Jellyfish blooms create problems worldwide, which may increase with global warming, water pollution, and over-fishing. Benthic polyps (scyphistomae) asexually produce buds and small jellyfish (ephyrae), and this process may determine the population size of the large, swimming scyphomedusae. Environmental factors that affect the asexual reproduction rates include food, temperature, salinity, and light. In the present study, polyps of Aurelia aurita (L.), originated from Tapong Bay, southwest Taiwan, were studied in different combinations of temperatures (T), light intensities (L), and salinities (S). In the T (20, 25, 30¢XC) ¡Ñ L (372, 56, and 0 lux) experiment which was with a 12 h light-12 h dark photoperiod, production of new buds decreased with warmer temperatures and stronger light intensity. Warm temperatures accelerated strobilation and increased the daily production of ephyrae. The proportion of ephyrae to total asexual reproduction (new buds + ephyrae) increased dramatically in warmer temperatures and stronger light. Survival period was reduced at the highest temperature. Strobilation did not occur at the lowest temperature in darkness. All measures of total asexual reproduction indicated that medium to high temperatures would lead to faster production of more jellyfish; however, continuous high temperatures might result in high polyp mortality. Light intensity affected asexual reproduction less than did temperature, only significantly accelerating the strobilation rate. Because the interactive effects of light and temperature were significant for polyp survival time and the production of jellyfish per polyp, combined light and temperature effects are likely important for strobilation in situ. In the T (27, 31, 35¢XC) ¡Ñ S (25, 30, and 35) experiment which was in dark environment, production of new buds decreased with higher temperatures and salinity. The proportion of ephyrae to total asexual reproduction (new buds + ephyrae) increased with warmer temperatures, but survival period was reduced at the highest salinity, and strobilation was substantially reduced, even though the temperature was warmer compared to the T ¡Ñ L experiment. Salinity affected asexual reproduction less than did temperature, only significantly affecting production of new buds, and slightly affecting survival period and the proportion of ephyrae to total asexual reproduction. According to these two experiments, warmer temperature may accelerate strobilation in light condition and lead to better yield of swimming jellyfish, however continuously warm temperature would reduce the yield by decreasing budding and higher mortality. Complete dark led to much less strobilation, especially at low temperatures, suggesting that the existence of light might be more important than light intensity. The effects of salinity on asexual reproduction were not as conspicuous as that of temperature and light.

Chrysaora fuscescens is a cnidarian scyphomedusa that occurs in the northern California Current. In this upwelling system, medusae are seasonally abundant, and individuals can ingest 10-60% of the standing stock of vulnerable zooplankton taxa per day. Yet little is known about this medusa's feeding ecology. Using laboratory pseudokreisels, C. fuscescens feeding rates and behavior were quantified in the presence of a controlled flow field. C. fuscescens collected aboard research cruises were dissected, and prey items were counted in order to calculate feeding rates and prey selectivity. In the lab, C. fuscescens feeding rates were not affected by shear flow, and medusa maintained position by swimming counter-current. Field work demonstrates high feeding rates and positive prey selection for nonmotile taxa. For the first time, high clearance rates of ichthyoplankton have been documented. An understanding of jellyfish behavior can help explain jellyfish distributions and trophic impacts in a productive upwelling system.

Jellyfish (Phylum Cnidaria, Class Scyphozoa) play important roles in pelagic ecosystems as predators and prey. Seasonally they form blooms facilitating reproductive success, but that are at times problematic for human enterprise. Medusa abundance has been correlated with environmental variables in several instances. However, the direct mechanisms for changes in medusa abundance are unclear. As global sea surface temperatures continue to change there is increasing concern that warming may enhance conditions favourable for the generation of jellyfish medusae. It is important to understand the ways in which temperature affects all life history stages of jellyfish if we are to begin to understand factors associated with jellyfish bloom formations, but how temperature and salinity affects life history stages of scyphozoan jellyfish from British waters remains largely unknown. In Chapter 1 I provide a general introduction to some key issues important to the formation of jellyfish blooms. In Chapter 2 I present results for experiments testing the effects of temperature on settlement and metamorphosis of planulae larvae of Cyanea capillata, Cyanea lamarckii, Chyrsaora hysoscella, and Aurelia aurita. Chapter 3 reports on the effects of temperature and salinity on survival, and asexual reproduction of scyphistomae of the same species. Chapter 4 reports on the effects of temperature and salinity on growth of newly released ephyrae of each of the above mentioned species, as well as the effects of starvation on survivorship on ephyrae of A. aurita originating from two distinct populations of scyphistomae. In Chapter 5 I provide a brief summary of significant findings for each life history stage, their theoretical implications when taken together, and next steps for future research. I also offer recommendations for ecosystem managers with an eye toward affecting the numbers of near-shore jellyfish medusae generated each season in the waters surrounding the British Isles.

