Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

River herring, collectively alewives (Alosa pseudoharengus) and blueback herring (A. aestivalis), have experienced substantial population declines over the past five decades due in large part to overfishing, combined with other sources of mortality, and disrupted access to critical freshwater spawning habitats. Anadromous river herring populations are currently assessed by counting adults in rivers during upstream spawning migrations, but no field-based assessment methods exist for estimating juvenile densities in freshwater nursery habitats. Counts of 4-year-old migrating adults are variable and prevent understanding about how mortality acts on different life stages prior to returning to spawn (e.g., juveniles and immature adults in lakes, rivers, estuaries, and oceans). This in turn makes it challenging to infer a link between adult counts and juvenile recruitment and to develop effective management policy. I used a pelagic purse seine to investigate juvenile river herring densities, growth, and mortality across 16 New England lakes. First, I evaluated the effectiveness and sampling precision of a pelagic purse seine for capturing juvenile river herring in lakes, since this sampling gear has not been systematically tested. Sampling at night in June or July resulted in highest catches. Precision, as measured by the coefficient of variation, was lowest in July (0.23) compared to June (0.32), August (0.38), and September (0.61). Simulation results indicated that the effort required to produce precise density estimates is largely dependent on lake size with small lakes (<50 >ha) requiring up to 10 purse seine hauls and large lakes (>50 ha) requiring 15–20 hauls. These results suggested that juvenile recruitment densities can be effectively measured using a purse seine at night in June or July with 10–20 hauls. Using juvenile fishes captured during purse seining in June–September 2015, I calculated growth and mortality rates from sagittal otoliths. Density, growth, and mortality were highly variable among lakes, and mixed-effects regression models explained 11%–76% of the variance in these estimates. Juvenile densities ranged over an order of magnitude and were inversely related to dissolved organic carbon. Juvenile growth rates were higher in productive systems (i.e., low secchi depth, high nutrients) and were strongly density-dependent, leading to much larger fish at age in productive lakes with low densities of river herring compared to high density lakes. Water temperature explained 56%–85% of the variation in juvenile growth rates during the first 30 days of life. Mortality was positively related to total phosphorous levels and inversely related to hatch date, with earlier hatching cohorts experiencing higher mortality. These results indicate the importance of water quality and juvenile densities in nursery habitats for determining juvenile growth and survival. This study encourages future assessments of juvenile river herring in freshwater and contributes to an understanding of factors explaining juvenile recruitment that can guide more effective and comprehensive management of river herring.

Hot peppers are gaining popularity in the United States as both a vegetable and a spice. In 2008, jalapeño peppers were involved in a multistate outbreak of Salmonella Saintpaul. This is the first outbreak implicating jalapeño as a vehicle for foodborne illness. Hot peppers contain many compounds thought to possess antimicrobial characteristics. This research was conducted to provide more information on the interactions of pathogenic bacteria and jalapeño peppers, as well as to identify properties of Capsicum annuum that affect bacterial survival, growth, and inhibition. Behavior of pathogens associated with jalapeños was investigated by inoculating jalapeño fruits with a cocktail of Listeria monocytogenes, Salmonella enterica, or Escherichia coli O157:H7 on the intact external surface, injured external surface, or intact internal cavity and storing the jalapeños at 7°C or 12°C. Intact external jalapeñosurfaces did not support the growth of the bacteria tested under storage conditions of 7°C. However, L. monocytogenes populations remained detectable throughout the 2 week study. At 7°C, pathogenic bacteria were able to survive but not grow on injured and internally inoculated jalapeño, but populations increased at 12°C (p=0.05). The most supportive growth environment for the pathogenic bacteria was the internal cavity of jalapeño held at 12°C. This study demonstrated the importance of intact uninjured produce and proper storage temperatures for food microbial safety. Inhibitory properties of jalapeños were studied by making extracts from fresh jalapeño peppers to test for antimicrobial activity. A disk diffusion assay determined that the extracts were capable of inhibiting the growth of the pathogenic bacteria tested. Listeria monocytogenes was especially sensitive to the extracts. jalapeño extracts were fractionated using HPLC and used for inhibition assays using disk diffusion and growth curve generation. Two fractions stimulated bacterial growth (p=0.05), while two other fractions inhibited bacterial growth. The inhibitory fractions were separated further using HPLC and tested for antimicrobial activity. Fraction E1 suppressed the growth of L. monocytogenes. HPLC-MS analysis revealed that Fraction E1 contained compounds known as capsianosides. To prove that inhibition is caused by capsianoside(s) and determine minimum inhibitory concentrations, a method to isolate the pure compound should be developed. / Ph. D.

