Krakatoa is still active, and we are not ready for the tsunamis another eruption would generate

Deni_Sugandi / shutterstock

Ravindra Jayaratne, University of East London

The August 1883 eruption of Krakatoa was one of the deadliest volcanic explosions in modern history. The volcano, found in the middle of the Sunda Strait in between two of Indonesia’s largest islands, was on a small island which disappeared almost overnight. The eruption was so loud it could be heard in Reunion, some 3,000 miles away.

As the volcano collapsed into the sea, it generated a tsunami 37m high – tall enough to submerge a six-storey building. And as the wave raced along the shoreline of the Sunda Strait, it destroyed 300 towns and villages, and killed more than 36,000 people.

Nearly 45 years later, in 1927, a series of sporadic underwater eruptions meant part of the original volcano once again emerged above the sea, forming a new island named Anak Krakatoa, which means “Child of Krakatoa”. In December 2018, during another small eruption, one of Anak Krakatoa’s flanks collapsed into the ocean and the region’s shorelines were once again hit by a major tsunami. This time, 437 were left dead, nearly 32,000 were injured and more than 16,000 people were displaced.

Map of Krakatoa.
Krakatoa is in the middle of a narrow strait between Java and Sumatra. Indonesia’s capital Jakarta is about 100 miles to the east.
ChrisO wiki / CIA World Factbook / Demis

Even though Anak Krakatoa had been active since June that year, local residents received no warning that a huge wave was about to hit. This is because Indonesia’s early warning system is based on ocean buoys that detect tsunamis induced by submarine earthquakes, such as those that struck on Boxing Day in 2004, in one of the most deadly natural disasters of all time.

But tsunamis caused by volcanic eruptions are rather different and, as they aren’t very common, scientists still don’t fully understand them. And Indonesia has no advanced early warning system in place for volcano-generated tsunamis.

At some point in the future, Anak Krakatoa will erupt again, generating more tsunamis. Since it is difficult to predict exactly which areas of the Sunda Strait will be affected, it is of paramount importance that residents in coastal villages are well aware of the danger.

Damaged buildings on a seafront, tropical forest background.
The tsunami badly damaged buildings on Legundi island, 20 miles from Krakatoa.
Ravindra Jayaratne, Author provided

An advanced early warning system could be installed. It would involve tide gauges to detect an increase in water levels, satellite imagery and drone mapping, and a tsunami numerical model run in real time. When this system triggered a warning, it would be fed direct to residents who live in the coastal belt. Until such a system is in place, it will be vital to get the local community involved in disaster risk management and education.

We need to tell people about the risks

But preparing for future disasters isn’t just about building breakwaters or seawalls, though these defensive structures are clearly vital for preserving beaches for tourism and local businesses like fishing. It is also about educating people so that they feel psychologically healthier, more resilient and less anxious about facing the mega tsunamis of the future.

I have previously highlighted two examples of proactive community participation in disaster-prone villages in the UK and Japan. In both cases, residents know how to act in case of a natural disaster without depending on the authorities. It is certain that the decimation of the land and deaths could be reduced if the local communities are well prepared for natural disasters like tsunamis.

Three men hold up a tsunami evacuation route sign.
Head to the hills.
Ravindra Jayaratne, Author provided

Following the December 2018 Anak Krakatoa tsunami, local researchers and I conducted a detailed field survey of the coastline of Lampung province, on the north side of the strait, and some of the smaller nearby islands. We found a lack of proper tsunami defence structures or any early warning system, and houses and businesses built very close to the coast with no buffer zone. We identified high ground where residents could run to in case of a tsunami and put up signs with evacuation routes.

During this survey, I conducted a series of focus group meetings with local residents and businesses in order to make the communities more resilient and reduce their anxiety about future mega tsunamis in the area. I developed a tsunami wave propagation model to replicate the 2018 tsunami and most plausible future tsunami events, and to identify the most vulnerable coastal stretches, such as the village of Kunjir on the Lampung mainland.

I also combined field survey results, numerical model outputs and published information to make some recommendations for local communities. I suggested active collaboration between government departments and local institutions on the issue, and the formation of disaster preparedness teams for every village in Southern Lampung. The planning criteria for development of infrastructure along the coasts should also be put under review, and there should be a trauma healing programme for the victims of the 2018 Krakatoa tsunami.

We don’t know exactly when Krakatoa will next erupt, or if any future eruptions will match those of 1883 or even 2018. That’s a question for volcanologists. But we should do what we can to prepare for the worst.The Conversation

Ravindra Jayaratne, Reader in Coastal Engineering, University of East London

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Only two northern white rhinos remain, and they’re both female – here’s how we could make more

White rhinos owe their name to the Afrikaan word ‘weit’, meaning wide, which refers to the animal’s wide mouth.
Vladislav T. Jirousek/Shutterstock

Ruth Appeltant, University of Oxford and Suzannah Williams, University of Oxford

There were fewer than 100 southern white rhinoceroses (Ceratotherium simum simum) a century ago. Today, there are over 20,000. Sadly, this success story only stretches as far as the southern subspecies of the white rhino. With the death of the last male in 2018, the northern white rhinoceros (Ceratotherium simum cottoni) has passed the point where it can be saved naturally. With only two females remaining, the subspecies is now classed as functionally extinct.

