Environmental drivers of Atrina zelandica habitat suitability in Tauranga Harbour

Abstract

Fan shells (Family Pinnidae) have high ecological importance but are facing global declines including in New Zealand. Given the scarcity of data regarding the degree of these losses, understanding current population spatial extents and distributional drivers is needed for restoration management. A subtidal towed underwater camera survey was conducted at 62 sites to elucidate Atrina zelandica extent in Tauranga Harbour, Bay of Plenty. We observed sparse populations (occurrences at 12 sites, densities −2 ), indicating harbour‐wide declines compared to historical records. Habitat suitability modelling was used to identify possible environmental drivers influencing Atrina and predict areas suitable for restoration. The model performed well (AUC = 0.85) and predicted large areas of high habitat suitability (probability of occurrence > 0.6). Mud content (7–35%), maximum current speed ( −1 ), sediment organic matter ( −3 ) were identified as the key drivers of predicted habitat suitability. Absence of Atrina from areas of high predicted suitability and historical occupancy indicates other factors are restricting recovery. Ongoing destructive benthic activities, alongside Allee effects may be hindering natural recovery, necessitating active restoration and stressor removal to reestablish populations.

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