The potential for life to control its environment was first suggested by Lovelock (1972). Charlson et al (1987) proposed a role for marine planktonic ecosystems in global climate regulation via the production and ventilation to the atmosphere of dimethylsulphide (DMS), a by-product of phytoplankton metabolism. Once in the atmosphere DMS contributes to the formation of cloud condensation nuclei, and increases the amount and brightness of cloud. This affects the albedo of the planet, reflecting more incident sunlight back into space, and cooling the earth. In common with many other 'hypotheses' regarding complex adaptive systems, the hypothesis proposed by Charlson et al (1987) is not experimentally testable. The production and ventilation to the atmosphere of DMS is the result of complex interactions between biological, chemical and physical processes. Consequently, increasing use is being made of mathematical models that simulate these processes to advance understanding of it (Archer et al. 2002). This study examines one of the fundamental mechanisms proposed by the Charlson et al (1987) hypothesis, that increasing global temperatures will lead to increased ventilation of DMS from the ocean to the atmosphere. The study develops one-dimensional biogeochemical models of DMS production by upper ocean ecosystems, based on the model proposed by Gabric et al. (1993b). The models are examined to elucidate their fundamental mathematical properties, and are subjected to sensitivity analysis to identify important processes and parameters. These investigations identify a simpler model that can reproduce the predictions of the Gabric et al. (1993b) model. Predictions derived from model simulations forced by climatologies of measured physical data are compared to a global database of measurements of sea surface DMS concentrations, and to observed depth profiles of DMS in the upper ocean. These comparisons confirm that all models are in good qualitative agreement with measured data. The fifteen global climate prediction models currently in use around the globe all predict substantial warming effects from the ventilation of anthropogenic carbon dioxide to the atmosphere. A simplified DMS model is calibrated to climatologies of Antarctic chlorophyll and DMS data and reproduces the data with great precision. The calibrated model is applied in global warming scenarios to 'test' the efficacy of the mechanism proposed by the Charlson et al (1987) hypothesis. This simulation provides evidence that the response predicted by the hypothesis is indeed feasible, and that substantial increases (up to 45%) in the ventilation of DMS to the atmosphere could be possible in some circumstances. The results of the modelling study provide impetus for further examination of field data. If couplings between marine biota and atmosphere are feasible, then they may be operating contemporarily, and may be detectable. Atmospheric DMS is oxidised to form aerosols (Miller et al. 2002) that influence the aerosol optical depth of the atmosphere. Archives of remote sensed ocean chlorophyll a concentration and aerosol optical depth are examined for evidence of the biologically mediated couplings. A clear coupling between aeolian dust and marine phytoplankton is evident from this analysis, suggesting that the deposition of dust from the atmosphere is a major factor controlling phytoplankton growth in many parts of the ocean. A second coupling between marine phytoplankton and atmospheric aerosols is also detected. This coupling is apparently not related to dust and is symmetrical about the equator, despite the substantial differences in the atmospheres and oceans of each hemisphere. It is speculated that this coupling may reflect the influence of the ventilation of DMS produced by marine phytoplankton on the atmosphere. This thesis provides new evidence supporting the important role of marine ecosystems in global climate regulation by the production of DMS. This evidence is principally obtained from a biogeochemical modelling approach, but is supported by analyses of empirical data. The concordance of results obtained from different approaches suggests that the contribution of marine ecosystems to global climate regulation is real, important and currently active.

