Resource Partitioning Among Three Mesoconsumers at a Marsh Mangrove Ecotone: a Response to a Seasonal Resource Pulse Subsidy

Pulse subsidies account for a substantial proportion of resource availability in many systems, having persistent and cascading effects on consumer population dynamics, and the routing of energy within and across ecosystem boundaries. Although the importance of resource pulses is well-established, consumer responses and the extent of resource partitioning is not well understood. I identified a pulse of marsh cyprinodontoid, invertebrate, and sunfish prey, entering an estuary, which was met by an influx of both marsh and estuarine predators. In response to the pulse, consumers showed marked diet segregation. Bass consumed significantly more cyprinodontoids, bowfin consumed significantly more invertebrates, and snook almost exclusively targeted sunfishes. The diversity of the resource pulse subsidizes multiple consumers, routing pulsed production through various trophic pathways and across ecosystem boundaries. Preserving complex trophic linkages like those of the Everglades ecotone may be important to maintaining ecosystem function and the provisioning of services, such as recreational fisheries

Investigating Sub-tropical Community Resistance and Resilience to Climate Disturbance

Changes in global climate will likely increase climate variability. In turn, changes in climate variability have begun to alter the frequency, intensity, and timing of climate disturbances. Continued changes in the climate disturbance regime experienced by natural systems will undoubtedly affect ecological processes at every hierarchical scale. Thus, in order to predict the dynamics of ecological systems in the future, we must develop a more mechanistic understanding of how and in what ways climate disturbance affects natural systems. In South Florida, two climate disturbances recently affected the region, a severe cold spell in 2010, and a drought in 2011. Importantly, these disturbances affected an ecosystem of long-term, comprehensive, and persistent ecological study in the Shark River estuary in the Everglades National Park. The aims of my dissertation were to (1) assess the relative severity of these two climate disturbances, (2) identify effects of these disturbances on community structuring, (3) compare community change from the 2010 cold spell with community change from another extreme cold spell that affected sub-tropical China in 2008, (4) assess the effects of the drought on predator prey interactions in the Shark River and (5) apply a spatial approach to predicting population resistance to these events. My results show that the 2010 cold spell was the most severe cold event to affect the Shark River in the last 80 years, while the drought was the worst drought to occur in the last 10 years. The cold spell drove community change that was predictable based on the traits of component species, whereas community change was less predictable using trait-based approaches. When comparing community change from the extreme 2010 event in Florida with the event in China, I identified three consistencies related to community change from extreme cold events that occurred across both events that will help build generalized understanding of community resistance to increasingly extreme climate events in the future. From the trophic study, I found that the drought reduced prey for estuarine piscivores. Not only was prey biomass reduced, the drought drove a compositional shift in prey communities from fish to invertebrates, which are lower in calories. Last, I found that animal movement may create temporally dynamic resistance scenarios that should be accounted for when developing predictive models

Shift in recreational fishing catches as a function of an extreme cold event

There is an increasing recognition that the influence of extreme climate events (ECE) can be more significant in structuring ecosystem dynamics than the gradual effects of climate change. Still, our understanding of the effects of climate extremes on ecosystem services such as marine fisheries lags behind those of effects of gradual change. The significance of ECEs depends on the severity of the disturbance event and the resilience of a fish community. South Florida experienced an extreme cold spell in 2010 that provided the opportunity to study recreational fisheries resilience to ECEs. Our main goal was to examine how recreational fishing catch structures responded to the cold spell, and illustrate any spatial-specific recovery trajectory dynamics after extreme ecological responses. To address this, we implemented multivariate and nonlinear statistics on fishing guide reports for 20 recreational species. A significant shift in the catch structure occurred after the event, suggesting a high sensitivity of fish populations and fisheries in the region to ECEs. All fishing regions considered were affected, but the trajectory of the response and recovery varied across study areas. While some fish species experienced an expected decline (due to mortality), other species manifested an increase in catch. Of the main seven species considered in nonlinear models, three experienced a decline (bonefish, snook, goliath grouper), two experienced an increase (red drum, gray snapper), and the two had various weak trends (tarpon, spotted seatrout). Three years after the event, the catch structure has not returned to the original state, indicating a possible state shift, whose stability needs to be determined in future tracking of affected populations. Future work should also address the extent to which harvest may interfere with resilience to ECEs. Our work highlights the need to account for rare environmental forcing induced by ECEs to ensure the ecological and economical sustainability of key services such as recreational fisheries

Resilience of a tropical sport fish population to a severe cold event varies across five estuaries in southern Florida

