Global and local factors driving the phenology of Alexandrium minutum (Halim) blooms and its toxicity

Abstract

The dinoflagellate Alexandrium minutum is a toxic bloom-forming species distributed worldwide. The mechanisms driving and promoting the species blooms and their toxicity are studied and presented here. Most previously published work focuses on local and/or short-term scales. In this study, a broad temporal and spatial approach is addressed using time series covering several sites over several years and combining environmental variables and A. minutum abundances from the French English Channel - Atlantic coasts. Data were explored by means of phenology and threshold analysis. The A. minutum bloom characteristics are defined. Only one bloom per year is measured and it may reach more than a million of cells L. Bloom period extends from April to October and the bloom length ranges from two weeks to six months. In the ecosystems studied, water temperature and river flow, as regional and local factors respectively, are the main environmental drivers influencing the magnitude, growth rate and length of the blooms. Bloom toxicity is linked to the bloom maximum abundance and river flow. This work provides new knowledge for further managing tools for A. minutum blooms in the ecosystems studied.

A review of the global distribution of Alexandrium minutum (Dinophyceae) and comments on ecology and associated paralytic shellfish toxin profiles, with a focus on Northern Europe

“…In many regions experiencing blooms these accumulations tend to occur from spring, into the summer months, March to August in the Northern Hemisphere (Lassus et al 2004, Blanco et al 2009, Le Bec et al 2016, Guallar et al 2017 and September to February in the Southern Hemisphere (Chang et al 1997, Hwang et al 1999, Bayl on et al 2015. There are some cases of winter blooms of this species, with most of these reported in the Northern Mediterranean , Alacid et al 2017.…”

“…, Guallar et al. ) and September to February in the Southern Hemisphere (Chang et al. , Hwang et al.…”

“…, Guallar et al. ), which represents a well‐studied area both geographically and temporally. The limited known distribution in some areas may be as a result of a lack of suitable conditions or it could simply be that surrounding areas have not received sufficient attention from research or monitoring groups to determine the presence or absence of A. minutum .…”

“…Several of these areas where occurrence is limited in range represent understudied regions, in some cases comprehensive plankton surveys are being carried out for the first time. In other parts of the world it has been identified at several locations, such as multiple sites around northern Europe (Elbrachter 1998, Nehring 1998, Godhe et al 2001a, Hansen et al 2003, Touzet et al 2007a, Brown et al 2010, Guallar et al 2017, which represents a well-studied area both geographically and temporally. The limited known distribution in some areas may be as a result of a lack of suitable conditions or it could simply be that surrounding areas have not received sufficient attention from research or monitoring groups to determine the presence or absence of A. minutum.…”

Modelling paralytic shellfish toxins (PST) accumulation in Crassostrea gigas by using Dynamic Energy Budgets (DEB)

“…were reported in the Mediterranean sea (Honsell et al, 1996). Since then, this genus has been increasingly incriminated for other events worldwide (Anderson, 1989;Hallegraeff, 1993;Cembella, 1998;Guallar et al, 2017). A. minutum synthesizes paralytic shellfish toxins (PST), including STX and its derivatives, that can be bioaccumulated throughout the food chain via feeding.…”