Bettina Martin

University of Hamburg | UHH · Institut für Hydrobiologie und Fischereiwissenschaft

Diazotrophic cyanobacteria such as Trichodesmium play a crucial role in the nitrogen budget of the oceans due to their capability to bind atmospheric nitrogen. Little is known about their interoceanic transport pathways and their distribution in upwelling regions. Trichodesmium has been detected using a Video Plankton Recorder (VPR) mounted on a re...

Quantifying greenhouse gas (GHG) emissions is essential for mitigating global warming, and has become the task of individual countries assigned to the Paris agreement in the form of National Greenhouse Gas Inventory Reports (NIR). The NIR informs on GHG emissions and removals over national territory encompassing the 200-mile Exclusive Economic Zone...

Under the umbrella of SPACES (Science Partnerships for the Adaptation to Complex Earth System Processes in Southern Africa), several marine projects have been conducted to study the coastal upwelling area off southwestern Africa, the Benguela Upwelling System (BUS). The BUS is economically important for the bordering countries due to its large fish...

The southern African subcontinent and its surrounding oceans accommodate globally unique ecoregions, characterized by exceptional biodiversity and endemism. This diversity is shaped by extended and steep physical gradients or environmental discontinuities found in both ocean and terrestrial biomes. The region’s biodiversity has historically been th...

Diazotrophic cyanobacteria such as Trichodesmium play a crucial role in the nitrogen budget of the oceans due to their capability to bind atmospheric nitrogen. Little is known about their interoceanic transport pathways and their distribution in upwelling regions. Trichodesmium has been detected using a Video Plankton Recorder (VPR) mounted on a re...

Marine phytoplankton in the northern Benguela upwelling system (nBUS) serve as a food and energy source fuelling marine food webs at higher trophic levels and thereby support a lucrative fisheries industry that sustain local economies in Namibia. Microscopic and chemotaxonomic analyses are among the most commonly used techniques for routine phytopl...

Marine phytoplankton in the northern Benguela upwelling system (nBUS) serve as a food and energy source fuelling marine food webs at higher trophic levels and thereby support a lucrative fisheries industry that sustain local economies in Namibia. Microscopic and chemotaxonomic analyses are among the most commonly used techniques for routine phytopl...

The TRAFFIC project (Trophic Transfer efficiency in the Benguela Current) is investigating processes that drive the trophic systems of the northern and southern Benguela Upwelling Systems (nBUS and sBUS) and associated feedbacks to fisheries and climate. Small-sized Picophytoplankton (0.2–2 μm size) can account for more than 50 % of total biomass a...

The Benguela Upwelling System in the southeast Atlantic Ocean is of crucial socio-economic importance due to its high productivity. However, predicting its response to global change and understanding past changes are still great challenges. Here, we compile data obtained from a research cruise and an oceanographic mooring to demonstrate that a topo...

The Humboldt Upwelling System (HUS) supports high levels of primary production and has one of the largest fisheries (anchoveta) worldwide. The upwelling dynamics and productivity of this system are closely connected to climate variability and are hypothesized to undergo crucial climate-driven changes in the future with unknown consequences to produ...

The TRAFFIC project (Trophic Transfer efficiency in the Benguela Current) is investigating processes that drive the trophic systems of the northern and southern Benguela Upwelling Systems (nBUS and sBUS) and associated feedbacks to fisheries and climate. Despite similar upwelling volumes and similar primary production rates, the sBUS is currently f...

The northern Benguela Upwelling System (nBUS) has been facing increasing temperatures and decreasing dissolved oxygen (DO) levels over the last decades. This has implications for key processes and trophic interactions within the ecosystem including shifts in community composition, distribution ranges, and trophic levels, changes in energy flows and...

Senghor Seamount is an important fishing ground around the Cape Verde archipelago in the Eastern Central Atlantic. On an experimental field survey in October 2009 and December 2011, a total of 115 deep-sea fishes of 26 species belonging to 18 families were caught on the seamount summit, along the slopes and on the adjacent abyssal plane, using long...

Thaliacea (Tunicata) are fragile pelagic organisms, switching between sexual and asexual reproduction during their life cycle, occasionally occurring in massive blooms. During these blooms they graze large amounts of phytoplankton and microzooplankton, subsequently providing an enhanced carbon flux into deeper layers by sinking of faeces and dead a...

Seamounts are amongst the most common physiographic open ocean systems, but remoteness and geographic complexity have limited the number of integrated and multidisciplinary surveys in the past. As a consequence, important aspects of seamount ecology and dynamics remain poorly studied. We present a multi-parameter data set from individual and repeat...

