Although climate change is a global phenomenon, the Arctic is warming faster than any other region on earth. These climatic changes have driven rapid regional changes over the past half-century in both the physical landscape and the ecosystems therein. One such ecological interaction is between migratory shorebird survival and local insect emergence. Annually, tens of millions of migratory shorebirds travel to the Arctic to rear their young in the relative absence of predators, but in a relative abundance of food (insects). Over evolutionary time, these trophic levels have coupled: shorebird chicks tend to hatch during the period of highest terrestrial insect availability. However, climate change is currently uncoupling this food-web synchrony, creating potential for trophic mismatch. In the High Arctic near Utqiaġvik (formerly Barrow), Alaska, trophic mismatch between nesting shorebirds and their insect food base is already detectable. In this ecosystem, flies in the Family Chironomidae (non-biting midges) dominate the prey trophic level in the avian food web. We have found that the pre-emergence development of one particular midge, Trichotanypus alaskensis, defies conventional wisdom of the Family, as this species molts to an additional fifth larval instar prior to pupation and emergence (all other chironomids are known to have four larval instars). We discovered an Utqiaġvik midge that reproduces asexually, a species that was not documented in the 1970s. Utilizing controlled temperature rearings of Utqiaġvik midge larvae, we discovered that as temperatures rise, emerging chironomid adults are generally smaller in size. We have found that chironomid pre-emergence developmental rates follow a positive exponential relationship as temperatures increase, can vary by taxon, yet are consistent across field and lab settings for a given taxon. At Utqiaġvik in the 2010s, chironomid emergence occurs 8-12 days earlier than it did in the 1970s. These findings shape our understanding of trophic mismatch in this arctic food web. / Arctic Landscape Conservation Cooperative; NDSU Graduate School Dissertation Fellowship; U.S. National Fish and Wildlife Foundation; Environmental and Conservation Sciences Program; Department of Biological Sciences

The ecological role of chironomids has been described as an abundant and ubiquitous prey item for not only aquatic species, but terrestrial and avian species as well. Global use of pesticides in urban and agricultural applications have introduced a potential threat not only to chironomid populations, but to the individuals that prey on chironomids. Chironomids direct contact with the sediment has resulted in both legacy and current-use pesticides being detected in the individuals throughout their life cycle. The capacity for contaminant uptake and biotransformation among each midge life stage and from larvae to adults, however, is poorly understood. The lipophilic compounds of focus for this thesis include bifenthrin, and p,p’-DDT, along with the biotransformation products, TFP acid, BP alcohol, BP acid, p,p’-DDE and p,p’- DDD. To observe bioaccumulation and biotransformation at each life stage (2nd,3rd,4th, pupae, and adult), month long exposures were run with a subset of individuals being removed at each life stage and processed to quantify total, parent, and biotransformation product concentrations. Exposures at low concentrations (below literature C. dilutus no observable adverse effects concentration) at 25°C produced mean C. dilutus total pesticide concentrations ranging from 36.31 to 896.1 μg/kg dw lipid for bifenthrin and from 41.64 to 877.7 μg/kg dw lipid for DDT through all life stages. The 3rd instar contained the highest parent bifenthrin concentration, though this concentration was not statistically different from the concentration in the pupae. The 3rd instar also contained the highest parent concentration of DDT, though concentrations were not statistically different from concentrations in 2nd to 3rd instar larvae. C. dilutus also displayed subsequent biotransformation of DDT to DDE in each instar. By the 4th instar, 87.10% of the total concentration in the midges was DDE and DDD. The biotransformation of DDT to DDD was also observed to occur in sediments and was likely due to direct reductive dechlorination through chemical processes. Chironomid uptake of DDD increased as the parent DDT was degraded to DDD in the sediments over the testing period. This study provides a greater understanding of the bioaccumulation and biotransformation potential in chironomids at each life stage. Initial spiking concentrations were too low, resulting in low body residues and with no method detection limit or reporting limit defined for the study, so these lower measures have limited certainty. Therefore, the implications of this thesis are limited.