Historical distributions of the northern (red) and southern (green) white rhino.
Tunstall et al 2018, CC BY

This is a poignant, but not entirely hopeless, situation. New techniques, such as in vitro fertilisation (commonly known as IVF), enable us to bypass normal reproduction to produce new northern white rhino babies. Sperm samples from deceased males that are preserved in bio-banks solve one side of the equation, but there aren’t frozen stores of northern white rhino eggs that we can rely on as easily.

We established the Rhino Fertility Project at the University of Oxford to help solve this problem. By using ovary tissue from deceased female rhinos to grow lots of eggs for fertilisation in a lab, we think we may have found a way to save the northern white rhinoceros – and potentially, other endangered species – from extinction.

The first breakthroughs

A team led by Professor Thomas Hildebrandt from the Leibniz Institute for Zoo and Wildlife Research in Germany had a breakthrough in 2019 when they managed to collect eggs from the last remaining northern white rhinoceros females. After treating the females with hormones the immature eggs were collected, transferred to a lab where they were matured and then fertilised with frozen sperm.

To date, a handful of northern white rhinoceros embryos have been created this way. They’re frozen and awaiting implantation in a surrogate female southern white rhinoceros. Transferring embryos into surrogates to produce baby animals is a process that’s been well established for lots of species, including horses and cows, though it’s still in the development phase for rhinos.

But the biggest constraint on this approach is that hormonal stimulation of female rhinos produces just a few eggs per cycle. Not all of these eggs will fertilise and not all will develop into an embryo. After transfer to a surrogate, only some will complete their development and become baby rhinos. As you might imagine, with only two remaining rhinos to gather these precious eggs from, this limits our ability to revive entire populations.

So what if we had the means to produce more eggs? While eggs collected from female rhinos are in short supply, generating eggs from ovarian tissue from deceased rhinos could fill the gap.

Read more:
Coral sex: how reproducing species in the lab could be key to restoring reefs in the wild

Petri dish rhinos

As in humans, every female rhinoceros is born with thousands, if not millions, of immature ovarian follicles. At the centre of each of these sits an immature egg, also known as an oocyte. The follicle grows over months until it’s ready to ovulate. At this point, these contain fluid and secrete hormones which influence the menstrual cycle. Ovaries contain lots of these immature follicles that are just waiting to be activated – in fact, far more follicles than are actually needed. As follicles grow and some are selected for ovulation, many are lost.

A mass of white tissue (the follicle) within the surrounding pink ovarian tissue.
A follicle situated in the ovarian tissue of a southern white rhinoceros.
Ruth Appeltant, Author provided

Rhinos don’t undergo the menopause and so the ovaries of older animals still contain small follicles. Our goal is to grow these from the ovarian tissue of a deceased rhinoceros in the lab. We’re experimenting with techniques that maximise the number of follicles we can grow in a culture dish.

By harnessing the full potential of rhino ovaries, we aim to grow as many eggs as possible. We’re developing our method using ovarian tissue from different rhino species, including the southern white, Indian and black rhinoceros. Since all rhino species are either threatened or endangered, this technology could help more species than just the northern white, including the rare Javan and Sumatran rhinos.

A schematic that visualises the process described in the text, from deceased ovarian tissue, to new offspring.
How oocytes in follicles can develop into offspring by using in vitro ovarian tissue culture.
Ruth Appeltant, Author provided

But as you can imagine, there aren’t many rhinoceros ovaries available for laboratory research in the UK. Shipping tissue from threatened or endangered species in Africa to the UK in a timely manner is impossible, with many legal hurdles and mountains of paperwork. Collaboration between zoos, wildlife parks and research institutes is of the utmost importance here, to allow us to obtain this precious ovarian tissue.

The experience and knowledge we’re gaining by developing this technique could even be useful in conservation efforts for other species. By freezing ovarian tissue and sperm from other endangered species and developing methods to cultivate follicles in labs, we could prevent further losses of some of Earth’s most iconic wildlife and revive ecosystems rich in biodiversity.The Conversation

Ruth Appeltant, Postdoctoral Researcher in the Conservation of Endangered Species, University of Oxford and Suzannah Williams, Associate Professor in Ovarian Physiology, Lead for Ovarian Cryopreservation and Fertility Preservation Research, Lead of Rhino Fertility Project, University of Oxford

This article is republished from The Conversation under a Creative Commons license. Read the original article.