A Marine Protected Area (MPA) is simply a protected marine environment. What does that actually mean and how do people interpret it?
The goal of an Marine Protected Area
The goal of a Marine Protected Area is to let the marine environment recover to a state unaffected by humans. It progresses from the affected stage to its natural stage. This state depends on where it is geographically and the natural equilibrium it would attain based on what surrounds it. In ecological terms it reaches it’s climax community.
An unpolluted Marine Protected Area will accumulate species that would naturally occur in that environment. Polar species for a polar environment, temperate for temperate etc. Those species would, when left alone, essentially fight it out amongst themselves. An ecosystem would develop that is the same as an environment where there are no humans.
The goal of a Marine Protected Area therefore is to allow that to happen. That is to leave it alone. This implies no harvesting and no external anthropogenic influences.
How to create a Marine Protected Area
Firstly MPAs require a local desire (usually national) to protect the area. Laws sometimes come into effect that impose an obligation to local populations to leave the area alone.
At times, military occupation of an island or archipelago ensures that. The environment is off limits as a result of the entire region being protected for strategic purposes. e.g. The Chagos islands.
In rare circumstances such as on Bikini atoll in the Marshall islands, nuclear weapon tests meant that the area was off limits for decades due to being toxic. The depopulated environment recovered despite the initial poisoning.
Once an MPA is announced, it requires people to be kept out of it. This can be achieved by laws alone. But because people break the law, policing of the area is often required. Severe deterrents to would-be poachers need to be publicized and enforced.
This previous post highlights the development of surveillance in Palau’s National Marine Sanctuary.
The degree of protection attained is governed by numerous factors. This influences the outcome and overall ecology of the area.
What happens if total protection isn’t attained?
Firstly, total protection is rarely attained. Nowhere on earth is completely free from human influence. Even the very deepest marine trenches are showing signs of human pollution.
What is Pristine?
If “Pristine” is completely untouched (0% human influence) a Marine Protected Area is trying to get as close to zero as possible.
If you remove one or a significant number of any species, it will have an effect on the entire ecosystem. The ecosystem shifts to compensate for the imbalance. Ecologists call this Trophic Cascade. Trophic levels are essentially what separate plant from herbivore, herbivore from predator.
By reducing the numbers of predators, the prey species populations will increase. (Less are being eaten). This will have an effect on what they in turn hunt or harvest. Once those species populations change, that will then change what they influence. Imagine a line of dominoes that spreads out into a web. One influences another which then influences more again. These changes in populations not only affect populations either side of them of them, but they can also affect the very chemistry of the environment. If there are more or less plants in a system, there would be more or less Oxygen or CO2 available.
Altering the physical chemistry of a system also causes ecological cascades. Increase or decrease in temperature is like changing it’s geographical location. Adding chemicals will also change ecosystems. Farmers increase productivity of their fields with fertilizers. Plant growth can increase if certain compounds of Nitrogen or Phosphorous are added. A process called Eutrophication. Too many plants and not enough herbivores to eat them means systems can be overrun by plant life. This leads to choking and shading what was there before.
Benefits of MPAs
The lack of human harvesting from an MPA means that fish numbers and overall biomass increases. (There are more living things). Eventually the biomass increases to the point where it spreads out into the surrounding waters. This overflow can then be harvested. Within the MPA the fish live longer, breed more often and attain greater sizes. This means their breeding potential is also greater. (Larger fish produce more eggs and milt and therefore more babies.)
Harvesting from MPAs
In some parts of the world, MPAs have been established but the local population still harvests from them. This is sometimes for indigenous cultural reasons. In some locations these cultural excuses are abused. The harvesting is too regular to be sustainable. A overexploitation situation occurs. Local groups harvest instead of allowing the MPA spillover to repopulate the regular fishing grounds.
In a report from Pew Charitable Trusts: By 2018, there are 15,600 Marine Protected Areas globally. 25 million square kilometers. This equates to only 7% of the planets oceans. The aim is by 2020 to have 10% of the oceans protected. It seems we are falling well short of this goal. What is worse is that of the 7%, less than half are actually no take zones. Many are still open to harvesting either by indigenous groups or by commercial operations. So it seems we still have a long way to go.
Humans build bigger and bigger fishing boats. The demand for seafood increases with the human population. The pressure on the worlds oceans increases.
It is vital to respect the natural capacity of the oceans. This capacity is not only of the economic kind. How many fish swim in it or how many we can catch. It is also how well it can recover. Recovery is fastest when the ocean is healthy. A healthy ocean has a greater ability to accept losses, its inhabitants but also losses to its own intrinsic health.
Humans are affecting the very chemistry of the worlds oceans.
Natural damaging cycles such as El Nino events are becoming more common. Natural environments before could recover from these warming periods because they were infrequent. Now these events are happening too regularly for the reefs to fully recover. Each time the damage occurs, the environment has only recovered 50% of it’s potential health. The one step forward two steps back scenario.
The healthiest reef or any environment is one that is in its natural state. This is why it’s so important for us to set aside as much of our Planet as possible. A Marine Protected Area needs to left alone. They should all be left alone and there should be more of them. It is these natural wild spaces that will be the saviours of us all.
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