World
Did toxic algae kill hundreds of elephants in Botswana?
An investigation into the sudden deaths of at least 350 elephants in Botswana in 2020 has revealed the cause was almost certainly a “toxic brew” of open water tainted by a species of cyanobacteria that released cyanotoxins, essentially contaminating the elephants’ watering holes.
According to researchers, approximately 20 watering holes in Botswana’s Okavango Delta had been contaminated across roughly 6,000sq km (2,316 square miles).
So what happened, and how?
What is cyanobacteria and how does it harm elephants?
Although not all cyanobacteria, commonly referred to as blue-green algae, is toxic, some cyanobacteria can produce a type of deadly algal blooms (HABs) in standing water. This is the type which was discovered in the investigation carried out by researchers at King’s College London.
The study showed that the African elephants (Loxodonta africana) died in May and June 2020 after drinking from water holes contaminated with these toxic algal blooms.
“Scientists believe that the production of cyanotoxins is related to certain environmental triggers, for example, sudden rise in water temperature, nutrient loading, salinity,” Davide Lomeo, Earth observation scientist at King’s College London, a collaborator with Plymouth Marine Laboratory and the Natural History Museum in London, and lead researcher in the recent study, told Al Jazeera.
How did the elephant deaths come to light?
In early to mid-2020, a series of routine aerial surveys conducted by helicopter by the conservation organisation, Elephants Without Borders, revealed multiple elephant carcasses scattered across the landscape of the Ngamiland district of northern Botswana.
The aerial survey showed 161 elephant carcasses and 222 sets of bones, while also counting 2,682 live elephants throughout the eastern region of the Okavango Panhandle. In addition, the distance between the dead elephants indicated the deaths had been sudden, rather than gradual.
“The strong clustering of carcasses also suggests that the event was sudden, with limited dispersal of elephants prior to death,” the authors of the study said.
How did researchers identify toxic algae as the cause of death?
Before researchers confirmed it was toxic algae which killed the elephants, they had to rule out several other probable causes.
“Although this area is a known poaching hotspot in Botswana, this was ruled out since elephant carcasses were found with tusks intact,” the authors of the study said.
Other initial theories included virulent and bacterial causes, such as encephalomyocarditis virus or anthrax, but the evidence taken from the field – such as the age of the dead elephants and the absence of any clinical signs of disease, meant the researchers ruled these out as the cause.
The distribution of carcasses and bones suggested a unique “spatial pattern”, which indicated that localised factors may have played a role in the mass die-off. This led to further exploration of specific environmental and ecological conditions in the affected areas.
There were several other factors that served as evidence that the elephant watering holes were to blame. Using satellite photos, researchers measured the distance the elephants walked after they drank from the watering holes – an average of 16.5km (10.2 miles). Many of the elephants died shortly thereafter, roughly 3.6 days (88 hours), after they drank from the nearby contaminated water holes.
The report states that 88 hours aligned with previously reported toxicological timelines for other large mammals which have died from blue algal poisoning.
In addition, Lomeo’s previous body of doctoral work investigating the history of mass-mortality events and water quality in waterbodies in Africa served as evidence to further look into the theory of water hole contamination.
“This event was what led to this idea, since it was a well-covered news at the time, but no one really knew why they died. I then applied my skills in geospatial and computational data science to investigate the event under a well-known set of methods typically applied in epidemiological investigations (eg COVID-19),” explained Lomeo.
What is still unknown about the elephant deaths?
It is impossible to measure the level of toxicity for each waterhole from aerial photos. In addition, it is unclear whether elephants drank from one watering hole or several, according to researchers.
“It is highly likely that they drank from multiple pans before their death. It cannot be established if the fatal intoxication occurred in a single drinking event, but it seems more plausible that if cyanotoxins were present and were the cause of the die-off, this was through toxins bioaccumulation in elephants’ organs,” stated the study.
