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"Red tide" is the popular name for a harmful algal bloom that occurs frequently in Florida waters and has significant impacts on the environment, the economy, and human and animal health. This paper addresses the limited understanding of public attitudes surrounding red tide and the potential for message framing to increase support for mitigation action. A sample of Florida residents (n = 498) was randomly shown a digital article framed around different red tide impacts (economic loss, human health risks, ecosystem damage, or harm to charismatic species) or a control article not framed around a specific red tide impact. Participants were then queried about their emotional responses, support for red tide mitigation policies, and intentions to change their behavior to mitigate impacts. Participants reported higher levels of negative emotions after viewing the harm to charismatic megafauna framing, indicating that messaging may play a significant role in eliciting environmental emotions. Message frames did not significantly impact other policy attitudes. Results demonstrate barriers to shifting support for mitigation where public support for action is already high. [ABSTRACT FROM AUTHOR]

An assessment framework for Tampa Bay Water's Hydrobiological Monitoring Program (HBMP) has been established based on the relationship between freshwater flow and primary environmental indicators monitored under the HBMP. The underlying paradigm is based on the understanding that reduced flows can result in water quality conditions adverse to biological populations if these conditions exceed a specific magnitude and/or are beyond a certain duration. HBMP water quality parameters identified as primary indicators include salinity (due to osmotic pressure controlling distribution of fish, benthos, and vegetation among other ecological effects), dissolved oxygen (due to the aerobic stress to fish and benthos that can occur due to depressed dissolved oxygen concentrations), and chlorophyll-a (due to excessive phytoplankton blooms that may increase biological oxygen demand and can result in depressed dissolved oxygen concentrations). These primary indicators were identified because they specifically relate to linkages in the HBMP conceptual model as well as State of Florida water quality standards and a great deal of effort has been allocated to understanding these relationships. To this end, special studies have been implemented to further scientific information related to the effects of flows and withdrawals on the magnitude, duration, and distribution of phytoplankton as one aspect of the larger HBMP assessment framework. In this paper, we provide a summary of recent special studies completed in the lower Alafia River, focused on in situ fluorometer chlorophyll-a measurement, interpretation, and predictive capability. We share lessons learned and our steps for moving forward in efforts to relate flow (and withdrawal-related effects) on phytoplankton in the lower Alafia River. [ABSTRACT FROM AUTHOR]

Lake Okeechobee is Florida's largest lake, the largest lake in the Southeast United States, and the second largest lake contained entirely within the United States. The history of this inland sea is marked both by natural processes, and more recently human development and intervention. Adventurers can explore this behemoth of a waterway via the Lake Okeechobee Scenic Trail that enriches it, a part of the Florida National Scenic Trail. This paper synthesizes major natural and human-induced perturbations that shaped the lake and ultimately the trail that encircles it to create a narrative of Florida's great lake. The story of Lake Okeechobee is a story of battles, first between the land and sea, then between the lake itself and humankind. For the past few centuries Lake Okeechobee's natural perturbations in water flow and flooding resisted the control of man, until recently when man triumphed, managing to control the flow of water in and out of the lake. Unfortunately, with this new found control a new bioecological threat in the form of harmful algal blooms has emerged, which again threatens the health and livelihood of South Floridians. Currently there are new efforts that seek to restore Lake Okeechobee towards a more natural state in an effort to thwart the blooms. [ABSTRACT FROM AUTHOR]

We present AquaNutriOpt, a user-friendly Python package designed to tackle a complex combinatorial optimization problem aimed at optimizing nutrient management for the control of harmful algal blooms. This optimization process involves the identification of optimal Best Management Practices (BMPs) and Treatment Technologies (TTs). AquaNutriOpt is constructed based on a novel integer programming model, which we present in this paper. The package can accommodate various user inputs, automatically transforming them into an optimization model, and then solving it using a free solver. To demonstrate AquaNutriOpt's efficacy, we conduct a series of experiments on two watersheds around Lake Okeechobee in Florida, USA. These experiments illustrate that the optimal BMPs/TTs obtained by AquaNutriOpt can significantly reduce Phosphorus loads into the lake across various budget scenarios. We validate the results by running simulations with the process-based Watershed Assessment Model (WAM), confirming that the estimated percentage reductions closely align with the reports from WAM. • We study controlling harmful algal blooms (HABs) through nutrient optimization. • We develop a novel mathematical optimization model for nutrient optimization. • We develop a software package in Python based on the proposed model. • We show the efficacy of the package in a case study in Lake Okeechobee in Florida. [ABSTRACT FROM AUTHOR]

