**4. Harmful algal bloom**

The toxins produced by toxic algal blooms (HAB - Harmful Algal Bloom) have the ability to bioconcentrate through the food chain. Therefore, humans, like many other animals that occupy the highest scales of this chain are vulnerable to the adverse effects of these toxins [3, 38]. The greatest risk of poisoning and gastrointestinal infections are linked to sea food consumption, especially of bivalve mollusks (mussels and oysters), because they are filter feeders, which makes these organisms accumulate large amounts of HABs. Bathers are also exposed to the effects of blooms of toxic algae by ingestion and inhalation of "spray" produced by the action of breaking waves containing HABs [39].

268 Biodiversity Conservation and Utilization in a Diverse World

The Brazilian coast present 8,698 kilometers long of extension, covering about 514,000 square kilometers. The heterogeneity and vulnerability of this coastal region is obstacle for environmental management, principally due to the proportion of the population living in this environment (18%). As an example, 16 out of 28 metropolitan regions in Brazil are located along the coast. Coastal erosion is particularly a phenomenon that results in an elevated risk to the large number of people inhabiting coastal areas along the Brazilian coast [35, 36]. Despite of the widespread range or coastal eroded regions, the configuration of the magnitude of the disasters are not equally distributed. Environmental influences (e.g. wind, wave and wave partners and trends) have been identified as the developer to seashore erosion, but human intervention in the morphodynamic of river mouth or sedimentary flux has influenced such disasters. In Atafona beach, São João da Barra (northern coast of Rio de Janeiro state) the coastal erosion has dramatically impacted the region [37]. The landward advance of the sea has already caused several consequences for local residents, including habitation loss, economical impacts, and historic and touristic impairments. In places where before there were houses and streets, and an established local commerce, is now part of coastal water or shows a scenario of destruction: about 400 houses in 16 blocks away have been demolished by the power of the waves (Figure 2). Atafona is located at the south side of the Paraíba do Sul River, the main river of the Rio the Janeiro state. The environmental variables and anthropogenic influences are thought to trigger the disasters that have been observed since 1950 [37]. The reduction of the fluvial discharge, as result of the human activities along Paraíba does Sul River, has contributed to the degradation of the coastal zone in Atafona. The sea level rise triggered by the climate change probably may influence increasing the impact in the coastal.

**Figure 2.** Images showing the coastal erosion caused by the sea energy in Atafona, São João da Barra,

The toxins produced by toxic algal blooms (HAB - Harmful Algal Bloom) have the ability to bioconcentrate through the food chain. Therefore, humans, like many other animals that

northern Rio de Janeiro state, Brazil. Downloaded from: http://viafanzine.jor.br/site\_vf/pag/1/na\_terra\_fotos.htm

**4. Harmful algal bloom** 

Worldwide, sea weed toxins have been associated with cases of human poisoning and animals fatalities [38, 40]. Moreover, massive blooms of toxic and nontoxic algae can cause sharp decrease of oxygen (hypoxia) in place of occurrence, resulting in massive death of marine life and affecting recreation, fish commerce, tourism and public health [38]. From 5000 species of phytoplankton, about 300 occur in massive blooms and slightly more than 80 are known to be toxic [3, 41]. The HAB species are classified as toxin producers (can contaminate sea food or kill fish) and as high biomass producers (can cause hypoxia or anoxia and die off of marine life, when reach high concentrations) [42]. The "toxic producers" HAB species can cause shellfish poisonings and potential impacts on public health, and the "high biomass produces" are thought to promote massive mortalities of fish and reductions in yields in deteriorated environments.

Some blooms of toxic algae can persist in the environment due to the inhibiting power of the toxins on the growth of other phytoplankton species, or reduce the predation of zooplankton. The human poisonings caused by exposure to HABs cause serious problems to human health, which can lead to death or produce sequels. However, it is not uncommon physicians in coastal regions, where most cases occur, erroneously diagnose the symptoms of poisoning, or attributed other factors to them [43]. In addition, there is evidence that colorectal cancer is strongly associated with the ingestion of biotoxins produced by marine microalgae through the consumption of bivalve mollusks [44]. There are five recognized types of poisoning caused by ingestion of HAB: paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), diarrheic shellfish poisoning (DSP), amnesic shellfish poisoning (ASP) and ciguatera poisoning (CFP) [1, 3, 4, 6, 38, 39]. Different from the other four types of HAB poisoning the CFP is caused by the ingestion of reef fishes contaminated by toxins produced by dinoflagellates. Therefore the toxin can enter in the food chain and impact top predators, such as humans [42].

Although there is record of HABs before the transformation of coastal ecosystems by anthropogenic activities, in recent decades has increased dramatically the number of problems associated with HABs around the globe. However, part of this growth is associated with the growth of environmental monitoring. A potential route of spread of these organisms lies in the transport of ballast water in ships. In addition, bivalve mollusks commercially introduced for aquaculture in the countries can also carry the organism in various ways [45]. Global environmental changes such as the destruction of reefs, nutrient enrichment of coastal waters by nitrogen and phosphorus, as well as global climate change, may serve to explain the increase of red tides reported worldwide, as well as the growth of human diseases related with exposure to marine toxins or associated with the events. Also, cholera outbreaks have been associated with HABs from the knowledge that marine

copepods are capable of carrying the bacteria *Vibrio cholerae*, feed of algal blooms. Therefore, these blooms can lead to spread of cholera and outbreaks associated with the frequency of flooding and extreme events [46]. Shuval [40] estimated that marine biotoxins associated mainly with blooms of toxic algae cause an estimated 100,000 to 200,000 cases of severe poisoning annually worldwide and approximately 10,000 to 20,000 deaths and a similar number of very severe cases with neurological sequel, such as paralysis. Furthermore, HABs events can produce mass deaths of marine organisms and cause heavy economic losses, mainly in the extractive fishing, aquaculture and tourism [1, 4, 43].

