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Planet in Crisis: Dead Zones

November is famous for starting a month with spooky vibes. This is known to everyone as the month to remember the dead. But there is a type of “dead” that we need to remember throughout the years. And this type of “dead” is detrimental to our environment. This is known as Dead Zones.

Our dying planet

We live in a livable planet, which is the Earth. There are tons of reasons of why it is a livable planet. According to National Geographic, the Earth is a livable planet because of the location of its location, the sun as the stable and long-lasting star, the right distance from the sun, the appropriate things to host a dynamic core, a big moon and the ozone later.

And what is more amazing about our living planet is the environment that it has. The water, land, and air support the lives of many living creatures that inhabit it. It also provides adequate food, shelter and comfort for everyone. This has sustained the living creatures for years and perhaps for the coming years to come.

However, due to some human activities, this livable planet could be dying. The National Geographic noted that the human activities impact the physical environment through overpopulation, pollution, burning of fossil fuels, and deforestation which are some of the reasons of creating changes that triggered changes on climate, soil erosion, poor quality of air, and undrinkable water.

The Intergovernmental Panel on Climate Change (IPCC), comprised of more than 1,300 scientists from the United States and other countries, foresees that the temperature will rise of 2.5 to 10 degrees Fahrenheit over the next century. In the article from NASA, it was stated that according to IPCC, “the extent of climate change effects on individual regions will vary over time and with the ability of different societal and environmental systems to mitigate or adapt to change”. It also added, “the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time”.

In the same article, it also noted the future effects of this global climate change based on the third and fourth National Climate Assessment Reports that in the United State alone can result  long term effects such as:

  • Change will continue through the century and beyond.
  • Temperature will continue to rise.
  • Frost-free season will lengthen.
  • Changes in precipitation patterns will occur.
  • More droughts in the southwest and heat waves
  • Sea level will rise from 1 to 8 feet by 2100.
  • Arctic will likely become ice-free.

Another issue is also arising that is connected to the condition of our planet. It is the occurrence of a deadly situation in some of the areas in our world’s ocean. This is the existence of Dead Zones.

What are Dead Zones?

Dead Zones speak danger as much as they sound. Just by hearing or reading them makes you think of some truths about the environment and the planet we are living with. You would not basically feel as relaxed as you were since there are situations that make the planet less livable. But before anything else, it is necessary to get the facts right. So, what are really dead zones?

According to National Ocean Service, a dead zone is also known as hypoxia. Dead zone or hypoxia refers to reduce level of oxygen of the water. It is where lesser oxygen dissolves in water resulting to the death of many marine life. The inadequate level of oxygen supply in bodies of water is alarming since it is essential to support balance as well as life in the marine ecosystem.

The Science Daily defines dead zones as areas in the world’s oceans that have low oxygen which have been noted by oceanographer since 1960.

Dead zones have also classification and quite characteristics. According to Thoughtco, here are the different types of dead zones:

  • Permanent Dead Zones are deep water occurrence that rarely 2 milligrams.
  • Temporary Deep Zones are short lived dead zones lasting for hours or days.
  • Seasonal Dead Zones are annually occurring typically in warn months of summer and autumn.
  • Diel cycling hypoxia is a specific seasonal dead zone that only become hypoxic during the night.

National Geographic puts dead zones simply as “deadly, where little to no life can survive in their oxygen-depleted, or hypoxic, waters.”

Dead zones around the world

Now that you know what dead zones are, it is also equally important to identify some areas which are now known as dead zones of our planet.

Dead zones mainly occur in coastal regions near watersheds, particularly in high population areas. According to Robert Diaz, a biological oceanographer at Virginia Institute of Marine Science, “Dead Zones were once rare. But now they’re commonplace, and there are more of them in more places.”

In the past based from the limited surveys, there are 49 dead zones in the 1960s, 87 in the 1970s, and 162 in the 1980s. The dead zone global count is 405 as what Diaz said, and most probably increasing from that number today and beyond.

Out of the 405 areas of dead zones, here are some of the common and known places where they occur:

Baltic Sea

Researchers from Baltic Nest Institute published “Dead Zones have increased by more 10-fold in the last centuryin one of Proceedings of the National Academy of Sciences of the United States of America (PNAS) issues.

They reported that the Baltic Sea has the a dead zones that have grown from approximately 5,000 square kilometers to more than 60,000 square kilometers in recent years.

Chesapeake Bay

In the 1970, the Chesapeake Bay, East Coast of the United States, had dead zones. The urbanization and agriculture resulted to Chesapeake’s high levels of nitrogen are caused. This is given the fact that the western part of the bay is full of factories and urban centers that releases nitrogen, while the eastern part of the bay is a center of poultry farming, which produces large amounts of manure that also contributes to green house gasses.

Although, there were efforts done by Chesapeake Bay Foundation to improve and mitigate the water quality of the bay and pollution, it still has a dead zone which size varies depending on the season and weather.

