title: Wetland biodiversity in Aotearoa New Zealand: an eDNA perspective on exotic and non-exotic species

authors: Bird, Starsha

abstract: Invasive species threaten biodiversity in Aotearoa New Zealand. In wetlands − significant sites that provide an array of ecosystem and cultural services but represent <10% of their original extent − invasive species can affect hydrological function, nutrient regimes and overall ecological functionality. Environmental DNA (eDNA) has emerged as a valuable biomonitoring technique for cataloguing biodiversity and detecting biological incursions, but little is known about how biodiversity varies in wetlands over fine and broad spatial scales. Here, we examined the publicly available eDNA database of Wilderlab New Zealand, retrieving data from 26 sites across the country to characterise taxonomic diversity patterns, including the extent of exotic and non-exotic (native and endemic) species. We found significant spatial variation in biodiversity–even among neighbouring sites–and a pattern whereby all sites had ≥50% exotic species in their total species tally. Our results provide new information on the current state of wetland biodiversity in Aotearoa New Zealand and highlight the value of eDNA databases for generating new insights from publicly shared data. They also emphasise an urgent need for greater resource allocation to conservation and restoration initiatives in Aotearoa New Zealand that will ensure the persistence of treasured native and endemic wetland species.

text: Wetland biodiversity in Aotearoa New Zealand: an eDNA perspective on exotic and non-exotic species Invasive species threaten biodiversity in Aotearoa New Zealand. In wetlands − significant sites that provide an array of ecosystem and cultural services but represent <10% of their original extent − invasive species can affect hydrological function, nutrient regimes and overall ecological functionality. Environmental DNA (eDNA) has emerged as a valuable biomonitoring technique for cataloguing biodiversity and detecting biological incursions, but little is known about how biodiversity varies in wetlands over fine and broad spatial scales. Here, we examined the publicly available eDNA database of Wilderlab New Zealand, retrieving data from 26 sites across the country to characterise taxonomic diversity patterns, including the extent of exotic and non-exotic (native and endemic) species. We found significant spatial variation in biodiversity–even among neighbouring sites–and a pattern whereby all sites had ≥50% exotic species in their total species tally. Our results provide new information on the current state of wetland biodiversity in Aotearoa New Zealand and highlight the value of eDNA databases for generating new insights from publicly shared data. They also emphasise an urgent need for greater resource allocation to conservation and restoration initiatives in Aotearoa New Zealand that will ensure the persistence of treasured native and endemic wetland species.

year: 2024-06-05

title: Long-term zooplankton dynamics in Lake Taupō: 2000-2020

authors: Miles, Galilee

subjects: Zooplankton

abstract: Long-term monitoring is essential for distinguishing between natural and anthropogenically induced changes within ecosystems, particularly those with high degrees of natural fluctuation. In order to gain further understanding of the links between physical, chemical and biotic factors, zooplankton have been highlighted as useful bioindicators within aquatic ecosystems. Long-term zooplankton monitoring studies have been utilized to highlight changes in lake trophic state, changes within catchments, fisheries practices and invasions.

Lake Taupō, New Zealand’s largest lake, has been subject to a long-term monitoring programme by NIWA since 1994, commissioned by the Waikato Regional Council, with the primary purpose of detecting changes in the lake’s trophic state through time. Since January 2000, the monitoring programme has included biweekly zooplankton sampling; no results of this have yet been published. The purpose of my research was to assess if there have been any significant changes in the zooplankton community composition over the monitoring period (2000-2020), with a particular focus on the last 12 years of data (2009-2020), and determine the importance of measured environmental variables in influencing changes in the zooplankton community composition.
Lake Taupō was assessed as microtrophic to oligotrophic throughout the monitoring period (Trophic Level Index (TLI) between 1.5 and 2.9), and there were no significant linear changes in any of the measured environmental variables (R-squared values all <0.07, p values all >0.05). The zooplankton data was separated into two separate datasets; a shorter February 2009 – December 2020 dataset with samples analysed entirely by myself, and a longer January 2000-December 2020 dataset, with earlier samples analysed by NIWA, utilising a lower taxonomic resolution.

Multivariate analyses (nMDS and ANOSIM) indicated significant differences among three yearly groups of zooplankton data within both the shorter (Global R statistic = 0.179, p = 0.014) and longer dataset (Global R statistic = 0.353, p = 0.001). Time and temperature were inferred by Redundancy Analysis (RDA) as the most important environmental variables associated with change in zooplankton community composition in both the shorter 2009-2020 (Lambda-A = 0.08 for both, p = 0.002 for both) and longer 2000-2020 datasets (Lambda-A = 0.15, p = 0.002 for time, and Lambda-A = 0.06, p = 0.002 for temperature). Both ordinations indicated that changes associated with time (long-term) and changes in temperature were primarily unrelated. Changes in zooplankton community composition influenced by temperature were attributed to seasonal succession.

