Variation in growth rate and reproductive output in British populations of the dorid nudibranch Adalaria proxima: consequences of restricted larval dispersal?

 Growth and reproduction were compared among six geographically and genetically distinct intertidal populations of the annual, semelparous, dorid nudibranch Adalaria proxima (Alder & Hancock) to evaluate variation in fitness-related traits. The six populations spanned the geographic range in the northern British Isles: NE England (Cowling Scar), E Scotland (Kinkell Braes), NW Scotland (Loch Eriboll), W Scotland (Cuan Ferry), Northern Ireland (Portaferry), and N Wales (Menai Bridge). Nudibranchs from five sites were collected in July to August 1992 as post-metamorphic juveniles and were laboratory-reared under the same conditions of ambient temperature and photoperiod for up to 10 months and the completion of spawning. Individuals from the sixth site were added to the experiment in December 1992. Growth was monitored every 2 weeks, and reproductive performance was expressed as a weight-adjusted dimensionless index (ΣRI) of each individual's spawnings summed over the reproductive period. In general, larger nudibranchs produced larger first spawn masses and more total spawn than did smaller nudibranchs, but these size-related trends were observed only in some populations. The patterns of energy partitioning to spawnings varied significantly among populations, from allocations of a large number of eggs to few spawn masses (Loch Eriboll) to production of many small spawnings over a long spawning period (Portaferry). There was no relationship between maximum body size and the amount of spawn produced after the first spawning, nor to the length of the spawning period or the number of spawn produced. Both Menai Bridge and Kinkell Braes had low mean population ΣRI, reflecting a very poor reproductive performance, given their large maximum (pre-spawning) body sizes. By contrast, the Loch Eriboll, Cuan Ferry, and Portaferry populations all displayed high mean population ΣRI, albeit as a result of differing combinations of numbers and sizes of spawn masses and duration of the spawning period. This high variance of reproductive allocation among populations, and previous evidence of relatively stable among-population differences in allozyme frequencies, adult color, and embryo characteristics suggest very restricted larval transport of lecithotrophic larvae of A. proxima. Received: 10 December 1998 / Accepted: 23 March 2000     

Determination of Baghouse Performance from Coal and Ash Properties: Part I

Baghouse performance at utility coal-fired power plants is determined by baghouse design, operating procedures, and the characteristics of the ash that is collected as a dustcake on the fabric filter. The Electric Power Research Institute has conducted laboratory research to identify the fundamental properties of dustcake ash that influence baghouse performance. A database was assembled including measured characteristics of dustcake ash and data describing operating parameters and performance of full-scale and pilot-scale baghouses. Semi-empirical models were developed that describe the effects of particle morphology, particle size, ash cohesivity and ash chemistry on filtering pressure drop and particulate emissions. Cohesivity was identified as the primary ash characteristic affecting baghouse performance. Predictions of performance can be based on physical or chemical characterizations of the ash to be filtered. Part II of this article will discuss the effects of ash and coal chemistry, and baghouse design and operation on performance.     

Relationships between water quality, habitat quality, and macroinvertebrate assemblages in Illinois streams

The influence of specific stressors, such as nutrient enrichment and physical habitat degradation, on biotic integrity requires further attention in Midwestern streams. We sampled 53 streams throughout Illinois and examined relationships between macroinvertebrate community structure and numerous physicochemical parameters. Streams were clustered into four major groups based on taxa dissimilarity. Habitat quality and dissolved nutrients were responsible for separating the major groups in a nonmetric multidimensional scaling ordination. Furthermore, the alignment of environmental factors in the ordination suggested there was a habitat quality-nutrient concentration gradient such that streams with high-quality habitats usually had low concentrations of nutrients. Discrimination by community measures further validated the major stream groups and indicated that forested streams had generally higher biological integrity than agricultural streams, which in turn had greater integrity than urban streams. Our results demonstrate that physical habitat degradation and nutrient pollution are important and often confounded determinants of biotic integrity in Illinois streams. In addition, we suggest that management of Midwestern streams could benefit from further implementation of multivariate data exploration and stream classification techniques.     

Effects of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites on cricket (Acheta domesticus) survival and reproductive success

The effect of two major hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), on cricket (Acheta domesticus) survival and reproduction was studied. RDX metabolites did not have adverse effects on cricket survival, growth, and egg production. However, MNX and TNX did affect egg hatching. MNX and TNX were more toxic in spiked-sand than in topical tests. TNX was more toxic to egg than MNX. Developmental stage and exposure time affected hatching. After 30 days exposure to MNX or TNX, the EC20, EC50, and EC95 were 47, 128, and 247 microg/g for TNX, and 65, 140, and 253 microg/g for MNX in topical tests. The ECs for 20, 50, and 95 were 21, 52, and 99 microg/g for MNX, and 12, 48, and 97 microg/g for TNX in sand. No gross abnormalities in cricket nypmhs were observed in all experiments indicating that neither TNX or MNX is teratogenic in this assay.     

