Visitors to the shores of Eilat in the northern Gulf of Aqaba, Red Sea, during March and April in recent years have witnessed an unusual sight—stretches of shoreline turning pink.
Upon closer inspection, millions of tiny pink creatures with large eyes were found covering the sand.
A new study led by Prof. Tamar Guy-Haim from Israel Oceanographic and Limnological Research (IOLR) and Ben-Gurion University, in collaboration with Dr. Bracha Farstey from the Interuniversity Institute for Marine Sciences in Eilat, has revealed that these creatures are a type of planktonic crustacean called amphipods.
Their research, published in Ecology and Evolution, explains this mysterious event.
Why Are These Creatures Pink?
The pink color in some amphipods comes from carotenoid pigments, which they obtain through their diet.
The researchers used a combination of physical identification and genetic testing to classify the amphipods and studied environmental conditions to understand why they appear in such large numbers each year during these months.
What Causes Their Mass Stranding?
Prof. Guy-Haim and her team considered several possibilities. Some species of amphipods have a unique reproductive strategy called semelparity, where they reproduce only once before dying.
However, the researchers found an equal number of males and females, as well as amphipods of various sizes, ruling out semelparity as the cause.
They also investigated climate change, particularly marine heatwaves, which have caused mass deaths of marine life in the past. For example, in 2017, a sudden rise of more than 4°C in sea temperatures killed many coral reef fish in Eilat. However, temperature records did not show any unusual heat events before or during the amphipod strandings.
Another potential explanation was disease or parasite infections, as environmental stress can make marine animals more vulnerable. But the researchers found no evidence of infections in the amphipods either.
A cyclical natural event?
While searching old scientific records, the team found a report from 1977 describing a similar amphipod mass mortality event in March in the Gulf of Aqaba. This suggests that the phenomenon might be part of a natural seasonal cycle rather than an unusual occurrence.
The most likely explanation involves ocean currents. In the Gulf of Aqaba, powerful circular currents called cyclonic eddies form between November and April. These currents can bring nutrient-rich deep water to the surface or push surface water downward. The researchers hypothesize that amphipods were caught in one of these eddies and carried to shore, similar to an event recorded in Hawaii involving the same amphipod species.
Amphipods are a key part of marine food chains, serving as food for fish, seabirds, and even whales. Understanding their movements and population cycles can help scientists learn more about the ocean’s complex ecosystem.
This discovery provides important insights into how ocean currents shape marine life and highlights the need for further research into similar natural events worldwide.
