What does Dugongs’ extinction in China mean for its relatives in India? 

Dugongs, vegetarian marine mammals are now officially extinct in the Chinese waters. This piece explores the significance of its existence and extinction and what does this mean to the endangered species’ relatives in India’s Palk Strait?

Dugongs, popularly known as ‘Sea Cows,’ are the only surviving species of aquatic herbivores that belong to the order Sirenia of the Dugongidae family. Unfortunately, they are highly vulnerable to extinction and one among the critically endangered species of the International Union for Conservation of Nature (IUCN). They are positioned on the IUCN’s Red List of threatened species and are hunted to extinction for their precious meat and oil. But why are we discussing dugongs now? That is because these benthic seagrass creatures are officially declared functionally extinct on the Chinese coastline after a recent study in August 2022.

The dugong population in China has been reducing rapidly since the 1970s, primarily due to human-caused problems that led to habitat loss of the species. Besides, the study highlights some major reasons for dugong extinction in the region: overfishing and ship strikes. To understand the dugong population in the region, about 800 fishermen reportedly scattered across the South China Sea were interviewed. Of which only three respondents answered they had sighted dugongs over the last five years at the site. Another substantial piece of evidence that proves dugong’s extinction is the absence of any official field observation record of dugong sightings after 2000. The reason behind dugong extinction is that the area receives massive stress from the fishing industry for housing some of the rarest and the most spectacular marine biodiversity in the world. Hence, these marine species are hunted for their delicious meat. Another important reason for dugong extinction is bottom trawling, one of the most prominent fishing methods in today’s era. This destructive method uses a large net with a wide mouth and a small closure to catch a large quantity of fish. As bottom trawling is indiscriminate with its catches, it destroys the seabeds uprooting innumerable plants, thus, sweeping off natural habitats of dozens of aquatic animals in these nets.

Image 1: A representative image of a dugong Pic: 2g601hto8u_Medium_WW1221.jpg

Nevertheless, what does this mean to the remaining dugongs on India’s coastlines? India is a country known for its rich biodiversity. Since 1983, India has been a non-legal MoU signatory of the Convention on the Conservation of Migratory Species of Wild Animals (CMS) for various species such as Sea turtles, Dugongs, Raptors, and Siberian Cranes. According to the Wildlife Institution of India, there are about 200-250 dugongs in Indian waters, of which 75 are found in Andamans and 150 in the Palk Bay in the Gulf of Mannar. Therefore, in 2021, the Tamil Nadu government initiated the idea of establishing India’s first Dugong conservation reserve in the Gulf of Mannar in the Palk Strait Bay. Consequently, the state government allocated an area ranging around 500 sq. km in the Palk Bay and the Gulf of Mannar biosphere reserve to protect the fragile and stunning biodiversity of the region. In addition, the area houses some rare fishes, sea turtles, and seahorses. The reserve stretches from Adirampattinam in Thanjavur district to Amapattinam, a coastal neighbourhood in Pudukottai district.

But why are Dugongs significant to the marine ecosystem? Dugongs play a crucial role in balancing marine ecosystems. Since these vegetarian marine mammals feed on underwater seagrass, their repeated action promotes the regrowth of plant species. The availability of seagrass will also affect the existence of other sea creatures, such as dolphins, turtles, etc., which also depend on seagrass as a primary food source. Thus, the extinction of dugongs from Chinese waters is an alarming indication to speed up conservation efforts. India’s first dugong conservation reserve in the Gulf of Mannar is a stepping stone in the path of effectively planned conservation.

References

Chaitanya, K. S. V. (2021, September 4). India’s 1st dugong conservation reserve to be in Tamil Nadu. . . The New Indian Express. https://www.newindianexpress.com/states/tamil-nadu/2021/sep/04/indias-1st-dugong-conservation-reserve-to-be-in-tn-2354056.html

Shaji, K. A. (2022, January 16). India’s first dugong reserve will help protect the world’s only herbivorous marine mammal. Scroll.In. https://scroll.in/article/1014882/indias-first-dugong-reserve-will-help-protect-the-worlds-only-herbivorous-marine-mammal

Ives, M. (2022, August 27). The Dugong ‘Sea Cow’ Has Vanished from China’s Waters, Study Says. The New York Times. https://www.nytimes.com/2022/08/26/science/china-dugong-sea-cow-extinct.html

Tidal Energy: A Boon or Bane?

As the demand for clean energy is increasing by the day, various entities are eyeing the renewables. Though wind and solar are already on the run, the race for tidal energy is yet to begin.

Powered by the kinetic energy from the natural rise and fall of ocean currents and tides, tidal energy is a renewable source of energy that is primarily used to generate electricity. It is caused by the gravitational attraction between earth, moon, and sun, thus producing tidal forces. As the earth rotates, these forces correspond to the movements leading to a changing ocean currents’ motion. As a result, tides are stable and predictable and can produce a steady stream of electricity. Therefore, owing to its infinite capacity, it is often considered an inexhaustible renewable energy source for the future.

Image 1: A representative of tidal stream generators. Pic: tidal-energy.jpg

But tidal energy extraction gained momentum only in the early 20th century. In the early 1920s, US and Canada conducted many state-sponsored studies to understand the tidal force’s potential to replace non-renewable energy resources and the developmental costs for the same. Despite being widely accepted as a potential renewable energy source, the amount of power produced from tidal force has been minimal. Even today, there are very few commercial tidal power plants operating worldwide. As tidal energy is relatively new, there are no multiple power-generating techniques to extract tidal energy; nevertheless, there is a prominent use of special energy generators to convert tidal force into electricity. Currently, there are three known methods of tidal energy generation. These include Tidal Turbines, Tidal Barrage, and Tidal Lagoon.

