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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Challenges that offenders face upon release that contribute to recidivism in the Department of Correctional Services: A case study of the West Coast Medium ' A' Correctional Centre in the Western Cape

Samuels, Jerome Alex January 2010 (has links)
<p>The research comprises an exploratory study of the challenges that offenders face upon release and which contribute to recidivism in the Department of Correctional Services (DCS). The West Coast Medium &lsquo / A&rsquo / Correctional Centre in the Western Cape has been selected as the case study area. Although offenders attend various rehabilitation programmes inside the prison, it has become apparent that upon their release this rehabilitation is not sustained. The qualitative methodology used for this research included semi-structured interviews in order to gather information on the challenges that contribute to recidivism. Offenders, parolees, family members, the Head of Social Reintegration, a social worker, a representative of NICRO, the Chairperson of the Atlantis Community Police Forum, and a spokesperson for SAPS Atlantis were interviewed in order to gather the relevant information. The general findings of the research demonstrate that the adverse socio-economic conditions confronting the offenders after their release from prison are the main barriers to their successful rehabilitation and reintegration into society. The problem is further compounded by the high incidence of criminal activities within the community environment, the influence of gangsterism, peer pressure and substance abuse. Together, these conditions lead to the re-committing of crime, the re-incarceration of former offenders and, ultimately, to a pattern of recidivism.</p>
22

Site characterisation of the Whataroa Valley for the Deep Alpine Fault Drilling Project stage 2 (DFDP-2), West Coast, New Zealand

Klahn, Andrew Paul January 2011 (has links)
The Alpine Fault in western South Island ruptures every 300±100 years in large magnitude (7.8 ± 3) earthquakes and presents a major seismic hazard to New Zealand. The Deep Alpine Fault Drilling Project (DFDP) aims to drill, sample, and monitor the Alpine Fault in order to investigate the processes of earthquake genesis, rock deformation, and fault gouge formation for a tectonically active fault late in the seismic cycle. Rapid dextral reverse movements and exhumation rates on the central section of the Alpine Fault at Whataroa Valley make this a geologically favourable setting to drill and sample fault rocks at depth that can be correlated with surface exposures. The suitability of a site for stationing a major drilling operation depends upon practical issues such as the engineering geological characteristics of the proposed site, possible geohazards, and drilling logistics. This thesis presents new engineering geological, geophysical, and geomorphic investigations of the Whataroa Valley for the DFDP-2 drill site in order to provide a framework for proposed future operations. MASW, GPR and basic geotechnical methods such as test pits and face logs were conducted at various locations at the site to gain geotechnical properties and attempt to find depth to bedrock. Results showed bedrock is at least 25m deep as it was not seen in any of the GPR surveys. Correlation of the MASW and GPR profiles with freshly eroded and face logged outcrops permitted assignment of s-wave velocities to each of the gravels present and confirmation of features seen in the geophysical surveys. Vs30 values gained from the MASW classed the gravels as a soft soil in Site Class D in NZS 1170.5. Expected peak ground accelerations at the study site during an Alpine Fault earthquake are estimated at ≥0.8g. The Whataroa River is actively eroding the southern edge of the investigation area. Comparison of historic aerial photos and newly obtained LiDAR showed the river bank has moved a total of 165 m since 1948, a majority of that occurring in the past decade, 35 m of erosion occurring over a few days during early January 2011. Little correlation between heavy rainfall periods and increased erosion rates suggest changing channel dynamics play a major part in the channel migration. Modelling of the threshold discharges required to overtop the Whataroa terraces results in return periods several orders of magnitude larger than Alpine Fault earthquake recurrence intervals that result in major sediment pulses, implying that inundation from river flooding under current channel conditions is highly unlikely. Debris flows originating from the west valley wall have been identified as a possible hazard to drilling operations. Recent debris flows were easily mapped due to the changes in vegetation, whereas the remnants of historic debris flows were able to be mapped using the LiDAR. Studies of these show that they have a minimal run out distance (<100 m), and can be easily avoided by ensuring the drill site is located outside the proposed debris flow risk zone plus a 50 m buffer that has been added for caution. Current uncertainty of the fault dip and target depth of the hole causes large variation in proposed drill rig locations at the surface. All of the investigations are summarised on a hazard map used to suggest a range of favoured drill sites based on varied angle dips and drilling depths, minimizing flood, erosion and sediment inundation hazards, and specifying access routes.
23