Cruise MSM49 focused on the impact of the oxygen minimum zone (OMZ) and of a shallow topographic feature, Senghor Seamount, on the abundance, distribution, diversity and trophic structure of the medium-sized pelagic fauna (macrozooplankton, micronekton, and squids). Using a combination of optical and multiple net systems, the ecological zonation of...

Deepwater fish communities were sampled during exploratory surveys on two seamounts of the north- and central eastern part of the Atlantic Ocean. Demersal fishes from Ampère Seamount, located between Madeira and the Portuguese mainland, were sampled during the P384 cruise of R.V. Poseidon in May 2009 and the M83/2 cruise of R.V. Meteor in November/...

Cruise M103 NAMUFIL (Namibian Upwelling Filament Study) onboard RV METEOR was dedicated to the GENUS (Geochemistry and Ecology of the Namibian Upwelling System) project (Phase II) and represented the sixth field campaign within this program since 2008. The scientific work focused on the Namibia Benguela region between the Orange River (28.6°S) in t...

Decapods were sampled with a 1 m**2 MOCNESS (mainly upper 1000 m) in the northern Benguela Current during three cruises in December 2009, September/October 2010 and February 2011. Although pelagic decapods are abundant members of the micronekton community, information about their ecophysiology is very limited. Species-specific regional distribution...

Spatial and temporal distribution patterns of zooplankton are highly variable in the Northern Benguela Upwelling System. We studied the distribution of zooplankton (size class ≥ 0.33 mm) and used field data from four cruises that took place between March 2008 and February 2011, as well as simulation results of a regional ecosystem model. Remotely s...

Many Thecosomata (Gastropoda) produce an aragonite shell and are potentially threatened by the increasing ocean acidification. Information about these species is very important for future monitoring of the fate of this group. This paper investigates the distribution, species composition and trophic role of Thecosomata along a transect from the coas...

Decapods were sampled with a 1 m2 MOCNESS (mainly upper 1000 m) in the northern Benguela Current during three cruises in December 2009, September/October 2010 and February 2011. Although pelagic decapods are abundant members of the micronekton community, information about their ecophysiology is very limited. Species-specific regional distribution l...

Cruise MSM 17/3 onboard MARIA S. MERIAN was dedicated to the GENUS (Geochemistry and Ecology of the Namibian Upwelling System) project and represented the third field campaign within this program since 2009. The scientific work focussed on the northern Benguela region between Lüderitz (26.6°S) and Kunene (17.25°S) under low to moderate upwelling co...

Cruise M79/3 aimed at physical, biogeochemical and biological sampling at and around seamounts in the Cape Verde region. These seamounts are important targets for the local fishery, but nearly nothing is known about their ecology. In order to gain an advanced understanding of the func- tioning of these ecosystems within their special hydrographic a...

Zooplankton metabolic rates, determined from electron transfer system (ETS) activity, were studied at two seamounts (Seine: 34°N, 14°W, summit depth ∼170 m; Sedlo: 40°N, 27°W, summit depth ∼750 m) in the northeast (NE) Atlantic during three cruises in November 2003, April 2004 and July 2004. ETS activity and respiratory carbon demand were measured...

Benthopelagic fishes were sampled during three cruises to Seine Seamount, NE Atlantic, using bottom trawls and an epibenthic sledge. A total of 16 fish species were caught on the summit plateau of the seamount at 160–180 m depth, belonging to 15 different families. Four species were common to all types of trawls, whereas the other species were foun...

During different seasons of the years 2003–2005 in the NE Atlantic, zooplankton were sampled with a MOCNESS (multiple opening/closing net and environmental sensing system, mesh size 333μm) above the slopes and summits of Seine, Sedlo and Ampère seamounts and at remote reference sites outside the influence of the seamounts (far field). Wet weights o...

During an expedition in September 1998 zooplankton was sampled over the plateau and on the slope of the Great Meteor Seamount, using a Longhurst-Hardy Plankton Recorder. Sound scattering layers were observed with the ship's 33 kHz echo Sounder. Higher biomass and a slightly different composition of zooplankton groups were found on the Upstream side...

Benthopelagic nekton were sampled by trawl and baited trap arrays at two abyssal stations (WAST and CAST) in the northern Arabian Sea. The natantian decapod Plesiopenaeus armatus and fishes comprised most of the nekton caught by the trawls, whereas the amphipod Eurythenes gryllus dominated in the trap samples. At station WAST, Plesiopenaeus armatus...

Deep-sea benthopelagic fishes were sampled by trawl and free-fall longline at two latitudinally and bathymetrically separated stations in the northeastern Atlantic. The catch structure and the contents of the fish stomachs were analysed. The northern, 3000 m deep station in the Iceland Basin exceeded the deeper (4500 m) site in terms of demersal fi...