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Spatial and temporal winter territory use and behavioral responses of whooping cranes to human activitiesLaFever, Kristin E. 02 June 2009 (has links)
I investigated spatial and temporal winter behavior and behavioral responses of 5
territorial whooping crane families to human activities at Aransas National Wildlife
Refuge during winters 2003-2004 and 2004-2005. Adult and juvenile cranes spent the
majority of the day foraging (63% and 66%, respectively). Alert behavior comprised
15% of the cranes' time-activity budgets; preening or resting, and movement each
constituted approximately 7% of the time-activity budget. Adults were more alert than
juveniles in Jan-Feb. The proportion of time spent in other behaviors did not differ by
age.
Over-winter use of territories varied spatially and temporally. Flight occurrence
was highest in Nov-Dec, coinciding with establishment of territorial boundaries upon
arrival at the wintering grounds. Movement velocity (meters traveled/min) also tended
to be highest in Nov-Dec, which may be due to territorial defense and foraging activities.
Use of land, open water, and edge habitats (land and water interface) within territories
appeared to fluctuate with primary food item availability. Disproportionate use of land
habitat by several crane families coincided with peak production of wolfberry (Lycium
carolinianum) fruit, which occurs in Nov-Dec. Edge habitat was used disproportionately to its availability throughout the winter, most likely because this habitat type provided
refuge for blue crabs (Callinectes sapidus), an important food item for whooping cranes.
Several families also used open water disproportionately to its availability.
Behavioral responses of whooping cranes to human activities were limited.
Responses to varying frequency and intensity of human stimuli were evaluated. Most
stimuli did not elicit a response. Two crane families decreased the proportion of time
spent foraging during periods of high-intensity stimuli; one family increased movement
during such times. Foraging behavior of one family was significantly higher when
stimuli frequency was high; alert behavior significantly declined as stimuli frequency
increased. The mixed responses of territorial families to varying levels of human stimuli
paired with the overall high level of reproductive success of the entire population led to
my conclusion that current levels of human activities are not having a detrimental impact
on the Aransas-Wood Buffalo whooping crane population.
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Ecosystem oxygen metabolism in an impacted temperate river network: Application of the δ18O-DO approachChen, Gao January 2013 (has links)
Ecosystem metabolism is an important indicator of aquatic ecosystem function. This thesis concerns ecosystem metabolism as recorded by daily variation in dissolved oxygen (DO) and δ18O-DO in an impacted temperate river network, the Grand River, Ontario, Canada, and specifically addresses the effects of stream size and human disturbance including agriculture, deforestation, and wastewater treatment plants (WWTPs). A suite of 14 sites in the Grand River network was selected with stream sizes varying from 2nd to 7th order.
A transient model of river ecosystem oxygen metabolism, ROM-TM, was developed in order to calculate river ecosystem metabolic rates and reaeration rates from field observation of changes in DO and δ18O-DO. ROM-TM is an inverse modeling approach programmed using MATLAB. Key parameters describing the main metabolic processes, gas exchange, and isotopic fractionation, such as maximum photosynthetic rate (Pm), photosynthetic efficiency (a), respiration rate at 20℃ (R20), gas exchange coefficient (k), respiration isotopic fractionation factor (aR), and photorespiration coefficient (βR), can be obtained by matching of model predictions with field data. Besides being capable of teasing apart metabolic processes and gas exchange to provide daily average estimates of metabolic parameters at the ecosystem level, ROM-TM can be used to address issues related to light including light saturation phenomena at the ecosystem level, the effect of cloud cover on metabolic balance and photorespiration.
Primary production responses to light along a longitudinal gradient in the Grand River network were described by means of P-I curves. Both light-limited and light-saturated conditions were observed. Production parameters Pm and Ik in the Grand River network exhibited an increase with stream order, while a was independent of stream size. However, a did vary among and within sites.
Higher light availability in small and middle-sized streams without riparian trees was associated with high Pm, Ik and Ec, but low a. Ecosystem-level Pm in both small periphyton-dominated streams and large macrophyte-dominated rivers in the Grand River basin were generally less than community-level Pm values from the literature. However, two Grand River sites had comparable Pm to literature-derived Pm due to the prolific growth of macrophytes supported by high nutrient effluents from upstream WWTPs. Ecosystem-level a in my study streams were also less than those at the community level, indicating there was a declining trend of this parameter with scale, from individual, community to ecosystem. Derived parameters (e.g., Ik, Ec, and saturation point) increased from the individual level to the community level, and then to the ecosystem level.
