1 |
Comparison of Quantitative and Semi-Quantitative Assessments of Benthic Macroinvertebrate Community Response to Elevated Salinity in central Appalachian Coalfield StreamsPence, 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 MountainIlić Miloš 11 June 2019 (has links)
<p>U radu je analizirana brioflora Fruške gore. Cilj istraživanja bio je utvrđivanje diverziteta, distribucije, uslova mikrostaništa i strukture zajednica mahovina na različitim tipovima staništa na Fruškoj gori. Takođe, jedan od ciljeva je bio i testiranje i optimizacija metode za kvantitativna uzorkovanja briofita na različitim tipovima staništa. Terenska istraživanja su vršena u periodu 2013-2017 godine. Za<br />potrebe florističkih istraživanja terenska uzorkovanja su vršena metodom transekta na 120 lokaliteta na području Fruške gore. Za testiranje i optimizaciju metoda za kvantitativna briološka uzorkovanja korišćene su različite varijante metoda „kvadrata“ (metod ugneždenih kvadrata za prizemnu briofloru i metod postavljanja mikroplotova na različitoj udaljenosti za epifitsku briofloru). Odgovarajuće metode su odabrane na osnovu kriva minimum areala i kriva sličnosti (eng. species-area curve, similarity area curve). Odgovarajuće metode su primenjene za dalja uzorkovanja u ovom istraživanju. Na pojedinim lokalitetima (šumska i livadska staništa) vršeno je merenje nekoliko ekoloških parametara (pH zemljišta i kore drveta, vlažnost zemljišta, temperatura zemljišta, pokrovnost stelje, pokrovnost<br />zeljastih vaskularnih biljaka, udaljenost od potoka u šumskim staništima i udaljenost šumskih ekosistema na livadskim staništima) u cilju utvrđivanja uticaja merenih ekoloških parametara na diverzitet i distribuciju briofita. Briofitske zajednice su utvrđene na različitim tipovima staništa i podloge uz pomoć „label propagating community detection“ analize.Rezultati ovog istraživanja su pokazali da je Fruška<br />gora područje koje se odlikuje visokim diverzitetom briofita i ukupno je zabeleženo 235 briofitskih taksona (na osnovu literaturnih podataka i terenskih istraživanja). 73 taksona briofita je prvi put zabeleženo na području Fruške gore. Od ukupnog<br />broja taksona, 11% je pod nekim stepenom ugroženosti ili zakonske zaštite. Metoda mikrocenoze se pokazala kao najadekvatniji metod za kvantitativna uzorkovanja prizemnih briofita (sa minimalnom adekvatnom veličinom kvadrata 0.5x0.5 m u šumskim odnosno 1x1 m na livadskim staništima). Za epifitske briofite, kao najadekvatnija se pokazale metoda postavljanja mikroplotova dimenzija 10x10 cm sa sve četiri strane stabla na međusobnoj udaljenosti od 20 cm. Struktura staništa ima značajno veći uticaj na diverzitet prizemnih briofita u šumskim staništima u odnosu na karakteristike zemljišta, dok je na livadskim<br />staništima zabeležen obrnut slučaj. Najveći uticaj na diverzitet epifitskih briofita ima visina na stablu kao i tip forofite. Na istraživanom području je detektovano devet zajednica u prizemnoj brioflori šumskih staništa; šest epifitskih zajednica; pet zajednica na livadskim staništima; četiri zajednice na trulim deblima i panjevima; 10 zajednica na stenama i kamenju; četiri zajednice u potocima. Dobijeni rezultati predstavljaju građu za dalja briološka istraživanja, kako floristička tako i ekološka, i dopunu flore Srbije.</p> / <p>In this research, the bryophyte flora of Fruška gora Mountain was analyzed. The aim of this research was to determine the diversity, distribution, microhabitat conditions and community structure of bryophytes on different types of habitats on Fruška Gora. Also, one of the goals was testing and optimization of the method for quantitative sampling of bryophytes on different types of habitats. Field research was carried out in the period 2013-2017. For the purposes of floristic research, field sampling was carried out using the transect method at 120 localities. Different variants of the "quadrat" method (method of nested quadrats for terrestrial bryophytes and the method of placing microplots at different distances for the epiphytic byphytes) were used for testing and optimization of methods for quantitative bryophyte sampling. Appropriate methods were selected on the basis species-area curve and similarity-area curve. Appropriate methods have been applied to further sampling in this study. On some localities (forest and meadow habitats) several environmental parameters (pH of soil and bark of wood, soil moisture, soil temperature, roof cover, coverage of herbaceous vascular plants, distance from the stream in forest habitats and distance of forest ecosystems in meadow habitats) were measured in order to determine their impact on the diversity and distribution of bryophytes. Bryophyte communities were identified on different substrates and habitat types using "label propagating community detection" analysis. The results of this study have shown that Fruška gora is an area characterized by a high diversity of bryophytes and a total number of 235 taxa were recorded (based on literature data and field research). 73 taxa were recorded for the first time on this area. Of the total number of taxa, 11% is threatened or under legislative protection. The microcenose method proved to be the most adequate for quantitative sampling of terrestrial bryophytes (with a minimum quadrat size of 0.5x0.5 m in forests and 1x1 m in meadow habitats). For the epiphytic bryophytes, the method of placing the microplots (10x10 cm) on all four sides of the tree at a distance of 20 cm is most suitable. The stand structure has a significantly greater influence on the diversity of terrestrial bryophytes in forest habitats compared to soil haracteristics, while in the meadow habitats there is a reverse case. The greatest influence on the diversity of epiphytic bryophytes has height on the tree as well as the type of phorphyte. In the investigated area, nine bryophyte communities were detected in ground bryopyhte flora of forest habitats; six epiphytic communities; five communities in meadow habitats; four communities on rotten trunks and horns; 10 communities on the rocks and stones; four communities in streams. The obtained results represent the base for further bryological research, both floristic and ecological, and the addition to the flora of Serbia.</p>
|
3 |
Benthic macroinvertebrate community structure responses to multiple stressors in mining-influenced streams of central Appalachia USADrover, 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.
|
Page generated in 0.1249 seconds