Elizabeth River, Virginia

The Elizabeth River has been polluted by nitrogen and phosphorus. The shipbuilding industry, the military, the world’s largest coal export facility, refineries, loading docks, container-repair facilities and others contribute toxic deposit to it. It had been off-limits since the 1920s.

Thousands of tons of contaminated sediments were actually removed by an organized group in 1993. It was also noted that fishes were not able to exist on this said area. However in 2006, a 35-acre biological dead zone called Money Point was dredged out, and this let fish return, and the wetland recover.

Lake Erie

The central part of Lake Erie has a dead zone from east of Point Pelee to Long Point and stretches to shores in Canada and the United States. Since the 1950s to 1960s, this dead zone caused concerns and during the 1970s, both Canada and US made policies and programs to reduce runoff pollution into the lake as to help prevent the dead zone growth.

Lake Erie’s oxygen level is poor. The small area to the east of Long Point is the only has better levels of oxygen. And this has impacted the fisheries industry in the area.

Gulf of Mexico

Another area that has dead zone featured in United States Geological Survey (USGS) in June 2012, the Gulf of Mexico dead zone is the area of temporary hypoxic bottom water that occurs most summers off the coast of Louisiana in the Gulf of Mexico. According to Louisiana Universities Marine Consortium (LUMCON), this is the largest recurring hypoxic zone in the United States. The drainage area for 41% of the continental United States is the Mississippi River pumps high-nutrient runoff such as nitrogen and phosphorus into the Gulf of Mexico.

Moreover, the 2009 fact sheet created by NOAA reported, “seventy percent of nutrient loads that cause hypoxia are a result of this vast drainage basin”. This is further aggravated since millions of tons of phosphorus are being released every year. The Gulf of Mexico in the United States has the second largest dead zone with almost 6,000 square miles in size. While the the largest dead zone in the world lies in the Arabian Sea, covering almost the entire 63,700-square mile Gulf of Oman.

Causes of dead zones

The reasons behind dead zones may vary. It may be caused by natural phenomenona. However they are also triggered by human activities such as ocean pollution and agricultural practices.

One of the main cause is Eutrophication. Eutrophication is the condition when the body of water becomes so abundant with minerals and nutrients such as phosphorus and nitrogen. Eutrophication is often induced by the discharge of nitrate or phosphate-containing detergents, fertilizers, or sewage into an aquatic system.

The abundance of nutrients can result to algal bloom or an increase of Phytoplankton. Phytoplanktons are microscopic algae that contain chlorophyll which require sunlight to grow that is similar to a plant. They love nutrients like nitrogen and phosphorus. And this can make phytoplanktons grow rapidly and faster. However, this rapid growth can cause depletion of oxygen. You might be asking how it is possible when basically they tend to produce oxygen. While phytoplankton produce oxygen during photosynthesis, they can still cause depletion of oxygen in the water because of decomposition.

FOr instance, the small animals that spend most of their lives drifting in water known as zooplankton eat  the abundant phytoplankton, and these zooplankton become the food of small fish. Thus, the rapid increase in algae produces more animal waste—feces and plankton corpses. These animal waste and dying algae would also be munched by bacteria on the ocean floor. The bacterial process of decomposition sucks up oxygen from the water and therefore lowering the amount of oxygen remains in the water.

Another reason is the stratification.  According to the Free Dictionary, ” stratification is the vertical distribution of water density in bodies of fresh or salt water and is characterized by the vertical density gradient. The greater the increase in density with depth and the greater the vertical gradient, the higher the stability of the stratification. When the vertical density gradient is small or the density decreases with depth, the stratification is unstable”. For instance, the freshwater washed into the Gulf from the Mississippi watershed, floats near the surface of the ocean because it is less dense, and therefore more buoyant than the saltwater and because of this layering of water, it prevents oxygen mixing between the freshwater and saltwater layers resulting again to lesser oxygen in the water.

Another explanation was also provided by Virginia Institute of Marine Science (VIMS):

“Stratification occurs frequently in the deeper waters of Chesapeake Bay during the summer doldrums, when calm conditions minimize physical mixing of the water column by surface waves. Density differences also encourage stratification. In Chesapeake Bay, input from freshwater tributaries often forms a low-density surface layer atop the saltier, denser bottom waters that enter the Bay mouth from the Atlantic Ocean… Shallow waters are much less likely to stratify compared to deep waters, and are thus less likely to develop hypoxia. First, shallow waters tend to be well-mixed by winds and tides. Second, waters that are shallow and clear enough to allow light to reach the bottom can support primary producers such as phytoplankton, algae, and seagrasses that release oxygen during photosynthesis.”

Global warming can also cause dead zones as global warming can also cause warming climate which was noted in some reports. For instance, in the Mississippi watershed, warming climate could lead to more rainfall which exacerbate nutrient run-off problems and warm water, which carries less oxygen, make it easier for dead zones to form. Also, there are more scientific evidence that prove global warming is one factors of algal bloom.

Effects of dead zones

Effect of dead zones could be clearly seen as there will be changes in the biodiversity of marine life. It can cause imbalance to marine ecosystem as well.