Although it is clear that the toxic waterholes were the likely source of the elephants’ mass mortality, there remains some uncertainty about the findings due to the timing of the mass die-off.
“The event occurred during the COVID-19 movement restrictions, and timely intervention was not possible. Therefore, tissue samples [which would have confirmed the presence/ absence of cyanotoxins] were not collected. Post-mortem investigations also need to be done within a certain timeframe, beyond which samples would be too degraded. Additionally, cyanotoxins cannot be detected from satellites, so the links can only be but indirect,” Lomeo explained.
As the aerial data was collected considerable time after the deaths in March and May 2020 – researchers could not definitively rule out the involvement of other animals in the elephant deaths.
Furthermore, smaller creatures may have been missed in the aerial survey, potentially limiting scientists’ understanding of the full scope of the incident.
“The area is well-known for very high predation rates, meaning that animal carcasses disappear quickly because of scavengers like hyenas and vultures. Hence, the involvement of other animals cannot be ruled out,” Lomeo said.
The specific conditions that would produce the level of toxicity in a watering hole that would be lethal to surrounding animal species are also still unknown.
“There is still uncertainty. We know that certain cyanobacteria species are more likely to produce cyanotoxins, and we know which toxins each species typically produces,” said Lomeo.
According to the research, cyanotoxins exhibit significant variations in their potency and effects. Certain types are extremely toxic, capable of causing death even in very small concentrations. Others, while less immediately dangerous, may still pose health risks at higher levels without necessarily being lethal. The field of cyanotoxin research remains active, with many aspects yet to be fully understood and explored.
Despite this, the overall findings of the study have been widely accepted. “The cause of the die-off has been officially attributed by the Government of Botswana to environmental intoxication by cyanobacterial toxins, also known as cyanotoxins,” the study’s authors said.
Could this happen again?
Although mass deaths of elephants are rare, researchers cannot be certain it will not happen again and that it will only affect elephants or land animals.
“[In] all arid systems where animals are dependent on stagnant water in lakes/ponds are susceptible to this [mass die-offs], the aquatic life in lakes also can be harmed in this same manner. We have even seen this in rivers and oceans where high nitrification from agricultural run-off combined with warming temperatures leads to disastrous bacterial blooms,” George Wittemyer, a behavioural ecologist at Colorado State University, one of the institutes involved in a study in Kenya that revealed that elephants use individual names, told Al Jazeera.
While it was relatively easy for researchers to identify the elephant carcasses from the air due to their size, the sudden deaths of smaller animals might not be so easy to identify.
A 3-D rendering of an Iranian Shahed-136 drone, a device with two triangle-shaped wings attached to a central fuselage. It has an engine the size of a small motorcycle’s and carries 110 pounds of explosives.
Engine the size of a small motorcycle’s
Carries 110 pounds of explosives
One of the biggest takeaways of the war with Iran is that it has proven itself to be a surprisingly capable adversary against the United States. In addition to its willingness to go on the offensive, Iran has forced the U.S. and its regional allies to confront the rise of cheap drones on the battlefield.
Iranian drones, made with commercial-grade technology, cost roughly $35,000 to produce. That is a fraction of the cost of the high-tech military interceptors sometimes used to shoot them down.
Cheap drones changed the war in Ukraine, and they have enabled Iranians to exploit a gap in American defense investments, which have historically prioritized accurate but expensive solutions.
Countering drones has been a major priority for the Pentagon for years, according to Michael C. Horowitz, who was a Pentagon official in the Biden administration. “But there has not been the impetus to scale a solution,” he said.
In just the first six days, the U.S. spent $11.3 billion on the war with Iran. The White House and Pentagon have not provided updated estimates, but the American Enterprise Institute, a conservative-leaning think tank, estimated in early April that the U.S. had spent approximately between $25 and $35 billion on the war, with interceptors driving much of the cost. Many missile defense experts also fear interceptor stockpiles are now running dangerously low.
Here is a breakdown of some of the ways the U.S. and its allies have countered Iran’s drones, and why it can be so costly.
