Ecosystems

River Treasures: Freshwater Biodiversity in Italy

The trench live in freshwater lakes and streams. Photo by Marco Colombo.

When considering underwater photography, we usually think about images of wonderful coral reefs, colourful fish, clear waters and undersea landscapes. In fact, 70 percent of our planet is covered by water on its surface, and, even though 97 percent of this is saltwater, the remaining three percent is freshwater in rivers, streams, lakes, ponds, marshes and groundwater.

Some fish 'farm' their food

Working on Palmyra atoll, around 1,000 miles south of Hawaii, a team of researchers from the University of California Santa Barbara became aware of the fish's farming habit when they noticed many bite marks in specific areas of algae growing on dead coral.

They followed these patches through time and found parrotfish were feeding heavily in each patch for a short period of time. Then, the fish would allow that exact location to recover before returning to harvest the algae again.

Removal of large shark species by fishers may lead to explosions in smaller shark species

Sharks influence fish communities at coral reefs

The research team from University of Western Australia arrived at this conclusion after a study involving two coral reefs. At one of the reefs (Scott Reef), shark hunters had been legally permitted to hunt sharks while the other reef (Rowley Shoals) was situated in a marine protected area.

Symbiosis

Candy-striped Shrimps with Crimson Anemone

Marine ecosystems are complex and dynamic places in which species interact in a myriad of ways: they both compete and cooperate for protection, shelter, food and various other resources. For certain species, these interactions may have negative effects (such as competition or predation) or positive ones (in the form of symbiotic relationships).

Blue mussels, edulis mytilus, are effective filter feeders

Blue mussel beds can clean fjords and bays

A project conducted by researchers from Denmark's Technical University showed that 18 hectares of blue mussels in Skive Fjord reduced the levels of algae low enough to prevent oxygen depletion.

The main issue with fertilization of coastal waters causing algae bloom stems from the massive amounts of dead algae sinking to the bottom in thick layers. As they rot, they consume and deplete oxygen, choking huge swathes of the seabed, leading to widespread bottom death. This is a big issue along coasts of agricultural areas.

Common Lionfish

Proposed bill to ban lionfish sales in Florida

Tallahassee lawmakers are joining spear-wielding divers in an attempt to control Florida’s ever-increasing lionfish numbers. If passed, the two proposed bills would halt the public’s ability to purchase lionfish for aquariums and raising them for sale would become a level two felony.

All of the details of the bill have not been decided. I’m saying let’s get rid of them. Put an end to lionfish in aquariums.

—Sen. Greg Ever

Beyond the Muck

Muck diving is a term used quite frequently these days that can be applied to either a dive site, a type of diving or even an entire region like Lembeh Strait in Indonesia or Anilao in the Philippines.

These areas of the Indo-Pacific have consistently ranked amongst the highest in terms of high coral counts, reef fish and of course the high impact Holy Grail of critters.