Mating and its effect on acoustic signalling behaviour in a primitive orthopteran,Cyphoderris strepitans (Haglidae): the cost of feeding females

Summary Males of the primitive orthopteran, Cyphoderris strepitans, provide their mates with two types of nuptial food gift during mating: 1) females feed while coupled on the fleshy metathoracic wings of the male and the resultant flow of haemolymph and 2) the spermatophore transferred by the male includes a gelatinous spermatophylax which the female eats after mating. During the peak breeding interval, virgin males secure significantly more matings than their numbers relative to non-virgin males would predict. We tested the hypothesis that non-virgin males, having lost a substantial portion of available energy through previous investment in females, call significantly less than virgin males. Reduced calling should result in the attraction of fewer females and/or a greater risk of intrusion from competing males and consequently, a lowered mating success. Calling activity of male C. strepitans of varying mating status was monitored with a sound activated relay apparatus for two consecutive nights following their capture. Males were of three experimental groups, virgin, freshly wounded males (mated on the same night of capture), and old-wound males (mated at least one night prior to capture). Our cata showed a significant short-term reduction in signalling activity as a consequence of mating. Whereas there was no difference in the time spent calling by virgins on the first and second nights following capture, freshly wounded and oldwound males called significantly less on the first night than on the second. Furthermore, the proportion of males calling on both nights was significantly greater for the virgin and old-wound groups than for freshly wounded males. When the duration over which males called on the first night was compared with that of the second, virgin males showed no difference whereas old-wound males called for significantly shorter intervals on the first night. These results indicate that the cost of a large nutrient investment in females lowers the energy level in males below the threshold required for a prolonged signalling period. After a refractory interval during which males feed and replenish their energy reserves, calling levels equivalent to those which occur prior to mating are regained. Active female choice may also contribute to the reduced mating success of non-virgins, but this possibility remains untested.     

Female-coerced monogamy in burying beetles

The reproductive interests of the sexes often do not coincide, and this fundamental conflict is believed to underlie a variety of sex-specific behavioral adaptations. Sexual conflict in burying beetles arises when a male and female secure a carcass that can support more offspring than a single female can produce. In such a situation, any male attracting a second female sires more surviving offspring than he would by remaining monogamous, whereas the female's reproductive success decreases if a rival female is attracted to the carcass. Monogamously paired males on large carcasses do in fact attempt to attract additional females by means of pheromone emission, whereas males on small carcasses do not. Females physically interfere with male polygynous signaling using various behavioral tactics. We demonstrate that such interference leads to a significant decrease in the amount of time that males spend signaling, according females a means by which to impose monogamy on their mates.     

Anthropogenic Correlates of Species Richness in Southeastern Ontario Wetlands

We examined the relationship between the richness of four different wetland taxa (birds, mammals, herptiles, and plants) in 30 southeastern Ontario, Canada wetlands and two anthropogenic factors: road construction and forest removal/conversion on adjacent lands. Data were obtained from two sources: road densities and forest cover from 1:50,000 Government of Canada topographic maps and species lists and wetland areas from Ontario Ministry of Natural Resources wetland evaluation reports. Multiple regression analysis was used to model the relationships between species richness and wetland area, road density, and forest cover. Our results show a strong positive relationship between wetland area and species richness for all taxa. The species richness of all taxa except mammals was negatively correlated with the density of paved roads on lands up to 2 km from the wetland. Furthermore, both herptile and mammal species richness showed a strong positive correlation with the proportion of forest cover on lands within 2 km. These results provide evidence that at the landscape level, road construction and forest removal on adjacent lands pose significant risks to wetland biodiversity. Furthermore, they suggest that most existing wetland policies, which focus almost exclusively on activities within the wetland itself and/or a narrow buffer zone around the wetland perimeter, are unlikely to provide adequate protection for wetland biodiversity.     

