Initial Impacts

Soon after the earthquake MERG began re-surveying our long-term research sites that span the coast. Many of these sites have been monitored for over 20 years. These surveys gave us a good understanding of the immediate impacts on coastal habitats and species. This work also provided a great foundation for our post-earthquake research. The following sections provide a snapshot of some important changes that resulted from the Kaikōura earthquake.

Coastal fishes & invertebrates

By chance, the earthquake happened to coincide with a high tide. This meant increased devastation to marine animals that inhabited the intertidal zone during this time. Around big uplift areas such as Waipapa, coastal fishes such as butterfish (Odax pullus) and wrasses (Notolabrus fucicola and N. celidotus) were scattered over the uplifted reefs, left high and dry. Lobsters and several species of snails (cat’s eye Lunella smaragdus and Cook’s turban Cookia sulcata) were also found
dead around the reef at Waipapa. The impact of this scale of reef community death is huge. Water quality became extremely poor in tide pools and around the new low intertidal zone due to oxygen levels dropping to or below the minimum for supporting life.

Paua

Along the coastline, paua mortality from the earthquake was high. At some sites the uplift caused thousands of paua to be exposed, many of which were greater than the minimum harvestable size. Even more crucial was the loss of settlement and recruitment habitat for juvenile paua. Over the last few years research into juvenile paua populations along the coast has led to the identification of several ‘hot-spots’ for paua recruitment. Our next round of research will be focussing on these areas as well as the fate of juvenile paua in general. This information will be very important for understanding longer term impacts on paua along the coast and implications for reopening the fishery.

Seaweeds

The seaweed gardens that are a distinctive feature of Kaikōura’s coastline have suffered major impacts. Many large habitat forming species such as bull kelp were left exposed on stretches of uplifted reef (Figure 1). On Kaikōura Peninsula, previously flourishing intertidal communities characterised by Neptune’s necklace (Hormosira banksii) perished over large areas due to uplift effects (Figure 2). Since the earthquake, algal blooms of species such as sea lettuce (Ulva lactuca), have been common in the intertidal zone. This has likely been assisted by the absence of grazing invertebrates. In combination, this amounts to a set of complex changes that are still occurring along the coast. Unravelling these events and the implications on other species will be a key focus for RECOVER.