From May to early October, metabolic rates in the Grand River network (gross primary production, GPP = 0.4 to 20 and ecosystem respiration, ER = 2 to 33 g O2 m-2 day-1) were within the broad range of metabolic rates occurring in the temperate region, regardless of stream size. The Grand River network is a net heterotrophic system. The total GPP and ER for whole basin was 3.3e+08 and 4.2e+08 g O2 day-1, respectively.
Reach geomorphology controls the spatial patterns of stream metabolism in the Grand River network, although the spatial patterns may be modified by effects of human disturbance on riparian vegetation, nutrients and other factors. Stream order and channel width, as measures of stream size, are good predictors of metabolic rates and ratios of GPP: ER from small streams to the central Grand River. Ecosystem metabolic rates and ratios generally increase with stream size, but with site-specific variation.
The Grand River network is experiencing effects of human disturbance, mostly downstream of the urban areas and least in small streams with remaining riparian forest. The small and middle-sized streams (2nd to 4th order) without riparian trees in agriculture regions in the Grand River basin did not exhibit significantly different GPP and ER than their counterparts with riparian trees. The stimulative effect of increased light availability due to open canopy on GPP in non-shaded streams may be offset by shading from stream banks and riparian grasses, and unstable sediments resulting from agricultural activities. Large river sites impacted by WWTPs had significantly increased metabolic rates, both GPP and ER, compared to two upstream sites impacted by agriculture only. This result suggests that urban areas cause impacts on the Grand River that are superimposed on the impacts of agriculture.
Three aspects of metabolism of the Grand River differ from the general pattern for the temperate regions: (1) a increase trend of GPP: ER ratios with stream size from 2nd to 7th order; (2) overall, human activities in the Grand River watershed have stronger positive effects on the GPP than on the ER; (3) the middle-sized to large river sites (5th-7th order) had greater influence than small to middle-sized streams (2nd-5th order) in the Grand River on overall GPP and ER.
The general trend of GPP: ER ratio in tropical, subtropical, temperate, and global data approximately conforms to the predictions of the River Continuum Concept (RCC). However, the maximum ratio of GPP: ER in mid-reaches of river networks is not usually >1 as proposed in the RCC. There is a latitude and stream size shift phenomenon regarding where the peak ratio of GPP: ER occurs in each climate zone. The maximum GPP: ER ratio is higher at higher latitudes and occurs at higher order streams.
The study of stream ecosystem metabolism can benefit from the addition of the second oxygen budget, δ18O-DO, in four ways: (1) it is better to use both DO and δ18O-DO budgets, rather than DO only, in sampling protocols with low temporal frequency but high spatial frequency; (2) the δ18O-DO time series data can provide relatively independent constraints on parameter estimation; (3) the addition of δ18O-DO in using two oxygen budgets to quantify metabolic rates provides a way, the cross-plot of δ18O-DO against fraction of DO saturation, to indicate trophic status of an aquatic ecosystem; and (4) the addition of δ18O-DO can provide an estimate of aR at the ecosystem level that can be used to understand factors affecting respiration.
