Cashes Ledge is a large rise in the seafloor located 80 miles east of Cape Ann, Massachusetts. Here, a rocky pinnacle called Ammen Rock reaches within 40 feet of the surface. The dynamic oceanography of the location and the variety of habitats provided by rocky ledges, sloping walls, rubble piles, and soft bottom makes for a uniquely diverse and productive ecosystem.
We have been working to describe the ecological and environmental mechanisms that support and sustain this biodiversity hotspot of the Northeast Atlantic. In May and June 2014, we spent two weeks diving both at Cashes Ledge and at sites near the coast in an effort to compare nearshore and offshore marine habitats. Sponsored by the Conservation Law Foundation (http://www.clf.org/cashes-ledge/), the goal of these dives is to provide both scientific evidence and visual imagery to show why Cashes Ledge is the gem of the Gulf of Maine, and worthy of special protections.
We have been working to describe the ecological and environmental mechanisms that support and sustain this biodiversity hotspot of the Northeast Atlantic. In May and June 2014, we spent two weeks diving both at Cashes Ledge and at sites near the coast in an effort to compare nearshore and offshore marine habitats. Sponsored by the Conservation Law Foundation (http://www.clf.org/cashes-ledge/), the goal of these dives is to provide both scientific evidence and visual imagery to show why Cashes Ledge is the gem of the Gulf of Maine, and worthy of special protections.
What makes Cashes Ledge so special? For one thing, it is the largest and most productive kelp forest we know of in the Gulf of Maine. Kelp is a general term referring to brown seaweeds of the order Laminariales. Kelp forests on Cashes are primarily composed of Saccharina longicruris, which reaches lengths of 15 feet. This 3-dimensional complexity provides a major habitat for fishes such as Cod and Pollock, making the ecosystem more productive than comparative sites nearer to shore.
Professor Jon Witman and diver Elizabeth Kintzing from UNH sort kelp from Ammen Rock onboard the Tioga. We counted as many as 130 fronds for more than 5 kilograms of biomass in a single square meter!
One of the iconic species of the Gulf of Maine, the Atlantic Cod (Gadus morhua), has found a special refuge at Cashes Ledge. Whereas no cod were observed during our dives at nearshore sites such as the Isles of Shoals, we saw several at Ammen Rock, along with dense schools of Cunner (Tautogolabrus adspersus) and Pollock (Pollachius virens).
Cod have long been a staple food and source of cultural heritage for New England. Colonists in the 1600s described lowering a basket into the water off of a dock and bringing it back up full of cod. An easy fish to catch and preserve by salting (in an era before refrigeration), cod was massively exploited for centuries until a major fishery collapse in the 1990s. Today, places such as Cashes Ledge may provide an essential sanctuary and breeding ground for the replenishment of nearby depleted stocks.
But what does a cod look like? Coming face to face with one underwater is a special feeling, as these charismatic fish are curious and approachable. Here we see a video from Ammen Rock showing two cod interested in the stationary camera. The distinct white line running down the side of the fish is called the "lateral line", which is a row of special sensory epithelial cells that serve to detect movement and vibration. The fleshy appendage sticking off of the bottom of the fish's chin is called a "barbel", and is also a special sensory organ that is used to find food in murky waters and soft-bottom habitats.
Cod have long been a staple food and source of cultural heritage for New England. Colonists in the 1600s described lowering a basket into the water off of a dock and bringing it back up full of cod. An easy fish to catch and preserve by salting (in an era before refrigeration), cod was massively exploited for centuries until a major fishery collapse in the 1990s. Today, places such as Cashes Ledge may provide an essential sanctuary and breeding ground for the replenishment of nearby depleted stocks.
But what does a cod look like? Coming face to face with one underwater is a special feeling, as these charismatic fish are curious and approachable. Here we see a video from Ammen Rock showing two cod interested in the stationary camera. The distinct white line running down the side of the fish is called the "lateral line", which is a row of special sensory epithelial cells that serve to detect movement and vibration. The fleshy appendage sticking off of the bottom of the fish's chin is called a "barbel", and is also a special sensory organ that is used to find food in murky waters and soft-bottom habitats.
