Spelling suggestions: "subject:"apopulation ecology."" "subject:"1population ecology.""
41 |
Variação geográfica no canto de anúncio de Dendropsophus Nanus (Anura, Hylidae) /Annibale, Fabiane Santana. January 2015 (has links)
Orientador: Fernando Rodrigues da Silva / Banca: Rogério Pereira Bastos / Banca: Fausto Nomura / Resumo: Anuros transmitem informações para coespecíficos principalmente através de sinais acústicos, cuja função principal é a reprodução. O sistema de comunicação pode apresentar variação geográfica devido à ação de diferentes forças evolutivas. O objetivo deste estudo foi testar as hipóteses de processos neutros, temperatura do ar e tamanho corpóreo para tentar entender quais variáveis influenciam o canto de anúncio de Dendropsophus nanus, uma espécie generalista com ampla distribuição na América do Sul. Foram amostradas nove populações em áreas de Cerrado no Brasil. O canto de anúncio da espécie é composto por dois tipos de notas: tipo A, relacionadas à competição entre machos e tipo B, que podem estar relacionadas à atração de fêmeas para reprodução assim, analisamos o efeito das variáveis sobre cada nota. Distância geográfica e temperatura do ar foram as principais variáveis que explicaram a variação em ambas as notas. Também observamos diferenças entre as populações de localidades leste e oeste. Como a temperatura está estruturada no espaço, a distância geográfica pode produzir diferença de temperatura ao longo de um gradiente longitudinal, refletindo a variação observada nos parâmetros entre populações. Tamanho corporal teve explicação apenas para as notas tipo B e também que indivíduos de populações que ocorrem em localidades mais quentes apresentaram menor tamanho corporal, assim como o oposto. Sugerimos que a variação nos parâmetros acústicos pode ser resultado indireto do efeito da temperatura sobre o tamanho do corpo. Finalmente, as populações de D. nanus amostradas neste estudo apresentam variação geográfica no canto de anúncio devido a processos neutros e ecológicos / Abstract: Anurans communicate information for conspecifics mainly through acoustic signals, whose principal function is reproduction. However, communication system may present geographic variation due to different evolutionary forces. In this study we aimed to test three non-exclusive hypotheses: random drift, environment temperature and body size hypothesis to understand which variables influenced variation in advertisement call of Dendropsophus nanus, a generalist species with large distribution in South America. We sampled nine populations in Cerrado domain in Brazil. The advertisement call of this species is composed by two types of notes: type A, related to male-male competition and type B that may attract females for reproduction so, we analyzed the effect of explanatory variables on each note. Geographical distance and temperature were the main variables explaining variation on both notes. Also we observed differences in the advertisement call among populations between western and eastern localities. As temperature is spatially structured, geographic distance may produce variation in temperature along the longitudinal gradient, reflecting the observed variation in bioacoustic parameters among populations. Body size had effect in variation of type B notes and also we observed that populations occurring in warmer localities presented smaller individuals such as the opposite. We suggest that variation in acoustic parameters may be an indirect result of temperature acting on body size. Therefore we found that the advertisement call of D. nanus present geographic variation due to neutral and ecological processes / Mestre
|
42 |
Ecologia populacional do bagre cego de Iporanga, Pimelodella kronei (Siluriformes: Heptateridae), do Vale do Alto Ribeira, Iporanga - SP: uma comparação com Trajano, 1987 / Population ecology of blind catfish from Iporanga, Pimelodella kronei (Siluriformes, Heptapteridae) in the Upper Ribeira Valley, Iporanga-SP: a comparison with Trajano, 1987Guil, Ana Luiza Feigol 20 September 2011 (has links)
O bagre cego de Iporanga, Pimelodella kronei, da região do Parque Estadual Turístico do Alto Ribeira-PETAR, SP, foi o primeiro peixe troglóbio descoberto e descrito no Brasil e um dos mais estudados até hoje. Populações de bagres cegos atribuídas a essa espécie foram encontradas, até o momento, em cavernas do Sistema das Areias (Areias de Cima - localidade-tipo e abrigando a maior população conhecida -, Areias de Baixo e Ressurgência das Areias da Água Quente, esta aparentemente com uma população periférica), na Caverna Córrego Seco, na Ressurgência de Bombas e em cavernas do Sistema Alambari (caverna Alambari de Cima - população aparentemente extinta -, e Abismo do Gurutuva). Os bagres cegos do Sistema Areias foram excessivamente coletados na década de 1970, o que teria provocado um declínio populacional acentuado, registrado por Trajano (1987) 10 anos mais tarde. O presente estudo aborda a ecologia de P. kronei, com