Red snapper

A large amount of New Zealand’s seagrass have been killed by sediments released from land development. The seagrass bed at Whangarei Harbour has for instance been reduced from 14 sq km in the 1960s to virtually non-existant today. And sedimentation this is not a new problem – between 1959 and 1966 Tauranga Harbour lost 90 per cent of its seagrass.

Researchers at New Zealands’s National Institute of Water & Atmospheric Research are now fitting the floor of the Whangapoua Estuary with plastic seagrass in an attempt to show how New Zealand’s fish stocks could be boosted by restoring the seagrass habitats. The “seagrass” consists of plastic fronds attached to wire frames, and the length of the fronds varies from 5 cm to 30 cm.

“We made them with tantalising long blades of artificial grass, the things fish really go for,” says NIWA fisheries ecologist Dr Mark Morrison. “What we found, initially, is that fish are really looking for shelter and seagrasses provide good protection to fish.”

The largest density of fish could be found where the density of seagrass was also at its largest.

Fish is now being tagged to make it possible for the researchers to track both growth rate and survival rate.

Dr Parker, from James Cook University’s School of Veterinary and Biomedical Sciences, and collaborator Professor Rocky de Nys, from JCU’s School of Marine and Tropical Biology, have just received a $7,000 Collaboration Across Boundaries grant to prove their theory that feeding seaweed to cow will improve their digestion and make them produce less methane.

Just like carbon dioxide, methane is a so called green-house gas and the world’s cattle population accounts for up to 20% of methane emissions from human-related activities. Global warming is suspected to be one of several factors harming our tropical reefs worldwide and finding ways of reducing the amount of methane released into the air is therefore highly interesting.

Dr Parker and Professor Rocky de Nys will now test their theory on herd of cattle living at the University’s Townsville campus.

“Orkney sheep are ruminants that live off seaweed and they do very well on such a diet; so the obvious question is, why can’t cows?” said Dr Parker.

“I like to call it the reef and beef project because it has far reaching implications that come full circle:starting with seaweed, taking in the beef and aquaculture industries, and extending back out to the sea to help conserve the Great Barrier Reef.”

The invasive kelp Undaria pinnatifida is has now spread from Los Angeles to San Francisco Bay, despite eradication efforts.

Earlier, the northward spread of this sea weed – which can grow an inch a day and forms dense underwater forests – was believed to have been stopped at Monterey Bay, but this assumption turned out to be wrong when a biologist at the Smithsonian Environmental Research Center happened to notice a six-foot long piece of kelp attached to a boat in a yacht harbor in San Francisco Bay.

“I was walking in San Francisco Marina, and that’s when I saw the kelp attached to a boat,” said Chela Zabin, biologist at the Smithsonian Environmental Research Center in Tiburon, California. “It was six-foot long, and there is nothing here in the bay that gets to that size. I didn’t want to believe what it was, it’s depressing.”

Further investigation showed U. pinnatifida clinging not only to boat hulls in the marina but to docks and pier pilings as well.

U. pinnatifida was discovered in Los Angeles Harbour in 2000 and within a year reports of its presence had arrived from Catalina Island and Monterey Bay. A federal eradication program was put in place, but the funding dried up last year. Since then, volunteer divers have been the only ones combating the kelp.

Five quick facts about Undaria pinnatifida

• Undaria pinnatifida is a fast growing kelp native to the waters of Japan, China and South and North Korea.

• Within its native range it is an appreciate source of food and if you’ve ever tasted miso soup, this is what you were eating. The Japanese name for this species is wakame.

• U. pinnatifida has managed to establish itself in many different regions outside its native range, such as the Atlantic coast of Europe, the Mediterranean Sea, and the Argentinean coast. By attaching itself to vessel hulls it can hitchhike across the globe in search of new suitable habitats. This kelp can also enter ecosystems via imported oysters, and some people deliberately or accidently introduce U. pinnatifida to local ecosystems by cultivating it for cooking purposes.

• When U. pinnatifida spread to ecosystems not used to its presence, it can grow uncontrolled and prevent native kelp species from getting any sunlight. This can disturb the entire ecosystem.

• U. pinnatifida has been nominated to the list “100 worst invasive species in the world”.