A Paramuricea coral in Nygren Canyon, 165 nautical miles southeast of Cape Cod, Massachusetts. Image via NOAA/Okeanos Explorer
A Paramuricea coral in Nygren Canyon, 165 nautical miles southeast of Cape Cod, Massachusetts. Image via NOAA/Okeanos Explorer

New England’s Corals

When most of us think of coral, we picture a scene not unlike that found in Pixar’s Finding Nemo: a vast multicolored reef in the warm shallow waters of the tropics, inhabited by a multitude of equally colorful fish. But did you know that many intricate and colorful species of coral can be found right here in our own New England waters? Growing along the ridges of underwater canyons and seamounts off the Atlantic coast, the New England version of a tropical reef plays host to our own aquatic flora and fauna, more suited to the chilly waters of the northwest Atlantic.

Though they resemble undersea plants, corals are in fact colonies of tiny, soft-bodied invertebrates whose secreted exoskeletons form, over time, the large and intricate structures that we recognize as coral. In the warm waters of the tropics, groups of these exoskeletoned colonies form extensive reefs in the clear, shallow waters close to the shore.

Though snorkelers may appreciate the clear waters of the tropics, the water is so clear in these areas because it contains few nutrients or plankton. Very little mixing of the water column occurs in these uniformly warm waters, so nutrients remain trapped on the bottom of the sea, preventing the multiplication of plankton, and leaving the water empty of food. As a result, tropical corals get their nutrients through a symbiotic relationship with photosynthetic algae, which grows inside the coral and lends it energy from the sun.  Large animals like whales, however, are unable to sustain themselves by hosting algae. Instead, whales like humpbacks and right whales breed in tropical waters but return to New England to feed in the summer. The constantly mixing warm and cold waters of New England bring nutrients to the surface, encouraging plankton growth, and are thus a veritable soup of life. New England corals enjoy this soup just as much as the whales do, and most of them filter feed instead of relying on algae to do the work for them.

A striking purple coral, Clavularia sp., seen in Nygren Canyon. Image via NOAA/Okeanos Explorer

A striking purple coral, Clavularia sp., seen in Nygren Canyon. Image via NOAA/Okeanos Explorer

New England corals live not in the near-shore shallows but along underwater canyons and seamounts. Last summer, NOAA’s Okeanos mission documented some of the wide array of marine life in the Northeast’s canyons, including Oceanographer Canyon, a deep underwater channel that cuts into the southern edge of Georges Bank. You can see images and video from the mission here. The seamounts are part of the New England Seamount Chain and often rise to within 100 feet of the ocean surface, ensuring a rich habitat for undersea creatures due to the high concentration of particulates in the water and the nearness of sunlight.

Unfortunately, cold water corals grow slowly and are very susceptible to the effects of trawling, which is why Fishery Management Councils along the east coast have begun to take action to protect areas like canyons and seamounts with rich deep-sea coral populations.

New England’s corals are surrounded by towering kelp forests, fish and mammals of all kinds, and even sea turtles. So if you’ve ever wanted to dive the Great Barrier Reef, but balked at the idea of that plane ticket to Australia, consider exploring the underwater scenery right in our own backyard!

The kelp forest at Cashes Ledge not only provides excellent habitat for marine life; it also serves as a carbon sink.
The kelp forest at Cashes Ledge not only provides excellent habitat for marine life; it also serves as a carbon sink.

Ocean Plants Part 3: Kelp and Climate

Categories: Guest Posters

Many NEOO readers may have come across a description of the relationship between sea otters, sea urchins, and kelp in a biology textbook. A quick recap: sea otters prey on sea urchins, which live in kelp beds and which, in turn, prey on the kelp itself. Sea otter predation, then, protects kelp from predation and allows kelp forests to flourish. Fewer of us are likely to have heard of the Atlantic wolffish, but this snaggle-toothed New England native plays the same role here that the sea otter does in the Pacific: keeping the urchin population down and the kelp population up. Of course, this is good news for kelp, but is it good news for us as well?

The answer is a resounding yes. Kelp provides essential habitat for countless marine species, including commercially important fish. Furthermore, scientific evidence suggests that kelp forests, like their terrestrial equivalents, play an important role in carbon sequestration.

Plants take in and store CO2 as part of the process of photosynthesis. Some of the carbon stored in plants is soon released when the plant decomposes, but some is sequestered in carbon sinks. Forests, swamps, and especially the ocean are all important carbon sinks. Kelp, boasting both a high uptake of atmospheric CO2 and an ocean floor habitat, is a particularly important player in carbon sequestration, and this role is becoming even more important in the face of rising atmospheric carbon dioxide levels and anthropogenic climate change.

New England is home to abundant and diverse kelp forests, notably at Cashes Ledge, where forests of towering laminarian and perforated shotgun kelp grow thickly on the undersea mountain slopes, sheltering abundant fauna including whales, seals, sharks, and commercially important fish such as the Atlantic cod. Detritus from this kelp forest tumbles off the ledge into the neighboring basin, where these nutrients are recycled back into the ecosystem and fuel incredible productivity. Kelp forests like the one at Cashes Ledge may be a critical component of our oceans’ ability to mitigate and adapt to climate change and ocean acidification caused by rising atmospheric carbon dioxide.