>Magister Scientiae - MSc / Hydromedusae are mostly carnivorous planktivores that under ideal conditions can reproduce and accumulate to form dense masses of jellyfish, known as blooms. These jellyfish blooms may have various impacts on their surrounding biota and in severe cases have the potential to result in ecosystem-wide changes. This study investigated assemblages of hydromedusae within the southern Benguela ecosystem, between the years 2000 and 2006. The samples analyzed were collected as part of routine Spawner Biomass Surveys conducted by the Department of Environmental Affairs: Ocean and Coasts (previously Marine and Coastal Management) using Bongo nets. Two hundred and forty two of the samples collected during the spring months, October and November, were analyzed. Environmental variables including (amongst others) sea surface temperature (SST), sea surface salinity (SSS), sea surface oxygen (SSO) and fluorescence (as a proxy for Chlorophyll a concentration) were measured to observe their influence on medusoid assemblages, distribution, abundance and diversity. Assemblages of hydromedusae were represented by 69 species and were dominated by Siphonophora and Leptomedusae. Mean abundance of hydromedusae were highest in 2005 (3.15 ind.m-³, SD 3.21) and lowest in 2002 (0.50 ind.m-³, SD 0.70). Trends in abundance displayed a general bell-shaped curve relationship with SST. The random-effects meta-analysis model revealed, across all years and all medusaoid classes that SSS (R=0.469), latitude (R=0.223), bottom fluorescence (R=0.533), mean fluorescence (R=0.338) and volume filtered (R=-0.408) were all significant factors in driving medusoid abundance at p<0.05. Medusoid diversity displayed a positive correlation to both temperature and salinity. A BIOENV analysis was used to explore the environmental factors that best described the variation observed in the biological assemblages. The results from this analysis suggest that SSS and bottom oxygen (BO) are the environmental factors that most influence the composition of medusoid assemblages.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13339号 / 論農博第2882号 / 新制||農||1079(附属図書館) / 学位論文||R2||N5246(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 山下 洋, 教授 朝倉 彰, 准教授 益田 玲爾 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Using a hydrodynamical smoothed particle hydrodynamics (SPH) zoom-in simu lation of a galaxy group, we present a set of tail identification methods, and study the statistical properties of galaxy tails and their correlations with their expected formation mechanisms. We have a sample of 4548 M > 108 M⊙ galaxies across 58 snapshots from z = 0.67 to z = 0. For each galaxy, we apply a series of velocity and density cuts to identify the tail. We observed no significant correlations between galaxy tail mass and ram pressure, though we note some issues with our sampling. Tracking four visually identified jellyfish galaxies over time showed some evidence of increased ram pressure driving ISM mass loss, as well as spikes in tail mass pre ceding spikes in ram pressure with temporal offsets ranging from 500 Myr to 2 Gyr. No correlation was found between ISM mass and tail mass. We track the tail gas of a particularly well defined jellyfish galaxy 3.2 Gyrs back in time. We find that a lower bound of 30% of the tail gas was never in the ISM. Distinguishing between former ISM tail material and never ISM-accreted tail material, we see evidence of temperature mixing with the IGM in the former. Velocity and radial trajectory maps show a sharp impulse of ∆v ≈ 50 km s−1 over 4 snapshots, affecting both the never ISM-accreted tail material and CGM material, with the former showing evidence of momentum mixing onto the former ISM material. Combined with ob servations of CGM stripping, we propose that a significant portion of galaxy tails consists of stripped CGM that got swept up into the stripped ISM / Thesis / Master of Science (MSc)

Programa LIFE Comisión Europea (LIFE NAT 080064 CUBOMED; Ministerio de Agricultura, Alimentación y Medio Ambiente; Fundación Biodiversidad; Dirección General del Agua, Generalitat Valenciana; Fundació Baleària; El Portet de Denia.

Coastal marine ecosystems are among the most impacted globally, attributable to individual and cumulative effects of human disturbance. Anthropogenic nutrient loading is one stressor that commonly affects nearshore ecosystems, including seagrass beds, and has positive and negative effects on the structure and function of coastal systems. An additional, previously unexplored mechanistic pathway through which nutrients may indirectly influence nearshore systems is by driving blooms of benthic jellyfish. My dissertation research, conducted on Abaco Island, Bahamas, focused on elucidating the role that benthic jellyfish have in structuring systems in which they are common (i.e., seagrass beds), and explored mechanistic processes that may drive blooms of this taxa. To establish that human disturbances (e.g., elevated nutrient availability) may drive increased abundance and size of benthic jellyfish, Cassiopea spp., I conducted surveys in human-impacted and unimpacted coastal sites. Jellyfish were more abundant (and larger) from human-impacted areas, positively correlated to elevated nutrient availability. In order to elucidate mechanisms linking Cassiopea spp. with elevated nutrients, I evaluated whether zooxanthellae from Cassiopea were higher from human-disturbed systems, and whether Cassiopea exhibited increased size following nutrient input. I demonstrated that zooxanthellae population densities were elevated in human-impacted sites, and that nutrients led to positive jellyfish growth. As heightened densities of Cassiopea jellyfish may exert top-down and bottom-up controls on flora and fauna in impacted seagrass beds, I sought to examine ecological responses to Cassiopea. I evaluated whether there was a relationship between high Cassiopea densities and lower benthic fauna abundance and diversity in shallow seagrass beds. I found that Cassiopea have subtle effects on benthic fauna. However, through an experiment conducted in a seagrass bed in which nutrients and Cassiopea were added, I demonstrated that Cassiopea can result in seagrass habitat modification, with negative consequences for benthic fauna. My dissertation research demonstrates that increased human-driven benthic jellyfish densities may have indirect and direct effects on flora and fauna of coastal marine systems. This knowledge will advance our understanding of how human disturbances shift species interactions in coastal ecosystems, and will be critical for effective management of jellyfish blooms.

