likely to evolve. We suggest that constraints on cost functions and bandwidths, orthogonal noise across modalities, strategically distinct modes, multiple qualities, multiple signalers, and multiple audiences, all provide biologically plausible scenarios that theoretically favor multiple and multimodal signaling.