Distribution, photobiology, salinity tolerance and population structure of Siderastrea radians and its symbionts in Florida Bay, Florida USA

The distribution of Siderastrea radians (Pallas) Blainville and photophysiology of its symbiont in Florida Bay were determined during annual macrophyte surveys in spring 2006 and 2007. Siderastrea radians was present in five of the eleven sampled basins in areas with little sediment and low abundance of the seagrass Thalassia testudinum. The five basins are located along a northeast-to-southwest transect that also represents a salinity gradient from inshore, predominantly estuarine conditions adjacent to the Everglades, to offshore near-marine salinities adjacent to the Gulf of Mexico. Colony abundance was highest in the two basins at the extremes of this physical range. Effective quantum yields, measured in situ by PAM fluorometry, were significantly correlated between S. radians and the dominant seagrass T. testudinum among all five basins where the two species co-occurred, albeit with a 40% reduction in mean yields of S. radians. These findings indicate S. radians may function as an alternative eco-indicator species for regions in which T. testudinum is absent and/or act as an indicator of stress for other benthic invertebrate taxa. The tolerance of S. radians to hyposalinity was examined in a mesocosm study using salinity treatment levels based on historical salinity records for the basins where this species occurs. Colonies of S. radians collected from the five basins in Florida Bay (i.e., along the northeast-to-southwest salinity gradient) were used to assess effects of hyposalinity on the photophysiology of the symbiont, as an indicator of holobiont stress. Colonies from each basin were assigned four salinity treatments (30, 20, 15, and 10) and salinities were reduced 2 d-1 from ambient (30) to simulate a natural salinity decrease. Maximum (Fv/Fm) and effective (?F/Fm') quantum yields were measured using PAM-fluorometry at dawn and noon, respectively. Because of high variability in ?F/Fm' in response to varying mid-day light conditions only Fv/Fm measurements were used to assess salinity treatment effects. There was generally no decrease in Fv/Fm for 20 and 15 treatment colonies versus controls (i.e. 30) up to five days post-target salinity. This indicates a greater ability to withstand reduced salinity for relatively extended periods of time in S. radians compared to other reef species. When salinity of 10 was reached, there was a significant reduction in Fv/Fm versus 20 and 30, indicating a critical threshold for hypo-saline tolerance. At salinity of 10, colony yields from the more salinity-variable northeast basins versus the most marine southwest Twin Key basin (TWN) were significantly different, suggesting populational acclimation or adaptation in salinity tolerance corresponding with historical basin salinity ranges. Genetic tools were used to determine whether differences among basin populations in photophysiological responses to hypo-saline stress were due to unique symbiont type among basin populations (i.e. adaptation) or to acclimation. Subcladal identification of Symbiodinium for each basin was completed using PCR-DGGE analysis of the ITS2 region of the rDNA. TWN colonies possessed an ITS2 variant distinct from all other basins, correlating with differences in photobiology measured during hyposalinity experiments. These findings suggest long-term differences among basin salinities lead to differential responses in the holobiont, which are related to a shift in symbiont photophysiology and symbiont adaptation. Despite low overall cover and frequency, S. radians in Florida Bay is a valuable marginal population for investigating tolerance to physical stressors across a natural physical gradient. Coral populations residing in marginal coastal habitats may provide insights as to how these communities will respond to higher environmental variability under predicted future climate patterns. The coral S. radians occurs along a physical-environmental gradient in Florida Bay that has been variably influenced by anthropogenic impacts to its watershed that have primarily affected salinity variability across the Bay. It is unclear what effects projected increased freshwater inflow under the Comprehensive Everglades Restoration Plan (CERP) will have on this community, but the results presented here indicate a greater tolerance to hyposaline conditions than generally reported for corals