This study has contributed to the development of the reference condition approach in disturbed landscapes. The reference condition approach has been an important development for the bioassessment of aquatic ecosystems by providing a practical tool for the accurate assessment of river condition. The selection of appropriate reference sites is critical to the success of the predictive model in terms of being able to distinguish between natural variation in biota and the effects of human disturbance. Capturing natural variability and explaining it is a key difference between the reference condition approach and other study designs (e.g. before/after/control/impact). Natural disturbances such as drought or bushfire can significantly alter the ecological condition of streams, and although the ecological condition of streams affected by natural drought or bushfire is part of the natural cycle, this natural variation of the ecological condition is rarely incorporated into many study designs because of a mismatch in time scales. Human disturbance has also significantly altered the condition of landscapes through the development of agriculture and urbanisation. In urban or agricultural landscapes it can be impossible to locate streams that have not been modified by human activity for use as a reference condition. This study looked at the effects of natural disturbance on the reference condition, in terms of the way natural disturbance affects the prediction of stream condition and also the incorporation of the condition of streams experiencing natural disturbance into a predictive model. Additionally this study identified an alternative benchmark for modified landscapes based on the presence of good management practices for river protection, and tested this benchmark for the assessment of streams impacted by urbanisation. Drought and bushfire regularly disturb aquatic ecosystems in Australia, and affected reference sites in the ACT and South Coast region of New South Wales in 2002 and 2003. Drought and bushfire conditions affected macroinvertebrates and environmental variables across these streams, and the majority of sites were assessed as significantly impaired using regional AUSRIVAS (AUstralian RIVers Assessment System) models. This indicated the existing reference conditions for these regions had not incorporated the ecological conditions of reference sites suffering these natural disturbances. Many of the environmental variables used to predict the condition of streams were also affected by drought or bushfire. The changes to environmental variables affected how sites were assessed in models, but the overall assessment was not significantly changed from the initial assessment that drought or bushfire had significantly impaired the ecological condition. To reduce potential assessment errors associated with changes to predictor variables an attempt was made to construct new models with changeable variables excluded. However, it was not possible to completely exclude these types of variables, and subsequent models were no better than the original models in terms of changes to predictor variables affecting the generation of expected taxa lists. The changes to environmental variables did not affect the actual assessment of site condition because although group membership probabilities were changed the probabilities of taxon occurrence did not change significantly. The different reference site groups all contained some common taxa that occurred at most sites and even when group probabilities changed this did not change the probability of these taxa occurring at a test site. For regional models, such as the ACT or NSW South Coast, changes to predictor variables may not significantly affect the assessment of site condition. Incorporating reference sites under drought conditions into a predictive model was an effective way of discriminating the effects of drought from human disturbance. The model only provided two different ecological conditions, a single drought measurement and a single non-drought measurement, so the model did not fully encompass the potential natural variability. The model has value as a starting point and was effective in distinguishing sites affected by human disturbance from sites affected by drought. Good Management Practice (GMP) for river protection is any intervention that minimises human impact on stream condition. Urban sites protected by GMP were used as an alternative benchmark to a minimally impacted reference condition. The criteria used to select reference sites were not sufficiently robust to detect a significant benefit of GMP on physical or chemical characteristics of protected sites, compared to sites without GMP. In general however, the physical and chemical condition of GMP sites was better than sites without GMP and there were significant differences in macroinvertebrate assemblages of GMP and non-GMP sites. A refinement to the site selection process is proposed to include a specific assessment of GMP effectiveness for the protection it is designed to provide. This will substantially improve the robustness of a GMP benchmark and provide a clearer picture of the factors controlling biota in urban streams protected by GMP. The GMP benchmark was developed into a predictive model for the assessment of urban stream health, and in terms of the assessment of test site condition, it did not differ significantly from a model using minimally impacted sites. The purpose of the GMP benchmark was to provide an alternative reference condition for the assessment of stream health in modified landscapes when minimally impacted sites are unavailable or provide an unattainable benchmark. The GMP reference condition as an alternative can provide an attainable and realistic benchmark. The development and application of the suggested site selection protocol will improve the robustness of the GMP benchmark and better account for natural variation in the biota and physical characteristics of the sites used to determine the reference condition.