ênfase na população das Areias, utilizando métodos comparáveis aos de Trajano (op. cit.), para fins de monitoramento. Os aspectos analisados nas Areias foram: tamanho da população, crescimento individual e deslocamentos no habitat, a partir de marcação e recaptura individual; estrutura da população em termos de distribuição das freqüências de tamanhos (comprimento-padrão), peso e fator de condição (isométrico e alométrico); troglomorfismos (graus de redução de olhos e de pigmentação melânica). Complementarmente, exemplares das Areias, Bombas, Córrego Seco e Gurutuva foram comparados quanto à morfometria. A população de P. kronei das Areias mostrou evidências de estabilidade através da recuperação da estrutura de peso e comprimento-padrão. Assim como observado para outras espécies de siluriformes troglóbios, o crescimento individual é altamente heterogêneo, com casos de crescimento negativo. Os parâmetros da equação de Von Bertallanfy revelaram valores superiores aos de Trajano (1987), resultando em uma longevidade média de 15-20 anos. Os bagres estudados na Areias de Cima mostraram tendência de deslocamentos rio acima, em direção ao ponto mais distal no Córrego Grande (mais próximo à entrada de alimento externo), provavelmente para alimentação e reprodução. É possível que existam diferenças entre a população de Bombas e as demais localidades, sendo necessária uma investigação mais aprofundada, com métodos mais discriminatórios. / The blind catfish from Iporanga, Pimelodella kronei, from Parque Estadual Turístico do Alto Ribeira- PETAR, SP, was the first troglobitic fish discovered and described in Brazil. It is also one of the most investigated species so far. Populations of blind catfish attributed to this species have been found in caves belonging to the Areias System (Areias de Cima - type-locality, sheltering the largest known population - , Areias de Baixo and Ressurgence of Areias of Águas Quente, which apparently shows a peripherical population), besides Córrego Seco Cave, Bombas Ressurgence and caves of the Alambari System (Alambari de Cima - an apparently extinct population - , and Gurutuva). The blind catfish of Areias system were over-collected during the 1970s, which may have led to an accentuated population decline, as recorded by Trajano (1987) ten years later. The present study focus on the ecology of P. kronei, with emphasis on the Areias population, by using methods comparable to those by Trajano (op. cit.) for monitoring purposes. The aspects studied in the Areias caves were: population size, individual growth and movements in the habitat, based on individual marking and recapture; population structure in terms of distribution of size (standard length), weight and condition factor (isometric and alometric) frequencies; troglomorphism (levels of eye reduction and melanic pigmentation). In addition, samples from Areias, Bombas, Córrego Seco and Gurutuva were morphometrically compared. The P. kronei population of Areias showed evidence of stability through the regain of the size and weight structure. Like the observed for other troglobitic siluriforms, the individual growth in P. kronei is highly heterogeneous, with frequent cases of negative growth. The parameters of the Von Bertallanfy equation calculated were higher than those by Trajano (1987), resulting in a higher expected longevity - 15 to 20 years. The blind catfish from Areias presented a tendency to move upstream, approaching the distal end of Córrego Grande (closer to the input of epigean nutrients), probably for feeding and reproduction. There may be some differences in the Bombas populations of other locations, to be investigated using more discriminatory methods.
|
43 |
Charter School Closures in Florida, 2006-2016: A Population Ecology PerspectiveUnknown Date (has links)
As part of the education reforms of the 1990s, charter schools were proposed as a
private alternative to public education, offering parents and their children greater choices.
Publicly financed but privately operated, charter schools have now grown in numbers and
influence. While there are many studies of student outcomes in charter schools
demonstrating mixed results, one negative outcome of charter schools has been less
examined. Since inception, 23% of charter schools nationally have closed and these
closures are disruptive to parents, children, and their school districts. This paper
addresses charter school closures from an organizational perspective. Applying theory
from population ecology and resource dependency theory, the population of nonprofit
charter schools is examined. What are the primary determinants of charter school success
and failure?
Florida, with the third highest number of charter schools nationally and, at the
same time, the highest number of charter school closures in the United States, is a paradox. This study identifies the significant variables that are related to school survival
and failure in the state of Florida over the years 2015-16 through 2015-16.
