The research was conducted by Mey-Tal Gewing, of TAU's School of Zoology and led by Dr. Noa Shenkar, also of TAU's Department of Zoology and of The Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies. It was published in Marine Pollution Bulletin.

Key findings

  • 45 marine vessels were surveyed for presence of non-indigenous ascidians (NIA).
  • NIA were found on every second monitored vessel.
  • Military vessels and niche areas exhibited the highest NIA abundance and richness.
  • Marine vessels monitoring can serve as an early detection tool for NIA.

Invasive ascidians  are nuisance organisms that contribute to biodiversity loss, ecosystem degradation and impairment of ecosystem services around the world, posing a significant global threat.

"These organisms are well known in the US and Canada," Dr. Shenkar said. "In Israel, they are passing through the Suez Canal, latching onto ropes and the bottom of the ship. They're filter feeders, so they cover and clog every surface they latch onto, creating a lot of drag for the ship and damaging marine biodiversity in their new environments. They're a major threat to our coasts and are very costly to ship owners."

The researchers inspected 45 vessels, both commercial and military, discovering that the military vessels, which undergo maintenance every six months, were actually more prone to ascidian invasion than commercial ships, which are cleaned every two years by law. According to Dr. Shenkar, this happens because maintenance for commercial ships is much more thorough, including repainting and hosing down every nook and cranny of the vessel.

According to Science Daily, the study also found that high seawater temperature is a relevant factor to ascidian invasion.

In view of these, Dr. Shenkar recommended operators to conduct maintenance before the warm season begins and that all areas of the boats to be checked. They are also advised to use silicon-based paint, to which larvae can't attach, to cover areas such as the seachest.

In the course of their research, the scientists also discovered a Caribbean species new to the region. A discovery of a new introduced species during the surveys suggests that the monitoring of marine vessels can serve as an effective tool for the early detection of NIA.

The researchers are currently working with policymakers in Israel and the EU to tailor environmental protection measures that would ward off non-indigenous ascidians.