O bisfenol A (BPA) e o nonilfenol (NP), presentes em detergentes, pesticidas, plásticos e resinas, são conhecidos como Endocrine Disrupting-Chemicals (EDCs), Disruptores ou Desreguladores Endócrinos (DE) ou ainda Perturbadores Endócrinos ou Interferentes Endócrinos. O desregulador endócrino pode ser definido como uma substância química exógena ou mistura, que promove alterações em uma ou mais funções do sistema endócrino e na sua estrutura, causando, conseqüentemente, efeitos adversos na saúde de um organismo, ou a sua descendência. Esses compostos estão presentes nas águas de abastecimento, nos efluentes domésticos e industriais. Os desreguladores endócrinos têm ação mimética aos hormônios tanto no sítio de ligação quanto nos efeitos provocados nos seres vivos a eles expostos. Os compostos bisfenol A e nonilfenol foram identificados como desreguladores endócrinos em inúmeros trabalhos em diversos países, porém sendo pouco os efeitos em organismos tropicais. Este estudo teve como objetivo avaliar a toxicidade aguda do bisfenol A e do nonilfenol para Daphnia similis e Ceriodaphnia silvestrii, bem como, a toxicidade crônica para Ceriodaphnia silvestrii e Chironomus xanthus. Nos testes de toxicidade aguda com BPA os valores de CE(I)50; 48h foram de 10,64 mg/L para Daphnia similis e 19,9 mg/L para Ceriodaphnia silvestrii. Nos testes crônicos o valor do CEO obtido para Ceriodaphnia silvestrii foi 1,29 mg/L e para Chironomus xanthus 12 mg/L e o CENO 6 mg/L. Nos testes de toxicidade aguda feitos com NP, os valores de CE(I)50; 48h foram de 0,309 mg/L para Daphnia similis, 0,4520 mg/Lpara Ceriodaphnia silvestrii com solvente água e 0,0541 mg/L com solvente etanol, e 0,03398 mg/L para Ceriodaphnia dubia. O valor do CEO para Ceriodaphnia silvestrii foi 0,0198 mg/L e para Chironomus xanthus foi 100 \'mü\'g/g, com CENO de 50 \'mü\'g/g. Apesar das concentrações encontradas nos testes serem maiores que as encontradas nos estudos que quantificaram esses compostos no ambiente, outros estudos demonstraram que, mesmo em concentrações inferiores as obtidas nesse estudo já ocorrem problemas relacionados com o tempo da muda e com a androgenização do metabolismo de cladóceros. Além disso, a partir dos resultados obtidos com estes testes, pretende-se alertar o poder público sobre os riscos inerentes da presença destes produtos químicos nas águas e da urgência em se adotar novas técnicas no tratamento de efluentes visando à remoção eficaz desses poluentes. / Bisphenol A (BPA) and nonylphenol (NP), present in detergents, pesticides, plastics and resins, are known as Endocrine-Disrupting Chemicals (EDCs), Disruptors or Endocrine Disruptors (ED), Endocrine Disruption or Interferences Endocrine. The endocrine disruptors can be defined as an exogenous chemical substance or mixture, which causes changes in one or more functions of the endocrine system and its structure, causing, therefore, adverse effects on the health of an organism, or its progeny. These compounds are present in the water supply in domestic and industrial effluents. EDs have mimetic action to hormones in both binding site as the effects caused in living beings exposed to them. The compounds bisphenol A and nonylphenol were identified as endocrine disruptors in numerous studies in many countries, but with little effects on tropical organisms. This study aimed to evaluate the acute toxicity of bisphenol A and nonylphenol Daphnia similis and Ceriodaphnia silvestrii, as well as chronic toxicity to Ceriodaphnia silvestrii and Chironomus xanthus. In acute toxicity tests with BPA values EC(I) 50, 48 h were 10.64 mg/L for Daphnia similis and 19.9 mg/L for Ceriodaphnia silvestrii; chronic In the tests the value obtained for the CEO Ceriodaphnia silvestrii was 1.29 mg/L and 12 mg/L Chironomus xanthus CENO and 6 mg/L. In acute toxicity tests made with NP values EC(I) 50; 48h were 0.309 mg/L for Daphnia similis, 0.4520 mg/L for Ceriodaphnia silvestrii solvent and water with 0.0541 mg/L ethanol solvent and 0.03398 mg/L for Ceriodaphnia dubia. The value of the CEO to Ceriodaphnia silvestrii was 0.0198 mg/L and Chironomus xanthus was 100 \'mü\'g/g, with CENO was 50 \'mü\'g/g. Although the found concentrations in the tests are higher than those found in studies to have quantified these compounds in the environment, other studies showed that at concentrations lower than those obtained in this study have problems occur with time and the change of the metabolism of Cladocera androgenization. Also, based on the results obtained with these tests, is intended to alert the public on the risks associated of the presence of these chemicals in the water and the urgency in adopting new techniques in wastewater treatment aiming at the effective removal of these pollutants in water and in the sediment.