The research assessed the potential of developing a selective breeding programme for the UK rainbow trout industry. Levels of genetic variation at 12 microsatellite loci were first compared in seven different commercial strains. The Observed heterozygosity ranged from Ho = 48.1% in a gold rainbow trout strain (GTR) to Ho = 66.4% in a newly derived broodstock population constructed from a number of different sources (GIT). The Expected Heterozygosity (He) was highest in GIM1 (He= 79.5%) and lowest in the GTR strain (He = 56.9%). The Effective number of alleles (Mae) showed that the GIM1, GIM2, GIM3, and GIT strain (5.4; 5.2; 4.8; 4.2) were significantly more variable than the other strains and that GTR strain had the lowest value (2.5). There appears to be substantial genetic variability within the commercial United Kingdom rainbow trout strains surveyed in this study. This appears to be the case despite very different management histories and levels of record keeping. The strains appear to be genetically distinct (based on population genetic analyses), though the reasons for this remain unclear (and possibly unanswerable given the poor records kept by the different companies). The Glenwyllin farm strains (GIM) were chosen to form the base population for the project because of their high genetic variability, disease free status and because the farm produced around 20 million ova per year, so any genetic gains would have a widespread impact. The farm has an early (Strain A) and a late spawning (Strain B) and these were mated in a partial factorial design, 20 females and 20 neomales per strain (A & B) were chosen on the basis of maturity and gamete quality in November 2002 so that each male was crossed to 4 females (2 in the same strain and 2 in the other), a total of 160 families were created. All broodstock were biopsied to enable them to be genotyped. The families were reared separately up to the eyed stage at which point the eggs from each family were divided into three to generate three communal replicate populations. One of these was sent to a fingerling producer (Iwerne Spring) for ongrowing to fingerling size and formed the basis of a commercial production trial at Test Valley Trout farm (TVT) in Hampshire. When the fish reached an average weight of 5 g they were transferred from Iwerne Spring to TVT and 1500 were randomly selected, PIT tagged and biopsied to enable them to be assigned to their family using 11 multiplexed microsatellite loci. Parental assignment was based on exclusion (FAP) but the results were compared with another parental assignment based on likelihood (PAPA). Of the 1500 offspring (OIM) PIT tagged 1242 82.8% could be assigned to a single family utilizing different combinations of more than 6 loci (6 to 11). The growth of the 1500 OIM fish was tracked throughout the grow out period before they were finally harvested and fully processed. The results of OIM strain at the end of the trial period were mean weight of 415.5 g, and a mean length of 314.5 mm. The visual measurement of colour gave a mean flesh colour values of 26.01 on the 20-34 scale (SalmoFan™), and 11.0 with the colotimetry evaluation of colour (a*). The heritability results for the IOM strain were 43 ± 9% for weight, 42 ± 9% for gutted, and 28 ± 8% for length. The heritability estimates for the visual colour variables were 19 ± 7% and when using the colorimeter, the red chromaticity (a*) heritability was 14 ± 6%. Therefore, the heritability results of the IOM strain indicate that there are opportunities of substantial and rapid improvement of the growth rate and flesh colour traits. Also no line effects were observed or indications of non-additive genetic variation. In contrast to these last results, the overall survival of the GIM strain from the time of the physical tagging with PIT until harvest was 52.8%, and survival heritability was extremely low, 3 ± 2%, hardly significant.

