Ecosystems

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.

The reef appears to sprawl across more than 3,600 square miles of ocean floor at the edge of the South American continental shelf, from the southern tip of French Guiana to Brazil’s Maranhão State.

Extensive reef system discovered at the Amazon River mouth

The existence of the reef have come as big surprise because many of the world’s great rivers produce major gaps in reef systems where no corals grow. There was little previous evidence because corals mostly thrive in clear, sunlit, salt water, and the equatorial waters near the mouth of the Amazon are some of the muddiest in the world, with vast quantities of sediment washed thousands of miles down the river and swept hundreds of miles out to sea.

Reef architecture is built by the accretion of calcium carbonate, called calcification, which becomes increasingly difficult as acid concentrations increase
Reef architecture is built by the accretion of calcium carbonate, called calcification, which becomes increasingly difficult as acid concentrations increase

Ocean acidification already slowing coral reef growth

Coral reefs are particularly vulnerable to the ocean acidification process, because reef architecture is built by the accretion of calcium carbonate, called calcification, which becomes increasingly difficult as acid concentrations increase and the surrounding water's pH decreases.

  Salt marsh, Sept-Îles, Quebec, Canada
Salt marsh, Sept-Îles, Quebec, Canada

Hurricanes have minimal impact on salt marshes

New research suggests that major hurricanes, though devastating to humans, have a minimal impact on salt marshes. The Boston University study reveals coastal ecosystems are more at risk of erosion by waves from moderate storms than from full-fledged tropical storms. In eight different marshes studied in the United States, Italy and Australia, extreme storm events accounted for less than one per cent of erosion.

The comeback kid? Schools of plaice in the North Sea and Skagerrak are the largest ever recorded.

Resurgence of North Sea fish stocks

Many years of restraint and restrictive fishing quotas seem to finally have paid off. Within a decade the stocks of spawning cod have almost doubled

Though levels of cod in the North Sea are not yet what they were pre-crisis, a remarkable recovery is well under way and advancing. Along with cod and plaice stocks of herring, haddock, hake, Norway lobster, common dab and witch (Torbay sole) are also improving .

A free-standing red mangrove tree growing in shallow water in the Everglades National Park

Mangroves protect coral from climate change

Coral reefs make up some of the most biologically diverse habitats on Earth and face many threats such as coastal pollution, dredging and disease. However, some of their most widespread threats involve warming ocean temperatures, solar radiation and increased ocean acidification. It is from these threats that corals are finding refuge under the red mangroves.

The relative abundance of sharks was significantly higher in non-fished sites

Healthy reefs have more sharks

The present study examined shark distribution patterns, species-habitat associations, and marine reserve use with baited remote underwater video stations (BRUVS) along the entire Great Barrier Reef Marine Park (GBRMP) over a ten-year period.

Overall, researchers recorded 21 different shark species. The relative abundance of sharks was significantly higher in non-fished sites in the GBR Marine Park no-fishing zones relative to fished sites.