Effects of Habitat Area on the Distribution of Grassland Birds in Maine

We used multiple and logistic regression analysis to study the breeding-area requirements of 10 species of grassland and early-successional birds at 90 grassland-barren sites in Maine. The incidence of six of the species was clearly sensitive to the area of grassland. Upland Sandpipers, the species with the largest area requirements, were infrequent at sites of less than 50 ha and reached 50% incidence at those of about 200 ha. Grasshopper Sparrows reached 50% incidence at about 100 ha, Vesper Sparrows at about 20 ha, and Savannah Sparrows at about 10 ha. Incidence for three edge species, Brown Thrasher, Common Yellowthroat, and Song Sparrow, was negatively correlated with open area, and incidence for Field Sparrows was not strongly influenced by grassland size. These results indicate that grasslands need to be approximately 200 ha in area if they are to be likely to support a diverse grass land bird fauna. However, large grasslands or grassland-barrens are rare; random samples indicated that in Maine only 1% of hayfields and only 8% of grassland-barrens were more than 64 ha in area. Conservation efforts seeking to protect habitat for rare grassland birds need to consider sites of at least 100 ha—and preferably 200 ha—in size, and these are notably rare in Maine and probably throughout New England and eastern North America. Airports provide some of the last extensive patches of grassland habitat in the northeast. To maintain viable populations of area-sensitive grassland birds, management of these sites for nesting birds will become increasingly important.     

Trends in spatial and temporal levels of persistent organic pollutants in Lake Erie sediments

A Lake Erie sediment survey was conducted in 1997 to characterize spatial trends in contamination, and for comparison with a 1971 survey to assess any changes in environmental quality since the advent of measures to reduce contaminant sources. Contaminant data for some contaminant classes in 1971 was based on analysis of frozen archived samples, thereby allowing a direct comparison between surficial sediment contamination in 1971 and 1997 based on modern analytical methods. Lake-wide contaminant concentrations of polychlorinated biphenyls (PCBs) and organochlorine compounds including hexachlorobenzene and the DDT compounds in 1997 were substantially lower, compared to levels in samples collected in 1971. Lake-wide average sediment PCB levels were found to have decreased roughly 70% from 136 ng/g in 1971 to 43 ng/g in 1997. Similarly, reductions in other compound classes ranged from 40% to 80%. In 1997, some individual contaminants classes including PCBs exhibited a spatial trend toward increasing sediment contamination from the eastern basin to the western basin, and from the north-central basin to the south-central basin. Levels of organic contaminants in sediments in some areas of Lake Erie still exceeded the strictest Canadian Federal and Ontario Provincial guidelines. However, exceedances of guidelines describing contaminated environments in 1997 were predominantly restricted to the western basin and near-shore sites in the southern part of the central basin.     

Effect of NOx control processes on mercury speciation in utility flue gas

The speciation of Hg in coal-fired flue gas can be important in determining the ultimate Hg emissions as well as potential control options for the utility. The effects of NOx control processes, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR), on Hg speciation are not well understood but may impact emissions of Hg. EPRI has investigated the reactions of Hg in flue gas at conditions expected for some NOx control processes. This paper describes the methodology used to investigate these reactions in actual flue gas at several power plants. Results have indicated that some commercial SCR catalysts are capable of oxidizing elemental Hg in flue gas obtained from the inlets of SCR or air heater units. Results are affected by various flue gas and operating parameters. The effect of flue gas composition, including the presence of NH3, has been evaluated. The influence of NH3 on fly ash Hg reactions also is being investigated.     

Spatial and temporal distribution of butyltin compounds in a Northern Chesapeake Bay Marina and river system

This study was designed to: determine dibutyltin (DBT), tributyltin (TBT) and tetrabutyltin (TTBT) bi-weekly for a four month period (June-September 1986) in the Port Annapolis Marina, Mears Marina, Back Creek and Severn River area of Northern Chesapeake Bay; measure DBT, TBT and TTBT for five successive days (Thursday-Monday) to determine possible daily effects (weekday versus weekend) and determine DBT, TBT and TTBT every two hours for one full tidal cycle in the study area. Maximum concentrations of TBT were reported at both Port Annapolis Marina (1801 ng L^–1) and Mears Marina (1171 ng L^–1) during early June followed by significant reductions in TBT during late summer and early fall. All 4 Back Creek Stations also had highest concentrations of TBT in early June; significant reductions occurred during the next three months. The highest concentration of TBT reported in the Severn River (48 ng L^–1) occurred in September. The lowest TBT value (5 ng L^-1) at this station occurred in June. TTBT was not detected in any of the samples. The day of week sampled (Thursday-Monday) during the daily experiments was not found to significantly affect TBT concentrations. TBT evaluations every two hours during the tidal cycle demonstrated that values peaked at 1400 and 1600 hr time intervals. Peak concentrations of TBT occurred during a rising tide. The possible consequence of the measured TBT concentrations for aquatic biota are discussed.