Marine ecosystems are increasingly being subject to human impact from diverse recreational and commercial activities, not necessarily restricted to those of a marine nature. This has significant implications for biodiversity. The large dog cockle, Tucetona laticostata, once occurred live in Rangitoto Channel, Hauraki Gulf, although this species no longer appears to occur there, most likely as a consequence of repeated dredging and channel excavation and continued siltation. Tucetona laticostata still occurs in a few isolated pockets of sea bed throughout Hauraki Gulf, particularly off Otata Island, part of the Noises complex of islands, where it resides partially buried in shell and rock gravels in shallow water (to 15 metres depth). The shells of T. laticostata collect in large post-mortem deposits in an area ramping from the sea bed off southwestern Otata Island. These mounds differ significantly in structural complexity from those of adjacent, extensively fragmented shell and rock gravels. Using the mounds of T. laticostata shell as a proxy for structural complexity, in order to appraise the effect of complexity on benthic-invertebrate diversity, the sea bed off southwestern Otata Island was sampled quarterly at two depths and in both T. laticostata shell mounds and adjacent extensively fragmented shell and rock gravels. These data were complemented with those from additional surveys around Otata Island, and off eastern Motutapu Island to determine the distribution and composition of benthic-invertebrate community assemblages throughout the region, and from concurrent surveys throughout the Waitemata Harbour and inner Hauraki Gulf to determine the current distribution of T. laticostata in this region. The number of benthic invertebrate species and individuals within T. laticostata habitat almost always was higher than that occurring within extensively fragmented shell- and rock gravel habitat, with densities to 142,385 individuals m-2 encountered. Temporal and spatial variations in benthic community structure also are reported for the two habitats, T. laticostata-based shells and extensively fragmented shell- and rock gravels. The numbers of species were higher amongst samples collected off the southwestern and eastern sides of Otata Island than elsewhere around this island, or of eastern Motutapu Island. Of the 351 species reported from all Otata and Motutapu Island samples combined, 73% of them occurred off southwestern Otata Island, 30% of which were found exclusively within T. laticostata shell habitat, and 10.5% within extensively fragmented shell and rock gravel habitat. The sea bed off southwestern Otata Island is regularly, seasonally dredged by recreational scallop fishers, in addition to being a popular small-vessel anchorage site. Both of these activities, dredging and anchorage, stand to reduce substratum complexity by fragmentation and dispersal of the valves of T. laticostata. Given the unique benthic invertebrates reported from T. laticostata shell deposits reported from southwestern Otata Island, any activity that damages the shells of this species, regardless of whether they are live or dead, is likely to result in loss of biodiversity. Admittedly, many of species identified as major contributors to differences in benthic invertebrate assemblages between T. laticostata shell-based habitats and those of extensively fragmented shell and rock gravels are not particularly charismatic or large, but each likely plays a role in local food webs and/or sediment and water column chemistry. It was not the intention of this research to determine the effects of anthropogenic disturbances like dredging or vessel anchorage on benthic-invertebrate communities off southwestern Otata Island. However, given the reported differences in species diversity within the structurally complex substratum provided by T. laticostata, conservation of biogenic reef-forming species like it might be a prudent, precautionary measure to take.

Pisolithus is an important ectomycorrhizal genus world-wide, however to date we remain largely ignorant of the genetic and functional variation that exists within isolates of this genus. Fifty-three isolates of Pisolithus were obtained from various locations in central and eastern Australia and genetic variation within the isolates was assessed using ITS-RFLP and ITS sequencing analyses. RFLP analysis initially grouped the isolates into eight RFLP types. Neighbour-joining analysis of ITS sequences with Pisolithus ITS sequences available in databases clustered the majority of isolates into four groups within two major clades, each comprising isolates of similar basidiospre characteristics. Most Australian isolates correspond with recent provisional descriptions of P. albus or P. marmoratus. One isolate (LJ30) had low sequence identity (61.6-78.0%) to the other isolates and probably represents a separate undescribed Australian species. Significant intraspecific variation was observed in ITS-RFLP profiles for the putative P. albus isolates, suggesting that the sole use of RFLP analysis in diversity assessment may over-estimate Pisolithus species richness. Investigations were also initiated to identify if a relationship exists between genetic and physiological diversity in Australian Pisolithus. It is, however, clear that extensive physiological variation exists in Australian Pisolithus isolates. The size and distribution of genets of Australian Pisolithus species I and II ( putative P. albus and P. marmoratus) was also assessed using microsatellite-primed PCR to gain a better understanding of the likely distribution of underground mycelial networks and possible reproduction strategies in native soils. The data demonstrate that both species have the ability to be long-lived and extend for significant distances in native soils in undisturbed conditions. The field site for Pisolithus species I, however, also contained of a large number of small individuals suggesting that this species may employ a life-history strategy combining r-, C and S characteristics depending on local soil conditions / Doctor of Philosophy (PhD)

