Developmental Instability in Fragmented Populations of Prairie Phlox: A Cautionary Tale

Abstract: Considerable attention has recently been focused on using levels of developmental instability among members of a population to detect environmental or genetic stresses on animals or plants. It is not yet clear, however, that high developmental instability in a sample of individuals always indicates environmental stress or poor genetic quality. We studied 13 fragmented populations of prairie phlox (   Phlox pilosa L.) to test the hypothesis that developmental instability should decrease with increasing population size—as expected if small populations suffer genetic problems associated with inbreeding or are exposed to more environmental stress than larger populations. We used two different measures of developmental instability, each calculated for two different traits: radial asymmetry of flowers (for petal width and petal length) and modular fluctuating asymmetry of leaves (  for leaf widths at two points along the leaf  ). There were weak but significant correlations among individuals for four of six pairwise combinations of these measures. Surprisingly, three of our four measures of developmental instability showed strong population size effects that were opposite to those expected: developmental instability increased with population size. We conclude that measures of developmental instability cannot be applied uncritically for biomonitoring without considerable knowledge of developmental mechanisms, natural history, and population biology of the species in question.     

Predation of a sand-dwelling mysid crustacean Gastrosaccus sanctus by plover birds (Charadriidae)

The plovers Charadrius hiaticula and C. alexandrinus feed on the mysid shrimp Gastrosaccus sanctus (van Beneden, 1861). They hunt at random along the sandy seashore, on the sites of the densest mysid population, regardless of the size of the mysids.     

A Bayesian approach for understanding the role of ship speed in whale-ship encounters

Mandatory or voluntary reductions in ship speed are a common management strategy for reducing deleterious encounters between large ships and large whales. This has produced strong resistance from shipping and marine transportation entities, in part because very few studies have empirically demonstrated whether or to what degree ship speed influences ship-whale encounters. Here we present the results of four years of humpback whale sightings made by observers aboard cruise ships in Alaska, representing 380 cruises and 891 ship-whale encounters. Encounters occurred at distances from 21 m to 1000 m (x = 567 m) with 61 encounters (7%) occurring between 200 m and 100 m, and 19 encounters (2%) within 100 m. Encounters were spatially aggregated and highly variable across all ship speeds. Nevertheless a Bayesian change-point model found that the relationship between whale distance and ship speed changed at 11.8 knots (6.1 m/s) with whales encountering ships, on average, 114 m closer when ship speeds were above 11.8 knots. Binning encounter distances by 1-knot speed increments revealed a clear decrease in encounter distance with increasing ship speed over the range of 7-17 knots (3.6-8.7 m/s). Our results are the first to demonstrate that speed influences the encounter distance between large ships and large whales. Assuming that the closer ships come to whales the more likely they are to be struck, our results suggest that reduced ship speed may be an effective management action in reducing the probability of a collision.     

A simulation model to evaluate the impacts of invasive earthworms on soil carbon dynamics

Recent studies have reported that earthworm invasions alter native communities and impact nutrient cycling in terrestrial ecosystems. We developed a simulation model to evaluate the potential impacts of earthworm invasions on carbon dynamics, taking into consideration earthworm feeding strategies and priming effects on the microorganisms through their casting activities. Responses of carbon stocks (forest litter, soil organic matter, microbial biomass and earthworm populations) and carbon fluxes (litter decomposition, earthworm consumption, and microbial respiration) were used to evaluate an earthworm invasion of a forest ecosystem. Data from a northern temperate forest (Arnot Forest, New York) were adapted for model calibration and evaluation. Simulation results suggest that the impact and outcome of earthworm invasions are affected by pre-invasion resource availability (litter and soil organic matter), invasive earthworm assemblages (particularly feeding strategy), and invasion history (associated with earthworm population dynamics). The abovementioned factors may also determine invasion progress of earthworm species. The accuracy of the model could be improved by the addition of environmental modules (e.g., soil water regimes), precise parameters accounting for individual species attributes under different environmental conditions (e.g. utilization ability of different types of food resources), as well as earthworm population dynamics (size and structure) and interactions with predators and other invasive/indigenous species during the invasion progress. Such an earthworm invasion model could provide valuable evaluation of the complicated responses of carbon dynamics to earthworm invasions in a range of forest ecosystems, particularly under global change scenarios.     

Amorphous oxides of manganese as new sorbents of strontium ions

Samples with the best adsorption properties are selected as a result of investigations conducted on synthesis of manganese-dioxide-based materials and study of their physicochemical properties. Materials were selected on the basis of their low cost and the simplicity of their production technology. In the laboratory the synthesis and analyses of materials was carried out for selected samples. The sorption of a series of elements is studied for a more detailed investigation of materials obtained. The results obtained will promote the synthesis of materials with improved adsorption properties with the aim of their application for purification of water from strontium. It is shown that the most promising way for amendment of manganese oxide is modification of this material using acid-resistant oxides. These oxides are also less expensive than existing sorbents for strontium.     

