Refining Nitrogen and Phosphorus Fertilization Strategies for Controlling the Toxigenic Alga Prymnesium parvum1

Kurten, Gerald L., Aaron Barkoh, Drew C. Begley, and Loraine T. Fries, 2010. Refining Nitrogen and Phosphorus Fertilization Strategies for Controlling the Toxigenic Alga Prymnesium parvum. Journal of the American Water Resources Association (JAWRA) 46(1):170-186. DOI: 10.1111/j.1752-1688.2009.00401.x Abstract: Previous studies have shown that three times weekly applications of phosphorus (30 μg P/l) and nitrogen (300 μg N/l) were effective at reducing the density and toxicity of the alga Prymnesium parvum in limnocorrals simulating a 40-day moronid (e.g., striped bass, Morone saxatilis, and palmetto bass, M. saxatilis ×Morone chrysops) fingerling culture period. However, this fertilization regime produced high pH and unionized ammonia-N concentrations that are detrimental to the survival of moronid fry and fingerlings. In two follow-up experiments we changed the source of N from ammonia to nitrate, reduced fertilization rates, and examined the effect of N-only or P-only fertilization. In the first experiment P fertilization rates were reduced by one-half to 15 μg P/l and NO₃-N was substituted for NH₃-N at the previously used rate of 300 μg N/l. In the second experiment, N fertilization rates were reduced to 150 μg N/l and the frequency of fertilization was determined by pH and P. parvum responses. Nitrate appeared to be as effective as ammonia as a source of N and when used in combination with P reduced P. parvum cell density and ichthyotoxicity. However, reduced N and P application rates and lower pond water temperatures during the study appeared to have decreased the speed at which fertilization produced these effects. While lower fertilization rates reduced algal productivity, high pH remained a concern for fish culture although pH was reduced to levels that might be acceptable with careful management of fish culture activities. Neither N-only nor P-only fertilization had a measurable effect on algal productivity or eliminated P. parvum and its toxicity. Furthermore, P-only fertilization may have increased P. parvum density and toxicity. For controlling P. parvum density and ichthyotoxicity we recommend a fertilization rate of 212 μg NO₃-N/l plus 30 μg PO₄-P/l applied three times weekly for aquaculture ponds where high pH is not a concern. Where high pH is a concern we recommend a fertilization rate of 117 μg NO₃-N/l plus 16 μg PO₄-P/l applied three times weekly with careful attention to afternoon pond pH.     

Effects of low dissolved oxygen on organisms used in freshwater sediment toxicity tests

Minimum dissolved oxygen requirements are part of standard guidelines for toxicity testing of freshwater sediments with several benthic invertebrates, but the data underlying these requirements are somewhat sparse. We exposed three common test organisms to ranges of dissolved oxygen concentrations to determine their responses in 10-d exposures, relative to published guidelines for sediment toxicity tests. The oligochaete, Lumbriculus variegatus, showed 100% survival in all exposures down to the lowest concentration tested, 0.7 mg O(2)l(-1). Midge (Chironomus dilutus) larva showed a more pronounced response; while survival was less than 90% only below 1.0mg O(2)l(-1), the biomass endpoint showed EC(50), EC(20), and EC(10) values of 1.00 (0.91-1.10), 1.41 (1.16-1.71), and 1.67 (1.25-2.24) mg O(2)l(-1). The amphipod, Hyalella azteca, showed no adverse effects at concentrations as low as 2.12 mg O(2)l(-1). The combination of these data with other literature data suggest that DO minima in current North American 10-d sediment test guidelines are reasonable.     

Consumer product-related eye injury in the United States, 1998-2002

PROBLEM: Eye injury is currently a leading cause of visual impairment and monocular blindness in the United States. Information regarding consumer products associated with eye injuries can have important implications for the prevention of these injuries. METHODS: The National Electronic Injury Surveillance System (NEISS) was used to describe the types of consumer products associated with emergency department treated eye injuries in the United States from 1998 through 2002. RESULTS: The leading product type associated with eye injuries was welding equipment followed by household cleaners, basketball equipment, workshop equipment, and adhesives. Eye injuries attributed to hardware, tools, construction, sports, toys, and lawn equipment were more common among males. In females, eye injuries attributable to chemicals, housewares, storage and organization, and bed and bath items were more common. Differences were also apparent across the age spectrum. CONCLUSION: This study identified specific products and categories of products frequently associated with eye injury and prevention initiatives should focus on these items. IMPACT ON INDUSTRY: This study has identified consumer products associated with eye injuries requiring medical treatment in the United States. Manufacturers of these products could be encouraged to add or strengthen safety messages regarding the potential for eye injury.     

