title: Quantifying relationships between kōura  (Paranephrops planifrons) abundance and micro-habitat features in Waikato hill-country streams

authors: Parata, Riki Neihana

subjects: kōura

abstract: Kōura (Paranephrops planifrons) is considered a taonga species by Māori and was once an abundant traditional fishery harvested throughout New Zealand. Kōura populations are under pressure in Waikato hill-country streams due to a range of factors including habitat loss and water quality degradation. Now that stakeholders have been engaging in collaborative decision-making and practices to restore/enhance biodiversity and ecosystem health within the Waikato catchment, there is opportunity to implement measures specifically targeted at kōura. Information on kōura habitat requirements to assist with the development of habitat enhancement work is therefore timely.
This research comprised two discrete studies which, in combination, provide important insights into daytime habitat use by kōura in Waikato hill-country streams. The first study was a field survey that examined in-stream habitat characteristics affecting kōura density and size, with a focus on juveniles ≤ 8 mm orbital carapace length (OCL), across a range of scales ranging from habitat patches to streams with contrasting catchment and riparian vegetation treatments – pasture, early or late riparian planting, and native forest. Micro-habitat variables related to kōura density included water depth and velocity, substrate size, and the area of bank undercuts and organic cover types, with root mat area significantly and positively related to juvenile densities across all scales. Although there was no significant effect of treatment type, there were strong associations between kōura and ponga logs, root systems, and coarse particulate organic matter (CPOM) across scales within and between streams.
The second study was a habitat manipulation experiment conducted to investigate whether kōura abundances, in particular juveniles, could be enhanced by additions of organic habitat consisting of 0.5 m² coconut fibre matting to simulate ponga (Cyathea dealbata) root systems that occur on the stream bank, and 1 m² ponga frond bundles to simulate the natural habitat structures formed in native forested areas. These two artificial habitats were compared with natural in-stream cobble habitats. Kōura and toi toi (Gobiomorphus spp.), both showed a preference for ponga frond habitats which were predicted to provide submerged habitat for more than 200 days. Although the coconut fibre matting was predicted to outlast ponga frond bundles by up to 107 days, it was more susceptible to sedimentation and did not provide adequate habitat for kōura due to its dense structure.
This study highlighted the influence of riparian treatments, hydrological processes, and inorganic and organic habitats on kōura populations. Information from this study can provide restoration managers with guidance on how to enhance in-stream and stream edge habitat suitability for kōura and can be used with existing mātauranga Māori, and western and community science, to determine suitable vegetation for riparian planting, assess what factors and drivers contribute to in-stream habitat availability and sustainability, and identify important habitat features that relate to kōura when conducting habitat restoration.

text: Quantifying relationships between kōura  (Paranephrops planifrons) abundance and micro-habitat features in Waikato hill-country streams Kōura (Paranephrops planifrons) is considered a taonga species by Māori and was once an abundant traditional fishery harvested throughout New Zealand. Kōura populations are under pressure in Waikato hill-country streams due to a range of factors including habitat loss and water quality degradation. Now that stakeholders have been engaging in collaborative decision-making and practices to restore/enhance biodiversity and ecosystem health within the Waikato catchment, there is opportunity to implement measures specifically targeted at kōura. Information on kōura habitat requirements to assist with the development of habitat enhancement work is therefore timely.
This research comprised two discrete studies which, in combination, provide important insights into daytime habitat use by kōura in Waikato hill-country streams. The first study was a field survey that examined in-stream habitat characteristics affecting kōura density and size, with a focus on juveniles ≤ 8 mm orbital carapace length (OCL), across a range of scales ranging from habitat patches to streams with contrasting catchment and riparian vegetation treatments – pasture, early or late riparian planting, and native forest. Micro-habitat variables related to kōura density included water depth and velocity, substrate size, and the area of bank undercuts and organic cover types, with root mat area significantly and positively related to juvenile densities across all scales. Although there was no significant effect of treatment type, there were strong associations between kōura and ponga logs, root systems, and coarse particulate organic matter (CPOM) across scales within and between streams.
The second study was a habitat manipulation experiment conducted to investigate whether kōura abundances, in particular juveniles, could be enhanced by additions of organic habitat consisting of 0.5 m² coconut fibre matting to simulate ponga (Cyathea dealbata) root systems that occur on the stream bank, and 1 m² ponga frond bundles to simulate the natural habitat structures formed in native forested areas. These two artificial habitats were compared with natural in-stream cobble habitats. Kōura and toi toi (Gobiomorphus spp.), both showed a preference for ponga frond habitats which were predicted to provide submerged habitat for more than 200 days. Although the coconut fibre matting was predicted to outlast ponga frond bundles by up to 107 days, it was more susceptible to sedimentation and did not provide adequate habitat for kōura due to its dense structure.
This study highlighted the influence of riparian treatments, hydrological processes, and inorganic and organic habitats on kōura populations. Information from this study can provide restoration managers with guidance on how to enhance in-stream and stream edge habitat suitability for kōura and can be used with existing mātauranga Māori, and western and community science, to determine suitable vegetation for riparian planting, assess what factors and drivers contribute to in-stream habitat availability and sustainability, and identify important habitat features that relate to kōura when conducting habitat restoration.