A study on the Construction and Ecological succession of two Small Artificial Reefs on the Swedish West Coast

Forsberg, Malin, Järlind, Joakim January 2014 (has links)
Artificial reefs are being built in most parts of the world for a wide variety of purposes. Divingtourism is a common motivator for the construction of many reefs, particularly in the tropics,although the most widely used purpose is to improve or reconstruct hard bottom habitats andincrease the yield from fisheries. There are two main reasons for why aquatic life is attracted toartificial reefs. They provide excellent protection by often being hollow or filled with crevicesand cavities and increasing opportunities for improved foraging through accumulating biomassand extending the foraging range of an organism by acting like stepping stones. Sweden is acoastal country with few artificial reefs. In this study, two reefs were constructed in the sea offthe coast of Halmstad, Sweden to test small scale artificial reef production, marine organismcolonisation of the reefs during the first year, and to increase the local marine life diversity.Many marine organisms that would not normally occur in the sites where the reefs wereconstructed were observed, such as Symphodus melops and Anguilla anguilla. The reefs alsoprovided a new “clean slate” substrate for the settling of sessile organisms such as Urticina felinaor partially sessile organisms (i.e. during a certain stage of their life-cycle) such as some speciesof Cnidaria polyps. The tested method to construct these reefs was relatively cost effective for itspurpose. However a few minor but vital improvements, such as better binding materials, areneeded. Local marine life in the area has become more diverse during the experiment and thatalone is enough reason to motivate construction of similar reefs along the Swedish coast. / Artificiella rev anläggs runt om i världen med en mängd olika syften. Det är vanligt att dykturism används som anledning för att bygga artificiella rev, speciellt i tropikerna. Restaurering av hårdbottenrev och mål att öka kommersiella fiskebestånd är dock de största motiveringarna. Det finns två huvudsakliga orsaker till varför akvatiskt liv attraheras av konstgjorda rev. De erbjuder utmärkt skydd i form av håligheter och sprickor, samt att de ökar möjligheterna för födosök genom att ackumulera biomassa och fungera som ”stepping stones”, det vill säga utöka födosökningsområdet. Sverige är ett kustland med få artificiella rev. Två rev anlades i Laholmsbukten, Kattegatt, just utanför Tjuvahålan i Halmstad med syftet att undersöka effektiviteten och nyttan av småskaliga rev, att studera marina organismers kolonisering av reven och att öka den lokala biodiversiteten. Många marina organismer som inte borde förkommit i området där reven anlagts tidigare observerades. Ett par exempel är Symphodus melops) och (Anguilla anguilla). Reven fungerade även som rena underlag för sessila organismer att fästa på. Djur som till exempel havsros (Urticina felina) och Cnidariapolyper noterades. Metoden för att konstruera reven visade sig vara kostnadseffektiv i förhållande till syftet, men några viktiga steg, bland annat fästmaterialet, behöver förbättras. Den lokala artmångfalden ökade efter anläggningen av reven och borde vara nog motivering för att fortsätta bygga liknande rev längs den svenska kusten.
24

