The biggest threat for oceans would probably be oil spills. Every year oil spills pollute a large oceanic space shattering the lives of aquatic animals and even of some birds which depend on these ocean species. Oil spills form a layer on water due to their lesser density. Surface dwelling fishes get stuck in these spills, even if they manage to free themselves the oil rubbed on their body makes it hard for them to swim around and at times blocks their gills. Birds which depend on fish from the ocean also get stuck in these spills. Oily feathers make it impossible for them to fly any further. Another ill-effect caused by ships is the unrestrained amount of noise pollution they cause. The main reasons for this being a major issue is that noise travels much faster and with higher intensity in water and aquatic animals are more extremely sensitive to sound. This affects marine species extensively resulting in changed diving directions and patterns, navigating to other regions, panic reaction, hemorrhage, and even damage of internal organs.
Another human activity that adversely affects marine life is dredging. This is the process of removing excessive sand or sediments at sea beds near harbors to maintain its depth suitable for all kinds of ships to enter the port without being ceased by ocean floors. The removed sediment is later displaced to some other ocean region. But this kind of activity has a wide range of side-effects. When soil is removed it loosens the ocean floor releasing harmful substances and weakening coral roots. Since soil is scooped up entirely it can destroy many coral beds. Moreover, harmful substances can now easily spread to other parts of the ocean. Species of a particular region would be used to that particular ocean bed, when a different kind of soil is added to that region it affects growth and survival of the indigenous creature. This may pave way to invasive species. The newly added soil profile could be deficit or excessive of vital nutrients. Dredging also increases water turbidity. These effects can happen even when destructive land erosion takes place. But their intensity is particularly higher in the case of dredging and erosion is a natural process which occurs infrequently while dredging is a periodic process carried out regularly.
In addition to this, over fishing and invasive species have had severe effects on ocean population. Fish has been a staple source of food for many people, besides fishing has been an occupation for humans since time immemorial. So, where is the issue? Well human population has soared rocket high leading to drastic fishing, consequently, extinction of numerous aquatic species. The main attribute to extinction is when we fish more than its natural capability to replenish itself i.e., we fish more than they are born. This happens mainly when fishes with long life span are caught. These take longer duration to reproduce and grow thus being small in numbers, when they are over fished it leads to extinction. Commercial whaling is one such destructive habit which has left the whale population endangered. This why commercial whaling is banned in many countries. Invasive species may not only be plants but many aquatic animals also move to new sea floors as their earlier habitat might be disrupted. This process has been extensive in recent years due to increased human activities which are predominantly destructive.
Deep sea trawling or bottom trawling is the worst known method of fishing which is even banned in several countries. This practice uses a huge net tied to the fishing boat and scoops fishes right from the bottom of the sea floor. This practice has surplus amounts of tragic consequences than it does any good. Bottom trawling definitely leads to over fishing, since, the required fish is not selectively caught the amount of “unwanted” dead fish thrown back into the sea is huge. This leads to more fish wasted than fished. Bottom trawling also affects essential corals and important species which may not be useful for fishermen but are essential for the ocean ecosystem. This practice also makes the water turbid, disrupts ocean floors and displaces species. This not only affects marine species but also local fishermen, aquatic explorers and tourists. Local fishermen who follow more conventional yet sustainable and fuel efficient fishing methods are likely to catch less unwanted fish. But, over-fishing by bottom trawlers has left them with declined fish in the sea affecting their livelihood. Marine enthusiasts and tourists visit various oceans for underwater photography, deep-sea diving, and various exploration. Unfortunately, destruction of corals and species has led to a downward trend in such activities as well, thus affecting the tourism industry.
To be continued……