Water pollution threatens public health, especially in Florida, where excess nutrients cause reoccurring algal blooms. The law itself has become the problem. Florida serves as a case study in micro-deregulation because its system of environmental regulation has been incrementally dismantled through a combination of legally mandated "drops." Some deregulation occurred openly through exemptions, presumptions, preemptions, and deadline-driven procrastination. Other efforts are less transparent. Exercises of agency discretion, often based on vague standards, may be known to the government but hidden from public view. Furthermore, justice is willfully blind because the judiciary refuses to listen to citizen advocates, invoking doctrines of judicial restraint, standing, and fee-shifting to undermine access to courts in environmental affairs. Finally, some of the deregulatory efforts will never be truly understood due to the unknown impacts of appropriations and other structural deregulatory efforts. But as water quality continues to decline, Florida's citizens endure the consequences of deregulation, one drop at a time. [ABSTRACT FROM AUTHOR]

Introduction: Successful management and mitigation of harmful algal blooms (HABs) requires an in-depth understanding of the physiology and nutrient utilization of the organisms responsible. We explored the preference of various nitrogen (N) and phosphorus (P) substrates by two novel groups of HAB-forming phytoplankton originating from the Indian River Lagoon (IRL), Florida: 1) a consortium of picocyanobacteria (Crocosphaera sp. and 'Synechococcus' sp.) and 2) ananochlorophyte (Picochlorum sp.). Methods: Short-term kinetic uptake experiments tested algal use and affinity for inorganic and organic N substrates (ammonium (NH4 +), nitrate (NO3 -), urea, and an amino acid (AA) mixture) through 15N and 13C isotope tracing into biomass. Results: Picocyanobacteria exhibited Michaelis-Menten type uptake for the AA mixture only, while nanochlorophytes reached saturation for NH4 +, the AA mixture, and urea at or below 25 µM-N. Both picocyanobacteria and nanochlorophyte cultures had highest affinity (Vmax/Ks) for NH4 + followed by the AA mixture and urea. Neither culture showed significant uptake of isotopically-labeled nitrate. Disappearance of glucose-6-phosphate (G6P) added to culture medium suggesting use of organic P by both cultures was confirmed by detection of alkaline phosphatase activity and the tracing of 13CG6P into biomass. Discussion: Together, our results suggest that these HAB-forming phytoplankton groups are able to use a variety of N and P sources including organic forms, and prefer reduced forms of N. These traits are likely favorable under conditions found in the IRL during periods of significant competition for low concentrations of inorganic nutrients. Bloom-forming phytoplankton are therefore able to subsist on organic or recycled forms of N and P that typically dominate the IRL nutrient pools. [ABSTRACT FROM AUTHOR]

Despite years of efforts to improve water quality, harmful algal blooms remain a chronic phenomenon, with devastating environmental, economic, and social impacts in many regions worldwide. In this study, we assessed the complexity of nutrient pollution attributed to harmful algal blooms in South Florida (USA) by analyzing 20 years of flow and nutrient data within two headwater basins in the Lake Okeechobee (LO) watershed. The study used an established advanced regression method, the Weighted Regression on Time, Discharge, and Season (WRTDS) method, as an analysis framework to examine the impact of nutrient management practices on water quality trends. The WRTDS method produced total phosphorus (TP) and total nitrogen (TN) concentration and flux trends, which were then compared with existing and historic nutrient management records within the basin. Results from this study highlight divergences in progress to improve water quality. Nutrient management practices only had a weak impact on TP and TN flux trends in one of the two basins, where TP flux decreased 2% per year, and TN flux decreased 0.1% per year. TP and TN flux increased in the second basin. Variances of improvement between the two basins are likely attributable to differences in contemporary point source loading and legacy nutrient pools from non-point source inputs 20 years or more before the analysis period. The long-lasting impacts of legacy nutrients also emphasize a need for investments in technologies and practices that can withdraw nutrients from enriched soil and water. [ABSTRACT FROM AUTHOR]

