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.

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.

No description available.

The objectives of this study are to investigate the biodiversity in different unit of treatment systems, and to detect the function in a salt water type of constructed wetland. We investigated the benthic invertebrate community in different stage from 2010 July to 2011 May, while the parameters of TKN, NH3-N, organic nitrogen, TP, TOC and particle size were measured in the sediments of each sampling site at the same time in the wetland system. The results show that concentrations of organic matter and nutrients in the sediments were increased with time monthly. In May of 2010, the concentration of NH3-N were found the highest one(ANOVA, p<0.05). The particle size in sampling site 1 were the highest (ANOVA, p<0.05), while in November of 2010 all sampling sites were found exhibiting significantly different with other months (ANOVA, p<0.05). Further more, for the diversity of benthic invertebrate, we found that the parameter of the temperature was strongly negatively related to the species diversity, species abundance and species evenness, respectively (r=-387[H¡¦]¡F-533[d]¡F-438[J¡¦] ). The species diversity was increased with organic nitrogen concentrations in the sediments (r=0.492[TKN]¡F0.408[NH3-N]¡F0.493[org-N]), and were negatively related to the parameters of DO and particle size(r=-0.402[Particle size]¡F-0.287[DO] ). In addition, PCA shows that the parameters of particle size¡Borg-N¡BNH3-N¡BTKN and TOC were all important factors. Generally, it was concluded that the constructed systems, which is functioned of wetland was wastewater treatment mainly, exhibit no significant function in biodiversity.

<p>The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.</p>

The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.

No description available.

No description available.

No description available.

L'objectif de cette étude est de mieux comprendre comment la biodiversité influence le service de purification de la qualité de l'eau en tant que service de régulation capable de limiter la charge en polluants de l'eau naturelle. Peu d'études ont regardé comment les invertébrés (macro- et méio-faune) sont capables d'influencer le fonctionnement de la zone hyporhéique considérée, comme un réacteur biogéochimique contribuant largement au recyclage des nutriments. L'élimination du nitrate et la dénitrification sont utilisés comme indicateur de ce service dans les rivières afin de pouvoir suivre son évolution spatiale et temporelle. Dans cette thèse, la relation fonctionnelle entre le taux de réduction des nitrates et les organismes participant à l'expression de ce service est testée à différentes échelles d'étude allant du microcosme jusqu'à l'habitat hyporhéique d'un méandre de large rivière, la Garonne. Cette relation est mise en évidence dans une série de colonnes d'infiltration reproduisant le lit de rivière avec sa communauté benthique (projet Inbioprocess). Dans cette expérience, un gradient de biodiversité a été créé avec des combinaisons de communautés +/- biofilm, +/- méiofaune et +/- macrofaune pour tester leur influence sur l'élimination du nitrate avec et sans pesticides dans le cadre du projet Inbioprocess. Les résultats suggèrent l'influence des interactions entre communautés, sur le taux de réduction des nitrates qui est supérieur quand les invertébrés sont présents (11.8 ± 1.2) par comparaison avec les conditions sans invertébrés (7.7 ± 1.4 mg N l-1d-1 ; moyenne ± erreur standard (m ± ET)). Ces interactions ont également été suggérées comme favorisant le retour de la capacité de réduction des nitrates en présence de pesticides, utilisé comme source de stress, dans l'eau des microcosmes. Ces résultats de laboratoire montrent l'influence des interactions trophiques et non trophiques entre les différents niveaux trophiques de ce réseau, avec probablement l'implication des espèces les plus résistantes pour expliquer la capacité potentielle de résilience du système. L'existence de cette relation fonctionnelle de type "top-down" a ensuite été explorée en conditions in situ. Les taux de rétention mesurés dans 9 cours d'eau européens (projet STREAMES) ont été estimés à l'échelle du tronçon de rivière à 1.64 ± 2.39 (m ± ET) mg NO3--N m-2.min-1. L'influence des communautés d'invertébrés sur le taux de réduction des nitrates se révèle statistiquement comme aussi importante que celle des facteurs physicochimiques dans l'ensemble des tronçons explorés. L'étude des traits biologiques des communautés d'invertébrés a permis de préciser le type de communauté le plus corrélé aux processus d'élimination des nitrates. Ces organismes sont majoritairement interstitiels vivant dans les sédiments grossiers et avec des modes d'alimentation de type brouteurs de biofilm. Dans la zone hyporhéique de la zone humide alluviale de Monbéqui (projet Attenagua), la corrélation positive de la communauté d'invertébrés avec le taux de dénitrification a été seulement visible pendant automne. Cette période est considérée comme un moment propice pour l'observation de la relation diversité-fonction dans ce milieu. / This PhD study aims to understand how the biodiversity influences the water purification processes in the hyporheic zone of running water, as an important regulating service that reduces the quantity of pollutants in freshwater ecosystems. Few studies have focused on how the invertebrate community influences the functioning of hyporheic zones, which are considered as a biogeochemical reactor that largely contributes to nutrient cycling capacity of the rivers. Nitrate retention or denitrification functions in hyporheic zones are used as indicators for the water purification service. The relationship between the nitrate removal function and its associated biodiversity was tested at different scales from indoor microcosms to in-stream reaches and the hyporheic habitat of a large river (Garonne) meander, under natural and stressful conditions. First, the linkage between invertebrates and the nitrate (NO3-) removal function was given in evidence in a series of infiltration columns that mimicked the riverbed conditions with its benthic communities. A gradient of community diversity was created with biofilm, meiofauna and macrofauna communities' combination in different treatments. It enabled to test the influence of the invertebrate community on the NO3- removal rates with and without pesticides during the Inbioprocess project. The results implied the influence of invertebrate and microbial cross-community interactions on NO3- removal rates, which was higher with invertebrate communities in the sediments (11.8 ± 1.2) than without (7.7 ± 1.4 mg N.l-1.d-1). These findings suggested a top-down control of invertebrates on the microbial activities. These interactions were also depicted at the source of the recovery of the NO3- removal capacity when facing stressful conditions due to addition of pesticide in the experimental water. These laboratory findings highlighted the importance of multi-trophic level interactions in the hyporheic habitat, with probable implication of the more resistant species in the resilience capacity of this system. The occurrence of the top-down linkage was then explored in in situ habitats. The NO3- removal rates measured at the reach scale in 9 European streams during the STREAMES project ranged from 0.04 to 10.75 with an average of 1.64 ± 2.39 mg NO3--N m-2.min-1 (Mean ± SE). The results suggested that not only physico-chemical and hydrological factors, but also macro-invertebrate assemblages may influence nitrate removal. Some functional groups positively correlated with nitrate reduction were biofilm grazers and interstitial organisms associated with macro-porous substrate. In the hyporheic water of Monbequi meander of the Garonne river, the positive correlation between invertebrate diversity and the potential denitrification rates was only visible during the autumn season, suggesting a potential "hot moment" for the observation of this correlation between biodiversity and ecosystem function in fields.