Variables tested in this study, using Survival Analysis (SA), include age,
management structure, size, school performance, grants, and density. All variables except
density at founding were significant in explaining the unique variance in survival rates
among charters. Charter schools sub-contracted by for-profit educational management
organizations (EMOs) were larger, achieved higher grades, secured more grants and
achieved higher survival rates than their counterpart nonprofit, independent, and charter
management organization (CMO) led schools. These results contribute to our
understanding of charter school survival and failure, thereby informing public policy
options to strengthen the charter school population and the nation’s public education
system overall. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
|
44 |
The sustainability of crayfish harvesting in Ranomafana National Park, MadagascarJones, Julia Patricia Gordon January 2004 (has links)
Madagascar's freshwater crayfish, belonging to the endemic genus Astacoides, are harvested throughout their range in the eastern highlands of the country. They provide an important source of protein and revenue to local communities but there is concern that the harvest may be unsustainable. In this thesis I assess the sustainability of crayfish harvesting in and around Ranomafana National Park, an area well known for its reliance on crayfish harvesting. Six taxa (belonging to four described species) are found in the Ranomafana area. Most families in villages with access to forest carry out some harvesting for subsistence use. Due to variation in local taboos (fady) and in access to forest, commercial crayfish harvesting is very important in only three of the 27 villages I visited. However, in these villages crayfish revenue is very important, particularly to poorer households. One species, Astacoides granulimanus, dominates the harvest: more than 95% of crayfish caught in the harvesting village of Vohiparara are of this species. I used a mark-and-recapture study involving more than 26,000 A. granulimanus across 79 sites under a range of harvesting intensities to estimate demographic parameters (growth, fecundity and survival) and investigate density-dependent control of growth and fecundity. No evidence for density-dependent control of growth was found, but the density of large crayfish negatively influenced the proportion of females of a given size which reproduced. I investigated the sustainability of the harvest of A. granulimanus using two approaches: I) comparing population structure and density under varying harvesting intensity and II) using population models to investigate the forest area necessary to provide the observed annual harvest from one harvesting village and comparing that with the area available. The conclusions are encouraging as they suggest that the A. granulimanus harvest in the Ranomafana area may be sustainable under current conditions. Preliminary work suggests habitat loss may be a more immediate threat, so scarce conservation resources should perhaps be concentrated on reducing habitat loss rather than enforcing a ban on harvesting.
|
45 |
Ecology of lawbreaking:effects of poaching on legally harvested wolf populations in human-dominated landscapesSuutarinen, J. (Johanna) 23 April 2019 (has links)
Abstract
Illegal killing of wolves (hereinafter ’wolf poaching’) in human-inhabited areas where wolves are also legally harvested is a special case of wildlife crime. This doctoral thesis examines wolf poaching in Finland and Sweden from the ecological perspective. In the first paper, we examined the causes of mortality among collared Finnish wolves and the role of estimated poaching rates on population changes. The second paper related the likelihood of being poached to covariates expressing different dimensions of the wolf conflict at two spatial scales (territory and country level) in Finland. Third paper turns the focus to Sweden, where we examined the disappearances of adult wolves in relation to population size, legal harvest and inbreeding. The first two studies were done in collaboration with the Natural Resources Institute Finland (Luke) and the third with the Scandinavian wolf research project SKANDULV. Poaching outnumbered other causes of death. Most poaching cases were unverified. Other causes of death were legal harvest, traffic and natural mortalities. Both populations had a relatively high number of wolves with unknown fates. Inbreeding was not related to the disappearances of adult wolves in Sweden. Remoteness to human inhabitation and the detectability of the wolves from the forest roads (road crossings by wolves) increased the likelihood of poaching in Finland. Adult wolves suffered high risk of poaching in both populations. Risk was highest in early spring in Finland. Larger population size increased and the number of legally harvested wolves decreased poaching in both countries. Poaching seemed to limit the study populations despite the management efforts that used legal hunting as a tool to increase tolerance towards wolves. / Tiivistelmä
