No description available.

No description available.

No description available.

M.S.

This study was undertaken to investigate the mineral nutrition of aquatic Hyphomycetes by determining the mineral requirements of several species. On the basis of rapidity and renroducibility of growth, four species were selected, These were Heliscus lugdunensis Webster (Nectria lugdunensis webster), Flagellospora penicillioides Ingold (Nectria penicillioides Ranzoni), Clavariopsis aquatica DeWildeman, and Lunulospora curvula Ingold. These were grown in liquid culture on a rotary shaker at constant temperature. The containers and other equipment were cleaned by acid washing. When necessary to establish a nutritional reguirement for an element, the nutrient salts were purified by the phosphate adsorption and dithizone methods. In addition to nutrient salts and purified water, the media contained only glucose. Since all the species except Clavariopsis aquatica DeWildeman grew well for many transfers and approximately two years on this completely defined medium, without vitamins or amino acids being provided, it is concluded that they do not require these nutrients. Whether an element was required, and in what concentration, was decided on the basis of the amounts of growth obtained with various concentrations of the element in the initial media. Growth was measured as the dry weight of the mycelium from 100 ml of medium and the values from four replicates were averaged. Phosphorus, calcium, nitrogen, zinc, iron, magnesium, and sulfur requirements were demonstrated for all four species. Efforts to demonstrate requirements for potassium were unsuccessful. Manganese toxicity was demonstrated for Clavariopsis aquatica DeWildeman and a manganese requirement was suggested for Flagellospora penicillioides Ingold (Nectria penicillioides Ranzoni). The results suggested a molybdenum requirement for Heliscus lugdunensis Webster (Neetria lugdunensis Webster) and Lunulospora curvula Ingold, a boron requirement for H. lugdunensis and toxicity for C. aquatica, and a copper requirement for F. penicillioides. Approximately 0.50, 0.25, 0.50-1.00, and 0,.05-0.10 milli-moles per liter of phosphate were required to obtain maximum dry weight yields of Heliscus lugdunensis Webster (Nectria lugdunensis Webster), Flagellospora penicillioides Ingold (Nectria penicillioides Ranzoni), Clavariopsis aguatica DeWildeman, and Lunulospora curvula Ingold respectively. Calcium concentrations of 7.5, 50, 7.5, and 25 milli-moles per liter supported maximum growth of these species in the same order. All four were able to utilize ammonium nitrogen, nitrate nitrogen, or ammonium nitrate to produce about the same amounts of growth. C. aquatica was apparently able to use nitrate nitrogen only in the presence of an unidentified nutrient and this is interpreted as indicating a role for that nutrient in the nitrate metabolism of this species. Fifteen milli-equivalents per liter of ammonium nitrate, ammonium, or nitrate nitrogen was adequate to obtain maximum dry weight yields of H. lugdunensis. Five milli-equivalents per liter of ammonium nitrate, 15 of ammonium, and 35 of nitrate nitrogen supported maximum growth of F. penicillioides. As little as 5 milli-equivalents per liter of ammonium nitrate or ammonium nitrogen was optimal for C. aguatica and 5 milli-equivalents per liter of any of the three nitrogen sources was optimal for L. curvula. The optimal nitrate concentration for C. aquatica was not determined. There is an obvious advantage to a single medium on which a great number and wide variety of species may be grown. The author is of the opinion that a far greater advantage lies in the use of a completely defined medium on which one or more organisms may be reproducibly grown, Such media are suggested and their employment is strongly urged. Only in this manner can considerable morphological and physiological variations be avoided. / Ph. D.

Identifying the processes and mechanisms that govern communities of organisms is the main goal of community ecology. Locally operating mechanisms such as environmental filtering, in which the environment determines what species are found in a given location, as well as regional processes such as dispersal have all been identified as potential drivers of community processes. However, the relative importance of these drivers may vary temporally and spatially. In dendritic stream networks, headwater streams are isolated when compared to more centrally located mainstem stream sections. I investigated the potential for stream networks to influence the relative influence of local and regional processes via a survey and field experiment based approaches. I found that headwater streams can influence mainstem stream communities, potentially as a result of the dispersal of organisms or abiotic materials. Additionally, I demonstrated that macroinvertebrate communities in headwater streams respond more strongly to manipulations of local environment than do mainstem streams, both in terms of community composition as determined taxonomically and as functional traits. These results indicate that headwater streams may be affected differently than mainstem streams by anthropogenic activity and as such, management strategies and restorations may need to be specifically tailored to address the relative influences of local and regional processes at varying points within a stream network. / Ph. D.

I investigated life history traits and secondary production of populations of Goniobasis proxima in four streams from July 2005 to June 2006. Measurements of canopy cover, conductivity, alkalinity, temperature, and nitrate-nitrogen (NO3-N), as well as snail size, density, and occupied substrate were taken monthly for each stream. Snail growth rates were determined in an aquarium for 10 size classes and secondary production was estimated as the summed product of size class growth rates and field biomass measurements. Size class production estimates tracked biomass with intermediate to larger sized snails dominating production, despite smaller snails growing faster. Production estimates across streams ranged from 1,400 mg m-2 yr-1 to 22,183 mg m-2 yr-1 with noticeable summer highs and winter lows. Annual turnover was slow (0.43-0.49) owing to slow growth and long development time. Snails preferred leaves/wood as a substrate to occupy over rock and sand and showed no appreciable grazing effect on the epilithon community. / Master of Science

