The purpose of this work was to describe the current status of benthic communities on the main stream of Elbe River and Ohře River and their tributaries affected and non-affected by biological invasions - especially by round goby (Neogobius melanostomus) and spiny - cheek crayfish (Faxonius limosus). Sampling for this research took place from April 2018 to August 2018, while morphiologic survey of waterbodies was done in November 2017. Two tributaries of the Elbe River (Milešovský brook and Ploučnice River) and one tributary of the Ohře River (Čepel) were selected for this research. Two 100 m long sections (lower stretch potentially affected by invaders and upper stretch as referential) were monitored at each tributary. At the same time a 100 m long main flow section was monitored near the mouth of the tributaries. The following parameters were monitored: morphology of the stream and basic physical and chemical parameters of water, zoobenthos community, crayfish occurrence, and fish community. The benthic communities of the upper streams were less affected by biological invasions. The biodiversity of the benthic communities in the upper sections was richer compared to the lower sections. The occurrence of the round goby seemed to be factor affecting benthic and fish communities at the sites concerned. It was an eudominant species in the Elbe section in Děčín and becoming dominant in the lower section of Ploučnice River.

Mes objectifs consistaient à : (1) fournir une description de l'état actuel des communautés de la macrofaune benthique du golfe du Lion et à étudier leur variations temporelles entre 1998 et 2010 à partir de 91 stations, (2) tester le contrôle de la macrofaune par les variables climatiques à partir du suivi de 4 stations pendant 10 ans en baie de Banyuls-sur-Mer, (3) évaluer l’impact des apports du Rhône sur la macrofaune à partir de 5 stations échantillonnées dans le panache de dilution à 4 périodes hydrologiques différentes, et (4) actualiser le statut de qualité écologique des habitats benthiques du golfe. Mes résultats ont montré la conservation des communautés entre 1998 et 2010,confirmé l’influence de la NAO et du Rhône sur la composition des communautés benthiques de l’ensemble du golfe. Ils ont aussi confirmé le contrôle des descripteurs de la macrofaune par les oscillations climatiques, en particulier par la WeMO qui semble influencer le plus la macrofaune surtout en hiver. Les stations les plus impactées par les variations de débit du Rhône se situent à proximité immédiate de son embouchure. Les communautés benthiques y sont négativement affectées en périodes de crues et positivement affectées en période d’étiage estival. J'ai enfin mis à jour les niveaux de sensibilité/tolérances des espèces méditerranéennes, confirmer l’existence de disparités importantes entre les résultats dérivés de l’utilisation d’indices biotiques différents et montrer que les indices testés indiquent tous une tendance générale à la stabilité. / My main aims consisted in: (1) assessing the present state and recent (1998-2010)changes in benthic macrofauna composition of the Gulf of Lions soft-bottom communities through the long term comparison of 91 stations; (2) testing the current paradigm regarding the control of those communities by climatic parameters through a 10-year monitoring of 4 stations located in the Bay of Banyuls-sur-Mer; (3) assessing the influence of Rhône River inputs on the composition of benthic macrofauna through the sampling, of 5 stations , under 4 hydrological regimes; and (4) updating the ecological quality status of Gulf of Lions benthic habitats. My results have shown the persistence ofthe same 3 communities between 1998 and 2010, the strong influence of both the NAO and the Rhône River on benthic macrofauna composition in the whole Gulf. They also showed a control of benthic macrofauna by climatic oscillations with the WeMO contributing most especially during wintert ime. Moreover, the stations most impacted by Rhône River inputs were located close to its mouth. They are negatively affected during floods and positively affected during dry periods. Lastly, Ihave updated the sensitivity/tolerance levels of Mediterranean species and confirmed the existence of major discrepancies in the results derived from different biotic indices used, although all tested indices indicated an overall stability in the ecological quality status of benthic habitats between 1998 and 2010.

