Biodiversity in marine and coastal ecosystems is under threat from well-known factors, such as climate change, ocean acidification, pollution and overexploitation. However, there are also many emerging issues that are poorly understood and that may have additional significant impacts on marine biodiversity in the future.
In light of the fact that the United Nations Decade of Ocean Science for Sustainable Development (2021–2030) is now underway, a team of 30 experts from 11 different countries and a range of subject backgrounds has convened to conduct the first ever Marine and Coastal Horizon Scan. The horizon scanning process aims to identify lesser-known issues with potentially serious impacts that may affect marine and coastal biodiversity conservation in the next 5–10 years.
Experts in this horizon scan were asked to list issues that they thought could become critical for marine and coastal biodiversity in the near future, but that had received little or no public attention to date. The initial list contained 75 emerging issues but, through a series of discussions and votes by the panel of experts, this was whittled down to 15 critical issues that fell into three categories: ecosystem impacts, resource exploitation and novel technologies.
In their report, published in the journal Nature Ecology & Evolution, the panel of experts listed issues such as the effect of wildfires on coastal ecosystems, the increased toxicity of metal pollution due to acidification, and the ‘empty zone’ in the tropics due to species’ migration away from warming waters. All these factors could potentially have significant impacts on ecosystems in the near future.
“Marine and coastal ecosystems face a wide range of emerging issues that are poorly recognized or understood, each having the potential to impact biodiversity,” said study first author Dr James Herbert-Read of the University of Cambridge. “By highlighting future issues, we’re pointing to where changes must be made today – both in monitoring and policy – to protect our marine and coastal environments.”
Under the category of resource exploitation, the panel identified trade in fish swim bladders and marine collagen as potential issues affecting biodiversity in future. They also expressed concern that fishing activities may become increasingly focused on species in the mesopelagic zone, at depths of between 200 and 1,000 meters. Although these fish species are not usually edible, they can be used to make fish meal for aquaculture and fertilizer purposes. This, say the experts, would affect the transport of carbon from the atmosphere to the very bottom of the oceans, making the ocean a less effective carbon sink.
“There are areas where we believe immediate changes could prevent huge problems arising over the next decade, such as overfishing in the ocean’s mesopelagic zone,” said study co-first author Dr. Ann Thornton. “Curbing this would not only stop overexploitation of these fish stocks, but reduce the disruption of carbon cycling in the ocean – because these species are an ocean pump that removes carbon from our atmosphere.”
The experts also warn that the nutritional content of fish is declining as a consequence of climate change. Essential fatty acids tend to be produced by cold-water fish species, so as climate change raises ocean temperatures, the production of these nutritious molecules is reduced. Such changes may have impacts on both marine life and human health.
The potential negative and positive effects of new technology on marine biodiversity include the development of more sophisticated tracking equipment that would help scientists to understand the movements of deep-sea species, and the use of soft robotics for marine research. The report also listed the possible effects of newly developed biodegradable materials to replace plastics, pointing out that definitive research has not yet been conducted on the effects of these potentially toxic materials on marine organisms.
“Governments are making a push for the use of biodegradable materials – but we don’t know what impacts these materials may have on ocean life,” said Dr. Herbert-Read.
Horizon scans serve the purpose of identifying lesser-known or novel issues that could soon have impacts on marine and coastal biodiversity. The study authors hope that this will raise awareness and encourage research and investment into these issues before they become seriously harmful.
“Our early identification of these issues, and their potential impacts on marine and coastal biodiversity, will support scientists, conservationists, resource managers, policy-makers and the wider community in addressing the challenges facing marine ecosystems,” said Dr. Herbert-Read.
The researchers say horizon scans act as signposts that can bring issues to the forefront of public attention before they become pressing, making it possible to take pre-emptive actions. For example, a horizon scan conducted in 2009 identified microplastics and invasive species as potential issues that could harm biodiversity. In fact, after the 2009 Horizon Scan, 71 percent of the issues identified received increased research and investment from scientists, funders, managers and policymakers in order to understand their potential effects.
“The scale of the issues facing marine and coastal areas emphasizes the need to identify and prioritize, at an early stage, those issues specifically facing marine ecosystems, especially within this UN Decade of Ocean Science for Sustainable Development,” concluded the study authors.