Algoa Bay in South Africa’s Eastern Cape has unusually large group sizes of common and bottlenose dolphins. The reason for this is being researched by dolphin and whale (cetacean) specialist, Dr Stephanie Plön, an ocean health researcher from the Earth Stewardship Science Research Institute at Nelson Mandela University in Port Elizabeth.
“My research team and I often have four or five sightings a day of groups ranging from 10 to 15 ‘Bottlenose’ or Indian Ocean Bottlenose Dolphins to several hundred ‘Common’ or Long-Beaked Common Dolphins, often associated with bait balls or large schools of sardines or red eyes (part of the herring family). Sometimes these bait balls are a kilometre in diameter,” explains Dr Plön.
“It is amazing and overwhelming; it’s like a mini sardine run; the water is literally boiling with dolphins and gannets, and, among all this you’re trying to observe and photograph the dolphins, because we need to identify individuals for our research, from notches or marks on their dorsal fins.”
Dr Plön explains that Algoa Bay is ideal for novel research on dolphins and also whales for a number of reasons, including the presence of large numbers of several cetacean species, and the marine mammal collection at the Port Elizabeth Museum, which is the largest in the Southern Hemisphere and third largest in the world. It is a fascinating, invaluable repository for marine scientists worldwide.
“Our dolphin and whale species are not only important in their own right, they are key indicator species for overall ocean health because they are at the top of the marine food chain. Research on them informs the decisions and actions required to sustainably conserve our oceans and marine species,” says Dr Plön, who has researched the Eastern Cape Coast and Algoa Bay’s dolphins, whales and marine environment since 1995. “We know so little about the extraordinary marine world and I am interested in finding out about the unknown.”
One of the team’s most recent research areas is to determine how far dolphins travel from Algoa Bay during the annual sardine run. They are comparing this to where and how far they travel outside of the sardine run, which starts off East London in late May/early June and moves up the coast to Durban.
“There is some scientific debate as to whether the sardine run actually starts in Algoa Bay, but it has not been confirmed,” says Dr Plön. “What we certainly do have are bait balls and all this research helps to inform us about the dolphins’ diet, which includes reef and estuarine fish species, and whether these populations are stable or decreasing.”
Over the past seven years, Dr Plön and her team have also been researching the pathology of stranded Indian Ocean dolphins and comparing them to the dolphins incidentally caught in the KwaZulu-Natal shark nets.
“We know that strandings are in most instances a result of the animal being sick, whereas the by-catch animals should be reflective of the normal, wild population. The pathology investigation therefore significantly assists us in assessing the general health of South Africa’s oceans.”
Since 2009 parasite lesions have been detected in all the dolphin species, and both in the stranded animals as well as those caught in the shark nets. The specific parasite is yet to be identified, but marine parasites are increasingly being linked to ocean pollution.”
Indian Ocean Humpback Dolphin is Endangered
While Algoa Bay’s Bottlenose and Common dolphin populations appear to be healthy, the Indian Ocean Humpback Dolphin is in serious trouble. It is now classified as ‘Endangered’ according to the 2015 Red Data Book of Mammals of South Africa (in press). The estimate is that the population has dropped to under 1000 individuals for South African waters.
“The most recent research on the population size of the Indian Ocean Humpback Dolphin was in 1991 – 1994 when it was estimated that approximately 460 individuals resided in Algoa Bay,” explains Dr Plön. “This indicated that historically it was the largest population in South African waters. Comparisons with current data suggest that their group sizes are down by half.”
Updated population research on this dolphin is therefore of critical importance and in 2016 postdoctoral researcher in the Department of Oceanography, Dr Thibaut Bouveroux, pursued his research on the Indian Ocean Humpback Dolphins in Algoa Bay, which he started in 2015.
The population decrease could be related to a decrease in food availability and/or a range of human impacts – from shipping and fishing to pollution and paddle skis. Dr Plön explains that the Indian Ocean Humpback Dolphin is an extremely shy animal that is easily disturbed:
“These animals live in the coastal zone within 500 metres from the shore where there is a lot of human activity, and this might have a negative impact on their reproductive rate or food abundance. Even paddle skiers surprise them when they get within a few metres of them, which is why I always advise paddle skiers to be on the look out for them and keep their distance,” explains Dr Plön, who skippers the research raft and has two years of training with the National Sea Rescue Institute (NSRI) in Port Elizabeth. It’s compelling but rigorous work as the researchers spend up to ten hours in a six-metre semi-rigid inflatable, taking field notes and photographs.
