Environmental Impacts


Though the oceans are Earth’s largest ecosystem, covering more than two-thirds of the planet’s surface and hosting 80% of the its biodiversity1, more than 99% of that area is extremely sparsely populated with life—on par with tundras and deserts on land.2 Rather, marine life is concentrated in coral reefs and algae beds, roughly 0.1% of the planet’s surface.3

Tiny marine invertebrates called coral extract calcium carbonate from seawater to build themselves a hard exoskeleton around their soft bodies. These hermatypic, or “hard”, corals accumulate in large colonies and continue to thrive atop the skeletons of their ancestors. Over time, these mounds of coral skeletons grow into massive underwater structures, providing safe harbor for huge volumes of sea life.4

Coral reefs are the “cities” of the marine ecosystem: home to more than 25% of all marine species, frequent feeding grounds to countless others, and indirectly supporting all ocean life by functioning as hubs for productivity. Compared to the biologically unproductive open ocean, coral reefs can sustainably produce 5-15 tons of fish, crustaceans, mollusks, and other invertebrates per square kilometer per year.5

Today, the majority of Earth’s substantially-sized coral reefs are 5,000 to 10,000 years old.6 To sustain this long-term growth, coral reefs accumulate calcium carbonate faster than erosion wears them down.7

Moreover, coral reefs are essential tourist attractions, contributing more than 30% of export earnings in more than 20 tropical countries. In the warm, clear, shallow waters of the Caribbean, where coral reefs are the visitor’s destination of choice, tourism accounts for a quarter of the total economy and one-fifth of all jobs.8


But coral reefs are in rapid decline worldwide due in large part to ocean acidification.9 A quarter of the atmospheric carbon dioxide commonly associated with global warming is absorbed by the world’s oceans, causing a measurable decline in the water’s pH. In the lower pH conditions, coral stop working (they abandon their symbiotic relationship with the colored algae living in their tissues consequently turning white, or “bleaching”) and, eventually, die.10 The prospects for coral reef and the marine life dependent upon them are dire. For example, off the coast of Australia, a bleaching of Great Barrier Reef between 2016 and 2017 killed off 50% of its corals.11


Sea cucumbers are the “earthworms of the sea”–they recycle nutrients by combing through the sand, breaking down organic matter for bacteria. This is important because when too much organic matter builds up, algae growth spirals out of control, forming what’s known as a bloom. Algae blooms gobble up all the available oxygen as they die and decompose, choking out other wildlife. A 2012 study confirmed that sea cucumbers are essential to preventing this from happening.12

Similarly, a 2010 study confirmed the essential role of sea cucumbers in maintaining healthy organic matter balance in seabeds—where sea cucumber numbers are declining, sea grass is dying.13

But sea cucumbers’ ecological relationship with coral is particularly important: sea cucumbers release the calcium carbonate essential for coral growth into the sea water and sea cucumbers’ digestive processes increase the water’s pH, counteracting the acidification largely responsible for recent coral reef decline. A 2012 study confirmed that “sea cucumbers play a vital role in reducing the harmful impact of ocean acidification on coral growth.”14

More studies are required to determine how much positive impact can be gained by seeding coral reefs with sea cucumbers, but research has already identified the crucial role sea cucumbers can play in mitigating the impact of global warming on coral reefs. On the flip side, a 2018 study confirmed that the removal of sea cucumbers significantly decreases coral reef’s ability to endure organic matter inputs from rainfall and flooding inland.15


Sea cucumbers are a delicacy in many parts of Asia, commanding surprisingly high market prices in the hundreds, or even thousands, of dollars per kilogram, and increasing every year. Consequently, sea cucumber populations have been devastated worldwide despite official bans on collection and export.16 On top of that, since sea cucumbers reproduce through external spawning, if the density of a local population drops too low, they won’t be successful in recovering their numbers and will go extinct.17 The sea cucumber over-fishing epidemic has led to the International Union for Conservation of Nature, charged with identifying threatened species worldwide, adding 16 species of sea cucumbers to its list.18


Aquaculture production of sea cucumbers, as opposed to wild harvesting, involves breeding and farming them in a controlled area. When the growing area is a sheltered ocean bay, as opposed to land-locked pools, the numerous environmental benefits provided by sea cucumbers are conveyed to the local marine ecosystem. Sea ranching, as this method is called, allows for the cultivation of sea cucumbers as valuable food product while simultaneously improving the marine habitat by cleaning the sea floor of surplus organic detritus, preventing and consuming unhealthy algae blooms, distributing ammonia to fertilize other sea life and the calcium essential for coral, and combating the acidifying effects of climate change.

1 – 7 reasons why we need to act now to #SaveOurOcean, March 2017, http://www.fao.org/zhc/detail-events/en/c/846698/

2 – Oceans are Deserts, February 2019, https://www.youtube.com/watch?v=MT28gm9CNuI

3 – Coral Reef Alliance – Reef Threats, June 2019, https://coral.org/coral-reefs-101/reef-threats/

4 – Live Science – What Are Coral Reefs? – September 2018, https://www.livescience.com/40276-coral-reefs.html

5 – Coral Guardian – Saving Marine Ecosystem, June 2019, https://www.coralguardian.org/en/marine-ecosystem/

6 – Coral Reef Alliance – How Coral Reefs Grow, June 2019, https://coral.org/coral-reefs-101/coral-reef-ecology/how-coral-reefs-grow/

7 –  Coral bleaching and ocean acidification are two climate-related impacts to coral reefs, June 2019, https://floridakeys.noaa.gov/corals/climatethreat.html

8 – The New GESAMP – Science for Sustainable Oceans, 2005, http://www.gesamp.org/site/assets/files/1256/newgesamp.pdf

9 – Ocean acidification causes bleaching and productivity loss in coral reef builders, November 2008, https://www.pnas.org/content/105/45/17442.long

10 – Reversal of ocean acidification enhances net coral reef calcification, March 2016, https://www.nature.com/articles/nature17155

11 – International Union for Conservation of Nature – Coral reefs and climate change, June 2019, https://www.iucn.org/resources/issues-briefs/coral-reefs-and-climate-change

12 – Deposit-Feeding Sea Cucumbers Enhance Mineralization and Nutrient Cycling in Organically-Enriched Coastal Sediments, November 2012, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0050031

13 – The ecological role of Holothuria scabra (Echinodermata: Holothuroidea) within subtropical seagrass beds, July 2009, https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/ecological-role-of-holothuria-scabra-echinodermata-holothuroidea-within-subtropical-seagrass-beds/EBF47A4A1EEEAE013F33AF9C6A177DE5

14 – Sea Cucumbers Counter Negative Effects of Ocean Acidification, February 2012, https://scitechdaily.com/sea-cucumbers-counter-negative-effects-of-ocean-acidification/

15 – Study in Fiji finds that removing sea cucumbers spells trouble for shallow coastal waters, June 2018, https://www.sciencedaily.com/releases/2018/06/180605172500.htm

16 – These Bizarre Sea Creatures May Help Save Coral Reefs—If They Survive, February 2018, https://news.nationalgeographic.com/2018/02/wildlife-watch-sea-cucumbers-illegal-wildlife-trade-coral-reefs/

17 – The Sea Cucumber’s Vanishing Act, March 2016, https://www.hakaimagazine.com/features/sea-cucumbers-vanishing-act/

18 – These Bizarre Sea Creatures May Help Save Coral Reefs—If They Survive, February 2018, https://news.nationalgeographic.com/2018/02/wildlife-watch-sea-cucumbers-illegal-wildlife-trade-coral-reefs/