Americans' concern about water quality has increased over the years. Indeed, several water issues made national news coverage during the past few years, such as lead in Flint, Michigan, algae blooms in Florida, and water quality at the Rio Olympics. In this study, we test two alternate paths of engagement relative to how people respond to water problems. First, we examine anxiety as a key variable that triggers active information seeking behaviors. Second, we look at hopelessness as an intervening variable that could explain why some people become disengaged with issues. Additionally, we test whether response efficacy moderates the relationships between perceiving a problem with water and these emotions. Using survey data collected during the fall of 2015, we examine the role of different emotions in increasing and decreasing active information seeking behaviors. [ABSTRACT FROM AUTHOR]

Flow-regulated discharges of water from control structures into estuaries result in hydrologic and water chemistry conditions that impact spatial and temporal variability in the structure and biomass of phytoplankton communities, including the potential for harmful algal blooms (HABs). The relationships between regulated Caloosahatchee River (i.e., C-43 Canal) discharges and phytoplankton communities in the Caloosahatchee Estuary and adjacent nearshore regions on the southwest coast of Florida were investigated during two study periods, 2009–2010 and 2018–2019. During periods of low to moderate discharge rates, when mesohaline conditions predominated in the estuary, and water residence times were comparatively long, major blooms of the HAB dinoflagellate species Akashiwo sanguinea were observed in the estuary. Periods of high discharge were characterized by comparatively low phytoplankton biomass in the estuary and greater influence of a wide range of freshwater taxa in the upper reaches. By contrast, intense blooms of the toxic dinoflagellate Karenia brevis in the nearshore region outside of the estuary were observed during high discharge periods in 2018–2019. The latter events were significantly associated with elevated levels of nitrogen in the estuary compared to lower average concentrations in the 2009–2010 study period. The relationships observed in this study provide insights into the importance of managing regulated discharge regimes to minimize adverse impacts of HABs on the health of the estuary and related coastal environments. [ABSTRACT FROM AUTHOR]

The Indian River Lagoon (IRL), a 156-mile-long estuary located on the eastern coast of Florida, experiences phytoplankton bloom events due to increased seasonal temperatures coupled with anthropogenic impacts. This study aimed to gather data on the toxicity to human cells and to identify secondary metabolites found in water samples collected in the IRL. Water samples from 20 sites of the IRL were collected during the wet and dry seasons over a three-year period. A panel of cell lines was used to test cytotoxicity. Hemagglutination, hemolysis, and inhibition of protein phosphatase 2A (PP2A) were also measured. Cytotoxic blooms were seen both in the south (Microcystis) and the north (Pyrodinium) of the IRL. Each toxin induced a consistent pattern of cytotoxicity in the panel of human cell lines assayed. During blooms, cytotoxicity due to a single type of toxin is obvious from this pattern. In the absence of blooms, the cytotoxicity seen reflected either a mixture of toxins or it was caused by an unidentified toxin. These observations suggest that other toxins with the potential to be harmful to human health may be present in the IRL. Moreover, the presence of toxins in the IRL is not always associated with blooms of known toxin-producing organisms. [ABSTRACT FROM AUTHOR]

This paper describes the results of 10 years of water quality monitoring in the Indian River Lagoon Florida, with special emphasis on the relationships between trends in climatic conditions and the distribution, composition, and abundance of the phytoplankton community. The Indian River Lagoon, which spans 220 km of Florida's east coast, is a region of particular concern because of the rapid rate of human development throughout the region and the hydrologically restricted character of the lagoon, which heightens the potential for algal bloom. Water sampling was carried out on a monthly to twice-monthly basis at six sites located in the northern and central lagoon. The 10-year study included both extended periods of below and above average rainfall. A number of ecologically distinct regions exist within the lagoon, which differ considerably in water exchange properties and watershed inputs. The northern lagoon is characterized by longer water residence times, lower phosphorus concentrations, higher nitrogen concentrations, and more stable salinity conditions than the central lagoon. Mean phytoplankton biovolumes were substantially higher at the sites in the northern lagoon than at the sites in the central lagoon, and algal blooms were more common and intense in the former region. Inter-annual patterns of phytoplankton biovolume were also different in the northern and central lagoon. In the northern lagoon, phytoplankton biovolumes were lowest during the drought period, from the autumn of 1998 to the spring of 2001. By contrast, algal bloom events in the central lagoon were not only less frequent but were not tied to periods of high rainfall. The most widespread and common bloom formers were the potentially toxic dinoflagellate Pyrodinium bahamense var. bahamense and two centric diatoms, Dactyliosolen fragilissimus and Cerataulina pelagica. Many of the biovolume peaks observed over the study period were attributable to these three species. The results of time series modeling of phytoplankton dynamics further highlighted the disparities between the two regions of the lagoon in terms of the suite of parameters that best predict the observed trends in the biomass of phytoplankton. Overall, the outcome of this initial modeling effort in the Indian River Lagoon suggests that time series approaches can help define the factors that influence phytoplankton dynamics. [ABSTRACT FROM AUTHOR]

