Trophic Resource Utilization by Three Species of Sciaenid Fishes in a Northwest Florida Estuary

Food habits of Atlantic croaker (Micropogonias undulatus), spot (Leiostomus xanthurus), and sand seatrout (Cynoscion arenarius) were examined in 1976 collections from Apalachicola Bay, Florida. Ontogenetic, spatial, and temporal aspects of diet were considered. Polychaetes were the main food of croakers over all collections, followed in importance by detritus, fishes, insect larvae, mysids, and infaunal shrimp. Diet specialization occurred with growth of croakers, so that one or two food types dominated the diet. Intraspecific diet correlation using the Spearman Rank Correlation Coefficient, indicated three feeding groups: 10-39 mm fish, 40-39 mm fish, and 90-159 mm fish. Croaker feeding in shallow, low salinity sites in the estuary was distinct from feeding in deeper, more saline areas. Temporal analysis (January-September) of the croaker diet reflected four feeding patterns: (1) first entry into the estuary by small size fauna; (2) area-wide distribution of many size classes, (3) concentration of mid-sized individuals in the upper estuarine areas, and (4) emigration of large size classes. Polychaetes and harpacticoid copepods dominated the average spot diet, followed by detritus, bivalves and nematodes. Several distinctive patterns in feeding were noted on ontogenetic and spatial bases, but not on a temporal basis. Intraspecific diet correlation indicated similar feeding patterns in all but the smallest (20-29 mm) and largest (100-109 mm) size classes examined. Juvenile fishes (mainly Anchoa mitchilli) dominated the sand seatrout diet, while mysids ranked a distant second. There was a clear sequence of ontogenetic changes in sand seatrout feeding (also indicated by intraspecific correlation), wherein smaller size classes preyed heavily on mysids followed by a switch to piscivory by larger individuals. Spatial analysis indicated heavy consumption of fishes by sand seatrout near high salinity passes to the estuary, grading into heavy consumption of mysids in shallow, low salinity areas. Temporal analysis (May-November) revealed relatively lower predation on fishes in late summer when various crustaceans were important diet components. Interspecific diet comparisons indicated little overall trophic overlap among the three sciaenids, but diets of small croakers (10-59 mm) and spot (20-79 mm) were significantly correlated. Few correlations in diet were found between sand seatrout and either croaker or spot. A sieve fractionation technique used to analyze food habits yielded a clear distinction in prey size between the two benthic feeders. While diets were superficially similar, croakers consumed larger polychaetes and larger food items in general than did spot

Three New Species of Melita (Crustacea: Amphipoda), with Notes on the Amphipod Fauna of the Apalachicola Estuary of Northwest Florida

Three undescribed species of Melita have been collected in the Apalachicola estuary of northwest Florida. These new species, Melita elongata, M. longisetosa, and M. intermedia, are similar to and co-occur with M. nitida Smith, 1873, along the U.S. Gulf Coast. The new species of the nitida complex are yet unknown on the Atlantic coast north of Florida, although M. nitida occurs north to the Gulf of St. Lawrence. A key to the males of the species in the M. nitida complex is given. Nineteen other amphipod species have been collected in the Apalachicola estuary, six of which are at present undescribed. The life history, abundance patterns and ecological attributes are given for each species to the limit of available information

Quantitative patterns in drone wars

Attacks by drones (i.e., unmanned combat air vehicles) continue to generate heated political and ethical debates. Here we examine the quantitative nature of drone attacks, focusing on how their intensity and frequency compare with that of other forms of human conflict. Instead of the power-law distribution found recently for insurgent and terrorist attacks, the severity of attacks is more akin to lognormal and exponential distributions, suggesting that the dynamics underlying drone attacks lie beyond these other forms of human conflict. We find that the pattern in the timing of attacks is consistent with one side having almost complete control, an important if expected result. We show that these novel features can be reproduced and understood using a generative mathematical model in which resource allocation to the dominant side is regulated through a feedback loop.Comment: 5 pages, 3 figure

Uptake, metabolism, and distribution of DDT in organs of the blue crab, Callinectes sapidus

Metabolites of DDT were detected in five out of six major organs of blue crabs, Callinectes sapidus, taken from estuarine populations. Residue concentrations were highest in the hepatopancreas and below the limit of detection in the heart. Concentrations in pooled gonad samples (ovaries + testes) depended on the stage of development of the ovaries. Residue levels were low in claw and backfin muscles. Adult blue crabs were exposed for 12 hours to 0.01, 0.1, and 1.0 ppm DDT in water. No significant mortality was recorded. DDT was absorbed through the gills and transported to the hepatopancreas via the hemolymph. Biotransformation and distribution of DDT and its metabolites was regulated by the hepatopancreas. Induction of metabolic transformation of DDT to DDD and DDE occurred immediately. Storage of residues was greatest in the hepatopancreas and developing ovaries . Rates of loss of DDT residues from organs was subject to considerable variation. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia

Social media usage patterns during natural hazards

Natural hazards are becoming increasingly expensive as climate change and development are exposing communities to greater risks. Preparation and recovery are critical for climate change resilience, and social media are being used more and more to communicate before, during, and after disasters. While there is a growing body of research aimed at understanding how people use social media surrounding disaster events, most existing work has focused on a single disaster case study. In the present study, we analyze five of the costliest disasters in the last decade in the United States (Hurricanes Irene and Sandy, two sets of tornado outbreaks, and flooding in Louisiana) through the lens of Twitter. In particular, we explore the frequency of both generic and specific food-security related terms, and quantify the relationship between network size and Twitter activity during disasters. We find differences in tweet volume for keywords depending on disaster type, with people using Twitter more frequently in preparation for Hurricanes, and for real-time or recovery information for tornado and flooding events. Further, we find that people share a host of general disaster and specific preparation and recovery terms during these events. Finally, we find that among all account types, individuals with “average” sized networks are most likely to share information during these disasters, and in most cases, do so more frequently than normal. This suggests that around disasters, an ideal form of social contagion is being engaged in which average people rather than outsized influentials are key to communication. These results provide important context for the type of disaster information and target audiences that may be most useful for disaster communication during varying extreme events

Simon\u27s fundamental rich-get-richer model entails a dominant first-mover advantage

Herbert Simon\u27s classic rich-get-richer model is one of the simplest empirically supported mechanisms capable of generating heavy-tail size distributions for complex systems. Simon argued analytically that a population of flavored elements growing by either adding a novel element or randomly replicating an existing one would afford a distribution of group sizes with a power-law tail. Here, we show that, in fact, Simon\u27s model does not produce a simple power-law size distribution as the initial element has a dominant first-mover advantage, and will be overrepresented by a factor proportional to the inverse of the innovation probability. The first group\u27s size discrepancy cannot be explained away as a transient of the model, and may therefore be many orders of magnitude greater than expected. We demonstrate how Simon\u27s analysis was correct but incomplete, and expand our alternate analysis to quantify the variability of long term rankings for all groups. We find that the expected time for a first replication is infinite, and show how an incipient group must break the mechanism to improve their odds of success. We present an example of citation counts for a specific field that demonstrates a first-mover advantage consistent with our revised view of the rich-get-richer mechanism. Our findings call for a reexamination of preceding work invoking Simon\u27s model and provide an expanded understanding going forward

Evaluation of a Bayesian inference network for ligand-based virtual screening

Background Bayesian inference networks enable the computation of the probability that an event will occur. They have been used previously to rank textual documents in order of decreasing relevance to a user-defined query. Here, we modify the approach to enable a Bayesian inference network to be used for chemical similarity searching, where a database is ranked in order of decreasing probability of bioactivity. Results Bayesian inference networks were implemented using two different types of network and four different types of belief function. Experiments with the MDDR and WOMBAT databases show that a Bayesian inference network can be used to provide effective ligand-based screening, especially when the active molecules being sought have a high degree of structural homogeneity; in such cases, the network substantially out-performs a conventional, Tanimoto-based similarity searching system. However, the effectiveness of the network is much less when structurally heterogeneous sets of actives are being sought. Conclusion A Bayesian inference network provides an interesting alternative to existing tools for ligand-based virtual screening

Health equity in the New Zealand health care system: a national survey

<p>Abstract</p> <p>Introduction</p> <p>In all countries people experience different social circumstances that result in avoidable differences in health. In New Zealand, Māori, Pacific peoples, and those with lower socioeconomic status experience higher levels of chronic illness, which is the leading cause of mortality, morbidity and inequitable health outcomes. Whilst the health system can enable a fairer distribution of good health, limited national data is available to measure health equity. Therefore, we sought to find out whether health services in New Zealand were equitable by measuring the level of development of components of chronic care management systems across district health boards. Variation in provision by geography, condition or ethnicity can be interpreted as inequitable.</p> <p>Methods</p> <p>A national survey of district health boards (DHBs) was undertaken on macro approaches to chronic condition management with detail on cardiovascular disease, chronic obstructive pulmonary disease, congestive heart failure, stroke and diabetes. Additional data from expert informant interviews on program reach and the cultural needs of Māori and Pacific peoples was sought. Survey data were analyzed on dimensions of health equity relevant to strategic planning and program delivery. Results are presented as descriptive statistics and free text. Interviews were transcribed and NVivo 8 software supported a general inductive approach to identify common themes.</p> <p>Results</p> <p>Survey responses were received from the majority of DHBs (15/21), some PHOs (21/84) and 31 expert informants. Measuring, monitoring and targeting equity is not systematically undertaken. The Health Equity Assessment Tool is used in strategic planning but not in decisions about implementing or monitoring disease programs. Variable implementation of evidence-based practices in disease management and multiple funding streams made program implementation difficult. Equity for Māori is embedded in policy, this is not so for other ethnic groups or by geography. Populations that conventional practitioners find hard to reach, despite recognized needs, are often underserved. Nurses and community health workers carried a disproportionate burden of care. Cultural and diversity training is not a condition of employment.</p> <p>Conclusions</p> <p>There is a struggle to put equity principles into practice, indicating will without enactment. Equity is not addressed systematically below strategic levels and equity does not shape funding decisions, program development, implementation and monitoring. Equity is not incentivized although examples of exceptional practice, driven by individuals, are evident across New Zealand.</p