De la profondeursur 2 sites en Guadeloupe pendant la saison sèche et la saison humide (Chapitre 3). A u cours de cette étude,les genres Ostreopsis et Prorocentrum étaient les plus abondants. Aucune influence de la profondeur n'a é;étrouvée sur l'abondance totale des dinoflagellés benthiques ; cependant les genres Ostreopsis et GambiericLscusétaient principalement abondants en surface, alors que le genre Coolia était présent plus en profondeur.L'approche d'écologie trophique concernait le lien trophique entre dinoflagellés benthiques toxiqueset méiofaune (Chapitre 1). Les transferts au sein des réseaux trophiques de phycotoxines synthétisées par lesdinoflagellés benthiques toxiques sont généralement étudiés chez les organismes de grande taille, délaissantles organismes de μeLile Laille qui sulll pourtant en contact direct avec les microalgues. Au cours de cetteétude, une attention particulière a été portée aux copépodes harpacticoïdes qui composent ia méiofaune.Cette étude expérimentale, par marquage des microalgues aux isotopes stables, s'est focalisée sur lescopépodes harpacticoïdes et a permis de mesurer le taux d'ingestion d'Amphidinium sp. et d'Ostreopsis sp ..Cette étude démontre que les organismes de la méiofaune peuvent constituer une voie d'entrée des toxinessynthétisées par les dinoflagellés benthiques dans les réseaux trophiques. / The distribution of benthic toxiï rlinofüeefü1tes is 1111known in (Juadeloupe and Martinique even if at theCaribbean basin spatial scale, those microalgae are responsible for serious poisoning such as ciguatera.During this thesis, the ecology of benthic toxic dinoflagellates μreseul was sLudieJ using: spatio-temporalstudies (Chapters 1, 2, 3) and a trophic ecology approach (Chapter 4).First, 27 sites were explored to describe the spatial distribution of benthic dinoflagellatf's prPsf'nt inGuadeloupe and Martinique (Chapter 1). Only the most abundant macrophytes (biological substrates ofbenthic dinoflagellates) at the different sites were considered. ln this study, 161 samples were analyzed and 7times more taxie benthic dinoflagellates were found in Guadeloupe than in Martinique. The genus Ostreopsisdominated the benthic dinoflagellate community in both islands, although this trend has only rarely beenfound in the Caribbean basin.Then, 3 sites per department were chosen in order to set up a monthly monitoring of benthicdinoflagellates abundances duringl8 months (Chapter 2). The sites selected i) had a high abundance ofbenthic toxic dinoflagellates and ii) were identified as potentially dangerous by the Agence Régionale de laSanté. During this study, 927 samples of macrophytes were analyzed and 5 times more benthic toxicdinoflagellates were found in Guadeloupe than in Martinique. Ostreopsis and Prorocentrum genera dominatedrespectively in Guadeloupe and in Martinique. Two times more Gambierdiscus were found in Martinique thanin Guadeloupe even if Guadeloupe is located in the high prevalence area and this genus being responsible forciguatera. This result suggested that species with different toxicities structured the benthic toxicdinoflagellates community in this area. The abundances of benthic dinoflagellates were little influenced byabiotic parameters (temperature and salinity) but structured by biotic parameters (host macrophytes).Halophila stipulacea an invasive angiosperm in the Lesser Antilles has been identified as promoting thedevelopment of the genus Gambierdiscus.. The distribution of benthic toxic dinoflagellates was also studied according to the depth at 2 sites inGuadeloupe during the dry and the wet seasons (Chapter 3). ln order to avoid bias due to the presence ofdifferent macrophytes, this experiment was conducted only on H. stipulacea constituting mono-specificmeadows along a strong depth gradient. ln this study, the Ostreopsis and Prorocentrum genera were the mostabundant. No influence of the depth was found on total abundance of benthic dinoflagellates; however,Ostreopsis and Gambierdiscus genera were mainly abundant near the surface while the genus Coolia was presentdeeper.The trophic ecology approach focused on the trophic link between taxie benthic dinoflagellates andmeiofauna (Chapter 4). Transfers within the food webs of phycotoxins synthesized by benthic dinoflagellatesare mainly studied in large organisms neglecting smaller ones in direct contact with microalgae. Thisexperimental study, by labeling the microalgae with stable isotopes, focused on harpacticoides copepod andmeasured for the first time their ingestion rates of Amphidinium sp. and Ostreopsis sp.. This studydemonstrated that meiofauna organisms can constitute an input channel of phycotoxins from benthicdinoflagellates in food webs.