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The effects of human disturbance on birds in Bastrop State ParkMarcum, Heidi Ann 30 October 2006 (has links)
With rapidly disappearing natural areas due to development and fragmentation,
public lands provide important habitat for birds. However, the increasing use of public
lands for recreation may decrease the value of these areas for bird use. Human
disturbance can damage birds in many ways, including disrupting foraging or social
behavior, increasing nest predation, interfering with parent-offspring and pair bonds,
increasing nesting failures, and reducing the viability of fledglings. Additionally, birds
may perceive humans as predators and leave an area, and the resulting decline in species
abundance resembles the effects of habitat loss. Increased human outdoor activity has
created the need for information regarding the effects of human disturbance on birds. I
investigated the effects of human disturbance on birds in Bastrop State Park (BSP) in
central Texas in 1998 and 1999. A wide variety of people use much of BSP, and many
areas within the park experience significant amounts of disturbance from people and
vehicles, particularly in campgrounds. I evaluated the effects of various types of human
disturbance on the presence of 20 avian species, including seven neotropical migratory
species. Brown-headed Cowbird (Molothrus ater), Mourning Dove (Zenaida macroura), Carolina Wren (Thryothorus ludovicianus), and Summer Tanager (Piranga
rubra), were sensitive to human presence, and Blue Jays (Cyanocitta cristata), and
Downy Woodpeckers (Picoides pubescens) occurred in lower abundances in sites with
higher numbers of vehicles. However, other species (e.g., American Crow [Corvus
brachyrhynchos], Black-and-white Warbler [Mniotilta varia], Pileated Woodpecker
[Dryocopus pileatus], Red-eyed Vireo [Vireo olivaceus], Ruby-throated Hummingbird
[Archilochus colubris], White-eyed Vireo [Vireo griseus], and Yellow-billed Cuckoo
[Coccyzus americanus]) tolerated humans, vehicles, or both. Neotropical migratory
species did not show higher sensitivity to disturbance when compared to resident
species, and forest interior species were not more sensitive than edge species. My
results indicate that some species, including migrants, can become habituated to human
presence in protected areas with low harassment and low-intensity, predictable
disturbances. Management recommendations for BSP include protecting habitat,
minimizing human disturbance in some areas, providing buffer zones between humandominated
zones and sites containing vulnerable species, and softening edges in
campgrounds.
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Effects and consequences of agriculture, tourism and hunting on the birdlife at Gialova lagoon : An area of international importance for migratory birdsSöderblom-Tay, David January 2014 (has links)
Many populations of migrating waterbirds in Africa and Western Eurasia are in a long-term decline, largely because of the loss of wetlands along their migration routes. Between 1950 and 1985, 63 % of the wetlands in Greece were lost due to human activities. However, humans are also a source of more direct disturbance to birds that may have a negative influence on their fitness. The purpose of this study has been to assess how human disturbance in the form of agriculture, tourism and hunting might affect the birdlife in a coastal lagoon in southwestern Greece, and, if needed, propose measures on how to improve the status of the birdlife. To evaluate this, interviews and studies of monitoring reports and literature have been conducted. The studied area, Gialova lagoon, is the southernmost wetland in the Balkan Peninsula, which makes it especially important for migratory birds. The study shows that the major threats to the lagoon have already been dealt with. However, there are still improvements that can be made. Currently, agriculture seems to have the most negative effect on the concerned area, but since there appears to be an ambition to increase tourism in the area this may change in the future. Disturbance from hunting only plays a minor role in the area around the lagoon. The establishment of an official management body as well as an official management plan would probably be an effective way to continue the conservation work and reduce the disturbance of human activities in Gialova lagoon.
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Ecosystem oxygen metabolism in an impacted temperate river network: Application of the δ18O-DO approachChen, Gao January 2013 (has links)
Ecosystem metabolism is an important indicator of aquatic ecosystem function. This thesis concerns ecosystem metabolism as recorded by daily variation in dissolved oxygen (DO) and δ18O-DO in an impacted temperate river network, the Grand River, Ontario, Canada, and specifically addresses the effects of stream size and human disturbance including agriculture, deforestation, and wastewater treatment plants (WWTPs). A suite of 14 sites in the Grand River network was selected with stream sizes varying from 2nd to 7th order.
A transient model of river ecosystem oxygen metabolism, ROM-TM, was developed in order to calculate river ecosystem metabolic rates and reaeration rates from field observation of changes in DO and δ18O-DO. ROM-TM is an inverse modeling approach programmed using MATLAB. Key parameters describing the main metabolic processes, gas exchange, and isotopic fractionation, such as maximum photosynthetic rate (Pm), photosynthetic efficiency (a), respiration rate at 20℃ (R20), gas exchange coefficient (k), respiration isotopic fractionation factor (aR), and photorespiration coefficient (βR), can be obtained by matching of model predictions with field data. Besides being capable of teasing apart metabolic processes and gas exchange to provide daily average estimates of metabolic parameters at the ecosystem level, ROM-TM can be used to address issues related to light including light saturation phenomena at the ecosystem level, the effect of cloud cover on metabolic balance and photorespiration.
