Tag: research

How Are Diatoms Affected by Ocean Acidification?

Posted on by Team Writer

Ocean acidification occurs when the pH level of seawater decreases, which is most frequently caused by the ocean absorbing excess CO2 from the atmosphere. Ocean acidification has negative effects on a variety of ocean ecosystems and life forms, including diatoms, a type of phytoplankton characterized by glass-like cell walls made of silica.

This article will explain how diatoms are affected by ocean acidification, and will discuss the importance of diatoms to ecosystems and people.

Background information: Ocean Acidification Infographic

Table of Contents

What Are Diatoms?

How Are Diatoms Affected by Ocean Acidification?

The Importance of Diatoms

The Importance of Diatoms to the Ecosystem

The Importance of Diatoms to People

What Are Diatoms?

Diatoms are one of the two common types of phytoplankton. They are found in bodies of water such as the ocean, rivers, lakes, and ponds, as well as in mud and moist soils. Diatoms are commonly recognized by their transparent glass-like cell walls made out of silica acids (a type of mineral) that are dissolved in water. Just like corals and other marine plants, diatoms photosynthesize in order to survive, which is why sunlight and carbon are essential to their survival. Diatoms also play a vital role in transferring atmospheric carbon to the deep ocean, which helps to prevent global warming and reduce ocean acidification. 

To give you a better grasp, here is a short video explanation and microscopic footage of diatoms by MicroBiome:

How Are Diatoms Affected by Ocean Acidification?

Despite their small size, diatoms play an important role in ocean ecosystems and studies are revealing the risk ocean acidification poses to their wellbeing. Diatoms rely primarily on CO2 for their photosynthesis, so the ocean’s increased absorption of CO2 that causes ocean acidification has a large impact on the creatures. Here are some of the effects of ocean acidification on diatoms.

Ocean Acidification Could Increase the Growth of Diatoms

According to a 2019 study, high CO2 levels due to ocean acidification could increase the metabolism and growth of diatoms. This is because diatoms rely on CO2 as their source of energy in photosynthesis. However, the study’s results are still being debated and there is no final agreement on how these factors would affect the diatom community, nor how diatoms will continue to adapt to the acidifying ocean.

Ocean Acidification Slows the Development of Silica Cell Walls

ocean acidity ph scale - diatoms ocean acidification

Diatoms build their silica cell walls to protect themselves against predators such as krill. The cell wall is an important factor for their survival. According to a 2019 study published in Nature, exposure of diatoms to ocean acidification could slow their development of silica cell walls. The study reveals that even when the ocean pH level drops to 7.84 (compared to today’s pH of 8.1), the development of diatom’s silica cell walls reduces. Not only can this affect the ability of diatoms to survive, but it can create an imbalance in the ocean’s silica levels. Even small shifts in ocean acidity can have major impacts.

Ocean acidification may also impact the ability of diatoms to dissolve their shells, leading them to sink into the deep ocean. This reduces their population by making it difficult for them to get light from the surface, reducing their ability to photosynthesize to survive.

Read more: New Research Shows Unexpected Negative Impacts of Ocean Acidification on Diatoms

Ocean Acidification Could Alter the Efficiency of Diatoms’ Transport OF CO2 to the Deep Ocean

Diatoms play a big role in carbon sequestration. When they die, diatoms sink to the deep ocean with the help of their silica cell walls that serve as a weight and stabilizer. This process works to transport all the CO2 the diatoms have absorbed to the ocean’s depths, thus sequestering it in the deep ocean and removing it from the atmosphere. However, the same 2019 Nature study discussed above implies that due to the slow development of silica cell walls induced by exposure to ocean acidification, the ability of diatoms to transport CO2 to the ocean’s depths might be negatively affected. Without the carbon sequestration services of diatoms, global warming could accelerate and may cause larger ecological problems, including worsening ocean acidification.  

The Importance of Diatoms

Despite their microscopic size, diatoms play a massive global role in making marine and terrestrial ecosystems habitable for both people and wildlife. However, the threat of ocean acidification may put diatoms under new stressors that might affect the services they provide. Here are some of the ways diatoms are important to ecosystems and people.