No description available.

The aim of this study was to develop and examine the use of backscatter data collected with multibeam sonar (MBS) systems for benthic habitat mapping. Backscatter data were collected from six sites around the Australian coastal zone using the Reson SeaBat 8125 MBS system operating at 455 kHz. Benthic habitats surveyed in this study included: seagrass meadows, rhodolith beds, coral reef, rock, gravel, sand, muddy sand, and mixtures of those habitats. Methods for processing MBS backscatter data were developed for the Coastal Water Habitat Mapping (CWHM) project by a team from the Centre for Marine Science and Technology (CMST). The CMST algorithm calculates the seafloor backscatter strength derived from the peak and integral (or average) intensity of backscattered signals for each beam. The seafloor backscatter strength estimated from the mean value of the integral backscatter intensity was shown in this study to provide an accurate measurement of the actual backscatter strength of the seafloor and its angular dependence. However, the seafloor backscatter strength derived from the peak intensity was found to be overestimated when the sonar insonification area is significantly smaller than the footprint of receive beams, which occurs primarily at oblique angles. The angular dependence of the mean backscatter strength showed distinct differences between hard rough substrates (such as rock and coral reef), seagrass, coarse sediments and fine sediments. The highest backscatter strength was observed not only for the hard and rough substrate, but also for marine vegetation, such as rhodolith and seagrass. The main difference in acoustic backscatter from the different habitats was the mean level, or angle-average backscatter strength. However, additional information can also be obtained from the slope of the angular dependence of backscatter strength. / It was shown that the distribution of the backscatter. The shape parameter was shown to relate to the ratio of the insonification area (which can be interpreted as an elementary scattering cell) to the footprint size rather than to the angular dependence of backscatter strength. When this ratio is less than 5, the gamma shape parameter is very similar for different habitats and is nearly linearly proportional to the ratio. Above a ratio of 5, the gamma shape parameter is not significantly dependent on the ratio and there is a noticeable difference in this parameter between different seafloor types. A new approach to producing images of backscatter properties, introduced and referred to as the angle cube method, was developed. The angle cube method uses spatial interpolation to construct a three-dimensional array of backscatter data that is a function of X-Y coordinates and the incidence angle. This allows the spatial visualisation of backscatter properties to be free from artefacts of the angular dependence and provides satisfactory estimates of the backscatter characteristics. / Using the angle-average backscatter strength and slope of the angular dependence, derived by the angle cube method, in addition to seafloor terrain parameters, habitat probability and classification maps were produced to show distributions of sand, marine vegetation (e.g. seagrass and rhodolith) and hard substrate (e.g. coral and bedrock) for five different survey areas. Ultimately, this study demonstrated that the combination of high-resolution bathymetry and backscatter strength data, as collected by MBS, is an efficient and cost-effective tool for benthic habitat mapping in costal zones.

