Description: There is significant commercial and research interest in the application of sea cucumbers as nutrient recyclers and processors of particulate waste in polyculture or integrated multitrophic aquaculture (IMTA) systems. The following article reviews examples of existing IMTA systems operating with sea cucumbers, and details the role and effect of several sea cucumber species in experimental and pilot IMTA systems worldwide. Historical observations and quantification of impacts of sea cucumber deposit-feeding and locomotion are examined, as is the development and testing of concepts for the application of sea cucumbers in sediment remediation and site recovery. The extension of applied IMTA systems is reported, from basic piloting through to economically viable farming systems operating at commercial scales. The near-global recognition of the ecological and economic value of deposit-feeding sea cucumbers in IMTA applications within existing and developing aquaculture industries is discussed. Predictions and recommendations are offered for optimal development of sea cucumber IMTA globally. Future directions within the industry are indicated, and key areas of ecological, biological and commercial concern are highlighted to be kept in mind and addressed in a precautionary manner as the industry develops.

Description: Gambierdiscus, a benthic dinoflagellate, produces ciguatoxins that cause the human illness Ciguatera. Ciguatoxins are polyether ladder compounds that have a polyketide origin, indicating that polyketide synthases (PKS) are involved in their production. We sequenced transcriptomes of Gambierdiscus excentricus and Gambierdiscus polynesiensis and found 264 contigs encoding single domain ketoacyl synthases (KS; G. excentricus: 106, G. polynesiensis: 143) and ketoreductases (KR; G. excentricus: 7, G. polynesiensis: 8) with sequence similarity to type I PKSs, as reported in other dinoflagellates. In addition, 24 contigs (G. excentricus: 3, G. polynesiensis: 21) encoding multiple PKS domains (forming typical type I PKSs modules) were found. The proposed structure produced by one of these megasynthases resembles a partial carbon backbone of a polyether ladder compound. Seventeen contigs encoding single domain KS, KR, s-malonyltransacylase, dehydratase and enoyl reductase with sequence similarity to type II fatty acid synthases (FAS) in plants were found. Type I PKS and type II FAS genes were distinguished based on the arrangement of domains on the contigs and their sequence similarity and phylogenetic clustering with known PKS/FAS genes in other organisms. This differentiation of PKS and FAS pathways in Gambierdiscus is important, as it will facilitate approaches to investigating toxin biosynthesis pathways in dinoflagellates.

Description: The Global Geodetic Reference Frame (GGRF) plays a fundamental role in geodesy and related Positioning, Navigation, and Timing applications, and allows to quantify the Earth’s change in space and time. The ITRF and ICRF are the two most important components to realize GGRF, while the determination of these two reference frames relies on the combination of several space geodetic techniques, mainly, VLBI, SLR, GNSS, and DORIS. The combination is currently done on either the parameter level, or the normal equation level. However, the combination on the observation level, or the so-called integrated processing of multi-technique on the observation level, provides the results of best consistency, robustness, and accuracy. This thesis focuses on the investigation of the integrated processing of GNSS and VLBI on the observation level. The benefits of integrated processing are demonstrated in terms of TRF, CRF, and EOP, while the impact of global ties (EOP), tropospheric ties, and local ties are underlined. Several issues in integrated processing are addressed, including the systematic bias in ties (for instance, LOD and tropospheric ties), the relative weighting. An automatic reweighting strategy based on the normalized residuals is developed, which can properly handle the uncertainty of the ties without losing too much constraint. A software with state-of-the-art modules is the prerequisite to perform integrated processing. Based on the GNSS data processing software: Positioning And Navigation Data Analyst (PANDA), the VLBI and SLR modules are implemented in the common least-squares