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Exploring the tropical abyss of Sodwana Bay

By Gustav Rautenbach, Intern, SAEON Egagasini Node
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The African Coelacanth Ecosystem Programme (ACEP)* provides researchers with infrastructure and funding to explore and delve into the vibrant east coast of South Africa.

From the ACEP programme stems the Canyon Connection Cruise, which aims to better understand the influence of the Agulhas Current on the biodiversity of the north-east coast of South Africa. The cruise is led by Dr Jean Harris, skipper of the renowned research vessel Angra Pequena.

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The research vessel Angra Pequena in Sodwana Bay (Photo: Jason Boswell via Facebook) (ACEP: Canyon Connection Cruise)

The journey

On 26 May 2018 we departed from Durban harbour on the Angra Pequena. After a full day’s steam, we reached our destination, Sodwana Bay, set to be our home for the next four weeks. Unfortunately, the trip was interrupted several times due to freak weather conditions and rough seas.

We had to seek shelter in Richards Bay within the first week, and in Durban’s port during the second week. Despite the rough seas and traitorous weather conditions, the team’s spirit remained cheery as we were blessed by the East Coast’s striking landscapes and abundant mammalian activity.

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Crew prepare deployment of the ROV (ACEP: Canyon Connection Cruise)

Coelacanth spotted in Sodwana Bay from ROV (ACEP: Canyon Connection Cruise)

Science activities

A wide range of oceanographic sampling techniques were conducted to better understand the influence of the Agulhas Current on the biodiversity of the north-east coast. Sampling took place at Diepgat and Wright submarine canyons located around the Sodwana Bay region.

Conductivity, temperature and depth (CTD) casts took place at the canyon heads and upstream from the canyon head to investigate the ocean environment in and around the canyons. Water bottle samples collected by the CTDs underwent filtration to obtain chlorophyll and nutrient samples.

Furthermore, nets were towed to capture phytoplankton and zooplankton samples. Additional live video footage was collected using a remotely operated vehicle (ROV) piloted by Ryan Palmer from the South African Institute for Aquatic Biodiversity (SAIAB) and coordinated by Dr Kerry Sink, South African National Biodiversity Institute (SANBI) programme manager.  

Searching for number 33

Apart from all the science conducted during the cruise, we were on a mission to film the fossil fish, the Coelacanth. Once thought extinct, it was rediscovered in the early 1970s by Peter Timm in Sodwana Bay.

As of yet, only 32 individual Coelacanths have been spotted within South African waters, all of which were identified within the deep abyss of Sodwana Bay. Dr Kerry Sink and the rest of the science team were determined to find Coelacanth number 33 to propose monitoring programmes for the protection of this invaluable species. To make matters even more interesting, WildOceans, a marine protection programme funded by WildTrust, orchestrated the documentation of the search.

Sadly, no Coelacanths were found during the time I was on board the RV Angra Pequena; however, two days after my departure a Coelacanth was spotted. Whether it was Coelacanth number 33 has yet to be confirmed.

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The CTD is launched to collect oceanographic parameters and water samples (ACEP: Canyon Connection Cruise)

Gustav filters water samples from the CTD to obtain chlorophyll and nutrient samples (ACEP: Canyon Connection Cruise)

Personal experience

Working on a small vessel such as the RV Angra Pequena handed me the opportunity to gain a great deal of first-hand experience in oceanographic sampling techniques. Since the crew on board was very small, everyone got involved in the sampling, so we were exposed to a much greater variety of sampling techniques and interesting equipment than on larger research vessels. The crew members were particularly friendly and always willing to lend a hand where necessary.

My time on board the RV Angra Pequena was an unforgettable experience and the knowledge I gained from this expedition has been invaluable.

* ACEP is a multi-disciplinary, multi-institutional programme which serves as a fundamental research platform to the science community.

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