Oceans are getting sicker, let's do something quicker.[Part-1]

Updated: Apr 23, 2020

THREATS TO MARINE BIODIVERSITY

PROLOGUE: Understanding marine biodiversity and its threats are very important for a number of reasons. One could argue that marine biodiversity has innate importance, as life has value on its own. Anthropogenic impact on the oceans is already there to a considerable degree, especially in the coastal areas but increasingly in the open ocean as well. Some threats are:

1. Pollution,

2. Habitat Destruction (loss),

3. Introduction of alien species,

4. Overexploitation,

5. Climate change and Declining marine biodiversity worldwide is a major and on going environmental dilemma.

Attention to biodiversity changes in the oceans is limited and these threats are due to development related activities along almost half of the world’s coasts. The impact of unsustainable developmental activity has caused loss of habitat and massive reductions in our aquatic species biodiversity. Pollution affects many marine organisms. Alien species can dramatically change the structure and function of marine ecosystems by changing biodiversity and eliminating vital components of the food chain which are harmful to our native species. Increment in CO2 results in the decrease of pH of the ocean, due to which acidification causes destruction of corals and coral reefs.




 

INTRODUCTION For centuries the ocean was viewed as a boundless reservoir of productivity with unlimited capacity to assimilate wastes. A productive ecosystem is characterized by a high degree of biological diversity. In other words it contains a large assemblage of plant and animal species and each species has a well defined role to play. A high level species diversity in an ecosystem therefore guarantees stability because many species provide numerous pathways for energy of a system to flow. The Marine biodiversity of the ocean makes it one of the greatest resources for the human species. However, like all resources it must be used with caution so as to remain sustainable. Any decrease in marine biodiversity will have the greatest impact on developing countries risking their primary source of protein food. The resources of the sea have been overharvested by humans thereby threatening marine biodiversity.

 

THREATS Human activities are causing species to disappear at an alarming rate. It has been estimated that between 1975 and 2020, species extinction will occur at a rate of 1 to 15 % per decade. Losses of this magnitude impact the entire ecosystem, depriving valuable resources used to provide food, medicines, and industrial materials to human beings .There are some differences regarding the severity of each threat. Overfishing is the greatest threat to marine environments, other threats to aquatic biodiversity include urban development and resourcebased industries, such as mining, dredging that destroy or reduce natural habitats. Air and water pollution, sedimentation, and climate change also pose threats to aquatic biodiversity. Many species of fishes, sea turtle and other marine animals are killed and discarded bycatch. The composition and structure of the fauna, flora and habitats of coastal seas has been changing at an unusual rate in the last few decades, due to changes in the global climate, invasive species and due to increase in human activities. However, humans do impact the oceans already to a considerable degree, especially in the coastal areas but increasingly in the open ocean as well. At present eutrophication is a primarily a problem of coastal water, particularly in shallow, particularly in enclosed area.



 

INTRODUCTION OF ALIEN SPECIES The introduction of harmful aquatic organisms to new marine environments is believed to be one of the four greatest threats to the world’s oceans. An alien species is one that has been intentionally or accidentally transported and released into an environment outside of its historic geographical range. Such species are described as ‘invasive’ if they are ecologically and/or economically harmful. Invasive species can dramatically change the structure and function of marine ecosystems by changing biodiversity and eliminating vital components of the food chain.


Discharging of Ballast water



These species are harmful to native biodiversity in a number of ways, for example, as competitors, predators, parasites, or by spreading disease. Ships use water as ballast to adjust their position in the water to improve their maneuverability and stability. Mariners typically pump water into ballast tanks at one port and discharge it when taking on cargo at another port. Mariners have unintentionally transplanted locally native marine species to new areas with the ballast water. The arrival of an invasive jellyfishlike organism, Mnemiopsis leidyi, led to a major ecological “regime change” in the Black Sea, which contributed to the collapse of commercial fisheries in the region. Many other species have been introduced as planktonic larvae in ballast water. There are many alien species:

Many seaweeds like

Red alga (Kappaphycus striatum), Zebra mussel (Dreisssena polymorpha),

Lion fish (Aquarium fish),

Caulerpa taxifolia.



Lion fish (Aquarium fish)