How Do Sea Sponges Help The Environment?

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Sea Sponges that belong to Phylum Porifera are very much important to the environment. Not only environmental importance but the sponges also do have a lot of biological, economical, and medicinal importance as well.

Sponges just like the corals, seem like non-living creatures but, they are living organisms.

Sponges are very small, delicate (very fine in texture or structure), sessile (fixed at one place), branching, colonial, and marine poriferas that possess the cellular level of body organization.

Sponges help in maintaining the environment in an all-new set of ways. They are the benthic level organisms that are very important in the various nutrient cycling steps. They are also natural water-purifiers, coral biodiversity maintainers, protection and food source for other small fishes, worms, etc.

They do also help the environment by supporting the marine food web while encouraging the growth of commercially important species of deep-sea biodiversity.

Here in this post we will discuss in a lot more detail about the contribution of Sea Sponges and also how they help the environment.

Sponges in Caribbean Sea, Cayman Islands
Sponges in Caribbean Sea, Cayman Islands

How Do Sea Sponges Help The Environment? Let’s Know About It:

They support the marine food web

The food web that is managed by the sponges is the relation of the energy that is passed between the benthic and the pelagic communities of the marine environment in a very simpler form.


There are various other materials that get attached and start to accumulate at the base of the sponge. These accumulating materials attract various other sessile organisms such as Cnidarian colonies, etc.

Sponges are holobiont in nature meaning that they stay in assemblage with many other species like microorganisms, cnidarians, crustaceans, etc. living in or around it, which together form a discrete ecological unit.

Sponges get their food by the filter-feeding mechanism. It’s how a sponge filters out plankton or nutrients suspended in the water.

The symbiotic microorganisms associated with the sponges also help in the availability of food for the sponges.

These sponges are eaten by many other larger animals like jellyfishes, crustaceans, fishes, starfishes, turtles, tortoise, etc. As they feed on the sponges, the energy is passed to the next trophic level.

In this way, the energy flows in the various food chains and altogether in the food web.

The sponges highly contribute a lot to the transfer of energy from benthic to the pelagic communities which is actually very essential for thriving the ocean environment and ecosystem.

They act as natural water-purifiers

Spongers are very much important for the environment. They help in making the marine ecosystem pollution-free.

Sponges can remove up to 95% of bacteria and polluting/non-polluting particles from the water (POM) and 90% of dissolved organic carbon (DOC), thereby converting suspended particles and dissolved matter into food for other animals.

The water canal system in sponges invariably filter a large volume of seawater and potentially accumulate heavy metals and other contaminants from the environment. This makes the water free from oil, polluting microorganisms, etc. as well.

The sponges have the capability to accumulate anthropogenic pollutants such as metals, sewage, industrial effluent, pesticides, fertilizers, etc. over a long period in their body. Thus, leading to very less pollution in the oceans.

Ocean sponges have incredible filtering power. Their filter-feeding mechanism of the canal water system helps in straining the water around them to capture organic debris particles and other microscopic life forms.

So, that’s why sponges are also used as indicators of heavy marine pollution as well.

They maintain the coral reef biodiversity

Sponges are really larger and some are even massive than the corals. They are huge participants in the coral reef ecosystem by providing habitat, food, and safety to the various other small-sized organisms of that ecosystem.

The sponges maintain the coral reef biodiversity primarily by recycling vast amounts of organic matter to feed snails, crabs, and other creatures.

Sponges recycle nearly ten times more matter than what the bacteria do, and they do also produce as much nutrition that all the corals and algae can combinely provide.

Their filter-feeding canal system mechanism helps as a water-purifier by removing harmful pollutants from the water. This leads to more increase in the marine biodiversity in the deep sea coral ecosystem.

Sponges do also serve as secure houses for several crustaceans worms, molluscs, small fishes, etc. which seek protection in them against the predators.

Some species also make the location in and around the sponges as nursery and breeding grounds.

They do also take part in the energy flow of the food web. Sponges when consumed by cnidarians or by other larger organisms like snails and crabs, smaller fishes help in the transfer of energy form the benthic to the pelagic communities.

They are also a good source of food for many sponge-eating fish species. Moreover, the organisms living inside the sponges also get food easily due to the presence of the water canal system in the sponges.

They take part in Carbon cycle

The sponges take part in the carbon cycle and bring the ocean dissolved carbon into the bodies of the marine animals.

