EXECUTIVE SUMMARY

Cawthron Institute (Cawthron) was commissioned by the Marlborough District Council (MDC) to undertake state of the environment monitoring of the Wairau Estuary. This comprised an assessment of estuary condition or ‘health’ following the standardised Estuary Monitoring Protocol (EMP) (Robertson et al. 2002) and involved two ‘point in time’ surveys of the estuary based on:

(1) Broad-scale vegetation and structural class habitat mapping (baseline for 2015) - with the additional trial use of a drone for aerial photography.

(2) Fine-scale benthic surveys based on a suite of seabed characteristics at three reference sites within the estuary (baseline for 2015).

Further funding (Envirolink 1588-MLDC105) allowed Cawthron to gather local reminisces of the Wairau Estuary from local community members.

The estuary monitoring provided a reference point from which to assess future changes within the Wairau Estuary and to compare against other New Zealand estuaries. Reminisces from local community members provided a valuable context for interpretation of this baseline. Implications for the overall condition or ‘health’ of the Wairau Estuary are discussed and recommendations are made for ongoing monitoring. This information will be incorporated into an estuarine monitoring programme as part of the MDC coastal monitoring strategy (Tiernan 2012).

SUMMARY OF THE CONDITION OF THE WAIRAU ESTUARY

Based on the EMP indicators of estuarine condition, and in comparison with the other New Zealand and overseas estuaries, the Wairau Estuary is exhibiting signs of being in a fair to compromised environmental condition. Together, the results and historic perspectives indicate key estuary functions and values have been undermined. However, these findings should ultimately be considered in context to the ‘choked’ lagoon nature of the Wairau Estuary, which may be naturally attributed with characteristics and functions that vary from those associated with New Zealand estuaries typically assessed using the EMP. This is based on the following key findings that relate to estuarine condition.

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