Die großflächige Umwandlung von tropischen Wäldern hat zu dramatischen Verlusten von Biodiversität und assoziierten Ökosystemdienstleistungen und –funktionen geführt. Indonesien ist ein besonders schwerwiegendes Beispiel für den Verlust von Waldflächen und Biodiversität. Landumnutzungen, in starkem Maße durch den Anbau von Ölpalmen vorangetrieben, stellen eine erhebliche Bedrohung für die außergewöhnlich hohe Biodiversität des Landes dar. Landwirtschaftssysteme, wie Agroforstsysteme, können hingegen genutzt werden, um die Biodiversität und Ökosystemfunktionen in von Ölpalmen dominierten Landschaften zu erhöhen. In Regionen, in denen Ölpalmplantagen bereits die Landschaft dominieren, kann diese Erhöhung nur durch systematische Renaturierung erfolgen. Die zugrunde liegenden ökologischen und soziökonomischen Prozesse und damit verbundene Beschränkungen und Kompromisse von Renaturierungsmaßnahmen in von Ölpalmen dominierten Landschaften sind jedoch weitgehend unbekannt. Um diese Wissenslücke zu schließen, habe ich mit Kollegen aus Deutschland und Indonesien ein Langzeitexperiment zur Erhöhung der Biodiversität aufgebaut. Wir haben experimentell Bäume in Form von „Inseln“ in eine konventionelle Ölpalmplantage gepflanzt und hierbei systematisch die Flächengröße, das Diversitätslevel und die Artzusammensetzung variiert. Wir haben hierfür sechs multifunktionale heimische Baumarten ausgewählt. Auf der Fläche der Bauminseln haben wir einen Teil der Ölpalmen gefällt, um die Lichtverfügbarkeit für die gepflanzten Bäume durch eine reduzierte Ölpalmdichte zu erhöhen. In dieser Doktorarbeit stelle ich den Aufbau des Experiments vor und gebe einen breiten Einblick in anfängliche Auswirkungen des Experiments, indem ich ökologische Aspekte in Betracht ziehe, sowie Veränderungen hinsichtlich des Ernteertrags. Da die Zeit kurz nach der Pflanzung ein Nadelöhr für die Langzeitetablierung der Bäume darstellt, ist sie sehr kritisch, um die erwünschten Renaturierungserfolge in der Zukunft zu erzielen. Des Weiteren kann die Anfangszeit auch aus der Sicht der Landwirte eine entscheidende Hürde darstellen, da der Nutzen der Bauminseln erst lange Zeit nach ihrer Pflanzung entsteht. Zuerst beschreibe ich Umweltvariablen und biotische Charakteristika der den experimentellen Flächen assoziierten Vegetation, Invertebraten und Vögel vor der Errichtung des Experiments, sowie anfängliche Auswirkungen des Experiments auf die Fauna. Ein Jahr nach der Errichtung des Experiments hatten die Baumpflanzungen einen insgesamt positiven Effekt auf die Artengemeinschaften von Vögeln und Invertebraten in der Plantage. Die Größe der Bauminseln wirkte sich lediglich auf die Diversität und Abundanz von Invertebraten positiv aus, die somit auf kleinskalige Veränderungen reagierten. Ausgehend von diesen Ergebnissen erwarte ich einen weiteren Anstieg der Biodiversität und Ökosystemfunktionen in der Zukunft. Danach berichte ich über den Anwuchserfolg der Bäume und ermittle die wichtigsten Determinanten für den Wuchs und das Überleben der Bäume. Insgesamt sind die Bäume gut angewachsen, jedoch gab es große Unterschiede zwischen den Baumarten hinsichtlich relativer Höhenwachstums-, Dickenwachstums- sowie Überlebensraten. Arten mit hohen Wachstumsraten wiesen vorwiegend auch hohe Überlebensraten auf. Auf Versuchsflächenebene hatten Standortbedingungen, Flächengröße und Diversitätslevel der gepflanzten Bäume lediglich einen geringen Einfluss auf das mittlere Baumwachstum und die Überlebensrate. Auf Individuenebene habe ich signifikante Nachbarschaftseffekte festgestellt. Hohe benachbarte Bäume und die Distanz zu verbleibenden Ölpalmen begünstigten die Entwicklung der Bäume. Noch ist es zu früh zu entscheiden, welche der Baumarten sich generell am besten eignen, um Renaturierungsziele zu erreichen. Unterschiede in der anfänglichen Entwicklung liefern jedoch wichtige Informationen für eine zukünftige Bewertung der