Blog

The world’s largest living fish

We had an interesting visitor into the Knysna lagoon recently, a whale shark Rhincodon typus. Whale sharks are very large, slow-moving filter-feeders which have a circumpolar distribution through all tropical and warm water, between 30°N and 35°S. The distribution of whale sharks is temperature dependent, and they are rarely sighted in areas with a surface READ MORE

An expert fisher

While the African fish eagle Haliaeetus vocifer is one of the more iconic bird species associated with water bodies, the Western osprey Pandion haliaetus is a species not to be overlooked. Luckily for us, here in Plettenberg Bay on the Keurbooms River we have both of these magnificent species! The Western osprey is a slender, READ MORE

The violet snail and its bubble raft

Amidst the seaweed, debris, and shells washed up on the beach, you may find a peculiar purple shell, with a thin, fragile shell, looking for all intents and purposes like a garden snail, except for its beautiful violet colour. This is the violet snail, or bubble raft shell, Janthina janthina, which, as a family (Janthinidae), READ MORE

Melon – but not the kind you’re thinking of

Toothed whales (Odontocetes) are unique among mammals – they are able to echolocate underwater. Echolocation is the specialised acoustic adaptation by animals who use sound to forage for prey, navigate, and avoid predators by emitting sounds and listening to echoes as the sound waves reflect off different objects in the environment. This requires morphological and READ MORE

Kelp gull – king of the trash heap?

The human population is increasing rapidly, and demands urban landscape development. Contemporary urbanisation is expanding in such a way that previously natural areas are usurped for expansive growth resulting in protected and natural areas becoming islands embedded in an urban mosaic. This increases the interactions between humans and wildlife in the area. Human refuse, and READ MORE

Seismic surveys – the full story?

Humans have moved into all areas of the world, and even if they are not present, evidence of them is. The marine environment is no different. Marine litter has been of foremost concern but there is growing interest and concern over anthropogenic noise in the marine environment. Seismic surveys, shipping, high power sonar, and echo READ MORE

Seismic survey effects on whales and dolphins

The ocean is a noisy place, as, unlike light and other possible stimuli, sound can travel very efficiently in seawater. Anthropogenic noise pollution in the marine environment is becoming a large concern – underwater noise created by ships and other human-related sources can be detected many kilometres away, far beyond what would be seen or READ MORE

What is a seismic survey?

A seismic survey is a method of investigating the subterranean structure, primarily used in search of oil and gas deposits. Marine seismic surveys have been performed since the 1950s when chemical explosives were used to create sound waves. In the 1960s airguns were developed and are now currently used for almost all seismic surveys. Airguns READ MORE

Cape eelgrass

You’re slowly cruising along the Keurbooms River when the boat motor sputters and dies, and once you pull it up out of the water, there clogged in the propeller is a clump of Cape eelgrass or zostera grass Zostera capensis. You’re swimming in the Keurbooms and something slides along your leg and gets tangled around READ MORE