Turbine: A turbine takes energy from flowing fluid; this fluid could be wind or water. A wind turbine converts kinetic energy into electrical energy to generate power from a windmill. Similarly, as tides are fast-flowing waves of water, turbines are placed to capture the kinetic energy of the moving water. As tides are denser than winds, tidal energy produced is more powerful than wind energy. While turbines can operate at any depth, it is best to position them in shallow water. Tidal stream generators use breeze turbines placed in clusters under the water to generate power from underwater currents. Besides, stream generators also include float turbines. These turbines are anchored to the seafloor using cables, and energy is produced from the turbines that rotate due to the water stream movement. As tidal turbine blades are slow in their motion, it is less likely to affect marine biodiversity. However, local conditions and the turbine size are significant in determining the impact of tidal generators. In addition, turbines are large and disrupt the motion of tides and currents; therefore, it becomes difficult for the machines to capture and harness the energy.

Barrage: Barrages are dam-like structures built across rivers or ocean bays for generating power using potential energy. The turbines inside the barrage take advantage of the differences between the high and low tides. Water from the high tide is released through the turbine, generating electricity. The water level changes in the area surrounding a barrage, which changes the water salinity of the region around the barrage. These changing ecosystem conditions might harm the organisms that live in the water body. In the case of a barrage, a cluster of turbines is placed horizontally; with the fast movement of the blades, there is a high likelihood of marine life getting caught in the quick action resulting in injury or loss of life. Consequently, the sea birds in the region whose primary feed is based on fish may migrate as their food source is limited.

Image 2: A representative image of a tidal barrage. Pic: tidal-power-plant.jpg

Tidal Lagoon: Lagoons are large water structures created by reservoirs similar to tidal barrages and seem like separate bodies of water away from the tides. Lagoons are usually constructed alongside natural coastlines. They appear like a seawall at low tides, submerged at high tides, and are enclosed by a human-made or natural barrier. Accelerating turbines attached to the sea walls generate power from the tidal streams. Lagoon power generation involves extracting electricity from the tide when it comes in and goes out. Though the energy produced from a lagoon is considered more eco-friendly than that produced in a barrage, they are less environmentally damaging. This is because lagoons are smaller in size, and due to their size, small fishes thrive in a lagoon, which may attract birds that prey on marine life.

Regardless of the methods and technologies, why is tidal energy still at the start point in the run for renewability and sustainability while wind, solar and nuclear are on their paths to accomplishing their mark? Despite being a clean energy source, why is tidal energy not as popular as the others? Why are only a few industrial units producing tidal energy on a broader scale? It is crucial to find answers to these questions to understand the potential for the large-scale production of this alternative form of energy. Though it is not enough to suffice everyone’s energy demands, it plays a key role in reducing our reliance on fossil fuels and non-renewable energy sources. These projects can be horrific to local communities such as coastal communities involved in marine livelihoods in cases of community displacement. Hence, numerous studies have been conducted to understand the socio-ecological impact of tidal energy.

Most studies show that the environmental consequences are site-specific based on local geography and ecology. Tidal range projects like the barrages are enormous stress on the local environment; these projects alter the water levels, reducing the population of migratory fish in the ecosystem. These projects are located in sites with high tides that generate energy based on high and low tide differences, such as in Canada, South Korea, Russia, China, New Zealand, etc. Furthermore, electricity is generated when the temporarily stored tidal water flows through the turbines, which on fast movement, have the potential to injure or kill marine plants and animals, thereby affecting the bird population that depends on these sea creatures as a source of food. Additionally, as tidal energy equipment is often placed near the shore, there is a possibility that the electromagnetic fields and acoustics may affect marine organizations in the region. Moreover, as these equipment are placed offshore, the soil around the region is also disturbed. Developments in tidal energies are still in their beginning phase; hence, the disposal process of used/old equipment and technologies utilized in energy extraction is not widely discussed. However, newer technologies are being introduced to balance out these negative implications.

One of the reasons why tidal energy is not very prominent is that it is not cost-effective during the initial stages of establishment. Especially, tidal barrages are costlier than the other methods owing to the money involved in constructing dams/reservoirs. Therefore, tidal energy is more expensive than other renewable energies, yet the net energy produced from tides is minimal. Another reason is that the research and developments in the field are still in their infancy stage, so investing in the resource does not guarantee a return. Therefore, given the financial constraints, only developed countries in the Global North are developing tidal energy projects.

These claims show that the current possibilities for full-fledged use of tidal energy resources are pretty bleak. Thus, in conclusion, the takers for tidal energy are divided.

References

National Geographic. (n.d.). tidal energy | National Geographic Society. https://education.nationalgeographic.org/resource/tidal-energy/

The potential of tidal energy production. (2015, August 30). GreenFacts. https://www.greenfacts.org/en/tidal-energy/index.htm#1

Into the Depths of the Indian Ocean

The Indian ocean being the world’s third biggest ocean covering 7,05,60,000 sq km which is 19.5% of Earth’s water surface and 19.8% of the global ocean volume is the least understood ocean among the 5 oceans with complex geomorphology. The Indian ocean has subduction trenches, seamounts, ridges, plateaus, coral atolls, fracture zones and hydrothermal vents but is scientifically neglected for years.

The Java trench is the deepest subduction trench in the Indian ocean and also the only trench which exceeds the hadal zone (more than 6000m water depth). Java trench is also called Sunda trench which is 2000m long and 7290m deep. As a part of the Pacific ring of fire, the Java trench starts from the Lesser Sunda Islands past Java, around the southern coast of Sumatra on to the Andaman Islands, and forms the boundary between Indo-Australian Plate and Eurasian plate.