Abstract not available

Three approaches were employed to examine the effects of elevated sediment trace metal concentrations on estuarine/marine macrobenthic invertebrate assemblages. The initial study examined macroinvertebrate communities along a known polymetallic gradient, Lake Macquarie, NSW (gradient study). The second study experimentally tested if sediments sourced from different locations within Lake Macquarie differentially influenced the recolonisation of benthic invertebrates. The third study investigated the different recolonisation patterns of benthic invertebrates into sediments spiked with increasing concentrations of sediment-bound cadmium. In the Lake Macquarie gradient study, four locations (Cockle Bay, Warner's Bay, Kooroora Bay and Nord's Wharf) were sampled in winter 2000 and summer 2003 using a hierarchical design (location > site > plot). On both sampling occasions, the sediments showed strong gradients in lead, cadmium and zinc concentrations emanating from the Cockle Bay industrialised region in the lake's north, with concentrations being significantly lower in the most southern and less urbanised location (Nord's Wharf). In general, concentrations of lead, cadmium and zinc in the sediments increased among locations in the following order: Nord's Wharf > Kooroora Bay > Warner's Bay > Cockle Bay. AVSJSEM analyses indicated that in some sites in Cockle Bay, and to a lesser extent Warner's Bay, SEM concentrations exceeded their molar equivalence of AVS, indicating the potential for trace metals to be labile within the porewaters. Granulometry also changed along the gradient, with a higher proportion of silt/clay occurring in the locations with high metal concentrations. Conversely, the percentage of total organic carbon was higher in the less contaminated locations. In winter 2000, changes in benthic communities along the gradient supported the a priori hypotheses, with diversity and richness being greater in locations with lower concentrations of metals. Polychaetes were most numerous in Cockle Bay and Warner's Bay, whilst bivalves and gastropods were more abundant in Nord's Wharf and Kooroora Bay. Crustaceans were more numerous in Nord's Wharf; with all other locations having similar, lower, abundances. Ordination maps of the assemblages provided relatively clear separation of the assemblages among locations, with nonparametric multivariate analysis of variance (NPMANOVA) and subsequent pair-wise comparisons finding significant differences among the assemblages from all locations. SIMPER analyses found the highest level of dissimilarity was between the Nord's Wharf and Cockle Bay assemblages - primarily attributable to differences in the relative contributions of isopods; tellenid bivalves; and the polychaete families Spionidae, Opheliidae and Nephytidae. Weighted Spearman rank correlations (BIOENV) identified cadmium (Pw =0.74) as the strongest environmental (single or combination) variable to correlate with biotic assemblages. Benthic patterns along the gradient were less defined in summer 2003 due to a dramatic reduction in the abundance and diversity of fauna in Nord's Wharf. This decline was possibly attributable to a sustained reduction in salinity caused by a prolonged rainfall event. With the exception of Nord's Wharf, trends in the community indices and abundances of key taxa among the other locations were similar to those reported in winter 2000. Multivariate analyses discriminated the benthic assemblages from the four locations, with the findings from the NPMANOVA pair-wise comparisons indicating that the assemblages from all four locations were significantly different. SIMPER analyses showed the highest level of dissimilarity was between Nord's Wharf and Warner's Bay, with these differences being primarily attributable to their relative abundances of amphipods and polychaetes from the families Spionidae, Cirratulidae, Opheliidae and Capitellidae. BIOENV found that the combination of the sedimentary concentrations of cadmium and iron provided the best correlation (Pw =0.73) with biotic patterns, with similar correlations occumng with the addition of lead and its covariate, zinc (Pw =0.72). The combined findings from the gradient study established a strong correlation between trace metal concentrations within the sediments and suite of univariate and multivariate measurements. The low abundance and diversity of fauna in Nord's Wharf in the summer of 2003 highlighted the dynamic changes which can occur in the distributions of macrobenthic invertebrates. Although the study indicated that there was a strong relationship between trace metal concentrations and benthic community structure, the study was correlative, and requires subsequent experimental testing to confirm the causality of the observed relationships. The second component of the research was a translocation experiment using benthic recolonisation as an end-point. The experiment was performed to identify if the sediments, and not location, were influencing the composition of benthic assemblages in Lake Macquarie. Sediments were collected from three locations (Cockle Bay, Warner's Bay and Nord's Wharf), defaunated, and transplanted in three new locations along the south-east edge of the lake. At each location, 10 containers of each treatment were randomly placed in the sediment and allowed to recolonise for 22 weeks. Upon retrieval, the benthic communities were sampled and enumerated in conjunction with a variety of chemical and sedimentary measurements. Ten replicate invertebrate samples were also collected in the sediments adjacent to the experiment (ambient samples) at the completion of the experiment. Due to human interference, the containers from only two locations were analysed. Upon retrieval, pH and redox profiles