How the Future of Underwater Life Relies on the Extent of Climate Change

by Alice Collins

(image: A Shuau)

The whole world is affected by climate change, and as a result delicate ecosystems are becoming particularly at risk. In marine biomes where everything from the temperature of the water, to the concentrations of dissolved substances is vitally important, the changes and impacts climate change brings with it can be monumental.

Most scientists believe that climate change will bring on a whole new era of unpredictable weather due to the rising global temperatures on earth. This unfortunately will lead to the destruction of many marine habitats. Some examples of extreme weather that the earth will face are tropical storms and heavier rainfall. These both occur as a result of increasing global temperatures which cause vaster amounts of water to evaporate into the atmosphere. Both of these can cause much destruction to many marine habitats, particularly coral reefs because they can physically damage these habitats due to the huge forces and swells created in the sea. Extreme weather also increases rates of erosion in coastal areas, so this can damage and destroy many bird habitats which often include nests which can lead to reductions in bird populations because less and less birds can successfully raise their young if they do not have a safe place to feed them and shelter them. For example the UK’s kittiwake population has declined by approximately 60% since 1986 as a result of poor breeding success and low adult survival rates.

Climate change also can cause coral to bleach. A change/increase in water temperature can cause coral to drive out algae. If the temperature remains high for too long the coral will not let the algae back and the coral will die. The microscopic algae is called ‘zooxanthellae’ and it lives within the coral in a mutually beneficial relationship (known as interdependence) , each helping each other to survive. This microscopic algae is what makes the coral bright and colourful so the removal of the algae leaves the coral white and ‘bleached’. Thousands of marine animals depend on corals for survival, because they provide shelter, spawning grounds and protection from predators such as sharks. Coral bleaching has a huge impact on reef ecosystems because once corals die, reefs rarely come back and therefore they struggle to reproduce as efficiently causing all sorts or reductions in biodiversity. As well as having a huge impact on wildlife, coral bleaching also has a profound impact on humans. Coral reefs act as natural barriers that absorb the force of waves and storm surges, protecting coastal communities. Without them, much land would be at risk of flooding, and this problem will only increase in the future as the occurrence of storm surges becomes more common. Bleaching coral also contributes to the overfishing crisis because it causes more species of fish to decline, so some people may lack a key source of their diet. The tourism industry is also affected enormously by coral bleaching because reef tourism brings in billions of dollars a year as well as providing many local jobs. However people have begun to realise that there are ways of preventing the future of bleaching coral and also combating the bleaching that has already occurred. For example in Moorea, French Polynesia, the nonprofit group Coral Gardeners tends broken pieces of coral on a nursery table for one month before reattaching them to reefs. Travelers there can adopt a coral piece and help the group plant it in efforts to help restore reef habitats.

As the concentrations of carbon dioxide in the atmosphere are increasing, the ocean absorbs more and more of it making them become more acidic. This increased acidity has a profound impact on marine ecosystems that rely on oxygen because as the CO2 concentrations in the water increase, it becomes increasingly difficult for gilled marine animals to extract the oxygen and breathe. Another impact that acidic oceans have on ecosystems is that creatures that rely on shells for survival such as crabs and lobsters may find it more difficult to build their shells (which are made from calcium carbonate) and the shells may even begin to dissolve if they cannot withstand the acidity. This lack or weakening of marine creature’s shells impacts ecosystems because they become easier targets for predators and therefore may reduce drastically in numbers. This will have a knock-on effect on any ecosystem they are involved in because all types of plants and animals within an ecosystem are reliant on one another for survival.

Rising temperatures around the globe have also led to a rise in sea levels. Global warming (which is occurring as a result of the excessive volumes of greenhouse gases humans are releasing into the atmosphere) causes ice in polar regions to melt and also causes thermal expansion. This combination of a larger volume of water in the oceans and the water molecules which have expanded due to the increased temperature means that sea levels around the globe have risen.  Rising sea levels will have serious impacts on all types of marine ecosystems. For example a marine ecosystem which is especially susceptible to rising sea levels are mangrove ecosystems because they rely on stable sea levels for survival. Similarly rising water levels will impact many coastal habitats with flooding, and the amount of light reaching offshore plants such as algae will be reduced because there will be a larger volume of water above them and therefore an increased distance for the light to travel. This can reduce the rates of photosynthesis and can lead to many plant and algae species dying out which can have knock on effects due to it acting as the ‘producer’ in many food chains.

Polar ice is vital to many polar species such as polar bears, seals and walruses because it acts as a place to rest, a breeding ground, and a feeding ground. Without it many species may start to disappear because there is no longer a place for them to reproduce and bring up their young.  A species particularly at risk to the melting of polar ice is the polar bear. Melting ice forces polar bears to swim longer distances in search of food for them and their cubs, decreasing their body condition through excessive exercise. Also the food becomes harder to access because their main food source is the seal whose population is also declining with the loss of sea ice. This causes many polar bears to starve and is one of the main factors why polar bears are classified as an endangered species.This melting polar ice also causes the distribution of polar bears to change because they will travel to areas with more ice, however these may be human occupied areas. This can lead on to many issues because animals may begin to rely on humans for essential food sources and it also poses the risk of animal attacks, particularly with carnivorous animals like polar bears which may see humans themselves as a suitable prey.

As certain areas of the ocean warm, particular locations may become ideal and lead to species migrating or moving to different places. Overall, marine species are responding to warmer temperatures by moving northward or deeper when possible in search of cooler waters.  These changes in distribution of marine species not only have huge environmental effects, but also economic ones. For example some economically important species such as the American lobster, red hake and Black Sea bass have shifted locations meaning that fishermen were no longer able to catch and sell these species, or have to travel much further distances to be able to. This shift in the location of thousands of species has a detrimental effect on the ecosystems within the ocean because all the plants and animals are reliant on one another and rely on interdependence for survival.

Following this information it has become clear that marine life does in fact heavily depend on the extent of climate change and its future is dependent upon it. There is a strong correlation between climate change and issues in the ocean, and these problems will only continue to worsen if nothing is done. The impacts that global warming and climate change can induce are significant on marine life because the likelihood is if one species is affected, all the other species will because they are all interconnected through the system of interdependence.