Suden ja ihmisen rinnakkainelo johtaa konflikteihin, joiden lievittämiseksi susikantoja rajoitetaan usein luvallisella metsästyksellä. Suteen kohdistuu lisäksi laitonta tappamista eli salametsästystä. Tämä väitöstutkimus selvittää salametsästyksen ekologisia vaikutuksia Suomen ja Ruotsin susipopulaatioihin. Ensimmäisessä osatyössä selvitimme suomalaisten pantasusien kuolinsyitä, arvioimme salametsästyksen voimakkuutta ja sen vaikutuksia populaatiotasolla. Toisessa osatyössä tarkastelimme susikonfliktiin liittyvien ennustetekijöiden vaikutusta laittomasti tapetuksi tulemisen riskiin reviiritasolla ja koko Suomen mittakaavassa. Kaksi ensimmäistä osatyötä tehtiin Luonnonvarakeskuksen (Luke) suurpetotutkimuksessa. Kolmas osatyö tehtiin osana skandinaavista susitutkimushanketta (SKANDULV). Siinä selvitimme populaatiokoon, luvallisen pyynnin ja sukusiittoisuuden vaikutuksia aikuisten susien katoamiseen Ruotsissa. Salametsästys oli susien yleisin kuolinsyy, mutta suurin osa tapauksista jää toteen näyttämättä. Muita kuolinsyitä olivat luvallinen metsästys, liikenne ja luonnolliset kuolinsyyt. Aineistoissa oli runsaasti kohtaloltaan tuntemattomaksi jääneitä yksilöitä. Yksilöiden sukusiittoisuusaste ei ollut yhteydessä susien katoamisiin Ruotsissa. Syrjäinen sijainti ja susien havaittavuus metsätiestöltä lisäsivät laittoman tapon todennäköisyyttä Suomessa. Salametsästysriski oli korkein kevättalvella. Aikuisilla susilla oli huomattavan korkea riski tulla laittomasti tapetuksi. Tutkimuksen perusteella salametsästyksen määrää selittävät erityisesti susipopulaation kulloinenkin koko ja luvalliset pyyntimäärät. Suurempi susikanta lisäsi salametsästystä ja metsästyslupien määrä vähensi sen riskiä. Salametsästys vaikuttaa säädelleen susikantoja siitä huolimatta, että susikonfliktia on pyritty lieventämään luvallisella metsästyksellä.
|
46 |
Ecological responses to riverine floods and flow alterationMcMullen, Laura E. 11 July 2011 (has links)
Floods are major disturbance events for riverine ecosystems, directly and indirectly impacting organisms and their habitat. In this study I investigated the role of riverine floods and flow alteration in regulating aquatic macroinvertebrate population and community structure. I examined this problem using a variety of methods: a meta-analytic review of primary studies from the literature, a mathematical model synthesizing population and flood ecology, a multi-year experimental flood program in an arid-land river, and a field investigation of flood recovery behaviors in a charismatic larval odonate. I found that floods significantly reduced invertebrate abundance in the short term, but had varied effects across particular study sites, microhabitats, and taxonomic groups. I determined that both resistant and resilient capabilities are important to persistence of invertebrate populations after disturbance events, and that these traits may act in a binary fashion. Recovery over time of invertebrate populations may be partially due to "hidden resistance" of spatially displaced individuals in side-channels, benthic substrate, and vegetation or wood. Some invertebrates adapted to flood-prone rivers may possess behavioral adaptations for returning to the main-channel of the river after flood events. This dissertation contributes to riverine disturbance ecology and provides information useful to prediction and management of ecosystem flows in rivers. / Graduation date: 2012
|
47 |
The Effects of Recreational Trail Design and Management Decisions on Northern Leopard Frog (Rana pipiens) Populations in an Urban ParkMcAllister, Catherine January 2006 (has links)
In addition to their original purpose as recreational areas, urban parks provide important habitats for species living in urban settings. Reconciling recreational and environmental goals is problematic, especially for park planners. RIM Park, in Waterloo, Ontario, is an example of this attempted reconciliation, where planners and managers attempted to conserve herpetofauna in a provincially significant wetland. However, this area includes a paved nature trail used by hikers, in-line skaters and cyclists and is adjacent to a golf course (which lies within the boundaries of the park). Herpetofauna breeding ponds were constructed and a series of culverts and clearspans included in order to provide reptiles and amphibians with safe passage under the trails. My objective was to determine whether these measures have been effective, whether the park sustains a viable population of Northern Leopard Frogs, and what factors influence frog populations in the park. Two spring field seasons involving mark and recapture techniques were attempted to estimate population sizes of Northern Leopard Frogs at RIM Park, as well as control sites. In both seasons, a control site was a cedar swamp 14 km to the west of the park within an Environmentally Sensitive Policy Area in Waterloo city limits affected by housing development and shared trails. Also within Waterloo city limits, a storm water management pond 8 km to the west was added in field season two. In 2005 (field season 1), because there was a serious drought almost no Northern Leopard Frogs were captured at the two sites examined ? RIM Park and the cedar swamp. In 2006, the more "normal" weather conditions revealed that RIM Park had significantly fewer Northern Leopard Frogs than either of the control sites. Given the lack of data in year 1, I compared the 2006 results to seven years of monitoring reports on RIM Park from consultants. The 2006 data were consistent with previous reports of small Northern Leopard Frog populations at RIM Park. Mark and recapture sessions revealed relatively low numbers, with a catch average of 4. 