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The health of the bay

Project maps sources of pollutants and marine currents in Todos os Santos Bay

Luciano AndradeView of Salvador: late afternoon on Todos os Santos BayLuciano Andrade

From Salvador

It was around 11:00 on Tuesday morning of October 16 when the boat piloted by Jailson Bittencourt de Andrade, a chemist, stopped at a sandbar on the channel connecting Aratu Bay to the vast emerald waters of Todos os Santos Bay. In the strip of sand exposed by low tide about 40 women and a few children, all black, moved about as they squatted and looked through the sand. They were gathering shellfish. With a spoon or with just their fingers, they dug up small shellfish known as chumbinho or papa-fumo which are slightly larger than a thumbnail. It takes hours of work, often under an intense sun, to fill a large basket with the shellfish, which, once cleaned, weigh two pounds and sell at R$17 to fish traders in the region. Since their commercial value is low, the chumbinho and other shellfish, such as mollusks with or without shells, are the main source of animal protein for the nearly 15,000 families of fishermen and shellfish gatherers of Todos os Santos Bay. Living below the poverty line, many of these families today eat some of the same foods as did the early humans who thousands of years ago occupied the coast of what would become Brazil.

Now, however, the recommendation is to consume fish and seafood caught in Aratu, Itapagi, Suba and other industrialized areas of Todos os Santos Bay in moderation. They are contaminated. Concentrations of some metals are at levels higher than those accepted by health authorities such as the National Health Monitoring Agency. Many of these metals are chemical elements which, at very low concentrations, are essential for good health but, at high levels, may be toxic. Eating fish and shellfish from contaminated areas a few times a week is not enough to cause a health risk, say researchers at the Federal University of Bahia (UFBA) which, under the coordination of Andrade, have in recent years been mapping environmental pollution in Todos os Santos Bay. But fishermen and shellfish gatherers, who consume seafood almost every day, are more vulnerable to developing health problems associated with continued exposure to high concentrations of some of these metals.

“Children are the most at risk,” says Vanessa Hatje, coordinator of UFBA’s Laboratory of Chemical Oceanography, who came along on the visit to the points of Todos os Santos Bay where measurements were taken. “Actually the body’s capacity to dilute chemical elements is directly related to body mass,” explained Hatje, who is Andrade’s right hand in phase one of the Todos os Santos Bay Project. Planned to continue until 2038, this project, which involves nearly 50 researchers, is investigating the physical, biological, cultural and historical characteristics of the region and thus is contributing to the sustainable management of this bay, the second largest in the country and second only to São Marcos in Maranhão.

Between 2006 and 2010, Hatje and Manuel Nogueira de Souza, an oceanographer, and Claudia Windmöller, of the Federal University of Minas Gerais, collected shellfish from 34 points along Todos os Santos Bay. Chemical analysis showed that at least four elements (arsenic, zinc, selenium and copper) appear in relatively high concentrations in shellfish and oysters. The most contaminated shellfish, according to an article published in 2011 in the journal Marine Pollution Bulletin, had been caught in Aratu, near the area where the shellfish gatherers worked on that October morning, and in the Subae River estuary, northwest of there.

This was expected to be so. Aratu Bay, located about 20 kilometers north of Salvador, is home to one of the three busiest ports in Todos os Santos Bay. Aratu is surrounded by chemical, petrochemical, metallurgical and food industries, among others. Less than 50 kilometers to the northeast lies the Camaçari petrochemical complex, the largest in South America. While in the Subae River estuary, the main source of contaminants in the extreme northwest of Todos os Santos Bay was for a long time the mining company Plumbum. It was shut down in 1993 but for nearly three decades it released large quantities of lead, cadmium, arsenic and zinc into the Subae.

“There were few studies, almost all with restricted circulation, on the environmental contamination in the bay,” says Andrade, who also coordinates the National Institute of Science and Technology for Energy and Environment. “These surveys were based on spot measurements, which used different techniques; now we are establishing protocols that will enable us to monitor the evolution over time,” adds Andrade, who years ago conducted an assessment of air quality on Todos os Santos Bay, known as Kirimurê by the Tupinambá who inhabited the region before the arrival of Europeans.

His group set up pollutant measuring stations at three points: at the Lapa bus station, a busy bus terminal in the center of Salvador; at the port of Aratu, which has intensive activity in cargo and ore transport; and in Bananeira, a fishing village with about one thousand inhabitants on Ilha de Maré. The result was to some extent surprising. The air in the bus terminal was more polluted than some had imagined. But they did not expect the air in Bananeira to be almost as bad as that of the port of Aratu, five kilometers away. “During certain hours of the day, it was as if the Bananeira residents were inside the port,” Andrade said, pointing to a cluster of houses between banana plantations, as he steered the boat through the channel that separates Ilha de Maré from the port.