Primary production responses to light along a longitudinal gradient in the Grand River network were described by means of P-I curves. Both light-limited and light-saturated conditions were observed. Production parameters Pm and Ik in the Grand River network exhibited an increase with stream order, while a was independent of stream size. However, a did vary among and within sites.
Higher light availability in small and middle-sized streams without riparian trees was associated with high Pm, Ik and Ec, but low a. Ecosystem-level Pm in both small periphyton-dominated streams and large macrophyte-dominated rivers in the Grand River basin were generally less than community-level Pm values from the literature. However, two Grand River sites had comparable Pm to literature-derived Pm due to the prolific growth of macrophytes supported by high nutrient effluents from upstream WWTPs. Ecosystem-level a in my study streams were also less than those at the community level, indicating there was a declining trend of this parameter with scale, from individual, community to ecosystem. Derived parameters (e.g., Ik, Ec, and saturation point) increased from the individual level to the community level, and then to the ecosystem level.
From May to early October, metabolic rates in the Grand River network (gross primary production, GPP = 0.4 to 20 and ecosystem respiration, ER = 2 to 33 g O2 m-2 day-1) were within the broad range of metabolic rates occurring in the temperate region, regardless of stream size. The Grand River network is a net heterotrophic system. The total GPP and ER for whole basin was 3.3e+08 and 4.2e+08 g O2 day-1, respectively.
Reach geomorphology controls the spatial patterns of stream metabolism in the Grand River network, although the spatial patterns may be modified by effects of human disturbance on riparian vegetation, nutrients and other factors. Stream order and channel width, as measures of stream size, are good predictors of metabolic rates and ratios of GPP: ER from small streams to the central Grand River. Ecosystem metabolic rates and ratios generally increase with stream size, but with site-specific variation.
The Grand River network is experiencing effects of human disturbance, mostly downstream of the urban areas and least in small streams with remaining riparian forest. The small and middle-sized streams (2nd to 4th order) without riparian trees in agriculture regions in the Grand River basin did not exhibit significantly different GPP and ER than their counterparts with riparian trees. The stimulative effect of increased light availability due to open canopy on GPP in non-shaded streams may be offset by shading from stream banks and riparian grasses, and unstable sediments resulting from agricultural activities. Large river sites impacted by WWTPs had significantly increased metabolic rates, both GPP and ER, compared to two upstream sites impacted by agriculture only. This result suggests that urban areas cause impacts on the Grand River that are superimposed on the impacts of agriculture.
Three aspects of metabolism of the Grand River differ from the general pattern for the temperate regions: (1) a increase trend of GPP: ER ratios with stream size from 2nd to 7th order; (2) overall, human activities in the Grand River watershed have stronger positive effects on the GPP than on the ER; (3) the middle-sized to large river sites (5th-7th order) had greater influence than small to middle-sized streams (2nd-5th order) in the Grand River on overall GPP and ER.
The general trend of GPP: ER ratio in tropical, subtropical, temperate, and global data approximately conforms to the predictions of the River Continuum Concept (RCC). However, the maximum ratio of GPP: ER in mid-reaches of river networks is not usually >1 as proposed in the RCC. There is a latitude and stream size shift phenomenon regarding where the peak ratio of GPP: ER occurs in each climate zone. The maximum GPP: ER ratio is higher at higher latitudes and occurs at higher order streams.
The study of stream ecosystem metabolism can benefit from the addition of the second oxygen budget, δ18O-DO, in four ways: (1) it is better to use both DO and δ18O-DO budgets, rather than DO only, in sampling protocols with low temporal frequency but high spatial frequency; (2) the δ18O-DO time series data can provide relatively independent constraints on parameter estimation; (3) the addition of δ18O-DO in using two oxygen budgets to quantify metabolic rates provides a way, the cross-plot of δ18O-DO against fraction of DO saturation, to indicate trophic status of an aquatic ecosystem; and (4) the addition of δ18O-DO can provide an estimate of aR at the ecosystem level that can be used to understand factors affecting respiration.
