This section provides a summary of what is known about the chemical and biological oceanography of the Mozambique coastal and marine waters. The available information on these subjects was collected during the Portuguese and French research conducted in the 1960s. Further research were undertaken on-board the research vessel, Dr. Fridtjof Nansen in 1970s, 2007 and 2008. 






Nutrients 

The general circulation in the Mozambique Channel is apparently highly influenced by the ocean bathymetry. Dynamic processes associated with eddies such as eddy induced upwelling or eddy interaction, drive transport and distribution of nutrients which support the whole marine food chain. It has been documented that eddies can shape the distribution of both phytoplankton, zooplankton and fish larvae (Lutjhearms 2006).  Eddies flowing along the coast may cause the advection of coastal rich waters at their edges and move nutrients into the channel. 


The Sofala Bank located between the latitudes 16º S - 21ºS, is influenced by the discharges from Zambezi, Pungué, Buzí and Save rivers. It is one of the most productive shelf regions of Mozambique (Lutjeharms 2006, Barlow 2007, 2008). The results from the R/V Dr. Fridjof Nansen cruise in 2007, showed a clear variability of nutrient concentration, with the highest concentrations occurring in the Angoche shelf area in the north, Sofala Bank in the central region and Delagoa Bight in the southern shelf region. 


The issues related to biogeochemical cycles are related to the primary production, and since the primary producers sustain all the organisms in the food web, issues consequently relate to biodiversity maintenance, health and productivity of the ecosystems and habitats. Gaps The biological and oceanographic characteristics of the Mozambique Channel and adjacent shelf regions are poorly known due to the lack of research in these regions.

Further work should be conducted to determine the role of eddies in the biophysical functioning of the Mozambique Channel. There is a gap in knowledge of the influence of nutrient inputs through rivers and rainfall. The contribution of mangroves in the primary production of the coastal waters is poorly understood. There is an overall lack of data on nutrient variability in Mozambique. In-situ nutrient measurements in the open sea are expensive. Persistent organic pollutants

The Mozambique Channel is an important route for large oil tankers. Since there is no control on tank cleaning in the deep sea, the risk for contamination of waters by POPs is high. In 1992 more than 16,000 tonnes of heavy fuel-oil were spilled by the Katina P tanker off the Mozambique coast threatening the coastal and marine ecosystems. Eddies travelling from the north to the south may concentrate pollution in localized areas within the Mozambique Channel in the case of oil spills. However, it is known that main sources of pollution are landbased, particularly those associated with domestic waste from coastal cities and from activities such as agriculture, industries, mining and commercial operations in ports and harbours. Most Mozambican coastal cities have obsolete systems for sewage treatment. Thus many pollutants enter marine waters untreated.


Sewage and domestic solid wastes

Faecal coliform content in the water within the Mozambique channel adjacent to the Infulene River in Maputo is high (4.6x105 bacteria counts/100 ml). aecal coliform, faecal streptococci and E. coli  have also been detected in both marine waters and in shellfish tissues in Maputo Bay. The concentrations found in shellfish is extremely high. Some places in Maputo Bay, particularly where the discharge of sewage takes place, such as Miramar at the entrance of the Maputo Estuary, are not safe for swimming. High levels of microbial pollution have also been found at Beira and Nacala Bays, although the concentrations are low compared to those observed in Maputo Bay (Motta et al. 1998).

aecal coliform, faecal streptococci and E. coli  have also been detected in both marine waters and in shellfish tissues in Maputo Bay. The concentrations found in shellfish is extremely high. Some places in Maputo Bay, particularly where the discharge of sewage takes place, such as Miramar at the entrance of the Maputo Estuary, are not safe for swimming. High levels of microbial pollution have also been found at Beira and Nacala Bays, although the concentrations are low compared to those observed in Maputo Bay .

Untreated industrial waste Most of the industries in Mozambique are located in coastal cities such as Maputo, Matola and Beira. Most of the industries do not have adequate industrial effluent treatment facilities. Thus industrial effluents are discharged directly into tidal channels or in coastal waters causing pollution. Analysis by the National Laboratory for Food and Water and Maputo Water Authority have revealed the presence of heavy metals particularly lead in different locations within the Port of Maputo, in the mouths of Matola and Maputo rivers and in Nacala Bay.

Agricultural run-off Agricultural activities within the coastal region and in the hinterland areas also contribute to the pollution of coastal, marine and freshwater environment, through sediments, pesticides and fertilizer residues. Since most of the agricultural activities takes place along or close to main river channels, rivers are the main pathways through which agrochemicals enter the coastal and marine environment. 

The major rivers with intensive agricultural activity are Monapo (in Nampula Province), Zambezi,  Pungoé, Limpopo and Incomati. The hinterlands of these rivers are important agricultural areas extending to neighbouring countries (Massinga and Hatton 1997). The contribution of Mozambican farming to the pollution of waters of these rivers is however negligible.