The central eastern Florida shelf edge is a highly dynamic area that supports an important yet vulnerable deep-sea coral reefs ecosystem, the Oculina Coral Habitat Area of Particular Concern. Rapid and large short-terms (days to weeks) changes of bottom temperature (up to 9 °C) and p CO 2 (up to 180 μatm) were observed at the shelfbreak during a two-month (May 13-July 10, 2017) deployment of a lander package. An analysis suggests that these changes are the combined results of tides, the Gulf Stream meandering, and submesoscale eddies and filaments. The processes responsible for sub-tidal variability may include 1) the Gulf Stream frontal movements, 2) upwelling/downwelling of slope waters in association with the Gulf Stream variability, and 3) submesoscale processes and associated vertical movements. Satellite images also frequently show a narrow plume of elevated chlorophyll concentration that stretches from the coast northward up to >200 km along the Gulf Stream front during late spring and early summer. Our analysis indicates that these phytoplankton blooms in the plume are likely supported by the nutrient supply from the nutrients-rich slope waters to the shelf edge and subsequent local vertical mixing. Carbon export associated with these blooms can be an important food source to the Oculina corals. Upwelling of slope waters, on the other hand, will lead to increased CO 2 and reduced pH and aragonite saturation state along the shelf edge. Therefore, these dynamic processes may have strong impacts on the health and sustainability of the Oculina coral ecosystem. • Rapid short-terms changes of bottom temperature (up to 9 °C) and p CO 2 (up to 180 μatm). • A high chlorophyll plume stretches from the coast northward along the Gulf Stream front. • Short-terms variability are associated with GS meandering and submesoscale features. • The biogeochemical processes may have strong impacts on the deep coral ecosystem. [ABSTRACT FROM AUTHOR]

Benthic infaunal communities are important indicators of environmental change because they are comprised of organisms with limited mobility that respond rapidly to stress. As part of the Comprehensive Everglades Restoration Plan to restore natural water flows across the Florida peninsula, infaunal communities have been monitored since 2005 in relation to changing water quality and sediment characteristics at 9 sites in the southern Indian River Lagoon (IRL) and St. Lucie Estuary (SLE). Abiotic and biological differences separated the sites into 3 zones, with salinity and the abundance of fine-grained sediments emerging as major drivers of infaunal abundance, species richness and distribution. Degraded communities in the middle SLE were populated by opportunistic and pollution-tolerant taxa, while communities in the southern IRL were abundant and biodiverse. A total of 76 taxa and one-third of all infauna were lost across the three zones in 2016 and 2017, which was likely caused by harmful algal blooms and discharges of sediment and nutrientladen inland freshwater following an El Niño event and Hurricane Irma. This study highlights the importance of long-term monitoring to inform adaptive management practices and lays the groundwork for further analyses to understand how natural and anthropogenic stressors affect this dynamic system. [ABSTRACT FROM AUTHOR]

Seven species of seagrass have been found in the Indian River Lagoon (IRL), making it an unusually diverse location at the global scale. From 1994 to 2019, the lagoon-wide distribution of these species reflected variations in temperature, salinity, and the availability of light at depth, which were related to latitudinal differences in hydrology and hydrodynamics along the IRL. In general, species richness was higher near the four southern inlets, and fewer species were found in areas with longer residence times for water. At a finer scale, the distribution of species varied among depths, with the greatest number of species found at mid-depths (~0.4-0.9 m). Prior to 2011, these patterns remained relatively consistent for ~ 40 years, but several, intense and prolonged phytoplankton blooms disrupted them. The areal extent of all seagrasses decreased by over 50%, the offshore ends of canopies moved shoreward and shallower, distributions of species along gradients of latitude and depth were disrupted, and mean percent cover decreased. Major changes in distribution and abundance of seagrasses arose when salinity, temperature, and availability of light at depth exceeded limits derived for each species. These substantial and widespread changes engendered concerns for recovery or rehabilitation of seagrasses in the lagoon. [ABSTRACT FROM AUTHOR]

