Living in a Niche

Waimanga stream habitat

Array of geothermal habitats in a stream at Waimangu. Each colour indicates an environmental niche supporting different microbial life. Photo Credit: Matthew Stott.

Microorganisms, insects and plants have made geothermal areas their home by adapting to extremes of temperature, acidity and alkalinity, turbidity and toxicity. The unique ecosystem biodiversity is so closely linked to chemical and physical conditions within each niche that community composition can vary between neighbouring hot springs, or even within a single pool or at different soil depths.

Where do they come from?

Some species and communities are endemic, that is, they are found only in these habitats and locations.

Many of the plant, insect and larger species are now uniquely adapted for life in geothermal areas and are exclusively found in these extreme habitats. Other opportunistic species have adapted to tolerate geothermal conditions but are also found in non-geothermal areas.

The distribution and diversity of microorganisms within geothermal areas is thought to be a consequence of physical dispersal by air, water, earth, and animals; natural selection to the environmental conditions, and beneficial DNA mutation by the species.

The Geothermal Food Web

Microorganisms are the backbone of the food web in all geothermal ecosystems, but even more so in environments where conditions do not allow photosynthesis. In these cases, microorganisms can use gases, such as methane and hydrogen sulphide, or metals, such as iron or arsenic, as energy sources.

Geothermal food web

Other microorganisms are decomposers, with the ability to recycle nutrients from other organisms’ waste or break down plant material for energy and carbon. In turn, these primary producing microorganisms can be predated by other organisms in the food web.

Grazing insects such as shore flies and midges are found in abundance living and feeding on microbial mats (up to 50°C). Predatory insects live on the cooler edges of hot springs and streams and feed on the larvae and other detritus. The adult geothermal-living insects then become prey for land-based predatory insects and birds.