Browsing by Issue Date, starting with "2024-10-24"
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- Shifts in sulphur-cycling bacteria in the rhizobiome support the adaptation of Caulerpa prolifera to elevated sulphide levelsPublication . Barilo, Anastasiia; Engelen, Aschwin; Wilken, Susanne; Bouwmeester, Harro; Muyzer, GerardCaulerpa is a genus of green macroalgae that lives in tropical and subtropical coastal waters. It is an intriguing organism because, despite having plant-like structures, it is one giant cell – which, next to multiple nuclei, chloroplasts, and mitochondria, also contains endo- and epiphytic bacteria. The role of these bacteria is unknown, but they might impact the growth and development of the host, adaptation to environmental parameters, and, hence, the ecological success of these algae. We hypothesised that increased sulphide concentrations would trigger a significant shift in the microbial community composition associated with C. prolifera rhizoids, favouring sulphide-oxidizing bacteria. To test this hypothesis, we conducted a mesocosm experiment incubating C. prolifera in sediments with different sulphide concentrations and analysed the algal photosynthesis, growth, and microbiome composition. While photosynthesis was not affected, the Caulerpa weight-based growth rate decreased linearly with increasing sulphide concentration. To analyse the microbiome, we extracted DNA and RNA from the fronds, rhizoids, and the accompanying sediments and performed 16S amplicon sequencing. The microbiome of the fronds was unaffected in both the DNA and RNA samples. However, an increase in sulphide concentration coincided with a decrease in the relative abundance of sulphate-reducing bacteria associated with Caulerpa rhizoids, particularly from the family Desulfocapsaceae. In the RNA samples, potential sulphide oxidisers of the rhizoid-associated members of the Beggiatoaceae were detected. Our results suggest that the rhizobiome of Caulerpa plays a significant role in its adaptation to sulphide-rich environments, offering new insights into the complex interactions within marine holobionts.
- An update on the genus Ischiomysis with a description of I. proincisa sp. nov. (Crustacea, Mysida) from a sublittoral marine cave in the Gulf of Guinea (tropical E-Atlantic)Publication . Wittmann, Karl J.; Wirtz, PeterIschiomysis proincisa sp. nov. is described from a comparatively large, semi-dark marine cave in sublittoral waters off the small island Ilhéu das Rolas, directly south of São Tomé Island in the Gulf of Guinea. As striking features, the new species is distinguished from both its congeners by an anteriorly incised rostrum in both sexes and by two versus only one modified flagellate spine on the ischium of the eighth thoracic endopod in males. The new species is sympatric yet ecologically remote from the congener I. telmatactiphila, which is associated with the sea anemone Telmatactis cricoides in brighter habitats. New records and morphological notes are given for I. telmatactiphila and I. peterwirtzi. An updated definition of the genus Ischiomysis and a key to its three species are given.
- Phosphorous loads in the heilsau catchment spatial distribution and temporal variationPublication . Jann, Valentin Elias; Chícharo, Luís; Wellbrock, KaiEutrophication of aquatic ecosystems is a global environmental issue. Mostly caused by excessive inputs of nutrients such as phosphorous and nitrogen, a catchment-wide understanding of nutrient and sediment pathways and their drivers is necessary. This thesis focuses on the assessment of phosphorus (P) inputs in the Heilsau Catchment, aiming to better understand its impact on eutrophication. Utilising both historical data and own field measurements, this study examines various sources of phosphorus and their contributions to the total phosphorus load in the catchment. The study area was characterised by its hydrological, topographical, and land use features, with an assessment of soil, watercourses, and anthropogenic modifications. Discharge and precipitation data were integrated with instream water quality measurements to track the temporal variation and potential drivers of phosphorus loads. Furthermore, the concentration-discharge (C-Q) relationship was analysed, and a model was built for estimating P concentrations through baseflow and direct runoff contribution. Sampling of tributaries, sewage effluents, and drainage systems provided additional data on the spatial distribution of phosphorus from point and diffuse sources. Results indicate that the majority of phosphorous reaches the waterbodies through erosion, sewage effluents, and drainage. The analysis on a subcatchment level enabled to identify hotspot areas and hence interpret consequences for an improved catchment management. Measures should include the retention of sediments and dissolved phosphorous from erosion-prone areas, and the enhancement of P-removal in sewage treatment. This study contributes to the ongoing efforts of improving the water quality and secure ecosystem services in the Heilsau catchment, offering actionable insights for environmental management.
- Patrimônio e comunidade: ruínas romanas de Milreu, Estoi (Faro)Publication . Jácomo, Fernando Rodrigues de; Bernardes, João PedroMilreu é um importante sítio arqueológico localizado a 7 km de Faro, na aldeia de Estoi, Portugal. Inclui uma variedade de estruturas romanas que reconta um período ocupacional milenar. No entanto, tamanha relevância não impediu que houvesse um distanciamento com sua comunidade local que se coloca pouco engajada com relação ao espaço apesar desta estar inserida em uma aldeia com elementos históricos e culturais ricos. Este projeto visou analisar a relação atual entre Milreu e a comunidade de Estoi e compreender as razões para esse distanciamento. Por meio da aplicação de inquéritos online e entrevistas individuais, foi proposta uma discussão pautada nas diretrizes da arqueologia comunitária para compreender as principais divergências e expectativas entre população e agentes responsáveis pelo sítio. Nesse sentido compreender as competências necessárias para um plano de reversão e estabelecer bases para a aplicação de ações concretas corretivas.