Effects of Global Warming on Sea Sponges – Tipping the Balance.

Have you ever thought of the important role sea sponges play in the world’s oceans? They are in fact important members of coral reefs all over the planet.

They keep a healthy nitrogen level; this makes it available for other creatures in the reef, such as fish. Sponges are responsible for recycling the coral into sand – this ensures that the delicate balance between the growth and erosion of the reef is maintained.

Yet, the effects of global warming are threatening to disrupt this critical equilibrium. The threat is due specifically to what is known as ocean acidification and ocean surface temperature. These two factors are a result of the rise of carbon dioxide in the atmosphere and the resulting rise in the earth’s temperature.

From Coral to Sand

If you have ever seen a coral reef, its majestic beauty has very likely been captivating. Their importance to the oceans and the world can’t be overstated.

Coral reefs contain an astounding diversity of life; its surface is made of polyps (also known as stony coral), which form a living layer covering the coral.

These polyps (which are distant relatives of anemone and jellyfish) extract calcium from the water; converting it to Calcium Carbonate, which is then deposited onto the coral contributing to its growth. These limestone deposits form the supporting structure of the coral (NOAA).

Sea sponges are one of a number of creatures in the reef responsible for a process known as bioerosionEssentially, the sponge excavates the coral through crevices which have already been formed by other bioeroding organisms. The ingested limestone will be transformed into fine sand, which becomes an important part of the coral landscape. This sand eventually becomes part of tropical beaches.

This process helps to maintain the proper calcium carbonate levels – along with erosion it keep a proper balance between the building and destruction of the coral (The Journal of Experimental Biology 210, 91-96). Sea sponges are instrumental in maintaining the physical structure of coral reefs

Ocean Acidification

Naturally, carbon dioxide is crucial for life on earth. All animals and plants have a symbiotic relationship – plants need to inhale the carbon dioxide we exhale while we need to breathe in the oxygen they let out.

This gas is also important to life on earth in another way. It is the planet’s natural blanket; in the atmosphere, it prevents much of the sun’s heat from escaping back into space – which would otherwise leave the earth too cold for life as we know it.

Carbon dioxide happens to be a bi-product of much of the fossil fuels we currently burn for our every day energy needs – 30 – 40% of it is absorbed by the oceans (Earth Eclipse). This causes one of the effects of global warming – our oceans become more acidic. As a result, sea sponges, such as the Zooxanthelate Sponge in the Great Barturier Reef, increase their rate of bioerosion.

The unfortunate outcome is a coral that’s being eroded too quickly. By the year 2,100 it is predicted that coral reef erosion can increase by 2 to 4 times (Aquatic Biology). This will disrupt the balance between coral growth and bioerosion, causing havoc to the calcium carbonate budget of the coral reef.

This means the coral’s growth will be more restricted. This could be a significant disruption to the  accretion-erosion balance of the reef. With the potential to have unseen consequences for the biodiversity of the reef. Because the coral’s influence reaches the entire marine ecosystem, there will be a natural ripple effect throughout the oceans and the world as a whole.

Rise in Ocean Surface Temperature

The scientific community has been warning the public for years about the threat of rising sea levels. This ascent is made possible by the melting of polar ice and the warming of the oceans – as heat causes the water itself to expand. Ocean expansion can sink islands and speed up the erosion of shorelines – potentially displacing millions of people. The warming of the waters also lead to significant impacts below the surface.

The sea sponge depends on a symbiotic relationship between itself and the microbes that inhabit it. This relationship fails when the water temperature reaches 91.4 degrees Fahrenheit or 33 degrees Celsius (Science Alert).

By the year 2100, the oceans surface temperatures will cross this critical point on a regular basis (Science Alert). The host sponge is dependent on its relationship with the microbes for its own chemical defenses, nutrients and waste removal.

The result of this can be disastrous for the sea sponge, as it relies on the health of this relationship for its survival. The coral reef itself depends on the sponge for maintaining the proper amount of limestone, and distribution of nutrients. A disruption of this type can cause the coral to grow too slowly – if at all – causing a loss of equilibrium.

Where Are We Going

It is clear that the sea sponge is an important part of the coral reef. What affects this member of the coral community will have consequences for other creatures as well. Bioerosion keeps the coral in a healthy balance. Like all natural processes in nature, there’s a balance that has been in place for millions of years. Human activity has essentially sped up this natural process, rendering our future uncertain at best.