The study on Java trench is recent and because of its depth this trench has an isolated geographical hadal ecosystem. It has a temperature of 1.54°C with fine grained sediment plateaus. The Java trench has 10 phyla, 21 classes, 34 orders and 55 families. There are 36 chemosynthetic bacteria mat deposits of orange, yellow, and white in color. The trench is populated by hexactinellid sponges. Holothurians like Amperima cf. naresi, Elpidia cf. sundensis, Enypniastes sp., Psychropotes sp., Elpidia cf. sundensis, Munnopsid isopod. Actiniarias like Galatheanthemum and Bathyphellia, Snailfish, Echinoderms like the asteroid Hymenaster sp., unidentified Ophiuroid sp., fragile, semi-transparent Crinoids, unidentified crinoid, and unidentified Ophiuroid sp., the polynoid polychaete, Macellicephaloides. Amphipods like the supergiant Alicella gigantea, Bathycallisoma schellenbergi, the unidentified Stegocephalidae species, and the pardaliscid Princaxelia, the Mysid Amblyops sp., the stalked ascidian, Culeolus sp, echinoderms like ophiuroids or brittle stars (Ophiuroidea), asteroids or sea stars (Asteroidea), and crinoids or feather stars (Crinoidea), 98 unidentified ophiuroids (Ophiuroid sp. 1), Anemone Galatheanthemum, Anemone Bathyphellia, Polynoidae Macellicephaloides, mysid Amblyops sp., Alicella gigantea, Princaxelia, Bathycallisoma schellenbergi, Stegocephalidae sp,. Grimpoteuthis sp., larvaceans, 7 Ophidiidae species, 1 Ateleopodidae species and 1 liparid species are discovered in the deepest point of the Indian ocean. The Java trench is still highly unexplored and has undiscovered and undescribed life forms.

Inside the least studied ocean within the least explored trench with many unidentified species, plastic and man made metal items were found proving that there is no “pristine” wilderness left neither on land nor in the deep oceans.

References:
https://www.frontiersin.org/articles/10.3389/fmars.2022.856992/full?&utm_source=Email_to_aut
hors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication
&field=&journalName=Frontiers_in_Marine_Science&id=856992
https://en.wikipedia.org/wiki/Sunda_Trench
https://www.britannica.com/place/Java-Trench

Kerguelen Plateau and Its Implications for Climate Change

The Kerguelen Plateau is located in the Indian Ocean, and is the longest continually erupting supervolcano. From 90 to 120 million years ago, basaltic lava eruptions from fissures on the seabed led to the formation of a volcanic plateau that eventually rose above the sea level. The presence of soil layers and charcoal from previous vegetation in the basalt indicates that the Kerguelen Plateau was once above sea level. Due to the volcanic rock sinking slowly, the Kerguelen Plateau is currently oceanic, 1000-2000m below the sea level. The Kerguelen Islands, (French territory) and the Heard and McDonald Islands (Australian territory), are the only parts of the plateau that remain above the sea level (Bressan, 2020).

The Kerguelen Plateau is classified as a Large Igneous Province (LIP). LIPs are formed as a result of massive volcanic events. They are formed due to the accumulation of basalt and volcanic rocks. LIPs can form on existing continents, in the ocean or at tectonic plate boundaries (Coffin, 1994). The Kerguelen Plateau has an area of 1250000 sq km. To put things in perspective, its area can be compared to half the size of the Australian continent.

Location

The plateau is situated in the temperate zone of the Southern Hemisphere. It is a part of the sub-Antarctic shelf (Barnes et al., 2018). On the map, it can be found between Africa and Australia, towards the south of both continents.

Why is there volcanic activity even today?

The unique geological features of Kerguelen Plateau make it conducive for volcanic activity. The edges of three large tectonic plates are found in the Indian ocean – the African, the Antarctic and the Australian plates. The Kerguelen Plateau was initially located in between the Antarctic and Australian plates, which was a hot-spot of volcanic activity. This provided the heat needed to melt the rocks and the magma spread along the ridge between the tectonic plates. The magma cooled and solidified to form the plateau.

The Kerguelen Plateau drifted towards the south across millions of years, moving away from the volcanic hotspot. Thus, though it is still volcanically active due to its location, the frequency of these eruptions has decreased (Bressan, 2020).

Kerguelen ecosystem

The ecosystem comprising the plateau, Kerguelen islands and the Heard and McDonald Islands are isolated from the mainstream human settlements. The plateau is home to rich biodiversity. It supports the growth of these species as the mineral content from the volcanic eruptions make the region nutritious.

The plateau is home to a rare and expensive variety of fish called the Patagonian toothfish. It is also called the Chilean seabass, sold in the market at high prices. The white flesh of these fish is considered as a delicacy and is said to be healthy. The toothfish populations are vulnerable to unsustainable fishing and illegal poaching (Dell, 2019).

Since the toothfish is a top predator, it has ecological importance in balancing the population of other marine species it feeds on, maintaining the food chain and structure of the ecological community.

The banks of the plateau are inhabited by coral species, crustaceans, sponges and anemones. They are slow growing communities, and ecologically sensitive to anthropogenic disturbances.

The plateau intercepts the strong water currents around the south pole. There is an upwelling of cold water from the depths of the sea with volcanic minerals to the surface, which again returns to the bottom. This nutrient transport supports diverse marine life and a food cycle from zooplankton to penguins, albatross, elephant seals and sperm whales. The seabed supports invertebrates and fish species that are only present due to the nutrients from the plateau (Dell, 2019). 

Implication for climate change

Ocean currents from the tropical deep-sea carry nutrients towards the Arctic and Antarctic regions. There are no primary producers at the poles because phytoplankton (consumed by small organisms which are then consumed by the predators) do not survive in the frigid temperatures. So, the nutrients are transported back to the tropical regions by the currents.

In the case of global warming, the poles receive more sunlight because of the melting glaciers. The warming conditions allow for phytoplankton to grow. Therefore, the polar regions and the surrounding oceanic environment will utilize more nutrients and support marine species that migrate to cooler, polar waters.

The location of the Kerguelen Plateau close to the south pole makes it important for scientists to understand the pole-ward shift of marine organisms due to climate change (Dell, 2019). The plateau is being studied to understand how this change will impact oceanic ecosystems near the equator and vulnerable species.

Blue carbon sequestration

Blue carbon sequestration refers to the carbon removed from the atmosphere and stored in coastal and marine ecosystems.

