Biodiversity

Areas like tropical rainforests have millions of different species and are very biodiverse. Other areas like the Polar Regions have far fewer species and are less biodiverse.

Biodiversity is specifically the number of different species. An area with large populations of few species is not biodiverse.

Ecosystems with higher biodiversity have fewer species that depend on just one other species for food, shelter and maintaining their environment. Ecosystems with higher biodiversity are more stable as they can easily adjust to changes.

We are slowly realising that the future of our species on Earth depends on maintaining high biodiversity. Biodiversity is important for human wellbeing as it provides food, potential foods, industrial materials and new medicines.

Activities that create air and water pollution are reducing biodiversity in many ecosystems. Conservation of species and habitats by charities, governments and individuals helps to maintain the range of biodiversity.

A pangolin
A pangolin

The Pangolin is an endangered species. This means the numbers of Pangolin found in the wild are decreasing and if this continues it may become extinct.

Biodiversity and endangered species can be conserved and protected by:

  • the Convention on International Trade in Endangered Species (CITES)
  • sites of special scientific interest
  • captive breeding programmes
  • National Parks
  • seed/sperm banks
  • local biodiversity action plans

These forms of conservation and protection are local, national and international. Much of this work depends upon dedicated volunteers. Other examples such as the protection of land as National Parks, depends upon governments. This requires legislation which can take time to pass into law - governments need to use reliable sampling data, often from ongoing monitoring, to do this. It is often challenging for all parties to weigh up whether protection of species and ecosystems is more or less important than other priorities such as healthcare and infrastructure like roads and schools.

Biological control and alien species

In Australia in the 1930s, farmers had a real problem with beetles and grubs eating the sugar cane they were trying to grow. It was decided that pesticides might also harm other native species so instead they decided to try biological control.

The cane toad from Hawaii was introduced to Queensland in the hope it would eat the pests that the farmers were struggling with.

Unfortunately, the cane toad was:

  • an alien species to Australia - it had no natural predators to control its numbers and as a result its population exploded
  • a predator of a large variety of organisms, but not the cane beetle it was hoped they would control
  • prey for many predators, but it is protected by a toxin which killed many of its predators

This series of events led to a large reduction of biodiversity in the area, reducing the population of the yellow-spotted monitor lizard by 90%. To this day, Australia is struggling to control the spread of this invasive species.

Indicator species

Indicator species are organisms whose presence or absence tells us about the condition of the environment. Often indicator species tell us about the levels of pollution in an area.

Oxygen dissolves in water. This comes from the oxygen in the air and that which is produced when plants photosynthesise. Without this, aquatic animals would suffocate and die. Healthy lakes and rivers have high levels of oxygen. However, polluted waters often have low levels of oxygen. This pollution means that only certain species can survive there such as sludgeworms. These are indicator species of polluted water. Reversely, the presence of delicate species like mayfly nymphs indicates water without pollution.

Lichens are amazing organisms in which a fungus and bacterium live together. They are also indicator species of air pollution. In areas with crusty or no lichens, the air pollution is high or very high. In areas with larger, bushier lichens, the air pollution is lower.

Clean: stonefly nymph, mayfly larva. Some pollution: freshwater shrimp, caddis fly larva. Moderate: bloodworm, water louse. High: sludgeworm, red-tailed maggot.  Very high: no living insects.