O bisfenol A (BPA) e o nonilfenol (NP), presentes em detergentes, pesticidas, plásticos e resinas, são conhecidos como Endocrine Disrupting-Chemicals (EDCs), Disruptores ou Desreguladores Endócrinos (DE) ou ainda Perturbadores Endócrinos ou Interferentes Endócrinos. O desregulador endócrino pode ser definido como uma substância química exógena ou mistura, que promove alterações em uma ou mais funções do sistema endócrino e na sua estrutura, causando, conseqüentemente, efeitos adversos na saúde de um organismo, ou a sua descendência. Esses compostos estão presentes nas águas de abastecimento, nos efluentes domésticos e industriais. Os desreguladores endócrinos têm ação mimética aos hormônios tanto no sítio de ligação quanto nos efeitos provocados nos seres vivos a eles expostos. Os compostos bisfenol A e nonilfenol foram identificados como desreguladores endócrinos em inúmeros trabalhos em diversos países, porém sendo pouco os efeitos em organismos tropicais. Este estudo teve como objetivo avaliar a toxicidade aguda do bisfenol A e do nonilfenol para Daphnia similis e Ceriodaphnia silvestrii, bem como, a toxicidade crônica para Ceriodaphnia silvestrii e Chironomus xanthus. Nos testes de toxicidade aguda com BPA os valores de CE(I)50; 48h foram de 10,64 mg/L para Daphnia similis e 19,9 mg/L para Ceriodaphnia silvestrii. Nos testes crônicos o valor do CEO obtido para Ceriodaphnia silvestrii foi 1,29 mg/L e para Chironomus xanthus 12 mg/L e o CENO 6 mg/L. Nos testes de toxicidade aguda feitos com NP, os valores de CE(I)50; 48h foram de 0,309 mg/L para Daphnia similis, 0,4520 mg/Lpara Ceriodaphnia silvestrii com solvente água e 0,0541 mg/L com solvente etanol, e 0,03398 mg/L para Ceriodaphnia dubia. O valor do CEO para Ceriodaphnia silvestrii foi 0,0198 mg/L e para Chironomus xanthus foi 100 \'mü\'g/g, com CENO de 50 \'mü\'g/g. Apesar das concentrações encontradas nos testes serem maiores que as encontradas nos estudos que quantificaram esses compostos no ambiente, outros estudos demonstraram que, mesmo em concentrações inferiores as obtidas nesse estudo já ocorrem problemas relacionados com o tempo da muda e com a androgenização do metabolismo de cladóceros. Além disso, a partir dos resultados obtidos com estes testes, pretende-se alertar o poder público sobre os riscos inerentes da presença destes produtos químicos nas águas e da urgência em se adotar novas técnicas no tratamento de efluentes visando à remoção eficaz desses poluentes. / Bisphenol A (BPA) and nonylphenol (NP), present in detergents, pesticides, plastics and resins, are known as Endocrine-Disrupting Chemicals (EDCs), Disruptors or Endocrine Disruptors (ED), Endocrine Disruption or Interferences Endocrine. The endocrine disruptors can be defined as an exogenous chemical substance or mixture, which causes changes in one or more functions of the endocrine system and its structure, causing, therefore, adverse effects on the health of an organism, or its progeny. These compounds are present in the water supply in domestic and industrial effluents. EDs have mimetic action to hormones in both binding site as the effects caused in living beings exposed to them. The compounds bisphenol A and nonylphenol were identified as endocrine disruptors in numerous studies in many countries, but with little effects on tropical organisms. This study aimed to evaluate the acute toxicity of bisphenol A and nonylphenol Daphnia similis and Ceriodaphnia silvestrii, as well as chronic toxicity to Ceriodaphnia silvestrii and Chironomus xanthus. In acute toxicity tests with BPA values EC(I) 50, 48 h were 10.64 mg/L for Daphnia similis and 19.9 mg/L for Ceriodaphnia silvestrii; chronic In the tests the value obtained for the CEO Ceriodaphnia silvestrii was 1.29 mg/L and 12 mg/L Chironomus xanthus CENO and 6 mg/L. In acute toxicity tests made with NP values EC(I) 50; 48h were 0.309 mg/L for Daphnia similis, 0.4520 mg/L for Ceriodaphnia silvestrii solvent and water with 0.0541 mg/L ethanol solvent and 0.03398 mg/L for Ceriodaphnia dubia. The value of the CEO to Ceriodaphnia silvestrii was 0.0198 mg/L and Chironomus xanthus was 100 \'mü\'g/g, with CENO was 50 \'mü\'g/g. Although the found concentrations in the tests are higher than those found in studies to have quantified these compounds in the environment, other studies showed that at concentrations lower than those obtained in this study have problems occur with time and the change of the metabolism of Cladocera androgenization. Also, based on the results obtained with these tests, is intended to alert the public on the risks associated of the presence of these chemicals in the water and the urgency in adopting new techniques in wastewater treatment aiming at the effective removal of these pollutants in water and in the sediment.

