Community-Based Control of the Brown Dog Tick in a Region with High Rates of Rocky Mountain Spotted Fever, 2012–2013

Rocky Mountain spotted fever (RMSF) transmitted by the brown dog tick (Rhipicephalus sanguineus sensu lato) has emerged as a significant public health risk on American Indian reservations in eastern Arizona. During 2003–2012, more than 250 RMSF cases and 19 deaths were documented among Arizona''s American Indian population. The high case fatality rate makes community-level interventions aimed at rapid and sustained reduction of ticks urgent. Beginning in 2012, a two year pilot integrated tick prevention campaign called the RMSF Rodeo was launched in a ∼600-home tribal community with high rates of RMSF. During year one, long-acting tick collars were placed on all dogs in the community, environmental acaricides were applied to yards monthly, and animal care practices such as spay and neuter and proper tethering procedures were encouraged. Tick levels, indicated by visible inspection of dogs, tick traps and homeowner reports were used to monitor tick presence and evaluate the efficacy of interventions throughout the project. By the end of year one, <1% of dogs in the RMSF Rodeo community had visible tick infestations five months after the project was started, compared to 64% of dogs in Non-Rodeo communities, and environmental tick levels were reduced below detectable levels. The second year of the project focused on use of the long-acting collar alone and achieved sustained tick control with fewer than 3% of dogs in the RMSF Rodeo community with visible tick infestations by the end of the second year. Homeowner reports of tick activity in the domestic and peridomestic setting showed similar decreases in tick activity compared to the non-project communities. Expansion of this successful project to other areas with Rhipicephalus-transmitted RMSF has the potential to reduce brown dog tick infestations and save human lives.     

Photodynamic alteration of cornea endothelium: Relation to bicarbonate fluxes and oxygen concentration

Corneas were mounted in flux chambers and endothelial bicarbonate fluxes were determined following sensitization of endothelial cells with 5 · 10^?6 M rose bengal and exposure to light. Corneas exposed to light demonstrated an increased passive bicarbonate flux compared to corneas not photosensitized. Active bicarbonate flux was reduced after 5 min of light exposure, but not after 1 min of light exposure. The increase in passive bicarbonate flux was prevented by the addition of 200 μg/ml catalase to the bathing solution; however, catalase had no effect on the photodynamic alteration of active flux. Neither 10 mM ascorbic acid nor 1.012 g/l glutathione prevented the photodynamically induced increase in passive flux. Perfusion of corneas with 5 · 10^?6 M rose bengal dissolved in a sucrose-substituted Krebs-Ringer bicarbonate solution with a $\text{p}{}_{\mathrm{<mtext>o</mtext>}}{}_2$ of $\text{124 ± 4.0}\text{mmHg}$ and exposed to light swelled at rates more rapid than corneas treated in a similar fashion but perfused with a solution with a $\text{P}{}_{\mathrm{<mtext>o</mtext>}}{}_2$ of $\text{20 ± 4.6}\text{mmHg}$. This study demonstrates that photodynamically induced corneal endothelial cell alteration results in increased passive bicarbonate flux, a time-dependent decrease in active bicarbonate flux, is oxygen dependent, and is at least in part secondary to H₂O₂ produced by the dismutation reaction of the superoxide free radical.     

Influence of the Thin Drift Algal Mats on the Distribution of Macrozoobenthos in Kõiguste Bay, NE Baltic Sea

Macrozoobenthic communities within and outside of the drift algal mats were compared in Kõiguste Bay, NE Baltic Sea. The patches of the drift algae were on average 0.5–1 km wide in diameter covering about 25% of the total bottom area of the bay. Thickness of the mat did not exceed 6 cm. The biomass of the mat varied between 35 and 1391 g dw m^?2. The drift algal mats had no clear negative effect on macrozoobenthos except for a few infaunal species. The drift algae favoured several detrivorous, herbivorous and carnivorous species. Among the studied variables, the thickness of algal mat and oxygen concentration at near-bottom layer explained the best the structure of macrozoobenthos. Total number of invertebrate species increased curvilinearly with the thickness of algal mat having the peak value at 3–5 cm thick algal mat. To conclude, moderate drift algal mats increased habitat complexity and, thus, the diversity of benthic faunal assemblages in otherwise poorly vegetated coastal areas.     

