Often we associate marine-conservation projects with remote parts of the world. But in reality, some of the most important marine-conservation programs take place in an urban environment.

Often, when we think of marine conservation projects, we think of initiatives carried out in remote parts of the world. In reality, some of the most important marine conservation programs take place in an urban environment where the damage done by human activity is most severe. Here we’ll take a look at three marine conservation projects currently taking place in some of the world’s busiest waterways.

Oyster restoration, Bronx River estuary, New York

In the past, oysters were abundant in the New York/New Jersey harbor. They constituted a major resource for both natives and early settlers. Because of over-exploitation and rocketing estuarine pollution after the Industrial Revolution, oysters that once numbered in the billions have almost completely disappeared. Today, the Oyster Research Restoration Project, run by the Hudson River Foundation, is attempting to reintroduce the beleaguered oyster to New York’s waterways. In June 2013, a coalition of more than 30 different organizations, including the Hudson River Foundation, the Bronx River Alliance and NYC Parks, began an oyster restoration project in the Bronx River estuary at Soundview Park.

The organizations began by depositing 125 cubic yards of clamshells in the river around existing rock outcroppings. These were intended to provide a substrate for a new oyster colony, and in the process, created the largest expanse of sub-tidal habitat in the lower Hudson River estuary. Several months later, the coalition added 100,000 oyster larvae (also known as spat-on-shell) to the reef to kick-start the colony’s growth. No one will farm these oysters for food or for their pearls. Instead, they will improve the water’s quality, as each oyster filters up to 50 gallons every day. The oyster reef will also serve as a foundation for the recovery of other estuarine species, by providing fish and invertebrates with natural shelter.

The Soundview Park reef is just one part of a comprehensive restoration plan. Further goals include the successful installation of 20 acres of oyster beds by 2020. The oyster reefs, both in the Bronx and in other areas of the New York/New Jersey harbor, are also intended to provide protection for the coastline by absorbing storm energy.

Seagrass preservation, Sydney Harbor, Australia

As habitats go, seagrass beds are one of the most critical to the health of the marine environment. They support a wide variety of species, some of which use the seagrass as a source of food. Others use the seagrass either as a temporary nursery or a permanent home. Seagrass beds also stabilize ocean sediment. In this way, they help prevent coastal erosion and act as an invaluable sink for carbon dioxide. Historically, seagrass beds were prevalent on the Australian coast, and particularly, in Sydney Harbor. Today, however, declining water quality, dredging activity, and coastal construction have decimated the beds. More than 50 percent of Sydney’s seagrass meadows have disappeared in the last 60 years. Scientists now consider some species of grass, such as the strapweed, endangered.

In Sydney Harbor, researchers from the University of New South Wales and the Sydney Institute of Marine Science are working hard to restore the waterway’s seagrass beds. Research methods include taking sediment samples, performing video transects and fish counts, and making 3D models of the seafloor. Researchers have identified boat moorings as a major cause of seagrass degradation in the harbor. Boats typically moor to a concrete block via a heavy chain. This scours the seagrass and the sensitive sediment below as the boats move with the current and tide. Traditionally, the harbor has been a haven for recreational boaters. The waterway currently hosts 4,850 private moorings as a result.

A solution, in the form of a seagrass-friendly mooring, is at hand. Designed to eliminate the destruction caused by traditional moorings, it won the ABC New Inventors program. The mooring has replaced traditional ones in Manly Cove, where a team of researchers from the University of Technology, Sydney, is currently evaluating its effectiveness.

Harbor porpoise conservation, Thames estuary, United Kingdom

Scientists declared the heavily polluted Thames estuary biologically dead in the 1950s. The river runs through the center of London and is one of the busiest waterways in the world. Since the 1950s, however, it’s experienced a dramatic recovery thanks to a series of extensive restoration projects. It is now so diverse that it provides a home for 120 species of fish including, incredibly, the short-snouted seahorse. A variety of water birds and marine mammals also inhabit the river. Many of these mammals inhabit the tidal reaches of the estuary, and include the harbor seal, the grey seal, and most recently, the harbor porpoise. Previously, evidence of the harbor porpoise in the Thames was purely anecdotal. But in 2015, a coalition of research groups launched the first-ever survey of this species in the estuary.

The harbor porpoise is the U.K.’s smallest cetacean species. It’s under threat in the greater North Sea and Celtic Sea thanks to a variety of factors. These include noise pollution, entanglement and degraded water quality. The existence of this species in the Thames not only proves how much the river has recovered, but also offers potential for more effective conservation as a result. Marine Conservation Research International, the Zoological Society of London and the International Fund for Animal Welfare are the main forces behind the ongoing research of the Thames harbor porpoise population. Together, they are conducting acoustic and visual surveys. They also monitor the waterway’s marine litter, man-made noise and fishing activity.

It is hoped that this project will yield a better understanding of harbor porpoise distribution. Associated outreach programs will also raise awareness of the species’ existence in the estuary. Scientists will use collected data to inform future conservation activities, and to ensure that future urban development along the Thames considers the porpoises’ wellbeing.

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