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<p>Freshwater crayfish are increasingly threatened by habitat degradation, declining water quality, and invasive species. In Aotearoa New Zealand, lake populations of the endemic northern freshwater crayfish <i>Paranephrops planifrons</i> (kōura) have declined by up to 91%. Identifying key habitat requirements is essential to improve the conservation of crayfish facing multiple threats. To assess littoral habitat associations, we surveyed shoreline habitats in five Aotearoa lakes and modelled kōura occupancy, abundance, and biomass using generalised additive mixed models. Kōura occupancy increased with shoreline habitat complexity, particularly coarser substrate types and greater riparian vegetation cover. Elevated summer surface water temperatures were negatively associated with kōura occupancy and abundance, indicating reduced habitat suitability during warm periods. pH was positively correlated with kōura abundance and biomass. Our results suggest that the composition and physical structure of littoral habitats are important drivers of kōura distribution and abundance. As climatic drivers resulting in warmer water temperatures and reduced dissolved oxygen are difficult to manage, targeted protection and restoration of coarse substrate shoreline habitats may provide a practical conservation response.</p>

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Littoral habitat structure influences freshwater crayfish populations in five volcanic lakes of Aotearoa New Zealand

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月9日

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  • Olivier V. Raven,
  • Francis J. Burdon,
  • Ian A. K. Kusabs,
  • Robin Holmes,
  • Deniz Özkundakci

摘要

Freshwater crayfish are increasingly threatened by habitat degradation, declining water quality, and invasive species. In Aotearoa New Zealand, lake populations of the endemic northern freshwater crayfish Paranephrops planifrons (kōura) have declined by up to 91%. Identifying key habitat requirements is essential to improve the conservation of crayfish facing multiple threats. To assess littoral habitat associations, we surveyed shoreline habitats in five Aotearoa lakes and modelled kōura occupancy, abundance, and biomass using generalised additive mixed models. Kōura occupancy increased with shoreline habitat complexity, particularly coarser substrate types and greater riparian vegetation cover. Elevated summer surface water temperatures were negatively associated with kōura occupancy and abundance, indicating reduced habitat suitability during warm periods. pH was positively correlated with kōura abundance and biomass. Our results suggest that the composition and physical structure of littoral habitats are important drivers of kōura distribution and abundance. As climatic drivers resulting in warmer water temperatures and reduced dissolved oxygen are difficult to manage, targeted protection and restoration of coarse substrate shoreline habitats may provide a practical conservation response.