Human activities are causing a global proliferation of cyanobacterial harmful algal blooms (CHABs), yet we have limited understanding of how these events affect freshwater bacterial communities. Using weekly data from western Lake Erie in 2014, we investigated how the cyanobacterial community varied over space and time, and whether the bloom affected non-cyanobacterial (nc-bacterial) diversity and composition. Cyanobacterial community composition fluctuated dynamically during the bloom, but was dominated by Microcystis and Synechococcus OTUs. The bloom's progression revealed potential impacts to nc-bacterial diversity. Nc-bacterial evenness displayed linear, unimodal, or no response to algal pigment levels, depending on the taxonomic group. In addition, the bloom coincided with a large shift in nc-bacterial community composition. These shifts could be partitioned into components predicted by pH, chlorophyll a, temperature, and water mass movements. Actinobacteria OTUs showed particularly strong correlations to bloom dynamics. AcI-C OTUs became more abundant, while acI-A and acI-B OTUs declined during the bloom, providing evidence of niche partitioning at the sub-clade level. Thus, our observations in western Lake Erie support a link between CHABs and disturbances to bacterial community diversity and composition. Additionally, the short recovery of many taxa after the bloom indicates that bacterial communities may exhibit resilience to CHABs.
Four hundred twenty-one consecutive patients admitted to an acute general medical ward and two acute rehabilitation medical wards were studied to compare the characteristics and outcomes of physically restrained patients and unrestrained patients. Restraints were used in 35 (13%) of the general medical patients and in 49 (34%) of the rehabilitation patients. The restrained general medical patients had higher mortality and morbidity rates than their unrestrained counterparts. Restrained patients had a higher prevalence of a psychiatric diagnosis, and major tranquilizers were used more than in their unrestrained counterparts in both settings. The general medical patients tended to have more than one type of restraint at a time, whereas the rehabilitation patients were restrained for longer proportions of their hospital stay. Thirty-three percent of the restrained patients whom we were able to interview expressed negative perceptions about the presence of the physical restraints. Moreover, it was found that the presence of cognitive and physical impairments were highly predictive of restraint use in both populations.
The interaction of crop pests with their natural enemies is a fundament to their control. Natural enemies of fungal pathogens of crops are poorly known relative to those of insect pests, despite the diversity of fungal pathogens and their economic importance. Currently, many regions across Latin America are experiencing unprecedented epidemics of coffee rust (Hemileia vastatrix). Identification of natural enemies of coffee rust could aid in developing management strategies or in pinpointing species that could be used for biocontrol. In the present study, we characterized fungal communities associated with coffee rust lesions by single-molecule DNA sequencing of fungal rRNA gene bar codes from leaf discs (Ϸ28 mm 2 ) containing rust lesions and control discs with no rust lesions. The leaf disc communities were hyperdiverse in terms of fungi, with up to 69 operational taxonomic units (putative species) per control disc, and the diversity was only slightly reduced in rust-infected discs, with up to 63 putative species. However, geography had a greater influence on the fungal community than whether the disc was infected by coffee rust. Through comparisons between control and rust-infected leaf discs, as well as taxonomic criteria, we identified 15 putative mycoparasitic fungi. These fungi are concentrated in the fungal family Cordycipitaceae and the order Tremellales. These data emphasize the complexity of diverse fungi of unknown ecological function within a leaf that might influence plant disease epidemics or lead to the development of species for biocontrol of fungal disease. Fungal biodiversity is closely linked to plant biodiversity, because a dominant number of fungal taxa are symbiotic with plants (1, 2). On one end of the symbiosis spectrum are plant pathogens, whose impacts are enormous in agricultural production, dramatically reducing yields or even eliminating production altogether, as well as in natural ecosystems, where they may facilitate plant biodiversity by Janzen-Connell effects, coevolutionary processes, or other mechanisms. At the other end of the spectrum are mutualists of plants, including beneficial mycorrhizae and endophytes that promote plant growth and facilitate stress tolerance (3, 4). Somewhere in the middle are the majority of plant-symbiotic fungi, with copious species detected within and on asymptomatic plant tissues. Most of these fungi have unclear roles with respect to plant health but comprise a massive and ubiquitous proportion of overall fungal biodiversity, especially in the lowland tropics, where every leaf sampled reveals the presence of endophytes by use of culture techniques (5, 6). Although some endophytes may have no direct effect on the host, what is becoming increasingly more appreciated is that endophytes can benefit the host through indirect actions, such as by protection from plant pests and pathogens (7,8).In natural ecosystems, cascading trophic interactions are tied to ecosystem stability and diversity (9). These trophic interactions involve numerous natural enemie...
Parasites and predators can have complex, nonadditive effects on a shared group of victims, which can have important consequences for population dynamics. In particular, parasites can alter host traits that influence predation risk, and predators can have nonconsumptive effects on prey traits which influence susceptibility (i.e., infection intensity and tolerance) to parasites. Here, we examined the combined effects of trematode parasites (Digenea: Echinostomatidae) and odonate (Anax) predators on the survival of larval green frogs (Rana clamitans). First, in a large-scale mesocosm experiment, we manipulated the presence or absence of parasites in combination with the presence of no predator, caged predators, or free predators, and measured survival, traits, and infection. Parasites, caged predators, and free predators decreased survival, and we found a strong negative synergistic effect of parasites in combination with free predators on survival. Importantly, we then examined the potential mechanisms that explain the observed synergistic effect of parasites and predators in a series of follow-up experiments. Results of the follow-up experiments suggest that increased predation susceptibility due to elevated activity levels in the presence of free-swimming parasite infective stages (i.e., an avoidance response) is the most likely mechanism responsible for the observed synergism. These results suggest a potential trade-off in susceptibility to parasites and predators, which can drive nonadditive effects that may have important consequences for natural enemy interactions in natural populations and amphibian conservation.
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