This diploma thesis deals with the topic of phylum cnidaria as it is being taught in biology classes at primary schools and grammar schools. This work is divided into three parts. The first part deals the position of the topic of phylum cnidaria among curricular documents. It states its classification in the Czech Framework education programme (for Elementary Education) and some chosen School Education Programme. Furthermore, this part analyses the topic as it is written in biology class books, with the clause by the Ministry of Education, Youth and Sports of the Czech Republic. Representatives of phylum cnidaria that are mentioned in biology class books are characterised more thoroughly within the scope of the analysis. The second part of the thesis deals with the teaching methods and forms that are used in teaching biology the most frequently and the questionnaire research that tells us which forms and methods are being used the most by teachers to teach about phylum cnidaria and what specific activities they employ in class. The last part of the thesis consists of suggestions for practical activities for teaching the topic of phylum cnidarian inspired by the results of the survey and a description of educational excursion to the World of Jellyfish aquarium with 6th grade pupils. KEYWORDS phylum...

Ce travail a été entrepris dans le but de caractériser biochimiquement et biologiquement les collagènes de méduse. l’objectif de notre travail a été d’évaluer ce matériel en vue de sa valorisation pour l’élaboration de biomatériaux à usage médical. dans un premier temps, nous avons optimisé les techniques d’extractions des collagènes de quatre espèces de méduses : rhizostoma pulmo, cotylorhiza tuberculata, pelagia noctiluca et aurelia aurita. l’étude de la stabilité thermique par dichroïsme circulaire des collagènes nous a montré que la température de dénaturation des collagènes de rhizostoma pulmo était de 28,9°c. nous avons choisi de réaliser la réticulation des collagènes de méduse par la méthode des carbodiimides (edc/nhs). cette méthode nous a permis d’augmenter la température de dénaturation jusqu’à 33°c (versus 28,9°c). l’étude de l’interaction entre les cellules d’origine humaine (mg63 et fibroblastes) et les collagènes de méduses, nous a permis de démontrer qu’elles étaient capables d’adhérer aux collagènes de méduses natifs ou dénaturés. des immunomarquages de la vinculine des cellules mg63 et des fibroblastes sur collagènes de méduse natifs ou dénaturés nous ont permis de caractériser les adhésions mises en places par ces deux types cellulaires. l’analyse des milieux de culture des cellules mg63 et des fibroblastes par zymographie sur collagènes de méduse natifs ou dénaturés nous a permis de mettre en évidence que des mmps d’origine humaine, seraient capables de dégrader les collagènes de méduses. nous pouvons dans ce cas estimer que le collagène de méduse serait un bon substrat pour l’élaboration de biomatériaux résorbables / This work was undertaken to characterize biochemically and biologically jellyfish collagen. the aim of our study was to evaluate the material for the development of biomaterials for medical use. initially, we optimized the technical extraction of collagen from four species of jellyfishes: rhizostoma pulmo, cotylorhiza tuberculata, pelagia noctiluca and aurelia aurita. the study of thermal stability by circular dichroism of collagen has shown that the denaturation temperature of rhizostoma pulmo collagens was 28.9 ° c. we chose to achieve crosslinking of collagen of jellyfish by the method of carbodiimides (edc/nhs). this method allowed us to increase the denaturation temperature to 33 ° c (vs. 28.9 ° c). the study of the interaction between human cells (mg63 and fibroblasts) and jellyfish collagen, demonstrated that they were able to adhere native or denatured jellyfish collagen. the immunostains of vinculin of mg63 cells and fibroblasts seeded on native or denatured jellyfish collagen, allowed us to characterize the focal adhesions of these two cell types. analysis of culture media of mg63 cells and fibroblasts by collagen zymography on native or denatured jellyfish collagen gels, allowed us to demonstrate that mmps of human origin, are able to degrade jellyfish collagen. we estimate in this case that the jellyfish collagen is a good substrate for the development of resorbable biomaterials