What are ecosystems?

Ecosystems are bubbles of life. They arise when weather, landscape, plants, animals, and other organisms all work together to form an interactive system. Ecosystems contain biotic (living) parts, like plants and animals, and abiotic (non-living) parts, like rocks and precipitation.

Ecosystems are complex systems in that all of the parts depend on each other to some extent. For example, a change in the soil composition of a forest will affect which plants grow there. Any forest-dwelling animal which depends on plants for shelter or food must adapt, move to another ecosystem, or die.

Some ecosystems are tiny (e.g. a fallen log) and some are vast (e.g. the Amazon rainforest). In fact, the entire surface of Earth is a series of connected ecosystems. This is similar to the way in which big cities, like London, aren’t homogenous metropolises but are actually made up of lots of different neighbourhoods. Most ecosystems are connected in large stretches of land, sea, or atmosphere known as biomes. Think about a beach, which is home to rock pools, sand dunes, the ocean shore, and so on.

Malaria: an ecological problem

Malaria is usually thought of as a medical problem to be tackled using drugs, nets, insecticides and, nowadays, gene editing. But malaria is also an ecological problem.

Mosquitoes are not static, unchanging targets. They move around and mate, breeding in some areas but not others. Their populations grow and shrink throughout the year. They bite at different times of day. Some species stay where they are, others travel. Different species within the same ecosystem exhibit completely different behaviour.

All of this means that mosquito ecology and biology remain somewhat of a black box to scientists – there’s a huge amount that we just don’t understand yet. Studies that make steps towards unravelling their complex ecology are highly valuable and could have big implications for our efforts in tackling malaria.

Contemporary research often involves hunting mosquitos during the dry season, when their populations are at their lowest. This might seem counterintuitive, going after the rarest mosquitoes, but these are the mosquitoes able to mysteriously survive in arid conditions when they simply shouldn’t be able to. They’re the seeds of the huge population boom that comes with the wet season, where numbers surge up to 90x within days. If we’re able to intervene upon mosquito populations during the dry season – which are usually highly concentrated – our impact could be significant.

The role that ecosystems play in aiding or hindering the spread of malaria cannot be understated. It’s important to bear this in mind when thinking about global warming and the planet’s future. Climate change is helping to rapidly expand the ecosystems of mosquitos, bringing with it a new generation of mosquito-borne illnesses (Zika and Chikungunya were first identified in humans only in 1952). One study estimates that one-billion more people could be exposed to mosquito-borne infections within the next fifty years.

Any long-term interventions hoping to reduce rates of malaria cannot ignore the unique relationship between mosquitoes and their ecosystems. It may not be as exciting as gene editing, but understanding ecology and the subtle quirks of mosquito life is tantamount to knowing how to tackle the problem.