Perchlorate in fish from a contaminated site in east-central Texas

Perchlorate, a known thyroid endocrine disruptor, contaminates surface waters near military instillations where solid fuel rocket motors are manufactured or assembled. To assess potential perchlorate exposure to fish and the human population which may feed on them, fish were collected around the Naval Weapons Industrial Reserve Plant in McLennan County, TX, and analyzed for the presence of the perchlorate anion. The sampling sites included Lake Waco and Belton Lake, and several streams and rivers within their watersheds. The general tendency was that perchlorate was only found in a few species sampled, and perchlorate was not detected in every individual within these species. When detected in the fish, perchlorate tissue concentrations were greater than that in the water. This may be due to highly variable perchlorate concentrations in the water coupled with individual-level variation in elimination from the body, or to routes of exposure other than water.     

Synthesis of3H- polyethylene and its use for fate studies on degradable plastics

Determining the fate of xenobiotic materials in the environment can be aided by the use of radioactive isotope technology. Previous research on the degradation of polymers such as polyethylene (PE) was aided by the utilization of radiotracers. In order to study the environmental fate of degradable (PE/starch) plastics, we synthesized³H-labeled PE. Results of soil incubation studies indicate that only minimal degradation of the PE component, as indicated by the production of water-soluble metabolites, occurred during 2 years of incubation in soil. Despite the minimal degradation, the³H label did not allow for detection of the degradation products. In addition, the³H-PE was particularly useful for tracing the fate of degradable plastics after consumption by terrestrial isopods. The detection of aqueous-soluble radioactivity in isopod frass was used to indicate degradation of the plastic film.     

Water Quality Functions of Riparian Forest Buffers in Chesapeake Bay Watersheds

/ Maryland, Virginia, and Pennsylvania, USA, have agreed to reduce nutrient loadings to Chesapeake Bay by 40% by the year 2000. This requires control of nonpoint sources of nutrients, much of which comes from agriculture. Riparian forest buffer systems (RFBS) provide effective control of nonpoint source (NPS) pollution in some types of agricultural watersheds. Control of NPS pollution is dependent on the type of pollutant and the hydrologic connection between pollution sources, the RFBS, and the stream. Water quality improvements are most likely in areas of where most of the excess precipitation moves across, in, or near the root zone of the RFBS. In areas such as the Inner Coastal Plain and Piedmont watersheds with thin soils, RFBS should retain 50%-90% of the total loading of nitrate in shallow groundwater, sediment in surface runoff, and total N in both surface runoff and groundwater. Retention of phosphorus is generally much less. In regions with deeper soils and/or greater regional groundwater recharge (such as parts of the Piedmont and the Valley and Ridge), RFBS water quality improvements are probably much less. The expected levels of pollutant control by RFBS are identified for each of nine physiographic provinces of the Chesapeake Bay Watershed. Issues related to of establishment, sustainability, and management are also discussed.KEY WORDS: Riparian forest buffers; Chesapeake Bay; Nonpoint source pollution; Nitrogen; Phosphorus; Sediment     

Evidence of natural organochlorine formation in peat bogs

Peat samples from four ombrotrophic and two minerotrophic peat bogs in New Brunswick, Canada, have been analyzed for polychlorinated dioxins and furans (PCDD/DF's) as well as other organochlorine compounds. Data from each bog show occasional low levels of 2,3,7,8-substituted tetra-through octachloro dioxins and furans. Mono-through trichlorodioxins and furans have also been identified.

A consistent pattern was observed among the TCDD's and TCDF's which was reproducible across all peat samples analyzed. A single TCDF isomer (2468-TCDF) predominates over all other isomers whereas two isomers of TCDD were prominent (1,3,6,8-TCDD and 1,3,7,9-TCDD). This distinct isomer pattern is present at all depths and is different from that of atmospheric deposition or known sources of PCDD/DF's (eg. fly ash, pulp and paper effluent etc). The pattern is replicated with in vitro oxidative coupling of 2,4-dichlorophenol at pH 2.9 using a commercially available chloroperoxidase from the fungus Caldariomyces fumago.

Significant incorporation of ³⁶Cl-occurred in peat. Autoclaving decreased incorporation while adding casein hydrolysate increased it. The incorporation mirrored the metabolic activity (CO₂ production) of samples consistent with organochlorine synthesis being due to biological activity.

Total Organic Halide (TOX) levels in peat show a wide range in values reaching ca. 1000 ppm at mid-depth in the ombrotrophic Kelly's Bog. TOX in Kelly's Bog occurs at all depths and, since the topography probably excludes leaching from surrounding areas, a local origin of organochlorines is suggested.

Chloroform and a range of chlorinated aromatic compounds (chlorophenols, chlorophenoxy and chlorobenzoic acid derivatives) have also been identified in peat.

Our findings to date are consistent with hypothesis for a biogenic origin for at least some of the organochlorine compounds, including some of the PCDD/DF's, found in peat bogs.     

Application of SMR to Modeling Watersheds in the Catskill Mountains

Very few hydrological models commonly used in watershed management are appropriate for simulating the saturation excess runoff. The Soil Moisture Routing model (SMR) was developed specifically to predict saturation excess runoff from variable source areas, especially for areas where shallow interflow controls saturation. A recent version of SMR was applied to two rural catchments in the Catskill Mountains to evaluate its ability to simulate the hydrology of these systems. Only readily available meteorological, topographical, and landuse information from published literature and governmental agencies was used. Measured and predicted streamflows showed relatively good agreement; the average Nash–Sutcliffe efficiency for the two watersheds were R ²=72% and R ²=63%. Distributed soil moisture contents and the locations of hydrologically sensitive areas were also predicted well.