Human impact on baleen mother-calf pairs
PhD student Renee Koper from the Netherlands did her Master’s on Humpback Dolphins in Algoa Bay through Groningen University, supervised by Dr Plön. For her PhD she is currently doing novel research on the human impact on marine mammals, examining the potential impact of fishing traffic on baleen whale mother-calf pairs, particularly in relation to Coega’s deep-water port, which is now operational and will become increasingly active.
Baleen whales are adversely affected by the ‘masking effect’ of low-frequency noise from shipping, which blocks out the whales’ acoustic calls. She is researching how this affects cow-calf pairs, as it is not yet known whether they communicate vocally or by touching or both. Increasing human impact on the marine environment could potentially have an adverse effect on whale calves bonding with their mothers. She has put acoustic loggers in Algoa Bay and also in St Francis Bay as a comparison, as there is no commercial shipping there.
Sighting and re-sightings of Bottlenose Dolphins
Titus Shaanika started his MSc on bottlenose dolphins in Algoa Bay in 2016, supervised by Dr Plön and working with photos of Bottlenose Dolphins collected in Algoa Bay between 2008 and 2011 from the survey she undertook. He is interested to see if he re-sights individual dolphins (which may be resident in Algoa Bay) or if they are only seen once and are therefore simply passing through the Bay. He has already identified a large number of dolphins and his research will help to establish population size and structure of the dolphins found in Algoa Bay and Eastern Cape waters.
Information sharing at Bayworld
“South Africa’s marine environment is a global biodiversity hotspot,” she says. “Far more needs to be done to raise awareness about this incredible natural heritage, and the need to experience it and conserve it,” says Dr Plön. To share information about dolphins and whales, her team hosts exhibitions at Port Elizabeth’s oceanarium, Bayworld. They also give talks to ocean-focused sectors, such as the Surfski Club and Coega Environmental Management Committee, and they lead workshops for Eastern Cape Parks and Tourism rangers to promote citizen awareness about dolphins and whales, and dolphin and whale watching.
The Port Elizabeth Museum
The world’s third largest marine mammal collections
Dr Plön has been involved with the Port Elizabeth Museum since 1993, first as a student, utilising the large marine mammal research collection, known as the Graham Ross Marine Mammal collection, for both her BSc Hons from the University of Swansea, United Kingdom, (on a mass-stranding of common dolphins at Hluleka Nature Reserve, Eastern Cape), for her PhD degree from Rhodes University (‘The natural history of pygmy and dwarf sperm whales (Kogia spp.) from Southern Africa’), and later as a scientist and research associate with the museum.
The collection, which was established in the late 1960s, is the largest marine mammal collection in the Southern Hemisphere and the third largest in the world, and thus holds important material for a number of marine mammal taxa. These resources are particularly important for those species of marine mammals that are difficult to study. In addition, it reflects the high marine biodiversity we find off the Eastern Cape coastline.
Says Dr Plön: “Between 2005 and 2008 I was employed as curator/ research scientist at the Port Elizabeth Museum to advise on the collection and the captive dolphins. During that time, I strengthened the existing research agreement with the KwaZulu-Natal Sharks Board, which had been in place since the late 1970s, to collect data and samples for research purposes from the dolphins incidentally caught in the shark nets off KwaZulu-Natal. I also re-established the examination of stranded dolphins for research purposes and initiated teaching of marine mammal biology to zoology and veterinary students.
“Over the past 12 years, I have supervised and co-supervised numerous postgraduate student projects (both with Rhodes University and Nelson Mandela University), utilising the material from the collection. Since joining Nelson Mandela University in 2013, I have remained a research associate with Bayworld and the Port Elizabeth Museum, and I continue to teach a number of courses to veterinary students about marine mammal research at Bayworld/Port Elizabeth Museum throughout the year. I also still participate in stranding response and necropsies of marine mammals (which we have now expanded to include seals) and partake in the annual research trip to the KwaZulu-Natal Sharks Board to necropsy dolphins incidentally caught in the shark nets.”