Whaitua Te Whanganui-a-Tara. Coastal habitat vulnerability and ecological condition
- Author
- Stevens, L.M.
- Year
- 2018
- Journal / Source
- Salt Ecology Report 004 prepared for Greater Wellington Regional Council.
- Pages
- 50 pp
- Summary
- In order to support the effective monitoring and management of coastal and estuarine ecological features throughout the Wellington region, Greater Wellington Regional Council (GWRC) has previously commissioned investigations to characterise coastal and estuarine habitats and assess broad scale risks to these habitats from human activities. To support the current Wellington/Hutt whaitua process, this existing work has been reviewed and updated by quickly re-assessing the existing coastal habitat maps of the Wellington/Hutt whaitua and reviewing whether there were any obvious changes to stressors previously identified in relation to the three major coastal habitat types (rocky shores, sandy beaches and estuaries). The reassessment identified several minor changes where seawalls had been constructed or repaired, but overall confirmed that the type and impact of previously identified coastal stressors had not changed significantly over the past decade. More detailed assessments of representative sandy beach, rocky shore and estuarine areas have been undertaken to characterise the general state of these important habitat features. McMurtrie and Brennan (2016) reported the community composition of Eastern Bays intertidal inner harbour sites was typical of rocky shore and beach habitat in the region. Stevens (2018a) found Petone Beach, Lyall Bay and Owhiro Bay to be in “very good” or “good” condition overall, and rocky shore sites representing a spectrum of wave exposures at Makara, Scorching Bay and Baring Head to be typical of “healthy” New Zealand rocky shores and similar to that described from previous surveys conducted at Flat Point on the Wairarapa coast (Stevens 2018b). Assessments undertaken in Makara, Kaiwharawhara, Korokoro, Hutt and Wainuiomata estuaries provided updated habitat maps and detail on current condition. While estuaries are some of the most significantly modified coastal habitats in the whaitua, they retain high human use and ecological values because of their regional scarcity. Makara was in a relatively poor condition due to restricted flushing and elevated sediment and nutrient inputs. Kaiwharawhara, Korokoro, and Hutt estuaries were in a moderate ecological state, primarily maintained by high flushing but greatly modified by past channelisation. Wainuiomata Estuary was in good condition but is highly sensitive to sediment and nutrient inputs due to long periods of mouth closure. The relative rarity of estuarine habitat in the region, combined with extensive past modification, means remaining habitat is very important and should be protected from further degradation, and enhanced wherever possible.