For species that are closely managed, understanding population resilience to environmental and anthropogenic disturbances (i.e., recovery trajectories across broad spatial areas) can guide which suite of management actions are available to mitigate any impacts. During January 2010, an extreme cold event in south Florida caused widespread mortality of common snook, Centropomus undecimalis, a popular sport fish. Interpretation of trends using fishery-independent monitoring data in five south Florida estuaries showed that changes in catch rates of adult snook (\u3e500 mm standard length) varied between no effects postevent to large effects and 4-yr recoveries. The reasons for the variation across estuaries are unknown, but are likely related to differences in estuary geomorphology and habitat availability (e.g., extent of deep rivers and canals) and differences in the proportions of behavior contingents (i.e., segments of the population that use divergent movement tactics) that place snook in different areas of the estuary during winter. Emerging awareness of the presence of behavior contingents, identification of overwintering sites, and improvements of abundance indices in remote nursery habitats should provide a better understanding of population resilience to disturbance events for snook. Given that changes in the frequency of short-lived, severe cold events are currently unknown, the findings and management actions described here for a tropical species living at the edge of its distribution should be useful to scientists forecasting the effects of climate change

Episodic disturbances drive nutrient dynamics along freshwater‐to‐estuary gradients in a subtropical wetland

Wetlands are biogeochemically active ecosystems where primary production and respiration interact with physico‐chemical conditions to influence nutrient availability across spatio‐temporal scales. The effect of episodic disturbances on water quality dynamics within wetlands is relatively unknown, especially in large oligotrophic wetlands such as the Everglades. We describe a range of episodic disturbance events and their impacts on the spatio‐temporal dynamics of surface water total N (TN) and total P (TP) concentrations in the Everglades as a means to understand their effect and legacies. Water quality monitoring along the two principal drainages—Taylor Slough (TS) and Shark River Slough (SRS)—has been ongoing since 2000, spanning myriad disturbances ranging from high‐energy storms such as Hurricane Wilma in 2005 to a record cold event in 2010 and large fires. Local events include pulsed rainfall, low marsh stage, and stage recession and recovery (i.e., droughts and subsequent dry‐to‐wet transitions). The deposition of marine‐derived sediment from Hurricane Wilma corresponded with a doubling of TP in SRS mangrove sites (from 0.39 to 0.84 μmol/L) before recovering to pre‐disturbance mean after 5–6 yr. A brief increase in TP within one week of the 2010 cold event was followed by delayed spikes in TN (\u3e1000 μmol/L) and TN:TP exceeding 5000 after one month. In 2008, a large fire in upper SRS prior to the wet season caused a lagged TP pulse at downstream locations SRS2, SRS3, and possibly SRS4. TP also varied negatively with depth/stage in marsh sites and positively with salinity in estuarine sites, reflecting physical concentration or dilution effects. In upper TS, TP varied according to extremes such as high rainfall and low stage relative to normal conditions. Although excess P in the Everglades is generally derived from anthropogenic upland or natural marine sources, episodic disturbance mobilizes internal sources of nutrients along an Everglades freshwater‐to‐estuary continuum, affecting water quality from days to years depending on disturbance type and intensity. The capacity for resilience is high in coastal wetland ecosystems that are exposed to high‐energy tropical storms and other episodic events, even in the highly managed Florida Everglades

Ecological-economic assessment of the effects of freshwater flow in the Florida Everglades on recreational fisheries

This research develops an integrated methodology to determine the economic value to anglers of recreational fishery ecosystem services in Everglades National Park that could result from different water management scenarios. The study first used bio-hydrological models to link managed freshwater inflows to indicators of fishery productivity and ecosystem health, then link those models to anglers\u27 willingness-to-pay for various attributes of the recreational fishing experience and monthly fishing effort. This approach allowed us to estimate the foregone economic benefits of failing to meet monthly freshwater delivery targets. The study found that the managed freshwater delivery to the Park had declined substantially over the years and had fallen short of management targets. This shortage in the flow resulted in the decline of biological productivity of recreational fisheries in downstream coastal areas. This decline had in turn contributed to reductions in the overall economic value of recreational ecosystem services enjoyed by anglers. The study estimated the annual value of lost recreational services at $68.81million. The losses were greater in the months of dry season when the water shortage was higher and the number of anglers fishing also was higher than the levels in wet season. The study also developed conservative estimates of implicit price of water for recreation, which ranged from$11.88 per AF in November to $112.11 per AF in April. The annual average price was$41.54 per AF. Linking anglers\u27 recreational preference directly to a decision variable such as water delivery is a powerful and effective way to make management decision