Marine Environment and Public Health 271

High concentrations of these microbes within coastal waters should indicate that the water or even seafood may be contaminated by human waste [1, 49]. However, the use of indicator microbes to test the quality coast waters for recreation and sea food consumption has been questioned, particularly in the subtropical and tropical marine environments, mainly in areas with no point source of contamination identified [1, 50]. An example is bacteria species from the families Aeromonadaceae and Vibrionaceae that are naturally inhabitants of the marine environments. Many species of this family are not related with fecal contamination of coastal waters; therefore, the use of enteric bacteria as indicators of microbiological water quality is strongly limited [1, 50]. *Vibrio* species, especially *V. cholerae, V. parahaemolyticus*, and *V. vulnificus*, are frequently associated with infectious diseases through the ingestion of shellfish or even fish [42, 50, 51]. *Vibrio* and *Aeromonas* species are clinically important for humans and biodiversity health, causing gastroenteritis of infections through the open wounds resulting in septicemia. A large number of people worldwide have been impacted by the infections of pathogenic microbes in coastal waters. More than 170 million cases of respiratory and enteric impairments associated with recreation and seafood consumption coastal waters contaminated with infectious microbes have been reported [52]. In the United States (USA) 33% of shellfish harvesting waters are impacted by micropathogens. Currently, 62% of the coastal beaches of the Rio de Janeiro state (Brazil) are classified as inappropriate for recreation, principally due to contamination with fecal bacteria. In addition, 20,300 recreational beach warnings were reported in USA in 2008 due to the fecal microbe presence

In Table 1 we present some results of bacteriological surveys (Aeromonadaceae and Vibrionacea species) that have been carried out with many specimens of marine mammals, seabirds and sea turtles from Brazilian coast. The microbiological samples were collected during a long term beach monitoring program for research and conservation of marine mammals, seabirds and sea turtles. This monitoring program has been conducted since 1999 by the GEMM-Lagos from the National School of Public Health (ENSP/FIOCRUZ). The bacteriological analyses were conducted in the *National Reference Laboratory for Bacterial Enteroinfections* (LRNEB) from the Oswaldo Cruz Institute (IOC/FIOCRUZ).The samples were collected through the sterilized swabs introduced carefully in the mouth, eyes, nostrils, genital slit, anus and open wounds of sick or recently dead animals. Twenty species of bacteria were detected in the animals sampled, five and 15 belonging to the family Aeromonadaceae and Vibrionaceae respectively. The most prevalent microbial species at the marine animals sampled were *Vibrio alginolyticus* and *Aeromonas caviae*, both representing 69% of detection. Green sea turtle (*Chelonia mydas*), Guiana dolphins (*Sotalia guianensis*) and Kelp gull (*Larus dominicanus*) presented 65, 45 and 35% of the 20 species of bacteria found in

Interestingly, the three more affected species share the same habitat preferences. Both marine species are commonly observed in coastal waters of Rio de Janeiro state and prey on coastal marine food. Kelp gull are commonly found in high density consuming rest of human food at the beach, and coastal dead fishes. It is important to highlight that humans are exposed to the feces of this bird during recreation on the beach. All green sea turtles

in coastal waters [53].

the analyses, respectively.

In Brazilian coastal water, toxic algae bloom has caused impacts on biodiversity and resulting economic impairment, principally on aquaculture and fishery activities. In Baía de Todos os Santos, Bahia state (Brazilian coast), a massive mortality of fishes and shellfishes was registered in 2007. About 50 tons of fishes and shellfishes were killed, which resulted in negative consequences for fisheries and aquaculture, due to the prohibition to commercialize organisms for consumption from this contaminated area. Similarly, in Florianópolis, Santa Catarina state, southern Brazil, an harmful algal bloom of pseudonitzschia were identified, resulting in a preventing official measure to protect the population against the effect caused by the event. Despite the identification of harmful algal blooms in coastal regions of Brazil and their association with impacts on biodiversity, few studies have focused to understand the impacts on human health. However, cases of human death have been registered associated with consumption of water from reservoirs with bloom of cyanobacteria potentially hazardous.

A drastic epidemic gastroenteritis outbreak was registered in Itaparica, region of Bahia State associated with the flooding of a Dam reservoir in 1988. From about 2,000 gastroenteritis cases identified, 88 resulted in death along a period of 42 days. Bacterial, toxicological and virological analises were conducted in fecal and blood samples from the patients, and drinking water was examined for microorganisms and metals. Clinical results were also reviewed to understand and identify the etiologic agent. The laboratory analyses indicated that the source of the epidemiology was water from the Dam, which revealed the presence of high concentrations of toxin produced by cyanobacteria (genus *Anabaena* and *Microcystis*). The cases of infectious disease were restricted to the areas supplied by drinking water from the dam. Also in 1996, 54 fatalities were recorded in Caruaru (Pernambuco state, northeastern Brazil) in hospitalized patients with chronic renal failure. During hemodialysis sessions, the patients received untreated water contaminated with cyanobacteria.
