An estuary is where the river meets the sea, and plays an important role in the life of many animals. Throughout the day, week or year the physical and chemical variation can change dramatically. The major source of this variation is the tidal fluctuations. This means that the animals that live in these environments must be able to cope with these drastic changes in salinity, temperature and water level, making them very unique and special creatures.
Many juvenile fish migrate into the estuaries during late winter, spring and early summer. This is when the water temperatures are high and the food supply is abundant. The juvenile fish are better protected from most marine predators in the estuaries and therefore rely on these habitats in order to survive into adolescence. They return to the open ocean when they are big enough. (Wallace JH, “South African Estuaries and their importance to fishes”, South African Journal of Science 80, 203-207 (1984).
Human activities can have severe effects on estuaries resulting in the loss of biological diversity. Some of the most common problems include dredging, pollution and accelerated sedimentation due to erosion. If we want the estuaries and the species that thrive there to survive we must limit these destructive activities as much as possible.
ORCA TIMES- Quarterly report: January - March 2019
RESEARCH & MONITORING Bumper breeding season for Robberg seals? Between January-March volunteers assisted biologists with six boat-based counts of Cape fur seals that haul out on Robberg Peninsula. Apart from routine counts of adult seals, which have levelled off since 2012 despite seasonal fluctuations in their numbers, our biologists were surprised by the large increase […] Continue Reading...
EDUCATION- Overview!
Education- Siyakula Pre-School Education Once a week, volunteers visit young children at the local crèche to give a lesson on basic English words based on the theme of the week. All teaching is done in English (translated by the teachers into their mother tongue of isiXhosa) so that kids can learn a second language. It […] Continue Reading...
CONSERVATION Overview!
Conservation- Beach Clean-Ups We regularly hike along Plettenberg Bay’s beaches to remove marine debris. Unfortunately we live in a world where people still expose of their rubbish from vessels, in rivers or on beaches. This often causes deadly entanglement in marine animals. Tiny plastic particles (micro-plastics) are also known to end up in the ocean […] Continue Reading...
RESEARCH- Overview!
RESEARCH Overview The ORCA Foundation offers a unique learning experience for volunteers who are passionate about the marine environment. It will allow you to make valuable contributions to increased knowledge, awareness and conservation efforts while supporting applied marine research. As part of our comprehensive volunteer programme, you will regularly receive the opportunity to assist our […] Continue Reading...
The origins of marine mammals
The origins of marine mammals Although all marine mammals evolved from land mammals, it may surprise some that each group of marine mammals has its own unique ancestry. There are three groups of marine mammals: the cetaceans (whales, dolphins and porpoises), the pinnipeds (fur seals, sea lions, walruses and seals) and the sirenians (dugongs and […] Continue Reading...
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