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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Comparison of Quantitative and Semi-Quantitative Assessments of Benthic Macroinvertebrate Community Response to Elevated Salinity in central Appalachian Coalfield Streams

Pence, Rachel A. 18 January 2019 (has links)
Anthropogenic salinization of freshwater is a global concern. In freshwater environments, elevated levels of major ions, measured as total dissolved solids (TDS) or specific conductance (SC), can cause adverse effects on aquatic ecosystem structure and function. In central Appalachia, eastern USA, studies largely rely on Rapid Bioassessment Protocols with semi-quantitative sampling to characterize benthic macroinvertebrate community response to increased salinity caused by surface coal mining. These protocols require subsampling procedures and identification of fixed numbers of individuals regardless of organism density, limiting measures of community structure. Quantitative sampling involves enumeration of all individuals collected within a defined area and typically includes larger sample sizes relative to semi-quantitative sampling, allowing expanded characterization of the benthic community. Working in central Appalachia, I evaluated quantitative and semi-quantitative methods for bioassessments in headwater streams salinized by coal mining during two time periods. I compared the two sampling methods for capability to detect SC-induced changes in the macroinvertebrate community. Quantitative sampling consistently produced higher estimates of taxonomic richness than corresponding semi-quantitative samples, and differences between sampling methods were found for community composition, functional feeding group, dominance, tolerance, and habit metrics. Quantitative methods were generally stronger predictors of benthic community-metric responses to SC and were more sensitive for detecting SC-induced changes in the macroinvertebrate community. Quantitative methods are advantageous compared to semi-quantitative sampling methods when characterizing benthic macroinvertebrate community structure because they provide more complete estimates of taxonomic richness and diversity and produce metrics that are stronger predictors of community response to elevated SC. / Master of Science / Surface coal mining in central Appalachia, eastern USA, contributes to increased salinity of surface waters, causing adverse effects on water quality and aquatic life. Stream condition is often evaluated through sampling of benthic macroinvertebrates because they are ubiquitous in aquatic environments and differ in sensitivity to various types of pollution and environmental stressors. In central Appalachia, studies have largely relied on semi-quantitative sampling methods to characterize effects of elevated salinity on benthic macroinvertebrate communities in headwater streams. These methods are ‘semiquantitative’ because processing of samples requires subsampling procedures and identification of a fixed number of individuals, regardless of the number of organisms that were originally collected. In contrast, quantitative sampling involves identification and counting of all collected individuals, often resulting in organism counts that are much higher than those of semi-quantitative samples. Quantitative samples are typically more time-consuming and expensive to process but allow for expanded description of the benthic macroinvertebrate community and characterization of community-wide response to an environmental stressor such as elevated salinity. Working in central Appalachian streams, I compared 1) depictions of benthic macroinvertebrate community structure; 2) benthic community response to elevated salinity; and 3) the minimum levels of salinity associated with community change between quantitative and semi-quantitative methods. Quantitative sampling methods provide many advantages over semi-quantitative methods by providing more complete enumerations of the taxa present, thus enhancing the ability to evaluate aquatic-life condition and to characterize overall benthic macroinvertebrate community response to elevated salinity caused by surface coal mining.