of the sediments were similar to those expected in natural sediments. In general, concentrations of metals were low in the porewaters; however, iron precipitation on the porewater collection devices may have artificially increased the diffusion of metals, increasing concentrations near the sediment-water interface. Concentrations of SEM exceeded their AVS equivalence in some samples taken from the Cockle Bay and Warner's Bay treatments. Two-way ANOVAs found significant interactions between location and sediment treatments in diversity, evenness and the number of polychaetes, as well as significant differences in the number of capitellids and crustaceans among locations. Post-hoc comparisons of means found the Nord's Wharf sediment contained a higher mean number of individuals than the other treatments, including the ambient samples. nMDS ordination plots for both locations provided poor graphical discrimination of the assemblages among treatments; however, NPMANOVA detected significant location and treatment interactions. In both locations, pair-wise comparisons indicated that the assemblages within the Nord's Wharf treatments were significantly different to the Cockle Bay, Warner's Bay and ambient assemblages. No significant differences were detected between the Cockle Bay and Warner's Bay assemblages at either location. SIMPER analyses found the highest level of dissimilarity occurred between the ambient assemblages in Location 2 and the Nord's Wharf treatment, primarily due to the relative difference in the abundances of Capitellidae, Spionidae, Oweniidae, Nereididae and isopods among the assemblages. The findings from the translocation experiment suggest that the sediments are influencing the recolonisation of benthos. However, because differences were not detected between the Cockle Bay and Warner's Bay treatments, the approach used in the study shows potential as an in situ technique which could be used to assess the potential ecological risks of sediments fiom specific locations. Excluding cost and time considerations, the technique's primary disadvantage is the lack of a true control. As a result, the technique can only identify if the sediments are modifying benthic recolonisation, and not causality. The final component of the research experimentally tested if elevated concentrations of sediment-bound cadmium affected benthic invertebrate recolonisation. Sediments from the south coast of New South Wales (Durras Lake) were defaunated, and spiked with cadmium under anaerobic conditions to obtain three targeted cadmium concentrations: control (<O.1 ug/g), Low-Cd (15 Cd ug/g) and High-Cd (150 Cd ug/g). The physio-chemical properties of the waters and porewater concentrations of cadmium were monitored over a 28-day equilibration period, with declines in pH mediated with the addition of NaOH(aq). At the end of the equilibration period, porewater concentrations of cadmium were low in the Low-Cd and High-Cd treatments (maximum <l.5 ug/L in High-Cd), and below the detection limit in the control. Cadmium was not detected in the control sediments, with concentrations in the Cd-Low and Cd-High sediments exceeding their targeted concentrations, with final mean concentrations of 17 ug/g and 183 ug/g, respectively. The experimental design was similar to that employed in the translocation experiment, with 10 containers from each treatment transplanted into the sediments at three locations within Lake Macquarie. After 20 weeks, the containers were collected, along with benthic invertebrate samples from the ambient sediments. Data was not used from Location C due to extensive sediment deposition on the transplanted treatments. Significant declines occurred in the concentrations of cadmium in both the Low-Cd and High-Cd sediments, with the greatest loss occumng in the surficial sediments. The loss of cadmium was probably due to the differential loss of the fine fraction through physical means (hydrodynamic) rather than fluxing, as it assumed that the cadmium was primarily sediment-bound and relatively insoluble under anoxic conditions. Mean porewater concentrations of cadmium were below the detection limit in the control treatments; < 1 ug/L in the Low-Cd treatment, and generally < 2ug/L in the High-Cd, with the exception of some samples in Location B (maximum 5.6 ug/L) Concentrations of ammonia were low in the porewaters from the surficial sediments, with concentrations being significantly higher, and potentially toxic, in the anoxic porewaters (7 cm depth). In comparison to the previous recolonisation experiment, the number of individuals which recolonised the cadmium-spiked treatments was low, and significantly lower than the mean number of individuals sampled in the ambient sediments. No significant differences were detected among the treatments or locations (and their interactions) in diversity (H'), richness (d) or evenness (J). The number of polychaetes and molluscs significantly differed among the treatments, with post-hoc analyses indicating these differences were not among the cadmium-spike treatments, but were due to a greater mean abundance of these taxa in the ambient sediments. A significant interaction between treatment and location was detected in the mean abundance of crustaceans, with the ambient sediments having significantly lower mean abundances in both Location A and B. Ordination plots of the experiments in Location A and B provided poor graphical discrimination among the spiked treatments, although the ambient assemblages appear to be separated from the cadmium-spiked assemblages. NPMANOVA detected a significant interaction between treatments and locations, as well as among treatments. In both Location A and B, pair-wise analyses found the assemblages in the ambient sediments to be significantly