<p>Human activities have caused acidification of freshwater systems on a large scale resulting in reduced species diversity and ecological functioning in many lakes and streams. However, many naturally acidic freshwater systems have also been found, for instance in northern Sweden. In regions where such naturally acidic aquatic ecosystems have prevailed over evolutionary periods, species diversity and ecological functioning are not automatically impaired due to possible adaptation to the putatively adverse environmental conditions. I studied species diversity patterns and ecological functioning in anthropogenically acidified, naturally acidic, circumneutral, and limed streams to test the adaptation hypothesis and examine the ecological effects of variation in naturally acidic water chemistry. Species diversity was studied using benthic macroinvertebrates, while functioning was modelled using the decomposition rates of leaf litter. In accordance with the evolutionary species pool hypothesis, species richness was reduced more strongly in regions with anthropogenic than natural acidity when compared to circumneutral streams, supporting the adaptation hypothesis. In contrast, the patterns in ecological functioning along the pH-gradients did not differ between regions with anthropogenic and natural acidity, likely resulting from compensation: the biomass of tolerant taxa probably increased which thus rescued the loss in functioning otherwise mediated by the more sensitive taxa. Furthermore, the naturally variable acidic water chemistry clearly supported distinct macroinvertebrate assemblages, as was reflected in differing patterns of species diversity and ecological functioning. Such naturally acidic waters that were rich in dissolved organic carbon supported higher ecosystem process rates and lower species diversity than waters that contained little dissolved organic carbon. Upon liming naturally acidic streams microbial leaf decomposition increased, whereas shredding decreased along with changes in shredder abundances. The abundance of large caddisflies decreased, while the abundance of small stoneflies increased. The results suggest that various types of benthic macroinvertebrates with varying levels of adaptation and tolerance inhabited the hydrochemically variable naturally acidic streams. The distributions of macroinvertebrates in response to different pH levels and differences in acid quality and how these distributions translate into varying patterns of species diversity and ecological functioning are worthy of further investigation. This will likely improve our understanding of how such naturally acidic streams and their biota can be successfully managed.</p>

<p>Biological diversity is one out of four dimensions, characterizing the subject of Biology ac-cording to the school curriculum. As a concept, biological diversity had its break through at the UN environmental conference in Rio de Janeiro in 1992, where the convention about bio-logical diversity, named CBD, was signed. According to the convention, almost all the na-tions of the world have engaged themselves to preserve the national diversity of species, in-cluding the diversity of genetics and ecological systems.</p><p>This thesis focuses the biological diversity from the perspective of school books. The aim is to find out how the biological diversity is presented in biology books for students aged 12-15 years.</p><p>In 1994, the current Swedish secondary and high school curriculum called LPO-94 was pre-sented. The biology books used in this study were published between 1994 and 2007, all of them exist in many editions and are published by three different publishers.</p><p>The conclusion of the study is that all the biology books that were examined have reached different levels of the development in the field of biological diversity.</p>

The Lamprey Eel Decline project conducted by the Confederated Tribes of Siletz Indians (CTSI) combined traditional ecological knowledge, scientific research and geographic information science. CTSI wanted to learn why the Pacific lamprey (Lampetra tridentata), a culturally and ecologically important species, was declining in the streams within their native land area. The project included interviewing native elders, characterizing stream habitat, monitoring water quality, creating a geographic information system (GIS) and educating tribal members on the cultural and ecological importance of the Pacific lamprey. Dynamic segmentation, a GIS data structure, was used to link standard stream survey data on the river unit scale to a base stream coverage (1:24,000). Dynamic segmentation efficiently associates georeferenced data to a linear feature, thus allowing the data to be readily assessable on desktop computer systems. To be more useful to the tribal and local resource managers, it is recommended that these GIS coverages of aquatic habitat should be used in conjunction with additional data coverages and basic regional models for watershed analysis and better management of aquatic ecosystems. / Graduation date: 2001