2

Diverzitet, distribucija, diferencijacija mikrostaništa i struktura zajednica mahovina Fruške gore / Diversity, Distribution, Microhabitat Differentiation and Community Structure of Bryophytes of Fruška Gora Mountain

Ilić Miloš 11 June 2019 (has links)
<p>U&nbsp; radu&nbsp; je&nbsp; analizirana&nbsp; brioflora&nbsp; Fru&scaron;ke&nbsp; gore.&nbsp; Cilj istraživanja bio je&nbsp; utvrđivanje diverziteta, distribucije, uslova mikrostani&scaron;ta i strukture zajednica mahovina na&nbsp; različitim&nbsp; tipovima&nbsp; stani&scaron;ta&nbsp; na&nbsp; Fru&scaron;koj&nbsp; gori. Takođe,&nbsp; jedan&nbsp; od&nbsp; ciljeva&nbsp; je&nbsp; bio&nbsp; i&nbsp; testiranje&nbsp; i optimizacija&nbsp; metode&nbsp; za&nbsp; kvantitativna&nbsp; uzorkovanja briofita&nbsp; na&nbsp; različitim&nbsp; tipovima&nbsp; stani&scaron;ta.&nbsp; Terenska istraživanja su vr&scaron;ena u periodu 2013-2017 godine. Za<br />potrebe florističkih istraživanja terenska uzorkovanja su&nbsp; vr&scaron;ena&nbsp; metodom&nbsp; transekta&nbsp; na&nbsp; 120&nbsp; lokaliteta&nbsp; na području&nbsp; Fru&scaron;ke&nbsp; gore.&nbsp; Za&nbsp; testiranje&nbsp; i&nbsp; optimizaciju metoda&nbsp; za&nbsp; kvantitativna&nbsp; briolo&scaron;ka&nbsp; uzorkovanja kori&scaron;ćene&nbsp; su&nbsp; različite&nbsp; varijante&nbsp; metoda&nbsp; &bdquo;kvadrata&ldquo; (metod ugneždenih kvadrata za prizemnu briofloru i metod&nbsp; postavljanja&nbsp; mikroplotova&nbsp; na&nbsp; različitoj udaljenosti&nbsp; za&nbsp; epifitsku&nbsp; briofloru).&nbsp; Odgovarajuće metode&nbsp; su&nbsp; odabrane&nbsp; na&nbsp; osnovu&nbsp; kriva&nbsp; minimum areala&nbsp; i&nbsp; kriva&nbsp; sličnosti&nbsp; (eng.&nbsp; species-area&nbsp; curve, similarity&nbsp; area&nbsp; curve).&nbsp; Odgovarajuće&nbsp; metode&nbsp; su primenjene za dalja uzorkovanja u ovom istraživanju. Na pojedinim lokalitetima (&scaron;umska i livadska stani&scaron;ta) vr&scaron;eno je merenje nekoliko ekolo&scaron;kih parametara (pH zemlji&scaron;ta&nbsp; i&nbsp; kore&nbsp; drveta,&nbsp; vlažnost&nbsp; zemlji&scaron;ta, temperatura zemlji&scaron;ta, pokrovnost stelje, pokrovnost<br />zeljastih vaskularnih biljaka, udaljenost od potoka u &scaron;umskim stani&scaron;tima i udaljenost &scaron;umskih ekosistema na&nbsp; livadskim&nbsp; stani&scaron;tima)&nbsp; u&nbsp; cilju&nbsp; utvrđivanja&nbsp; uticaja merenih&nbsp; ekolo&scaron;kih&nbsp; parametara&nbsp; na&nbsp; diverzitet&nbsp; i distribuciju briofita.&nbsp; Briofitske zajednice su utvrđene na&nbsp; različitim&nbsp; tipovima&nbsp; stani&scaron;ta&nbsp; i&nbsp; podloge&nbsp; uz&nbsp; pomoć &bdquo;label&nbsp; propagating&nbsp; community&nbsp; detection&ldquo;&nbsp; analize.Rezultati&nbsp; ovog&nbsp; istraživanja&nbsp; su&nbsp; pokazali&nbsp; da&nbsp; je&nbsp; Fru&scaron;ka<br />gora područje koje se odlikuje visokim diverzitetom briofita&nbsp; i&nbsp; ukupno&nbsp; je&nbsp; zabeleženo&nbsp; 235&nbsp; briofitskih taksona (na osnovu literaturnih podataka i terenskih istraživanja).&nbsp; 73&nbsp; taksona&nbsp; briofita&nbsp; je&nbsp; prvi&nbsp; put zabeleženo&nbsp; na&nbsp; području&nbsp; Fru&scaron;ke&nbsp; gore.