Simulation tools to support bathing water quality management: Escherichia coli bacteria in a Baltic lagoon

Insufficient hygienic water quality and bathing prohibitions are still a serious problem in the Szczecin Lagoon (southern Baltic). In our study we focus on the southern lagoon coast and analyse the causes and consequences of high Escherichia coli bacteria concentrations. For this purpose we carry out laboratory experiments on the behaviour of E.coli in the lagoon, a literature review and apply a three-dimensional flow model together with a Lagrangian particle tracking routine. Three major E.coli sources, the Uecker river, the wetlands with cattle as well as sea gulls with bathing and fisheries were allocated, quantified and compiled into an emission scenario. This serves as input for transport simulations under different wind conditions and for the development of a spatial contamination map. Reasons for high E.coli concentrations in the lagoon are a permanent supply from different sources and the special environmental situation in the lagoon. The availability of organic matter, either in form of reed stems or as muddy sediments, has a positive effect on bacteria survival. Very important, too, are the prevailing wind and flow conditions, which cause water and organism transport in narrow ribbons along the coastline and promote near-shore accumulations. Even in our shallow lagoon, the application of a 3D-model is beneficial. Heavy rains are, very likely, responsible for the outstanding high total-coliform concentrations of 11,000?cfu/100?ml on August 21, 2006. The model system proved to be a valuable tool for spatial analysis and is suitable to support the development of bathing water profiles according to the EU Bathing Water Directive (2006/7/EC).     

Individual specific contact calls of pallid bats (<Emphasis Type="Italic">Antrozous pallidus</Emphasis>) attract conspecifics at roosting sites

Contact calls are utilized by several bird and mammal species to maintain group cohesion and coordinate group movement. From a signal design perspective, contact calls typically exhibit acoustic features that make them easily localizable and encode information about individual or group identity. Pallid bats (Antrozous pallidus) are unusual among vespertilionids in that they often emit a loud, partially audible frequency-modulated social call several times in rapid succession while in flight. This call appears to function as a contact call in that it is frequently given when bats return from foraging and perform circular flights before entering a crevice roost. However, the degree to which pallid bats respond to the calls of conspecifics and what information is provided in the call is unknown. Thus, the goal of this study was to investigate pallid bat calling behavior to determine if calls attract roostmates or elicit responses from them and provide sufficient information for individual recognition. In playback studies, we found that contact calls, elicit calls, and approaches and that free-flying bats respond more to familiar than unfamiliar calls. In addition, analysis of frequency and temporal measurements of calls collected from multiple sites and spectral cross correlation analysis of calls recorded from the same radio-tagged bats on multiple evenings revealed that the frequency pattern of contact calls is highly repeatable over time within individuals but exhibits significant differences among individuals. Thus, contact call structure appears to be unique to individuals and stable through time, which makes these calls well-suited for roostmate recognition.     

Social waves in giant honeybees (Apis dorsata) elicit nest vibrations

Giant honeybees (Apis dorsata) nest in the open and have developed a wide array of strategies for colony defence, including the Mexican wave-like shimmering behaviour. In this collective response, the colony members perform upward flipping of their abdomens in coordinated cascades across the nest surface. The time–space properties of these emergent waves are response patterns which have become of adaptive significance for repelling enemies in the visual domain. We report for the first time that the mechanical impulse patterns provoked by these social waves and measured by laser Doppler vibrometry generate vibrations at the central comb of the nest at the basic (=‘natural’) frequency of 2.156?±?0.042 Hz which is more than double the average repetition rate of the driving shimmering waves. Analysis of the Fourier spectra of the comb vibrations under quiescence and arousal conditions provoked by mass flight activity and shimmering waves gives rise to the proposal of two possible models for the compound physical system of the bee nest: According to the elastic oscillatory plate model, the comb vibrations deliver supra-threshold cues preferentially to those colony members positioned close to the comb. The mechanical pendulum model predicts that the comb vibrations are sensed by the members of the bee curtain in general, enabling mechanoreceptive signalling across the nest, also through the comb itself. The findings show that weak and stochastic forces, such as general quiescence or diffuse mass flight activity, cause a harmonic frequency spectrum of the comb, driving the comb as an elastic plate. However, shimmering waves provide sufficiently strong forces to move the nest as a mechanical pendulum. This vibratory behaviour may support the colony-intrinsic information hypothesis herein that the mechanical vibrations of the comb provoked by shimmering do have the potential to facilitate immediate communication of the momentary defensive state of the honeybee nest to the majority of its members.     

All-offspring dispersal in a tropical mammal with resource defense polygyny

In polygynous mammals, males are usually responsible for gene flow while females are predominantly philopatric. However, there is evidence that in a few mammalian species female offspring may disperse to avoid breeding with their father when male tenure exceeds female age at maturity. We investigated offspring dispersal and local population structure in the Neotropical bat Lophostoma silvicolum. The mating system of this species is resource defense polygyny, with the resource being active termite nests, excavated by single males, which are then joined by females. We combined field observations of 14 harems during 3 years and data about the genetic structure within and between these groups, calculated with one mitochondrial locus and nine nuclear microsatellite loci. The results show that both male and female offspring disperse before maturity. In addition, we estimated life span of excavated termite nests and the duration they were occupied by the same male. Our findings suggest that long male tenure of up to 30 months is indeed a likely cause for the observed dispersal by female offspring that can reach maturity at a low age of 6 months. We suggest that dispersal by offspring of both sexes may occur quite frequently in polygynous tropical bats and thus generally may be more common in mammals than previously assumed.