different to the assemblages in all three cadmium treatments, with no differences being detected among the latter. SIMPER analyses found the highest levels of dissimilarity occurred between the spike-treatments and the ambient sediments, with these differences being primarily due to the relatively higher abundance of decapods in the spiked treatments, and capitellids in the ambient sediments. The cadmium-spiking component of the experiment clearly illustrated that artificially increasing the trace metal concentrations of metals in estuarine sediments is a complex process which needs to be performed in a methodological manner in order to obtain homogenous treatments with low porewater concentrations, and minimal artefacts. Furthermore, the results confirmed that the equilibration time for sediments can be extensive (several weeks), even in the case of organically rich sediments. The timing of the experiment (commenced late summer, February, 2003) appears to the major factor for the relatively low recolonisation rates, with the experiment missing the main larval recolonisation period between spring and early summer. Even in the highest treatment, elevated concentrations of cadmium did not appear to affect benthic recolonisation. This finding is supported by other experimental studies which suggest that concentrations of a single isolated metal must considerably exceed current guideline values (or contain high porewater concentrations) in order to elicit a biological effect. Nevertheless, as trace metals generally co-occur with other contaminants - with the response of multiple contaminants being possibly additive or synergistic - a conservative guideline value may be suitable in the interim as a precautionary measure. The findings of this thesis suggest that elevated concentrations of trace metal mixtures in estuarine sediments can affect the structure and composition of benthic communities; however, identifying causality is difficult. Although there has been an increase in the use of manipulative field experiments as a means of reducing the confounding influence of covariables found in field studies, this approach also has limitations, e.g. spatial and temporal scale issues, container effects, cost and biogeochemical changes to the sediments. Measuring stress at a community level is a fundamental component of estuarine risk assessment programs; and in isolation this approach can produce subjective and confounded findings. In order to accurately assess the risks associated with trace metal contaminated sediments, an integrated approach (e.g. weight of evidence) is required, one which uses multiple lines of evidence sourced from various chemical, environmental biological measurements.

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish.  Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements. / At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper  2: Accepted; Paper 3: Submitted; Paper  4: Accepted

Manmade radionuclides have been introduced to the environment for almost a century. The main source has been the nuclear weapons testing programmes, but accidental releases from the nuclear power production industries have also contributed. The risk to humans from potential releases from nuclear facilities is evaluated in safety assessments. Essential components of these assessments are exposure models, which estimate the transport of radionuclides in the environment, the uptake in biota, and transfer to humans. Recently, there has been a growing concern for radiological protection of the whole environment, not only humans, and a first attempt has been to employ model approaches based on stylised environments and transfer functions to biota based exclusively on bioconcentration factors. They are generally of a non-mechanistic nature and involve no knowledge of the actual processes involved, which is a severe limitation when assessing real ecosystems. The research presented in this thesis attempts to introduce a methodology for modelling exposure of biota that is based on systems ecological theories and concepts. All presented papers concern bioaccumulation and circulation of radionuclides in coastal areas of the Baltic Sea, which is a sea surrounded by several nuclear power plants, waste repositories and reprocessing facilities. Paper I illustrates how an ecosystem model can be used to predict the fate of C-14 in a bay, and to explore the influence of uptake route and water exchange on the concentrations in biota. Due to the longevity of many radionuclides, time spans of thousands of years need to be considered in assessments of nuclear waste facilities. In Paper II, the methodological problems associated with these long timescales are discussed and a new modelling approach is proposed. An extension and generalisation of the C-14 flow model into a generic model for other radionuclides is described and tested in Paper III. This paper also explores the importance of three radionuclide specific mechanisms (plant uptake, excretion and adsorption to organic surfaces) for the concentrations in biota. In Paper IV, the bioaccumulation kinetics of three radionuclides in three key benthic species of the Baltic Sea is studied experimentally. Paper V considers remobilisation and redistribution of sediment-associated radionuclides due to biological mixing, in a microcosm study. The findings in this thesis show both that it was possible to use an ecosystem approach to assess the exposure to biota, and that this approach can handle many of the problems identified in the use of traditional exposure models for radionuclides. To conclude, frameworks for the protection of the environment from ionising radiation would benefit from implementing methodologies based on ecologically sound principles and modelling techniques.

