High biomass algal blooms tend to occur when transport and mixing time scales exceed phytoplankton growth time scale, resulting in many detrimental effects to the ecosystem and possibly to humans. In order to implement appropriate management strategies to overcome the nuisance of such blooms, it is essential to study the hydrodynamic mechanisms influencing horizontal transport and mixing rates that in turn determine locations conducive to excessive phytoplankton growth. An integrated approach consisting of a theoretical method, a field experiment, historical data and three-dimensional hydrodynamic and ecological modeling was used to understand the physical processes affecting high biomass blooms of the diatom Aulacoseira sp. in the shallow upper Río de la Plata estuary (Argentina-Uruguay). Two high biomass blooms events impacted the drinking water treatment plants of the city of Buenos Aires (Argentina) causing a disruption to normal operation of the plants and risked the drinking water supply to more than 10 million people. Firstly, it was shown that the shallow nature of the estuary tends to direct the flow towards the deeper shipping channels, creating stagnation zones near the Argentinean boundary. Energy levels available for mixing were higher near the Uruguayan boundary and center of the estuary than in the stagnant region along the Argentinean margin. High discharge regimes were shown to also intensify mixing, as opposed to periods of low inflow rates. Secondly, it was demonstrated that these stagnation zones, combined with the transport of algae cells from contributing inflows, and low concentrations of suspended solids in the water column were the main drivers for the occurrence of two high biomass bloom events. Finally, three mitigation strategies were explored to decrease the effects of high biomass algae blooms on the drinking water intakes. An automated real-time and forecast management system was successfully implemented in the Río de la Plata estuary to monitor and predict the occurrence of Aulacoseira sp. near the drinking water intakes. Two engineering solutions were proposed and the results demonstrated that extending the drinking water intakes further offshore or placing groynes near the drinking water intakes would decrease the concentration of Aulacoseira sp. by up to 50 % and 40 % respectively.

Environmental problems in coastal ecosystems can sometimes be attributed to excess nutrients flowing from upstream watersheds into estuarine settings. This nutrient over-enrichment can result in toxic algal blooms, shellfish poisoning, coral reef destruction, and other harmful outcomes. All U.S. coasts show signs of nutrient over-enrichment, and scientists predict worsening problems in the years ahead. Clean Coastal Waters explains technical aspects of nutrient over-enrichment and proposes both immediate local action by coastal managers and a longer-term national strategy incorporating policy design, classification of affected sites, law and regulation, coordination, and communication. Highlighting the Gulf of Mexico's "Dead Zone," the Pfiesteria outbreak in a tributary of Chesapeake Bay, and other cases, the book explains how nutrients work in the environment, why nitrogen is important, how enrichment turns into over-enrichment, and why some environments are especially susceptible. Economic as well as ecological impacts are examined. In addressing abatement strategies, the committee discusses the importance of monitoring sites, developing useful models of over-enrichment, and setting water quality goals. The book also reviews voluntary programs, mandatory controls, tax incentives, and other policy options for reducing the flow of nutrients from agricultural operations and other sources.

The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.

This dissertation examines the effect of transport on coastal productivity and harmful algal blooms in coastal upwelling systems in three parts, using the Pacific Northwest coastal ocean (also referred to as the Northern California Current System) and the greater California Current System (CCS) as a case study. These three studies utilize a combination of observations and model output. Chapter 2 investigates the effects of upwelling variability and large-scale advection on slope and shelf water properties in the Northern CCS using both Eulerian and Lagrangian analyses in a 7-year ROMS hindcast model. Results suggest that variability in the depth of the California Undercurrent as well as in alongshore local and remote wind stress are responsible for about 50% of shelf bottom water variability, and that the shelf and slope experience similar large-scale alongcoast advection patterns. These results were then combined with observations of dissolved oxygen and dissolved inorganic carbon concentrations to approximate the relative effects of variability in upwelling and in large-scale advection on shelf and slope water properties. Next, in Chapter 3, we examine the relationship between phytoplankton productivity, wind patterns, and retention in the Northern and Central CCS using chlorophyll concentration and wind stress derived from satellite observations, as well as particle tracking experiments conducted in the same ROMS model. Results from this analysis suggest that while there is a dome-shaped relationship between mean chlorophyll concentration and wind stress for the whole system, the Central and Northern CCS have significantly different relationships. However, results from the particle tracking experiments suggest that the effect of wind intermittency on retention is minimal in the Northern CCS on a 1° latitude-wide scale. Lastly, we present a revised hypothesis to describe the relationship between chlorophyll concentration and wind stress in the CCS that includes the influence of non-upwelling-derived nutrients in the Northern CCS. Finally, in Chapter 4 we use similar particle tracking experiments combined with observations of Pseudo-nitzschia cells at Pacific Northwest coastal beaches and meridional wind stress to test whether the model reproduces the observed beaching patterns of Pseudo-nitzschia cells. With the goal of improving how the model is used to forecast beaching events, we test a suite of beaching criteria as well as two resolutions of the model. Results suggest that allowing for multiple coastal proximity events as well as using the loosest beaching criteria resulted in the most successfully simulated HAB events in the medium-resolution version of the model, and that the high-resolution version of the model performed best overall. All together, these three studies help elucidate the numerous effects that transport, both positive and negative, can have on the biology of the coastal ocean.

The study of estuaries and coasts has seen enormous growth in recent years, since changes in these areas have a large effect on the food chain, as well as on the physics and chemistry of the ocean. As the coasts and river banks around the world become more densely populated, the pressure on these ecosystems intensifies, putting a new focus on environmental, socio-economic and policy issues. Written by a team of international expert scientists, under the guidance of Chief Editors Eric Wolanski and Donald McClusky, the Treatise on Estuarine and Coastal Science, Ten Volume Set examines topics in depth, and aims to provide a comprehensive scientific resource for all professionals and students in the area of estuarine and coastal science Most up-to-date reference for system-based coastal and estuarine science and management, from the inland watershed to the ocean shelf Chief editors have assembled a world-class team of volume editors and contributing authors Approach focuses on the physical, biological, chemistry, ecosystem, human, ecological and economics processes, to show how to best use multidisciplinary science to ensure earth's sustainability Provides a comprehensive scientific resource for all professionals and students in the area of estuarine and coastal science Features up-to-date chapters covering a full range of topics

Harmful algal blooms (HABs) - blooms that cause fish kills, contaminate seafood with toxins, or cause human or ecological health impacts and harm to local economies - are occurring more often, in more places and lasting longer than in past decades. This expansion is primarily the result of human activities, through increased nutrient inputs and various aspects of climate change. The Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) programme promoted international collaboration to understand HAB population dynamics in various oceanographic regimes and to improve the prediction of HABs. This volume introduces readers to the overarching framework of the GEOHAB programme, factors contributing to the global expansion of harmful algal blooms, the complexities of HABs in different habitats, and the forward-looking issues to be tackled by the next generation of GEOHAB, GlobalHAB. The programme brought together an international team of contributing scientists and ecosystem managers, and its outcomes will greatly benefit the international research community.