Urchins have taken over this kelp bed off Tasmania. Image via NASA.

Urchins have taken over this kelp bed off Tasmania. Image via NASA.

The loss of an apex predator such as the Atlantic wolffish, and a subsequent increase in herbivores (urchins, in this case), leading to a decrease in carbon sequestering plants such as kelp is a well-known effect called a trophic cascade. We can speed such trophic cascades along, in this case either by reducing Atlantic wolfish populations through bycatch and habitat destruction, or by skipping this step altogether and decimating kelp forests through destructive fishing practices such as bottom trawling. Unfortunately, we’ve done just that—Atlantic wolffish are severely depleted, and the kelp forest at Cashes Ledge is threatened by a New England Fishery Management Council proposal that would reopen 75 percent of the area surrounding the kelp forest to commercial fishing (this area has been protected since 2002).

The news that apex predators such as the Atlantic wolfish can help preserve healthy populations of kelp, and that kelp in particular is a highly efficient carbon sequestering plant, tells us two things. First, while the Atlantic wolffish alone may not have much impact on overall climate change mitigation, protecting important predators like the wolffish will build resilience for our ecosystems in more ways than we can count. Second, we New Englanders should support habitat protection and responsible fishing practices that allow our kelp forests to continue flourishing. In doing so, we will promote carbon sequestration and provide habitat for countless fish—including the Atlantic wolffish, that friend of the kelp. After all, in the end, all ecosystems are cyclical.

The edge of an eelgrass bed on sandy bottom. Image via NOAA.
The edge of an eelgrass bed on sandy bottom. Image via NOAA.

Ocean Plants Part 2: Eelgrass

Categories: Guest Posters

Marine plants are the unsung heroes of ocean habitats, providing food, shelter, and substrate to the varied and wonderful animals we love to watch, photograph, or hook on the end of a line. One such plant, eelgrass, or Zostera marina, grows on sandy substrates or in estuaries along the coast and in the sounds of New England. Growing together in long green ribbons, a bed of eelgrass resembles an underwater meadow, swaying in the current.

Eelgrass serves a greater purpose than its beauty, however. Eelgrass beds aid sediment deposition and stabilize the substrate, preventing erosion. They also serve as a home and nursery for both micro-invertebrates and economically important fish and shellfish; a recent NOAA report on the importance of shallow water bottom habitat identified eelgrass as important habitat for juvenile cod, pollock, flounder, and hake, among other species. Eelgrass is also a major food source for several species of marine birds and waterfowl, including brants, redheads, widgeons, black ducks, and Canada geese, and for the endangered green sea turtle.

 

Eelgrass provides essential habitat for numerous fish species. Image via NOAA.

Eelgrass provides essential habitat for numerous fish species. Image via NOAA.

 

Although eelgrass is found throughout the Northern Hemisphere, this essential marine plant is in danger of disappearing from much of its habitat. Several factors are contributing to the decline of eelgrass. Pollution from sewage and fertilizers is a major culprit—it creates an excess of nitrogen in the water, causing algal blooms that block sunlight from reaching the eelgrass and preventing its photosynthesis. Invasive green crabs also harm eelgrass beds by dislodging and shredding stalks of grass as they dig for softshell clams, and green crab populations are growing rapidly in New England. Shellfish rakes, dredges, and boat anchors also destroy eelgrass. In the future, eelgrass faces increased stress from rising ocean temperatures and water levels.

As a result, eelgrass is disappearing rapidly from many of the places it used to thrive, in turn endangering the myriad species that rely on eelgrass for food and shelter, and leading to sediment pollution due to the loss of this important anchor for the marine substrate. Narragansett Bay is one example—once filled with eelgrass, today it has lost 90% of its eelgrass beds.

Yet all hope may not be lost. Since 2001, volunteers and divers working through Save the Bay have participated in eelgrass transplanting efforts. Eelgrass is harvested from healthy beds in the southern end of Narragansett Bay, sorted, and then hand planted by divers, who attach shoots of eelgrass to bamboo skewers and secure the sewers in the substrate. While some of the transplanted beds have failed, others have flourished and spread.

Similar restoration projects are underway in other locations, including Boston Harbor. Efforts to map the current and historical distribution of eelgrass beds are also ongoing in several states and will provide a valuable baseline for future restoration and conservation.

If efforts to mitigate the stresses on eelgrass and restore its original range continue, there is hope for this marine hero—and the abundance of life it supports—to thrive once more.