Snowmelt in the polar region results in increased phytoplankton bloom due to the sudden increase in sunlight and heat. This increases the carbon sequestration abilities of the region, which is negative feedback on climate change (i.e., slows the rate of global warming by capturing atmospheric carbon near the poles) (Barnes et al. 2018).

Research shows that the Kerguelen Plateau has potential for blue carbon sequestration in the future while supporting marine biodiversity. There was an increase in organisms at the Kerguelen region across the past decade, suggesting that carbon storage would have also increased (Bax et al., n.d).

Conclusion

Oceans are carbon sinks – dead marine organisms are decomposed and the carbon is sequestered at the seabed. Phytoplankton at the surface of the water uptake carbon for their growth.

The Kerguelen Plateau’s features and location could help provide a better understanding of marine ecology and the changes caused by climate change. There is still a lot of research left to do, and is being undertaken by various international organizations.

The Kerguelen Plateau and its islands are a fragile ecosystem. Since it is isolated from human activity, it is also important from the aspect of biodiversity conservation.

References

Barnes, D., Fleming, A., Sands, C., Quartino, M., & Deregibus, D. (2018). Icebergs, sea ice, blue carbon and Antarctic climate feedbacks. Philosophical Transactions Of The Royal Society A: Mathematical, Physical And Engineering Sciences, 376(2122), 20170176. https://doi.org/10.1098/rsta.2017.0176

Bax, N et al. Carbon storage by Kerguelen zoobenthos as a negative feedback on climate change. The Kerguelen Plateau: Marine Ecosystem + Fisheries Proceedings of the Second Symposium. Retrieved 13 June 2022, from http://heardisland.antarctica.gov.au/__data/assets/pdf_file/0019/229141/18-Bax-EA.pdf.

Bressan, D. (2020). Kerguelen Plateau Is Earth’s Longest Continuously Erupting Supervolcano. Forbes. Retrieved 13 June 2022, from https://www.forbes.com/sites/davidbressan/2020/11/06/kerguelen-plateau-is-earths-longest-continuously-erupting-supervolcano/?sh=118a0ba032c8.

Coffin, M. (1994). Large Igneous Provinces. Retrieved 13 June 2022, from https://www.ldeo.columbia.edu/~polsen/nbcp/lipmc.html.

Dell, J. (2019). Australia’s only active volcanoes and a very expensive fish: the secrets of the Kerguelen Plateau. The Conversation. Retrieved 13 June 2022, from https://theconversation.com/australias-only-active-volcanoes-and-a-very-expensive-fish-the-secrets-of-the-kerguelen-plateau-123351.

The End of Fish?

They are one of the original species that inhabited the earth. They are the main source of protein for 3 billion people. They affect the livelihoods for 600 million people. They play an important role in nutrient cycles that sustain aquatic ecosystems. They are an obstacle against climate change by partaking in carbon sequestration. They are essential contributor to life on Earth. They are on the path to extinction.

Plastic: Nylon fishing nets are an efficient and predominant tool of the trade but also account for roughly 10 percent of the plastic debris. Every year 500,00 to 1,000,000 tons of plastic from fishing gear are discarded into oceans. They harm the underwater ecology in a variety of ways the two most notorious being: the degradation of microplastics and the entanglement of wildlife. The microplastic formation can arise either through discarded fishing gear or simply through prolonged and repetitive use of the gear. The entablement of wildlife happens simply by carelessly or purposefully discarding nets, lines, or ropes into the sea, and the sheer amount discarded causes harm through strangulation, cutting into flesh and muscles severing arteries, and trapping animals underwater that need to surface for air, to a wide variety of marine life ranging from fish to whales.

Overfishing: Catching fish provide a rich source of protein and economic opportunities to a large portion of the human population, so isn’t inherently bad as long as enough time and numbers are present to allow for the species to replenish, this is where the problem of overfishing comes from. Through the advancement in fishing technologies, increasing demand, and illegal fishing, fish and other forms of edible marine life are being caught at an alarming rate. How does this affect the ocean? By significantly affecting the population of one species it creates a domino effect that alters the existence of other species in that food web along with an increase in the growth of algae and a decline in the health of coral, thereby damaging the ocean’s biodiversity for a prolonged period.

Along with the countless targeted fish, other unwanted species and sometimes endangered ones can be thrown back into their habitat unharmed but are at times discarded dead due to a lack of concern on the fishermen’s part, resulting in unneeded causalities along with ones that are overfished. How does this affect people? The fishing industry worldwide currently offers jobs for around 60 million people and supplies the demand for close to 3 billion people. When the species of fish disappear so do the jobs they offer, this is significantly detrimental to developing coastal communities, who do far less damage to marine life than their commercial counterparts due to their small scale, but the overexploitation by the latter will render the former obsolete and will, in turn, affect the protein intake from fish in these communities.

Climate change is another by-product brought about by overfishing that has a circular effect on the fishing industry. Climate change brings about sudden rises in temperatures and acidification of the ocean’s water leading to the degradation of marine habitats and loss of species and in turn overfishing leading to less fish which leads to less carbon sequestration.

Damaging fishing methods: While with regulations, methods such as purse seine, trawling, gillnet, longlines, etc., that are generally associated with overfishing can be eco-friendly, there are some methods practiced that no matter what regulations are made will lead to irreversible damage. Blast fishing, dynamite, or homemade bombs are used to indiscriminately kill a large number of fish and bring about the destruction of the physical environment notably coral reefs. Bottom trawling involves towing a net at the very bottom of the ocean to capture bottom-dwelling fish such as shrimp, cod, squid, and rockfish, as this process is carried out damage is inflicted on the seabed communities. Cyanide fishing is a method used to catch live fish for aquariums, a sodium cyanide mixture is sprayed onto the fish habitat to stum them, there are two adverse effects from this method, one being what the previous two methods lead to which the damage of the targeted fish’s habitat, the other being the mortality rate of the fish within 48hrs of capture is 75 % so in other to compensate this loss is an extra amount of fish are targeted.