&nbsp; Od&nbsp; ukupnog<br />broja&nbsp; taksona,&nbsp; 11%&nbsp; je&nbsp; pod&nbsp; nekim&nbsp; stepenom ugroženosti ili zakonske za&scaron;tite. Metoda mikrocenoze se&nbsp; pokazala&nbsp; kao&nbsp; najadekvatniji&nbsp; metod&nbsp; za kvantitativna&nbsp; uzorkovanja&nbsp; prizemnih&nbsp; briofita&nbsp; (sa minimalnom adekvatnom veličinom kvadrata 0.5x0.5 m&nbsp; u&nbsp; &scaron;umskim&nbsp; odnosno&nbsp; 1x1&nbsp; m&nbsp; na&nbsp; livadskim stani&scaron;tima). Za epifitske briofite, kao najadekvatnija se&nbsp; pokazale&nbsp; metoda&nbsp; postavljanja&nbsp; mikroplotova dimenzija&nbsp; 10x10&nbsp; cm&nbsp; sa&nbsp; sve&nbsp; četiri&nbsp; strane&nbsp; stabla&nbsp; na međusobnoj udaljenosti od 20 cm. Struktura stani&scaron;ta ima&nbsp; značajno&nbsp; veći&nbsp; uticaj&nbsp; na&nbsp; diverzitet&nbsp; prizemnih briofita&nbsp; u&nbsp; &scaron;umskim&nbsp; stani&scaron;tima&nbsp; u&nbsp; odnosu&nbsp; na karakteristike&nbsp; zemlji&scaron;ta,&nbsp; dok&nbsp; je&nbsp; na&nbsp; livadskim<br />stani&scaron;tima zabeležen obrnut slučaj.&nbsp; Najveći uticaj na diverzitet epifitskih briofita ima visina na stablu kao i tip forofite. Na istraživanom području je detektovano devet&nbsp; zajednica&nbsp; u&nbsp; prizemnoj&nbsp; brioflori&nbsp; &scaron;umskih stani&scaron;ta;&nbsp; &scaron;est&nbsp; epifitskih&nbsp; zajednica;&nbsp; pet&nbsp; zajednica&nbsp; na livadskim&nbsp; stani&scaron;tima;&nbsp; četiri&nbsp; zajednice&nbsp; na&nbsp; trulim deblima&nbsp; i&nbsp; panjevima;&nbsp; 10&nbsp; zajednica&nbsp; na&nbsp; stenama&nbsp; i kamenju;&nbsp; četiri&nbsp; zajednice&nbsp; u&nbsp; potocima.&nbsp; Dobijeni rezultati&nbsp; predstavljaju&nbsp; građu&nbsp; za&nbsp; dalja&nbsp; briolo&scaron;ka istraživanja, kako floristička tako i ekolo&scaron;ka, i dopunu flore Srbije.</p> / <p>In&nbsp; this research, the bryophyte flora of Fru&scaron;ka gora Mountain was analyzed. The aim of this&nbsp; research was to determine the diversity, distribution, microhabitat conditions&nbsp; and&nbsp; community&nbsp; structure&nbsp; of&nbsp; bryophytes on different types of habitats on Fru&scaron;ka Gora. Also, one of the goals was testing and optimization of the method for&nbsp; quantitative sampling&nbsp; of bryophytes on different types of habitats. Field research was&nbsp; &nbsp; carried out&nbsp; in&nbsp; the&nbsp; period&nbsp; 2013-2017.&nbsp; For&nbsp; the&nbsp; purposes&nbsp; of floristic research, field sampling was carried out using the&nbsp; transect&nbsp; method&nbsp; at&nbsp; 120&nbsp; localities.&nbsp; Different variants of the &quot;quadrat&quot; method (method of nested quadrats&nbsp; for terrestrial bryophytes&nbsp; and the method of&nbsp; placing&nbsp; microplots&nbsp; at&nbsp; different&nbsp; distances&nbsp; for&nbsp; the epiphytic&nbsp; byphytes)&nbsp; were&nbsp; used&nbsp; for&nbsp; testing&nbsp; and optimization of methods for quantitative&nbsp; bryophyte sampling. Appropriate methods were selected on the basis&nbsp; species-area&nbsp; curve&nbsp; and&nbsp; similarity-area&nbsp; curve. Appropriate&nbsp; methods&nbsp; have&nbsp; been&nbsp; applied&nbsp; to&nbsp; further sampling in this study. On some localities (forest and meadow habitats) several&nbsp; environmental parameters (pH&nbsp; of&nbsp; soil&nbsp; and&nbsp; bark&nbsp; of&nbsp; wood,&nbsp; soil&nbsp; moisture,&nbsp; soil temperature,&nbsp; roof&nbsp; cover,&nbsp; coverage&nbsp; of&nbsp; herbaceous vascular&nbsp; plants,&nbsp; distance&nbsp; from&nbsp; the&nbsp; stream&nbsp; in&nbsp; forest habitats&nbsp; and&nbsp; distance&nbsp; of&nbsp; forest&nbsp; ecosystems&nbsp; in meadow&nbsp; habitats)&nbsp; were&nbsp; measured&nbsp; in&nbsp; order&nbsp; to determine their&nbsp; impact&nbsp; on&nbsp; the&nbsp; diversity&nbsp; and distribution&nbsp; of&nbsp; bryophytes.&nbsp; Bryophyte&nbsp; communities were&nbsp; identified&nbsp; on&nbsp; different&nbsp; substrates&nbsp; and&nbsp; habitat types&nbsp; using&nbsp; &quot;label&nbsp; propagating&nbsp; community detection&quot;&nbsp; analysis.