year: 2019

title: E ia, e ia

authors: Maxwell, Te Kahautu

abstract: Poi, Lyrics composed by Te Kahautu Maxwell, Musical score composed by Te Whānau Mitai. Performed by Ōpōtiki Mai Tawhiti (Kapa Haka group) (3mins)

Waiata ā Tira: Aroha
Whakaeke: Pinepine Te Kura, Hau Te Kura
Mōteatea: Te Ao o Te Pārerā
Waiata ā Ringa: E pā to reo, Te Matatini, Herewini Parata
Poi: E ia e ia
Haka: Te Kōtiritiri, Te Kōtaratara
Whakawātea: Ōranga Tōiti, tōnui kōrero

text: E ia, e ia Poi, Lyrics composed by Te Kahautu Maxwell, Musical score composed by Te Whānau Mitai. Performed by Ōpōtiki Mai Tawhiti (Kapa Haka group) (3mins)

Waiata ā Tira: Aroha
Whakaeke: Pinepine Te Kura, Hau Te Kura
Mōteatea: Te Ao o Te Pārerā
Waiata ā Ringa: E pā to reo, Te Matatini, Herewini Parata
Poi: E ia e ia
Haka: Te Kōtiritiri, Te Kōtaratara
Whakawātea: Ōranga Tōiti, tōnui kōrero

year: 2023-02-22

title: Skistodiaptomus pallidus (Copepoda: Diaptomidae) establishment in New Zealand natural lakes, and its effects on zooplankton community composition

authors: Duggan, Ian C.

subjects: boom-and-bust

abstract: The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in late-2008, coincident with releases of domestically cultured grass carp (Ctenopharyngodon idella). Although not present in any of our samples prior to August 2008, S. pallidus was found in all samples collected in the subsequent five years. ANOSIM indicated zooplankton community composition significantly differed between samples collected before and after S. pallidus invasion, whether the invader was included in the analysis or not. Zooplankton species affected most greatly were the copepods Calamoecia lucasi and Mesocyclops sp., which decreased in their relative importance, and the cladocerans Bosmina meridionalis and Daphnia galeata, which increased. Rotifer species were relatively unaffected. As the length of grass carp released were >6.5 cm, direct predatory effects by this species on the zooplankton community are unlikely. Associated reductions in macrophyte biomass could explain increases in the relative abundances of planktonic cladocerans (B. meridionalis and D. galeata). However, the effect of macrophyte reduction by grass carp on zooplankton communities is considered to be limited elsewhere, while the reduced macrophyte biomass cannot explain the decrease in relative abundance of the native planktonic calanoid copepod C. lucasi. Competition between C. lucasi and S. pallidus is the most compelling explanation for the reduction in importance of the native calanoid copepod species. Skistodiaptomus pallidus appears to have undergone a “boom-and-bust” cycle in Lake Kereta, increasing in relative abundance in the first three years following establishment, before declining in importance.

text: Skistodiaptomus pallidus (Copepoda: Diaptomidae) establishment in New Zealand natural lakes, and its effects on zooplankton community composition The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in late-2008, coincident with releases of domestically cultured grass carp (Ctenopharyngodon idella). Although not present in any of our samples prior to August 2008, S. pallidus was found in all samples collected in the subsequent five years. ANOSIM indicated zooplankton community composition significantly differed between samples collected before and after S. pallidus invasion, whether the invader was included in the analysis or not. Zooplankton species affected most greatly were the copepods Calamoecia lucasi and Mesocyclops sp., which decreased in their relative importance, and the cladocerans Bosmina meridionalis and Daphnia galeata, which increased. Rotifer species were relatively unaffected. As the length of grass carp released were >6.5 cm, direct predatory effects by this species on the zooplankton community are unlikely. Associated reductions in macrophyte biomass could explain increases in the relative abundances of planktonic cladocerans (B. meridionalis and D. galeata). However, the effect of macrophyte reduction by grass carp on zooplankton communities is considered to be limited elsewhere, while the reduced macrophyte biomass cannot explain the decrease in relative abundance of the native planktonic calanoid copepod C. lucasi. Competition between C. lucasi and S. pallidus is the most compelling explanation for the reduction in importance of the native calanoid copepod species. Skistodiaptomus pallidus appears to have undergone a “boom-and-bust” cycle in Lake Kereta, increasing in relative abundance in the first three years following establishment, before declining in importance.

year: 2014