September 1, 2022 — In the spirit of the annual University of Cambridge–led horizon scan of emerging conservation issues, 30 experts from around the world last year put their heads together to brainstorm and assess the potential impacts to ocean and coastal ecosystems over the next decade of a spectrum of human activities across the globe. Their analysis, published in July in Nature Ecology and Evolution, found 15 big issues bubbling to the top.
The increased frequency and severity of fires on land can have cascading impacts as wind and rain carry soot, nutrients, metals and other by-products of burns to coasts and oceans. In some cases these substances can boost the productivity of ocean plants. But the disruptions they cause can also shift the balance of life, making it difficult for some species such as corals to survive.
More severe storms due to climate change, along with development, dredging, thawing permafrost and other factors, are increasing the amount of sediment and nutrients in ocean waters and boosting algae growth. This can reduce the ability of sunlight to penetrate into deep waters and alter water chemistry. The changes can have some benefits, such as reducing coral bleaching. But they also alter species mix and potentially reduce the ability of organisms to soak up carbon.
Acidification Meets Metals
Toxic metals enter the ocean from industrial waste and from disturbance of previously polluted sediments by storms and human activities. As carbon dioxide concentrations increase in the atmosphere, the ocean absorbs more of the gas and its water acidifies. The acidity in turn can increase the ability of marine organisms to take up the metals. In some places where metals are a limiting factor, such as the deep ocean, this can boost phytoplankton growth. In other places, the metals can be toxic to ocean organisms and contaminate bivalves we harvest and eat, potentially causing human health problems as well.
Warming ocean waters are causing ocean organisms to move poleward in search of cooler conditions, with shifts happening five times as fast as those occurring on land. In some cases, other species that better tolerate the heat can move in to fill the void. But in some places at the equator, ocean biodiversity is actually decreasing, with fewer plants and animals around to keep the ecosystem healthy, resilient and able to meet human needs for food.
Fatty Acid Famine
Fish — particularly slow-growing species that inhabit cold water — are a major source of essential fatty acids (EFAs), an important component of the human diet. The fish in turn obtain EFAs from phytoplankton. As climate changes cause ocean waters to warm, phytoplankton will likely make fewer EFAs and fish ranges could shift in ways that reduce their ability to ingest these compounds. This might have adverse impacts not only for human diets but for other ocean life forms that depend on phytoplankton and phytoplankton-eating fish for sustenance.
A protein called collagen is used to make cosmetics and other consumer goods. It’s currently harvested mainly from livestock, but as demand grows, manufacturers may turn to collagen-rich ocean animals such as sponges, jellyfish and sharks. On a positive note, the trend could boost sponge farming, reduce the impact of undesirable jellyfish and provide a use for parts of harvested fish that otherwise would be thrown away. But, concerns revolve around reduced incentives to avoid catching nontarget species in commercial ocean fishing.
Swim Bladder Demand
The market for dried swim bladders, a luxury item in some cultures, is growing. Harvest of fish aimed at meeting the demand already has contributed to the endangerment of at least three species. As populations decline, pressure could shift to related species, creating a “cascading effect” that puts those species at risk as well. And increased demand not only threatens the target species but also nontarget sharks, turtles and other marine organisms that are accidentally caught along with them.
Carbon Mover Removal
As fishing pressure on the ocean increases, mid-depth species are increasingly being harvested. The problem is, these are also the species that help move carbon in the organisms they eat into the deep sea where it can be sequestered for long times. Removing these fish could disrupt the downward movement of carbon, reducing the ocean’s ability to counteract climate change.
A boom in demand for lithium for batteries, such as those used in electric vehicles, has mining interests turning to deep ocean waters that contain significant quantities of the valuable metal. With emerging lithium-concentrating technologies, extraction is a looming reality — potentially threatening species living in rare and extreme environments.
More the Merrier?
As humans increasingly turn to the oceans for food, energy and more, opportunity arises to cluster enterprises. This can create economies of scale and reduce habitat disruption. The researchers note that we need ways to evaluate the relative costs and benefits of colocation to minimize habitat disruption and threats to biodiversity, and to avoid sub-optimization, such as expecting the ocean area beneath a floating wind turbine to be an ideal aquaculture site.
Cities at Sea
Talk of building towns in the ocean has increased in recent years. Benefits to humanity would be new energy sources, abundant water for hydroponic agriculture and more, but governance challenges would be likely. It’s a mixed bag for ocean life, too: Floating cities could help anemones, sea urchins and other marine organisms that live at least part of their life cycle on rocky intertidal surfaces migrate to safer places in the face of climate change. But it also could facilitate the spread of biodiversity-threatening invasive species.
Growth in electric vehicles and other “green” technologies that require batteries is increasing the use of cobalt, nickel and other trace elements. These elements pose a contamination risk to near-shore ocean sediments as they leach from production sites and landfills, with potential implications for sea life.
It’s hard to track the movements of marine organisms because radio signals transmit poorly through water. Now, new technology known as underwater backscatter localization (UBL) has potential to dramatically expand our ability to study undersea life. UBL could benefit conservation by enhancing the ability to understand distribution and behavior of ocean animals. But it also will be important to consider how the presence of the devices might adversely affect them.
The use of robots that mimic life forms for ocean research is growing. Because so-called “soft robots” aren’t limited by the need for pressurization like rigid robotics, this may boost deep sea exploration. At the same time, it could disrupt previously untrammeled environments and harm marine life by using novel organisms as fuel or being ingested by indiscriminating animals.
Biodegrading Into What?
Biodegradable plastics are beneficial because they can prevent the buildup of trash in the ocean environment. But what about the components the materials degrade into? The speed with which such materials are entering the market due to consumer demand has in some cases limited testing of the impacts of degradation of the products, opening the door to potential new problems with toxicity within the marine environment.