Chronic kidney disease after liver, cardiac, lung, heart–lung, and hematopoietic stem cell transplant

Patient survival after cardiac, liver, and hematopoietic stem cell transplant (HSCT) is improving; however, this survival is limited by substantial pretransplant and treatment-related toxicities. A major cause of morbidity and mortality after transplant is chronic kidney disease (CKD). Although the majority of CKD after transplant is attributed to the use of calcineurin inhibitors, various other conditions such as thrombotic microangiopathy, nephrotic syndrome, and focal segmental glomerulosclerosis have been described. Though the immunosuppression used for each of the transplant types, cardiac, liver and HSCT is similar, the risk factors for developing CKD and the CKD severity described in patients after transplant vary. As the indications for transplant and the long-term survival improves for these children, so will the burden of CKD. Nephrologists should be involved early in the pretransplant workup of these patients. Transplant physicians and nephrologists will need to work together to identify those patients at risk of developing CKD early to prevent its development and progression to end-stage renal disease

A prospective phase II trial exploring the association between tumor microenvironment biomarkers and clinical activity of ipilimumab in advanced melanoma

<p>Abstract</p> <p>Background</p> <p>Ipilimumab, a fully human monoclonal antibody that blocks cytotoxic T-lymphocyte antigen-4, has demonstrated an improvement in overall survival in two phase III trials of patients with advanced melanoma. The primary objective of the current trial was to prospectively explore candidate biomarkers from the tumor microenvironment for associations with clinical response to ipilimumab.</p> <p>Methods</p> <p>In this randomized, double-blind, phase II biomarker study (ClinicalTrials.gov NCT00261365), 82 pretreated or treatment-naïve patients with unresectable stage III/IV melanoma were induced with 3 or 10 mg/kg ipilimumab every 3 weeks for 4 doses; at Week 24, patients could receive maintenance doses every 12 weeks. Efficacy was evaluated per modified World Health Organization response criteria and safety was assessed continuously. Candidate biomarkers were evaluated in tumor biopsies collected pretreatment and 24 to 72 hours after the second ipilimumab dose. Polymorphisms in immune-related genes were also evaluated.</p> <p>Results</p> <p>Objective response rate, response patterns, and safety were consistent with previous trials of ipilimumab in melanoma. No associations between genetic polymorphisms and clinical activity were observed. Immunohistochemistry and histology on tumor biopsies revealed significant associations between clinical activity and high baseline expression of FoxP3 (p = 0.014) and indoleamine 2,3-dioxygenase (p = 0.012), and between clinical activity and increase in tumor-infiltrating lymphocytes (TILs) between baseline and 3 weeks after start of treatment (p = 0.005). Microarray analysis of mRNA from tumor samples taken pretreatment and post-treatment demonstrated significant increases in expression of several immune-related genes, and decreases in expression of genes implicated in cancer and melanoma.</p> <p>Conclusions</p> <p>Baseline expression of immune-related tumor biomarkers and a post-treatment increase in TILs may be positively associated with ipilimumab clinical activity. The observed pharmacodynamic changes in gene expression warrant further analysis to determine whether treatment-emergent changes in gene expression may be associated with clinical efficacy. Further studies are required to determine the predictive value of these and other potential biomarkers associated with clinical response to ipilimumab.</p

Analysis of arterial intimal hyperplasia: review and hypothesis

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Despite a prodigious investment of funds, we cannot treat or prevent arteriosclerosis and restenosis, particularly its major pathology, arterial intimal hyperplasia. A cornerstone question lies behind all approaches to the disease: what causes the pathology? Hypothesis: I argue that the question itself is misplaced because it implies that intimal hyperplasia is a novel pathological phenomenon caused by new mechanisms. A simple inquiry into arterial morphology shows the opposite is true. The normal multi-layer cellular organization of the tunica intima is identical to that of diseased hyperplasia; it is the standard arterial system design in all placentals at least as large as rabbits, including humans. Formed initially as one-layer endothelium lining, this phenotype can either be maintained or differentiate into a normal multi-layer cellular lining, so striking in its resemblance to diseased hyperplasia that we have to name it &quot;benign intimal hyperplasia&quot;. However, normal or &quot;benign &quot; intimal hyperplasia, although microscopically identical to pathology, is a controllable phenotype that rarely compromises blood supply. It is remarkable that each human heart has coronary arteries in which a single-layer endothelium differentiates earl