Written by: Nika Stagličić, PhD, Senior Research Associate at the Institute of Oceanography and Fisheries
Who among us knows how the underwater world would look without everything we do to it and without all the ways we use it? Can we even imagine? And do that kind of places still exist?
With this idea in mind, National Geographic launched their Pristine Seas expedition about fifteen years ago. Aiming to document, explore, and protect the last remaining untouched marine wilderness areas, they ventured to remote, isolated, and uninhabited islands in the middle of the Pacific (such as parts of the Equatorial and Pitcairn archipelagos).
How do things really work underwater?
What they saw while diving there turned traditional beliefs about marine ecosystems upside-down, revealing how these systems function and appear in their original, natural state. Researchers described the underwater world of these untouched reefs as a lush coral jungle, so dense there was no room for sand, teeming with all forms of life. Until this expedition, the commonly accepted belief was that marine communities looked like a pyramid, with the largest biomass of organisms at the base of the food web. On coral reefs, this means an abundance of fish, like parrotfish or surgeonfish that feed on algae, and various small fish that eat planktonic organisms, known as herbivores and planktivores. There is then a decreasing biomass of carnivorous fish, with the smallest biomass being top predators such as sharks, large snappers, groupers, and tuna.
However, this kind of perspective is a consequence of how long we have been impacting and altering the sea, which led to a completely distorted reference point for what is natural and how underwater ecosystems function.
In truly natural, untouched underwater areas, the biomass pyramid is inverted. There, top predators make up most of the total fish biomass, up to 85% on some reefs. The question that arises here is: how is that possible? How does 15% of the fish biomass at lower trophic levels support so many predators above them? How does 85% survive on 15%? The factor to consider here is time. Relationships in the food web are like gears in a clock mechanism, where the large one moves slowly and the small one moves quickly. Fish at lower trophic levels grow and reproduce very rapidly, while sharks at the top live very long and reproduce slowly. Their biomass remains relatively constant over time, supported by the rapid reproduction and high turnover of biomass at lower levels.
In addition to the inverted community structure, these areas are richer and more numerous, with far more organisms overall. Many herbivores keep the reef clean, allowing coral polyps to attach more easily and grow. Besides having more fish, there are also other key ecosystem components, like various shellfish that filter seawater and keep the reef clean of bacteria, viruses, and other pathogens.
Predators as indicators of ecosystem health
The abundance of top predators, especially sharks, which control their prey populations, ultimately enables a healthier ecosystem with a more balanced and diverse distribution of organisms at all pyramid levels. Fishing, especially nowadays, can easily, quickly, and efficiently remove predators from the ecosystem, triggering a cascade of changes. And it doesn’t take much.
Comparing these remote, uninhabited atolls with similarly isolated, nearby inhabited islands – even with populations as small as fifty people, like on Pitcairn Island – reveals drastic differences. Coral coverage is lower, and most corals are dead, overgrown with algae. Besides that, most fish are small, smaller than the length of the pencil researchers used to record them, and there are almost no sharks. For example, Kiritimati, also known as Christmas Island, where Captain James Cook arrived on Christmas Eve in 1777, was described as an island swarming with sharks. Today, with a population of about 5,000, researchers in 250 hours of diving did not observe a single shark.
A glimpse into the past and future
These few untouched places are time capsules, taking us hundreds of years back and showing us what we had and how we lost it. Simultaneously, they open a portal to a better future, showing us how to restore and what to strive for. These few remaining pristine areas are crucial, as they are our only examples of an underwater world without human impact. They reveal how seas and oceans truly function, helping us understand the real impact of our activities and teaching us about recovery and restoration possibilities.
Fishing, though significant, is not the only factor disrupting natural balance in underwater communities. These islands, spared from our immediate presence and fishing, are not protected from other environmental threats we create – pollution and global warming, i.e., climate change. However, research on these places with rich and complex ecosystems, including an abundance of top predators, has revealed fascinating insights.
On coral reefs worldwide, episodes of bleaching, massive coral die-offs due to elevated seawater temperatures, are becoming more frequent and severe. These episodes can be caused by pollution and excessive sunlight. It turns out that recovery capabilities from such lethal heatwaves differ drastically, depending on the integrity of the coral reef ecosystem. And it’s not the case that these pristine atolls weren’t affected by prolonged periods of elevated temperatures, as bleaching there also impacted at least half of the corals. However, because these reefs have such a high abundance of fish, including herbivores that continually graze on algae, keeping the reef clean, the corals were able to recover. In contrast, on reefs lacking an abundance of fish, algae quickly overwhelm and cover the coral skeletons, preventing new coral polyps from establishing and allowing the corals to recover. Therefore, the more complete and complex the food web is, the more resilient it is to external influences and the more likely it is that such an ecosystem will recover. These insights shouldn’t surprise us at all; they are common sense. Apply the same to yourself, and you’ll see that for an ecosystem, whether marine or terrestrial, and for us as individuals, the same principle holds true: the healthier and more complete we are, the more resilient we are and the easier it is for us to recover from various diseases and other adversities (disorders).
We need marine protected areas
The next question and challenge is whether such pristine, natural, healthy, and resilient nature can be achieved where we are present, not just in remote and isolated places free from our direct impacts. Science is quite clear here, and the conclusion that it benefits not only nature but also us, is based on models and real-life examples and experiences.
The way to bring the past and what we have lost back into the present, to restore life and habitats in the seas and make them healthy and productive involves protection. Not everywhere, as that is unrealistic and impossible, but rather by strategically selecting certain areas. And protection in these areas must be complete if we want to get desired benefits from them. Half-measures are ineffective. Marine protected areas that we leave to nature, removing all forms of fishing and other destructive human activities, are often called marine reserves or no-take zones.