Florida's Gulf Coast is known as a retirement hotspot, with property values along the coast rising faster than almost anywhere else in the country. However, the coastal amenities that help boost prices, quickly turn to dis-amenities when there is a prolonged red tide bloom in the Gulf. Using a difference in differences hedonic valuation model, we examine six Southwestern Florida counties heavily impacted by four major algal bloom in the past 20 years. We find that affected properties within 1 mile of the coast sell for up to 30% less compared to similar homes sold during the same month in an unaffected county. With red tide predicted to increase in frequency and severity, mitigation of the effects must be paramount for these counties. Losses occur in almost all sectors of the economy, and for a state that relies so much on the health of the environment, declines in property values are a sign that action must be taken against these blooms. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) can be a natural hazard unlike anything else. Whereas a hurricane or tornado has a sudden and devastating impact to an area, an HAB can slowly impact people and the environment over the course of weeks, even months. Karenia brevis, more commonly known as red tide, can have this effect along the Gulf Coast of Florida, lasting for many weeks in a row, causing large-scale deaths in fish and other marine life, and respiratory issues in humans. These harmful effects can effect tourism, as visitors are not able to enjoy the coastlines Florida is famous for. We test a 6 county region, from Pinellas County, FL down to Collier County, FL, to determine the magnitude with which an additional day of red tide affects tourism-related revenues. Using a spline regression approach, we find that an additional day of red tide in a month with 17 days or more of red tide drives monthly lodging sector sales down by 1–2%, and restaurant sector sales down by 0.5–1%. As these blooms are increasing in frequency and persistency, it becomes of great importance to counties and effected businesses to control and mitigate red tide blooms as soon as possible. If not, losses and harmful effects will only continue to grow and become detrimental to the environment and economy. [ABSTRACT FROM AUTHOR]

Accounting for variation in prey mortality and predator metabolic potential arising from spatial variation in consumption is an important task in ecology and resource management. However, there is no statistical method for processing stomach content data that accounts for fine‐scale spatio‐temporal structure while expanding individual stomach samples to population‐level estimates of predation. Therefore, we developed an approach that fits a spatio‐temporal model to both prey‐biomass‐per‐predator‐biomass data (i.e. the ratio of prey biomass in stomachs to predator weight) and predator biomass survey data, to predict "predator‐expanded‐stomach‐contents" (PESCs). PESC estimates can be used to visualize either the annual landscape of PESCs (spatio‐temporal variation), or can be aggregated across space to calculate annual variation in diet proportions (variation among prey items and among years). We demonstrated our approach in two contrasting scenarios: a data‐rich situation involving eastern Bering Sea (EBS) large‐size walleye pollock (Gadus chalcogrammus, Gadidae) for 1992–2015; and a data‐limited situation involving West Florida Shelf red grouper (Epinephelus morio, Epinephelidae) for 2011–2015. Large walleye pollock PESC was predicted to be higher in very warm years on the Middle Shelf of the EBS, where food is abundant. Red grouper PESC was variable in north‐western Florida waters, presumably due to spatio‐temporal variation in harmful algal bloom severity. Our approach can be employed to parameterize or validate diverse ecosystem models, and can serve to address many fundamental ecological questions, such as providing an improved understanding of how climate‐driven changes in spatial overlap between predator and prey distributions might influence predation pressure. [ABSTRACT FROM AUTHOR]

Florida red tides occur annually due to proliferation of the marine dinoflagellate Karenia brevis, which produces neurotoxins known as brevotoxins. Inhalational exposure to brevotoxins usually results in upper airway symptoms only. Rarely does exposure lead to lower respiratory tract symptoms as in our case. We report a case of a 50-year-old man who presented with a 4-week history of dyspnea after exposure to the red tide. Computed tomography (CT) of the chest showed diffuse bilateral ground glass opacities and interstitial thickening. Bronchoalveolar lavage cultures and cytology were negative. The patient was started on steroids. Over the next few weeks, the patient's symptoms resolved. Repeat CT chest showed complete resolution of the ground glass opacities. Steroids were then tapered. Most patients who are exposed to algal blooms have self-limiting symptoms. Patients with asthma are particularly susceptible to worsening respiratory symptoms after exposure to brevotoxin aerosols. This case highlights that, in rare cases, exposure to red tide can results in severe lower respiratory tract symptoms. [ABSTRACT FROM AUTHOR]