Contesting natures : a discourse analysis of natural resource conflicts

Walton, Sara, n/a January 2008 (has links)
This research explores the discursive formations involved in two environmental conflicts during which organisations were not permitted to carry out their proposed extractive activities. The conflicts were based on the West Coast of the South Island in New Zealand. The first involved sustainable native logging and the second was over the siting and extension of a gold mine. Extensive archival and media searches were carried out to generate data on the conflicts. Interviews were also conducted to investigate the community position in more depth. The discourse theory of Laclau and Mouffe (2001 [1985]) is drawn upon as a framework to make sense of the conflicts. This framework was particularly useful as it enabled a close and careful examination of the antagonisms and addressed some of the ideological and power concerns with stakeholder analysis. The analysis involved identifying nodal points, subjectivity, subject positions and floating signifiers, which enabled certain hegemonic constructions. The two conflicts were considerably different. The hegemonic constructions were quite similar and the notion of �being green� emerged as an antagonism that was at the heart of the conflicts and a key to understanding why these business organisations were unsuccessful. That is, who or what is given meaning as �being green� negates and de-legitimates other activity that is not deemed to be green. In these conflicts business organisations extracting natural resources and subjects supporting these organisational activities could not be green - when being green was constituted in terms of the clean green discourse operating economically and socially within New Zealand (see Bell, 1996). Consequently, not being green was deemed to be outside of what we see as New Zealanders as being important and thus should not occur in this country. This research has implications for business organisations in New Zealand dealing with greening issues, especially as external stakeholders can have considerable influence on organisational activities. Theoretically it argues for a discursive approach to organisational stakeholder analysis in order to address power and subjectivity and for the organisation and natural environment literature to recognise the possibility of multiple meanings of nature. In particular, this thesis contributes to current organisation studies literature by explicitly focusing on �nature� as a concept. It shows that the meaning attributed to nature is a political process which can have consequences for preventing or enabling significant business organisational activities.
25

The Kaati Mamoe hapuu of Mahitahi : a question of mana?

Stevens, Emma, n/a January 1994 (has links)
Kaumaatua of the Te Koeti Turanga hapuu (sub-tribe) of South Westland have expressed concern that the mana of their Kaati Mamoe ancestors has been trampled on and their identity subsumed through union with the Kai Tahu tribal confederation. The history of the Kaati Mamoe iwi in the South island has been marginalised by the subsequent arrival of a number of hapuu of the Ngaati Kahungunu in the seventeenth century. The conflict which ensured following this gradual migration has traditionally been interpreted as marking the end of a Kaati Mamoe identity in the island. Complexity has been added to this situation as a result of European colonisation in the nineteenth century. The purchase by Pakeha of vast tracts of land in the South Island, and the failure to exempt the reserves promised, put pressure on the takata whenua�s land base and resources. The Crown�s refusal to acknowledge and redress the grievances of South Island Maori over the last hundred years has obliged the Kaati Mamoe to unite with the Kai Tahu. This process has served to further marginalise their identity, in this case in the southern rohe of the West Coast. The method that I have used in this work draws upon a number of disciplines. Oral history and written records of the Te Koeti hapuu form the central sources and to this extent this work may be described as being written from a Kaati Mamoe perspective. I have undertaken a review of the material recorded by European collectors of South Island Maori tradition in order to understand the way in which their reports have shaped the European view of South Westland Maori. And finally a review of the archaeological record has been included in order to provide information about the everyday material life of the ancestors of the South Westland hapuu. A number of conclusions have been reached in this thesis. Firstly that the peace arrangement at Popoutunoa which has been viewed by Kai Tahu as marking the end of a Kaati Mamoe identity is not necessarily the view of many Kaati Mamoe descendants. The historical record shows that a number of individuals continued to fight the Kai Tahu due to tribal differences while others continued to live alongside Kai Tahu in peace. As throughout much of Aotearoa, the importance of the hapuu as a source for an individual�s identity in Maori society prior to European colonisation has been over-shadowed. In the case of the South Westland people union with Kai Tahu, which was vital in the face of the loss of land, has been interpreted as the loss of their affiliation and identity with Kaati Mamoe.
26

Distribution of Hector�s dolphin (Cephalorhynchus hectori) in relation to oceanographic features

