Indirect effects of species interactions on habitat provisioning

Species that shelter in a biogenic habitat can influence their refugia and, in turn, play an essential role in shaping local patterns of biodiversity. Here we explore a positive feedback loop between the provisioning rate of habitat-forming branching corals and their associated fishes and show how interactions between two groups of fish—the planktivorous damselfish and predatory hawkfish—altered the feedback. A field experiment confirmed that skeletal growth of branching coral (genus Pocillopora) increased substantially with increasing numbers (biomass) of resident fishes, likely because they greatly increased the interstitial concentrations of nutrients. Because there is a positive relationship between colony size and number (biomass) of associated fishes (primarily damselfishes in the Family Pomacentridae), a structure–function feedback loop exists in which increasing numbers of damselfish enhance coral growth and larger corals host greater abundances (and species richness) of fish. However, interactions between damselfishes and arc-eye hawkfish, Paracirrhites arcatus, a largely solitary resident, can disrupt this positive feedback loop. Field surveys revealed a marked pattern of fish occupancy related to coral size: Pocillopora colonies of sufficient size to host fish (>40 cm circumference) had either groups of damselfish or an arc-eye hawkfish; only larger colonies (>75 cm) were occupied by both the damselfish and hawkfish. Subsequent short- and long-term experiments revealed that on intermediate-sized Pocillopora colonies, arc-eye hawkfish prevented the establishment of damselfish by suppressing their recruitment. The demographic consequences to the host coral were substantial; in a 1-year-long experiment, intermediate-size Pocillopora occupied by hawkfish grew at half the rate of corals that hosted groups of damselfish. These findings indicate that: (1) species which occupy a biogenic habitat can enhance the provisioning rate of their habitat; (2) such positive feedbacks between community structure and ecosystem function can be disrupted by a strong interactor; (3) even substantial consequences on ecosystem processes that arise can be difficult to discern

A New (Old), Invasive Ant in the Hardwood Forests of Eastern North America and Its Potentially Widespread Impacts

Biological invasions represent a serious threat for the conservation of biodiversity in many ecosystems. While many social insect species and in particular ant species have been introduced outside their native ranges, few species have been successful at invading temperate forests. In this study, we document for the first time the relationship between the abundance of the introduced ant, Pachycondyla chinensis, in mature forests of North Carolina and the composition, abundance and diversity of native ant species using both a matched pair approach and generalized linear models. Where present, P. chinensis was more abundant than all native species combined. The diversity and abundance of native ants in general and many individual species were negatively associated with the presence and abundance of P. chinensis. These patterns held regardless of our statistical approach and across spatial scales. Interestingly, while the majority of ant species was strongly and negatively correlated with the abundance and presence of P. chinensis, a small subset of ant species larger than P. chinensis was either as abundant or even more abundant in invaded than in uninvaded sites. The large geographic range of this ant species combined with its apparent impact on native species make it likely to have cascading consequences on eastern forests in years to come, effects mediated by the specifics of its life history which is very different from those of other invasive ants. The apparent ecological impacts of P. chinensis are in addition to public health concerns associated with this species due to its sometimes, deadly sting

Skin Lesions on Common Bottlenose Dolphins (Tursiops truncatus) from Three Sites in the Northwest Atlantic, USA

Skin disease occurs frequently in many cetacean species across the globe; methods to categorize lesions have relied on photo-identification (photo-id), stranding, and by-catch data. The current study used photo-id data from four sampling months during 2009 to estimate skin lesion prevalence and type occurring on bottlenose dolphins (Tursiops truncatus) from three sites along the southeast United States coast [Sarasota Bay, FL (SSB); near Brunswick and Sapelo Island, GA (BSG); and near Charleston, SC (CHS)]. The prevalence of lesions was highest among BSG dolphins (P = 0.587) and lowest in SSB (P = 0.380), and the overall prevalence was significantly different among all sites (p<0.0167). Logistic regression modeling revealed a significant reduction in the odds of lesion occurrence for increasing water temperatures (OR = 0.92; 95%CI:0.906–0.938) and a significantly increased odds of lesion occurrence for BSG dolphins (OR = 1.39; 95%CI:1.203–1.614). Approximately one-third of the lesioned dolphins from each site presented with multiple types, and population differences in lesion type occurrence were observed (p<0.05). Lesions on stranded dolphins were sampled to determine the etiology of different lesion types, which included three visually distinct samples positive for herpesvirus. Although generally considered non-fatal, skin disease may be indicative of animal health or exposure to anthropogenic or environmental threats, and photo-id data provide an efficient and cost-effective approach to document the occurrence of skin lesions in free-ranging populations

Toward a Comprehensive Approach to the Collection and Analysis of Pica Substances, with Emphasis on Geophagic Materials

