WIOMSA ScienceNews – WIOBENTH: Mapping project makes steady progress

The effort to identify numerous communities of plants and animals that occupy the sea floor of the WIO region remains minimal. Nonetheless, there is growing interest amongst researchers in Western India Ocean region to identify and characterize benthic ecosystems. Since 2019, a dedicated team of marine researchers has been studying WIO seabed habitats through the MASMA funded WIO-Benth project. This week’s issue of WIOMSA ScienceNews features the work that Sean Fennessy and others are doing in studying some of the unique characteristics about the Western Indian Ocean Seabed that have never interrogated before.

WIO-BENTH: Mapping project makes steady progress

By Sean Fennessy

The WIO-Benth – Identification, characterization and vulnerability assessment of benthic ecosystems in the western Indian Ocean (WIO) – has been making steady progress since it started in late 2019, the challenges of COVID-19 notwithstanding. It is ambitiously aiming at mapping the WIO shelf and upper slope seabed habitats, and characterizing the benthic faunal communities of these vast, largely unknown areas.

The project is a collaboration with scientists from the Kenyan Marine and Fisheries Research Institute, Tanzania Fisheries Research Institute, Centre d’Etudes et du Développement des Pêches (Madagascar), Instituto Nacional de Investigação Pesqueira (Mozambique), the Institute for Marine Research (Norway), the South African Institute for Aquatic Biodiversity, and the Oceanographic Research Institute (South Africa). The EAF-Nansen Programme has also been a valuable contributor to the project, notably via the use of extensive survey data from the Norwegian research vessel Dr Fridtjof Nansen, which has operated in the WIO region for many years. Supplemented by data from other surveys, the objective is to collate and validate the data, and analyse them in a series of workshops – the hosting of which has been stymied by the global pandemic – and to ultimately produce biotope maps for use in marine spatial planning. The outputs will assist WIO countries in meeting their Sustainable Development Goals and will in due course be housed with the Nairobi Convention Clearing House.

Some of the data sets have never been interrogated, and scientists from all the collaborating institutes are involved in this challenging task. Data sets include acoustic seabed soundings, physico-chemical attributes of the water, sediment characteristics, and demersal faunal community composition. Apart from the EAF-Nansen Programme, collaboration with other past and present projects and programmes that have mutual interests and commonalities, such as activities of the second phase of the Indian Ocean Expedition (IIOE 2), are developing.

Processing of the demersal fauna data is more advanced, thanks to earlier analyses undertaken in a review of the EAF-Nansen Programme’s activities in the WIO in 2017  (http://www.fao.org/3/i7652e/i7652e.pdf). While inclusion of other trawl data sets is still pending, an attempt is being made to assign characteristics to the seabed based on faunal occurrence.  Having now produced a reasonably comprehensive list of accepted, standardized names of trawled benthic taxa from the WIO, preferred seabed habitats for these taxa have been assigned from the literature, and designated to basic categories: soft bottom, hard bottom, and mixed. Based on the relative proportions per trawl catch of benthic taxa with a preference for each of these, preliminary faunal-derived maps of inferred seabed type have been produced for areas where adequate trawl sampling has taken place (Figure 1). These maps will be expanded as additional data become available, and will be used to corroborate seabed typologies produced by more conventional means, such as acoustic soundings, sediment grabs, etc.

Processing of these other data types and sets is progressing – some are more difficult to deal with than others, depending on how they were generated. Only one face to face meeting of the project leads has been possible so far (in March 2020, just before the pandemic struck the region), but as countries have increasingly managed to come to terms with managing infection risks, data analysis workshops will start to take place more frequently, with increasing production of project outputs.

For more information on WIO-Benth, please contact:  Se***@or*.za


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