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The Sydney region has been modified by urbanisation and human activities. This has resulted in a loss of ecosystem integrity and consequently degraded water quality in aquatic environments. Disturbance of these aquatic environments has a knock on effect to the abundance and diversity of freshwater macroinvertebrate communities across the Sydney region.
An intact macroinvertebrate community is a key component of a healthy aquatic ecosystem. Energy and nutrients which support life within a waterbody, are released into higher levels of the food web via macroinvertebrates.
Ecologists have found that there is a strong relationship between landscape disturbance and changes to the composition of aquatic flora and fauna communities. Some aquatic macroinvertebrates have been shown to be very sensitive to certain types of environmental change. This sensitivity can be helpful to scientists, researchers and landscape managers in identifying which waterbodies are being impacted by land-use practices. Conversely, the same information can be used to identify catchments where land management or urban development may not be occurring in a sustainable way.
Freshwater macroinvertebrate sampling can be a very useful tool when performing a bio-assessment of a site. Biological information can be combined with water quality data to strengthen our ability to assign a relative health ranking to sampling sites. The more lines of evidence, the greater the confidence in assigning a ranking. Ultimately, this will culminate in producing a map identifying the good, the bad and the ugly across the Sydney region.
Because waterbugs spend all or part of their life cycles in water, they are exposed and subject to local water quality conditions, over a period of time. It is this dependency and exposure to water chemistry that makes them useful as indicators.
Ongoing sampling at least twice a year will be very helpful in developing more robust stream health data, when carried out in conjunction with water quality monitoring. It will also assist in identifying environmental change over time.
Waterbug Watch has adopted a easier way of sampling freshwater macroinvertebrates using an EPT Index as a scoring system that focuses on three macroinvertebrate orders known to have a significant number of sensitive members (many-not all). It is a simple metric, useful in rapid bio-assessment as it does not require identifying all taxa, yet still provides valuable information. A percentage value is established for a site from the number of sensitive taxa Ephemeroptera (mayfly), Plecoptera (stonefly), and Trichoptera (caddisfly) present in a sample, divided by the total number of taxa collected, this is then multiplied by 100.
Citizen Science is a powerful way to collect and analyse data in the pursuit of greater scientific knowledge. Waterbug Watch was trialled in 2014 with Streamwatch groups across Sydney and the Australian Museum intend to extend on the program in 2015.