Coral resistance to natural and anthropogenic disturbances

The effects of natural (upwelling, tsunami) and human induced (eutrophication, overfishing, bomb fishing) disturbances to corals were investigated in highly diverse reefs of SE Asia. Firstly, coral recruitment patterns and their contribution to reef recovery and secondly, the corals metabolic flexibility in various environments were investigated. In addition, the bacterial community structure in biofilms was assessed in relation to environmental changes. In summary, the investigated coral reefs seem to be very dynamic visible in recruitment patterns and bacterial community structure being highly responsive to seasonal changes and being able to support reef recovery in most cases. The widely distributed coral species P. lutea and S. subseriata feature a highly flexible metabolism allowing their distribution even to environmental extremes. However, these corals belong to the minority as indicated by the loss of coral diversity in strongly polluted reefs, but it also shows a high interspecific variability, which provides high diversity reefs with a certain buffer capacity to environmental changes

Effects of Eutrophication, Seasonality and Macrofouling on the Diversity of Bacterial Biofilms in Equatorial Coral Reefs

Biofilms play an important role as a settlement cue for invertebrate larvae and significantly contribute to the nutrient turnover in aquatic ecosystems. Nevertheless, little is known about how biofilm community structure generally responds to environmental changes. This study aimed to identify patterns of bacterial dynamics in coral reef biofilms in response to associated macrofouling community structure, microhabitat (exposed vs. sheltered), seasonality, and eutrophication. Settlement tiles were deployed at four reefs along a cross-shelf eutrophication gradient and were exchanged every 4 months over 20 months. The fouling community composition on the tiles was recorded and the bacterial community structure was assessed with the community fingerprinting technique Automated Ribosomal Intergenic Spacer Analysis (ARISA). Bacterial operational taxonomic unit (OTU) number was higher on exposed tiles, where the fouling community was homogenous and algae-dominated, than in sheltered habitats, which were occupied by a variety of filter feeders. Furthermore, OTU number was also highest in eutrophied near-shore reefs, while seasonal variations in community structure were most pronounced in the oligotrophic mid-shelf reef. In contrast, the macrofouling community structure did not change significantly with seasons. Changes in bacterial community patterns were mostly affected by microhabitat, seasonal and anthropogenically derived changes in nutrient availability, and to a lesser extent by changes in the macrofouling community structure. Path analysis revealed a complex interplay of various environmental and biological factors explaining the spatial and temporal variations in bacterial biofilm communities under natural conditions

Calcification, photosynthesis and nutritional status of the hermatypic coral Porites lutea: contrasting case studies from Indonesia and Thailand

In situ incubation experiments, complemented by tissue analyses, were conducted with the coral Porites lutea at four sites featuring contrasting environmental conditions: two shallow (3m) reefs in Spermonde Archi-pelago (Indonesia) subjected to coastal pollution (Lae Lae, LL) and oligotrophic waters (Bonebatang, BBA), respectively; a deep (20m, KR-D) and a shallow (7m, KR-S) reef at off-shore Ko Racha (KR) in the Andaman Sea (Thailand) subjected to pulsed upwelling. Mean tem-perature varied only little (29-30°C). While most tis-sue parameters responded to light and nutrient changes as ex-pected, metabolic rates revealed surprising patterns: 3-fold elevated calcification occurred at KR-S compared to all other sites despite reduced gross photosynthesis. Fur-ther-more, equal photosynthesis occurred in 7 and 20m depth at KR, despite a 5-fold reduction in light intensity, which could not be solely ascribed to photo-acclimation processes, such as increased cell-specific chlorophyll a in 20m depth. These findings support the notion of a highly flexible species and indicate that this might partly be ascribed to a strong variation in the internal turnover of oxygen and nutrients between coral host and zooxanthellae, meaning a strong variation in the rates of energy ac-quisition. Those differences are particularly difficult to determine in situ, but require greater attention in the future in order to enhance our understanding of metabolic pro-cesses and acclimatization abilities

On the signal contribution function with respect to different norms

The signal contribution function (SCF) in multivariate curve resolution evaluates signal portions of specific components either in absolute or in relative form related to the integrated signal of all components. In 1999, Gemperline used the summed signal data, and in 2001, Tauler worked with the square-summed relative signal in order to determine the profiles that minimize, respectively maximize, the signal contribution. These profiles approximate the bands of all feasible profiles. Here, Gemperline's approach using the entrywise 1-matrix norm is proved to provide accurate bounds for two-component systems. This revives the approach of summed mass or absorption values with its potentially better chemical interpretability.Fil: Neymeyr, Klaus. Universität Rostock; Alemania. Leibniz-Institut für Katalyse; AlemaniaFil: Sawall, Mathias. Universität Rostock; AlemaniaFil: Olivieri, Alejandro Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Analítica; Argentin