33 (SD = 1. 15). Calculations revealed an estimated population of 23 (SE = 13. 42). The highest number of observed Northern Leopard Frogs ever recorded at the same location in consulting reports is 5. It is likely that the ponds at RIM Park do not support breeding in Northern Leopard Frogs as the only adults caught were late in the season, during the last week of May, and adults likely were transients from the nearby wetlands and uplands. It is possible, given the historical monitoring data, that the Northern Leopard Frogs were long absent from RIM Park because of intensive farming activities that had replaced the wetlands, and that construction of the golf course and trails further precluded colonization. The lack of adult frogs in the breeding ponds and the lack of dead or injured frogs on the trails or golf course support the hypothesis that the trails are not presently causing frog mortality. It is possible that the frogs are avoiding recolonizing the trail and golf course area. It is also likely that the breeding ponds need to be deepened and only then will it be apparent whether the frogs will colonize the ponds, lay eggs, and use the clearspans and culverts. Recommendations include a shift in priorities to put the emphasis on restoration, a discussion of restoration options (including a possible restoration plan), possible improvements in amphibian monitoring techniques (such as reducing the reliance on audio methods), and general suggestions for urban park planning and management.
|
48 |
The Effects of Recreational Trail Design and Management Decisions on Northern Leopard Frog (Rana pipiens) Populations in an Urban ParkMcAllister, Catherine January 2006 (has links)
In addition to their original purpose as recreational areas, urban parks provide important habitats for species living in urban settings. Reconciling recreational and environmental goals is problematic, especially for park planners. RIM Park, in Waterloo, Ontario, is an example of this attempted reconciliation, where planners and managers attempted to conserve herpetofauna in a provincially significant wetland. However, this area includes a paved nature trail used by hikers, in-line skaters and cyclists and is adjacent to a golf course (which lies within the boundaries of the park). Herpetofauna breeding ponds were constructed and a series of culverts and clearspans included in order to provide reptiles and amphibians with safe passage under the trails. My objective was to determine whether these measures have been effective, whether the park sustains a viable population of Northern Leopard Frogs, and what factors influence frog populations in the park. Two spring field seasons involving mark and recapture techniques were attempted to estimate population sizes of Northern Leopard Frogs at RIM Park, as well as control sites. In both seasons, a control site was a cedar swamp 14 km to the west of the park within an Environmentally Sensitive Policy Area in Waterloo city limits affected by housing development and shared trails. Also within Waterloo city limits, a storm water management pond 8 km to the west was added in field season two. In 2005 (field season 1), because there was a serious drought almost no Northern Leopard Frogs were captured at the two sites examined ? RIM Park and the cedar swamp. In 2006, the more "normal" weather conditions revealed that RIM Park had significantly fewer Northern Leopard Frogs than either of the control sites. Given the lack of data in year 1, I compared the 2006 results to seven years of monitoring reports on RIM Park from consultants. The 2006 data were consistent with previous reports of small Northern Leopard Frog populations at RIM Park. Mark and recapture sessions revealed relatively low numbers, with a catch average of 4. 33 (SD = 1. 15). Calculations revealed an estimated population of 23 (SE = 13. 42). The highest number of observed Northern Leopard Frogs ever recorded at the same location in consulting reports is 5. It is likely that the ponds at RIM Park do not support breeding in Northern Leopard Frogs as the only adults caught were late in the season, during the last week of May, and adults likely were transients from the nearby wetlands and uplands. It is possible, given the historical monitoring data, that the Northern Leopard Frogs were long absent from RIM Park because of intensive farming activities that had replaced the wetlands, and that construction of the golf course and trails further precluded colonization. The lack of adult frogs in the breeding ponds and the lack of dead or injured frogs on the trails or golf course support the hypothesis that the trails are not presently causing frog mortality. It is possible that the frogs are avoiding recolonizing the trail and golf course area. It is also likely that the breeding ponds need to be deepened and only then will it be apparent whether the frogs will colonize the ponds, lay eggs, and use the clearspans and culverts. Recommendations include a shift in priorities to put the emphasis on restoration, a discussion of restoration options (including a possible restoration plan), possible improvements in amphibian monitoring techniques (such as reducing the reliance on audio methods), and general suggestions for urban park planning and management.
