Analysis of mangrove forest succession, using sediment cores: A case study in the cananéia -iguape coastal system, São Paulo-Brazil

Sediment cores are an essential tool for the analysis of the dynamics of mangrove succession. Coring was used to correlate changes in depositional environments and lateral sedimentary facies with discrete stages of forest succession at the Cananeia-Iguape Coastal System in southeastern Brazil. A local level successional pattern was examined based on four core series T1) a sediment bank; T2) a smooth cordgrass Spartina alterniflora bank; T3) an active mangrove progradation fringe dominated by Laguncularia racemosa, and; T4) a mature mangrove forest dominated by Avicennia schaueriana. Cores were macroscopically described in terms of color, texture, sedimentary structure and organic components. The base of all cores exhibited a similar pattern suggesting common vertical progressive changes in depositional conditions and subsequent successional colonization pattern throughout the forest. The progradation zone is an exposed bank, colonized by S. alterniflora. L. racemosa, replaces S. alterniflora as progradation takes place. As the substrate consolidates A. schaueriana replaces L. racemosa and attains the greatest structural development in the mature forest. Cores collected within the A. schaueriana dominated stand contained S. alterniflora fragments near the base, confirming that a smooth cordgrass habitat characterized the establishment and early seral stages. Cores provide a reliable approach to describe local-level successional sequences in dynamic settings subject to drivers operating on multiple temporal and spatial scales where spatial heterogeneity can lead to multiple equilibria and where similar successional end-points may be reached through convergent paths

A combined approach of benthic mapping of Caraguatatuba Bay, Brazil, with recommendations for management practices

Benthic habitat mapping is an important first step towards ecosystem-based management. In a top-down approach, benthic mapping of a semi-enclosed bay in south-eastern Brazil was performed using a combined approach of acoustic RoxAnn survey and benthic samples. An inventory of the benthic macrofauna as well as unsupervised classifications of the acoustic data provided information about sediment patterns and potential areas of ecological importance, and a new zoning scheme is suggested based on the macrofauna analysis. The RoxAnn survey proved suitable to determine sediment characteristics, however, species–environment relationships cannot be revealed by acoustic techniques only. Based on the data presented here, acoustic surveys could become an important tool in future monitoring programmes following the bottom-up approach of seabed classification protocols for an ecosystem-based management to improve existing coastal ecosystem management strategies in Brazil. A combined approach of benthic mapping of Caraguatatuba Bay, Brazil, with recommendations for management practices (PDF Download Available). Available from: https://www.researchgate.net/publication/257423766_A_combined_approach_of_benthic_mapping_of_Caraguatatuba_Bay_Brazil_with_recommendations_for_management_practices [accessed Jun 6, 2017]

Deep pockmarks as natural sediment traps: a case study from southern Santos Basin (SW Atlantic upper slope)

This study examines the role of deep pockmarks in acting as natural sediment traps. Multibeam bathymetry, single-channel seismic and sediment samples data were used for describing the morphology of pockmarks as well as the nature of sediments inside and outside these depressed features, in an area of Santos Basin (SW Atlantic upper slope), dominated by the strong flow of Brazil Current. Results show that the grain size and chemical composition of sediments inside pockmarks are distinct from the outside. Also, radiocarbon dating shows that Holocene ages are found only in samples located inside the pockmarks. Combination of sedimentological, geochemical and geochronological data allowed to recognise that deep pockmarks might present distinct sediment deposition processes when compared with those of shallow pockmarks, in which turbulence impedes sediment deposition, as reported in the literature.The authors acknowledge the crew and researchers of the two surveys held in 2016 and 2017, onboard R.V. Alpha Crucis. The São Paulo Science Foundation (FAPESP, grants 2014/08266-2, 2016/22194-7 and 2015/17763-2) funded this work. Partnerships between MM.de M., U.S. and F.L-S., are funded by FAPESP (grant 2017/50191-8) and the Brazilian National Research Council (CNPq, grant 401041/2014-0), respectively. M.M.de M. acknowledges CNPq for the research grants 303132/2014-0 and 300962/2018-5. This study was financedin partby the Coordenação deAperfeiçoamento dePessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 (R.B.R. MSc. Scholarship)

