title: Reproductive biology of yellowbelly flounder Rhombosolea leporina (Günther, 1862) and Rhombosolea spp.

authors: Koverman, Ryan

abstract: Yellowbelly flounder Rhombosolea leporina is a culturally, recreationally, and commercially important flounder species in New Zealand. R. leporina contain high-quality flesh and sexually dimorphic growth, where females grow more rapid and reach an overall larger size than males. These biological characteristics make R. leporina an enticing opportunity for aquaculture. Aquaculture is becoming an increasingly important capability in global food security and an alternative to wild capture fisheries. Understanding and controlling the reproductive biology of an aquaculture species candidate is required to ensure successful production. The understanding of the reproductive biology also facilitates the effective management of wild stocks. Currently, there is a limited amount of literature on the reproductive cycle of R. leporina and no previous literature available on the sexual differentiation in Rhombosolea spp. This study provides a histological investigation into the reproductive cycle of adult female R. leporina, from November 2015 – October 2017, and sexual differentiation in Rhombosolea spp. juveniles. It was found that R. leporina spawns over a protracted seven-month season, from June to December. Based on the histological observations it was apparent that R. leporina have multiple group synchronous ovarian development with the potential of batch spawning. The investigation into sexual differentiation in the Rhombosolea spp. juveniles revealed gonadal cavities in all individuals, making ovarian cavities an inadequate criterion of sex. Therefore, it was found that the juveniles display sexual differentiation at 47 mm TL and 57 mm TL, for females with meiotic oocytes and males with spermatocytes respectively. Furthermore, spermatozoa were present in testes of a 71 mm TL male. These results provide insights into the precise timing of reproductive development and the size at sexual differentiation. The results presented here may facilitate further investigations into the endocrine regulation or manipulation of the reproductive biology of R. leporina. The implication of the investigation into Rhombosolea spp. juveniles illustrate the necessity of more robust investigations into the timing of sexual differentiation and initial gonadal development alongside insights into gene expression. Nonetheless, these findings provide essential background knowledge on the reproductive biology of R. leporina and Rhombosolea spp. juveniles for the potential of aquaculture and management of wild stocks.

text: Reproductive biology of yellowbelly flounder Rhombosolea leporina (Günther, 1862) and Rhombosolea spp. Yellowbelly flounder Rhombosolea leporina is a culturally, recreationally, and commercially important flounder species in New Zealand. R. leporina contain high-quality flesh and sexually dimorphic growth, where females grow more rapid and reach an overall larger size than males. These biological characteristics make R. leporina an enticing opportunity for aquaculture. Aquaculture is becoming an increasingly important capability in global food security and an alternative to wild capture fisheries. Understanding and controlling the reproductive biology of an aquaculture species candidate is required to ensure successful production. The understanding of the reproductive biology also facilitates the effective management of wild stocks. Currently, there is a limited amount of literature on the reproductive cycle of R. leporina and no previous literature available on the sexual differentiation in Rhombosolea spp. This study provides a histological investigation into the reproductive cycle of adult female R. leporina, from November 2015 – October 2017, and sexual differentiation in Rhombosolea spp. juveniles. It was found that R. leporina spawns over a protracted seven-month season, from June to December. Based on the histological observations it was apparent that R. leporina have multiple group synchronous ovarian development with the potential of batch spawning. The investigation into sexual differentiation in the Rhombosolea spp. juveniles revealed gonadal cavities in all individuals, making ovarian cavities an inadequate criterion of sex. Therefore, it was found that the juveniles display sexual differentiation at 47 mm TL and 57 mm TL, for females with meiotic oocytes and males with spermatocytes respectively. Furthermore, spermatozoa were present in testes of a 71 mm TL male. These results provide insights into the precise timing of reproductive development and the size at sexual differentiation. The results presented here may facilitate further investigations into the endocrine regulation or manipulation of the reproductive biology of R. leporina. The implication of the investigation into Rhombosolea spp. juveniles illustrate the necessity of more robust investigations into the timing of sexual differentiation and initial gonadal development alongside insights into gene expression. Nonetheless, these findings provide essential background knowledge on the reproductive biology of R. leporina and Rhombosolea spp. juveniles for the potential of aquaculture and management of wild stocks.