|
49 |
Environmental Impacts on the Population Dynamics of a Tropical Seabird in the Context of Climate Change: Improving Inference through Hierarchical ModelingColchero, Fernando 25 April 2008 (has links)
<p>Under the increasing threat of climate change, it is imperative to understand the impact that environmental phenomena have on the demography and behavior of natural populations. In the last few decades an ever increasing body of research has documented dramatic changes in mortality rates and breeding phenology for a large number of species. A number of these have been attributed to the current trends in climate change, which have been particularly conspicuous in bird populations. However, datasets associated to these natural populations as well as to the environmental variables that affect their biology tend to be partial and incomplete. Thus, ecological research faces the urgent need to tackle these questions while at the same time develop inferential models that can handle the complex structure of these datasets and their associated uncertainty. Therefore, my dissertation research has focused on two main objectives: 1) to understand the relationship that demographic rates and breeding phenology of a colony of seabirds has with the environment in the context of climate change; and 2) to use and develop models that can encompass the complex structure of these natural systems, while also extending the process not only to inference but to building predictions. I divided this work in three research projects; for the first one I developed a hierarchical Bayesian model for age-specific survival for long lived species with capture-recapture data that allows the use of incomplete data (i.e. left-truncated and right-censored), and builds predictions of years of birth and death for all individuals while also drawing inference on the survivorship function. I compared this method to more traditional ones and address their limitations and advantages. My second research chapter makes use of this method to determine the age-specific survivorship of the Dry Tortugas sooty tern population, and explores the effect of changes in sea surface temperature on their cohort mortality rates. Finally, my third research chapter addresses the dramatic shift in breeding season experienced by the Dry Tortugas sooty tern colony, the most unprecedented shift reported for any bird species. I explore the role of climatic and weather variables as triggering mechanisms.</p> / Dissertation
|
50 |
Historical and Current Population Patterns of the Staghorn Coral (_Acropora cervicornis_) in Dry Tortugas National ParkLizza, Kaitlyn 01 January 2015 (has links)
Acropora cervicornis was once one of the dominant reef building corals of the Caribbean, Florida Keys, and Dry Tortugas (DRTO), but since the 1970’s populations have been decimated throughout their geographic range. Recently, a repopulation was documented through detailed benthic surveys conducted by the U.S. Geological Survey at three locations (Pulaski Shoal, East Key, and Loggerhead Key) within DRTO. Benthic surveys using the U.S Geological Survey’s Along-Track Reef Imaging System (ATRIS) revealed hundreds of previously undocumented colonies.
These discoveries have provided a unique data-set, allowing a comparison between the historical (1883, 1976) and contemporary distributions (2009, 2011) of A. cervicornis. Kernel density estimates were used to analyze shifts in high density areas and non-parametric multivariate analysis of variance tests were used to analyze differences between years in location and extent of the distribution. The results from the KDEs indicated high density areas have shifted among year’s at all three study areas. The comparison of the location and extent of the historical and modern A. cervicornis distributions revealed similarities and differences among years that varied among the study areas. This information is important to the management of this species because it provides vital information on the extent and location of the current distribution relative to historical levels. This study also provides documentation of the population dynamics and ecosystem changes over large time scales within the DRTO region.
The above mentioned dataset was also used in a second study to quantify 1) variations in density among factors such as location (study area), suitable habitat type, and water depth, 2) overall spatial population patterns, and 3) spatial patterns in A. cervicornis density. Results indicated population structure was significantly clustered (P = 0.001) at Pulaski Shoal and Loggerhead Key with areas containing hotspots or significantly higher density (P < 0.05). Although significant hotspots existed, density did not significantly differ among suitable habitat types. Compared to all other factors, water depth had the largest effect on the variation in mean density of A. cervicornis. These findings are vital to understanding the recovery of this species in terms of current habitat and depth associations.
|
Page generated in 0.0843 seconds