According to an article published in 2006 and by the recent Seaspiracy documentary, the oceans are predicated to be empty of fish by 2048, although this date has been disputed by various experts, the underlying concern it carries is still relevant and steps need to be taken to counter the above mentioned sources and various others in order to alleviate us from the possible future.

Sustainability of Seafood

Seafood is a common source of protein and ensures food security in many coastal regions across the world. The seafood industry also has economic importance- serving consumers and exporting delicacies and popular varieties of fish, crab, shellfish, etc. However, overfishing and certain aquaculture practices have raised environmental concerns.

Is seafood sustainable?  Does the seafood industry cause environmental problems? And is seafood better than other types of meat? These are some questions that will be answered subsequently.

Aquaculture is the process of cultivating aquatic life for our consumption. This happens in natural marine habitats or in controlled environments that replicate marine habitats. There are many stages in aquaculture. The first stage is the hatchery (collecting eggs, breeding of fish). The fish are then transferred to the farm where they are grown to their full size. Then they are harvested, processed, packaged and transported to stores and markets (Global Seafood Alliance, 2019).

Environmental impacts of aquaculture

Certain species like salmon consume wild fish as their food. So, it takes more than one kilogram of wild fish to produce one kilogram of salmon (Greenberg, 2014). This leads to overfishing to meet the dietary needs of the species being cultivated.

Aquaculture also generates waste through fecal matter and unused feed. The waste is nitrogen-rich and causes oxygen depletion if they are discarded in marine environments. This would choke aquatic organisms in the ocean. The use of pesticides and antibiotics in aquaculture produces chemical waste that pollutes ocean water.

Shrimp farming mostly occurs in tropical and subtropical ponds, within mangrove forests. When pollutants accumulate in shrimp farming ponds, the ponds are abandoned and cultivation is continued in a new pond. This results in the destruction of mangroves, which also host other species of fish and offer coastal protection against cyclones. Therefore, organic aquaculture has started gaining importance, to protect mangroves and sustain people’s livelihood (Greenberg, 2014).

The fishing industry also removes reproductively mature fish from their natural environment, which leads to population decline of fish. Overfishing can slow down the growth of fish population and disrupt the marine food chain. It threatens the livelihood of small fishermen who depend on the daily catch for food and income (Pariona, 2017).

Harmful fishing techniques

These are two ecologically damaging fishing techniques, that are now being banned by many countries due to the problems they cause.

  1. Bottom trawling – Fishermen drag a net along the seabed. This disturbs the sediments that had settled at the bottom. The sediments are carried to other parts of the ocean by the currents.  Accumulation of sediment creates murky water, which blocks the sunlight from reaching underwater plants, creating oxygen-deficient regions. Pollutants that had settled at the seabed are stirred up and enter the food chain, poisoning marine life.
  2. Blast fishing – Explosives are used to kill large numbers of fish at once. This destroys coral reefs and causes oceanic noise pollution (Greenberg, 2014).

Waste generated by aquaculture

Fodder waste and chemical pollutants not only pollute the local ocean water, but can be transported throughout the ocean, affecting different levels of the food chain. It could affect the growth of plankton, and subsequently reduce biodiversity.

Aquaculture waste, once treated, has many uses and economic potential. Fodder waste can be converted to biogas or as fertilizers for soil.

Chitin, obtained from the exoskeleton of crustaceans (crabs, lobsters, shrimp), is used as an additive in fish food. Chitin also has other applications in the medical field.

The process of obtaining chitin also recovers carotenoids. Shrimp waste has economic potential due to the presence of carotenoids. Carotenoids are responsible for the color in shrimp and shellfish. Once extracted and processed, they are used in the food industry and the cosmetic industry.

Compounds like enzymes and proteins could be used in the pharmaceutical industry, and the methods to extract these from seafood waste are being researched (Arvanitoyannis & Kassaveti, 2008).

Seafood production and climate change

The rising temperature of ocean waters due to global warming has reduced fish productivity and changed the distribution of fish population. This hurts seafood production, especially in the tropical countries who are most dependent on seafood for food and money.

Warmer water increases the risk of algal blooms, which will hamper aquaculture. Aquaculture farms will shift their location depending on the condition of the water and marine productivity (Palardy, 2022).

Yet, seafood has the potential to become one of the most sustainable ways of achieving food security for the future.

Seafood can be sustainable

Currently, the seafood industry is criticized for causing overfishing, water pollution and marine degradation. In spite of these environmental impacts, it has the potential to become sustainable if managed efficiently, with proper waste recycling and treatment, and policy measures to ban hazardous fishing methods and overfishing.

Seafood has higher protein retention compared to other types of meat like pork, chicken and beef. Aquaculture is more resource efficient; it has lower greenhouse gas emissions, water demand and land requirement than land-based meat production (Greenberg, 2014).

Some varieties of seafood have lower environmental impact than other varieties. For example, farmed shellfish, mollusks, sardines, mackerel and herring have low environmental impact compared to catfish aquaculture and shrimp. This is because more energy is used for water circulation in the latter.

Mollusk aquaculture (oysters, mussels, scallops) has a positive impact on marine environment because mollusks absorb excess nutrients from water, that would otherwise harm the ecosystem. Capture fisheries do not use fertilizers and thus generate less pollution compared to intensive fish farming (Ma, 2018).

Therefore, consumers also play an important role in the sustainability of seafood by choosing species that have low environmental impact for cultivation and sourcing their seafood from fisheries that follow sustainable practices.

References

Arvanitoyannis, I., & Kassaveti, A. (2008). Fish industry waste: treatments, environmental impacts, current and potential uses. International Journal Of Food Science &Amp; Technology43(4), 726-745. https://doi.org/10.1111/j.1365-2621.2006.01513.x

Greenberg, P. (2014). Environmental Problems of Aquaculture. Earth Journalism Network. Retrieved 17 June 2022, from https://earthjournalism.net/resources/environmental-problems-of-aquaculture.

