Ecological history affects zooplankton community responses to acidification

The effects of ecological history are frequently ignored in attempts to predict community responses to environmental change. In this study, we explored the possibility that ecological history can cause differences in community responses to perturbation using parallel acidification experiments in three sites with different pH histories in the Northern Highland Lake District of Wisconsin, USA. In Trout Lake, high acid neutralizing capacity had historically buffered changes in pH. In contrast, the two basins of Little Rock Lake (Little Rock-Reference and Little Rock-Treatment) had experienced seasonal fluctuations in pH. Furthermore, the two lake basins were separated with a curtain and Little Rock-Treatment was experimentally acidified in the late 1980s. In each site, we conducted mesocosm experiments to compare zooplankton community dynamics in control (ambient pH) and acidified (pH 4.7) treatments. Zooplankton community responses were strongest in Trout Lake and weakest in Little Rock-Treatment suggesting that ecological history affected responses to acidification. In part, variation in community sensitivity to acidification was driven by differences in species composition. However, the results of a reciprocal transplant experiment indicated that changes in the acid tolerance of populations during past acidification events may make zooplankton communities less sensitive to subsequent pH stress. Our study highlights the role that ecological history may play in community-level responses to environmental change

Occupational Therapy Practice Patterns In Two Rural States: Does The College Experience Influence Rural Employment Choice?

An online survey was conducted of 225 occupational therapy (OT) practitioners living in the rural states of North Dakota and Wyoming to explore practice patterns and the influence of the college experience on employment choice. Findings showed that rural practitioners had greater variability of hours spent working (5.5 more hours per week, p=.028), and one more work location on average (p=.006). Therapists in urban settings spent 15% more time in fieldwork education than their rural counterparts (p=.021). Rural practice choice was influenced by participation in Level I and Level II fieldwork (p=.002) but not by loan debt. Study implications for academic programs include focusing on multiple areas of practice in the curriculum design, and exposure of students to rural practitioners and rural practice examples/experiences. Recommendations were made for rural fieldwork educator training and employer support of rural fieldwork education. Further study of the experience of working within a rural practice context as a student and OT practitioner are recommended, including variables impacting rural practitioner work with fieldwork students, and student interest in rural fieldwork placement

Trajectories Of Zooplankton Recovery In The Little Rock Lake Whole‐Lake Acidification Experiment

Understanding the factors that affect biological recovery from environmental stressors such as acidification is an important challenge in ecology. Here we report on zooplankton community recovery following the experimental acidification of Little Rock Lake, Wisconsin, USA. One decade following cessation of acid additions to the northern basin of Little Rock Lake (LRL), recovery of the zooplankton community was complete. Approximately 40% of zooplankton species in the lake exhibited a recovery lag in which biological recovery to reference basin levels was delayed by 1–6 yr after pH recovered to the level at which the species originally responded. Delays in recovery such as those we observed in LRL may be attributable to “biological resistance” wherein establishment of viable populations of key acid-sensitive species following water quality improvements is prevented by other components of the community that thrived during acidification. Indeed, we observed that the recovery of species that thrived during acidification tended to precede recovery of species that declined during acidification. In addition, correspondence analysis indicated that the zooplankton community followed different pathways during acidification and recovery, suggesting that there is substantial hysteresis in zooplankton recovery from acidification. By providing an example of a relatively rapid recovery from short-term acidification, zooplankton community recovery from experimental acidification in LRL generally reinforces the positive outlook for recovery reported for other acidified lakes

Comparative cost of illness analysis and assessment of health care burden of Duchenne and Becker muscular dystrophies in Germany.

Our study aimed to determine the burden of illness in dystrophinopathy type Duchenne (DMD) and Becker (BMD), both leading to progressive disability, reduced working capacity and high health care utilization

Compensatory dynamics in planktonic community responses to pH perturbations

Compensatory population dynamics, in which species that decline in response to an environmental perturbation are replaced by similar species, may be crucial in maintaining processes performed by functional groups of species. Compensatory dynamics may be produced by negative interactions among species, such that the decrease in abundance of a species releases the suppression of another species and allows it to increase. We conducted a mesocosm experiment in Trout Lake, Wisconsin, USA, to test the hypothesis that compensatory shifts in species abundances play a role in overall planktonic community response to pH perturbation. In 2000-L mesocosms over a period of six weeks, we contrasted a control treatment with two acidified treatments (press, sustained pH = 4.7; and pulse, alternating pH = 4.7 and ambient pH). In the acidified treatments, we saw changes in abundance of the major zooplankton and phytoplankton species, but we observed few cases of compensatory dynamics. Nonetheless, when present, compensatory dynamics could be strong. Analyses using autoregressive models revealed negative interactions among species that could potentially lead to compensatory dynamics. However, this potential for compensatory dynamics was not realized in cases where all species were sensitive to the pH perturbations. Therefore, compensatory dynamics that buffer community responses to perturbations may be limited in communities in which many species are sensitive to the perturbation