Pesticides and Nitrate in Groundwater and Rainwater in the Province of Limburg in The Netherlands

The purpose of this study was to investigate the occurrence ofhigh levels of pesticides in groundwater and rainwater in TheProvince of Limburg in The Netherlands. In groundwater samplesin particular the presence of triazines – atrazine, simazine and propazine – was observed; besides these pesticides, dieldrin has also been observed. Atrazine and simazine were found to exceed the groundwater standard of 100 ng L^-1. In the rainwater samples, the presence of 13 of 23 different analyzed pesticides was observed. A number of pesticides werefound in high concentrations; e.g. atrazine (>200 ng L^-1). Two pesticides detected in rainwater (+-HCH and atrazine) were found to exceed the groundwater standard. Seven pesticides in rainwater were found to exceed the target value and three pesticides the maximum tolerable risk value (DDT, heptachlor and heptachlorepoxide A), which are used as ecotoxicological standards in The Netherlands.Nitrate in 15 of 16 analyzed natural springs was found toexceed the guideline value for nitrate in drinking waterof 50 mg L^-1, up to levels of about 200 mg L^-1. Nitrate concentrations in rainwater samples were observed up to 4.5 mg L^-1. A risk analysis of exposure to high pesticide levels in groundwater or rainwater has been performed using the model HESP. For atrazine levels due todeposition of rainwater in two different locations, exceedance of the T.D.I. level of 0.5 g kg^-1 day^-1 based on WHO criteria was observed for children using both an urban and a rural scenario and use of groundwater as drinking water.     

Photocatalytic detoxification of cyanide and metal cyano-species from precious-metal mill effluents

Photochemically-induced detoxification of various cyanide species from a selected precious-metal mills tailings was investigated in detail. The studies were conducted in the presence or absence of a titanium (IV) oxide semiconductor photocatalyst utilizing simulated sunlight as the irradiation source. It was established that the cyanide ion (both free and complexed) was photocatalytically oxidized to nitrate via cyanate and nitrite. In addition iron, copper, zinc, mercury and arsenic were stabilized as precipitates. The results obtained may have ramifications for the possible use of solar energy for the efficient treatment of large quantities of precious-metal mill-tailing wastes that contain various cyano-species.     

Amorphous oxides of manganese as new sorbents of strontium ions

Samples with the best adsorption properties are selected as a result of investigations conducted on synthesis of manganese-dioxide-based materials and study of their physicochemical properties. Materials were selected on the basis of their low cost and the simplicity of their production technology. In the laboratory the synthesis and analyses of materials was carried out for selected samples. The sorption of a series of elements is studied for a more detailed investigation of materials obtained. The results obtained will promote the synthesis of materials with improved adsorption properties with the aim of their application for purification of water from strontium. It is shown that the most promising way for amendment of manganese oxide is modification of this material using acid-resistant oxides. These oxides are also less expensive than existing sorbents for strontium.     

Population Size and Reproduction in Phlox pilosa

Abstract: We analyzed the relationships between population size and reproductive characteristics in the perennial prairie forb Phlox pilosa , an obligate outcrossing butterfly-pollinated species. We examined 27 populations ranging in size from 9 to over 75,000 flowering ramets in two regions of the state of Iowa (eastcentral and northwest) in 1993 and 1994. We collected flowers from each population and scored them for pollen arrival to stigmas and number of pollen tubes. We collected fruiting ramets from each population at the end of the Phlox growing season and scored them for height, biomass, and reproductive variables, including the number of flowers initiated and opened and the number of capsules initiated and matured. In both years, population size was significantly correlated with the number of capsules matured per ramet. Differences between populations in capsule production were set primarily at the pollination stage. In 1993, pollen arrival to stigmas was significantly lower than in 1994 and was correlated with population size in eastcentral Iowa populations, indicating that lower reproduction in small populations that year was at least partially due to inadequate amounts of pollen being moved. In 1993, weather conditions likely depressed pollinator activity, but absolute capsule formation was high because of high flower production per ramet and high population densities. In 1994, when pollen arrival to stigmas was relatively high and unrelated to population size, outcross pollen movement was greater in larger populations. Increased efficacy of outcross pollen movement in 1994 may have resulted from lower flower production and less dense populations forcing greater pollinator movement between ramets or from variation between years in fine-scale spatial genetic substructuring of populations. Our results indicate that the viability of Phlox pilosa can be best ensured by protecting and creating populations of at least 1000–2000 flowering ramets.