Zooplankton community composition differed between the beginning and end of the monitoring periods in both datasets. However, the direction of the community change seemingly reversed around 2009-2011, with assemblages late in the study reverting to communities similar to those observed earlier in the study. Decreases in the native large Daphnia thomsoni and increased importance of the non-native Daphnia galeata indicate that colonisation by the invading species has influenced the observed changes in zooplankton community composition. The influences of top-down control in the form of predation on the zooplankton community by fish (an unmeasured variable) may have also influenced communities, with shifts from large- to small-sized species observed. Rotifers indicative of both low and high TLI are present throughout the study (e.g., Polyarthra dolichoptera and Keratella cochlearis respectively), but the community is dominated throughout by species indicative of low trophic state (e.g., Conochiloides dossuarius), which is consistent with previous zooplankton studies within Lake Taupō. Continued monitoring of zooplankton, physical and chemical lake properties, algae, and bacteria is advised, with the inclusion of fish monitoring recommended.

text: Long-term zooplankton dynamics in Lake Taupō: 2000-2020 Long-term monitoring is essential for distinguishing between natural and anthropogenically induced changes within ecosystems, particularly those with high degrees of natural fluctuation. In order to gain further understanding of the links between physical, chemical and biotic factors, zooplankton have been highlighted as useful bioindicators within aquatic ecosystems. Long-term zooplankton monitoring studies have been utilized to highlight changes in lake trophic state, changes within catchments, fisheries practices and invasions.

Lake Taupō, New Zealand’s largest lake, has been subject to a long-term monitoring programme by NIWA since 1994, commissioned by the Waikato Regional Council, with the primary purpose of detecting changes in the lake’s trophic state through time. Since January 2000, the monitoring programme has included biweekly zooplankton sampling; no results of this have yet been published. The purpose of my research was to assess if there have been any significant changes in the zooplankton community composition over the monitoring period (2000-2020), with a particular focus on the last 12 years of data (2009-2020), and determine the importance of measured environmental variables in influencing changes in the zooplankton community composition.
Lake Taupō was assessed as microtrophic to oligotrophic throughout the monitoring period (Trophic Level Index (TLI) between 1.5 and 2.9), and there were no significant linear changes in any of the measured environmental variables (R-squared values all <0.07, p values all >0.05). The zooplankton data was separated into two separate datasets; a shorter February 2009 – December 2020 dataset with samples analysed entirely by myself, and a longer January 2000-December 2020 dataset, with earlier samples analysed by NIWA, utilising a lower taxonomic resolution.

Multivariate analyses (nMDS and ANOSIM) indicated significant differences among three yearly groups of zooplankton data within both the shorter (Global R statistic = 0.179, p = 0.014) and longer dataset (Global R statistic = 0.353, p = 0.001). Time and temperature were inferred by Redundancy Analysis (RDA) as the most important environmental variables associated with change in zooplankton community composition in both the shorter 2009-2020 (Lambda-A = 0.08 for both, p = 0.002 for both) and longer 2000-2020 datasets (Lambda-A = 0.15, p = 0.002 for time, and Lambda-A = 0.06, p = 0.002 for temperature). Both ordinations indicated that changes associated with time (long-term) and changes in temperature were primarily unrelated. Changes in zooplankton community composition influenced by temperature were attributed to seasonal succession.

Zooplankton community composition differed between the beginning and end of the monitoring periods in both datasets. However, the direction of the community change seemingly reversed around 2009-2011, with assemblages late in the study reverting to communities similar to those observed earlier in the study. Decreases in the native large Daphnia thomsoni and increased importance of the non-native Daphnia galeata indicate that colonisation by the invading species has influenced the observed changes in zooplankton community composition. The influences of top-down control in the form of predation on the zooplankton community by fish (an unmeasured variable) may have also influenced communities, with shifts from large- to small-sized species observed. Rotifers indicative of both low and high TLI are present throughout the study (e.g., Polyarthra dolichoptera and Keratella cochlearis respectively), but the community is dominated throughout by species indicative of low trophic state (e.g., Conochiloides dossuarius), which is consistent with previous zooplankton studies within Lake Taupō. Continued monitoring of zooplankton, physical and chemical lake properties, algae, and bacteria is advised, with the inclusion of fish monitoring recommended.

year: 2021

title: Bizarre thoughts, magical ideations, and voices from the unconscious: Exploring issues of anomalous experience

authors: Tamatea, Armon J.

subjects: Maori

abstract: This project was initially concerned with the clinical interpretations of ‘bizarre’ or
‘magical’ ideations (i.e., statements considered to have little or no validity in our
predominant western culture). The first study explored clinical assessment issues
of who determines the validity of expressed beliefs and what kinds of criteria such
decisions are based on in the mental health field. The present study examined a
particular type of magical ideation, an auditory phenomenon involving claims that
forward spoken conversation contains hidden backwards speech embedded in the
vocal sounds. Thirty-two participants were invited to listen to various audio
samples of the alleged phenomenon and provide interpretations of what was heard.
Participants were assigned to four groups, each differing in the level of pre-emptive
information. A comparative measure revealed that priming and suggestion could
not be dismissed as alternative explanations of the reported effects. Clinical and
social implications will be discussed.

text: Bizarre thoughts, magical ideations, and voices from the unconscious: Exploring issues of anomalous experience This project was initially concerned with the clinical interpretations of ‘bizarre’ or
‘magical’ ideations (i.e., statements considered to have little or no validity in our
predominant western culture). The first study explored clinical assessment issues
of who determines the validity of expressed beliefs and what kinds of criteria such
decisions are based on in the mental health field. The present study examined a
particular type of magical ideation, an auditory phenomenon involving claims that
forward spoken conversation contains hidden backwards speech embedded in the
vocal sounds. Thirty-two participants were invited to listen to various audio
samples of the alleged phenomenon and provide interpretations of what was heard.
Participants were assigned to four groups, each differing in the level of pre-emptive
information. A comparative measure revealed that priming and suggestion could
not be dismissed as alternative explanations of the reported effects. Clinical and
social implications will be discussed.

year: 2003