title: Protogynous sex change in sexually immature spotty wrasse (Notolabrus celidotus)

authors: Hamer, Tessa Ellen

subjects: Aquaculture

abstract: One of the most unique forms of sexual plasticity can be witnessed in sequentially hermaphroditic fish, which begin as one sex and change to another at some stage in their lifecycle. The endemic protogynous spotty wrasse (Notolabrus Celidotus), has historically been considered monandric although two male morphs appear to exist. To date the majority of research has focused on sexually mature females that are changing sex to become terminal phase males. The current study seeks to describe sex change in sexually immature females that are transitioning to become initial phase males. This was achieved through analysis of gonadal histology as well as expression of three key sex differentiation related genes (amh, dmrt1 and cyp19a1a). Fish (n=141) were caught from the Tauranga Harbour ranging in size from 52-270 mm TL from May-June 2022. The smallest transitional fish identified was 52 mm TL and the smallest IP male detected in this study were 72 mm TL, indicating IP male spotty wrasse likely reach sexual maturity at a much earlier and smaller developmental stage than previously realised. Expression of amh and dmrt1 showed a clear male-bias across sex change, with the former being upregulated in early sex change. The aromatase gene, cyp19a1a showed an overall female-biased expression pattern despite having some unexpected upregulation in the mid stages of sex change. The results supported previous reports that all juvenile spotty wrasse are female first before some individuals undergo pre-maturational sex change to become IP males. Having clarified the process of sex change leading to IP male formation and considering data from other studies of IP and TP testicular structure in this species, it seems no longer tenable to consider them monandric.

text: Protogynous sex change in sexually immature spotty wrasse (Notolabrus celidotus) One of the most unique forms of sexual plasticity can be witnessed in sequentially hermaphroditic fish, which begin as one sex and change to another at some stage in their lifecycle. The endemic protogynous spotty wrasse (Notolabrus Celidotus), has historically been considered monandric although two male morphs appear to exist. To date the majority of research has focused on sexually mature females that are changing sex to become terminal phase males. The current study seeks to describe sex change in sexually immature females that are transitioning to become initial phase males. This was achieved through analysis of gonadal histology as well as expression of three key sex differentiation related genes (amh, dmrt1 and cyp19a1a). Fish (n=141) were caught from the Tauranga Harbour ranging in size from 52-270 mm TL from May-June 2022. The smallest transitional fish identified was 52 mm TL and the smallest IP male detected in this study were 72 mm TL, indicating IP male spotty wrasse likely reach sexual maturity at a much earlier and smaller developmental stage than previously realised. Expression of amh and dmrt1 showed a clear male-bias across sex change, with the former being upregulated in early sex change. The aromatase gene, cyp19a1a showed an overall female-biased expression pattern despite having some unexpected upregulation in the mid stages of sex change. The results supported previous reports that all juvenile spotty wrasse are female first before some individuals undergo pre-maturational sex change to become IP males. Having clarified the process of sex change leading to IP male formation and considering data from other studies of IP and TP testicular structure in this species, it seems no longer tenable to consider them monandric.

year: 2023

title: Geology of the western Mamaku Plateau and variations in the Mamaku ignimbrite

authors: Fransen, Pieter J.B.

subjects: Geology

abstract: Pleistocene ignimbrites in the western Mamaku Plateau east of Putaruru consist of the following successively younger formations: (?) Ongatiti Ignimbrite, Ahuroa Ignimbrite, Whakamaru Ignimbrite, Waihou Ignimbrite (new), Waimakariri Ignimbrite (new), Mamaku Ignimbrite. They can be distinguished on the basis of their compositional-, welding-, textural-, and field characteristics. The ignimbrites are separated by unconformities, and intercalated fluvial sedimentary deposits. The three most important units are the Whakamaru, Waimakariri and Mamaku Ignimbrites, which are well exposed and widespread.

The Mamaku Ignimbrite covers a surface area of nearly 4300 km² on the Mamaku Plateau. Corresponding vertical changes in lithology, petrography and physical properties near the Rotorua Caldera define two flow members: a lower Sheet 1, and an upper Sheet 2, each of which is about 60 m thick. The ignimbrite constitutes a simple cooling unit which indicates that Sheet 2 was emplaced shortly after Sheet 1. Only one sheet (? Sheet 1) is evident in the western Mamaku Plateau. Welding zonation near-to-source is characterised by a gradual change from a basal glassy lenticulite zone to a nonwelded top. Smith's (1960b) zonal classification ranks the ignimbrite as being partially welded. This condition suggests that total thickness is not necessarily a major factor in the degree of welding of ignimbrites. 

