22nd May is dedicated to Biological Diversity and is celebrated worldwide as International Biodiversity Day. This year it is themed on ‘MARINE BIODIVERSITY’ and emphasizes the importance of the diverse forms of life in the oceans. ZooLander dedicates his column to marine biodiversity, paying tribute to an important segment of the ecological system.
The ocean is home to the blue whale, the largest animal ever to have lived on earth, and to billions upon billions of the tiniest: there are more microorganisms in the sea, than there are stars in the universe. Oceans cover 71 percent of the surface area of the globe, and constitute over 90 percent of the habitable space on
the planet, making it one of the most important habitats of the world.From sandy shores to the darkest depths of the sea, the ocean and coasts support a rich diversity of life. People have lived near and fished from the ocean for thousands of years and even today, an estimated 41 percent of the world’s population lives within 100 km of the coast, and fisheries provide over 15 percent of the dietary intake of animal protein as per statistics of the Convention of Biological Diversity (CBD) which selected “Marine Life” as the theme for the International Day on Biological Diversity.
How much life in the Ocean..?
From 2000 to 2010, in an unprecedented international collaboration, scientists around the world, set out to try and determine how much life there is in the sea. Dubbed the ‘Census of Marine Life’, the effort involved 2,700 scientists from over 80 nations, who participated in 540 expeditions. They studied surface seawater and probed the deepest, darkest depths of the ocean, sailed tropical seas and explored ice-strewn oceans in the Arctic and Antarctic.
By the time the census ended, it had added 1,200 species to the known roster of life in the sea; scientists are still working their way through another 5,000 specimens to determine whether they are also newly-discovered species. The estimate of the number of known marine species - the species that have been identified and the ones that have been documented but await classification, has increased as a direct result of the census, now making it around 250,000. (This total does not include some microbial life forms such as marine viruses.) In its final report, the census team suggested it could be at least a million. Some think the figure could be twice as high. So these figures alone highlight the importance of marine life which thrives in the oceans.
Marine life are found in the coastal areas, the continental shelf, the open ocean, the deep ocean and can be in some of the different ecosystems within the ocean world itself, making it one ocean, many worlds.
Along the Coast
Coastal areas, often among the most dynamic and productive of environments, are in many ways the definition of living on the edge. Waves crashing against rocky cliffs or rolling onto sandy shores, form estuaries that exhale the last breath of river systems, the frenetic riverine pace yielding to a sprawling mixture of fresh and saltwater.
In the warm estuarine waters of the tropics, hot and humid mangrove forests are a hybrid of terrestrial and marine life: above the water, they host insects, birds, monkeys, alligators and large mammals like deer and even tigers; beneath the water’s surface, fish swim among mangroves thick roots, which are covered with filter feeders like oysters, mussels, and anemones, while the muddy banks are inhabited by amphibians and crabs.
Continental Shelf
The area fringing coastal landmasses is known as the continental shelf; during ice ages, when sea levels were lower, the shelf was the boundary of the continents but now extends offshore underwater by an average of 80 km. Continental shelf waters are relatively shallow, generally between 100 and 200 metres deep; because their shallowness means they are bathed in sunlight in their upper layers and because their relative proximity to shore provides them with ongoing sources of nutrients from land, they are some of the most productive waters in the ocean. Coral reefs, sea grasses and kelp forests are all in continental shelf waters, as are the vast majority of the world’s fisheries.
The Open Ocean
Peering over the sides of a ship steaming over its surface, it might appear that the open ocean is one big, boundary-free expanse of water – its wildlife swimming back and forth, from surface to depths, without constraint. But marine life researchers found that, although many areas of the open ocean may look equal, to marine animals there are clear differences. The researchers found, for example, that white sharks congregate in an area off Hawaii that scientists dubbed the “white shark cafe‚”, and that several species of turtles, seabirds, seals, whales and sharks all congregate at ‘hotspots’ as in the California Current.
The top 100 meters of the ocean is the zone within which most of the life with which we are instantly familiar -- fish, turtles, and marine mammals, as well as the microscopic plant and animal plankton that forms such an important part of the marine food web – exist. Much deeper where sunlight struggles to penetrate, its another story. Six hundred meters deep, sunlight in the ocean is as bright as starlight on the surface; at 693 meters it is approximately ten-billionth its surface brightness; and by 1,000 meters, the sea is completely dark. And yet, even here, there is life.
The Deep
In the absence of sunlight, many deep sea fish create lights of their own, in the form of bioluminescent symbiotic bacteria that dangle as lures or shine a path ahead like headlights. Marine invertebrates burrow through the silt of the seabed itself. Seamounts, underwater mountains that climb 1,000 meters or more from the ocean floor, often have complex surfaces of terraces, pinnacles, ridges, crevices and craters, and their presence diverts and alters the currents that swirl about them; the net effect is to create a variety of living conditions, providing habitat for rich and diverse communities. There are believed to be in excess of 100,000 seamounts of 1,000 meters or higher, although only a fraction have been studied.
Human Impact and Hope
However, although humanity has frequently benefited from the bounty of the ocean and the wildlife it contains, ocean and marine wildlife has not always benefited from the attentions of humanity. Some species are already extinct, due to unregulated human activities; others, notably the great whales, have been hunted to fractions of their original populations. Commercial over exploitation of the world’s fish stocks is so severe that it has been estimated that up to 13 percent of global fisheries have ‘collapsed.’ Between 30 and 35 % of the global extent of critical marine habitats such as seagrasses, mangroves and coral reefs are estimated to have been destroyed. The burning of fossil fuels is causing the ocean to become warmer and more acidic, with consequences we are only beginning to grasp.
But there is hope. Around the world, species and populations are recovering with effort and intervention from communities and governments; large areas are being established as protected areas, and the Convention on Biological Diversity has established a series of specific targets that require stakeholders at all levels to work together to protect the biodiversity that lives in the ocean, for its own sake and for the benefit it brings to people worldwide.
Fish may be one of your favourite food items. But be mindful that they too are marine life and if we allowed the world’s oceans to be polluted and over exploited, marine species, we will not get fish for our consumption. Let’s all be mindful of Marine Biodiversity and commit ourselves to take special heed to protect this precious resource. on this International Biodiversity Day!
Past themes celebrated on International Biodiversity Day
Marine Biodiversity is the theme for this year’s International Day for Biological Diversity (IDB). Designation of IDB 2012 on the theme of marine ecosystems provides parties to the Convention on Biological Diversity (CBD) and everyone interested in marine life, the opportunity to raise awareness of the issue and increase practical action. The themes of the past Biodiversity Days are listed below...
2012 - Marine Biodiversity
2011 - Forest Biodiversity
2010 - Biodiversity, Development and Poverty Alleviation
2009 - Invasive Alien Species
2008 - Biodiversity and Agriculture
2007 - Biodiversity and Climate Change
2006 - Protect Biodiversity in Dry lands
2005 - Biodiversity: Life Insurance for our Changing World
2004 - Biodiversity: Food, Water and Health for All
2003 - Biodiversity and Sustainable Development
2002 - Dedicated to forest biodiversity
Published on LakbimaNews on 20.05.2012
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