Airport Traffic Conflict Detection and Resolution Algorithm Evaluation

Two conflict detection and resolution (CD&R) algorithms for the terminal maneuvering area (TMA) were evaluated in a fast-time batch simulation study at the National Aeronautics and Space Administration (NASA) Langley Research Center. One CD&R algorithm, developed at NASA, was designed to enhance surface situation awareness and provide cockpit alerts of potential conflicts during runway, taxi, and low altitude air-to-air operations. The second algorithm, Enhanced Traffic Situation Awareness on the Airport Surface with Indications and Alerts (SURF IA), was designed to increase flight crew awareness of the runway environment and facilitate an appropriate and timely response to potential conflict situations. The purpose of the study was to evaluate the performance of the aircraft-based CD&R algorithms during various runway, taxiway, and low altitude scenarios, multiple levels of CD&R system equipage, and various levels of horizontal position accuracy. Algorithm performance was assessed through various metrics including the collision rate, nuisance and missed alert rate, and alert toggling rate. The data suggests that, in general, alert toggling, nuisance and missed alerts, and unnecessary maneuvering occurred more frequently as the position accuracy was reduced. Collision avoidance was more effective when all of the aircraft were equipped with CD&R and maneuvered to avoid a collision after an alert was issued. In order to reduce the number of unwanted (nuisance) alerts when taxiing across a runway, a buffer is needed between the hold line and the alerting zone so alerts are not generated when an aircraft is behind the hold line. All of the results support RTCA horizontal position accuracy requirements for performing a CD&R function to reduce the likelihood and severity of runway incursions and collisions

Solar Radiation and Tidal Exposure as Environmental Drivers of Enhalus acoroides Dominated Seagrass Meadows

There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f.) Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010). Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs

Distribution and Photobiology of Siderastrea Radians and Thalassia Testudinum in Florida Bay, Florida, USA

The distribution of Siderastrea radians (Pallas) Blainville and photophysiology of its symbiont in Florida Bay, USA, were examined during annual macrophyte surveys in spring 2006 and 2007. Siderastrea radians was present in five of the 11 sampled basins in areas with little sediment and low abundance of the seagrass Thalassia testudinum Banks ex König. The five basins are located along a northeast-to-south-west transect that also represents a salinity gradient from inshore, predominantly estuarine conditions adjacent to the Everglades, to offshore near-marine salinities adjacent to the gulf of Mexico. Colony abundance was highest in the basins at the extremes of this physical range, presumably due to higher potential for larval recruitment from external reef source populations. Effective quantum yields, measured in situ by PAM fluorometry, were significantly correlated between S. radians and the dominant seagrass T. testudinum among all five basins where the two species co-occurred, albeit with a 40% reduction in mean yields of S. radians. These findings indicate S. radians may function as an alternative eco-indicator species for regions in Florida Bay where T. testudinum is absent

Population genetics of the blue shiner, Cyprinella caerulea

Cyprinella caerulea (Blue Shiner) is a federally threatened minnow endemic to the Mobile Basin that is currently restricted to four disjunct populations. We examined the Population structure in the Blue Shiner by sequencing the mitochondrial ND2 gene in 37 individuals. We recovered eleven haplotypes, with only one shared between populations, for an overall haplotype diversity of 0.768. Genetic differentiation between populations was significant, accounting for 26% of the variability found within the species. One individual morphologically identified as a Blue Shiner had a haplotype resolved with the sympatric Cyprinella trichroistia (Tricolor Shiner) in our phylogenetic analysis. Long-term management of the Blue Shiner should focus on restoring connectivity between Populations in order to restore natural patterns of gene flow

Lateral Growth from Existing Individuals

DBN CPT (visualised in supporting information S7

A gamification experience to improve engineering students' performance through motivation

The students' lack of motivation is a usual problem. The students value more the obtention of the degree than the developing of competences and skills. In order to fight this, we developed a gamification's experience based on merits and leaderboards. The merits are linked to the attainment of skills and competences that students usually do not appreciate. During the year 2016, we are carrying out a pilot involving 950 students at the Graduate of Engineering in Computer Science at the Autonomous University of Barcelona (UAB

Data from: Managing seagrass resilience under cumulative dredging affecting light: predicting risk using dynamic Bayesian networks