The goals of this study were 1) to integrate several aspects of detrital dynamics with the composition and production of shredder populations and 2) to present evidence of a shredder regulatory role in headwater strewn detrital dynamics. The importance of leaf shredding aquatic insects (shredders) in the breakdown of leaf detritus and production of particulate organic matter (POM) was evaluated in three permanent and three temporary southern Appalachian headwater streams. Shredder population dynamics were compared to several stream detrital parameters: CPOM breakdown rates, POM concentrations, average POM particle sizes, and POM transport. In general, permanent streams with the greatest shredder densities, biomass, and annual production rates had the fastest leaf breakdown rates, highest low-flow POM concentrations, largest average POM particle sizes and greatest POM transport estimates. Temporary stream environments depressed shredder populations resulting in a reduction of detrital processing and POM transport. Microbial activity, stream velocity, base-flow discharge, and water temperature did not correlate with detrital parameters for comparisons between permanent and temporary streams. Shredder contribution to total benthic CPOM breakdown in the six study streams ranged from 31% in a permanent stream to 1% in a temporary stream. / Ph. D.

The potential relationship between riparian arachnids and aquatic insect productivity was assessed in forest streams throughout the central South Island of New Zealand. Initially, a survey was conducted of thirty seven, first-third order forest streams. Streams were selected to represent a range of benthic invertebrate standing crops (as a surrogate measure of "productivity") from Banks Peninsula streams with relatively high benthic invertebrate densities to acid mine drainage streams near Reefton that were almost devoid of aquatic life. At each site benthic invertebrate densities and biomass were measured in riffle habitats and adjacent gravel bars were sampled for terrestrial invertebrates. At a sub-set of 16 sites, a 20 metre longitudinal web-building spider survey was conducted along each bank of the stream. As an additional component, a 20 metre transect starting at the stream margin and running perpendicularly into the forest was used to survey the density of web-building spiders with increasing distance from the stream. Results from the survey of in-situ stream insect biomass and gravel bar invertebrates showed a strong relationship between aquatic insect biomass and the biomass of riparian arachnids (R2 = 0.42, P < 0.001) having accounted for potentially confounding factors such as stream size, elevation, substrate and disturbance. The 20 metre longitudinal survey showed that streams with the highest in-situ insect biomass had significantly higher densities of web-building spiders along their banks (R2 = 0.28, P < 0.05), having accounted for potential confounding variables of elevation, habitat architecture and stream and channel width. The stream to forest survey showed a strong exponential decay in web-building spider densities with increasing distance from the stream (R2 = 0.96, P < 0.0001). Regardless of stream productivity web-building spiders were most abundant at the stream margins and rapidly declined to very low densities 20 metres from the stream. In order to further test the relationship between riparian web-building spider densities and stream insect productivity, a stream fertilization experiment was conducted on six first-second order streams in the Maimai experimental catchment, Reefton. Three streams were enriched by the addition of a fertiliser solution mainly consisting of sodium nitrate for seven months, and the other three streams were used as controls. Water chemistry, benthic invertebrate communities, emerging aquatic adults, and the densities of web-building spiders along the stream corridor and in the forest were monitored in three seasons (spring, summer and autumn) over the course of the nutrient-addition. By the end of the experiment, conductivity was significantly higher in nutrient-addition streams than in the control streams (F = 80.5, P < 0.001), but chlorophyll concentrations showed no significant differences between treatments. Both benthic mayfly densities (F = 6.15, P < 0.05) and the biomass of adult aquatic dipterans (Chironomidae, Simuliidae) (F = 9.25, P < 0.01) were significantly higher in nutrient-addition streams in the last sampling round. Spiders recorded from intercept traps indicated that by the end of the experiment spider activity was significantly higher within 2.5 metres of the nutrient-addition streams (F = 5.70, P < 0.01). However, seasonal densities of web-building spiders along the stream margin and in the forest decreased with no significant differences observed between nutrient-addition and control streams. The results from these studies indicate that adult insects emerging from streams represent an important source of prey that could influence the biomass and abundance of riparian arachnids. Additionally, the results imply that stream productivity and size could mediate the strength of the interaction between riparian and stream habitats. Moreover, feedback mechanisms present in both systems could have implications for such interactions. The elevated densities of web-building spiders observed at the stream margin led to the proposal of the "Highway Robber" hypothesis. This hypothesis suggests that such higher densities of spiders are the result of increased insect activity along the stream corridor: the emergence of adult aquatic insects was predicted to vary less over temporal and spatial scales than that of terrestrial insects due to the poorly synchronized life histories in many New Zealand stream insects. I conclude by suggesting that there are numerous anthropocentric perturbations such as loss of heterogeneity, introduced species, pollution and habitat degradation that could undermine and decouple the intimate linkages between aquatic and terrestrial ecosystems.

Limitations from reduced light and increasing water depth on Nelumbo lutea seedlings were determined in tank experiments. Survival was high in all tested light levels. Total biomass increased significantly with increasing light. Biomass allocation shifted significantly to root production between 3 and 6 weeks in the 10 and 24% levels. Survival decreased with increasing planting depth, and biomass of survivors reduced significantly between 0.5, 1.0, and 1.5 m depths. Nelumbo lutea and Myriophyllum spicatum populations were monitored for one season in a 0.7 ha pond to track changes in species dominance. Myriophyllum spicatum dominated early, and N. lutea dominated from July through October, suppressing M. spicatum at all depths. Competitive interactions between N. lutea and M. spicatum were investigated for two seasons in a container experiment situated within a pond. Where established, N. lutea dominated in the presence of M. spicatum. However, N. lutea could not be established in depths greater than 1 meter.