Marine phytoplankton comprise the foundation of oceanic food webs and generate most of the Earth's oxygen. Of the many phytoplankton species in the ocean, a few dozen produce potent toxins, and at high concentrations can form what are called Harmful Algal Blooms (HABs) or "red tides" that can discolor marine waters. Managers and scientists have been monitoring coastal waters and shellfish resources for HABs and their toxins to ensure seafood safety and understand why blooms occur. This educational activity focuses on a prominent HAB species that causes paralytic shellfish poisoning (PSP). Students will learn about the importance of HABs and PSP, as well as how scientists collect and use data to understand and predict blooms. Students will plot data on HAB species collected by scientists over multiple years of sampling. Students will also plot results over time and across regions, report on observed patterns, and complete grade-appropriate calculations. Lastly, group discussion will focus on determining whether geographic patterns exist that might influence where shellfish beds are closed. This activity is timely given the widespread wildlife mortalities and beach closures due to Florida red tide in 2017-2018, as well as widely publicized dog deaths in 2019 caused by exposure to freshwater cyanobacteria (blue-green algae) blooms. [ABSTRACT FROM AUTHOR]

During the spring of 2011 an unprecedented "Super" algal bloom formed in the Indian River Lagoon (IRL), with Chlorophyll a (Chl a) concentrations over eight times the historical mean in some areas and lasted for seven months across the IRL. The European Space Agency's MEdium Resolution Imaging Spectrometer (MERIS) platform provided multispectral data at 665 and 708 nm, which was used to quantify the phytoplankton Chl a by fluorescence while minimizing the effects of other water column constituents. The three objectives were to: (1) calibrate and validate two Chl a algorithms using all available MERIS data of the IRL from 2002 to 2012; (2) determine the accuracy of the algorithms estimation of Chl a before, during, and after the 2011 super bloom; and (3) map the 2011 algal bloom using the Chl a algorithm that was proven to be effective in other similar estuaries. The chosen algorithm, Normalized Difference Chlorophyll Index (NDCI), was positively correlated with the in-situ measurements, with an R² value of 0.798. While there was a significant (62.9 ± 25%) underestimation of Chl a using MERIS NDCI, the underestimation appears to be consistent across the data and mostly in the estimations of lower concentrations, suggesting that a qualitative or ratio analysis is still valid. Analysis of the application of the NDCI processed MERIS data provided additional insights that the in-situ measurements were unable to record. The time series MERIS Chl a maps along with in-situ water quality monitoring data depicted that the 2011 IRL bloom started after a heavy rainfall in March 2011 and peaked in October 2011 after a decrease in temperature. The bloom collapse also coincided with heavy rainfall and rapidly decreasing temperatures and salinity through October to November 2011. [ABSTRACT FROM AUTHOR]

Tissue levels of mercury (Hg; total, organic) and selenium (Se) were assessed in juvenile lemon sharks ( Negaprion brevirostris) from Florida nearshore waters collected during a harmful algal bloom (HAB, brevetoxin) event and compared with sharks not exposed to HABs. In all sharks studied, total Hg levels in the muscle were generally present in a molar excess over Se (which may protect against Hg toxicity) and mean muscle Hg levels (0.34 $\upmu $g/g) exceed safe human consumption guidelines. While there was generally no difference in tissue Hg and Se levels following exposure of sharks to HABs, hepatic Hg levels were significantly lower (56% reduction) in the HAB-exposed sharks compared to controls. As Hg and HABs are globally increasing in scope and magnitude, further work is warranted to assess their interactions and biotic impacts within aquatic ecosystems, especially for a species such as the lemon shark that is classified as a near-threatened species by the International Union for the Conservation of Nature. [ABSTRACT FROM AUTHOR]

