Harmful algal blooms: causes, impacts and detection

Abstract

Blooms of autotrophic algae and some heterotrophic protists are increasingly frequent in coastal waters around the world and are collectively grouped as harmful algal blooms (HABs). Blooms of these organisms are attributed to two primary factors: natural processes such as circulation, upwelling relaxation, and river flow; and, anthropogenic loadings leading to eutrophication. Unfortunately, the latter is commonly assumed to be the primary cause of all blooms, which is not the case in many instances. Moreover, although it is generally acknowledged that occurrences of these phenomena are increasing throughout the world's oceans, the reasons for this apparent increase remain debated and include not only eutrophication but increased observation efforts in coastal zones of the world. There is a rapidly advancing monitoring effort resulting from the perception of increased impacts from these HABs, manifested as expanding routine coastal monitoring programs, rapid development and deployment of new detection methods for individual species, toxins, and toxicities, and expansion of coastal modeling activities towards observational forecasts of bloom landfall and eventually bloom prediction. Together, these many efforts will provide resource managers with the tools needed to develop effective strategies for the management and mitigation of HABs and their frequently devastating impacts on the coastal environment.

Mapping phytoplankton blooms in deep subalpine lakes from Sentinel-2A and Landsat-8

“…In particular, cyanobacteria blooms are often characterized by complex dynamics in the vertical layers, when the taxa involved are capable of rapid vertical migration (Walsby et al, 1997). The typical dynamics of cyanobacterial blooms, which also have a very fast replication rates, make it difficult to perform a quantitative monitoring of number of cells and spatiotemporal distribution as surface blooms can appear and disappear quickly, often within few hours (Sellner et al, 2003;Agha et al, 2012). The cyanobacteria principally responsible for forming blooms are mainly gas-vacuolate species.…”

Molecular insights into a dinoflagellate bloom

“…The abundance and distribution of phytoplankton in shallow estuarine systems are greatly affected by physical, chemical and biological factors (Sellner et al, 2003). Optimal temperature, salinity and light conditions may vary among bloom-forming algal species (Smayda, 1997;Litaker et al, 2002).…”

Change characteristics of DSi and nutrition structure at the Yangtze River Estuary after Three Gorges Project impounding and their ecological effect

“…On the contrary, lack of one nutrient element will inhibit biological growth and reproduction. Excessive content of one element or imbalanced nutrition structure will affect plankton population structure signifi cantly and even will cause red tide (Sellner et al 2003). At the Yangtze River Estuary, nutrition proportions and some physical conditions may be more important to eutrophication control compared to single nutrition load with concentration (Sharp 2003).…”