Clement, Deanna Marie, n/a January 2006 (has links)
Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin. Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally. To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data. Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area. The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.
27

Challenges that offenders face upon release that contribute to recidivism in the Department of Correctional Services: a case study of the West Coast Medium ' A' Correctional Centre in the Western Cape

Samuels, Jerome Alex January 2010 (has links)
Magister Artium - MA / Recidivism, the tendency to revert to crime upon release from prison, seems to be an uncontrollable phenomenon as inmates keep on re-offending, which impacts negatively on the already overcrowded correctional centres in South Africa. Life in prison is harsh and overpopulation leads to numerous communicable diseases such as tuberculosis, HIV/AIDS and other sexuality transmitted infections. Offenders participate in various rehabilitation programmes during their incarceration. However, the challenge is to sustain these rehabilitation efforts after their discharge from prison. Offenders released into society face numerous obstacles such as the need for employment, food, shelter, and the stigma of having been imprisoned. The community is reluctant to receive perpetrators back into society after their release from prison. Consequently, ex-offenders struggle to find employment because of this stigma, which often translates into family break-ups. They are then expected to invent new ways of making a living and surviving without any help from society; in, they resort to crime, which in turn results in recidivism. The research comprises an exploratory study of the challenges that offenders face upon release and which contribute to recidivism in the Department of Correctional Services (DCS). The West Coast Medium ‘A’ Correctional Centre in the Western Cape has been selected as the case study area. Although offenders attend various rehabilitation programmes inside the prison, it has become apparent that upon their release this rehabilitation is not sustained. The qualitative methodology used for this research included semi-structured interviews in order to gather information on the challenges that contribute to recidivism. Offenders, parolees, family members, the Head of Social Reintegration, a social worker, a representative of NICRO, the Chairperson of the Atlantis Community Police Forum, and a spokesperson for SAPS Atlantis were interviewed in order to gather the relevant information. / South Africa
28

Ecology and ecophysiology of Zostera capensis: responses and acclimation to temperature

Lawrence, Cloverley Mercia 28 January 2021 (has links)
This study aimed to understand the ecology of the threatened, habitat-forming seagrass, Zostera capensis in Langebaan Lagoon, a marine protected area that forms part of the West Coast national park, South Africa; and the physiological strategies that allow this habitat to persist in sub- and supra-optimal temperatures. First, the environmental drivers responsible for spatial and temporal variability in Zostera and its associated macro-epifauna were determined. Secondly, the effects of temperature and the role of algal grazing in maintaining seagrass performance under temperature stress were investigated. Seasonal field collections of seagrasses and their associated macro-epifauna were undertaken, along with regular measurements of key environmental variables. Thereafter, mesocosm experiments were performed to measure the responses of Zostera to thermal stress and grazing using morphometry, fluorometry, chromatography and biochemistry. Significant seasonal variability in seagrass distributions with severe diebacks in summer were found, which influenced associated macro-epifauna communities. Populations responded to environmental stress by changing their growth form producing small-leaves in high densities in the high intertidal, while those in low intertidal and subtidal areas produced sparse, large-leaved populations. These distinct populations supported unique faunal diversities, which were dominated by grazing invertebrates. Temperature was a consistent driver of seagrass density and leaf size, while turbidity and exposure were key environmental factors that influenced macro-epifaunal patterns. Macro-epifaunal abundances were highly positively correlated with seagrass leaf width and biomass. Different growth forms displayed different responses to thermal stress, including a higher photosynthetic rate, and accumulations of carbon and nitrogen as phenolic compounds, in small- compared to large-leaved plants. This implies that large-leaved populations are more vulnerable to stress from fouling, which was evident in their larger epiphyte loads, compared to small-leaved populations. In addition, grazers were ineffectual at regulating epiphyte growth which increased under warming conditions. These findings suggest differences in resilience between sub-populations of Zostera, and attest to their capacity to recover from environmental stress. They further emphasise the significance of identifying characteristics and acclimation strategies that allow habitats to persist under climate change, and thus sustain biodiversity and productivity, as well as continue to provide important ecosystem services.
29