Coastal development is contributing to ongoing declines of ecosystems globally. Consequently, understanding the risks posed to these systems, and how they respond to successive disturbances, is paramount for their improved management. We study the cumulative impacts of maintenance dredging on seagrass ecosystems as a canonical example. Maintenance dredging causes disturbances lasting weeks to months, often repeated at yearly intervals. We present a risk-based modelling framework for time varying complex systems centred around a dynamic Bayesian network (DBN). Our approach estimates the impact of a hazard on a system's response in terms of resistance, recovery and persistence, commonly used to characterise the resilience of a system. We consider whole-of-system interactions including light reduction due to dredging (the hazard), the duration, frequency and start time of dredging, and ecosystem characteristics such as the life-history traits expressed by genera and local environmental conditions. The impact on resilience of dredging disturbances is evaluated using a validated seagrass ecosystem DBN for meadows of the genera Amphibolis (Jurien Bay, WA, Australia), Halophila (Hay Point, Qld, Australia) and Zostera (Gladstone, Qld, Australia). Although impacts varied by combinations of dredging parameters and the seagrass meadows being studied, in general, 3 months of duration or more, or repeat dredging every 3 or more years, were key thresholds beyond which resilience can be compromised. Additionally, managing light reduction to less than 50% can significantly decrease one or more of loss, recovery time and risk of local extinction, especially in the presence of cumulative stressors. Synthesis and applications. Our risk-based approach enables managers to develop thresholds by predicting the impact of different configurations of anthropogenic disturbances being managed. Many real-world maintenance dredging requirements fall within these parameters, and our results show that such dredging can be successfully managed to maintain healthy seagrass meadows in the absence of other disturbances. We evaluated opportunities for risk mitigation using time windows; periods during which the impact of dredging stress did not impair resilience

Data from: Managing seagrass resilience under cumulative dredging affecting light: predicting risk using dynamic Bayesian networks

Coastal development is contributing to ongoing declines of ecosystems globally. Consequently, understanding the risks posed to these systems, and how they respond to successive disturbances, is paramount for their improved management. We study the cumulative impacts of maintenance dredging on seagrass ecosystems as a canonical example. Maintenance dredging causes disturbances lasting weeks to months, often repeated at yearly intervals. We present a risk-based modelling framework for time varying complex systems centred around a dynamic Bayesian network (DBN). Our approach estimates the impact of a hazard on a system's response in terms of resistance, recovery and persistence, commonly used to characterise the resilience of a system. We consider whole-of-system interactions including light reduction due to dredging (the hazard), the duration, frequency and start time of dredging, and ecosystem characteristics such as the life-history traits expressed by genera and local environmental conditions. The impact on resilience of dredging disturbances is evaluated using a validated seagrass ecosystem DBN for meadows of the genera Amphibolis (Jurien Bay, WA, Australia), Halophila (Hay Point, Qld, Australia) and Zostera (Gladstone, Qld, Australia). Although impacts varied by combinations of dredging parameters and the seagrass meadows being studied, in general, 3 months of duration or more, or repeat dredging every 3 or more years, were key thresholds beyond which resilience can be compromised. Additionally, managing light reduction to less than 50% can significantly decrease one or more of loss, recovery time and risk of local extinction, especially in the presence of cumulative stressors. Synthesis and applications. Our risk-based approach enables managers to develop thresholds by predicting the impact of different configurations of anthropogenic disturbances being managed. Many real-world maintenance dredging requirements fall within these parameters, and our results show that such dredging can be successfully managed to maintain healthy seagrass meadows in the absence of other disturbances. We evaluated opportunities for risk mitigation using time windows; periods during which the impact of dredging stress did not impair resilience

Climate and environmental factors together with their averaging times used in Partial Least Squares (PLS) regression analysis of seagrass meadow changes at Weipa, North Queensland, Australia (2000 to 2010).

<p>Climate and environmental factors together with their averaging times used in Partial Least Squares (PLS) regression analysis of seagrass meadow changes at Weipa, North Queensland, Australia (2000 to 2010).</p