The Importance of Diatoms to the Ecosystem

Primary Food Provider

Diatoms are at the bottom of the food chain. They serve as food to larger organisms like zooplankton, krill, algae eater fishes, snails, and more. These larger organisms flourish because of the abundance of diatoms. Even larger marine animals depend on the organisms that rely on diatoms. For example, the whale’s primary diet is krill. Without diatoms, krill would not be able to survive. If there are not enough krill to sustain the whales, it could cause starvation and ultimately decline in whale populations. 

This hypothetical breakdown of the food chain shows the importance of diatoms as the primary food source in the food chain. Any damages to diatoms caused by catastrophic events such as ocean acidification would have a significant impact on all species who rely on their services, from the smallest krill to the largest mammal on the planet.

Read more: How Are Whales Affected by Ocean Acidification?

Natural Carbon Sink 

Diatoms are considered a natural carbon sink, as they absorb up to 20 billion tons of atmospheric carbon annually. Diatoms convert atmospheric carbon into organic carbon as they absorb it through photosynthesis. When they die, they carry the stored carbon down as they sink to the ocean floor. This carbon-absorbing ability has a significant impact on mitigating global warming and climate change.

diatoms carbon cycle - diatoms ocean acidification
Diatoms carbon cycle
Source: Frontiers in Plant Science

The Importance of Diatoms to People

Major Oxygen Supplier 

Since diatoms photosynthesize, they contribute significantly to the world’s supply of oxygen. In fact, according to the most recent data, diatoms are responsible for 25% of the global oxygen supply. Without diatoms, all species that rely on oxygen, including humans, may suffer from negative health complications due to lower oxygen supply.

Supplier of Bio-Products

Diatoms not only supply oxygen but they can also be utilized in creating bio-products, products made from natural, renewable materials. According to a recent study, diatoms can produce sustainably manufactured bio-products that could be used as pharmaceuticals that benefit people. This includes the following products: 

diatoms microscopic image - diatoms ocean acidification
Microscopic view of diatoms
Source: Diatoms.org

Diatoms can help humans in a variety of ways, including those mentioned above, and there may be many more benefits that science has yet to uncover. We already know how diatoms are affected by ocean acidification, which might alter the services they provide. It is critical to guarantee that these microorganisms continue to thrive, as without them, the Earth may become uninhabitable for humans and other species.

How Are Clams Affected by Ocean Acidification?

Posted on by Team Writer

Ocean acidification occurs when the pH level of seawater decreases, which is most frequently caused by the ocean absorbing excess CO2 from the atmosphere. Ocean acidification has negative effects on a variety of ocean ecosystems and life forms, including clams.

This article will explain how clams are affected by ocean acidification, as well as the importance of clams to ecosystems, people, and the economy.

Background information: Ocean Acidification Infographic

Table of Contents

How Are Clams Affected by Ocean Acidification?

The Importance of Clams

The Importance of Clams to the Ecosystem

The Importance of Clams to People and the Economy

How Are Clams Affected by Ocean Acidification?

Clams and other shell-forming marine species are particularly vulnerable to ocean acidification. As rising acidity in seawater reduces the number of carbonate ions, shell-forming organisms like clams don’t have enough carbonate to build their shells. Here are some of the negative effects of ocean acidification on clams.

Thinner Shells 

Hard and healthy clam shells are made from the combination of carbonate ions and calcium ions (both naturally present in seawater). When ocean acidification increases, the amount of available carbonate ions decreases. As a result of ocean acidification, clams have fewer resources to develop or reconstruct their shells, causing them to become thinner over time. According to research, the thickness of clamshells significantly reduces after only 3 months of exposure to acidic seawater.

Smaller Clams

Based on the result of an experiment in 2010, juvenile clams that are exposed to acidic water don’t grow as large. In acidic water, clams have less carbonate to develop their shells, so they adjust to the low availability of their environment by using less carbonate, and thus not growing as large.

clam ocean acidification reduces size
Experiment shows how ocean acidification reduces the size of clams
Source: Global Change

Increase in Mortality Rate

The negative effects of ocean acidification on clams don’t stop at the shell’s durability and growth. According to research, clams that are exposed to ocean acidification show an increase in mortality rate after 6 months. If ocean acidification continues to rise, this will pose a serious threat to the ecological balance of marine ecosystems and the people who rely on shellfish – particularly clams, in the aquaculture industry, which covers 38% of production globally.

