Information needs and priorities for assessing the sensitivity of marine birds to oil spills

Our experience in developing models to predict the potential impacts of oil spills on colonially breeding marine birds has revealed some major gaps in the information available on these systems. We consider the availability of data for a variety of parameters of seabird biology that are required in modelling efforts, and assign provisional priorities to our information needs. In order to develop means of predicting the impacts of oil spills on seabirds, we suggest that colony- or site-specific information on the timing of reproduction and colony occupancy, chick growth rates and body weights, several metabolic parameters, flight speed, and food load size is of relatively low overall priority. Intermediate priority is assigned to the collection of specific data on the dynamics of oil spills, the age and breeding structure of the populations, reproductive success, foraging activity budgets and flight paths, flight costs, and the response of growing chicks to food deprivation. We suggest that studies of seabird biology should give highest priority to obtaining information on population sizes, the probability of adult death upon encountering a spill, age-specific fecundity and survivorship, the time required in foraging trips, the lag time in the response of birds to an oil spill, foraging rate as a function of resource density, and changes in the availability of resources to the birds as a consequence of oil spills.     

Constraints on neon and argon isotopic fractionation in solar wind

To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.     

Scaling of ‘landscapes’ in landscape ecology,or, landscape ecology from a beetle's perspective

Research performed on microlandscapes embodies the essence of landscape ecology by focusing on the ecological consequences of the mosaic structure of different landscape elements. As an illustration, observations and simulations were used to test whether the fractal structure of grassland microlandscapes affected the movement patterns of tenebrionid beeetles in natural environments. The significant tendency of beetles to avoid 1 m² cells with fractal dimensions of 1.85 to 1.89 (indicating the area-filling tendency of bare ground) demonstrated the role of landscape structure as a modifier of beetle movements or diffusion in heterogeneous landscapes. Experiments in microlandscapes may accelerate the development of quantitative conceptual frameworks applicable to landscapes at all scales.     

Acute Mortality,Bacterial Load,and Pathology of Select Lines of Adult Rainbow Trout Challenged with Weissella sp. NC36

Abstract

A challenge for improving disease resistance in fish through genetics is to understand specificity of resistance and whether selection for one pathogen alters the response to unrelated pathogenic microorganisms. Adult Rainbow Trout Oncorhynchus mykiss that had been bred for differential susceptibility to Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD) and designated ARS-Fp-R (resistant), ARS-Fp-S (susceptible), and ARS-Fp-C (control line), as well as a pool of commercial-stock Rainbow Trout, were intraperitoneally challenged with Weissella sp. NC36. Clinical signs, survival, and innate mechanisms affecting disease resistance were monitored over 9 d. Acute disease signs included exophthalmia associated with retrobulbar inflammation and hemorrhage, cerebral hemorrhage, and mild to moderate granulomatous pericarditis. The ARS-Fp-R line did not demonstrate significant survival differences over a 9-d period compared with the ARS-Fp-C and ARS-Fp-S lines (P ≥ 0.09) indicating that during the acute phase of disease, the resistance factors that limit BCWD do not confer cross protection against Weissella sp. NC36. The linear effect of body weight at challenge was statistically significant, as each 10-g increase in body weight increased the hazard of death by 1% (P = 0.02). Bacterial loads on day 3, assessed by splenic and cerebral CFU counts, did not differ between ARS-Fp-R and ARS-Fp-S trout and there was no correlation between CFU counts and body weight. These findings help elucidate the specificity of disease resistance in selectively bred lines and contribute to our understanding of disease caused by Weissella sp., a recently described pathogen found in cultured Rainbow Trout.

Received June 19, 2013; accepted June 23, 2013     

Isolation and characterization of a Mn(II)-oxidizing Bacillus strain from the demosponge Suberites domuncula

In this study we demonstrate that the demosponge Suberites domuncula harbors a Mn(II)-oxidizing bacterium, a Bacillus strain, termed BAC-SubDo-03. Our studies showed that Mn(II) stimulates bacterial growth and induces sporulation. Moreover, we show that these bacteria immobilize manganese on their cell surface. Comparison of the 16S rDNA sequence allowed the grouping of BAC-SubDo-03 to the Mn-precipitating bacteria. Analysis of the spore cell wall revealed that it contains an Mn(II)-oxidizing enzyme. Co-incubation studies of BAC-SubDo-03 with 100 μM MnCl(2) and >1 μM of CuCl(2) showed an increase in their Mn(II)-oxidizing capacity. In order to prove that a multicopper oxidase-like enzyme(s) (MCO) exists in the cell wall of the S. domuncula-associated BAC-SubDo-03 Bacillus strain, the gene encoding this enzyme was cloned (mnxG-SubDo-03). Sequence alignment of the deduced MCO protein (MnxG-SubDo-03) revealed that the sponge bacterium clusters together with known Mn(II)-oxidizing bacteria. The expression of the mnxG-SubDo-03 gene is under strong control of extracellular Mn(II). Based on these findings, we assume that BAC-SubDo-03 might serve as a Mn reserve in the sponge providing the animal with the capacity to detoxify Mn in the environment. Applying the in vitro primmorph cell culture system we could demonstrate that sponge cells, that were co-incubated with BAC-SubDo-03 in the presence of Mn(II), show an increased proliferation potential.     

Repeating deep earthquakes: evidence for fault reactivation at great depth

We have identified three groups of deep earthquakes showing nearly identical waveforms in the Tonga slab. Relocation with a cross-correlation method shows that each cluster is composed of 10 to 30 earthquakes along a plane 10 to 30 kilometers in length. Some of the earthquakes are colocated, demonstrating repeated rupture of the same fault, and one pair of events shows identical rupture complexity, suggesting that the temporal and spatial rupture pattern was repeated. Recurrence intervals show an inverse time distribution, indicating a strong temporal control over fault reactivation. Runaway thermal shear instabilities may explain temporally clustered earthquakes with similar waveforms located along slip zones weakened by shear heating. Earthquake doublets that occur within a few hours are consistent with events recurring before the thermal energy of the initial rupture can diffuse away.     

Movements of cactus bugs: Patch transfers,matrix resistance,and edge permeability

Individual movement is a key process affecting the distribution of animals in heterogeneous landscapes. For specialist species in patchy habitat, a central issue is how dispersal distances are related to landscape structure. We compared dispersal distances for cactus bugs (Chelinidea vittiger) on two naturally fragmented landscapes (≤ 4% suitable habitat) with different matrix structures (i.e., vegetation height of nonsuitable habitat between suitable patches). Using mark-release-recapture studies, we determined that most transfers between cactus patches occurred during the mating season. Dispersal distances were reduced by > 50% on the landscape that had reduced structural connectivity due to relatively high matrix structure and low patch density. An experiment with detailed movement pathways demonstrated that greater matrix structure decreased mean step lengths, reduced directionality, and thus decreased net displacement by > 60%. However, habitat edges between two matrix elements that differed substantially in resistance to movement were completely permeable. Therefore, the difference in distributions of dispersal distances between the two landscapes mainly reflected the average resistance of matrix habitat and not the level of matrix heterogeneity per se. Our study highlights the merits of combining estimates of dispersal distances with insights on mechanisms from detailed movement pathways, and emphasizes the difficulty of treating dispersal distances of species as fixed traits independent of landscape structure.