Discrete Pulses of Cooler Deep Water Can Decelerate Coral Bleaching During Thermal Stress: Implications for Artificial Upwelling During Heat Stress Events

Global warming is considered to be the most severe threat to coral reefs globally, which makes it important for scientists to develop novel strategies that mitigate the impact of warming on corals and associated habitats. Artificial upwelling of cooler deep water to the surface layer may be a possible mitigation/management tool. In this study, we investigated the effect of simulated artificial upwelling with deep water off Bermuda collected at 50 m (24°C) and 100 m (20°C) on coral symbiont biology of 3 coral species (Montastrea cavernosa, Porites astreoides, and Pseudodiploria strigosa) in a temperature stress experiment. The following treatments were applied over a period of 3 weeks: (i) control at 28°C (ii) heat at 31°C, (iii) heat at 31°C+ deep water from 50 m depth, and (iv) heat at 31°C+ deep water from 100 m depth. Artificial upwelling was simulated over a period of 25 min on a daily basis resulting in a reduction of temperature for 2 h per day and the following degree-heating-weeks: 5.7°C-weeks for ii, 4.6°C-weeks for iii and 4.2°C-weeks for iv. Comparative analysis of photosynthetic rate, chlorophyll-a concentration and zooxanthellae density revealed a reduction of heat stress responses in artificial upwelling treatments in 2 of the 3 investigated species, and a stronger positive effect of 100-m water than 50-m water. These results indicate that artificial upwelling could be an effective strategy to mitigate coral bleaching during heat stress events allowing corals to adjust to increasing temperatures more gradually. It will still be necessary to further explore the ecological benefits as well as potential ecosystem impacts associated with different artificial upwelling scenarios to carefully implement an effective in situ artificial upwelling strategy in coral reefs

Charakterisierung von 3 Tiermodellen zur Erzeugung einer interstitiellen Fibrose der Rattenniere und therapeutische Beeinflussung der uranylnitratbedingten Nierenfibrose

Zur Erzeugung einer interstitiellen Nierenfibrose bei Wistarratten wurde drei Tiermodelle (temporäre warme Ischämie, 5/6 Nephrektomie und einmalige Applikation von 0,3 bzw. 0,5mg Uranylnitrat/100g KG i.p) verglichen. Lediglich nach 0,5mg UN/100g KG konnte histologisch eine interstitielle Nierenfibrose nachgewiesen werden. An diesem Modell wurden Ag 1295 (PDGF-Antagonist) und Halofuginone (Kollagen-Typ-I-Synthesehemmer) zur therapeutischen Beeinflussung einer interstitiellen Nierenfibrose untersucht. Ag 1295 erwies sich als nephrotoxisch. Halofuginone war zur Vermeidung der Enstehung einer chronischen Nierenfibrose gut geeignet

Spatio-Temporal Analyses of Symbiodinium Physiology of the Coral Pocillopora verrucosa along Large-Scale Nutrient and Temperature Gradients in the Red Sea

Algal symbionts (zooxanthellae, genus Symbiodinium) of scleractinian corals respond strongly to temperature, nutrient and light changes. These factors vary greatly along the north-south gradient in the Red Sea and include conditions, which are outside of those typically considered optimal for coral growth. Nevertheless, coral communities thrive throughout the Red Sea, suggesting that zooxanthellae have successfully acclimatized or adapted to the harsh conditions they experience particularly in the south (high temperatures and high nutrient supply). As such, the Red Sea is a region, which may help to better understand how zooxanthellae and their coral hosts successfully acclimatize or adapt to environmental change (e.g. increased temperatures and localized eutrophication). To gain further insight into the physiology of coral symbionts in the Red Sea, we examined the abundance of dominant Symbiodinium types associated with the coral Pocillopora verrucosa, and measured Symbiodinium physiological characteristics (i.e. photosynthetic processes, cell density, pigmentation, and protein composition) along the latitudinal gradient of the Red Sea in summer and winter. Despite the strong environmental gradients from north to south, our results demonstrate that Symbiodinium microadriaticum (type A1) was the predominant species in P. verrucosa along the latitudinal gradient. Furthermore, measured physiological characteristics were found to vary more with prevailing seasonal environmental conditions than with region-specific differences, although the measured environmental parameters displayed much higher spatial than temporal variability. We conclude that our findings might present the result of long-term acclimatization or adaptation of S. microadriaticum to regionally specific conditions within the Red Sea. Of additional note, high nutrients in the South correlated with high zooxanthellae density indicating a compensation for a temperature-driven loss of photosynthetic performance, which may prove promising for the resilience of these corals under increase of temperature increase and eutrophication