Harmful Algal Blooms

Abstract

Phytoplankton are free-floating plants found in marine and freshwaters that through their photosynthetic growth form the base of the aquatic food chain. A small subset of the phytoplankton may be harmful to human health or to human use of the ecosystem. The species that cause harm are now widely referred to as 'Harmful Algae' with the term 'Harmful Algal Bloom' (HAB) commonly being used to describe their occurrence and effects. In terms of human health, the most important consequence is the production, by some species, of biotoxins. Typically, biotoxin-producing phytoplankton species exist at relatively low densities (c. few hundred or thousand of cells per litre) with the toxins becoming concentrated in the flesh of organisms (particularly bivalve molluscs) that filter feed on phytoplankton. In most cases, there are no adverse effects to these primary consumers, but this concentrating mechanism creates a risk to health if the shellfish are consumed by humans. In this review, we provide an overview of the mechanisms through which marine phytoplankton may cause harm to humans in terms of heath, and the negative effects on the use of ecosystem services. Subsequently, we consider HAB issues in the area we are most familiar with: UK coastal waters. Finally, the methodologies used to safeguard human health from HAB-generated syndromes are discussed. PhytoplanktonPhytoplankton is the collective name for the tiny organisms in lakes and seas. The word derives from the Greek phyton (plant) and planktos (wandering), 95 Issues in Environmental Science and Technology, 33 Marine Pollution and Human Health Edited by R.E. Hester and R.M. Harrison

Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea

“…Shelf sea phytoplankton are therefore particularly important for global carbon cycling [ 3 ] and also form the base of marine food webs underpinning shelf sea fisheries and aquaculture [ 4 ]. Coastal blooms of harmful phytoplankton species also pose a threat to fishing and aquaculture industries as well as to tourism and human health [ 5 , 6 ]. The EU Marine Strategy Framework Directive (MSFD) requires member states to assess if their plankton communities achieve ‘ Good Environmental Status ’ by 2020.…”

The Relationship between Phytoplankton Distribution and Water Column Characteristics in North West European Shelf Sea Waters

“…Those authors that have investigated the open shelf have considered the biogeography of dinoflagellates [23]–[25], the role of localized features [26]–[28], productivity in specific locations [27], [29] or the analysis of continuous plankton recorder (CPR) data [30], [31]. While significant numbers of harmful phytoplankton events have been recorded in coastal regulatory monitoring in the region [32]–[34] these observations are typically made in isolation to other environmental variables, and hence cause and effect are not easily related.…”

Nitrogen dynamics and phytoplankton community structure: the role of organic nutrients

“…It is of note that P. minimum is also an important HAB species Glibert et al 2012), although its occurrence was comparatively short-lived. Some Pseudo-nitzschia species can produce the neurotoxin domoic acid which, when concentrated by filter-feeding shellfish and is ingested by humans, can result in Amnesic Shellfish Poisoning (Davidson et al 2011). The Scottish west coast is a region of shellfish aquaculture and Pseudo-nitzschia are actively monitored.…”