The Alpha Crucis Carbonate Ridge (ACCR): Discovery of a giant ring-shaped carbonate complex on the SW Atlantic margin

Recently acquired bathymetric and high-resolution seismic data from the upper slope of Santos Basin, southern Brazilian margin, reveal a major geomorphological feature in the SW Atlantic that is interpreted as a carbonate ridge - the Alpha Crucis Carbonate Ridge (ACCR). The ACCR is the first megastructure of this type described on the SW Atlantic margin. The ~17 × 11-km-wide ring-shaped ACCR features tens of >100-m-high steep-sided carbonate mounds protruding from the surrounding seabed and flanked by elongated depressions. Comet-like marks downstream of the mound structures indicate that the area is presently influenced by the northward flow of the Intermediate Western Boundary Current (IWBC), a branch of the Subtropical Gyre that transports Antarctic Intermediate Water. Abundant carbonate sands and gravels cover the mounds and are overlain by a biologically significant community of living and dead ramified corals and associated invertebrates. The IWBC acts as a hydrodynamic factor that is responsible for both shaping the bottom and transporting coral larvae. We contend that the ACCR was formed by upward fluid flow along active sub-surface faults and fractures that formed by lateral extension generated by the ascending movement of salt diapirs at depth. The ACCR provides an important modern and accessible analogue for a seabed carbonate build-up related to sub-surface hydrocarbon systems.The authors are indebted to the crew and researchers who participated in the Jan-Feb 2019 survey aboard the R.V. Alpha Crucis for their constant support. Acknowledgements are also due to the São Paulo Science Foundation (FAPESP grants 2014/08266-2, 2015/17763-2, and 2016/22194-0). MMdeM acknowledges the Brazilian National Research Council (CNPq, grant 300962/2018-5). The partnership between MMdeM and the US was supported by FAPESP (grant 2017/50191-8 – SPRINT Program). The partnership between MMdeM and F.J.L. was supported by CNPq (grant 401041/2014-0). The authors gratefully acknowledge support from Shell Brasil through the BIOIL project at the Oceanographic Institute of the University of São Paulo and the strategic importance of the support given by ANP through R&D levy regulation. We thank Petrel-Schlumberger for providing academic licenses that enabled the seismic interpretation

Analysis of mangrove forest succession, using sediment cores: A case study in the cananéia -iguape coastal system, São Paulo-Brazil

Sediment cores are an essential tool for the analysis of the dynamics of mangrove succession. Coring was used to correlate changes in depositional environments and lateral sedimentary facies with discrete stages of forest succession at the Cananéia-Iguape Coastal System in southeastern Brazil. A local level successional pattern was examined based on four core series T1) a sediment bank; T2) a smooth cordgrass Spartina alterniflora bank; T3) an active mangrove progradation fringe dominated by Laguncularia racemosa, and; T4) a mature mangrove forest dominated by Avicennia schaueriana. Cores were macroscopically described in terms of color, texture, sedimentary structure and organic components. The base of all cores exhibited a similar pattern suggesting common vertical progressive changes in depositional conditions and subsequent successional colonization pattern throughout the forest. The progradation zone is an exposed bank, colonized by S. alterniflora. L. racemosa, replaces S. alterniflora as progradation takes place. As the substrate consolidates A. schaueriana replaces L. racemosa and attains the greatest structural development in the mature forest. Cores collected within the A. schaueriana dominated stand contained S. alterniflora fragments near the base, confirming that a smooth cordgrass habitat characterized the establishment and early seral stages. Cores provide a reliable approach to describe local-level successional sequences in dynamic settings subject to drivers operating on multiple temporal and spatial scales where spatial heterogeneity can lead to multiple equilibria and where similar successional end-points may be reached through convergent paths.SCOPUS: ar.jinfo:eu-repo/semantics/publishe