For the last ten years new offshore oil fields were brought into production in the Santos Basin. This has led to an increase in the processing and transportation of crude oil and its derived products, hence posing new threats to the integrity of coastal environments and human resources. The Brazilian Ministry of Environment responded by coordinating an initiative aimed at mapping the sensitivity to oil spill of the Brazilian coastline. The results for the Santos Basin are presented here, for which the appropriate technologies had to be integrated in order to cover over 1300 km of the coastal environment. A partnership between public and private sectors was established in order to achieve high-quality mapping standards by sharing data and expertise. A total of ten ETM+ Landsat images have been mosaicked and processed using spectral image techniques such as restoration and band fusion. Remote sensing and field data have been organized into a digital database following an object-oriented model devised to allow the retrieval and upgrading of spatial and tabular data. These procedures are now standard practices for mapping the sensitivity to oil spill of other marine basins in Brazil. A total of 44 maps have been produced in three different geographic scales for specific contingency planning and spill scenarios. Parana state has 82% of its coastline occupied by mangrove vegetation, the most sensitive ecosystem. In contrast, 52% of the Rio de Janeiro coastline are composed of different types of rocky shores, from vertical impermeable substrates to thalus deposits. Rio de Janeiro also has the largest proportion of sandy substrates, with 41% of its coastline. Many other diagnostic information and quantitative analyses can be carried out by querying the available geographic database, which are necessary for any contingency planning and emergency response actions.

The discovery and subsequent mapping of an ancient shoreline at 25 m depth in N-E Brazil by TM-Landsat imagery is described. The study area is located on a tectonically stable part of the Brazilian shelf which presently shows a minor uplift rate of 0.2 mm year-1, to the north of Natal in the State of Rio Grande do Norte. This submerged shoreline is characterized by the occurrence of a large number of long beachrock outcrops (> 3 km in length), observed by diving, which are comparable to their analogues seen on the present-day beaches of the adjacent coast. The good state of preservation of this shoreline and the large number of carbonate rock 'reefs' on it suggest abruptness of a return to transgressive sea-level trend with high growth rates subsequent to a long-lived sea-level relating to the 11000-9000 yr B.P. band. By reviewing high resolution paleoclimatic data from this period, we conjecture that this stillstand could be a consequence of the Younger Dryas cold event in the north Atlantic, which might have also had importance as a driving morphogenetic process for coasts in a global scale.

A study of the shaping of the seafloor morphology on the brazilian northeast continental shelf caused by climatic changes in the beginning of the Holocene is being made with the support of TM-Landsat 5 data. Special emphasis is given on analysis of data from ancient shorelines between 20-45m depth, to be correlated with abrupt global climate change between 10000-8000 BP. The transport of a quartz sand deposit by the ocean currents through time, effected by active sandwave fields at the 20 m isobath is also described. Two images were used (path/row 214/64 and 215/63), corresponding to two dates: 1984 and 1989. Geometric correction, filter application and constrast enhancement were performed. A comparison between 84' and 89' images was carried out, to detect changing patterns of the sand waves, along a 5 year period, caused by the seasonal wintertime wind-forced ocean currents. Based on this registration, estimates of displacement rates for the sand deposit could be made.

A preliminary characterization of seabed morphology and mapping of algal patches within a sandstream on the northeast Brazilian continental shelf off Cape Calcanhar (where the South American coast turns sharply to the west) is presented. The study area (30 km x 30 km) is swept by unidirectional, wind-driven, tidally rectified currents, under the influence of the North Brazil Current. The study was made by use of Landsat Thematic Mapper (TM) data of the seafloor down to 40 m depth, digital bathymetric data from smooth sheets furnished by the Brazilian Navy, echo-sounder profiling and underwater surveying by SCUBA diving. A mesoscale shore-parallel natural zonation of the sandstream was observable on the TM-images: (a) an inner zone dominated by sediment resuspension caused by wave-driven turbulence and tidal currents; (b) an intermediate zone dominated by sand ribbons and other longitudinal bedforms; (c) an outer zone dominated by large-scale sand waves (underwater sand dunes) limited offshore by shore-parallel sandbanks.Image-assisted in situ work, carried out on the latter zone, gave the following results:(1) Morphology and sand composition-the asymmetric sand waves are made of medium quartz sand, with almost straight crests of lengths up to 4 km, heights between 3 and 7 m, and avalanche lee slopes of 30-degrees; on the stoss sides we recorded the presence of ripples and absence of megaripples and benthic ecosystems; on interdune areas, benthic ecosystem patches dominated by foliaceous and calcareous algae were found.(2) Sediment transport-active bedload transport was observable only during the winter season, when the strongest wind-forced currents induce flow separation at the crests and avalanche streams on the lee slope. Within the interdune areas, under the influence of the lee vortices, benthic community data confirms no appreciable abrasion due to sand transport.(3) Biology-species composition and biomass estimates from the algal patches in the first upstream trough are presented, and species composition of bryozoa observed as epibionts on live gastropod shells are analysed.This sandstream shows some similarities to one described from the southeast African continental shelf, which is also under the influence of unidirectional currents.