The cartoon is headed 'Whitebait - How to spot the difference.' Below are two frames; the one on the left shows a brown fish wearing goggles and breathing apparatus, it is from the East Coast and is described as 'drab brown' and 'tastes like dung'; the one on the right is pink and wears a sun hat and sunglasses, it is from the West Coast and is described as 'lightly tanned' and 'tastes like coconut'. Context: The whitebait from the east coast has been contaminated by the Canterbury earthquakes.
Quantity: 1 digital cartoon(s).
The cartoon shows a platter of 'Brownbait patties $2 per kilo'. In the background is a 'contaminated' river. Refers to the contamination of Canterbury's waterways after the earthquake of 4th September which resulted in sewage pipes being damaged thus contaminating the rivers. This means that people should not be attempting to catch whitebait in these rivers during the annual whitebait season which is open between 15 August and 30 November.
Quantity: 1 digital cartoon(s).
The Canterbury earthquakes resulted in numerous changes to the waterways of Ōtautahi Christchurch. These included bank destabilisation, liquefaction effects, changes in bed levels, and associated effects on flow regimes and inundation levels. This study set out to determine if these effects had altered the location and pattern of sites utilised by īnanga (Galaxias maculatus) for spawning, which are typically restricted to very specific locations in upper estuarine areas. Extensive surveys were carried out in the Heathcote/Ōpāwaho and Avon/Ōtākaro catchments over the four peak months of the 2015 spawning season. New spawning sites were found in both rivers and analysis against pre-earthquake records identified that other significant changes have occurred. Major changes include the finding of many new spawning sites in the Heathcote/Ōpāwaho catchment. Sites now occur up to 1.5km further downstream than the previously reported limit and include the first records of spawning below the Woolston Cut. Spawning sites in the Avon/Ōtākaro catchment also occur in new locations. In the mainstem, sites now occur both upstream and downstream of all previously reported locations. A concentrated area of spawning was identified in Lake Kate Sheppard at a distinctly different location versus pre-quake records, and no spawning was found on the western shores. Spawning was also recorded for the first time in Anzac Creek, a nearby waterway connected to Lake Kate Sheppard via a series of culverts.
Coastal margins are exposed to rising sea levels that present challenging circumstances for natural resource management. This study investigates a rare example of tectonic displacement caused by earthquakes that generated rapid sea-level change in a tidal lagoon system typical of many worldwide. This thesis begins by evaluating the coastal squeeze effects caused by interactions between relative sea-level (RSL) rise and the built environment of Christchurch, New Zealand, and also examples of release from similar effects in areas of uplift where land reclamations were already present. Quantification of area gains and losses demonstrated the importance of natural lagoon expansion into areas of suitable elevation under conditions of RSL rise and showed that they may be necessary to offset coastal squeeze losses experienced elsewhere. Implications of these spatial effects include the need to provide accommodation space for natural ecosystems under RSL rise, yet other land-uses are likely to be present in the areas required. Consequently, the resilience of these environments depends on facilitating transitions between human land-uses either proactively or in response to disaster events. Principles illustrated by co-seismic sea-level change are generally applicable to climate change adaptation due to the similarity of inundation effects. Furthermore, they highlight the potential role of non-climatic factors in determining the overall trajectory of change. Chapter 2 quantifies impacts on riparian wetland ecosystems over an eight year period post- quake. Coastal wetlands were overwhelmed by RSL rise and recovery trajectories were surprisingly slow. Four risk factors were identified from the observed changes: 1) the encroachment of anthropogenic land-uses, 2) connectivity losses between areas of suitable elevation, 3) the disproportionate effect of larger wetland vulnerabilities, and 4) the need to protect new areas to address the future movement of ecosystems. Chapter 3 evaluates the unique context of shoreline management on a barrier sandspit under sea-level rise. A linked scenario approach was used to evaluate changes on the open coast and estuarine shorelines simultaneously and consider combined effects. The results show dune loss from a third of the study area using a sea-level rise scenario of 1 m over 100 years and with continuation of current land-uses. Increased exposure to natural hazards and accompanying demand for seawalls is a likely consequence unless natural alternatives can be progressed. In contrast, an example of managed retreat following earthquake-induced subsidence of the backshore presents a new opportunity to restart saltmarsh accretion processes seaward of coastal defences with the potential to reverse decades of degradation and build sea-level rise resilience. Considering both shorelines simultaneously highlights the existence of pinch-points from opposing forces that result in small land volumes above the tidal range. Societal adaptation is delicately poised between the paradigms of resisting or accommodating nature and challenged by the long perimeter and confined nature of the sandspit feature. The remaining chapters address the potential for salinity effects caused by tidal prism changes with a focus on the conservation of īnanga (Galaxias maculatus), a culturally important fish that supports New Zealand‘s whitebait fishery. Methodologies were developed to test the hypothesis that RSL changes would drive a shift in the distribution of spawning sites with implications for their management. Chapter 4 describes a new practical methodology for quantifying the total productivity and spatiotemporal variability of spawning sites at catchment scale. Chapter 5 describes the novel use of artificial habitats as a detection tools to help overcome field survey limitations in degraded environments where egg mortality can be high. The results showed that RSL changes resulted in major shifts in spawning locations and these were associated with new patterns of vulnerability due to the continuation of pre-disturbance land-uses. Unexpected findings includes an improved understanding of the spatial relationship between salinity and spawning habitat, and identification of an invasive plant species as important spawning habitat, both with practical management implications. To conclude, the design of legal protection mechanisms was evaluated in relation to the observed habitat shifts and with a focus on two new planning initiatives that identified relatively large protected areas (PAs) in the lower river corridors. Although the larger PAs were better able to accommodate the observed habitat shifts inefficiencies were also apparent due to spatial disparities between PA boundaries and the values requiring protection. To reduce unnecessary trade-offs with other land-uses, PAs of sufficient size to cover the observable spatiotemporal variability and coupled with adaptive capacity to address future change may offer a high effectiveness from a network of smaller PAs. The latter may be informed by both monitoring and modelling of future shifts and these are expected to include upstream habitat migration driven by the identified salinity relationships and eustatic sea-level rise. The thesis concludes with a summary of the knowledge gained from this research that can assist the development of a new paradigm of environmental sustainability incorporating conservation and climate change adaptation. Several promising directions for future research identified within this project are also discussed.
