Acoustic Research In Algoa Bay
By Sarah Taudien

Raggy Charters were very excited to be part of a research project in November 2019 with Warren Tarboton as skipper, taking Elena Schall and Sarah Taudein around the Bay. Read the full story by Sarah Taudien:

Combining environmental DNA analysis and passive acoustic monitoring to explore marine mammal diversity

From November 14 until November 18 2019, Elena Schall and Sarah Taudien, PhD students at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI, Bremerhaven, Germany) and Helmholtz Institute for Functional Marine Biodiversity Research at the University of Oldenburg (HIFMB, Oldenburg, Germany), visited South Africa and Nelson Mandela University to conduct a collaborative short pilot study. Raggy Charters supported this scientific project by facilitating the sampling survey with their 28-foot catamaran “Winkle” and their crew.

This collaborative pilot study between the Nelson Mandela University (NMU, Port Elizabeth; South Africa), AWI and HIFMB analyzed marine mammals by using an integrative research approach. The majority of the marine mammal species are both highly vocal and do have available genomic data entries within sequence reference databases. This forms the basis for environmental DNA (eDNA) analysis and passive acoustic monitoring (PAM), both representing powerful non-invasive methods for the identification and description of species presence and species composition within marine environments. PAM uses sounds of marine mammals which are produced for communication and echolocation and identifies species by their specific vocalizations. Acoustic metrics then summarize how acoustic information is distributed within the analyzed environment and allow for species diversity assessments. eDNA analyses use DNA fragments, which are shed from target organisms into the environment, as a proxy for the presence of organisms through identification of genetic loci by comparison to sequence reference databases. These genetic analyses allow for presence/absence analyses, give insights into species communities and supply to some extent basic information on species abundance, species richness and their biomass.

The integrative study on marine mammals in Algoa Bay (Port Elizabeth) aims to overcome blind spots of these newly applied non-invasive techniques. For PAM, animals that produce no vocalizations during the time of measurement or that produce undescribed vocalizations hamper the passive acoustic species identification. For eDNA analyses, more detailed studies are needed to understand the resolution of spatial and temporal scales of eDNA distribution within the marine environment as several physical processes influence eDNA persistence and its fate within the environment. During the four sampling days, several pods of bottlenose dolphins and two Bryde`s whales have been spotted by the aid of the crew of Raggy Charters. At each sample spot, both analyses have been conducted and the data will be analyzed in collaboration of NMU, AWI and HIFMB. Our research interest of identifying marine life by non-invasive biomonitoring and conservation agreed well with the concept of Raggy Charters focusing on marine eco-tourism and environmental education.

Pictures by Sarah Taudien