Assessment of managed aquifer recharge using GIS based modeling approach in West Coast, South Africa

Zhang, Heng January 2019 (has links)
Philosophiae Doctor - PhD / Due to climate change, rapid urbanization, and population expansion, the water demand and supply is showing increasing fluctuations, especially in the arid or semi-arid regions. One of the most important water resource management strategies to improve water security in these drought-prone areas is managed aquifer recharge (MAR), which is developed to recharge groundwater purposefully and increase its storage to overcome the temporal imbalance between local water demand and availability, thus improving water security of the water supply. Assessment of an MAR project requires the integration of many types of methods, data and information from many disciplines, which makes it a challenge. This thesis addressed a GIS based modeling approach for assessing the implementation of MAR in terms of suitable sites as well as appropriate scheme in drought-prone area. The West Coast of South Africa was studied as a case. Langebaan Road
30

The effects of ocean acidification and temperature change on the West Coast rock lobster (Jasus lalandii)

Knapp, Jarred Lee 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The West Coast rock lobster (WCRL), Jasus lalandii, is a critical marine fisheries resource for South Africa and may in future be negatively affected by the changes in seawater parameters associated with the ongoing anthropogenic carbon dioxide (CO2) emissions. These CO2 emissions have been linked to a global decrease in ocean pH (termed “ocean acidification”) and an increase in temperature. There are strong estimates that these changes are to worsen in coming centuries. This warranted research because of 1) the low current level of the resource (2.6% of pristine) and 2) the relatively unexplored physiological- and other biological responses of the WCRL to environmental stressors. This information is essential for the sustainable management of the resource by government scientists in times of global- and regional climate change. In the short term, it was found that the WCRL was able to rapidly and reversibly respond to acute changes in seawater pH (pH 7.4), this was achieved primarily through the active up-regulation of bicarbonate levels in the haemolymph. Maintaining extracellular pH protects oxygen transport mechanisms, which are sensitive to pH changes due to the large Bohr effect that this study also revealed, in the respiratory protein, haemocyanin of adult WCRL. The energy cost of actively maintaining extracellular pH, however, is expected to affect growth and potentially survival in the long term. This was tested on juvenile WCRL that were exposed to a reduced seawater pH of 7.3 (18.8 °C) over a period of 28 weeks. Results revealed that survival was not influenced and acid-base regulation in the hypercapnia-exposed lobsters was maintained throughout the duration of the trial, however, this led to a reduced growth rate. Subsequently, in order to replicate field conditions more closely, a combination of effects, namely seawater pCO2 (pH 8 and 7.3) and different temperatures (15.6 and 19 °C) on the growth of juvenile WCRL were assessed over an exposure period of 48 weeks in a second chronic trial. In contrast to the initial trial (28 weeks), where hypercapnia was assessed separately, lobsters exposed to hypercapnia had a higher growth rate than those at the same temperature exposed to a “natural” (normocapnic) seawater pH. The difference was interpreted as an indication that food availability/quality may negatively affect stress response, as feeding in the first trial was later considered “sub-optimal” in comparison to that of the second trial. In the latter, although both hypercapnia and temperature affected growth rates, temperature was the largest contributor to differences observed between treatments. The order of growth rates for lobsters from different treatments was: hypercapnia/high