ECOSYSTEM HEALTH ASSESSMENT

ARE URBAN FISH AND SHELLFISH SAFE TO EAT?
Service Areas: Ecosystem Health Assessment, Urban Ecology, Science Communication, Photographic Resources

Is it safe to eat the fish and shellfish in our urban rivers and estuary? This was a question that Environment Canterbury (ECan) wanted answered as part of their ‘healthy rivers and estuary’ programme. Since 2008 ECan has commissioned EOS Ecology to monitor the levels of heavy metals in estuary fish (yellow-eyed mullet, flounder) and shellfish (cockles, pipis), as well as shortfin eels in Christchurch’s two iconic rivers; the Avon and Heathcote. In 2019 they also asked EOS to monitor E.coli levels in cockles from the estuary and PCBs in fish.

Under their MPI research permit, the EOS team uses a range of sampling techniques involving netting, boating and hand collection to gather the fish and shellfish for testing. The results are made accessible to the wider public through the production of public-friendly reports that outline the issues and source of contaminants in our wild foods, and the findings as to whether wild food from Ōtautahi/Christchurch’s rivers and estuary is safe to eat.

BANKS PENINSULA STREAM SURVEYS
Service Areas: Ecosystem Health Assessment, Applied Research, Aquatic Sample Processing

EOS Ecology returned to Banks Peninsula in 2014 to survey 13 streams for native fish and freshwater invertebrates. This work is part of a Christchurch City Council project to identify ‘Sites of Ecological Significance’ on Banks Peninsula and the second season EOS Ecology has been involved. The surveys help the City Council to identify streams that are of outstanding ecological value, that may be home to rare or endangered species. The council plans to use this information to find ways to support landowners and communities to protect and enhance key streams, to safeguard the wonderful biodiversity found there. EOS Ecology staff tested their mettle abilities to work in all the challenges the terrain offered; with many steep, narrow slippery waterways.
 

CATCHMENT-WIDE ASSESSMENTS - CASHMERE STREAM
Service Areas: Ecosystem Health Assessment, Science Communication

Cashmere Stream is a tributary of Christchurch’s Heathcote/ Ōpāwaho River with high ecological values, despite having a catchment heavily modified by agricultural and urban development. The stream is home to koura/freshwater crayfish, kākahi/freshwater mussel, several caddisflies, and good fish diversity.

EOS Ecology was asked by Environment Canterbury to produce a public-friendly report that summarised the ecological state, the pressures affecting the ecology, and the responses required to maintain and improve the ecology of Cashmere Stream. Based off information from a range of sources, including years of our own ecology, sediment, and stormwater investigations, this report will help guide management of the catchment by local authorities and allow the catchment’s strong community-based stream care group to focus on the main issues.

 The report is available on Environment Canterbury's campaign website - cleanwaterways.org.nz

EARTHQUAKE EFFECTS ON CHRISTCHURCH’S WATERWAYS
Service Areas: Ecosystem Health Assessment, Applied Research, Aquatic Sample Processing, Urban Ecology, Science Communication

Following the 22 February 2011 earthquake EOS Ecology was asked to investigate the impacts of sewage and sand/silt inputs on Christchurch’s aquatic invertebrates and freshwater fish. For the upper reaches of the Avon River we re-sampled sites for which we had surveyed prior to the earthquake. Assessing the impacts in the non-wadeable sections (lower reaches) of the Avon and Heathcote Rivers was more problematic because of a lack of sufficient pre-earthquake data. This required us to think outside the square and conduct a survival experiment with common aquatic invertebrate species being housed in cages upstream and downstream of sewage inputs in the Avon and Heathcote Rivers. Additionally, some 10 months after the earthquake we conducted the first comprehensive fish and invertebrate survey of the lower, non-wadeable Avon River in over 20 years to determine the current state of the system.

Due to the obvious public interest in these studies our Science Communication department ensured our own full reports, and the final summary publications, were designed to be easily understood and visually stunning. The full reports and summaries are available on ECan’s website. Or you can download the summaries below.

BIOLOGICAL SURVEY OF THE LOWER AVON RIVER
Service Areas: Ecosystem Health Assessment, Applied Research, Aquatic Sample Processing, Urban Ecology, Science Communication

In December 2011 EOS Ecology undertook a comprehensive survey of the aquatic invertebrates and fish of the lower, non-wadeable Avon River. Set against the backdrop of the 22 February earthquake some 10 months earlier, this was the first survey of either fish or invertebrates in this part of the river in over 20 years. The challenging conditions of deep (non-wadeable) water required specialist equipment and boats to sample the fish and invertebrate community.

Our survey provides vital data on the current state of the fauna to help predict the impacts of proposed earthquake-related activities and developments along this stretch of river (e.g., dredging, bank works, construction of rowing lake). Because the general public have great interest in the state of their river, our Science Communication team crafted an attractive, easy to understand report, which is available on ECan’s site or by download below.

CITYWIDE INVERTEBRATE MONITORING
Service Areas: Ecosystem Health Assessment, Aquatic Sample Processing, Urban Ecology

To gain a better understanding of the changing state of waterway health in Christchurch, the Christchurch City Council has commissioned EOS Ecology to develop and implement a long-term citywide invertebrate sampling programme since 2008.

Involving the collection of invertebrate samples and habitat information at many sites, the project encompasses the catchments of each of the five main river systems within the Christchurch City boundary - Avon, Heathcote, Styx, Otukaikino, and Halswell. Sampling each river system on a five yearly rotation will provide data on a range of catchment land-use types from fully urban through to predominantly rural and will allow comparisons of aquatic invertebrate communities across catchments and over time.

Aimed at a non-scientific audience, reports are written in a public-friendly format with a more science-focused report comparing the river systems to be written at the end of each five-year sampling period.