Why Do We Need the Charlie-Gibbs Marine Protected Area?

Far Out in the Ocean

Figure 1. Three-dimensional bathymetric map of the Mid-Atlantic Ridge with the Charlie-Gibbs Fracture Zone in the middle. The ridge itself is the red-orange-yellow area between 1000 and 2500 m depth. Source: Mar-EcoThe Charlie-Gibbs MPA is located in a highly complex section of the Mid-Atlantic Ridge between Iceland and the Azores. It extends from the relatively shallow Reykjanes Ridge in the north (55° N) across the deepest of several deep-sea trenches (fracture zones) to include the deep and dispersed ridge section down to 49° N. Within the boundaries of the Charlie-Gibbs MPA, biodiversity is enhanced due to a latitudinal and longitudinal biogeographic shift, the occurrence of shallow and deep ridge features with associated habitats, a fracture zone which provides for the only east-west deep water faunal exchange and the meeting of subpolar and temperate pelagic fauna in a permanent surface hydrographic front. Due to its size, the Charlie-Gibbs MPA is thought to be representative of that section of the Mid-Atlantic Ridge. Together with a proposed MPA on the Reykjanes Ridge and a designated site north of the Azores it would mirror the range of fauna between Iceland and the Azores.

 

Figure 1. Three-dimensional bathymetric map of the Mid-Atlantic Ridge with the Charlie-Gibbs Fracture Zone in the middle. The ridge itself is the red-orange-yellow area between 1000 and 2500 m depth.
Source: Mar-Eco (click image to enlarge)

 

Why Do We Need a Marine Protected Area?

The Charlie-Gibbs MPA will constitute a representative open ocean and deep-sea part of the envisaged global and regional network of MPAs, illustrating most of the values highlighted by OSPAR, the Convention on Biological Diversity (CBD) and the United Nation's Food and Agriculture Organization (FAO):

  • it is important for declining and threatened species in the North-East Atlantic
  • it is representative of several biogeographic regions
  • it is ecologically significant
  • it hosts a region of particularly high abundance and biomass of fauna
  • it hosts a high proportion of sensitive and vulnerable fauna
  • it has a very high value for science
  • some parts have been impacted by deepwater fishing

General Characteristics of the Area

The Charlie-Gibbs Marine Protected Area (CG-MPA) covers 324,000 km2 of the Mid-Atlantic Ridge between Iceland in the North and the Azores in the South (OSPAR Commission, 2010). It is located in OSPAR Region V, the open Atlantic, in cool temperate and warm temperate waters overlaying the North Atlantic deep sea (Dinter, 2001). The area contains a wide range of benthic and pelagic habitats and communities from the deep sea to a number of relatively shallow peaks and seamounts on the ridge.
 

The Mid-Atlantic Ridge (MAR) profoundly influences the regional water circulation system and separates the deep seas of the eastern and western Atlantic Ocean from pole to pole. Within the OSPAR Maritime Area, the MAR extends from the Lomonosov Ridge in the Arctic Ocean through Iceland to the Azores, and further south. The MAR is a spreading zone where new earth crust is built, leading to a slow separation of continental plates.

 

The MAR is comparable to a mountain chain under water. Like the Alps, the ridge system has deep valleys, canyons and peaks rising up to 3500 m from the seafloor, reaching to 700-800 m below the surface. More than 170 seamounts with summit depths less than 1500 metres were found in this region between 43° and 60°N. Fracture zones, where  geological processes have offset the direct continuation of the ridge by up to 5° longitude, cut deep east-west trenches across the mountain range, providing the only exchange routes for deep-sea fauna. The Charlie-Gibbs Fracture Zone is the northernmost and deepest of these zones.
Almost coinciding with the location of the Charlie-Gibbs Fracture Zone is the seasonally shifting location of a permanent hydrographic front where warm, saline North Atlantic water meets cold, less saline water from the Labrador and Irminger Seas. The frontal zone is marked by an elevated abundance and diversity of many taxa from plankton to whales, as well as higher biological production and biomass in the pelagial and benthal. Some deep-sea sharks depend on such zones of improved feeding conditions.

Biogeographic Divide

Figure 2. North-South transition of the dominant commercially relevant fish species on the MAR Redfish, roundnose grenadier, alfonsino. Shibanov et al., 2002The Charlie-Gibbs MPA includes three faunistically different regions: the areas north and south of the subpolar front, and the region of the subpolar front itself. The mountain range separates the benthic deep-sea fauna of the northwest and northeast Atlantic, whereas the subpolar front separates the northern and southern fauna latitudinally. For example, north of the subpolar front, cold-water fish species like Greenland halibut and giant redfish are found, whereras to the south, more temperate roundnose grenadiers and alfonsinos dominate among the fish.


Figure 2. North-South transition of the dominant commercially relevant fish species on the MAR: redfish, roundnose grenadier, alfonsino. Source: Shibanov et al., 2002 (click image to enlarge)

 

Particular Features

Like mountain ranges on land, the MAR provides a range of niches and habitats across a large range of depth, and on soft as well as hard substrates. The relatively large areas of rocky outcrops, in particular those in shallower waters, provide important settlement areas for benthic fauna like hexactinellid sponges and scleractinian corals,  connecting different regions of the North Atlantic. The so-called seamount fishes like redfish, roundnose grenadiers, or orange roughy seasonally aggregrate over the steep slopes of the shallower ridge peaks. Sperm and sei whales have been observed in the vicinity of seamounts.

Species Inventory

The number of taxa identified from the area is impressive, even if only considering some trophic levels only: 40 cold-water coral taxa, 53 species of cephalopods, 80 species of demersal fish--including 44 species of deepwater sharks, 22 species of seabirds, and 13 cetacean species.

Vulnerable Habitats and Species

Vulnerable species and habitat-forming groups such as corals cannot quickly recover from losses in density or extent. Such taxa most often grow slowly but to relatively large maximum size, mature later than humans and grow at least as old as a human. Like humans they have few offspring at irregular intervals. However, the lifecycle of most species remains fairly unknown. Deepwater species such as orange roughy (H. atlanticus) or deepwater sharks are considered vulnerable, as are biogenic habitats like those formed by cold-water corals and sponges.

Species and Habitats Under Threat and Decline in the OSPAR Area

The Charlie-Gibbs MPA will also provide protection for a range of other species and habitats which are under threat or decline in the OSPAR area (OSPAR Commission, 2008).
In particular, these include seamount habitats, Lophelia pertusa reefs, coral gardens, deep-sea sponge aggregations, several deepwater shark species, orange roughy, leatherback turtles, and blue whales. Not listed by OSPAR as under threat and/or decline but of concern for the conservation of the area are several benthic habitat types and their associated communities, deepwater and pelagic ecosystems and more widely cetaceans, deepwater sharks, oceanic seabirds and the fishes associated with the polar front.

Past and Current Threats

Despite its remoteness, there has been intense deepwater fishing in the MAR since the 1970s. The fishing pressure decreased considerably when the Soviet Union ceased to exist. Currently it is reduced to almost zero due to stricter regulation, and to low profit margins on over-exploited stocks fished at increasing cost. However, recent exploration in ridge areas outside the current closures signals a continued interest should the fishstocks recover.

 

Bibliography

 

WWF Sources

 

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