temperature > normocapnia/high temperature > hypercapnia/low temperature > normocapnia/low temperature. In this trial too, irrespective of treatment, lobsters were able to maintain extracellular pH within a relatively narrow range over the extent of the trial and survival was not negatively affected by hypercapnia or high temperature. In order to compare the sensitivity of juvenile WCRL to that of adults, with regards to the effect of changes in extracellular pH on oxygen transport, and to assess the impact of chronic hypercapnia, haemocyanin from juveniles was studied in detail after the first growth trial. This revealed that juvenile WCRL have a similar Bohr effect to that of adults. In addition, the haemocyanin of hypercapnia-exposed juveniles showed an increased affinity to oxygen caused by an intrinsic change in its molecular structure. This was interpreted as an energy-saving mechanism, because at the same time, haemocyanin concentration in these animals was lower than in normocapnic lobsters. At the termination of the second chronic trial, the immunological response to the combined stressors was assessed, namely total circulating haemocyte counts (THC) and the ability to clear/inactivate an introduced dose of a bacterium, Vibrio anguillarum. A pilot experiment on non-treated juveniles revealed a similar resting THC to that of other lobster species, and culturable V. anguillarum was rapidly cleared from their haemolymph. The effect of chronic exposure to a combination of effects, namely hypercapnia and different temperatures, was subsequently tested after termination of the second chronic trial. There were no differences between treatments in a) baseline THC (i.e. before bacterial challenge) and 2) the capability to clear culturable bacteria from haemolymph. The only difference was the circulating THCs post-bacterial challenge, as they were reduced in the hypercapnic-, high temperature treatment, compared with all other treatments. The reason is unknown, but it is speculated that it may have been linked to an increased metabolic demand in these lobsters. Overall, these results demonstrate the great plasticity of the WCRL at the molecular-, biochemical and physiological level. They provide important initial information for government fisheries scientists to aid in predicting future development of, and potential threats to the WCRL resource, as well as providing a platform from which the direction of future studies can be determined. / AFRIKAANSE OPSOMMING: Die Weskus-seekreef, Jasus lalandii, is ’n belangrike seevisseryhulpbron vir Suid-Afrika en kan in die toekoms negatief geraak word deur die veranderinge in seewaterparameters wat met voortgesette antropogeniese vrystellings van koolstofdioksied (CO2) verband hou. Hierdie CO2-vrystellings word met ’n wêreldwye daling in die pH van seewater (oftewel “oseaanversuring”) en ’n temperatuurstyging verbind. Alles dui daarop dat hierdie veranderinge in die volgende eeue sal vererger. Dít regverdig navorsing weens 1) die huidige skaarste aan dié hulpbron (2,6% van oorspronklike getalle), en 2) die betreklik onverkende fisiologiese en ander biologiese reaksies van die kreef op omgewingstressors. Hierdie inligting is noodsaaklik om staatswetenskaplikes in staat te stel om die hulpbron te midde van wêreldwye en streeksklimaatsverandering volhoubaar te bestuur. Op kort termyn word daar bevind dat die Weskus-kreef vinnig en omkeerbaar op akute veranderinge in die pH van seewater reageer (pH 7,4). Dít is hoofsaaklik deur die aktiewe opwaartse regulering van bikarbonaatvlakke in die hemolimf vasgestel. Die handhawing van ekstrasellulêre pH beskerm die meganismes wat suurstof vervoer, wat gevoelig is vir pH-veranderinge weens die beduidende Bohr-effek in die respiratoriese proteïen, hemosianien, by die volwasse kreef – nóg ’n bevinding van hierdie studie. Tog sal die energiekoste verbonde aan die handhawing van ekstrasellulêre pH na verwagting groei en moontlik ook oorlewing op lang termyn beïnvloed. Dít is getoets op jong