The biomass of fish within such reserves increases by an average of 500% over ten years, compared to surrounding unprotected areas. And when fish and other organisms recover to such an extent, when their numbers and average size grow, it triggers an entire cascade of ecological changes that lead to the restoration of the entire ecosystem. These beneficial changes do not occur in partially protected areas that allow certain forms of fishing in limited amounts. There is simply no effective way to regulate fishing — no matter how restrictive — that could restore or maintain significant quantities and sizes of fish like we see in no-take zones.
Consider the example of the previously mentioned Pitcairn Island, where even just fifty people, using only traditional fishing methods, had enough impact to drastically alter and impoverish the marine ecosystem. However, when we manage to create rich and untouched oases, they can restore surrounding areas as well. The more fish in the reserve, the more benefits for us. In addition to the extraordinary abundance of fish spilling over into neighbouring unprotected areas, large female fish accumulated in the reserve produce significantly more eggs, creating numerous offspring, many of which are also dispersed around. Thus, fishermen near the reserve catch more fish.
Example of good practice: Medes Islands Marine Reserve
The impressive recovery of fish that occurs in reserves also attracts many divers, creating new jobs and business opportunities and bringing significantly more economic benefits than the absence of protection.
One of the examples in the Mediterranean of how marine reserves strongly restore biodiversity while also creating additional economic opportunities and profits is the Medes Islands. The sea around this small archipelago of seven islets, located near the coast of Catalonia in northeastern Spain, was an underwater desert before protection was established in 1983. The sea, that was previously overfished, transformed with protection and time into an area with one of the highest fish biomasses in the Mediterranean, becoming a tourist and diving mecca. Considering only the revenues from fishing and diving tourism, without including the associated economic benefits from hospitality, accommodation, and other tourism-related branches, the value of the reserve surpassed the profits from before protection was established in just five years. It is estimated that today the reserve directly provides more than 200 jobs and over 16 million euros in annual revenue (mostly from diving, snorkeling, and glass-bottom boat tours). The main reason why tourism contributes the most to the local economy — much more than fishing — is precisely the abundance of fish, which is a result of the Medes being one of the few well-managed and controlled marine reserves in the region. The very fact that the number of dives at the Medes Islands had to be limited (as excessive visitation can be counterproductive; for instance, too many divers in one place can damage marine fauna) clearly indicates that there is high demand and not enough successfully managed marine reserves to accommodate all those divers and visitors who want to catch a glimpse of the Mediterranean as it once was (and as it looks now when well managed).
We need at least 30% marine protected areas
Since the reserve’s waters cover only 1 km², the Medes Islands teach us that even a very small area can produce great ecological and economic benefits. This insight is especially important because most coastal areas are densely populated, making the complete exclusion of fishing and other forms of exploitation over large areas often unfeasible. The establishment of several smaller reserves is more likely.
But how much of the total area should be protected if we want this protection to benefit and reflect on the entire ecosystem (including benefits for us)? Today, not even 3% of the seas and oceans are fully protected from fishing and other destructive human activities. Research shows that we need at least 30% of areas under such protection to save marine life, and ourselves.
The argument that we cannot protect more due to ensuring enough food and jobs is wrong. The real enemy of food security and jobs in fisheries is the continuous and excessive exploitation of the resources on which this way of life depends. In fact, if we want to catch more fish, we must protect that 30% of the sea so it can regenerate the remaining 70%. So, if we want to secure a bright future for fisheries, we need to manage them more responsibly and stop fishing everywhere and taking more from the sea than it can naturally replenish. Protection provides immense value; we just need to give nature enough space to recover from our exploitation and continue to provide us with valuable resources. This issue is often compared economically. Protection works like a savings account in a bank, where the protected area is the principal that we set aside to generate interest, while fishing everywhere is like a checking account from which everyone withdraws, and no one deposits.
Marine protected areas – beneficial for all, yet there is not enough of them. Why?
If protection is so unequivocally beneficial, why aren’t there more marine reserves? Why do the existing ones often not function according to this universally positive scenario? There are many reasons.
Lack of knowledge and awareness commonly underlie many issues we face, including this one. There is a significant lack of awareness that we are over-exploiting the ocean to a dangerous point of no return. Many people, including policymakers and the public, might not fully understand the importance of marine protected areas and the benefits they provide or even have misconceptions that protection harms economies and food security. Educating the public about the values and importance of preserved underwater ecosystems and the benefits they provide to everyone, including us humans, is crucial for gaining support for conservation concepts. In that case, the role of science and organizations (such as Sunce) is to spread knowledge and information and to persistently advocate for different and better ways of functioning.
Additionally, most societies are driven primarily by short-term economic interests. Applied to marine protected areas, this means entrenched interests with strong political connections, like the oil lobby or industrial fishing, resist greater protection and limiting their activities, prioritizing immediate profits over long-term sustainability. Local fishers on an individual level often choose the status quo because protection can result in short-term losses (due to reduced fishing areas), and they typically do not have secure and exclusive access to the benefits created by the existence of a marine reserve.
This brings us to issues with management and funding models for marine reserves. Establishing protected areas often occurs through a centralized approach, via national or regional authorities, with public funds and without significant involvement or authority of local communities. This approach can result in a lack of support and resources for successful protection implementation. Various forms of local public-private partnerships have proven to be more successful models for establishing and managing protected marine areas. And how it works in practice, read in the article about the Islet Apo in the Philippines.
To conclude, for marine reserves to fully realize their potential, a paradigm shift is needed – how we think about these areas, how we establish them, and how we implement them. If we understand the nature of nature, change our approach, and give it opportunity to be human-free, positive impacts on its conservation and human well-being can be achieved.