Key research into Algoa Bay dolphins

NMMU team focuses on endangered humpback species

FINDING out why Algoa Bay has unusually large pods of common and bottlenose dolphins is at the heart of Dr Stephanie Plön’s research. Plön is from the Department of Oceanography in the School of Environmental Sciences at NMMU.

She and her research team often have four or five sightings a day of groups ranging from 10 to 15 Indian Ocean bottlenose dolphins to several hundred long-beaked common dolphins.

The sightings are often associated with bait balls or large schools of sardines or red eyes (part of the herring family).

“It is amazing and overwhelming; it’s like a mini sardine run,” Plön said.

“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.”

Her research team includes four PhD students, three MSc students and one postdoctoral fellow.

Three or four of them go out to sea at a time, spending up to 10 hours in a 6m semi-rigid inflatable, taking field notes and photographs.

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.

The estimate is that the population has dropped to under 1 000 in South African waters.

Updated population research on these dolphins is therefore of critical importance and in June last year postdoctoral researcher Dr Thibaut Bouveroux started his research on the humpback dolphins in Algoa Bay under the guidance of Plön.

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.

Plön said the humpback dolphin was an extremely shy animal that was easily disturbed.

“These animals live within 500m of the shore where there is a lot of human activity. This might have a negative impact on their reproductive rate or food abundance,” she said.

“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 lookout for them and keep their distance.” Plön said Algoa Bay was ideal for research on dolphins and also whales for a number of reasons.

These included the presence 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.

Established in the 1960s, the collection has been put together from dolphin and whale strandings, and animals incidentally caught in shark nets along South Africa’s coastline.

“Our dolphin and whale species are not only important in their own right, they are also a key indicator species for overall ocean health because they are at the top of the marine food chain,” Plön said.

“Research on them informs the decisions and actions required to sustainably conserve our oceans and marine species.”

Originally from Göttingen, Germany, Plön completed her undergraduate degree in marine biology at Swansea University in the United Kingdom.

She moved to South Africa in 1994 as a result of her interest in dolphins and whales and completed her master’s and PhD at Rhodes University, followed by postdoctoral research in New Zealand.

She settled in Port Elizabeth in 2005 to pursue research on dolphins and whales along the Eastern Cape coast.

One of her 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 or 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,” Plön said.

Over the past seven years, Plön and her team have also been researching the pathology of stranded Indian Ocean dolphins.

Since 2009, parasite lesions have been detected in all the dolphin species. The specific parasite has yet to be identified, but marine parasites are increasingly being linked with ocean pollution.