Weskus-krewe wat oor ’n tydperk van 28 weke aan seewater met ’n verlaagde pH van 7,3 (18,8 °C) blootgestel is. Resultate dui daarop dat oorlewing nié geraak word nie, en dat suur-basis-regulering in die hiperkapnie-blootgestelde krewe vir die volle duur van die proef gehandhaaf is, hoewel dit tot ’n verlaagde groeitempo gelei het. Ten einde natuurlike omstandighede akkurater na te boots, is ’n kombinasie van uitwerkings, naamlik pCO2 van seewater (pH 8 en 7,3) en verskillende temperature (15,6 en 19 °C), op die groei van jong krewe oor ’n blootstellingstydperk van 48 weke in ’n tweede chroniese proefneming beoordeel. In teenstelling met die aanvanklike proef (28 weke), is hiperkapnie afsonderlik beoordeel en het krewe wat aan hiperkapnie blootgestel is ’n hoër groeitempo getoon as dié by dieselfde temperatuur wat aan seewater met ’n ‘natuurlike’ (normokapniese) pH blootgestel is. Dié verskil is vertolk as ’n aanwyser dat voedselbeskikbaarheid/-gehalte ’n negatiewe uitwerking op stresreaksie kan hê, aangesien voeding in die eerste proefneming later as ‘suboptimaal’ beskou is vergeleke met dié van die tweede proef. In die tweede proef, hoewel hiperkapnie én temperatuur groeitempo’s beïnvloed het, was temperatuur die grootste bydraer tot die verskille wat tussen behandelings opgemerk is. Die orde van die kreefgroeitempo’s met die verskillende behandelings was: hiperkapnie/hoë temperatuur > normokapnie/hoë temperatuur > hiperkapnie/lae temperatuur > normokapnie/lae temperatuur. In die tweede proef kon die kreef ook, ongeag behandeling, ekstrasellulêre pH vir die volle duur van die proefneming binne ’n betreklik beperkte bestek handhaaf, en het nóg hiperkapnie nóg hoë temperatuur ’n negatiewe invloed op oorlewing gehad. Om die gevoeligheid van jong Weskus-krewe met dié van volwasse krewe te vergelyk wat betref die uitwerking van veranderinge in ekstrasellulêre pH op suurstofvervoer, en om die impak van chroniese hiperkapnie te bepaal, is die hemosianien van jong krewe deeglik ná die eerste groeiproef bestudeer. Dít het aan die lig gebring dat die jong kreef ’n soortgelyke Bohr-effek as volwassenes toon. Daarbenewens toon die hemosianien van hiperkapnie-blootgestelde jong krewe ’n verhoogde affiniteit tot suurstof, wat deur ’n intrinsieke verandering in molekulêre struktuur veroorsaak word. Dít is as ’n energiebesparingsmeganisme vertolk, aangesien hemosianienkonsentrasie by hierdie diere terselfdertyd laer was as by normokapniese kreef. Aan die einde van die tweede chroniese proefneming is die immunologiese reaksie op die gekombineerde stressors beoordeel, naamlik totale sirkulerende hemosiettellings (THC) en die vermoë om ’n toegediende dosis van die bakterie Vibrio anguillarum op te ruim/te deaktiveer. ’n Toetseksperiment met niebehandelde jong krewe dui op ’n soortgelyke rustende THC as dié van ander kreefspesies, en kweekbare V. anguillarum is vinnig uit die hemolimf opgeruim. Die effek van chroniese blootstelling aan ’n kombinasie van faktore, naamlik hiperkapnie en verskillende temperature, is vervolgens na afloop van die tweede chroniese proef getoets. Die verskillende behandelings lewer dieselfde a) THC op die basislyn (met ander woorde voor toediening van die bakterie), en 2) opruimingsvermoë van kweekbare bakterieë uit die hemolimf op. Die enigste verskil was die THC’s ná toediening van die bakterie, wat laer was met die hiperkapniese hoëtemperatuurbehandeling as met alle ander behandelings. Die rede hiervoor is onbekend, maar hou vermoedelik verband met ’n verhoogde metaboliese vereiste by hierdie krewe. Oor die algemeen toon hierdie resultate die beduidende plastisiteit van die Weskus-seekreef op molekulêre, biochemiese en fisiologiese vlak. Dit bied belangrike aanvanklike inligting vir staatsvisserywetenskaplikes om die toekomstige ontwikkeling van én moontlike bedreigings vir die kreefhulpbron te voorspel, en voorsien boonop ’n platform van waar die rigting van toekomstige studies bepaal kan word.

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