Pica, the craving and subsequent consumption of non-food substances such as earth, charcoal, and raw starch, has been an enigma for more than 2000 years. Currently, there are little available data for testing major hypotheses about pica because of methodological limitations and lack of attention to the problem.In this paper we critically review procedures and guidelines for interviews and sample collection that are appropriate for a wide variety of pica substances. In addition, we outline methodologies for the physical, mineralogical, and chemical characterization of these substances, with particular focus on geophagic soils and clays. Many of these methods are standard procedures in anthropological, soil, or nutritional sciences, but have rarely or never been applied to the study of pica.Physical properties of geophagic materials including color, particle size distribution, consistency and dispersion/flocculation (coagulation) should be assessed by appropriate methods. Quantitative mineralogical analyses by X-ray diffraction should be made on bulk material as well as on separated clay fractions, and the various clay minerals should be characterized by a variety of supplementary tests. Concentrations of minerals should be determined using X-ray fluorescence for non-food substances and inductively coupled plasma-atomic emission spectroscopy for food-like substances. pH, salt content, cation exchange capacity, organic carbon content and labile forms of iron oxide should also be determined. Finally, analyses relating to biological interactions are recommended, including determination of the bioavailability of nutrients and other bioactive components from pica substances, as well as their detoxification capacities and parasitological profiles.This is the first review of appropriate methodologies for the study of human pica. The comprehensive and multi-disciplinary approach to the collection and analysis of pica substances detailed here is a necessary preliminary step to understanding the nutritional enigma of non-food consumption

Modeling brake specific fuel consumption to support exploration of doubly fed electric machines in naval engineering applications

Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages [71a]-[71b]).The dynamic operational nature of naval power and propulsion requires Ship Design and Program Managers to design and select prime movers using a much more complex speed profile rather than typical of commercial vessels. The inherently reduces the overall efficiency of the plant as operated in comparison to its potential. The fuel consumption of prime movers is a multi-variable function of power demand and rotational speed. Mechanically coupled power and propulsion arrangements constrain this two degree of freedom relationship by removing the independence of the speed parameter. Fixed frequency power generation requires a constant prime mover speed that has a narrow power band for optimal fuel consumption. Likewise, geared propulsion arrangements restrict the prime mover's speed to a dependence on the combined propulsor thrust-hull resistance performance which generally follows a cubic function. Optimal fuel consumption, however, involves matching the load's efficiency performance to that of the prime mover. This requires the rotational speed of the prime mover to be an independent variable with the freedom to adjust to the lowest specific fuel consumption for the demanded power. Variable frequency drive (VFD) concepts offer relief of this constraint but at a cost in the form of increased power conversion and control support system footprints. The ever increasing and complex demands for electrical power increases the motivation and interest in innovative technologies that improving current design concepts. Incorporating doubly fed electric machines (DFEM) into the power and propulsion design architecture enables the efficiency results of a VFD system but with a smaller conversion and control support footprint. The Navy has invested resources into research and development of several electric power and propulsion technologies enabling deployment of VFD systems on a handful of ship classes. The wind power generation industry has matured many aspects of DFEM technology. Leveraging this experience into naval engineering applications could help facilitate additional platform types and sizes to benefit from the operational advantages of integrated electrical architectures. Applying DFEM concepts to naval engineering requires a horizontal transfer of the body of knowledge. Researchers in the field of DFEM technology need to gain a better understanding of the intricacies of integrating a marine vessel's engineering plant with the vessel's designed purpose. New methods of analysis tailored specifically to marine power and propulsion require development for the technology to be properly assessed. This study outlines the various issues challenging ship designers and explains the manner in which DFEM research can be continued in naval engineering. Finally a method of examining a prime mover's fuel consumption is developed to provide a three-dimensional "fuel map" surface relationship of power-to-speed-to-fuel consumption. This thesis will serve as a building block supporting further DFEM power and propulsion concept analysis.by Michael R. Rowles, Jr.Nav. E.S.M. in Naval Architecture and Marine Engineerin

Improving the biodegradability in seawater test (OECD 306)

\ua9 2019 Growth and extensive urbanisation of the human population has been accompanied by increased manufacture and use of chemical compounds. To classify the fate and behaviour of these compounds in the environment, a series of international standardised biodegradation screening tests (BSTs) were developed over 30 years ago. In recent years, regulatory emphasis (e.g. REACH) has shifted from measuring biodegradation towards prioritisations based on chemical persistence. In their current guise, BSTs are ineffective as screens for persistence. The marine BST OECD 306 in particular is prone to high levels of variation and produces a large number of fails, many of which can be considered false negatives. An ECETOC funded two-day workshop of academia, industry and regulatory bodies was held in 2015 to discuss improvements to the marine BSTs based on previous research findings from the Cefic LRI ECO11 project and other foregoing studies. During this workshop, methodological improvements to the OECD 306 test were discussed, in addition to clarifying guidance on testing and interpretation of results obtained from marine BSTs (such as pass criteria, lag phases, freshwater read across and complex substances). Methodologically: (i) increasing bacterial cell concentrations to better represent the bacterial diversity inherent in the sampled environments; and (ii) increasing test durations to investigate extended lag phases observed in marine assessments, were recommended to be validated in a multi-institutional ring test