URBAN ECOLOGY

FISH RESCUES FROM SEDIMENT
Service Areas: Urban Ecology

Over 3000 tonnes of sediment was removed from the Ōtākaro/Avon River between Montreal and Colombo Street This work was carried out by City Care, as part of the CERA/CCDU-led Te Papa Ōtākaro/Avon River Precinct (ARP), a key anchor project in the Christchurch rebuild following the devastating earthquakes.

EOS Ecology was on hand to rescue fish as part of this process, with 254 fish removed from the river and released upstream before sediment removal was carried out.

Another 334 were rescued from the removed sediment. Fine sediment (sand, silt, mud) removed from the Ōtākaro/Avon River was temporarily stored in a stockpile on the south-east corner of Armagh and Manchester streets. If it was wet enough to fish, an electrofishing machine was used to draw fish up through the sediment. The fish collected were released back to the Ōtākaro/Avon River in suitable habitat upstream of the works area.

COCKLE PATHOGEN MONITORING
Service Areas: Urban Ecology, Ecosystem Health Assessment

Commissioned by Christchurch City Council to monitor shellfish pathogen levels in the Avon-Heathcote Estuary/Ihutai, EOS has been collecting and testing cockles from six sites in the estuary and two control sites further north on a quarterly basis since 2008. Regular reports help identify any risks to public health from this popular recreational fishery.

Used in conjunction with water quality testing, our monitoring was particularly useful after the 2011 Christchurch earthquakes – when cockle monitoring was used to track food safety risks following unprecedented sewage discharges into the city’s rivers and estuary. Working in this testing environment brought about new sets of challenges for our staff, with their health and safety being paramount.

AVON-HEATHCOSTE ESTUARY/IHUTAI MONITORING
Service Areas: Urban Ecology, Ecosystem Health Assessment, Aquatic Sample Processing

After developing a long-term monitoring programme for the Avon-Heathcote Estuary/Ihutai that aligns with national monitoring programmes, EOS Ecology has been monitoring the health of the Estuary for the Christchurch City Council since 2007.

Designed to identify changes in sediment contamination and nutrient levels, macroaglae cover, and the health of invertebrates living on and in the estuary sediment, the EOS team has been undertaking annual surveys at six sites within the estuary and its rivermouths. Our data forms the basis for Environment Canterbury’s reporting for the ‘healthy rivers and estuary’ programme, that is a joint effort between them and Christchurch City Council. Our survey work following the Christchurch February 2011 earthquakes will also help track recovery from these unprecedented seismic events.

MOSQUITOES IN STORMWATER SUMPS
Service Areas: Urban Ecology, Applied Research, Aquatic Sample Processing

Roadside stormwater sumps not only trap sediment but can be a potential haven in otherwise unsuitable areas for mosquito larvae. The team at EOS Ecology developed a unique sampling methodology to assess the suitability of these sumps as mosquito habitats and to determine population densities within Christchurch.

Sampling over 800 sumps across five Christchurch suburbs, the EOS team processed samples to count and identify mosquito larvae species with the potential to carry diseases to birds or humans. The data collected from this study will allow us to determine how important roadside sumps are as habitats for mosquitoes, pinpoint breeding hotspots, and determine what makes a sump so attractive to them.