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Evaluating the impacts of human-mediated disturbances on species’ behaviour and interactionsFrey, Sandra 27 August 2018 (has links)
Developing effective conservation strategies requires an empirical understanding
of species' responses to human-mediated disturbances. Observable responses are typically limited to dramatic changes such as wildlife population declines or range shifts.
However, preceding these obvious responses, more subtle responses may signal larger-scale future change, including changes in species' behaviours and interspecific interactions.
Disturbance-induced shifts to species' diel activity patterns may disrupt mechanisms of niche partitioning along the 24-hour time axis, altering community structure via altered competitive interactions. I investigate the main questions and methods of analysis applicable to camera-trap data for furthering our understanding of temporal dynamics in animal communities. I apply these methods to evaluate the impacts of human-mediated disturbance on species' activity patterns and temporal niche partitioning in two separate studies, focusing on responses in the mammalian carnivore community. In the Canadian Rocky Mountain carnivore guild, species alter diel activities in relation to anthropogenic landscape development, although these shifts may be manifesting through indirect biotic effects instead of direct responses to human disturbance. Mesocarnivore species on a mixed-use landscape featuring anthropogenic land-use and introduced free-ranging dogs (Canis familiaris) shift activities in relation to spatiotemporal dog activity. Native carnivores partition diel activities differently on open landscapes of enhanced predation risk but abundant prey resources. Detecting shifts in species' temporal behaviours and competitive interactions may enable identification of potential precursors of population declines and shifting community assemblages, providing us with opportunities to pre-emptively manage against such biodiversity losses on human-modified landscapes. / Graduate
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The unseen world of coral reefs: impact of local and global stressors on coral microbiome community structureMcDevitt-Irwin, Jamie 04 May 2017 (has links)
Diverse and abundant coral associated microbial communities may play a key role in coral resistance to and recovery from unwavering stressors currently threatening coral reefs worldwide. The composition and structure of the coral microbiome is integral to
coral health as microbes can play beneficial (e.g. nutritional or protective) or negative
(e.g. pathogenic or opportunistic) roles in the coral. To review the impacts of stressors on the coral microbiome, I compiled data from 39 studies, each tracking microbial community shifts in corals experiencing stress from climate change, pollution or overfishing. Stress was associated with shifts in coral microbial communities. I found that regardless of stressor, microbial alpha diversity increased under stress, with Vibrionales,
Flavobacteriales and Rhodobacterales commonly found on stressed corals, and Oceanospirillales not as abundant on stressed corals. In addition, I used 16S rRNA sequencing to evaluate how local and global stressors affect the community structure of the coral microbiome for the two coral species, Porites lobata and Montipora foliosa. I
monitored tagged coral colonies at two human disturbance levels (i.e. high and low),
before and during a thermal bleaching hotspot at Kiritimati, Kiribati. Human disturbance,
a bleaching hotspot, and coral species were all important drivers of coral microbiome
community structure. My results suggest that human disturbance increases microbial
alpha and beta diversity, although results vary between coral species, with P. lobata
having more of a difference between disturbance levels. Similarly, bleaching increased
beta diversity at low disturbance sites. Both human disturbance and thermal stress
appeared to homogenize coral microbiomes between species and thermal stress appeared
to homogenize communities between disturbance levels. Thus, both human disturbance
and bleaching appear to stress the coral and destabilize its microbiome. However, intense
thermal stress (i.e. 12.86 DHWs) appears to have a greater influence than human
disturbance, probably due to corals responding to stressful conditions in a similar manner.
In conclusion, my results highlight the impact of local and global stressors on coral
microbiome community structure. / Graduate / 2018-04-26 / 0359
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An Analysis of Human Disturbance to Rocky Intertidal Communities of San Luis Obispo CountyWaltz, Grant Tyler 01 December 2012 (has links)
ABSTRACT
An Analysis Of Human Disturbance To Rocky Intertidal Communities Of San Luis Obispo County
Grant Tyler Waltz
The number of coastal areas open to public access in California and San Luis Obispo County is increasing due to the acquisition by California State Parks of land previously owned by private entities. For example, California State Parks acquired property from the Hearst Corporation in 2005, which included 18 miles of coastline. California State Parks is responsible for providing public access in these newly acquired areas and also for maintaining the health of the natural systems found on these properties. Part of the California State Parks’ strategic vision maintains that they seek to consider the impacts of every decision they make on the next seven generations of Californians. To balance the competing demand of providing access with long-term sustainability, State Parks managers require sound scientific data to evaluate the impacts of human access to the ecosystems they manage.
