Graciela Ferrari, National Direction of Aquatic Resources, Constituyente 1497, CP 11200. Montevideo. Uruguay; E-mail: gferrari@dinara.gub.uy
Abstract
An apparent increment in frequency and toxic events caused by algae species has been observed on a global scale. On the Southwestern Atlantic Ocean coast has not been out of this situation. In this zone, PSP, DSP, ASP and microcystin occur from Tierra del Fuego to the north of Brazil. The first report of PSP was detected in Peninsula Valdés (Argentina 42° S) in 1980 after a dramatic episode occurred where two members of the crew of the ship Constance died after eating contaminated mussels and Alexandrium tamarense was registered. Coincidentally, 60 persons were affected with neurotoxic symtomatology in Uruguay, PSP reached high levels, but the specie was not identified. After this episode several outbreaks of A. tamarense were recorded overtaking Brazilian waters and others dinoflagellates PSP producers: A. catenella and G. catenatum were identified. A. tamarense recurrently blooms in south Argentina and have been suggested that northwards currents spread A. tamarense reaching south Brazilian waters. Every year A. catenella blooms in the Tierra del Fuego fjords and shellfish toxicity is registered currently since 1992. PSP outbreaks in Uruguay were also associated with Gymnodinium catenatum during summer time since 1991 and in coastal sediments high cyst densities of this species were reported. This species was, recently in 1998, observed in Santa Catarina State coast (27° S).
PSP have also been detected in the freshwater cyanobacteria Cylindroespermopsis raciborskii, but no human intoxication was detected in Brazil.
In 1990 several persons showed gastrointestinal distress and diarrhea after eating mussels in Florianopolis (Brazil 27° S) and in Uruguay in 1991. In both countries, plankton analysis and mouse bioassay supported the evidence of DSP and Dinophysis acuminata. In Argentina D. acuminata and D. forti are present but no toxicity was detected until 1999 where 40 persons were intoxicated in Patagonia (Argentina 40° S) and was confirmed the Prorocentrum lima in the plankton and DSP in mussels.
Recently, the most relevant was the detection of ASP in Mar del Plata (Argentina 38° S) in winter 2000. The dominant specie was Pseudo-nitschia australis and the toxin was registered in mussel and in fish Engraulis anchoita and two massive mortality episodes of sea birds were reported.
Harmful cyanobacteria blooms are a recurrent phenomenon that have been increasing last years. Several Microcystis aeruginosa blooms in Lagoa dos Patos estuarine, Brazil (30° S) were registered with microcystin detections. The most shoking case was in Pernambuco State in Brazil in 1996 when 60 person died in an haemodialysis centre. After that, it was introduced new freshwater reglamentation for human consumption that include microcystin levels.
Microcystis aeruginosa commonly blooms in summer periods in Uruguay. Last February 2001, a very extensive bloom in different aquatic systems and in the coast of Río de la Plata was registered. This episode was accompanied by other cyanobacteria species: M. novacekii, M. flos-aquae, M. wessenbergii, Anabaena circinalis and A. cf. spiroides that have not been registered in the coast before This phenomenon caused public impact, fish mortality and problems in drinkable water. Many people had skin problems, however neither of them were reported to the Public Health authorities or to the Toxicity centre. The authorities of the City Hall of Montevideo closed the beaches affected by the algae and warned about harmful effects. The National Direction of Aquatic Resources authorities recommended not to consume fish in affected areas.
Chattonela sp. and Heterosigma akashiwo represent a risk at intensive shrimp cultures and shellfish cultures, in Santa Catalina, Brazil.
Argentina has a National Monitoring program of mussels toxicity in each coastal province throughout regional Laboratories and one fixed station in Mar del Plata. Brazil had a pilot monitoring during one year, but not National Monitoring Program was established. However, Uruguay, has a regular National Monitoring Program in mussels toxicity and toxic phytoplankton.
A Regional Science Planning workshop on harmful algal blooms in South America supported by IOC is carried out every two years and the countries have a information network for toxic events. The working group identifies the regional needs, the harmful algae species, the food regulation systems for marine toxins, the research priorities and promote contacts and information exchange between regional experts involved in the control and researcher.