Air-based strikes
In an ideal scenario, an early warning aircraft spots a drone when it is still several hundred miles out from a target, and a fighter jet, like an F-16, is dispatched from a military base. The F-16 can then use Advanced Precision Kill Weapon System (APKWS) II rockets to shoot a drone from about six miles away.
A 3-D rendering of an F-16 fighter jet firing an APKWS II rocket from under one wing. Two to three rockets are fired per drone, as per air defense protocol. Two APKWS II rockets and an hour of F-16 flight cost approximately $65,000, a little less than twice that of the Iranian Shahed-136.
Two to three interceptors fired per drone
These types of defensive air patrols are cost-efficient, but haven’t always been available because of the vast scope of the conflict. Iran has also targeted early warning aircraft that the U.S. needs to detect a drone from that distance, according to NBC News.
The other option for detecting and shooting down drones is a variety of different ground-based detection systems, but these systems are all at a disadvantage, as their ability to spot low-flying drones is limited by the curvature of the earth.
Anti-drone defense systems
One ground-based defense system the U.S. and its allies have built specifically to counter drones at a shorter range is the Coyote. It can intercept drones up to around nine miles away.
A 3-D rendering of a Coyote Block 2 interceptor, which looks like a three-foot tube with small rockets at one end. Two Coyotes cost approximately $253,000 or about seven times that of the Iranian Shahed-136.
The Coyote is significantly cheaper than many of the other ground-based defense systems available to the U.S. and its allies and historically effective at defending important assets. But despite being both effective and cost-efficient, relatively few Coyotes have been procured by the U.S. military in recent years.
When Iran-backed militias launched attacks on U.S. ground troops in the region in 2023 and 2024, there were so few Coyotes available that troops had to shuffle the systems between eight different bases in the region almost daily, according to a report from the Center for a New American Security, a Washington think tank.
Ship-based anti-missile defenses
Many of the longer-range ground-based defense systems the U.S. and its allies can use to combat drones are more expensive, as they are designed to shoot down aircraft and ballistic missiles, not drones. A Navy destroyer’s built-in radar system, for instance, can detect drones from 30 miles away and shoot it down with Standard Missile 2 (SM-2) interceptors. As in the air-based strikes, military protocol stipulates that at least two missiles be fired.
A 3-D rendering of the deck of a Navy destroyer firing an SM-2 missile from a built-in launcher, which looks like a 15-foot missile launching from a grid of openings on the ship’s surface. Two SM-2 missiles cost approximately $4.2 million, about 120 times that of the Iranian Shahed-136.
This misalignment between America’s defense systems and current warfighting tactics started after the Cold War, when the anticipated threats were fewer, faster, higher-end projectiles, not mass drone raids.
Iran often launches multiple Shahed-136 drones at a time, given their low price tag. The drones are also programmed with a destination before launch and can travel roughly 1,500 miles, putting targets all across the Middle East within reach.
“This category of lower-cost precision strike just didn’t exist at the time that most American air defenses were developed,” said Mr. Horowitz.
Ground-based anti-missile defenses
The Army’s standard air-defense system is the Patriot. Typically stationed at a military base, it can shoot down a drone from up to around 27 miles away with PAC-3 Missile Segment Enhancement interceptors. Military protocol stipulates that at least two missiles be fired.
A 3-D rendering of a Patriot launcher loaded with 17-foot PAC-3 MSE missiles, which looks like a tilted shipping container with scaffolding. Two PAC-3 MSE missiles cost approximately $8 million, about 220 times that of the Iranian Shahed-136.
Patriot missile defense system
Air defense training teaches service members to prioritize using longer-range defense systems first to “get as many bites at the apple as you can,” but those are the most expensive, said Stacie Pettyjohn, a senior fellow and director of the defense program at the Center for a New American Security.
