The estuary of the Ipojuca River with an hydrographic basin of 3,800km2 is located nearly 40km south of the city of Recife, Pernambuco State, within an area designated for the Industrial Complex (08º15'00"S - 08º30'00"S; 34º55'00"W - 35°05'00"W). The estuary extension is of approximately 15km, with a minimum depth of 0.80m at low tide and maximum of 4.00m at high tide. Salinity ranges between 0.05 and 36.00. The estuary receives a high load of sewage and wastes from 71 industries, mainly sugar cane processing factories and alcohol distilleries. The climate is warm, humid and pseudo-tropical (Köppen As'). Annual rainfall varies between 1,850 and 2,364mm, the dry season being from September to February and the rainy season from March to August. The average annual temperature and humidity is 24ºC and higher than 80%, respectively. Winds are generally from the southeast.
The sand fill for the port implantation blocked the communication of the Ipojuca River with Suape Bay, damming the waters and causing floods in the backyard agricultural areas and degradation of mangroves. As a solution, in 1983 a partial opening (250m extension and depth of 80cm) in the reefline allows the water passage. Changes in the tidal cycles occurred with 4 hours of high tide and 8 hours of low tide. Sediment deposited in the Port area increased water turbidity, impacting directly on the primary productivity of the area. Water transparency was reduced during the rainy season with a minimum of 0.05m and maximum of 2.00m at dry season (Neumann-Leitão, 1994; Neumann et al., 1998).
The chemistry of the waters changed after the construction of the Port. Salinity was polihaline to limnetic (Cavalcanti et al., 1980) and changed to mesohaline/limnetic, except at the station closest to the reef where salinity remained 36. Concentrations of dissolved oxygen remained within normal average (4,0 ml/l-1). However, in the dry season (October to March and at low tide), polluted and semi-polluted zones continued to be detected in the internal areas of the estuary. The concentrations of nutrient salts varied along the whole year and increased gradually from the river mouth to internal area, being higher in the rainy season and at low tide (nitrate-N ranged from 0.003 mmol.l-1 to 46.170mmol.l-1; phosphate-P from 0.071m mol.l-1 to 6.732mmol.l-1 and silicate-Si from 9.305m mol.l-1 to 276.251mmol.l-1