Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2000. / Härtill 5 uppsatser.

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Geólogo / En la zona norte de Chile entre los 20º30 S y 20º45 S aproximadamente, se encuentra la Cuenca del Salar de Coposa. Esta cuenca al igual que otras cuencas aledañas posee las características adecuadas para el depósito de sales. Actualmente en esta zona se explota agua para el abastecimiento de faenas mineras. En este estudio se pretende describir detalladamente el registro estratigráfico de la zona nor-este de la cuenca, determinando como se forman las distintas unidades que se puedan reconocer. Para esto se analizan macroscópica y microscópicamente 3 sondajes diamantinos profundos, llamados DEC-04, DEC-05 y DEC-06. Hacia la base de los tres pozos aparece una toba cristalina que se correlaciona con la Ignimbrita Huasco, con una edad miocena media. Se observa que el techo de esta unidad se eleva hacia el sur. Sobre la toba cristalina se observa una brecha volcano-sedimentaria compuesta por clastos de origen volcánico y plutónico, mal seleccionados. Esta brecha es correlacionable con los depósitos aterrazados Tt de edad miocena tardía-pliocena temprana (Victor, 2004). Sobreyaciendo a esta unidad se encuentra la secuencia volcano-sedimentaria (inferior), compuesta principalmente por arenas medias y cenizas. Es común observar en este nivel laminación y retrabajo. Sobre estos depósitos destaca la presencia de la sucesión sedimentaria evaporítica en los pozos DEC-04 y DEC-05, en la cual se distinguen sulfatos de calcio, niveles clásticos y piroclásticos (principalmente ceniza). En esta unidad es posible reconocer como ambientes de formación sabkhas y lagos playa conviviendo con un arco activo con actividad explosiva. Los sulfatos de calcio encontrados corresponden a yeso y anhidrita. Es común observar en el microscopio cristales de yeso transformándose a anhidrita. Este tipo de depósitos se ve interrumpido aproximadamente a los 3.600 m s.n.m. donde nuevamente se observa una secuencia volcano-sedimentaria. Tanto en la brecha volcano-sedimentaria como en la secuencia volcano-sedimentaria (inferior) se encontró anhidrita como cemento. Es posible encontrar, además, entre los depósitos antes mencionados distintos niveles piroclásticos y depósitos volcánicos como lavas andesíticas y brechas volcánicas. Ya hacia la superficie aparece la Ignimbrita Pastillos y depósitos no consolidados.

Geóloga / La región de Atacama presenta sectores que poseen condiciones sumamente hostiles para la vida, la combinación entre un clima extremadamente árido con la alta radiación UV que recibe, lo ha instalado dentro de la comunidad científica como un potencial análogo terrestre a la superficie marciana, en el que además, se han reportado microorganismos y componentes orgánicos. Bajo este contexto se desarrolla este estudio, el cual analiza al salar Azufrera y a un sistema hidrotermal en sus cercanías, ambos ubicados en la parte noreste de la región, específicamente en el sector más cordillerano, donde si bien las condiciones imperantes no son tan adversas como las que se encuentran en el desierto de Atacama como tal, sí lo son para el desarrollo de la vida. El objetivo de este trabajo es caracterizar los fluidos que permiten la posible existencia de microorganismos en estos depósitos, intentar bosquejar su evolución y compararlos con fluidos que eventualmente podrían existir en la superficie marciana. Para esto se requiere una recopilación representativa de las zonas a estudiar, luego una caracterización petrográfica de los minerales de la zona y de las inclusiones fluidas primarias y secundarias que hayan albergado idealmente microorganismos. Con los datos obtenidos de estos procedimientos se realiza un análisis microtermométrico para determinar la composición de los fluidos. Se identificaron en las muestras del salar Azufrera diatomeas, coccis, algas y componentes orgánicos. Sin embargo, las inclusiones que aportan información válida para este estudio, lamentablemente no contienen ni microorganismos ni materia orgánica. Además un gran porcentaje de las inclusiones resultaron ser metaestables, lo cual imposibilitó la obtención de datos de un gran número de FIAs. En el sistema hidrotermal se encontraron filamentos, diatomeas e insectos alados afuera de las inclusiones desafortunadamente, por lo tanto no fue posible caracterizar los fluidos que permitieron su existencia en este sistema. Con el software Frezchem se modelaron los fluidos primarios del salar Azufrera y se intentó estimar la concentración de estos en un ambiente similar a Marte. Las condiciones ambientales fueron modeladas con pH 7.7 y 3.0. El pH neutro prevalece en el suelo marciano (Marion et al. (2010)) y en la mayoría de los salares de la zona de estudio; el pH ácido se justifica por la presencia de jarosita en Marte y la presencia de alteraciones hidrotermales en la tierra. Los resultados indican que las composiciones iónicas son tres órdenes de magnitud diferentes y por lo tanto poco comparables, además las variaciones en el pH no tendrían repercusiones en las concentraciones iónicas, no obstante, bajo ambos escenarios podría precipitar yeso, mineral con propiedades que permiten la preservación adecuada de microorganismos bajo condiciones adversas. Dado lo anterior no es posible concluir tajantemente al respecto.