The Importance of Clams

Clams play an unexpectedly important role in maintaining a healthy ocean ecosystem and provide products that benefit both marine life and people. However, the increasing threat of ocean acidification puts the important services that clams provide at risk. Here are some of the ways clams are important to ecosystems and people.

The Importance of Clams to the Ecosystem

Seawater Filtration

Considered filter feeders, clams filter seawater through their respiration and feeding process. The water flows into the clam through their cilia, and all the particles that are pulled in are trapped by their gills and transferred to their mouth to feed, while the filtered seawater is released back into the ocean. This filter-feeding activity contributes to maintaining the ocean’s water quality.

Here is an example of an experiment conducted by the University of Florida/IFAS that demonstrates the efficiency of clams in water filtration:

Ocean Nitrogen Remover

Clams accumulate nitrogen by filtering water and feeding on phytoplankton, which are rich in nitrogen. When clams are removed from the ocean, nitrogen is also removed. Through shellfish culturing and farming, clams can be utilized in nutrient bioextraction, the removal of nitrogen from the seas. This can help create the right balance of nutrients in the ecosystem. Clam’s nitrogen uptake can also help bodies of water prevent excessive algae growth that often results from too much nitrogen in the water.

Natural Nutrient Cycling 

Clams cycle nutrients within an ecosystem, which help other plants and animals thrive. After digestion, clams distribute nutrients through their nitrogen-rich urine and fecal deposits that fertilize various types of marine plants such as kelp.  Other marine species such as krill, sea urchins, and crabs rely on these nitrogen-fertilized plants for food.

Carbon Sequestration

Clams are also considered a carbon sink because they utilize carbon to produce calcium carbonate to develop their shells. This contributes to the sequestration of dissolved atmospheric CO2 , which can help take carbon out of the atmosphere. This in turn can help reduce climate change and ocean acidification. 

If the ocean continues to acidify, we might lose a great number of clams and other shellfish populations. Without the services that clams provide, the ocean may face an ecological imbalance that would affect many marine species. 

The Importance of Clams to People and the Economy

How Clams Benefit Aquaculture and the Tourism Industry 

Shellfish farming, including clam farming, is very common in coastal areas. Many people that are living in these areas rely on clams as a main source of income. For example, in 2014, the clam farming sector in Washington County, Maine employed around 640 individuals. Clamming generates many economic advantages, such as clamming-related employment possibilities, the chance to expand tourism through the clam business, and tax revenue to strengthen various programs and services.

clam sanctuary and diver - clams ocean acidification
Giant clam sanctuary promoting ecotourism in the Philippines
Source: Froirivera/Wikimedia

Another example of clams’ benefits to the economy is giant clam ecotourism in Samal Island, Philippines. Today, local communities on the island, as well as resort owners, are collaborating to protect giant clam species, which increases tourism and creates new employment opportunities for seniors and women on the island. Clam tourism also generates revenue to improve community programs and services. 

With higher mortality rates, smaller sizes, and poor clam quality, the clam aquaculture and tourism sector as a whole may suffer due to ocean acidification. These negative consequences of ocean acidification on clams may harm people who rely on clams for a living, as well as the local economy that majorly depends on the clam industry.

Health Benefits from Clams in the Diet

Eating clams provides more than great flavor, as clams also provide seafood eaters with various health benefits and nutrients. Here are some examples: 

  • Clams are rich in vitamin b12, zinc, and iron, nutrients that are important in boosting the immune system.
  • Clams also provide collagen, which is important for our joints, skin, and bones. 
  • Clams contain iodine, which is important to thyroid hormone production in our body. 
  • Just like any other fish, clams are rich in omega 3 fatty acids. This fatty acid is great for maintaining a healthy heart.
  • Clams are a good source of choline. This nutrient is essential for liver protection against diseases such as the fatty liver. A study also suggests that choline could prevent or lower the risk of having Alzheimer’s disease. 
  • Clams are rich in selenium, which can increase male fertility. A study found that consuming shellfish like clams improves sperm motility.

However, research has found that clams’ exposure to ocean acidification significantly increased the amount of cobalt that clams absorb. This could be toxic to people who eat clams and may put their health at risk if the cobalt is highly concentrated. This is an indication that if ocean acidification continues, it could negatively impact not only the shellfish industry, but also human health.