Jellyfish swell in size as season hits its peak
As Israel’s yearly jellyfish influx approaches its apex, researchers from Haifa University have found that the ones that reach Israel’s shores seem to be getting larger and more diverse, according to the University of Haifa’s Leon
H. Charney School of Marine Sciences.
Researchers from the school have been studying the ecology and life cycle of jellyfish along Israel’s coast for years. This year, as a huge swarm of jellyfish appeared off Haifa’s coast, the researchers took the opportunity to get a closer look at Israel’s all-too-familiar summer marine animals and were surprised when they noticed their abnormal size.
“Overall, this is the summer bloom of jellyfish that we anticipate,” said the University of Haifa’s Prof. Dror Angel. “But there’s a slight difference in the size of jellyfish. On average, they’re bigger this year than in other years.”
Different explanations that could shed some light on the phenomenon were suggested, including the decrease in human presence along the country’s shores that is a direct result of the coronavirus pandemic. However, most researchers involved with the study agreed that this possibility was unlikely.
Instead, the reasons are most likely environmental ones rather than being manmade, they said.
“I don’t think the coronavirus has anything to do with the jellyfish,” Angel said. “I think nature is the bigger player. We’re looking at cues like changes in temperature, as these probably play a role in determining when jellyfish appear. Rainy winters or more arid winters could determine the size of the bloom the following summer.
“We haven’t identified human-driven factors like pollution, which could also be affecting the blooms. At the moment, we think natural phenomena have more of an impact than human effects.”
The School of Marine Sciences, conveniently located on the doorstep of the Mediterranean Sea, pursues maritime research with practical
applications.
Jellyfish affect thousands of Israelis every year. Most people consider them to be nothing more than a nuisance during their attempts to escape the hot weather and enjoy the cool Mediterranean breeze.
That is not the case for Angel, who said his team is “trying to understand the ecology of the various jellyfish in our coastal waters: When do the blooms appear; why are they bigger or smaller in some years and so on.” They are “also looking for missing evidence in the life cycle of the nomadic jellyfish: Where are certain life stages found; what eats the jellyfish and what do the jellyfish eat; how they interact with the marine system,” he said.
But jellyfish actually have the potential to address wider environmental issues, Angel said, adding that his researchers “are exploring the use of jellyfish as a means to reduce microplastic pollution in the ocean.”
“One of the outstanding observations over the past decade is that we keep finding what we consider new jellyfish in our coastal waters,” he said. “Different, intriguing species keep appearing. Although we consider them new, it’s possible that they’ve been around and we just didn’t see them until they became more abundant. It seems that the more you look, the more you see.” •