Ma, M. (2018). Choice matters: The environmental costs of producing meat, seafood. UW News. Retrieved 17 June 2022, from https://www.washington.edu/news/2018/06/11/choice-matters-the-environmental-costs-of-producing-meat-seafood/.

Palardy, J. (2022). Seafood Production Suffers Under Climate Change, but Sustainable Reforms Can Help Maintain Harvests. Pew. Retrieved 17 June 2022, from https://www.pewtrusts.org/en/research-and-analysis/articles/2022/05/11/seafood-production-suffers-under-climate-change-but-sustainable-reforms-can-help-maintain-harvests.

Pariona, A. (2017). What Is The Environmental Impact Of The Fishing Industry?. WorldAtlas. Retrieved 17 June 2022, from https://www.worldatlas.com/articles/what-is-the-environmental-impact-of-the-fishing-industry.html.

What is Aquaculture, and Why Do We Need It?. Global Seafood Alliance. (2019). Retrieved 17 June 2022, from https://www.globalseafood.org/blog/what-is-aquaculture-why-do-we-need-it/.

Deep Sea Pollution?

When we think of pollution in the seas, what generally comes to mind are oils spills, great pacific garbage patch, wildlife entanglement, and microplastic, a commonality between all these is the easy exposure due to proximity to the surface because of this less is known of the majority of pollutants affecting the oceans, are in the deep seas.

In the scope of plastic waste, over 99 percent of it is present on the ocean’s floors or midway at around 180 meters to 460 meters below sea level as opposed to the surface, to make this comparison more visceral, consider the notorious imagery of “the great pacific garbage patch” which amounts to merely a 0.29 % of the total plastic waste present in the seas due to some of the research on the distribution of plastic content in the oceans it is reasonable to assume there are four times as much present in the depths below the garbage patch. It has even been found in some of the deepest most remote parts of the Mariana trench.

Concerns arise even further when we apply this phenomenon to the other form of plastic formed due to overtime degradation of its debris, microplastics. Microplastics are known for contaminating entire ocean food chains and scientists have discovered that large quantities are carried by bottom currents to concentrated spots to form microplastic hotspots, one example is located in the Tyrrhenian Sea. These same currents are also responsible for transporting nutrients and oxygenated water, implying that the microplastic hotspots form in the same regions as significant ecosystems filled with marine life. 

Another notable scope of pollution that affects the deep sea comes in the form of chemical waste most significantly as pesticides, toxic metals, and pharmaceuticals, which come to about 100 million tons currently present, out of these the most alarming toxins identified by researchers were persistent organic pollutants, PCBs and PBDEs, both of which have been slowly phased out from widespread usage but as the category “persistent organic pollutants” suggests they stuck around in the environment to this day. Their effect can be illustrated through research conducted in the aforementioned marina trench. They are capable of traveling great distances indicative of their presence in such a remote area like the Marina trench, and they don’t dissolve well in water and favor sticking to the surface of materials such as we mentioned before deep-sea plastics. Creatures attracted by the colorful allure consume them, where the “persistent organic pollutants” remain building up in their fat tissue. Upon death, their bodies sink to the ocean floor to be consumed by deep-sea crustaceans, thus incorporated into the food web.  

Interceptor technology for rivers prevents plastic discarded in them to reach the ocean, creating an artificial coastline to remove the garbage, and several other measures undertaken to clean up the oceans are encouraging examples indicating a brighter future for the oceans, but the lack of initiatives towards the deep sea is equally as concerning.

The Beautiful Coral Reefs

Corals belong to the phylum Cnidaria, a group that include gelatinous stinging marine invertebrates like jellyfish and sea anemones.

Coral reefs are composed of the skeletons of marine invertebrates called corals and the each tiny individual coral is polyp. The coral species build reefs by extracting calcium carbonate from seawater to create a hard, durable exoskeleton that protects their soft, sac-like bodies. These are called hard corals. Other species of corals that are not involved in reef building are known as soft corals such as sea fans and sea whips.

Coral polyps live on the calcium carbonate exoskeletons of their ancestors, adding their own exoskeleton to the existing coral structure. As the centuries pass, the coral reef gradually grows, one tiny exoskeleton at a time, until they become massive features of the marine environment. Coral have an array of shapes and colors, from round, brain like to tall with intricate and vibrant colors.

Corals of different shapes, size and colors

Corals are found all over the world’s oceans, from the Alaska to Caribbean sea. However, the biggest coral reefs are found in the clear, shallow waters of the tropics and subtropics. The largest coral reef system is the Great Barrier Reef in Australia which is more than 2,400 kilometers in size.

Corals feed by one of two ways.

Most corals depend on zooxanthellae, a photosynthetic algae which lives inside the coral polyp’s body where they produce food – carbohydrates to corals and for themselves. The coral reefs inturn provides a protected environment and the components to the algae. The corals and the algae share a symbiotic relationship wher both the organisms are benefited by each other.

In addition, zooxanthellae also provide the corals with their lively colors as most coral polyps are colorless without zooxanthellae.

However, some species of corals, mostly the deep corals in the lower, colder zones of the ocean directly catch small marine life, like fish and plankton, by using the stinging tentacles on the outer edges of their bodies.

About the reproduction of the coral species, they reproduce both sexually and asexually. Asexual reproduction happens through budding when new clonal polyps bud off from the parent polyp and grow and form their own colonies. Sexual reproduction occurs during a mass coral spawning. Coral spawning is an annual event when the corals release both eggs and sperms to fertilize. Later, the fertilized eggs develop into coral larvae, which grow further and form their own colonies or reef.

Coral spawning at Great Barrier Reef

Coral reefs are divided into four categories and they are:

  • Fringing reefs – grow near the coastlines around islands. They are most commonly found in the Phillipines, Thailand, Timor-Leste, off the western coast of Australia. Ningaloo reef is the largest fringing reef along the western coast of Australia. In India, the fringing reefs are found in the Gulf of Mannar and Palk Bay.
  • Barrier reefs – similar to fringing reefs, formed when fringing reefs combine with each other and border the coast. They are separated from shores by deeper and wider lagoons.