Lax är en av de mest frekvent förekommande matfiskarna i våra hem. Den största delen av den lax som når hem och restaurang är odlad. Det är allt vanligare med sjukdomar hos lax som odlas. Kocken ställs inför svåra frågor gällande den odlade fiskens kvalité. En viktig aspekt är att ha kunskap om de eventuella sjukdomar som förekommer i vår samtids fiskodling. Syftet med detta arbete är att undersöka den i vardagens måltider förekommande råvaran odlad lax utifrån hur sjukdomar påverkar fiskens kvalité. Den information som ges i de fem vetenskapliga artiklar arbetet är baserat på presenteras i avsnittet resultat. Det framgår att en stressad och sjuk fisk tappar avsevärt i kvalité och ger en sämre avkastning. I diskussionen jämförs olika författares resultat och det framgår här att bättre foder, smittokontroll och högre levnadsstandard för laxen ger en bättre produkt ur kvalitetssynpunkt. Slutsatserna som dras är att vi tillagar en fisk med sämre kvalité än nödvändigt och att vi för denna betalar ett högre pris än nödvändigt. Litteraturstudien bygger på fem vetenskapliga artiklar från olika databaser, litteraturen redovisas i resultatet och databassökningarna i sökmatriser. Sammanfattningar av de fem artiklarna återfinns i artikelmatriser i slutet av arbetet. / B-uppsatser