Arten. Zuletzt präsentiere ich Auswirkungen des Experiments auf den Ölpalmertrag. Nach zwei Jahren waren die Erträge pro Ölpalmindividuum erhöht, sowohl auf als auch direkt neben den Versuchsflächen. Die geschätzten Ertragsänderungen für die verschiedenen Flächengrößen unter Einbezug von Ernteverlusten durch gefällte Ölpalmen sowie Effekte auf benachbarte Ölpalmen deuten darauf hin, dass die erhöhten Ernteerträge insbesondere in großen Bauminseln mindestens das Fällen von Ölpalmen kompensiert haben. Diese Ergebnisse, die in der frühen Phase der Bauminseletablierung erzielt wurden, sind vielversprechend für die Erarbeitung nachhaltiger Managementoptionen für Ölpalmplantagen, die ökologische und ökonomische Funktionen in Einklang bringen. Die anfänglichen Auswirkungen waren stärker und insbesondere aus ökonomischer Perspektive profitabler als ich erwartet habe. Die Nachbarschaftseffekte und die Auswirkungen der experimentell veränderten Variablen waren bislang jedoch überwiegend schwach. Ich erwarte, dass diese Auswirkungen mit der Zeit stärker ausgeprägt sein werden. Durch Erkenntnisse, die aus zukünftigen Langzeitbeobachtungen des Experiments, das ich in dieser Doktorarbeit vorstelle, gewonnen werden, können Wissenslücken geschlossen werden. Somit kann die Ausarbeitung von Managementrichlinien für von Ölpalmen dominierten Landschaften ermöglicht werden, die sowohl ökologisch verbessert als auch ökonomisch lohnenswert sind. Diese Doktorarbeit stellt einen wesentlichen Beitrag zur generellen Beurteilung des Experiments dar, wodurch darüber hinaus auch neue Erkenntnisse für die Renaturierungswissenschaft gewonnen werden können.

Knowledge of effective reef restoration techniques are necessary in this age of worldwide coral reef decline. Coral transplantation is a restoration technique employed after natural (i.e. hurricanes) and anthropogenic (i.e. vessel groundings) physical disturbance events. The study was conducted to compare the efficacy of propagating small colony fragments in laboratory and field conditions in terms of survival and growth. Fragment growth and survival were assessed for six scleractinian boulder corals common to Florida and Caribbean reefs: Montastraea annularis, M. cavernosa, Diploria clivosa, Siderastrea siderea, S. radians and Dichocoenia stokesii. Broken coral colonies were salvaged from vessel grounding sites and marine debris, fragmented into pucks and secured to travertine tiles. One hundred and fifty-three coral colony fragments were cultivated in an ex situ laboratory nursery and 133 coral colony fragments were cultivated in an in situ field nursery and monitored for 13 months. Survival of all colonies was 94%, with 98% survival in the laboratory treatment and 89% survival in the field treatment. Complete colony mortality was documented in three S. radians colonies, all in the laboratory treatment. All colony loss in the field treatment was due to colony pucks being detached from the tiles. Overall mean percent change in colony tissue area from initial to final monitoring events was calculated to determine growth. Across species, growth was greater in the laboratory treatment (76 ± 4 % SEM) in comparison to the field treatment (27 ± 5 % SEM). Positive growth was observed in D. clivosa, D. stokesii, M. annularis, M. cavernosa and S. siderea in the laboratory treatment. In the field treatment, D. clivosa, M. annularis and M. cavernosa were the only species that exhibited positive growth. Negative growth was observed in both the laboratory and field treatments for S. radians. In conclusion, colonies propagated in the ex situ nursery (laboratory treatment) had higher growth and survival than colonies propagated in the in situ nursery (field treatment). A critical acclimation period accomplished through the use of stable laboratory conditions will produce healthier, more secure coral colonies that may be used to repopulate disturbed reef sites.