Overview of key phytoplankton toxins and their recent occurrence in the North and Baltic Seas

Abstract

The frequency and intensity of harmful algal blooms (HABs) appear to be on the rise globally. There is also evidence of the geographic spreading of toxic strains of these algae. Consequently, methods had to be established and new ones are still needed for the evaluation of possible hazards caused by increased algal toxin production in the marine food chain. Different clinical effects of algae-related poisoning have attracted scientific attention; paralytic shellfish poisoning, diarrhetic shellfish poisoning, and amnesic shellfish poisoning are among the most common. Additionally, cyanobacteria (blue-green algae) in brackish waters often produce neurotoxic and hepatotoxic substances. Bioassays with mice or rats are common methods to determine algal and cyanobacterial toxins. However, biological tests are not really satisfactory because of their low sensitivity. In addition, there is growing public opposition to animal testing. Therefore, there has been increasing effort to determine algal toxins by chemical methods. Plankton samples from different European marine and brackish waters were taken during research cruises and analyzed on board directly. The ship routes covered marine areas in the northwest Atlantic, Orkney Islands, east coast of Scotland, and the North and Baltic seas. The first results on the occurrence and frequency of harmful algal species were obtained in 1997 and 1998. During the 2000 cruise an HPLC/MS coupling was established on board, and algal toxins were measured directly after extraction of the plankton samples. In contrast to earlier cruises, the sampling areas were changed in 2000 to focusing on coastal zones. The occurrence of toxic algae in these areas was compared to toxin formation during HABs in the open sea. It was found that the toxicity of the algal blooms depended on the prevailing local conditions. This observation was also confirmed by monitoring cyanobacterial blooms in the Baltic Sea. Optimal weather conditions, for example, during the summers of 1997 and 2003, favored blooms of cyanobacteria in all regions of the Baltic. The dominant species regarding the HABs in the Baltic was Nodularia spumigena. However, in addition to high concentrations of Nodularia spumigena in coastal zones, other blue-green algae are involved in bloom formation, with changes in plankton communities influencing both toxin profiles and toxicity.

Species-specific responses of a cyanobacteriadominated phytoplankton community to artificial nutrient limitation in the Baltic Sea

“…Huge late-summer surface accumulations of filamentous cyanobacteria (Kahru et al 1994(Kahru et al , 2000 have aroused considerable public concern, especially as several of the common Baltic Sea species (Nodularia, Anabaena, Microcystis) are toxic (Willén & Mattsson 1997, Luckas et al 2005). Based on the N 2 -fixing capacity of several species, effective P-discharge reductions have been advocated to control the offshore blooms, at the expense of N reductions.…”

“…Several commonly occurring cyanobacteria (N. spumigena, Anabaena spp., Microcystis spp.) may produce toxins and pose health risks for humans and livestock (Luckas et al 2005). Aphanizomenon flos-aquae (L.) Ralfs, found in lakes around the Baltic Sea, has often been confirmed to be toxic (Willén & Mattsson 1997), whereas Aphanizomenon isolates from the Baltic Sea have not (Lehtimäki et al 1997), even though there are no consistent morphological differences between the 2 (Laamanen et al 2002).…”

Preliminary survey of potentially harmful dinoflagellates in Nigeria´s coastal waters.

“…Scientists in some coastal countries have taken the lead in the monitoring of HAB species in their respective countries. Some of such workers include PAuley et al (1993), Aune et al (1995), Belin et al (1995), jAcKSon & SilKe (1995, PiTcHer & mATTHeWS (1996), BoeScH et al (1997), mAcKenzie et al (1996), yAmAmoTo & yAmASAKi (1996), lucKAS et al (2005 and TAng et al (2006). If harmful dinoflagellates are detected early enough in coastal waters, it might pave the way for prompt precautionary measures (which can help in the prevention, control and/ or mitigation of their impacts on the human population) to be taken by public health officials.…”

Sources, factors, mechanisms and possible solutions to pollutants in marine ecosystems

“…The occurrence, abundance and geographical distribution of toxin-producing algae or cyanobacterial blooms have substantially increased during the last few decades, because of increased anthropogenic input of organic matter pollution and nutrients as well as global warming (Van Dolah, 2000;Phlips et al, 2004;Yan and Zhou, 2004;Glibert et al, 2005;Luckas et al, 2005;McCarthy et al, 2007;Moore et al, 2008;Mostofa et al, 2013bMostofa et al, , 2013d. Algal toxins or red tide toxins produced during algal blooms in surface waters are responsible for physiological, ecological and environmental adverse effects (Hayman et al, 1992;Falconer, 1993;Bricelj and Lonsdale, 1997;Pilotto et al, 1999;Glibert et al, 2001;Fleming et al, 2005;Imai et al, 2006;Álvarez-Salgado et al, 2007;Backer et al, 2005Backer et al, , 2008Erdner et al, 2008;Imai and Kimura, 2008;Moore et al, 2008;Prince et al, 2008;Sekiguchi and Aksornkoae, 2008;Castle and Rodgers Jr., 2009;Yates and Rogers 2011;Mostofa et al, 2013bMostofa et al, , 2013d):…”