Factors influencing the growth of Mougeotia in experimentally acidified mesocosms

Acidification causes profound changes in species composition in aquatic systems. We conducted mesocosm experiments in three northern Wisconsin lakes (Trout Lake, Little Rock - Reference, Little Rock - Treatment) to test how different phytoplankton communities respond to acidification. Major differences exist among these lakes in water chemistry and phytoplankton community composition. In each lake, three pH treatments (control, press (sustained pH 4.7), and pulse (alternating pH 4.7 and ambient pH)) were maintained for 6 weeks. We observed a striking increase in species in the genus Mougeotia in all systems. Mougeotia is a filamentous green alga often found in acidified lakes. The magnitude of the Mougeotia increase differed among lakes and treatments, and we used an autoregressive model to identify potential factors responsible for these differences. Our results suggest that biotic factors such as competition with other algae played a relatively minor role in regulating Mougeotia dynamics. Instead, pH and abiotic factors associated with changes in pH (e.g., dissolved inorganic carbon) were important predictors of Mougeotia dynamics

Disease burden of spinal muscular atrophy in Germany

Background: This study aimed at analyzing the economic burden and disease-specific health-related quality of life (HRQOL) of patients with spinal muscular atrophy (SMA) in Germany. SMA is a so far non-curable neuromuscular disease of the anterior nerve cells that causes high rates of morbidity and mortality. Methods: In a cross-sectional study we analyzed the cost of illness (COI) and factors that influence the direct, indirect and informal care costs of affected patients and their families by using standardized, self-developed questionnaires. We used the PedsQL (TM)(C) Measurement Model to analyze the disease-specific HRQOL of patients. Results: One hundred eighty nine patients with SMA types I to III aged <1 to 73 years were enrolled. The average annual COI was estimated at (sic)70,566 per patient in 2013. The highest cost resulted in SMA I with significant lower costs for the milder phenotypes. Inversely, the self-estimated HRQOL increased from SMA I to SMA III. Major cost drivers were informal care cost and indirect cost incurred by patients and their caregivers. Conclusions: Although SMA requires high standards of care, there has been a distinct lack of health services research on SMA. Accordingly, our results significantly contribute to a more comprehensive insight into the current burden of SMA and quality of life status as related to SMA health services in Germany. In the light of innovative therapeutic interventions, our results suggest a notable potential for a reduction in overall COI and improvement of HRQOL if the therapeutic intervention leads to a less severe course of the disease

Spatial pattern of localized disturbance along a southeastern salt marsh tidal creek

Geomorphology may be an important predictor of vegetation pattern in systems where suceptibility to disturbance is unevenly distributed across the landscape. Salt marsh communities exhibit spatial pattern in vegetation at a variety of spatial scales. In coastal Georgia, the low marsh is a virtual monoculture ofSpartina alterniflora interspersed with patches of species that are more typical of the high marsh. These localized disturbances are most likely created by wrack mats, mats of dead vegetation which can compact and smother underlying vegetation creating bare patches for colonization by high marsh species. We investigated the spatial pattern of disturbed patches along a 2 km section of Dean Creek, a tidal creek at the southwestern end of Sapelo Island, Georgia, U.S. We used a discriminant model to explore the relationship between tidal creek morphology (e.g., the presence of drainage channels and creek bends) and the spatial distribution of disturbed patches. The model predicted vegetation pattern along the creek with relatively high accuracy (\u3e70%). Areas where water movement is slowed or multidirectional (e.g., along creek bends and near drainage channels) were most susceptible to disturbance. Our findings suggest an important functional linkage between geomorphology and vegetation pattern in salt marsh communities

Trajectories of zooplankton recovery in the little rock lake whole-lake acidification experiment

Understanding the factors that affect biological recovery from environmental stressors such as acidification is an important challenge in ecology. Here we report on zooplankton community recovery following the experimental acidification of Little Rock Lake, Wisconsin, USA. One decade following cessation of acid additions to the northern basin of Little Rock Lake (LRL), recovery of the zooplankton community was complete. Approximately 40% of zooplankton species in the lake exhibited a recovery lag in which biological recovery to reference basin levels was delayed by 1-6 yr after pH recovered to the level at which the species originally responded. Delays in recovery such as those we observed in LRL may be attributable to biological resistance wherein establishment of viable populations of key acid-sensitive species following water quality improvements is prevented by other components of the community that thrived during acidification. Indeed, we observed that the recovery of species that thrived during acidification tended to precede recovery of species that declined during acidification. In addition, correspondence analysis indicated that the zooplankton community followed different pathways during acidification and recovery, suggesting that there is substantial hysteresis in zooplankton recovery from acidification. By providing an example of a relatively rapid recovery from short-term acidification, zooplankton community recovery from experimental acidification in LRL generally reinforces the positive outlook for recovery reported for other acidified lakes