&nbsp; The&nbsp; results&nbsp; of&nbsp; this&nbsp; study&nbsp; have shown that Fru&scaron;ka gora is an area characterized by a high&nbsp; diversity&nbsp; of&nbsp; bryophytes&nbsp; and&nbsp; a&nbsp; total&nbsp; number&nbsp; of 235 taxa&nbsp; were recorded (based on literature data and field&nbsp; research).&nbsp; 73&nbsp; taxa&nbsp; were&nbsp; recorded&nbsp; for&nbsp; the&nbsp; first time on this area. Of the total number of taxa, 11% is threatened&nbsp; or&nbsp; under&nbsp; legislative&nbsp; protection.&nbsp; The microcenose&nbsp; method&nbsp; proved&nbsp; to&nbsp; be&nbsp; the&nbsp; most adequate&nbsp; for&nbsp; quantitative&nbsp; sampling&nbsp; of&nbsp; terrestrial bryophytes (with a minimum quadrat size of&nbsp; 0.5x0.5 m in forests and 1x1 m in meadow habitats). For the epiphytic&nbsp; bryophytes,&nbsp; the&nbsp; method&nbsp; of&nbsp; placing&nbsp; the microplots (10x10 cm) on all four sides of the tree at a&nbsp; distance&nbsp; of&nbsp; 20&nbsp; cm&nbsp; is&nbsp; most&nbsp; suitable.&nbsp; The&nbsp; stand structure&nbsp; has a significantly greater influence on the diversity of terrestrial&nbsp; bryophytes&nbsp; in&nbsp; forest&nbsp; habitats compared&nbsp; to&nbsp; soil&nbsp;&nbsp; haracteristics,&nbsp; while&nbsp; in&nbsp; the meadow&nbsp; habitats&nbsp; there&nbsp; is&nbsp; a&nbsp; reverse&nbsp; case.&nbsp; The greatest&nbsp; influence&nbsp; on&nbsp; the&nbsp; diversity&nbsp; of&nbsp; epiphytic bryophytes has height on the tree as well as the type of&nbsp; phorphyte.&nbsp; In&nbsp; the&nbsp; investigated&nbsp; area,&nbsp; nine bryophyte&nbsp; communities&nbsp; were&nbsp; detected&nbsp; in&nbsp; ground bryopyhte&nbsp; flora&nbsp; of&nbsp; forest&nbsp; habitats;&nbsp; six&nbsp; epiphytic communities; five communities in meadow habitats; four&nbsp; communities&nbsp; on&nbsp; rotten&nbsp; trunks&nbsp; and&nbsp; horns;&nbsp; 10 communities&nbsp; on&nbsp; the&nbsp; rocks&nbsp; and&nbsp; stones;&nbsp; four communities&nbsp; in&nbsp; streams.&nbsp; The&nbsp; obtained&nbsp; results represent the&nbsp; base&nbsp; for&nbsp; further&nbsp; bryological&nbsp; research, both floristic and ecological, and the addition&nbsp; to the flora of Serbia.</p>
3

Benthic macroinvertebrate community structure responses to multiple stressors in mining-influenced streams of central Appalachia USA

Drover, Damion R. 25 June 2018 (has links)
Headwaters are crucial linkages between upland ecosystems and navigable waterways, serving as important sources of water, sediment, energy, nutrients and invertebrate prey for downstream ecosystems. Surface coal mining in central Appalachia impacts headwaters by burying streams and introducing pollutants to remaining streams including excessive sediments, trace elements, and salinity. Benthic macroinvertebrates are widely used as indicators of biological conditions of streams and are frequently sampled using semi-quantitative methods that preclude calculations of areal densities. Studies of central Appalachian mining impacts in non-acidic streams often focus on biotic effects of salinity, but other types of pollution and habitat alteration can potentially affect benthic macroinvertebrate community (BMC) structure and perhaps related functions of headwater streams. Objectives were: 1) use quantitative sampling and enumeration to determine how density, richness, and composition of BMCs in non-acidic central Appalachian headwaters respond to elevated salinity caused by coal surface mining, and 2) determine if BMC structural differences among