New and renewed discoveries in our oceans

MUCH has been written about the disastrous effects of climate change upon our oceans which we can least afford to ignore. These include rising sea levels, the absorption of carbon dioxide and its acidification effects upon marine wildlife, and the destruction of kelp beds amongst many other concerns.

Amongst this ‘doom and gloom’ scenario it is refreshing to discover new scientific findings on the significance of Saharan dust on oceanic micro life, coral reef breeding, the rediscovery of a particular Bornean shark and the latest discovery of yet more species of shark, all of which I find of particular interest as I hope do my readers.

Saharan dust plumes in the Atlantic Ocean

Researchers at Florida State University, USA, have recently revealed their findings from the Atlantic seabed at chosen sites based on the distances from the Sahara-Sahel Dust Corridor running from Chad to Mauritania. This research study revealed that the dust contained particles of iron which have a significant impact on sea life the further it falls away from its source.

The iron in the sand particles, blown thousands of kilometres across the Atlantic Ocean, appear to be more bio reactive the further they travel. This was found in their analysis of iron in the seabed cores that they extracted which recorded how much dust had sunk to the seafloor. This airborne fertiliser dissolves quickly in seawater thus stimulating many organic organisms with a supply of nutrients and especially to phytoplankton. The research revealed that a lower amount of this bio reactive iron was found the further from its Saharan source thus suggesting from the rock core samples that marine life had extracted the iron from the ocean in greater quantities. This equated to where, in the Atlantic Ocean, significant blooms of phytoplankton are found through the process of photosynthesis.

Renewing life on coral reefs

Coral bleaching, through climate change, is a worldwide disaster yet, only a few years ago the late Professor Steve Oakley and his family set up the Tropical Reef and Conservation Centre (TRACC) in the Sulu Sea at Pom Pom Island near Semporna in northeast Sabah. There, they bred young corals in empty glass bottles before implanting them in holed concrete crates on the side of a former fishing dynamited, destroyed reef. Today fish and indeed sharks freely swim around the reef thanks to the very hard work of his marine biologist daughter, Hazel, and her colleagues. This innovative way of restoring coral reefs has inspired other marine biologists to try other methods.

A very recent study by the Sexual Coral Reproduction Research Centre (Secore International) based in Miami, Florida, has responded fast to the maritime heat that struck the Caribbean Sea in 2023 destroying most of the coral reefs there. Conservationists are using a form of in-vitro fertilisation (IVF) to breed coral in more than a dozen locations in nine Caribbean centres. By collecting coral spawn during a spawning night, a type of in-vitro fertilisation is used to produce vast numbers of little corals with a wide genetic diversity with the symbiotic algae attached to them. Thus, damaged coral reefs are being restored and these have been seen to be more resistant to marine bleaching.

Borneo shark (Carcharhinus borneensis)

Certainly, most people living in the coastal area near Mukah, Sarawak are familiar with this species even if most of us have never heard of it before! Our Bornean shark was first recorded in 1858 by Dr Pieter Bleeker, a Dutch military surgeon and ichthyologist based in Batavia (Jakarta). He based his observations on a shark caught off Singkawang in western Kalimantan. This rare species of shark is today classified as critically endangered on the IUCN Red List as it is now only found in the waters of the Mukah region. Once it was found as far afield as Zhoushan island, China, Java, and the Philippines.

It is a small grey shark reaching between 65cm and 70cm in length and is quite distinctive by its long pointed nose hence ‘rhinus’ in its Linnean classification. With a very slender shape, it has two dorsal fins. The front fin is large and triangular whilst its second fin is small and much lower. Feeding mostly on smaller species of fish, it produces five pups per litter, each measuring between 24cm to 28 cm in length. Very little is known about this rare and endangered species and yet more research is needed.

New shark species in ocean depths

By the mid-1980s, some 360 species of shark had been identified and today there are now 500 identified species with yet more to be classified. This vast increase in the number of species is due to increased human exploration of the deeper ocean chasms in our world combined with newer deep sea fishing methods. Many of these newly-discovered species live at depths of between 300m to 500m and at nighttime they swim upwards towards the surface waters where fish food is more plentiful and thus are more susceptible to commercial fishing. This is seen as ‘bycatches’ in fishermen’s nets for they have little commercial value.

In 1989, Australian marine biologists found off the Rowley Shoals (a group of atolls on the edge of the continental shelf in the East Timor Sea), leathery egg cases which some species of shark lay instead of giving birth like the Borneo shark to live young. These cases looked like the torsos of human skeletons with the central breast bones attached to the rib cages and were dispatched to various natural history museums in Australia and worldwide. It was not until the beginning of 2023 that the home scientists finally put together the pieces of the jigsaw puzzle as to from what sort of catshark these eggs originated.

Finally, a new species, the Demon catshark (Apristurus ovicorrugatus) was identified. It is thought that this newly-discovered species lives in deep water coral reefs at a depth of 700m, too deep for sunlight to penetrate.

Shark researchers share their thoughts and findings, and thus new species are recognised. Two new species of saw shark caught by local fishermen off the coast of southeast Southern Africa, Madagascar, and Zanzibar have now been identified. In 2021, shark researchers discovered three new species of deep sea sharks that glow in the dark with one growing up to 1.8m in length. Just less than half a century ago, divers found a strange shark entangled in the anchor of a US Navy warship off Hawaii. This ‘megamouth’ shark was 4.5m long and as a filter feeder swam with its jaws always open and now is considered as one of the largest growing species of shark.

There are yet more shark species and indeed fish species to be identified in our oceans, one of the few last places on Earth to be fully explored. It is refreshing to learn that further marine research is in progress and that bio-technological advances are gradually overcoming the results of climate change, which must be now considered as the ‘new norm’ and to which both we and nature must find ways to adapt.