One ecosystem susceptible to human access in these new State Park areas and in other areas throughout the state is the rocky intertidal (e.g. Beauchamp and Gowing 1982, Ghazanshahi et al. 1983, Hockey and Bosman 1986, Povey and Keough 1991, Addessi 1994, Fletcher and Frid 1996, Brown and Taylor 1999, Murray et al. 1999, Van De Werfhorst and Pearse 2007). This thesis represents a collaborative effort between State Parks Managers scientists at California Polytechnic State University San Luis Obispo, and scientists at Tenera Environmental Inc. to provide sound scientific data on the impacts of visitors to rocky intertidal biological communities in San Luis Obispo County. A three-pronged approach was used to assess the effect of visitors to rocky intertidal communities: 1) an observational study to quantify visitor densities in publicly accessible rocky intertidal communities, 2) an experimental manipulation of visitor density to rocky intertidal communities based on the visitor densities observed in part 1 and used to identify organisms susceptible to foot traffic (access-indicator taxa), and 3) an observational study of publicly accessible rocky intertidal sites exposed to levels of foot traffic shown to cause declines in access-indicator taxa from part 2. I was involved with all three portions of the study and my thesis is focused on presenting and discussing parts 1 and 3 in detail.
Visitor counts and the observational access-indicator taxa study (parts 1 and 3) were conducted in Montaña de Oro State Park (MDO) in San Luis Obispo County from 2007-2009. There was abundant accessible rocky intertidal coastline in the park. Three popular rocky intertidal sites were chosen within the park to conduct visitor counts. Visitors were quantified from fixed locations on the bluff above each of the three observation sites on sixteen occasions during the course of three years. These counts were used to estimate the annual number of visitors to each site. The area of each intertidal observation site was also calculated and with the annual number of visitors, was used to calculate the annual density of visitors to the rocky intertidal at each site. This represents a novel approach to quantifying visitor numbers to rocky intertidal communities. Additionally, I examined whether there was a relationship between the number of cars entering the park and the density of rocky intertidal visitors or between the number of cars parked at each site and the density of rocky intertidal visitors.
The annual density of visitors at one of the observation sites in MDO, Hazard Reef, was shown to be approximately equal to the moderate treatment level from the experimental study (part 2). This moderate level of visitor density was shown to significantly reduce the abundance of five rocky intertidal taxa: rockweed (Silvetia compressa, Hesperophycus californicus, and Fucus gardneri), Endocladia muricata, Mastocarpus papillatus, limpets, and chitons. To assess whether long-term exposure to foot traffic could impact the abundance of access-indicator taxa in MDO, the abundance of these taxa was sampled at Hazard Reef and compared to the abundance of the same taxa at two adjacent sites with much lower annual densities of visitors. A stratified random sampling design was used to assess the abundance of the five access-indicator taxa found in the mid-intertidal zone at these three sites in the spring of 2009.
My work demonstrated that visitor densities and patterns of use were variable among the three accessed intertidal sites in MDO. Annual visitor numbers to the rocky intertidal for the three observation sites within MDO were between 3,000-5,000 people. There was no relationship between the number of cars entering the park and the annual density of visitors to the rocky intertidal. The number of parked cars was significantly related to visitor density at one study site suggesting that under specific circumstances, controlling parking lot size may be a viable approach to managing impacts to intertidal areas. Significant differences in limpet density (60 per m2) were detected in a moderately accessed intertidal site relative to adjacent and less visited sites. The abundance of combined algae and limpets were lower at the moderate use site when the lower use sites were compared together against it. Patterns of rocky intertidal habitat use and the estimated annual visitor density suggest that some areas in San Luis Obispo County may be exposed to damaging levels of visitors. The current study identified that the abundance of one out of five experimentally identified access-indicator taxa (Rockweed, Mastocarpus papillatus, Endocladia muricata, Limpets, and Chitons) had been significantly reduced at a popular rocky intertidal site, relative to adjacent and less visited sites.