But a costly defense can still make economic sense to protect a valuable target, especially those that are difficult to repair or replace, such as the nearly $1.1 billion radar at a military base in Qatar and the $500 million air defense sensor at a base in Jordan that were damaged early in the conflict.
Ground-based guns
Finally, there is what one might call a last resort: a ground-based gun. When a drone is about a mile away or less than a minute from hitting its target, something like the Centurion C-RAM can begin rapidly firing to take down the drone.
A 3-D rendering of a Centurion C-RAM, which looks like a gun mounted to a rotating, cylindrical stand. The gun fires 75 rounds of ammunition per second. Five seconds of firing the gun costs $30,000, slightly less than a single Iranian Shahed-136.
Centurion Counter-Rocket, Artillery and Mortar
Fires 375 rounds of ammunition in 5 seconds
Even though it is fairly cost-effective, the Centurion C-RAM is not the best option because it has such a short range.
Interceptor drones
There’s also what one might call the future of fighting drones: A.I.-powered interceptor drones. Interceptor drones like the Merops Surveyor can theoretically hunt and take down enemy projectiles from a short range.
A 3-D rendering of a Surveyor drone, which looks like a three-foot tube with wings and a tail. The Merops drone costs approximately $30,000, a little less than a single Iranian Shahed-136.
Merops system: Surveyor drone
Eric Schmidt, the former Google chief executive, founded a company to develop the Merops counter-drone system in conjunction with Ukrainian fighters, who have already been combatting Iranian drones in the war with Russia for years.
The U.S. sent thousands of Merops units to the Middle East after the conflict began, but it is unclear whether they have been deployed. The military set up training on the system in the middle of the war, as reported by Business Insider.
Other attempts to lower the cost-per-shot ratio of taking out a drone have failed.
The Pentagon invested over a billion dollars in fiscal year 2024 researching directed energy weapons, or lasers, that would cost only $3 per shot and have a range of 12 miles. Those systems have yet to be used in the field.
Despite the cost imbalance, the real fear for many in the defense community is the depleted stockpile of munitions.
“What scares me is that we will run out of these things,” said Tom Karako, the director of the Missile Defense Project at the Center for Strategic and International Studies in Washington. “Not that we can’t afford them, but that we’ll run out before we can replace them.”
World
Moscow-born gunman dead after Kyiv shooting rampage leaves at least 6 dead, 14 wounded: Zelenskyy
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A Russian gunman was killed by special forces Saturday in Ukraine after opening fire at a supermarket in Kyiv, killing six people and wounding 14 others — including a 12‑year‑old boy.
The 58-year-old shooter long resided in the Donetsk region and was born in Moscow, according to Ukrainian President Volodymyr Zelenskyy and Interior Minister Ihor Klymenko.
He took at least four hostages, killed one of them, and fatally shot four others on the street, Zelenskyy said. Another woman died at a hospital from her injuries.
Graphic video captured by witnesses showed the gunman shooting at a victim within close range on the street. Other bodies were seen lying on the pavement and in courtyards.
The gunman was seen walking with a weapon on the street. (Obtained by Will Stewart)
MANHUNT UNDERWAY AFTER GUNMEN STORM CHICK-FIL-A LEAVING 1 DEAD
Ukranian special forces stormed the convenience store after 40 minutes of failed negotiations, according to Klymenko.
At least fourteen people were wounded in the attack, though officials cautioned the number may rise as people continue to seek medical assistance.
Among the injured is a 12‑year‑old boy and a supermarket security guard, according to Kyiv Mayor Vitali Klitschko.
The gunman was pictured dead in the convenience store. (Obtained by Will Stewart)
NINE DEAD, 13 WOUNDED IN SECOND TURKISH MASS SHOOTING IN TWO DAYS
Zelenskyy said the shooter also set fire to an apartment prior to the attack, though it is unclear if any injuries resulted from the arson.
“My condolences to the families and loved ones of the victims,” Zelenskyy wrote in an X post. “…We wish all the wounded a swift recovery.”
