Ocean resource use: building the coastal blue economy

Reviews in Fish Biology and Fisheries - Humans have relied on coastal resources for centuries. However, current growth in population and increased accessibility of coastal resources through...     

Does whole‐organism performance constrain resource use? A community test with desert lizards

Discovering the mechanisms by which communities of co‐existing species exist has proven to be one of the greatest challenges for evolutionary ecologists. A recent perspective emphasizes the role of functional traits, such as whole‐organism performance, as key limiting factors in the evolution of communities, yet few studies have examined this possibility. We examine how bite force and morphology influence the ability of ten lizard species in a single community to access insect prey, as defined by prey type and prey hardness. We gathered over 3 years of data from a desert lizard community comprised of ten species and found significant variation among species for bite force and prey hardness, as well as significant differences in performance and niche breadth for each species. In general, higher levels of absolute bite force broadens resource accessibility (sizes of prey), and does not generally result in a reduced ability to access smaller prey. For example, large lizard species that are hard biters can still consume soft prey. On the other hand, small lizard species that are weak biters are more limited in their ability to access hard prey, although the overall decline in resource accessibility is modest. Our findings highlight how functional traits can influence which species can access key resources within a community of similar species. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●● , ●●–●●.     

Effects of heterogeneous and clustered contact patterns on infectious disease dynamics

The spread of infectious diseases fundamentally depends on the pattern of contacts between individuals. Although studies of contact networks have shown that heterogeneity in the number of contacts and the duration of contacts can have far-reaching epidemiological consequences, models often assume that contacts are chosen at random and thereby ignore the sociological, temporal and/or spatial clustering of contacts. Here we investigate the simultaneous effects of heterogeneous and clustered contact patterns on epidemic dynamics. To model population structure, we generalize the configuration model which has a tunable degree distribution (number of contacts per node) and level of clustering (number of three cliques). To model epidemic dynamics for this class of random graph, we derive a tractable, low-dimensional system of ordinary differential equations that accounts for the effects of network structure on the course of the epidemic. We find that the interaction between clustering and the degree distribution is complex. Clustering always slows an epidemic, but simultaneously increasing clustering and the variance of the degree distribution can increase final epidemic size. We also show that bond percolation-based approximations can be highly biased if one incorrectly assumes that infectious periods are homogeneous, and the magnitude of this bias increases with the amount of clustering in the network. We apply this approach to model the high clustering of contacts within households, using contact parameters estimated from survey data of social interactions, and we identify conditions under which network models that do not account for household structure will be biased.     

Detrimental effects of environmental tobacco smoke in relation to asthma severity

Background

Environmental tobacco smoke (ETS) has adverse effects on the health of asthmatics, however the harmful consequences of ETS in relation to asthma severity are unknown.

Methods

In a multicenter study of severe asthma, we assessed the impact of ETS exposure on morbidity, health care utilization and lung functions; and activity of systemic superoxide dismutase (SOD), a potential oxidative target of ETS that is negatively associated with asthma severity.

Findings

From 2002–2006, 654 asthmatics (non-severe 366, severe 288) were enrolled, among whom 109 non-severe and 67 severe asthmatics were routinely exposed to ETS as ascertained by history and validated by urine cotinine levels. ETS-exposure was associated with lower quality of life scores; greater rescue inhaler use; lower lung function; greater bronchodilator responsiveness; and greater risk for emergency room visits, hospitalization and intensive care unit admission. ETS-exposure was associated with lower levels of serum SOD activity, particularly in asthmatic women of African heritage.

Interpretation

ETS-exposure of asthmatic individuals is associated with worse lung function, higher acuity of exacerbations, more health care utilization, and greater bronchial hyperreactivity. The association of diminished systemic SOD activity to ETS exposure provides for the first time a specific oxidant mechanism by which ETS may adversely affect patients with asthma.     

Growth and multiplication ofRhodotorula glutinis as determined by viable and total cell counts

Excellent correlation has been shown between two total and two culture, or viable, count techniques used for cell enumeration studies ofRhodotorula glutinis. The culture methods examined, the drop plate and the spread plate proved equally reliable for enumeration except for slight variations during the period of maximal budding of the organism. The Coulter Counter was a valuable tool as it permitted rapid cell population analysis with minimal preparatory procedures. The Petroff-Hausser counting chamber was found applicable only when cell numbers approached 10⁹ or greater.Contribution No. 468 from the Marine Laboratory, Institute of Marine Science, University of Miami, Miami, Florida, U.S.A. Supported by Grant G-16146 from the National Science Foundation.