The experts warn us that the outcome is something we must try to avoid. Since all systems are interconnected, and we are inseparable from nature, what affects the sea sponge will have significant  consequences on us all.

What We Can Do

According to climate scientists, there are steps we can take to curb the likely consequences of global warming. Sea sponges need to be protected, as their health is intricately linked to the fitness of the entire coral reef. One of the important roles they provide is called bioerosion; which regulates the growth of the coral by converting the calcium carbonate limestone to fine sand.

This process is being accelerated by the acidification of the oceans, which are absorbing the excess carbon dioxide from the atmosphere. This surplus is the result of burning of fossil fuels; which is also warming up our planet – including our oceans.

This ascent in water temperature is hindering the sea sponge’s symbiotic relationship with the microorganisms that inhabit it.

If we can transform how we meet our energy needs, then our sea sponges, and thus our coral reefs, will have a better chance – which also means our outlook will fare much better as well.



What do you think about our impact on the world’s Sea Sponges? How important do you think they are? What do you think we can do to protect them? Please leave a comment!




Thanks for stopping by,














  1. After watching Planet Earth I have a whole new appreciation for coral reef (and our planet in general!) However, I didn’t know that the coral turns limescale into sans. That is truly fascinating. I always thought that sand was from the bottom of the ocean.

    Practically speaking what can we do to protect these sea sponges? Is recycling and looking after our oceans not enough?

    • Hello Hollie Rose! You’re right, corals are both beautiful and incredibly important. They’re in effect the canary of the ocean. They provide a home to countless fish that are born there and then travel to the open sea where they provide food for millions of people around the world. Corals also protect our coasts by preventing storm surges from destroying our coasts. 

      What threatens sponges is both rise in ocean temperatures and ocean acidification. Ocean temperatures increase by the effects of too much carbon dioxide in the atmosphere  – while ocean acidification is the result of the absorption of excess carbon dioxide in the atmosphere. Carbon dioxide is the result of burning fossil fuels like oil and gasoline. 

      We are part of this planet – what ever affects it will affect us. 

      Thank you – 


  2. I think that this is a great article Jose. Sea corals are very important for our nature and I agree that we should do everything to protect them but also other beings that mother nature gave us. I am only afraid that global warming will continue to grow and that other animals will suffer.

    • Hello Daniel, Absolutely! Corals are incredibly important to the health of our oceans. They are the nurseries to many of the fish that provide food for millions of people around world. They also act as barriers against storm surges that would other wise destroy coastlines. 

      We must  do everything we can to protect the sponges; they are a central piece of the coral and its well-being. Sponges have been around for 600 million years – the most successful animal ever. We can learn a lot from them. 

      Take care


  3. I have to agree that we need to take a LOT more steps to save the sea sponges.  I did not realize they had such a vital role.  I think too, that we should be working a lot more towards using alternative energy sources (natural).  For instance in homes where the sun shines daily (like here in Florida), why are they not automatically installed in the new homes.  Seems like we can be doing so much more.  I do the best I can recycling and reusing, but it is just a drop in the bucket.

    • Hey  Matt’s Mon! I was also unaware until I chose this niche. Sea sponges and freshwater sponges are critical for our environment. They  have been around for 600 million years – making them the most successful animal ever. They absolutely play a vital role in our oceans – converting coral into fine sand to shape the landscape of the reef, controlling the nitrogen cycle and as a result providing vital nitrogen to many coral reef inhabitants. 

      Yes, we should create our lives to be in harmony with nature. Thank you for caring and for what you do for our home and our children’s future. 

      Take care..


  4. I always worry so much when it comes to what’s happening all over the world, but especially in the oceans. Sea sponges are an important part of the biodiversity, as you mentioned. So is everything in there! 

    I not only worry about global warming and what that’s doing, but also overfishing and pollution. There is so much plastic in the oceans! I know that’s not good for anyone, including the sea sponge. I really hope we can get it together before it’s too late…

    • Hello Christina! Our oceans are more important than most people realize. The sea sponge is a central citizen of the coral reefs; the reason being that they control the growth of the coral and control the nitrogen cycle – providing nitrogen to many of its inhabitants.  I’m glad for people like you who care for our planet and the gifts it holds for all of us. Maybe if we can stop fighting over it, then maybe we can really enjoy it

Leave a Reply

Your email address will not be published. Required fields are marked *