Whales as indicators of ocean health

You’ve heard a little about the smallest and most numerous life forms in the oceans from Jon and Verity. But what about some of the most endearing (and largest) inhabitants? What can apex predators such as whales and dolphins tell us about the health of our oceans?

“From the poles to the equator, marine mammals such as seals, dolphins, and whales, play an important role in global ecosystems as apex predators, ecosystem engineers, and even organic ocean fertilisers. They occupy a diverse range of habitats, from deep sea environments to the Earth’s rivers and coastlines, and continue to astound us with their natural beauty.” Dr Jon Tennant.

Stephanie Plön is a cetacean researcher based in the Africa Earth Observatory Network at Nelson Mandela University. In this video Stephanie visits the Bayworld Museum in Port Elizabeth, which is home to one of the largest marine mammal collections in the world. At least 30 different species of whales and dolphins are represented there by over 5,000 specimens.

Stephanie explains why the Algoa Bay area around Port Elizabeth is so important for research and describes some recent studies which include the general ecology, diet, reproduction and taxonomy of whales and dolphins.

The ocean off the coast of South Africa is recognised as a biodiversity hotspot. Every year the phenomenon of the sardine run sparks a mass feeding frenzy in Algoa Bay. In addition, the area is undergoing major changes with increasing coastal development and deep water ports being built or expanded. Parts of the deep sea are also being explored for oil and gas.

One of the results of a 3 year survey to understand whale distribution in space and time through the Algoa Bay was the discovery of new nursery area for whale mothers and calves. As whale populations start to grow after the whaling ban, old areas are being recolonised but little is known about the bonding processes between mothers and their babies.

Whales are sensitive to shipping noise due to low frequencies (more about that in the next step) so what potential impact could a new deep water port have on mothers and calves? It could drive them away from these nursery areas or, if the whales aren’t sufficiently undisturbed by the port activity, it could lead to an increased risk of shipstrike.

Stephanie’s research uses a combination of the extensive Bayworld marine mammal collection and studies of the live whales and dolphins in the bay to establish what is normal variability in a population. In doing so, researchers are able to then study multiple and cumulative impacts such as pollutant levels, parasites and availability of prey.

Your task (optional)

The Ocean Data Viewer also includes data about whale and dolphin distributions in 2013. This time you can choose the filter for the cetacean species that interest you most. You can choose from:

• Sperm whales
• Sei whales
• Bowhead whales
• Northern Bottlenose whales
• Atlantic Spotted dolphins
• Melon-headed whales
• Hector’s dolphins

Open the Ocean Data Viewer.

Share your observations and thoughts in the comments below.