The gunman had previously been prosecuted for criminal offenses, but held a valid weapons permit, according to authorities. Investigators from the National Police and the Security Service of Ukraine are investigating.
The gunman was seen holding and shooting a weapon in the street. (Obtained by Will Stewart)
GUNMAN OPENS FIRE AT HIGH SCHOOL IN TURKEY, WOUNDING AT LEAST 16
Ukraine’s security service labeled the attack an act of terrorism.
“All available information about him and the motives behind his actions is being thoroughly investigated,” Zelenskyy said. “Every detail must be verified.”
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One of the shooter’s neighbors, Hanna Kulyk, 75, described him as an “educated, refined man,” who lived alone and did not socialize often.
“You’d never guess he was some kind of criminal,” Kulyk told The Associated Press.
Top negotiator Mohammad Bagher Ghalibaf says US naval blockade of Iran’s ports is ‘a clumsy and ignorant decision’.
Published On 18 Apr 2026
Iran’s Islamic Revolutionary Guard Corps Navy (IRGC) says the Strait of Hormuz is closed and that any ship that attempts to pass through the waterway will be targeted, a dramatic reversal less than 24 hours after the critical shipping lane was reopened.
In a statement carried by Iran’s Student News Agency, the IRGC navy said on Saturday the strait will be closed until the United States lifts its naval blockade on Iranian vessels and ports. It said the blockade was a violation of the ongoing ceasefire agreement in the US-Israel war on Iran.
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“We warn that no vessel of any kind should move from its anchorage in the Persian Gulf and the Sea of Oman, and approaching the Strait of Hormuz will be considered cooperation with the enemy, and the offending vessel will be targeted,” it said.
Mohammad Bagher Ghalibaf, Iran’s parliament speaker and a senior negotiator in talks between Washington and Tehran on ending the war, said in a television interview that “the Strait of Hormuz is under the control of the Islamic Republic”.
“The Americans have been declaring a blockade for several days now. This is a clumsy and ignorant decision,” he added.
The reassertion of control came just hours after Iran had briefly reopened the strait, in line with a 10-day ceasefire between Israel and Lebanon. Oil prices dropped on global markets after Iranian Foreign Minister Abbas Araghchi said on Friday that the waterway was “completely open for all commercial vessels.”
More than a dozen commercial ships passed through the waterway before the IRGC reversed course.
Iranian gunboats reportedly fired on two commercial ships on Saturday, according to United Kingdom Maritime Trade Operations (UKMTO). India’s Ministry of External Affairs also said that two Indian-flagged ships were involved in a “shooting incident” in the strait.
Some merchant vessels in the region received radio messages from the IRGC Navy, warning that no ships were being allowed through the strait.
US President Donald Trump said Tehran could not blackmail Washington by closing the waterway and warned that he would put an end to the ceasefire if a deal before its expiry on Wednesday is not reached. Trump added that the naval blockade would “remain in full force”.
Iranian Supreme Leader Mojtaba Khamenei, meanwhile, said the navy was ready to inflict “new bitter defeats” on its enemies.
‘Two competing blockades’
Al Jazeera correspondent Zein Basravi said that Iran and the US are back where they were the previous day.
“Less than 24 hours ago, world leaders were praising what they thought was a breakthrough in this conflict, hoping Iran was signalling a confidence-building measure by opening the Strait of Hormuz, potentially leading to a ceasefire deal and a permanent end to the war,” he said.
“As disappointed as people may be, this isn’t entirely surprising. What we’re seeing now is a return to square one,” he added, saying there are now “two competing blockades in place”.
Al Jazeera’s Ali Hashem, reporting from Tehran, said Iran was using the strait to send a message.
“It’s clear that Iran is dealing with a situation in which they are not sure what’s on the table. So the Strait of Hormuz is once again the only space for engagement, even if it’s a negative engagement. And it’s the space where they are sending and conveying messages to the Americans, showing their leverage,” he said.
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