As fishery production and habitat quality continues to experience declines, there is a growing need to improve the scientific methodologies used to assess and sustain economically and ecologically important fisheries. This requires a sound understanding of the life histories and population dynamics of each species, and development of a robust framework for population modeling. Realization of the multi-species nature of fisheries has prompted a shift towards ecosystem-based approaches to modeling. To evaluate alternative methods for modeling predator-prey interactions within a physically variable coastal-estuarine ecosystem, a food web of national economic and ecological significance comprised of Atlantic menhaden (Brevoortia tyrannus), striped bass (Morone saxatilis), and bluefish (Pomatomus saltatrix) is considered in this study. Understanding the dynamics of biological communities such as this is challenging and requires the formulation of realistic mathematical models. This should be a stepwise process in which the underlying assumptions, parameter sensitivities, and fundamental behaviors of interacting species dynamics described by relatively "simple" to more "complex" models are delineated and quantified. In this study two alternative multispecies modeling frameworks were utilized to evaluate the dynamic interactions between predator and prey populations, and to understand the influence of fisheries and environmental temperature change on predator-prey and food chain communities. First, relatively "simple," age-independent, predator-prey and food chain models representing generalized, ecological-scale interactions between different trophic groups were developed and analyzed. Sensitivity analyses revealed the relative importance of model parameters and the effect of varying levels of fishing mortality on model dynamics. Overall, the predator-prey and food chain models were shown to be a valuable tool for understanding general patterns in the dynamic behavior of interacting populations. Next, an environment-dependent, age-structured, Atlantic coast spatial dynamic multispecies model was investigated. This more complex model links individual-scale bioenergetic processes controlling growth to ecological-scale rates of natural and predation mortality. Simulations were performed using recent stock assessment estimates of fishery condition and stock sizes to evaluate the nature and magnitude of linkages among menhaden and their key predators, specifically bluefish. This ecosystem model was demonstrated to provide valuable insights into the dynamics of menhaden and bluefish given the underlying dynamics and forcing in the Atlantic States fishery coastal ocean ecosystem. Additionally, the influence of environmental temperature on both modeling frameworks was investigated. This iterative process of model development and analysis advances the current understanding of the species and ecosystem of interest, and ultimately provides an improved basis for multispecies fisheries assessments.

The greater Everglades ecosystem, including Florida Bay, has undergone significant anthropogenic manipulation over the past century. These actions resulted in a series of ecologically undesirable events in the Everglades ecosystem, prompting passage of the Comprehensive Everglades Restoration Plan (CERP). It is necessary to understand the variability in, and relationship between, salinity and ecology to fully evaluate the potential effects of CERP on Florida Bay. A seven-year dataset on surface salinity along with eleven-year and eight-year datasets on mesozooplankton and planktivorous fish were analyzed. Overall, mean Bay-wide salinity varied from a low of 24.2 just after the passing of Hurricane Irene in October 1999 to a high of 41.8 near the end of a drought period in July 2001. Bay-wide mean salinity exhibited dramatic decreases, up to 0.5 per day, whereas increases in bay-wide salinity were slower, with a maximum rate of 0.1 per day. Meteorological phenomena, such as tropical cyclones and ENSO, dramatically altered the salinity patterns of Florida Bay on interannual time scales. There was a large degree of spatial heterogeneity in salinity between sub-regions of Florida Bay due to differing freshwater sources and geomorphology. Mesozooplankton abundance displayed interannual variability and a positive correlation with salinity. Both of these features were also closely correlated with abundance of the dominant planktivorous fish, Anchoa mitchilli, indicating the importance of top-down control. The hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance during periods of increased physiological stress. The interaction between mesozooplankton and A. mitchilli, along with its correlation to salinity, was further investigated through the development of a mechanistic model of the populations in Florida Bay. The model indicated predation alone was insufficient to control mesozooplankton populations; rather, it was necessary to incorporate density-dependence utilizing a logistic prey population. With both mechanisms the model was able to replicate the observed interannual variability pattern and positive correlation between mesozooplankton and salinity. A preliminary management scenario evaluation suggests a two to six-fold difference in A. mitchilli and mesozooplankton populations between targeted and general salinity reductions. This suggests alternative freshwater management scenarios could produce drastically different ecological consequences.

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 220-234).