Sediment quality guidelines (SQGs) or values (SQVs) are used to assess the potential risk of contaminants in sediment to aquatic organisms, specifically benthic invertebrates. The objectives of this research were to evaluate SQGs derived specifically for use by the uranium industry in Canada, propose alternative SQVs for use at uranium operations in northern Saskatchewan using a novel approach, and investigate the potentially bioavailable fractions of metals in sediment which could become an alternative measurement to the typically used total metal concentrations. The screening-level concentration (SLC) approach has been used in Ontario, Canada, to derive lowest effect levels (LELs) and severe effect levels for use as SQGs. This approach was adopted by the Canadian Nuclear Safety Commission (CNSC) to set guidelines for metals (As, Cr, Cu, Pb, Mo, Ni, Se, U, and V) and radionuclides (Ra-226, Pb-210, and Po-210) in sediment at northern Saskatchewan uranium mining and milling operations. The SLC approach is based on total metal and radionuclide concentrations in sediment, and corresponding benthic invertebrate community composition data for a specific sampling site. In this study, sediment chemistry (total metals and radionuclides) and benthic community data from northern Saskatchewan uranium operations were compiled and examined. Results indicated that the CNSC-derived SQGs had limited relationships to observed effects, or lack thereof, on benthic invertebrate communities near uranium operations in Saskatchewan. On a general basis, the correct alignment of at least one LEL exceedence at an effect site was observed 95% of the time, but on an element-specific basis many of the elements had concentrations at effect sites below their LELs. Furthermore, concentrations of the evaluated elements exceeded at least one LEL at 60% of the no-effect sites. The high number of exceedences of LELs at reference and no-effect sites (false-positives) calls to question the appropriateness of the CNSC-derived SQGs. To address the deficiencies of the SLC approach, a new approach was developed to derive alternative metal SQVs for the uranium industry in northern Saskatchewan that was based on the use of reference and no-effect site field data. Three different sets of NE values were derived using combinations of benthic invertebrate community effect criteria (abundance, richness, evenness, Bray-Curtis index). Additionally, reference (REF) values were derived based solely on sediment metal concentrations from reference sites. In general, NE values derived using abundance, richness, and evenness (NE1 and NE2 values) were found to be higher than the NE values derived using all four metrics (NE3 values). Derived NE values for Cr, Cu, Pb, and V did not change with the incorporation of additional effects criteria due to a lack of influence from the uranium operations on these metal concentrations (i.e., they were generally present at or near background levels). However, a gradient of exposure concentrations was apparent for As, Mo, Ni, Se, and U in sediment which allowed for acceptable exposure levels of these metals in sediment to be defined. The findings from this assessment proposed a set of new, alternate SQVs for use at the uranium industry in northern Saskatchewan. Often, only total metals concentrations are measured in the evaluation of contaminated sediment. However, this measure may over-estimate metal exposure to benthic invertebrates. Using sediment cores collected from near the Rabbit Lake and Key Lake uranium operations, along with a series of mixed-sediments (contaminated and reference sediment), metal bioaccumulation experiments using Chironomus dilutus were conducted in the laboratory. Metal concentrations in extracts from single extractions with either potassium phosphate or hydrochloric acid on wet and dried sediment, pore-water, and whole-sediment were used to evaluate metal bioaccumulation in test organisms. Depending on the metal, pore-water isolated using peepers generally exhibited the best relationship with tissue metal concentrations. Based on this finding, it is suggested that pore-water sampling using peepers (an in-situ dialysis device) be added to environmental sampling programs at Saskatchewan uranium operations so that sediment metal availability to benthic invertebrates can be better assessed. With the eventual development of a larger pore-water metals dataset, SQGs based on pore-water metals concentrations could likely be derived as an alternative to existing SQGs based on total metal concentrations in sediment.