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When we talk about ports, we usually talk about trade. Ports are the arteries of the global economy, with more than 80% of the world’s goods travelling by sea. They are places of movement, of efficiency, of heavy machinery and tight schedules. Rarely, if ever, do we associate them with wild nature, and even less with biodiversity.
But that perception may be starting to shift. A recent scientific review led by marine ecologist Bénédicte Madon from University of Seville, a partner in the SAFARI project, challenges the long-standing idea that ports are ecological voids. On the contrary, it suggests that ports may be far more biologically rich than we’ve assumed.
Published in Ocean and Coastal Management, the review compiles and analyses more than two decades of scientific literature on biodiversity in port areas. Its conclusion is simple: research on the subject is only just beginning, and our current understanding of biodiversity in these human-made environments is deeply limited. Yet the little we do know suggests that ports could play a surprising ecological role, if we’re willing to look closer.
Until very recently, biodiversity in ports was almost completely absent from scientific agendas. The first studies on the topic appeared in 1999. For years, only a handful of articles were published annually. It wasn’t until after 2016 that scientific interest truly accelerated, a shift likely driven by growing awareness of invasive species, environmental regulations, and the push for more sustainable port management.
Still, the numbers of papers on the topic remain sobering, with less than 20 articles published each year. Out of nearly 18,000 commercial ports and close to 7,000 marinas worldwide, fewer than 400 locations have ever been studied for biodiversity. That’s less than 0.05% of global port infrastructure.
It’s not just that we don’t know what lives in ports, in most cases no one even looked.
And when scientists have looked, their focus has been remarkably narrow. Nearly half of all the studies included in the review were concerned with non-indigenous species, also known as invasive species. These species, often transported via ballast water or hull fouling, are viewed as ecological threats and economic nuisances. Their impacts are real and deserving of attention. But by concentrating so heavily on them, researchers have tended to ignore other aspects of port ecosystems, including native biodiversity and ecosystem functions.
One of the most striking insights from the review is how uneven the research landscape is. Geographically, the majority of studies have been carried out in Europe, and especially around the Mediterranean. In contrast, ports in Africa, Asia, and much of the Americas remain underrepresented despite their size, traffic, and ecological relevance. Even in the best-studied regions, certain types of ports are overlooked. Freshwater ports, for example, have received almost no attention outside of the North American Great Lakes. Marinas, although abundant and often located in biodiverse coastal zones, are also largely neglected in the literature.
The gaps are not just spatial. They’re taxonomic too. Some types of organisms, like barnacles or fouling communities that attach to port structures, are relatively well documented. But others, including fish, crustaceans, sponges, or microscopic life, are barely studied. Mobile or cryptic species are often left out simply because they are harder to observe with traditional methods. Yet these groups are essential to understanding food webs, habitat use, and ecological resilience.
Another missing piece is habitat dynamics. Surprisingly few studies explore how biodiversity in ports interacts with nearby ecosystems. Do ports act as refuges for some species? Are they ecological traps for others? Can they support connectivity with natural habitats, or disrupt it? The answers to these questions remain elusive, not because they are unimportant, but because the research hasn’t been done.
There’s a growing recognition in ecology that urban environments, often seen as hostile to nature, can in fact host surprising levels of biodiversity. Cities are typically located in ecologically rich areas, like river mouths, estuaries, or coastal zones. They contain a patchwork of habitats, some artificial, some remnant, but many of them capable of supporting life. The same, the authors argue, may be true for ports.
In fact, some early studies suggest that ports may host more biodiversity than expected. This is especially true for species that are resistant to disturbance or able to exploit artificial structures. Moderate levels of human activity can, paradoxically, promote species diversity by preventing dominant species from excluding others, a concept known as the intermediate disturbance hypothesis.
Take Sydney Harbour, often described as the most urbanised estuary in the world. Despite its intensive human use, it has emerged as a biodiversity hotspot in Australia, with numerous studies documenting diverse marine communities. Artificial reefs, pontoons, and seawalls have been shown to provide habitat for both native and introduced species. They may even help restore some lost ecological functions, if designed thoughtfully.
The idea that ports could be ecological refuges rather than dead zones is provocative. But it also opens the door to new forms of port management, where infrastructure and biodiversity are not necessarily in conflict.
If biodiversity is present in ports, why don’t we see it? Part of the answer is technical. Monitoring biodiversity in busy, often murky, and restricted port environments is difficult. Traditional methods like scuba surveys or net sampling are time-consuming and limited in scope.
But that is starting to change. The rise of molecular tools, especially environmental DNA (eDNA), offers a powerful new approach. By analysing genetic traces in water samples, researchers can detect species that would otherwise be missed. These methods are faster, less invasive, and more sensitive to rare or elusive species. Yet according to the review, such tools remain underused in port research.
The other part of the answer is cultural. Ports have long been treated as industrial spaces, engineered, managed, and regulated with a focus on efficiency and safety. Environmental issues have historically focused on pollution, air quality, and water contamination, not biodiversity. Even today, most port sustainability frameworks pay little attention to biological life, especially under the waterline.
But this lack of visibility is no longer tenable. As the review makes clear, ports are not just transport hubs, they are also socio-ecological systems, where human activity and ecological processes are deeply intertwined.
Biodiversity plays a central role in ecosystem resilience. It helps buffer systems against shocks, supports key functions like nutrient cycling or habitat stability, and contributes to the long-term sustainability of the environment. In ports, these functions may affect everything from sediment stability to fish recruitment to shoreline protection.
Beyond ecology, biodiversity also matters for people. It shapes the public image of ports, creates opportunities for education and engagement, and contributes to ecosystem services that benefit local communities, whether it’s through fisheries, tourism, or simply a sense of place. Yet very few studies, according to the review, have involved local stakeholders or citizen science. Biodiversity studies remains something done to ports, not with them.
This is where projects like SAFARI come in. By integrating biodiversity considerations into broader climate resilience strategies, SAFARI is helping ports become more adaptive and forward-looking. In our pilot in Port of Seville, for example, Dr Madon and her team will soon deploy hydrophones to monitor underwater noise and its effects on fish. They are also exploring ways to track bird behaviour in response to airborne noise. These initiatives aim not only to understand biodiversity but to make it a working component of port planning.
Biodiversity in ports is still a blind spot, but it doesn’t have to be. The science is advancing, the tools are improving, and the need is clear. What’s required now is a shift in mindset.
We need to stop thinking of ports as places where nature ends and start thinking of them as places where nature changes. Biodiversity in ports may be different, less visible, more resilient, but it’s still biodiversity. And in a time of ecological crisis, we cannot afford to ignore any of it.
As Dr Madon and colleagues write:
“An improved and systematic baseline knowledge of port biodiversity is required to assess how cumulative anthropogenic activities impact local ecosystems and to set up appropriate mitigation measures.”
The message is as simple as it is urgent: we can’t protect what we don’t know.
And right now, in our ports, there is still so much we don’t know.
The insights presented in this article are based on the following scientific review:
Madon, B., David, R., Torralba, A., Jung, A., Marengo, M., & Thomas, H. (2023). A review of biodiversity research in ports: Let’s not overlook everyday nature! Ocean & Coastal Management, 242, 106623.
For more details and the complete list of references, please consult the full article.