In addition to systematic and long-term measurement of contaminant levels, the researchers are trying to understand the movement dynamics and destination of the contaminants in the bay and their impact on living organisms. With Francisco Barros, of UFBA’s Benthic Ecology Laboratory, Hatje assessed the concentration of metals in the water, sediments and fauna of the three major rivers that flow into the bay — the Jaguaripe, the Paraguaçu and Subae. They found that Plumbum, even though it has been out of operation for three decades, still pollutes the Subae and surrounding areas. In winter, rain washes the deposits and piles of slag of the former mining company and conveys more contaminants to the river, which is less than 500 meters away. In general, the metals dissolved in the water adhere to particles in suspension and progressively accumulate in the sediments on the river bottom as it moves toward the mouth. At some points, the concentration reaches levels that are toxic to benthic fauna.

044-049_Baia_201“At one of the stations in the Subae River estuary we did not find any creatures living in the sediment,” says Barros, who now conducts tests to determine if the disappearance of the benthos is a consequence of the toxicity of the substrate or natural stress on that section of the river. Barros recently discovered that tropical estuaries operate differently from those of temperate environments. In Todos os Santos Bay the diversity of benthic species — shellfish, polychaetes and some fish —continue to increase as the salinity of the water rises, while in estuaries in Europe and the United States the variety of species tends to fluctuate: it is greater in stretches of low and high salinity and low in intermediate salinity.

Since the water flowing into the bay from rivers is small compared to its total volume, the interchange of water between the bay and the ocean, by way of the tide, largely determines the capacity of contaminants to be dispersed and diluted and the amount of suspended particulate matter. In an attempt to understand in detail the movement and flow of water and materials into and out of the bay, William Lessa, a geographer and expert in sedimentology, began monitoring the currents in motion within Todos os Santos Bay. Once a month he travels to 10 stations and measures the physical-chemical characteristics (salinity, temperature and particulate matter) and collects plankton. In three of the seasons, simpler equipment, the size of a flashlight, continuously records information about suspended material and the salinity and temperature of the water. Thus, it is anticipated that the direction and speed of currents moving the particles inside the bay at different times of the year will be categorized. “We want to see if Todos os Santos Bay is importing or exporting water and particulate matter to the ocean,” he explains.

Using current data collected in 2003, Lessa measured the movement of water between the bays of Aratu and Todos os Santos. A preliminary analysis indicates that, in winter, deeper currents carry water from the upper to the lower bay. Then surface currents carry waters originating in Aratu into Todos os Santos Bay. According to Lessa, there are indications that in the summer the flow is reversed.

Still it is impossible to know if what he saw in that area also applies to the interaction between Todos os Santos Bay and the Atlantic Ocean. By the end of the year Lessa will install equipment that measures the flow of water (current meters) at two points along the bay, which will complement the information that is being collected. He estimates that he will need to collect data over a period of 15 years to map the cycles of the waters flowing between the bay and the ocean. Indeed the climate that is responsible for changing the speed and direction of winds, rainfall and salinity of the coastal region fluctuates in the South Atlantic in cycles of 3 years, 10-14 years and 30 years duration.

Zelinda Leão and Ruy Kikuchi, UFBA geologists monitoring the health of corals along the Brazilian coast, expect data on ocean currents in the bay will help clarify what is happening with the coral. There are two big coral reefs in Todos os Santos Bay: one in the inner region near Ilha dos Frades and another in the open sea opposite Itaparica Island. In recent years, Leão and Kikuchi have seen several episodes of coral bleaching.

Corals lose their natural color and become whitish when microscopic algae that live within them, the zooxanthellae, die or are eliminated – these algae provide oxygen and nutrients that help corals to produce a calcareous skeleton. Although not always fatal to the coral, bleaching is an indication that something is not right. Kikuchi suspects that the problem in Todos os Santos Bay is due to the rising global temperature of seawater, episodes of increased particulate matter, which muddy the water and reduce the penetration of light, and possibly chemical pollution. In 2011 the researchers observed bleaching at several points near the port of Salvador, which was being dredged. Furthermore, almost a decade ago they discovered that one of the eight species native to the Brazilian coast and living there, the Mussismilia braziliensis, had disappeared. More recently, teams from UFBA, Rio de Janeiro State University (UERJ), the Federal University of Alagoas (UFAL) and the Pró-Mar NGO reported the spread of sun coral, an invasive species adapted to turbid environments.

