title: The spatial dynamics of zooplankton communities in the Waikato River estuary, New Zealand

authors: Eludo, Charmaine Lyn Madriaga

abstract: Estuaries are transitional areas between streams or rivers and the ocean. Estuaries are affected by fluvial factors, such as freshwater and sediment inputs, and marine factors, including tidal influence, waves, and the inflow of salt water. The inherently dynamic nature of estuaries results in extreme changes in hydrographic characteristics, with the distribution of zooplankton being highly influenced. Zooplankton provide a crucial role in the biological communities of big rivers. However, they are extremely sensitive to environmental changes, particularly in estuarine environments. Consequently, this study aimed to examine how changes in physicochemical properties, such as salinity, affect species richness and zooplankton community composition along the Waikato River estuary, fed by New Zealand’s largest river. Eight sites were selected to represent the salinity gradient from the river mouth to a point where salinity was undetectable. Environmental variables, including temperature, dissolved oxygen, pH, salinity, and chlorophyll-a, as well as zooplankton communities, were examined at spring high tide (25 January 2023), spring low tide (8 March 2023) and neap high tide (15 March 2023). 

A canonical correspondence analysis (CCA) indicated that salinity explained the greatest proportion of variation in zooplankton community composition (26.8%, P=0.002). At the lower extreme of the gradient, zooplankton assemblages of the freshwater sites were dominated by freshwater rotifers such as Lecane luna, Synchaeta oblonga, Brachionus calyciflorus and Filinia novaezealandiae. The zooplankton assemblages of the saltwater sites were dominated by marine copepods, such as Oithona similis, Paracalanus parvus, Microsetella norvegica, and marine cladocerans such as Pleopis polyphemoides. Dissolved oxygen also significantly influenced zooplankton composition, independent of salinity (9.3%, P=0.004).  

At sites characterised by intermediate salinities in the Waikato River estuary, typical estuarine copepods (e.g., Gladioferens pectinatus) were absent. Sampling was conducted after high precipitation as well as a severe tropical cyclone which caused heavy rainfall and flooding. The strong influence of the tidal and riverine forces caused an unstable habitat for mid-salinity zooplankton communities to survive. It is predicted that with climate change, extreme weather events will likely become more frequent and severe in the future which pose a threat to less tolerant zooplankton species.

text: The spatial dynamics of zooplankton communities in the Waikato River estuary, New Zealand Estuaries are transitional areas between streams or rivers and the ocean. Estuaries are affected by fluvial factors, such as freshwater and sediment inputs, and marine factors, including tidal influence, waves, and the inflow of salt water. The inherently dynamic nature of estuaries results in extreme changes in hydrographic characteristics, with the distribution of zooplankton being highly influenced. Zooplankton provide a crucial role in the biological communities of big rivers. However, they are extremely sensitive to environmental changes, particularly in estuarine environments. Consequently, this study aimed to examine how changes in physicochemical properties, such as salinity, affect species richness and zooplankton community composition along the Waikato River estuary, fed by New Zealand’s largest river. Eight sites were selected to represent the salinity gradient from the river mouth to a point where salinity was undetectable. Environmental variables, including temperature, dissolved oxygen, pH, salinity, and chlorophyll-a, as well as zooplankton communities, were examined at spring high tide (25 January 2023), spring low tide (8 March 2023) and neap high tide (15 March 2023). 

A canonical correspondence analysis (CCA) indicated that salinity explained the greatest proportion of variation in zooplankton community composition (26.8%, P=0.002). At the lower extreme of the gradient, zooplankton assemblages of the freshwater sites were dominated by freshwater rotifers such as Lecane luna, Synchaeta oblonga, Brachionus calyciflorus and Filinia novaezealandiae. The zooplankton assemblages of the saltwater sites were dominated by marine copepods, such as Oithona similis, Paracalanus parvus, Microsetella norvegica, and marine cladocerans such as Pleopis polyphemoides. Dissolved oxygen also significantly influenced zooplankton composition, independent of salinity (9.3%, P=0.004).  

