title: Distinct migratory and non-migratory ecotypes of an endemic New Zealand eleotrid (Gobiomorphus cotidianus) – implications for incipient speciation in island freshwater fish species

authors: Michel, Christian

abstract: Background: Many postglacial lakes contain fish species with distinct ecomorphs. Similar evolutionary scenarios might be acting on evolutionarily young fish communities in lakes of remote islands. One process that drives diversification in island freshwater fish species is the colonization of depauperate freshwater environments by diadromous (migratory) taxa, which secondarily lose their migratory behaviour. The loss of migration limits dispersal and gene flow between distant populations, and, therefore, is expected to facilitate local morphological and genetic differentiation. To date, most studies have focused on interspecific relationships among migratory species and their non-migratory sister taxa. We hypothesize that the loss of migration facilitates intraspecific morphological, behavioural, and genetic differentiation between migratory and non-migratory populations of facultatively diadromous taxa, and, hence, incipient speciation of island freshwater fish species. Results: Microchemical analyses of otolith isotopes (88Sr, 137Ba and 43Ca) differentiated migratory and non-migratory stocks of the New Zealand endemic Gobiomorphus cotidianus McDowall (Eleotridae). Samples were taken from two rivers, one lake and two geographically-separated outgroup locations. Meristic analyses of oculoscapular lateral line canals documented a gradual reduction of these structures in the non-migratory populations. Amplified fragment length polymorphism (AFLP) fingerprints revealed considerable genetic isolation between migratory and non-migratory populations. Temporal differences in reproductive timing (migratory = winter spawners, non-migratory = summer spawners; as inferred from gonadosomatic indices) provide a prezygotic reproductive isolation mechanism between the two ecotypes. Conclusion:This study provides a holistic look at the role of diadromy in incipient speciation of island freshwater fish species. All four analytical approaches (otolith microchemistry, morphology, spawning timing, population genetics) yield congruent results, and provide clear and independent evidence for the existence of distinct migratory and non-migratory ecotypes within a river in a geographically confined range. The morphological changes within the non-migratory populations parallel interspecific patterns observed in all non-migratory New Zealand endemic Gobiomorphus species and other derived gobiid taxa, a pattern suggesting parallel evolution. This study indicates, for the first time, that distinct ecotypes of island freshwater fish species may be formed as a consequence of loss of migration and subsequent diversification. Therefore, if reproductive isolation persists, these processes may provide a mechanism to facilitate speciation.

text: Distinct migratory and non-migratory ecotypes of an endemic New Zealand eleotrid (Gobiomorphus cotidianus) – implications for incipient speciation in island freshwater fish species Background: Many postglacial lakes contain fish species with distinct ecomorphs. Similar evolutionary scenarios might be acting on evolutionarily young fish communities in lakes of remote islands. One process that drives diversification in island freshwater fish species is the colonization of depauperate freshwater environments by diadromous (migratory) taxa, which secondarily lose their migratory behaviour. The loss of migration limits dispersal and gene flow between distant populations, and, therefore, is expected to facilitate local morphological and genetic differentiation. To date, most studies have focused on interspecific relationships among migratory species and their non-migratory sister taxa. We hypothesize that the loss of migration facilitates intraspecific morphological, behavioural, and genetic differentiation between migratory and non-migratory populations of facultatively diadromous taxa, and, hence, incipient speciation of island freshwater fish species. Results: Microchemical analyses of otolith isotopes (88Sr, 137Ba and 43Ca) differentiated migratory and non-migratory stocks of the New Zealand endemic Gobiomorphus cotidianus McDowall (Eleotridae). Samples were taken from two rivers, one lake and two geographically-separated outgroup locations. Meristic analyses of oculoscapular lateral line canals documented a gradual reduction of these structures in the non-migratory populations. Amplified fragment length polymorphism (AFLP) fingerprints revealed considerable genetic isolation between migratory and non-migratory populations. Temporal differences in reproductive timing (migratory = winter spawners, non-migratory = summer spawners; as inferred from gonadosomatic indices) provide a prezygotic reproductive isolation mechanism between the two ecotypes. Conclusion:This study provides a holistic look at the role of diadromy in incipient speciation of island freshwater fish species. All four analytical approaches (otolith microchemistry, morphology, spawning timing, population genetics) yield congruent results, and provide clear and independent evidence for the existence of distinct migratory and non-migratory ecotypes within a river in a geographically confined range. The morphological changes within the non-migratory populations parallel interspecific patterns observed in all non-migratory New Zealand endemic Gobiomorphus species and other derived gobiid taxa, a pattern suggesting parallel evolution. This study indicates, for the first time, that distinct ecotypes of island freshwater fish species may be formed as a consequence of loss of migration and subsequent diversification. Therefore, if reproductive isolation persists, these processes may provide a mechanism to facilitate speciation.

year: 2008-02

title: Evaluating biochar and fungi for the remediation of PFAS in landfill leachates.