Example: Great Barrier reef, off the northeastern coast of Australia in the Pacific Ocean.

In India, Barrier reefs can be found in Andaman and Nicobar Islands.

  • Patch reefs – small, isolated reef growing from the bottom of the continental shelf. Patch reefs are present in Ratnagiri, Malvan and Kerala coasts of India.
  • Atoll – is a ring shaped coral reef island in the middle of oceans. Kiribati atoll in the west-central Pacific Ocean is the world’s largest atoll.

The union territory of India, Lakshadweep is also an archipelago consisting of 12 atolls.

Coral reefs are mostly found in warm, clear, shallow water with plenty of sunlight to nurture the algae that the coral rely on for food. Coral reefs covering less than 1 percent of the ocean floor are the most productive and diverse ecosystems on the earth. Hence are called “rainforests of the sea”. Coral reefs are critical marine habitat as they provide home and nursing to around 25 percent of marine life including 4,000 species of fish.

Importance of Coral reefs

  • Coral reefs benefit around 1 billion people with an estimated $30 billion annually in direct economic benefit to people worldwide from the various ecosystem services it  provide including food, coastal protection, and income from tourism and fisheries.
  • They act as wave barriers protecting the coast from erosion and the costal communities of adverse climate events.
  • Attracts millions of tourists every year, adding to the country GDP.  

Threats to coral reefs

Increasing temperatures of the world’s oceans due to global warming is causing coral reefs to expel zooxanthellae. Post which the coral reefs loses their color and are deprived of food eventually leading to their death. Coral reefs losing their color is termed as Coral Bleaching which is an increasing cause of concern.

Also, ocean absorbs immense amounts of carbon dioxide released into the atmosphere through fossil fuel burning which is causing high acidification of the ocean which in turn is inhibiting coral’s ability to produce calcium carbonate exoskeletons, the shelter base of corals.

Agricultural pesticides, chemical fertilizers, sewage discharge, oil, gasoline and sediment from eroded landscapes is polluting the ocean waters, making it difficult for coral to thrive and therefore damages the complex relationships that exist among the marine life and corals.

Unsustainable fishing practices such as cyanide fishing, blast fishing  with explosives and fishing using trawlers is destroying a thousand-year-old complex coral reef system.

The destruction of coral reef around the world, can lead to the extinction of thousands of species of marine life and make coastline communities and infrastructure susceptible to havoc causing storms and cyclones. Some islands and low-lying countries would vanish under the water due to it. Also damaging the economy of various coastal countries.

Healthy corals are the foundation of the Ocean’s food chain contributing immensely to our economy. It has geographical, economical and cultural importance.

Healthy corals lead to healthy oceans, and healthy oceans are vital to all life on Earth. Hence, protecting coral reefs is of utmost importance.

References:

https://www.noaa.gov/education/resource-collections/marine-life/coral-reef-ecosystems#:~:text=Coral%20reefs%20protect%20coastlines%20from,food%2C%20income%2C%20and%20protection.

https://www.epa.gov/coral-reefs/threats-coral-reefshttps://www.unep.org/explore-topics/oceans-seas/what-we-do/protecting-coral-reefs

Oil-Eating Bacteria: A Solution to Clean our Water Bodies

Oil spills can destroy the biodiversity of a region and can have an indelible negative impact on the environment. Since the 1970s the average number of oil spills recorded at 20 spills per year has significantly reduced in the recent past. In the decade from 2010 to 2019, the average spill recorded in a year was 1.8 (Sönnichsen, 2022). But the problem of clearing the oil from these spills regardless of the extent of damage is an arduous task. One of the solutions by way of scientific research is the discovery of oil-eating bacteria. Ever since its discovery, several initiatives have been taken to use it as a tool to clean water bodies polluted with oil-based substances like petrol and diesel.

Historical significance

Oil-eating bacteria belong to several families including Marinobacter, Oceanospiralles, Pseudomonas, and Alkanivorax, that can consume compounds of petroleum (Thrift-Viveros, 2015). There are close to 7 species of bacteria that can eat petroleum-based products as part of their diet.

The Pseudomonas bacteria were genetically engineered by Prof. Anand Mohan Chakravarthy in 1971 which received tremendous attention worldwide owing to the number of oil spills that were prevalent during the period. In the mid-1990s, other bacteria like Alcanivorax and Marinobacter were isolated.

These oil-eating bacteria have a large potential to tackle oil spills across the world since oil has almost become a part and parcel of the economic functions of a society. Even if there comes a time in the future of electric vehicles and less fossil fuel-dependent energy resources, some sections of the societal functions will be dependent on oil which would need to be transported. This would further also leave room for oil leaks to occur by external forces beyond the control of human actions for which these oil-eating bacteria will come to the rescue.

How does the bacteria’s diet work?

Oil-eating bacteria are present as communities across several regions including the Persian Gulf and Arctic conditions of Alaska. Such bacteria have the capacity to degrade hydrocarbons from where they derive their ability to eat oil (Verran, 2020). These bacteria are adapted to the climatic conditions of that region and the more adapted they are to the natural environment, the better their capacity to eat oil quickly. In addition to the climate, the amount of oxygen and nutrients in the water, temperature of the water, the surface area of the oil, and the type of oil impact the oil-eating capacity of the bacteria. For insurance, some bacteria may be in a position to consume oil more quickly from water during the summers as compared to winters and they can eat light petroleum products like gasoline and diesel better as compared to heavy petroleum products like crude oil and fuel. 

Indian context

India is not new to oil spills and has been a victim of several such spills even in the recent past. The most recent of the incidents is the Ennore oil spill in 2017 along the coast of Chennai wherein 60 tonnes of oil (Ennore Oil Spill: What Happened? 2017). The impact was felt across several ports. Dead turtles washed up on the shore as a result of the leak. Though efforts were taken to clear the same, oil-eating bacteria could have definitely enhanced the clean-up process. The argument that efforts should be taken to prevent them is necessary, but that does not solve the oil leaks that have already occurred. It is for this reason that we need oil-eating bacteria.