At sites characterised by intermediate salinities in the Waikato River estuary, typical estuarine copepods (e.g., Gladioferens pectinatus) were absent. Sampling was conducted after high precipitation as well as a severe tropical cyclone which caused heavy rainfall and flooding. The strong influence of the tidal and riverine forces caused an unstable habitat for mid-salinity zooplankton communities to survive. It is predicted that with climate change, extreme weather events will likely become more frequent and severe in the future which pose a threat to less tolerant zooplankton species.

year: 2023

title: Drivers and temporality of internal migration in the context of slow-onset natural hazards: Insights from north-west rural Bangladesh

authors: Kabir, Mohammad Ehsanul

subjects: Science & Technology

abstract: This paper examines the association between slow-onset natural hazards and the temporal aspects of human mobility— that is, short-term and long-term internal migration in the context of north-west Bangladesh. The paper contributes to the current understanding on the multiple stressors influencing individual's decisions to migrate from their rural origin, while examining the interplay between factors such as tipping points of migration (identified as drivers of migration), socio-demographic variables, and the contexts of slow-onset natural hazards. The analysis is based on empirical data relating to disadvantaged internal migrants or their household members living in drought-prone and riverine areas. A binary logistic regression model is used to analyse how various factors influence the temporality of migration. Key findings indicate that in the context of the natural hazards studied, financial stress at the household level and lack of economic resources are strongly associated with people's decisions to migrate for the-long or short-term. Based on such findings, the paper argues for diversified policy interventions for different groups of internal migrants in order to address difficulties associated with their mobility to and settlement at new locations.

text: Drivers and temporality of internal migration in the context of slow-onset natural hazards: Insights from north-west rural Bangladesh This paper examines the association between slow-onset natural hazards and the temporal aspects of human mobility— that is, short-term and long-term internal migration in the context of north-west Bangladesh. The paper contributes to the current understanding on the multiple stressors influencing individual's decisions to migrate from their rural origin, while examining the interplay between factors such as tipping points of migration (identified as drivers of migration), socio-demographic variables, and the contexts of slow-onset natural hazards. The analysis is based on empirical data relating to disadvantaged internal migrants or their household members living in drought-prone and riverine areas. A binary logistic regression model is used to analyse how various factors influence the temporality of migration. Key findings indicate that in the context of the natural hazards studied, financial stress at the household level and lack of economic resources are strongly associated with people's decisions to migrate for the-long or short-term. Based on such findings, the paper argues for diversified policy interventions for different groups of internal migrants in order to address difficulties associated with their mobility to and settlement at new locations.

year: 2018

title: Can the mana of Maori men who sexually abuse children be restored?

authors: Webb, Mate

subjects: Maori

abstract: The problem of child sex abuse is prevalent across all segments of society, and Maori, unfortunately, are overrepresented in this problem. In the total prison population of 6591, 13.6% are identified as child sex offenders. Of the 3,299 Maori in prison 283 (8.5%) are identified as child sex offenders whereas 631 (18.6%) of the 3292 non-Maori have been so identified. However, Maori only represent approximately 15% of the general population. In proportionate terms, approximately one of every 970 Maori men is currently in prison for child sex offences, while for non-Maori that figure is one in 31251. Also, disclosures from offenders suggest that sexual abuse is particularly common in rural or disadvantaged areas, with offenders frequently reporting being abused by multiple offenders and being aware of chronic abuse, little of which was ever reported.

text: Can the mana of Maori men who sexually abuse children be restored? The problem of child sex abuse is prevalent across all segments of society, and Maori, unfortunately, are overrepresented in this problem. In the total prison population of 6591, 13.6% are identified as child sex offenders. Of the 3,299 Maori in prison 283 (8.5%) are identified as child sex offenders whereas 631 (18.6%) of the 3292 non-Maori have been so identified. However, Maori only represent approximately 15% of the general population. In proportionate terms, approximately one of every 970 Maori men is currently in prison for child sex offences, while for non-Maori that figure is one in 31251. Also, disclosures from offenders suggest that sexual abuse is particularly common in rural or disadvantaged areas, with offenders frequently reporting being abused by multiple offenders and being aware of chronic abuse, little of which was ever reported.

year: 2008