estimator. Therefore, the best consistency can be guaranteed. The software capability is demonstrated with the single-technique solutions. The station coordinate precision is at millimeter level for both GNSS and VLBI, while the EOP estimates are comparable to other Analysis Centers and the IERS products. It is also demonstrated that the SLR station coordinate precision is improved by 20% to 30% with additional GLONASS and GRACE satellites to contributing to the LAGEOS and ETALON constellation. Focusing on the tropospheric ties in GNSS and VLBI integrated processing, its contribution is demonstrated for the first time comprehensively. Applying tropospheric ties improves the VLBI station coordinate precision by 12% on the horizontal components and up to 30% on the vertical component. The network scale repeatability is reduced by up to 33%. The EOP estimates are also improved significantly, for instance, 10% to 30% for polar motion, and up to 10% for other components. Furthermore, applying the gradient ties in the VLBI intensive sessions reduces the systematic bias in UT1-UTC estimates. The consistent TRF, CRF, and EOP are achieved in the integrated VLBI and GNSS solution. Applying the global ties, tropospheric ties, and local ties stables the reference frame. The ERP estimates in the integrated solution are dominated by the GNSS technique, and the VLBI technique introduces additional 10% improvement on the y-pole component in terms of the day-boundary-discontinuity. The UT1-UTC and celestial pole offsets are also slightly improved in the integrated solution. It is also demonstrated that applying the LTs inappropriately distorts the network and introduces systematic biases to the ERP estimates, addressing the necessity of updating the local surveys. Moreover, the coordinates of AGN are also enhanced by up to 20% in the integrated solutions, especially the southern ones. This study reveals the importance of integrated processing of multi-technique on the observation level, as the best consistency can be achieved, and the applied ties improve the solutions significantly. It is strongly recommended that for the future realization of celestial and terrestrial reference frames, the concept of integrated processing on the observation level should be implemented, and all the possible ties should be applied, including the global ties (EOP), local ties, space ties, and tropospheric ties. Such kind of integrated solution of all the four techniques can provide robust estimates of the reference frames and EOP, with the advantage of each technique exploited to its full extend.

Description: Der Globale Geodätische Referenzrahmen (Global Geodetic Reference Frame, GGRF) spielt eine fundamentale Rolle in der Geodäsie und den damit verbundenen Positionierungs-, Navigations- und Zeitmessungsanwendungen (Positioning, Navigation, and Timing, PNT) und ermöglicht die Quantifizierung der Veränderung der Erde in Raum und Zeit. Der ITRF und der ICRF sind die beiden wichtigsten Komponenten zur Realisierung des GGRF, wobei die Bestimmung dieser beiden Referenzrahmen auf der Kombination verschiedener raumgeodätischer Techniken beruht, hauptsächlich VLBI, SLR, GNSS und DORIS. Die Kombination wird derzeit entweder auf der Parameterebene oder auf der Normalgleichungsebene durchgeführt. Die Kombination auf der Beobachtungsebene oder die sogenannte integrierte Daten-Verarbeitung von Multi-Techniken auf der Beobachtungsebene, bietet jedoch eine Lösung mit der besten Konsistenz, Robustheit und Genauigkeit. Diese Arbeit konzentriert sich auf die Untersuchung der integrierten Daten-Verarbeitung von GNSS und VLBI auf der Beobachtungsebene. Die Vorteile der integrierten Lösung werden in Bezug auf TRF, CRF, und EOP aufgezeigt, während die Auswirkungen von „Global Ties (EOP), Tropospheric Ties, and Local Ties“ hervorgehoben werden. Einige Punkte der integrierten Verarbeitung werden in dieser Arbeit untersucht, einschließlich der systematischen Abweichungen von „Ties“ (z.B. LOD und Tropospheric Ties), der relativen Gewichtung usw. Anhand der normalisierten Residuen wird eine automatische Umgewichtungsstrategie entwickelt, mit der die Unsicherheit der „Ties“ angemessen behandelt werden kann, ohne dass zu viel Einschränkung dabei verloren geht. Eine Software mit modernsten Modulen ist die Voraussetzung für die integrierte Daten Verarbeitung. Basierend auf der