References

Ennore oil spill: What happened? (2017, November 9). The Hindu. Retrieved May 20, 2022, from https://www.thehindu.com/news/cities/chennai/ennore-oil-spill-what-is-happening/article20044550.ece

Sönnichsen, N. (2022, February 9). Global average oil spills per decade 2021. Statista. Retrieved May 20, 2022, from https://www.statista.com/statistics/671539/average-number-of-oil-spills-per-decade/

Thrift-Viveros, D. (2015, June 5). Who Thinks Crude Oil Is Delicious? These Ocean Microbes Do. NOAA’s Office of Response and Restoration. Retrieved May 20, 2022, from https://response.restoration.noaa.gov/about/media/who-thinks-crude-oil-delicious-these-ocean-microbes-do.html

Verran, J. (2020, February 25). Can oil-eating bacteria clean up our seas? Microbiology Society. Retrieved May 20, 2022, from https://microbiologysociety.org/news/society-news/can-oil-eating-bacteria-clean-up-our-seas.html

Slippery sailors of the sea: India’s Sea snakes

In Indian mythology, Vishnu, the Lord of preservation, is said to have been supported by a giant sea snake called Shesha that rests on the cosmic ocean upon which the entire world is balanced. Snake Vasuki was wielded as a rope to churn milk from the ocean. Our myths, legends and stories have always integrated sea snakes and serpents into their storylines. Whether these stories have portrayed them as holy, higher entities or as ruthless monsters, they have familiarized the idea of sea snakes in us since our childhood. Out of the 3000 species of sea snakes found across the globe, India is endemic to 26 species according to a report catalogued by Chennai’s National Centre for Sustainable Coastal Management (NCSM).

Herpetologist Nirmal Kulkarni says that all snakes can swim. “In fact, all snakes are good swimmers and have to drink water in order to survive. Water snakes are a common grouping of snakes that are found in the vicinity of water bodies.” But land snakes and sea snakes are distinctly different from each other in their physiology, adaptations and behaviour. Sea snakes, which are largely venomous creatures that fall in the Elapidae or cobra family, have a flatter body than land snakes and own rudder-shaped tails that facilitate them in sifting through their marine ecosystem. Eyes and nostrils are situated at the top of their heads for most sea snakes. As air-breathing creatures, these features aid them in breathing with only the tip of their head peeking above the surface of the water. Although some of these slithering monsters could grow as long as 2.7 metres, most adults attain a length of 1–1.5 metres during their lifetime.

Sea snakes are categorized into two basic kinds. True sea snakes, which are labelled under the genus Hydrophis, are the ones that live their whole life exclusively in the sea. The other variety called sea kraits is segregated into the genus Laticauda and consists of snakes that favour plodding in estuaries, mangrove swamps, coral reefs and mud flats rather than in the nearby water body itself. 52 of the total sea snake species are identified as true sea snakes.

Sea snakes are predominantly found in the tropical and sub-tropical coastal regions of the Indian and Pacific oceans. The hook-nosed sea snake (Hydrophis schistosa) is the most prevalently found species in India. They are distributed across a range of deep and shallow waters. Also known as Beaked sea snakes, these are lethally venomous creatures who rely on their toxins to catch their prey instantaneously in the aquatic ecosystem. They possess a beak-like or hook-like rostral scale that protrudes above their mouth. They are usually known to prefer sea catfishes, eel-tailed catfishes and pufferfishes. Annulated sea snake (H. cyanocinctus), which has unique triangular stripes over a cream coloured body, and the many-toothed Malacca sea snake (H. caerulescens) are two other types in the Hydrophis genus or true sea snakes that are native to India.

The Rainbow Water Snakes (Enhydris enhydris) are largely freshwater snakes that pervade settings like marshlands, ponds, rice paddies etc. Two long, pale stripes run down the length of its body and intersect on the crown.

In the other category of Sea Kraits in the Laticuda genus, India is home to Banded Sea Krait (Laticauda colubrina) and Blue Lipped Sea Krait (Laticuda laticaudata). The Banded Sea Krait also referred to as yellow lipped sea krait, are nocturnal species that contain alternating markings of black with blue, white or grey rings. They also have a prominent yellow snout, thus the name Yellow lipped sea krait. These snakes crawl up into limestone caves and rock crevices to lay their eggs. The Blue Lipped Sea Krait or Blue-ringed sea krait is the reptile replica of the blue-black version of “Is the dress blue-and-black or gold-and-white?” It is found in abundance on the coasts of the Bay of Bengal.

Some other sea snakes that traverse the oceans of the Indian Ocean are Annandale’s Sea Snake (Kolpophis annadalia) and Shaw’s Sea Snake (Lapemis curtus). From Genus Rhabdops, species like Rhabdops olivaceus and the Rhabdops aquaticus populate the streams of West Bengal.

However, the continuity of these sea snakes is threatened by climate change, excessive fishing and increased human intervention. Sea snakes are found as bycatch in fishing nets and are often killed or left to die by the fishermen. Although these snakes are protected under schedule IV of the Indian Wildlife (Protection) Act, 1972, they are of no economic value to the fishermen, and that lands as a huge disadvantage to the sea snake population. A significant incident of Mass bycatch would be the one in Goa where 81 hook-nosed sea snakes were found dead over an expanse of beach shore as small as 30 meters. Tragically, the same woe repeated itself only a couple days ago with 69 dead hook-nosed sea snakes. We could prevent such incidents by directing more incentives to sea snake monitoring and research, more funds into constructing safer fishing gear etc.

References

  1. Distribution of Sea Snakes in the Indian Coastal Waters by P. Kannan and M. Rajagopalan
  2. Sea snakes – britannica.com
  3. ecologyasia.com
  4. Threatened and undocumented sea snakes of India – Mongabay news