The major forms of C in marine biogeochemical cycles are inorganic C in the form of bicarbonate. carbon dioxide (CO2), and total organic carbon (TOC). TOC is comprised of dissolved organic carbon (DOC) and particulate organic carbon (POC).

Sponges get their C availability from POC (particulate organic carbon), DOC (dissolved organic carbon), or inorganic C fixation by photosynthetic symbionts.

Sponges can quickly deplete POC and DOC in the surrounding water, by way of heterotrophic feeding.

The largest quantities of DOC in the coral reef ecosystem are obtained from the algae and corals respectively. POC accounts for only a small proportion of sponge respiration and growth requirements.

Marine algae release DOC as a photosynthetic byproduct while the corals release DOC in the form of mucus. On the other case, most POC acquired by the sponges was from non-photosynthetic symbiotic bacterial cells.

Overall, there is a great diversity of processes through which the sponges can obtain C. That’s how carbon is taken by the sponges and when the sponges are eaten by other organisms carbon is passed to the next step of the cycle.

They take part in Sulfur cycle

Sulfur cycle is possible by the sponges in those places where high concentrations of sulfate (SO42−) in seawater is present along with the presence of sulfonated polysaccharides and lipids in the sponge extracellular matrix of the sponge species.

Sulfur oxidizing bacteria (SOB) like Spongiobacter, etc. stay in close association with the sulfur absorbing sponges. These bacteria are generally obligate or facultative autotrophs that can either use carbon dioxide or organic compounds as a source of carbon.

Sulfate-reducing bacteria (SRB) have also been found in many sponges. They do help in SO42− reduction in sponges in the deep ocean ecosystem.

In sponges, S oxidation, S reduction, and various coupling reactions between these processes take place in combinations that allow the sponges and the specialized symbionts to fix sulfur from the surrounding water.

They take part in Nitrogen cycle

Nitrogen cycle steps like the N fixation, nitrification, denitrification, and anaerobic ammonia oxidation are all have been well-detected in sponges.

Genetically it is also seen that N cycling genes are well present in the actual metagenome of the various sponge species studied so far.

It is seen that sponges can act as both a source and a sink of bioavailable N to both their symbionts and the surrounding reef ecosystem.

In N fixation, atmospheric nitrogen (N2) can be fixed into ammonia (NH3) by sponge bacterial symbionts with the presence of the Nitrogenase enzyme. This process requires anaerobic conditions and O2, NH3, and H2S are some of the major factors that affect N fixation.

Then Nitrification occurs, which is actually the aerobic oxidation of NH3 into NO2 and subsequently into NO3. The NH3 is supplied either by N fixation or the remineralization of POM (particulate organic matter).

Nitrification has been shown to be nearly ubiquitous within the sponge population regardless of microbial abundance.

It is also to be noted that, within the sponge body, nitrification and N fixation are tightly coupled with denitrification and anammox as the former processes provide the substrates (NH3, NO2, and NO3) for the latter.

Sponges thus help in the Nitrogen cycle of the marine environment. Sponges can act as a source of NH3 for their associated prokaryotic community and also as a source of NH3 and NO3 for the surrounding reef environment.

They also take part in Phosphorus cycle

Sponges are very important recyclers of Phosphorus in coral reef communities. They efficiently take part in the Phosphorus cycle of the marine ecosystem.

In the marine environment, P is available in both dissolved and particulate forms.

P in such an environment is also highly transformed between a variety of inorganic and organic forms through microbially mediated mechanisms.

One such form is the Polyphosphate (polyP) form, which is a multi-chained linear or circular compound comprised of tens to hundreds of phosphate (PO43−) molecules.

Polyphosphate (polyP) is present in almost all organisms as a major energy storage compound. In sponges too, it is found in abundance.

The role of polyP within sponges and their symbionts is very significant. Sponges do also have various calcium-phosphate minerals in their body making them P sinks.

In sponges, water flowing through the mesohyl (mesenchyme) gelatinous matrix facilitates a redox gradient suitable for both polyP accumulation and degradation.

It is seen that when mesohyl is oxygenated the bacterial symbionts can store phosphate as polyP, and when the oxygen levels drop it leads to polyP degradation and Pi release into the surrounding environment.

That’s how the phosphorus cycle is carried out by the sponges. Sponges may act as either a sink or a source of P, and their primary role in P biogeochemistry is not yet clear.

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