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Stress in the Red-cockaded Woodpecker: Hormonal Mechanisms of Reproductive Suppression in Helper Males and Impacts of Military Training ActivitiesMalueg, Amanda Leah 16 October 2007 (has links)
The measurement of stress hormone levels in wild free-living animals is becoming an increasingly effective method for examining proximate mechanisms of animal behavior and the physiological impacts of human activities on wildlife. In these studies I measured plasma levels of the stress hormone corticosterone in the endangered red-cockaded woodpecker (Picoides borealis) to determine their role in the reproductive behavior of individuals in this species, and whether they are affected by human disturbance. In chapter one, I provide an introduction to the vertebrate stress response and I describe the natural history of the red-cockaded woodpecker. In chapter two, I compare corticosterone and reproductive hormone levels between breeding males and helper males to examine hormonal mechanisms of reproductive suppression in helper males. No hormonal differences existed between breeding and helper males. However, baseline corticosterone levels were lower in all males living in groups with two or more helper males, suggesting that male helpers reduce the workload of all other group members. In chapter three, I compare corticosterone levels between birds living in clusters subject to two different training restriction regimes on a military installation. Males living in clusters without training restrictions had lower baseline corticosterone than those living in clusters with training restrictions, suggesting that males habituate to chronic disturbance by downregulating baseline corticosterone levels. / Master of Science
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THE ROLE OF SOCIALITY AND DISTURBANCE IN SHAPING ELK (CERVUS CANADENSIS) POPULATION STRUCTURESlabach, Brittany L. 01 January 2018 (has links)
Investigating how and why individuals interact is an important component to understanding species ecology. The type and patterning of relationships (social structure) provides pertinent insight into how ecological factors such as spatial heterogeneity of resources and predation influence associations between individuals. Many taxa exhibit temporally fluid association patterns, where individuals associate with a variety of others at different rates. Ungulate species exhibit prime examples of highly fluid grouping patterns and individuals form both temporary and long-term associations. The effects of human disturbance on ungulate behavior are well documented and these changes are further exacerbated during the hunting season. Species such as elk (Cervus canadensis) are highly managed having subsistence, recreational, and economic value. The demographic effects of selective take or harvest regimes on population dynamics are known, but how human disturbance, including hunting, influences ungulate social structure on a fine-scale has not been explored. I aimed to investigate the relationship between human disturbance and social structure in a population of elk residing in southeastern, Kentucky, USA. I choose to focus on female elk given the importance of adult female survival to population dynamics and previous knowledge of some social affinity between females. I begin by discussing factors that influence ungulate sociality, how human disturbance can influence sociality and how a better understanding of association patterns could aid in management decisions. I then present two distinct yet vital studies to understanding this relationship: (1) investigation of survival of elk in Kentucky and (2) investigation of association patterns in a human dominated landscape. Hunter harvest is the primary cause of elk mortality in both eastern and western populations in North America and 85.2% of all elk mortalities in Kentucky were hunter harvest related. Older (> 5) males and younger (< 2) females had significantly higher hazards of dying relative to other age classes. Moreover, the establishment of a limited entry hunting area to prevent local overharvest of males had no effect on male survival, but instead may have resulted in local overharvest of females at one site residing on publicly accessible land. Female elk exhibit both weak and strong association patterns. I found that relatedness was significantly greater within sites, similar to patterns found in other cervid species. Association patterns within sites were not explained by age class; and relatedness was only positively correlated at one site. The sites investigated differed in the type and frequency of human disturbance, specifically hunting, suggesting that the disparity in association patterns were driven by these differences. I conclude with two smaller studies, suggesting an indirect consequence of coal surface mining disturbance on ungulate foraging behavior and the potential for interstate transfer of ecto-parasites during reintroduction efforts. This research reinforces previous findings and further refines our understanding of ungulate social structure. Consideration of temporal variation in association patterns of ungulates and other species is important to quantify the effect of disturbance on population and social processes, but also to increase our understanding of dynamic structures. Quantifying the resiliency of structure to disturbance is a priority to further our understanding of the ecology and conservation of these species.
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