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Video: Take a 5-Minute Dive on Cashes Ledge

Categories: Cashes Ledge

If only everyone could see and experience the wonder of Cashes Ledge for themselves, we know they would feel as passionate about protecting it as we do. That’s why we’re excited to share with you this new video, filmed with our partner, National Geographic photographer Brian Skerry, Brown University Biologist Jon Witman, and local fishermen. We hope you’ll agree that this video, which features stunning new footage by underwater videographer Evan Kovacs, brings Cashes Ledge to life in a whole new way.

Cashes Ledge is unlike anyplace you’ll find on land or sea – one of the most dynamic hotspots of biodiversity in New England and the entire North Atlantic. But it’s in danger. Cashes Ledge has been protected from the most harmful fishing practices for more than 10 years. But this amazing preserve for fish and ocean wildlife may be just a few months away from having its protected status revoked.

We need your help to make sure that doesn’t happen. You can make a difference for Cashes in just two easy steps:

First, if you haven’t already, please sign our petition to NOAA today, asking them to protect Cashes Ledge.

And second, share this video far and wide with your friends, colleagues, and networks, and ask them to sign our petition and support our work. Because we need many more passionate people like you to take action, today, to protect this remarkable marine refuge.

It’s going to take all of us raising our voices loudly and clearly to protect Cashes Ledge. Thank you for your commitment and for being part of the New England Ocean Odyssey community.

Great white shark off the coast of Chatham this summer.
Great white shark off the coast of Chatham this summer.

White Sharks Get Top Billing at Chatham Benefit Lecture

Categories: Cashes Ledge | Guest Posters

Hypnotic, elusive, and highly charismatic…. Even at a benefit lecture by a world-renowned photographer and a media-savvy scientist, undoubtedly the great white shark was the star.

Everybody wants to know about this A-lister among fish that makes its seasonal vacation home just off New England’s coasts. So like a feeding frenzy of fans, a sold-out, starstruck crowd packed the Chatham Bars Inn for a joint presentation by acclaimed National Geographic photojournalist and New England Ocean Odyssey collaborator Brian Skerry, and Greg Skomal, senior fisheries expert for Massachusetts Division of Marine Fisheries and director of the Massachusetts Shark Research Program. The lecture was a benefit for the Atlantic White Shark Conservancy.

Skerry opened the evening with “Ocean Soul,” the luminously pictorial, ever-evolving documentation of his travels covering marine wildlife all over the globe. He used a photograph of a baby shark in a mangrove nursery to begin a narration of oceanic habitat in Bimini, where ecosystems of reefs, seagrass beds, and mangrove stands interconnect. “Animals flow between all of these,” he pointed out. Skerry emphasized the absolute interdependence of life in marine habitats: “Every animal plays a role,” he said. “Everything matters.”

That interdependence, of course, includes sharks. Skerry’s global perspective set the stage for Skomal’s thrilling regional focus on sharks in New England’s coastal waters. For of the distinct great white shark populations all over the world – in the northeast and northwest Pacific, around the coast of South Africa, and the coasts of Australia and New Zealand – there is one population of great whites that loves Cape Cod. Teeming grey seal populations due to climatic shifts have over the past decade made the Cape a hot vacation spot for this celebrity predatory jet set.

The frequency and predictability of shark visits to the Cape – one shark nicknamed “Julia” returns on almost the exact same date every year – give researchers the rare advantage of access to these animals.

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Above: Dr. Greg Skomal and his team tracking and tagging great white sharks near Chatham.

Aerial spotters help Skomal and his team locate the sharks. Once a shark is spotted, the challenge of tagging begins, with a biologist balancing on the pulpit of a boat to lance the fish’s dorsal fin with an electronic tag via an intramuscular dart. Buoys and receivers on the ocean then create transects that collect data about sharks in the area.

New technology has given researchers more access to sharks, through acoustic tags, pop-up satellite tags, and AUVs (i.e., drones) – autonomous underwater vehicles that send back revealing videos of shark behaviors.

“We know that they are dynamic and highly migratory, with complex migratory patterns,” said Skomal. “They are warm-bodied, so they can go anyplace they want. They are far more remarkable than we had ever imagined.”

But for all we have discovered about sharks, there is still so much we don’t know. “We are just getting started with studying these animals in this area,” said Skomal, who has been concentrating almost exclusively on shark research for the last six years. He invited young people fascinated by the sea to consider a career in shark science, which offers ample opportunities for exploration, such as solving the mystery of white sharks’ 800-meter-deep dives off of the continental shelf. What are they doing down there?

Skomal emphasizes the importance of sharks as apex predators for maintaining sustainable fisheries. Just like terrestrial predators picking off the sick and weak members of a herd, sharks keep fish stocks healthy by predating the less viable members of a fish school. So they are in fact allies of fishermen, being fishermen themselves!

Skomal’s research on the migratory pathways of these formidable fish could be a valuable resource for policymakers in the creation of protected areas where sharks can be safe from hunting and harassment, in order to replenish their populations so critical to the balance of a healthy ocean ecosystem. Every animal matters.

And his advice for humans sharing the water with these grand and intimidating animals? Show common sense and healthy respect. And don’t swim in the deep channels close to shore.