study streams may be attributed to habitat and water-quality effects in addition to elevated salinity. I analyzed BMC structure, specific conductance (SC, surrogate measure of salinity), and habitat-feature data collected from 15 streams, each visited multiple times during 2013-2014. BMC structure changed across seasonal samples. Total benthic macroinvertebrate densities did not appear to be impacted by SC during any months, but reduced densities of SC-sensitive taxa were offset by increased densities of SC-tolerant taxa in high-SC streams. Total richness also declined with increasing SC, whereas BMCs in high-SC streams were simplified and dominated by a few SC-tolerant taxa. Taxonomic replacement was detected in high-SC streams for groups of benthic macroinvertebrates that did not exhibit density or richness response, showing that taxonomic replacement could be a valuable tool for detecting BMC changes that are not evident from analyses using conventional metrics. Specific conductance, water-column selenium concentration, large-cobble-to-fines ratio of stream substrate, and relative bed stability were associated with changes in BMC structure. These results suggest multiple stressors are influencing BMCs in mining-influenced Appalachian streams. These findings can inform future management of headwater streams influenced by mining in central Appalachia. / Ph. D. / Humans rely on headwater streams to provide water of sufficient quantity and quality for use in fishing, swimming, and other designated purposes. In central Appalachia USA, surface coal mining impacts headwaters by burying streams and introducing various types of pollutants to remaining streams. Benthic macroinvertebrates, primarily stream insects, are widely used as indicators of stream-water quality because responses by certain groups of benthic macroinvertebrates to types and levels of pollution are known. Studies of central Appalachian coal mining impacts in non-acidic streams often focus on the effects of elevated salinity on benthic macroinvertebrate community (BMC) structure; however, other types of pollution and habitat alteration can also potentially affect BMC structure. Study objectives were to determine how BMCs in central Appalachian headwaters responded to elevated salinity caused by coal surface mining, and to determine if BMC structure differences among study streams may be caused by habitat and water-quality effects other than elevated salinity. I analyzed BMC, salinity, and habitat data collected from 15 streams, each visited up to six times during 2013-2014. I found that BMC structures varied seasonally, likely caused by natural life cycle variation of benthic macroinvertebrates. Streams in watersheds impacted by more areal coal mining disturbance tended to have higher levels of salinity, water selenium concentrations, and fine sediments, and fewer types of benthic macroinvertebrates although total BMC densities were comparable to those in less-disturbed streams. The study revealed that BMCs in mining-influenced streams were less diverse and were likely functioning less effectively than BMCs in forested reference streams. Also, the measurement and analysis methods used to characterize BMC structural responses to pollution influence assessments of stream condition. Understanding the responses of benthic macroinvertebrate structure to changes in habitat and water quality in mining-influenced streams can inform future stream management efforts.

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