The inadequate level of oxygen in the water affects marine creatures both mobile organisms, such as crabs and fishes, and the immobile organisms. Both organisms can die due to this. Even animals that are known to develop in low-level oxygen cannot be spared from dying. One example is a study that found female Atlantic croaker fish developed reproductive organs more similar to testes instead of ovaries when living in hypoxic conditions. This kind of impact or effect of hypoxic condition on the reproductive organ of this organism could negatively impact its population which if not mitigated would actually face extinction.

Another obvious effect of dead zone is the shifting or migration marine species to livable water, where they can get enough oxygen to sustain life. The massive mortality and migration of the marine species decrease the biodiversity in the said area where dead zone occurs. In the study, “Gulf of Mexico Hypoxia A.K.A. The Dead Zone” by Rabalais et al stated, “the reestablishment of benthic communities depend upon composition of adjacent communities for larval recruitment which results in a shift towards faster establishing colonizers with shorter and more opportunistic life strategies, potentially disrupting historic benthic compositions.”

There could also an economic impacts since it could affect the fisheries productions. For instance, the inadequate level of oxygen in the water could affect the growth of shrimp that could not sustain the demand of the consumers who prefer bigger sizes. Another example is the assertion that the dead zone creates a dilemma on the lucrative commercial and recreational fisheries in the Gulf of Mexico.

In fact, according to Lisa M. Fairchild, a Master of Science at the University of South Florida, in her work “The influence of stakeholder groups on the decision-making process regarding the dead zone associated with the Mississippi river discharge“, “In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed about $10 billion to the Gulf economy, taking 22 million fishing trips”.

Given this, there are chances that it also affects small-scale fishermen in some areas specially the marginalized as dead zones can be formed wherever the of some human activities that causes environmental damage can occur. And this can, sooner or later, affect the health of those marine creatures but also the public health of human beings.

Solutions to dead zone

Everyone can take part in creating a solution to address dead zones. From a pool of experts to a certain individual, like you, can participate.

According to Virginia Institute of Marine Science (VIMS), to reduce the size and number of low-oxygen dead zones in coastal waters is to lessen the input of nutrients, which means lesser phosphorus and nitrogen among others,  into estuaries or  a water passage where the tide meets a river current and the coastal ocean. It was also stated that nutrient-reduction strategies are a key part of ways to address dead zone as in the case of the restoration of the health of Chesapeake Bay.

Moreover, the researchers at VIMS collaborated with their colleagues around the world in addressing the problem of marine dead zones by understanding how dead zones form; deciphering how dead zones affect marine organisms and communities; monitoring and modelling dead-zone prevalence and duration; developing criteria to gauge the severity of dead zones; and providing guidance to policymakers and resource managers concerning the land-use and water-quality strategies needed to reduce dead-zone formation. They also collaborated in coming up with strategies in reducing the duration and size of dead zones dubbed as total daily maximum load or TMDL for the nutrients of nitrogen and phosphorus.

In fact in 2020, VIMS researchers work with colleagues in state and federal agencies in coming up with the TMDL plan known as the Chesapeake 2000 Agreement which consists of the following:

  1. Develop the TMDLs needed to meet water-quality standards.
  2. Develop a TMDL implementation plan.
  3. Implement the TMDL plan, and monitor water quality to determine if water-quality standards are being attained.

This TMDL plan can be replicated not just in the US but also in other countries whether they have or have not dead zones. Policymakers around the world can also refer to the work of VIMS as model to be able to address the issue with regard to dead zones. Aside from the VIMS efforts, there are also more studies that policymakers as well as advocates can learn from in planning for mitigation.

As mentioned above, individuals like you can also help reverse the problem of dead zones by considering the following the ideas:

If you are a gardener or farmer, it is best to avoid fertilizers as much as possible and find ways of how to improve soil nutrients without much use of fertilizers. Nowadays, there are more practices on how to replenish soil.

  • Conserve water and lessen consumption as much as possible to lessen impact on watershed and ground water. Also, avoid polluting water areas as this can also reach to ocean that may further cause formation of dead zone.
  • Make efforts to lessen pollutants that may contribute to air pollution. Beaware of the impact of the carbon footprints in your household, transportation and even in a workplace and even down to consumptions of some cosmetics and more.
  • Go zero waste.
  • Be aware on the key issues that may affect the environment, economics and politics. Because, there are times where economic development may affect the environment negatively such as construction of dams on protected areas or ancestral domain of indigenous people for example, the controversial construction of Kaliwa Dam in the Philippines. there are also policies which can help mitigate and improve the environment on the other hand, there are also policies that would harm the environment. Thus, your awareness can help you to participate in creating direct impact to the environment.

Dead zones are basically a collection of malpractices of human activities. Dead zones are results of our failure to provide attention to the habits that we are not aware in beginning. However, our collective efforts can make a difference in reversing dead zones into livable zones.

What do you think?

Written by Moderator

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