authors: Chauhan, Rushirajsinh

abstract: Per- and polyfluoroalkyl substances (PFAS) have become widespread environmental 
contaminants, often detected in various ecosystems, including waterways, and found in 
numerous products such as cosmetics. In New Zealand, PFAS contamination poses a 
significant risk to both environmental and human health. This study works towards developing 
an innovative PFAS removal technology utilizing biochar to adsorb PFAS and fungi to degrade 
PFAS. The work was broken into several stages, the first finding suitable growing conditions 
for fungi on biochar and attempting to quantify the growth, the second examining biochar 
adsorption properties, first with humic acid and the second with PFAS. Three different types 
of fungi, Oyster, Shiitake, and Pekepeke (native to New Zealand), were cultivated on biochar 
and substrates made from woodchips and other organic materials. Growth was best on a 
combination of biochar and woodchip. The chloroform fumigation method showed that the 
oyster/biochar culture had a growth of 17.6 mg/g/day, while shitake/biochar was 14.6 mg/g/day 
and the oyster/biochar/woodchip had a growth of 20.7 mg/g/day.
Biochar had a low adsorption capacity (5 mg/g) and affinity for humic acid. The Freundlich 
isotherm gave a marginally better fit to adsorption data than the Langmuir and SIPS isotherms. 
The low adsorption was due to both humic acid and biochar having predominantly negative 
charges, biochar had a surface charge of 0.824 mM -ve charges/g biochar, six times that of dry 
soil which has a surface charge of 0.125 mM/g soil. Biochar was tested for its ability to adsorb 
three species of PFAS (PFBSA, PFHexA, PHHepA). Under the environmentally relevant 
PFAS concentration ranges tested, biochar adsorbed all of the PFAS, resulting in no PFAS 
being able to be detected in solution. PFAS adsorption to the biochar is predominantly by 
hydrogen bonding

text: Evaluating biochar and fungi for the remediation of PFAS in landfill leachates. Per- and polyfluoroalkyl substances (PFAS) have become widespread environmental 
contaminants, often detected in various ecosystems, including waterways, and found in 
numerous products such as cosmetics. In New Zealand, PFAS contamination poses a 
significant risk to both environmental and human health. This study works towards developing 
an innovative PFAS removal technology utilizing biochar to adsorb PFAS and fungi to degrade 
PFAS. The work was broken into several stages, the first finding suitable growing conditions 
for fungi on biochar and attempting to quantify the growth, the second examining biochar 
adsorption properties, first with humic acid and the second with PFAS. Three different types 
of fungi, Oyster, Shiitake, and Pekepeke (native to New Zealand), were cultivated on biochar 
and substrates made from woodchips and other organic materials. Growth was best on a 
combination of biochar and woodchip. The chloroform fumigation method showed that the 
oyster/biochar culture had a growth of 17.6 mg/g/day, while shitake/biochar was 14.6 mg/g/day 
and the oyster/biochar/woodchip had a growth of 20.7 mg/g/day.
Biochar had a low adsorption capacity (5 mg/g) and affinity for humic acid. The Freundlich 
isotherm gave a marginally better fit to adsorption data than the Langmuir and SIPS isotherms. 
The low adsorption was due to both humic acid and biochar having predominantly negative 
charges, biochar had a surface charge of 0.824 mM -ve charges/g biochar, six times that of dry 
soil which has a surface charge of 0.125 mM/g soil. Biochar was tested for its ability to adsorb 
three species of PFAS (PFBSA, PFHexA, PHHepA). Under the environmentally relevant 
PFAS concentration ranges tested, biochar adsorbed all of the PFAS, resulting in no PFAS 
being able to be detected in solution. PFAS adsorption to the biochar is predominantly by 
hydrogen bonding

year: 2024-10-20

title: Understanding student learning in environmental education in Aotearoa New Zealand

authors: Eames, Chris W.

subjects: environmental education

abstract: This paper seeks to provide a perspective on environmental education in Aotearoa New Zealand. To contextualise this perspective, it illustrates how environmental, socio-cultural and political imperatives have shaped the development of environmental education in this land. These imperatives illuminate the natural history of the country, the connectedness within the worldviews of the indigenous Maori people, the pioneering views of some enlightened European settlers, and tensions between development and conservation. We connect this context with an overview of research in Aotearoa New Zealand into one aspect of environmental education - student learning in schools. Examples from recent research in this area are provided to show how these approaches are contributing to the Aotearoa New Zealand-ness of environmental education.

text: Understanding student learning in environmental education in Aotearoa New Zealand This paper seeks to provide a perspective on environmental education in Aotearoa New Zealand. To contextualise this perspective, it illustrates how environmental, socio-cultural and political imperatives have shaped the development of environmental education in this land. These imperatives illuminate the natural history of the country, the connectedness within the worldviews of the indigenous Maori people, the pioneering views of some enlightened European settlers, and tensions between development and conservation. We connect this context with an overview of research in Aotearoa New Zealand into one aspect of environmental education - student learning in schools. Examples from recent research in this area are provided to show how these approaches are contributing to the Aotearoa New Zealand-ness of environmental education.

year: 2011