year: 2018

title: Could ‘Isochoric Freezing’ revolutionise food preservation?

authors: Fikiin, K

subjects: chilling

abstract: The present article responds to the food engineering community’s growing interest in an emerging and lauded approach to food preservation, popularised by its developers as ‘isochoric freezing’. A strong campaign in the scientific literature and mass media has recently promoted this technique as a universal replacement for traditional food freezing and the frozen supply chain by highlighting a number of alleged advantages of ‘isochoric freezing’. Some of these claims therefore require a more neutral and critical assessment against the background of the today’s state of the art in food freezing technologies. Hence, this article spotlights several concerns regarding the plausibility, energy expenditure, resource efficiency, process rate, throughput and safety of ‘isochoric freezing’, as well as the correct use of food refrigeration terminology. The aspects considered are intended to make food scientists, technologists and engineers more aware of the real capabilities and the application perspectives of this still immature mode of refrigerated food processing.

text: Could ‘Isochoric Freezing’ revolutionise food preservation? The present article responds to the food engineering community’s growing interest in an emerging and lauded approach to food preservation, popularised by its developers as ‘isochoric freezing’. A strong campaign in the scientific literature and mass media has recently promoted this technique as a universal replacement for traditional food freezing and the frozen supply chain by highlighting a number of alleged advantages of ‘isochoric freezing’. Some of these claims therefore require a more neutral and critical assessment against the background of the today’s state of the art in food freezing technologies. Hence, this article spotlights several concerns regarding the plausibility, energy expenditure, resource efficiency, process rate, throughput and safety of ‘isochoric freezing’, as well as the correct use of food refrigeration terminology. The aspects considered are intended to make food scientists, technologists and engineers more aware of the real capabilities and the application perspectives of this still immature mode of refrigerated food processing.

year: 2024

title: The source, composition and typology of ‘Limestone’ Adzes from Eastern North Island, New Zealand

authors: Nelson, Campbell S.

subjects: adzes

abstract: Collections of stone adzes (toki) from the eastern North Island of New Zealand include a number of typologically early (Archaic) forms made from what has been previously described as ‘siliceous or silicified limestone’. Seventy five finished adzes and preforms of this material were recorded in the present study. Their geographic distribution is primarily restricted to southern Hawkes Bay – Wairarapa, and they apparently originated from a single manufacturing centre at Owahanga, on the northern Wairarapa coast. Chemical and mineralogical analyses (by X-ray fluorescence, portable XRF, vacuum gasometry and X-ray diffraction) of two artefacts from Owahanga show they contain about 20–30 per cent CaCO3 (as calcite), while samples of the presumed local source rock have a slightly higher carbonate content but comparable silica (quartz) and Rb concentrations. The rock type used in the manufacture of adzes was therefore not a true limestone but calcareous mudstone, compositionally distinct from siliceous limestones in southern Wairarapa and probably derived from the Whangai Formation. Possible reasons for the use of this stone material are discussed.

text: The source, composition and typology of ‘Limestone’ Adzes from Eastern North Island, New Zealand Collections of stone adzes (toki) from the eastern North Island of New Zealand include a number of typologically early (Archaic) forms made from what has been previously described as ‘siliceous or silicified limestone’. Seventy five finished adzes and preforms of this material were recorded in the present study. Their geographic distribution is primarily restricted to southern Hawkes Bay – Wairarapa, and they apparently originated from a single manufacturing centre at Owahanga, on the northern Wairarapa coast. Chemical and mineralogical analyses (by X-ray fluorescence, portable XRF, vacuum gasometry and X-ray diffraction) of two artefacts from Owahanga show they contain about 20–30 per cent CaCO3 (as calcite), while samples of the presumed local source rock have a slightly higher carbonate content but comparable silica (quartz) and Rb concentrations. The rock type used in the manufacture of adzes was therefore not a true limestone but calcareous mudstone, compositionally distinct from siliceous limestones in southern Wairarapa and probably derived from the Whangai Formation. Possible reasons for the use of this stone material are discussed.

year: 2016