Establishing Functional Relationships between Abiotic Environment,Macrophyte Coverage,Resource Gradients and the Distribution of Mytilus trossulus in a Brackish Non-Tidal Environment

Benthic suspension feeding mussels are an important functional guild in coastal and estuarine ecosystems. To date we lack information on how various environmental gradients and biotic interactions separately and interactively shape the distribution patterns of mussels in non-tidal environments. Opposing to tidal environments, mussels inhabit solely subtidal zone in non-tidal waterbodies and, thereby, driving factors for mussel populations are expected to differ from the tidal areas. In the present study, we used the boosted regression tree modelling (BRT), an ensemble method for statistical techniques and machine learning, in order to explain the distribution and biomass of the suspension feeding mussel Mytilus trossulus in the non-tidal Baltic Sea. BRT models suggested that (1) distribution patterns of M. trossulus are largely driven by separate effects of direct environmental gradients and partly by interactive effects of resource gradients with direct environmental gradients. (2) Within its suitable habitat range, however, resource gradients had an important role in shaping the biomass distribution of M. trossulus. (3) Contrary to tidal areas, mussels were not competitively superior over macrophytes with patterns indicating either facilitative interactions between mussels and macrophytes or co-variance due to common stressor. To conclude, direct environmental gradients seem to define the distribution pattern of M. trossulus, and within the favourable distribution range, resource gradients in interaction with direct environmental gradients are expected to set the biomass level of mussels.     

Is salinity an obstacle for biological invasions?

Invasions of freshwater habitats by marine and brackish species have become more frequent in recent years with many of those species originating from the Ponto‐Caspian region. Populations of Ponto‐Caspian species have successfully established in the North and Baltic Seas and their adjoining rivers, as well as in the Great Lakes–St. Lawrence River region. To determine if Ponto‐Caspian taxa more readily acclimatize to and colonize diverse salinity habitats than taxa from other regions, we conducted laboratory experiments on 22 populations of eight gammarid species native to the Ponto‐Caspian, Northern European and Great Lakes–St. Lawrence River regions. In addition, we conducted a literature search to survey salinity ranges of these species worldwide. Finally, to explore evolutionary relationships among examined species and their populations, we sequenced the mitochondrial cytochrome c oxidase subunit I gene (COI) from individuals used for our experiments. Our study revealed that all tested populations tolerate wide ranges of salinity, however, different patterns arose among species from different regions. Ponto‐Caspian taxa showed lower mortality in fresh water, while Northern European taxa showed lower mortality in fully marine conditions. Genetic analyses showed evolutionary divergence among species from different regions. Due to the geological history of the two regions, as well as high tolerance of Ponto‐Caspian species to fresh water, whereas Northern European species are more tolerant of fully marine conditions, we suggest that species originating from the Ponto‐Caspian and Northern European regions may be adapted to freshwater and marine environments, respectively. Consequently, the perception that Ponto‐Caspian species are more successful colonizers might be biased by the fact that areas with highest introduction frequency of NIS (i.e., shipping ports) are environmentally variable habitats which often include freshwater conditions that cannot be tolerated by euryhaline taxa of marine origin.     

Ecological consequences of biological invasions: three invertebrate case studies in the north-eastern Baltic Sea

Population dynamics and ecological impacts of the cirriped Balanus improvisus, the polychaete Marenzelleria neglecta and the cladoceran Cercopagis pengoi were investigated in the north-eastern Baltic Sea. After an increase during the first decade of invasion, the density of M. neglecta and C. pengoi declined afterwards. The studied abiotic environmental variables did not explain the interannual variability in the seasonal cycles of M. neglecta and C. pengoi indicating that the species are at their initial phase of invasion. The population dynamics of B. improvisus was best described by water temperature. B. improvisus promoted the growth of the green alga Enteromorpha intestinalis. M. neglecta enhanced the content of sediment chlorophyll a and reduced growth and survival of the polychaete Hediste diversicolor and growth of the amphipod Monoporeia affinis. Concurrent with the invasion of C. pengoi the abundance of small-sized cladocerans declined, especially above the thermocline. C. pengoi had become an important food for nine-spined stickleback, bleak, herring and smelt.