March Update: Removal of trawling net, 3D printed reefs, new deep-sea lander and shark behaviour research

Large fishing net found and removed by BCSS team

The BCSS team recently found a bottom trawling net in the Bazaruto Archipelago. The net measured 32m in length and was removed from the waters east of Bazaruto Island, as soon as the team spotted it. Trawling nets are detrimental to a vast amount of marine life. The nets are designed to target large schools of fish, however, the by-catch often consists of larger species such as sharks and turtles. Head over to our Instagram to read more about bottom trawling nets.

“The net was probably intended to trap and capture everything from the sandy and muddy seafloor. Fishermen drop them out into the far sea to then draw them into shore slowly. They can be as large as 200m long. The one we found could have easily caught bigger marine life like turtles, sharks or rays.” – Dr. Mario Lebrato, Chief Scientist at BCSS

Marine Operations Manager Mauro Jije measuring the found net. 

Schematic overview of a trawling net.

Volunteers and Interns Contributing to New Marine Science Project

Last month, the volunteers and interns at BCSS enjoyed a lecture about the oceanography of the Mozambique Channel and the rationale behind the ReMoTURB project. ReMoTURB is a research project from the Instituto Oceanografico de Moçambique in partnership with the Nelson Mandela University in Port Elizabeth, South Africa. The project concerns recruitment success in Mozambique fisheries in a highly turbulent shelf ocean ecosystem and climate change. The aim is to develop an integrated understanding of the coastal/shelf system, including the role of physical drivers, biogeochemistry, productivity, biodiversity and ultimately to relate these to fisheries and coastal communities.

The BCSS Ocean Observatory contributes data to the research through our open data system and last month the team and volunteers explored several reefs in the Bazaruto Archipelago to decide on an ideal study for ReMoTURB. The next step is to map the reef profiles so a 2D image can be designed to help plan for the sensors placements.

BCSS Providing Data for New Publication on Shark Behaviour in Mozambique

A publication is currently being written on shark behaviour in the Bazaruto Archipelago and beyond. Working together with Underwater Africa, the founder of the organisation, Calum Murie, has been collecting data on various shark species with the help of the BCSS Ocean Observatory and logistics. The data has been retrieved using VEMCO receivers installed by BCSS, which monitor movements of species like bull sharks and oceanic blacktip sharks. The research is being conducted as part of Murie’s PhD under the University of Chester.

“We are aiming to continue the research on sharks to uncover more details about their movements and critical habitats to foster more protection for their populations.” – Calum Murie, founder of Underwater Africa

Calum Murie working on a shark before harmlessly installing a V16 transmitter unit.

3D-printed Artificial Reefs Testing Outside the BANP

The BCSS team have previously developed artificial reef structures made out of natural materials such as sand and seawater, using sister property, Kisawa Sanctuary’s 3D printer. Last month, the team took the artificial reefs into the ocean for testing purposes. The main objective was to observe how marine life responds to the structures, and fortunately, the objects attracted a wide array of marine life colonising them within a small amount of time. The team will continue to test the structures in different habitats, monitoring the behaviour of fish species around them. Inspired by the UN Decade on Ecosystem Restoration, aiming to prevent, halt and reverse the degradation of ecosystems on every continent and in every ocean, we consider the results of the first testing rounds a success.

Testing of 3D printed artificial reefs on seabed.

Development of Deep Sea Lander with Cameras and Sensors to Study Marine Biodiversity

The BCSS field station has recently received deep-sea rated lights and batteries, which allows us to develop a new lander. The lander consists of a metal landing platform, a camera set up, light strobe with 72h of continuous light and a structure of sensors. The team is currently developing the platform with help of interns and volunteers. The next step would be to test in the on-site test tank, and eventually in the ocean. The goal of the platform is to monitor marine biodiversity at a depth of 200m. The platform would give us valuable information and data on marine life habitats in the deep-sea.

BCSS Analysing Fossilised Forests, Retrieving C/N Isotopes and C/N Percentage Analyses

The team has been analysing samples from fossilised forests found near BCSS, retrieving 14C, C/N isotopes and C/N percentage analyses to be conducted in BCSS’s partner laboratories in Europe. The findings are being analysed within an exploratory project of how terrestrial habitats convert themselves into marine ecosystems during time and sea level rise. Besides, exploratory data on which type of animals utilise fossilised forests found at sea was also gathered.

Analysing of fosiled forests near BCSS research station.

New Paper on Dead Gelatinous Plankton’s Contribution of Nutrients to Marine Ecosystems

Last month, BCSS submitted a new paper on how dead gelatinous plankton contribute food and carbon to marine ecosystems to Frontiers in Marine Science. The data on which the paper is based was retrieved in West Africa, and contains information about how gelatinous plankton contribute to the health of various underwater ecosystems. On site, the team has observed the arrival of jellyfish in the Bazaruto Archipelago and how they are being consumed by local animals, creating an efficient ecosystem where nothing goes to waste. BCSS has also studied how marine life feeds on gelatinous plankton in the deep-sea.

Wildlife Highlights

• 1 March:
A bowmouth guitarfish (Rhina ancylostoma) was spotted near St Sebastien at a cleaning station, and a grey reef shark (Carcharhinus amblyrhynchos) was sighted southwest of Benguerra Island at a cleaning station too.

• 2 March: A reef manta ray (Manta alfredi) was seen on the surface southwest off Benguerra Island.

• 19 March: A school consisting of more than 30 devil rays (Mobula mobular) was spotted northeast of Benguerra Island.

• 20 March: A large pod of bottlenose dolphins (Tursiops truncatus) was sighted on the surface northeast of Benguerra Island.

• 20-30th March: Large aggregations of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) were observed in the area south of Benguerra Island in waters deeper than 100m. Bull sharks (Carcharhinus leucas), oceanic blacktop sharks (Carcharhinus limbatus) and dusky sharks (Carcharhinus obscurus) were also seen in that area. Black marlins (Istiompax indica) are still being sighted regularly, while sailfish (Istiophorus platypterus) and wahoo (Acanthocybium solandri) season is about to start.

21 March: A dugong (Dugong dugon) was seen surfacing at the south point of Bazaruto Island.

• 22 March: A reef manta ray (Manta alfredi) was spotted on a dive in the St Sebastien area.

• 23 March: A grey reef shark (Carcharhinus amblyrhynchos) was seen at the north point of Bazaruto Island.

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