This article compares limnological attributes of two of the world’s largest shallow lakes—Lake Okeechobee in Florida, USA and Lake Taihu in P.R. China. Both the systems support an array of ecological and societal values including fish and wildlife habitat, public water supply, flood protection, and recreation. Both have extensive research programs, largely because of concern regarding the lakes’ frequent cyanobacterial blooms. By evaluating these systems together, we compare and contrast properties that can generally advance the understanding and management of large shallow lowland lakes. Because of shallow depth, long fetch, and unconsolidated mud sediments, water chemistry, and transparency in both the lakes are strongly influenced by resuspended sediments that affect light and nutrient conditions. In the central region of both the lakes, where depth is the greatest, evaluation of limiting factors by a trophic state index approach indicates that light most often limits phytoplankton biomass. In contrast, the more sheltered shoreline areas of both the lakes display evidence of nitrogen (N) limitation, which also has been confirmed in nutrient assays conducted in earlier studies. This N limitation most likely is a result of excessive levels of phosphorus (P) that have developed in the lakes due to high external loads over recent decades and the currently high internal P recycling. Comparisons of these lakes show that Lake Taihu has higher N than, similar total phosphorus (TP) and similar light conditions to that of Lake Okeechobee, but less chlorophyll a (CHL). The latter may be as a result of lower winter temperatures in Lake Taihu (around 5°C) compared to Lake Okeechobee (around 15°C), which could reduce phytoplankton growth and abundance through the other seasons of the year. In these systems, the important role of light, temperature, and nutrients in algal bloom dynamics must be considered, especially due to possible adverse and... [ABSTRACT FROM AUTHOR]

Ten Mile Creek (TMC) is a major tributary of the Indian River Lagoon (IRL), one of the largest and most ecologically diverse estuaries of the east coast of Florida. Recent algal blooms within the IRL have focused attention on the role of different watersheds playing in the supply of growth-limiting nutrients. The goal of this study was to determine the nutrient-limiting status of the TMC outflow, which is influenced by both agricultural input and urban development. Four laboratory experiments were conducted with water samples from TMC, adding different concentrations of phosphorus (P) and nitrogen (N) under controlled conditions. The results showed that turbidity and phytoplankton biomass (in terms of chlorophyll a concentration) in TMC water samples were responsive to N additions. Turbidity and phytoplankton biomass increased with addition of available N, but were not affected by addition of reactive P. The results indicate that available N is the limiting nutrient for the growth of phytoplankton in the TMC. [ABSTRACT FROM AUTHOR]

1. The effect of variability in rainfall on the potential for algal blooms was examined for the St Johns River in northeast Florida. Water chemistry and phytoplankton data were collected at selected sites monthly from 1993 through 2003. Information on rainfall and estimates of water turnover rates were used in the analyses of trends in phytoplankton biomass. 2. Major trends in rainfall and runoff within the lower St Johns River catchment over the 10-year study period were marked by both significant drought and flood periods. Autumn and winter rainfall patterns were strongly correlated with the range of Pacific sea surface temperature anomalies associated with El Niño events and La Niña periods. The effect of these major shifts in rainfall was evident in the strong relationship to replacement rates for water within the lower St Johns River. 3. The eutrophic status of the river was reflected in the high concentrations of nitrogen and phosphorus observed at all sampling sites, with total nitrogen concentrations up to 3100 μg L−1 and total phosphorus concentrations up to 180 μg L−1. 4. While it is clear that the high phytoplankton biomass and frequent blooms that characterize the freshwater portions of the lower St Johns River are fundamentally based on nutrient status, the expression of that potential was strongly correlated to water replacement rates, as revealed by the inverse relationship between phytoplankton biovolume increase and water turnover rate, with an R2 of 0.80 for the major bloom season. The sensitivity of algal blooms to rainfall patterns over the 10-year study period suggest that longer-term temporal and spatial shifts in rainfall, such as multi-decadal cycles and the global-warming phenomenon, will also influence the frequency and intensity of algal blooms. [ABSTRACT FROM AUTHOR]

The impacts of harmful algal blooms (HABs) on coastal businesses in the Ft. Walton Beach and Destin areas of northwest Florida were estimated for 1995-1999. Separate time-series models for the restaurant and lodging sectors revealed that HABs reduced restaurant and lodging revenues in the localized study area by $2.8 million and $3.7 million per month, respectively, which represents a 29% to 35% decline in average monthly revenues for each sector during months of red tide incidence. By comparison, a tropical storm was found to reduce monthly restaurant revenues by $0.5 million, and each inch of rainfall reduced revenues an additional $41,000. Adverse weather was not found to affect the lodging sector. While the estimates are conservative given the resolution of data, the magnitude of effects indicate that coastal communities have suffered significant revenue losses due to HABs and that these losses are larger than caused by other environmental events. [ABSTRACT FROM AUTHOR]

Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension, at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column transparency, suspended solids, and total P (TP). In summer there are diurnal changes in TP associated with afternoon winds, and in winter, when strong winds occur for multiple days, monthly average TP remains high compared to summer. The magnitude of daily and seasonal TP changes can exceed 100 μg l−1. Hurricanes and tropical storms also cause extreme changes in TP that are superimposed on seasonal dynamics. When a hurricane passed 80 km south of the lake in October 1999, mean pelagic TP increased from 88 to 222 μg l−1. During large resuspension events, light attenuation is substantially increased, and this influences the biomass and spatial extent of submerged plants, as well as water column TP. In Lake Okeechobee, TP concentrations typically are ∼20 μg l−1 when submerged plants are dense, and soluble reactive P concentrations are reduced below detection, perhaps by the periphyton and plant uptake and by precipitation with calcium at high pH. In contrast, TP exceeds 50 μg l−1 when submerged plants and periphyton are absent due to prolonged deep water, and phytoplankton biomass and algal bloom frequency both are increased. In Lake Okeechobee and other large shallow lakes, complex models that explicitly consider wind-wave energy, hydrodynamics, and sediment resuspension, transport, and key biological processes are needed to accurately predict how lake water TP will respond to different management options. [ABSTRACT FROM AUTHOR]

Recent increases in global urea usage, including its incorporation in slow-release fertilizers commonly used in lawn care in Florida, have the potential to alter the form and amount of nitrogen inputs to coastal waters. This shift may, in turn, impact phytoplankton community diversity and nutrient cycling processes. An autonomous water quality monitoring and sampling platform containing meteorological and water quality instrumentation, including urea and phycocyanin sensors, was deployed between June and November of 2009 in Sarasota Bay, Florida. This shallow, lagoonal bay is characterized by extensive and growing urban and suburban development and limited tidal exchange and freshwater inputs. During the monitoring period, three high-biomass (up to 40 µg chlorophyll-a·L−1) phytoplankton blooms dominated by picocyanobacteria or picoeukaryotes were observed. Each bloom was preceded by elevated (up to 20 μM) urea concentrations. The geolocation of these three parameters suggests that "finger canals" lining the shore of Sarasota Bay were the source of urea pulses and there is a direct link between localized urea inputs and downstream picoplankton blooms. Furthermore, high frequency sampling is required to detect the response of plankton communities to pulsed events. [ABSTRACT FROM AUTHOR]

Microcystins (MC) and nodularin (NOD) are toxins released by cyanobacteria during harmful algal blooms. They are potent inhibitors of protein phosphatases 1 and 2A (PP1 and PP2A) and cause a variety of adverse symptoms in humans and animals if ingested. More than 250 chemically diverse congeners of MCs have been identified, but certified reference materials are only available for a few. A diagnostic test that does not require each reference material for detection is necessary to identify human exposures. To address this need, our lab has developed a method that uses an antibody to specifically isolate MCs and NOD from urine prior to detection via a commercially available PP2A kit. This assay quantitates the summed inhibitory activity of nearly all MCs and NOD on PP2A relative to a common MC congener, microcystin-LR (MC-LR). The quantitation range for MC-LR using this method is from 0.050–0.500 ng/mL. No background responses were detected in a convenience set of 50 individual urines. Interday and intraday % accuracies ranged from 94%–118% and relative standard deviations were 15% or less, meeting FDA guidelines for receptor binding assays. The assay detected low levels of MCs in urines from three individuals living in close proximity to harmful algal blooms (HABs) in Florida. [ABSTRACT FROM AUTHOR]

Ecosystem service flows may change or disappear temporarily or permanently as a result of environmental changes or ecological disturbances. In coastal areas, ecological disturbances caused by toxin-producing harmful algae blooms can impact flows of ecosystem services, particularly provisioning (e.g., seafood harvesting) and cultural services (e.g., recreation). This study uses a random utility model of recreational boating choices to simulate changes in the value of cultural ecosystem services provided by recreation in coastal ecosystems resulting from prolonged ecological disturbances caused by harmful algae blooms. The empirical application relies on observed trips to 35 alternative boat access ramps in Lee County, an important marine access destination in southwest Florida. Results indicate that reduced boating access from harmful algae blooms may have resulted in losses of $3 million for the 2018 blooms, which lasted from the end of June to the end of September. [ABSTRACT FROM AUTHOR]