The structuring of Atlantic salmon (Salmo salar L.) into discrete, genetically differentiated populations both within and between river catchments is well documented. The utilisation of this knowledge has proved valuable in a variety of evolutionary, ecological, managerial and conservation contexts. In this thesis, the genetic structuring of Atlantic salmon populations in northwest Europe was assessed in two catchments of very different sizes, using a range of molecular and associated population genetic methods; findings from the catchment level research are set in context by a broader phylogeographic study of post-glacial colonisation of the region. A regional study into the glacial origins and post-glacial colonisation routes of Atlantic salmon in northwest Europe was explored by analysing a pre-existing microsatellite dataset and supplementing it with haplotype data from mtDNA PCR-RFLP analysis of the same samples (N=702). Evidence from allele permutation tests undertaken on the microsatellite data alongside mtDNA haplotype frequencies suggested that there was a cryptic northern refuge in northwest France, with colonisation of the British Isles and Ireland occurring from this and the long-known Iberian Peninsula refuge. Catchment level studies were undertaken on the river Dart and river Tweed, involving 1151 fish being genotyped with 14 microsatellite loci with a subset of 211 fish being genotyped by mtDNA PCR-RFLP. In both catchments, populations were found to be weakly differentiated genetically, and were most consistent with the meta-population theory of evolution. Similarly, individual spatial autocorrelation analysis indicated that each major tributary within the catchments could be considered as a distinct management or conservation unit. In the Tweed dataset, however, limitations in the sample coverage across the catchment reduced the robustness of some findings. Historical stocking of the river Dart with fish from Scotland and Iceland is well-documented. The long-term implications of these activities on contemporary Dart populations were assessed by genotyping 177 fish from the donor populations using scale samples taken in the 1960s and comparing them to contemporary Dart populations by undertaking admixture analysis. Overall, admixture between the donor and recipient populations was low and appeared to reflect natural underlying levels of genetic relationships. However, increased admixture of donor stocks with one extant Dart population was apparent, indicating some potentially long-term localised success of the stocked fish through hybridisation with the native populations; nevertheless, with the population continuing to decline, this should not be viewed as a successful supplementation programme. Two tributaries on the river Tweed, the Gala and Leader, were inaccessible to salmon for long periods due to the construction of barriers to migration. On both tributaries, fish passes were installed in the 1940s and re-colonisation of the tributaries was possible. Assignment analysis was undertaken and indicated that, contrary to findings for between catchment studies, salmon straying from the most proximate tributaries (i.e. the Ettrick and Caddon) did not appear to be the principal colonisers of the current Gala and Leader populations. Rather, the highest proportion of Gala samples assigned to the Teviot (42%), with the Leader populations assigning to many tributaries across the catchment (Ettrick 28%; Upper 21%; Teviot 19%). However, given the relatively weak differentiation of the baseline samples and limitations inherent in the dataset, the correct self-assignment of baseline samples was very low (average 26%; range 0-47%), hence interpretation must be undertaken with caution. Nevertheless, the findings suggest that the Gala population may have reached a temporally stable state in the 60 years since it has been accessible to salmon. Whilst the relatively small scale of these studies is acknowledged, the application of the findings in management and conservation of the species are discussed in a wider context. These studies would support the following recommendations: to include information on the historic (refugial) origin of contemporary populations in regional management strategies; to treat each major tributary as a distinct unit as an appropriate scale for catchment level management; and, with stocking and supplementation programmes appearing to have no significant long-term success, coupled with the relative speed with which extirpated tributaries appear to be naturally re-colonised, the use of stocking and supplementation programmes should be discouraged.

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Individual variation and limited plasticity in behavior are factors that have been shown to shape populations and determine how well individuals are doing in different stages of life. When salmon transform from parr to smolt and start the migration out to sea many factors together make an individual successful. The hypothesis of this study was that the boldness of individual smolt (1 and 2 year olds) is correlated to their inclination to migrate downstream. The study also investigated difference in boldness and migration tendency between 1- and two year old smolt. Today, some hatcheries release smolt as both one and two year old and it is important to know whether there is any difference in behavior and migration intensity between age classes in order to make stocking programs more effective. To determine if the individuals differed in boldness, and/or displayed a bold behavioral type, two assays were performed in different contexts (novel environment and simulated predatory attack). Downstream migratory intensity was, after behavior assays, quantified in an artificial stream. I found that: i) the one year old smolts tended to be bolder in a predatory response assay than two year old smolt, ii) one year old smolts migrated less in the artificial stream compared to two year old smolt. Being bolder can have an effect on several aspects connected to fitness in the salmon life cycle and could affect the survival of a smolt migrating out to sea, even though no correlations to inclination to downstream migration were found in this study.

For Atlantic salmon (Salmo salar) and brown trout (Salmo trutta), the decision to migrate or when to migrate is believed to be influenced by the individual’s metabolic rate (MR) relative its food intake. As MR was expected to be related to behaviour, the potential links between behaviour and metabolic costs was studied. For both salmon and trout the dominant individual had a higher standard metabolic rate (SMR) than its subordinate counterpart. Also, successful migrants of brown trout had a higher SMR than unsuccessful migrants, whereas no such difference was found for obligate migratory Atlantic salmon. Measures of variation in MR and boldness indicated that Atlantic salmon was more sensitive to stress than brown trout and became passive when stressed. When two trout were interacting, an increase in ventilation rate (VR) was positively correlated to fighting intensity. The first day after an interaction, VR did not differ between small dominant and subordinate trout (mean size 3.7g), whereas for large trout (26.0g) subordinates had higher VR than dominants. However, a combination of low temperature (10°C) and high water velocity (22cm/s) eliminated this difference. This probably reflects the high swimming activity of small dominants and the low motivation for dominants to defend a large territory when temperatures were low and the cost of moving was high. These results show that the relationship between MR and behaviour may differ depending on species, fish size and environmental factors.