No description available.

This thesis resulted in the development of robust chironomid-based transfer-functions for February mean air temperature and the concentration of total nitrogen (TN) in lake-water. The New Zealand transfer-functions for both variables compare favourably with chironomid-based transfer-functions for equivalent variables from elsewhere in the world, and diatom-based transfer-functions for nutrients and lake production from New Zealand. The application of the temperature and TN transfer-functions provided insight into New Zealand climate conditions during the last glacial and served as validation for the reconstructions. Chironomid-based Temperature reconstructions from lake silts preserved in the banks of Lyndon Stream indicate a maximum cooling of ca 4 ℃ between 26.6 and 24.5 ka BP, which is consistent with estimates based on beetles and plant macrofossils. A cooling of 4 ℃ is insufficient to explain the lack of canopy tree pollen in many New Zealand pollen records at this time. Other environmental parameters additional to temperature may have limited the expansion forest cover. The chironomid-based TN reconstructions infer a trend of rapidly deteriorating water-quality in a small doline in north-west Nelson, in the South Island of New Zealand following deforestation immediately surrounding the lake ca. 1970 AD. The overall trend and timing of eutrophication inferred from the chironomids was consistent with other biological proxies and actual observations of changes in lake water quality. The chironomid-based transfer-functions provide a valuable new tool for the study of longterm climate variability and improving our understanding of the response of aquatic ecosystems to long-term natural and human induced environmental change in New Zealand lakes. I have identified some possibilities for future research which should improve the performance of these transfer-functions. The improvement of the chironomid taxonomy and the expansion of the training set should be the highest priorities.

What lurks preserved beneath lake bottoms is giving Ian R. Walker clues on how climate may change in the future.

This thesis resulted in the development of robust chironomid-based transfer-functions for February mean air temperature and the concentration of total nitrogen (TN) in lake-water. The New Zealand transfer-functions for both variables compare favourably with chironomid-based transfer-functions for equivalent variables from elsewhere in the world, and diatom-based transfer-functions for nutrients and lake production from New Zealand. The application of the temperature and TN transfer-functions provided insight into New Zealand climate conditions during the last glacial and served as validation for the reconstructions. Chironomid-based Temperature reconstructions from lake silts preserved in the banks of Lyndon Stream indicate a maximum cooling of ca 4 ℃ between 26.6 and 24.5 ka BP, which is consistent with estimates based on beetles and plant macrofossils. A cooling of 4 ℃ is insufficient to explain the lack of canopy tree pollen in many New Zealand pollen records at this time. Other environmental parameters additional to temperature may have limited the expansion forest cover. The chironomid-based TN reconstructions infer a trend of rapidly deteriorating water-quality in a small doline in north-west Nelson, in the South Island of New Zealand following deforestation immediately surrounding the lake ca. 1970 AD. The overall trend and timing of eutrophication inferred from the chironomids was consistent with other biological proxies and actual observations of changes in lake water quality. The chironomid-based transfer-functions provide a valuable new tool for the study of longterm climate variability and improving our understanding of the response of aquatic ecosystems to long-term natural and human induced environmental change in New Zealand lakes. I have identified some possibilities for future research which should improve the performance of these transfer-functions. The improvement of the chironomid taxonomy and the expansion of the training set should be the highest priorities.

Agriculture has diminished shorebirds’ natural habitat in the Mississippi Alluvial Valley. Remaining natural stopover sites are supplemented with agricultural fields during the fall and winter. This study evaluates the impact of 4 different post-harvest water management strategies on shorebird food abundance and potential agrochemical biomagnification. Chironomid samples estimated abundance, biomass, and chironomid agrochemical concentration in each field. A risk assessment of agrochemical biomagnification to shorebirds was made across all treatments. Of treatments represented on all study sites, winter treatment had greatest chironomid abundance and biomass. Models indicated that days since flood initiation, start date, and temperature are significant predictors of chironomid abundance and biomass. Risk assessment results indicate low risk to shorebirds across all treatments for agrochemicals measured in this study. This study shows that flood timing is more important to providing shorebird resources than trends in abundance and biomass of chironomids, and shorebird risk from agrochemicals measured was minimal.

No description available.