The waters and the environment surrounding this bay have always paid a high price for the bay having served as the port-of-entry to Brazil. Since the expedition of the Portuguese explorer Gaspar de Lemos anchored there on November 1, 1501, All Saints Day in the Catholic tradition, there have been successive changes. The founding of Salvador in 1549 by Thomas de Souza, who was sent by the king of Portugal to create a fortress city and begin to occupy the lands of the New World, provided the labor and axes that turned the lush Atlantic Forest into fuel and lumber, opening space for sugarcane and sugar mills, the most advanced agribusiness unit of colonial Brazil. The most significant change, however, would occur later with the discovery of oil in the Recôncavo Baiano and installation of the Landulpho Alves refinery in 1950, in the town of Mataripe, which would lead the government of Bahia to invest in petrochemicals as an economic development model.

Industrial development of the region has recently resumed, with investment in a new metallurgy-mechanical complex, the expansion of ports and construction of shipyards. “Lately measures to control and reduce the emission of metals have been adopted, but there has been little progress,” Hatje explained on the return trip through the bay. “At various points raw untreated sewage still reaches the rivers and the bay.” Despite these problems, Todos os Santos Bay still retains well preserved areas, such as the mouth of the Jaguaripe River, south of Itaparica Island. Its health, in general, is considered much better than that of Guanabara Bay, in Rio de Janeiro, which occupies an area three times smaller and is surrounded by a population three times larger. But Hatje fears that this will not continue to be so for much longer. Before the boat docked at the marina, she lamented: “I believe the environmental conditions will get even worse before they get better.”

Exhibition on the beach: photographs of everyday fishing on display for the riverside community

Exhibition on the beach: photographs of everyday fishing on display for the riverside community

Cultural and historical record

While some of the researchers are dedicated to learning the physical and biological aspects of Todos os Santos Bay, Gal Meirelles and CaioAdan, respectively an ethnographer and historian, both from Feira de Santana State University, are recording the cultural characteristics that are beginning to be lost and historical information unknown to the public.

For nearly five years, Meirelles lived in the Baiacu community on Itaparica Island, and recorded its way of life and the different techniques used by artisanal fishermen of Todos os Santos Bay, knowledge that does not seem to interest the younger generation. “Communities lack jobs for young people and so they admire life in Salvador, but going to the capital only gets them temporary jobs and underemployment,” says Meirelles. This ethnography of fishing led to a video: Fishing masters; and a series of photographs: Our daily fish, exhibited in the community of fishermen. With Milton Moura, a UFBA sociologist, Meirelles worked on the photographic record and a video of traditional festivals on Itaparica Island celebrating the independence of Brazil.

She also assisted Caio Adan in researching the archives and museums of Brazil and Europe. In visits to collections in Bahia, Rio de Janeiro, Portugal and Spain, he had access to about 200 maps made between the sixteenth and twentieth centuries and began to document the cartographic heritage of Todos os Santos Bay.

This material is valuable, such as a mid-seventeenth century map showing how nets were used to trawl for the xaréu, a large fish whose capture required the participation of dozens of men. Or a letter found in the Itamaraty Archives in Rio, indicating the existence of an unknown channel of the Itapagipe Peninsula. This channel (it is not known if it was actually built) would have facilitated navigation between the north region and the center of Salvador.

Adan noted that beginning in the nineteenth century, the letters become more technical and precise. “Possibly to aid navigation in the bay,” he says. He plans to describe the collected material and set up a database on the Internet and make it available to other researchers.

According to Adan, an initial assessment of the maps corroborates the idea that Todos os Santos Bay played a central role in the formation of the state of Bahia. For a long time, it has been understood as a more expansive space than the one outlined by a geographical accident of the same name.

Scientific articles
BARROS, F. et al. Subtidal benthic macroinfaunal assemblages in tropical estuaries: Generality amongst highly variable gradients. Marine Pollution Bulletin, October 2012.
HATJE, V.; BARROS, F. Overview of the 20th century impact of trace metal contamination in the estuaries of Todos os Santos Bay: Past, present and future scenarios. Marine Pollution Bulletin, July 2012.
SOUZA, M. M. et al. Shellfish from Todos os Santos Bay, Bahia, Brazil: treat or threat? Marine Pollution Bulletin, October 2011.