The phenocryst assemblage of plagioclase, quartz, pyroxene, opaques, hornblende and biotite, is set in a devitrified fine ash matrix, which is an ubiquitous feature of the ignimbrite. Higher modal phenocryst content at the base of each sheet is attributed to compaction. Overall the phenocrysts are uniformly distributed and there is little vertical variation. Seven bulk chemical analyses reveal only minor vertical variations in composition. The near uniform chemical and mineralogical trends suggest nondifferentiation of the source magma. 

Texturally the Mamaku Ignimbrite is a poorly sorted lapilli ash. The grading of fragments like that shown in "the standard ignimbrite flow unit" is absent. However, the presence of a zone of aligned pumice fragments indicates that laminar flow operated during the later stages of deposition. Two major inferred faults in the western Mamaku Plateau define a western horst, a central graben, and an eastern horst. The eastern horst is postulated to be the southern extension of the axial median horst in the Hauraki Depression and of the Hauraki Rift. 

Repeated and extended intervals of erosion followed the emplacement of the ignimbrites. Detritus from the eroding sheets was removed by rivers flowing into the Hauraki Depression. Construction of the Mamaku Plateau has largely taken place since the eruption of the Whakamaru Ignimbrite, c.300,000 years ago, and terminated with the eruption of the Mamaku Ignimbrite, c.l40,000 years ago. Excavation of the long deep valleys in the plateau occurred mainly in the latter 42,000 years.

text: Geology of the western Mamaku Plateau and variations in the Mamaku ignimbrite Pleistocene ignimbrites in the western Mamaku Plateau east of Putaruru consist of the following successively younger formations: (?) Ongatiti Ignimbrite, Ahuroa Ignimbrite, Whakamaru Ignimbrite, Waihou Ignimbrite (new), Waimakariri Ignimbrite (new), Mamaku Ignimbrite. They can be distinguished on the basis of their compositional-, welding-, textural-, and field characteristics. The ignimbrites are separated by unconformities, and intercalated fluvial sedimentary deposits. The three most important units are the Whakamaru, Waimakariri and Mamaku Ignimbrites, which are well exposed and widespread.

The Mamaku Ignimbrite covers a surface area of nearly 4300 km² on the Mamaku Plateau. Corresponding vertical changes in lithology, petrography and physical properties near the Rotorua Caldera define two flow members: a lower Sheet 1, and an upper Sheet 2, each of which is about 60 m thick. The ignimbrite constitutes a simple cooling unit which indicates that Sheet 2 was emplaced shortly after Sheet 1. Only one sheet (? Sheet 1) is evident in the western Mamaku Plateau. Welding zonation near-to-source is characterised by a gradual change from a basal glassy lenticulite zone to a nonwelded top. Smith's (1960b) zonal classification ranks the ignimbrite as being partially welded. This condition suggests that total thickness is not necessarily a major factor in the degree of welding of ignimbrites. 

The phenocryst assemblage of plagioclase, quartz, pyroxene, opaques, hornblende and biotite, is set in a devitrified fine ash matrix, which is an ubiquitous feature of the ignimbrite. Higher modal phenocryst content at the base of each sheet is attributed to compaction. Overall the phenocrysts are uniformly distributed and there is little vertical variation. Seven bulk chemical analyses reveal only minor vertical variations in composition. The near uniform chemical and mineralogical trends suggest nondifferentiation of the source magma. 

Texturally the Mamaku Ignimbrite is a poorly sorted lapilli ash. The grading of fragments like that shown in "the standard ignimbrite flow unit" is absent. However, the presence of a zone of aligned pumice fragments indicates that laminar flow operated during the later stages of deposition. Two major inferred faults in the western Mamaku Plateau define a western horst, a central graben, and an eastern horst. The eastern horst is postulated to be the southern extension of the axial median horst in the Hauraki Depression and of the Hauraki Rift. 

Repeated and extended intervals of erosion followed the emplacement of the ignimbrites. Detritus from the eroding sheets was removed by rivers flowing into the Hauraki Depression. Construction of the Mamaku Plateau has largely taken place since the eruption of the Whakamaru Ignimbrite, c.300,000 years ago, and terminated with the eruption of the Mamaku Ignimbrite, c.l40,000 years ago. Excavation of the long deep valleys in the plateau occurred mainly in the latter 42,000 years.

year: 1982

title: How Maui captured the sun: using a MUD for educational simulation

authors: Cunningham, Sally Jo

subjects: computer science

abstract: MUDs (Multi-User Dungeons) are text-based, multi-user communication and modelling programs. This paper investigates the potential of a popular extensible MUD, the LambdaMOO system, as a tool for second language training and for educational simulation gaming.

text: How Maui captured the sun: using a MUD for educational simulation MUDs (Multi-User Dungeons) are text-based, multi-user communication and modelling programs. This paper investigates the potential of a popular extensible MUD, the LambdaMOO system, as a tool for second language training and for educational simulation gaming.

year: 1995-12