The world underwater is one that is mysterious, intriguing and full of surprises. It is an ecosystem that is so unique and diverse with a life of its own. From bacteria to protozoans to crustaceans to fishes to some of the largest animals found on planet Earth, the marine biodiversity is ever evolving and increasingly diverse.
Marine biodiversity is an aggregation of highly inter-connected ecosystem components or features, encompassing all levels of biological organization from genes, species, populations to ecosystems, with the diversity of each level having structural and functional attributes. It encompasses all plant and animal species and their relationship with the physical environment that they inhabit. Why is marine biodiversity important?
What is so special about marine biodiversity?
The oceans and seas are one of the biggest storehouses of biodiversity. It comprises 90% of the habitable area on the planet and is home to approximately 250,000 species with several undiscovered ones. The waters and the organisms in it are vital to the health of the planet. Genetically and ecologically diverse oceans have been linked to maintenance of natural balance. They supply half of the oxygen we breathe and are responsible for the absorption of one quarter of the carbon dioxide that is released through anthropogenic activities. A crucial component of marine ecosystems that sometimes is forgotten are coral reefs.
Coral reefs are at a high risk of extinction. They are extremely fragile and are more susceptible to adverse effects of climate change and other threats. They make for one of the most productive habitats in marine ecosystems.
What role does marine biodiversity play for humans?
Humans are both directly and indirectly dependent on the oceans for their livelihoods. Marine ecosystems are a source of income to a large proportion of the population along the coastlines. They help with tourism and recreation. They also provide other services like protecting coastal areas from erosion and prevention or curbing of natural disasters like floods, tsunamis and drought through organisms like the mangrove species. 38% of the world’s population lives within 100kms of coasts all around the world. Mangroves support large economies, as well as wildlife. This allows for sustainable economic development, labour for all, sustainable livelihoods and the cultivation of healthy relationship between man and nature.
The ecological and economic services provided by marine biodiversity are numerous but like every other component of nature, the organisms and the marine environment are under several threats at present. These threats have been on the rise with increased exploitation of resources and failure of policies to sustain diversity in different ecosystems. Some of the major threats to marine biodiversity include climate change, habitat destruction, over exploitation of marine resources, pollution and introduction of alien species.
Climate change
Marine ecosystems are very fragile. They respond very quickly to even slight fluctuations in their physical environment, but at the same time adapt to these conditions at the same rate. Global warming causes the temperature of water in oceans, seas and estuaries to rise. This rise in temperature can be detrimental if the trend is an upward one. The rise in temperature can be caused by direct sources or indirect sources. Direct sources include industries that expel warm or hot water after utilisation of the naturally occurring water in coastal power plants. The higher temperature of water makes it absorb oxygen inefficiently.
At the same time, the atmospheric carbon dioxide levels are increasing as humans continue to burn fossil fuels. This increase in temperature can affect the reproduction of certain organisms. For example, Loggerhead turtles in Florida have been giving birth to 90% females owing to high temperature. If the temperature goes up by even one degree, there will be no more male offspring. Coral reefs have an optimum temperature requirement of 23-29℃. Increasing temperature can lead to coral polyps releasing zooxanthellae that can result in bleaching.
Habitat Destruction
Both natural and man-made events have caused habitat destruction in several marine ecosystems. Natural events like typhoons, cyclones and tsunamis can temporarily disrupt the life cycle of several organisms but anthropogenic causes are more prominent and damaging. Wetlands and rivers are dredged to accommodate industries and create land for agriculture. Countries depend on shipping for exports and imports. Shipping can adversely affect the biodiversity. Oil spills can completely destroy the viability and productivity of oceans and seas. The productivity of these ecosystems is dependent on the diversity of organisms present. When habitats are destroyed, species’ numbers go down drastically, resulting in associated damages like simultaneous extinction of plant and animal species.
Over exploitation
Overfishing (Image source: Wikipedia)
Coastal communities are dependent on marine resources for their livelihoods. In their race to survive, more often than not, these marine resources are overexploited. A predominant threat includes overfishing. Fishing is not inherently bad for the oceans, but when it crosses a limit, it can result in irreversible damage. The number of overfished stocks has tripled in the last 50 years. Today one-third of the world’s fisheries have been pushed beyond their biological limits. As is, overfishing results in considerable reduction in species numbers but by catches also contribute to marine wildlife decline. Illegal fishing also accounts for some of the worst ocean impacts.
Pollution
Industrial effluents that are untreated damage several plant and animal species. These effluents contain harmful chemicals that alter the pH, temperature and elemental composition of the water and disrupts the natural equilibrium. Unfortunately, sewage also find its way to seas and oceans in specific dumping spots. Presence of nutrients in the water can result in eutrophication. In some cases, algae can overgrow the coral reefs, using up all the nutrients present in its habitat.
Oil spilling from tankers disasters, ballast water and bilge washings are very harmful to animals. They can drown birds feeding on fishes and can even cause hypothermia. Hypothermia is experienced by organisms in an oil spill, when the oil creates a sticky layer called mousse on their surface making respiration and insulation difficult.
Alien species
Introduction of alien species is considered another one of the greatest threats to marine biodiversity. Invasive species can dramatically alter the productivity of the ecosystem and can cause rapid extinction of fishes and other animals and plants. For example, the arrival of an invasive jelly fish like organism, Mnemiopsis leidyi in the Black Sea led to the collapse of commercial fisheries in the region. Killer algae, Caulerpa taxifolia, escaped aquariums and used up all nutrients in the Mediterranean. Alien species have also destroyed much terrestrial wildlife.
The threats to marine biodiversity are very real, but all is not lost. There are things we can do to protect our seas and oceans and its biodiversity. As consumers, checking the source of your fish can be helpful in realising the nature of industry. Purchasing sustainably caught fishes helps protect these species. Waste disposal is another crucial component. Making sure everything that exits our houses are properly segregated and being conscious of the manner in which we dispose waste at tourism spots is also important. Being mindful of your carbon footprint, using lesser plastics, supporting organisations working to protect the oceans taking care of our beaches are some of the ways you can contribute to restore oceans.
Help us Help Them
Help us Help Them! Think Wildlife Foundation is a non profit organization with various conservation initiatives. Our most prominent campaign is our Caring for Pari intiative. Pari is a rehabilitated elephant at the Wildlife SoS Hospital. 25% of the profits from our store are donated to the elephant hospital for Pari. Other than buying our wonderful merchandise, you could donate directly to our Caring For Pari fundraiser.
Written by: Manasa Ramesh