GNSS-Datenverarbeitungssoftware Paket: Positioning And Navigation Data Analyst (PANDA) werden die Module VLBI und SLR in demselben Least-Squares-Estimator wie GNSS implementiert, damit kann man die beste Konsistenz in der Datenverarbeitung erreichen. In dieser Arbeit wird die Leistungsfähigkeit der Software mit den Ein-Technik-Lösungen demonstriert. Die Genauigkeit der Stationskoordinaten liegt sowohl für GNSS als auch für VLBI im Millimeterbereich, und die geschätzten EOP-Parameter sind auch mit der anderer Analysezentren und den IERS-Produkten vergleichbar. Es wird auch gezeigt, dass die Koordinatengenauigkeit der SLR-Station um 20-30% verbessert wird, wenn zusätzliche GLONASS- und GRACE-Satelliten zur LAGEOS und ETALON-Konstellation beitragen. Mit dem Schwerpunkt auf den „Tropospheric Ties“ in der integrierten GNSS- und VLBI- Daten Verarbeitung wird ihr Beitrag zum ersten Mal umfassend dargestellt. Die Anwendung der „Tropospheric Ties“ verbessert die Genauigkeit der VLBI-Koordinaten um 12% bei der horizontalen Komponente und bis zu 30% bei der vertikalen Komponente. Die Genauigkeit im Netzwerkmaßstab wird um bis zu 33% verbessert. Auch die EOP-Bestimmungen werden deutlich verbessert, z.B. um 10-30% bei polaren Bewegungen und bis zu 10% bei anderen Komponenten. Darüber hinaus reduziert die Einführung der „Gradient Ties“ in der VLBI-Intensivsession die systematische Abweichung in den dUT1-Bestimmungen. Die konsistente TRF, CRF, und EOP werden bei der integrierten VLBI- und GNSS-Lösung erreicht. Die Anwendung der „Global Ties, Tropospheric Ties and Local Ties“ stabilisiert die Bestimmungen des Referenzrahmens. Die ERP-Bestimmungen in der integrierten Lösung werden von der GNSS-Technik dominiert, und die VLBI-Technik bringt eine zusätzliche Verbesserung um 10% auf die Tagesgrenzen-Diskontinuität (day-boundary-discontinuity, DBD) für die y-Pol-Komponente. Die dUT1- und CPO werden in der integrierten Lösung ebenfalls leicht verbessert. Es wird auch gezeigt, dass eine ungeeignete Anwendung der LTs das Netzwerk verzerrt und systematische Abweichungen in die ERP-Bestimmungen einführt, wodurch die Notwendigkeit einer Aktualisierung der lokalen Tie Messungen deutlich wird. Darüber hinaus werden die Koordinaten der AGN in den integrierten Lösungen um bis zu 20% verbessert, insbesondere im Süden. Diese Arbeit zeigt die Bedeutung der integrierten Daten Verarbeitung von Multi-Technik auf der Beobachtungsebene, da die beste Konsistenz erreicht werden kann und die angewandten „Ties“ die Lösungen erheblich verbessern. Es wird nachdrücklich empfohlen, für die zukünftige Realisierung von himmelsfesten und erdfesten Referenzrahmen das Konzept der integrierten Verarbeitung auf Beobachtungsebene durchzuführen und alle möglichen „Ties“ anzuwenden, einschließlich der „Global Ties (EOP), Local Ties, Space Ties, and Tropospheric Ties“. Eine solche integrierte Lösung aller vier Techniken kann die robusten Bestimmungen der Referenzrahmen und der EOP liefern, wobei die Vorteile jeder Technik voll ausgeschöpft werden.

Description: Large amounts of organic carbon are stored in Arctic permafrost environments, and microbial activity can potentially mineralize this carbon into methane, a potent greenhouse gas. In this study, we assessed the methane budget, the bacterial methane oxidation (MOX) and the underlying environmental controls of arctic lake systems, which represent substantial sources of methane. Five lake systems located on Samoylov Island (Lena Delta, Siberia) and the connected river sites were analyzed using radiotracers to estimate the MOX rates, and molecular biology methods to characterize the abundance and the community composition of methane-oxidizing bacteria (MOB). In contrast to the river, the lake systems had high variation in the methane concentrations, the abundance and composition of the MOB communities, and consequently, the MOX rates. The highest methane concentrations and the highest MOX rates were detected in the lake outlets and in a lake complex in a floodplain area. Though, in all aquatic systems we detected both, Type I and II MOB, in lake systems we observed a higher diversity including MOB, typical of the soil environments. The inoculation of soil MOB into the aquatic systems, resulting from permafrost thawing, might be an additional factor controlling the MOB community composition and potentially methanotrophic capacity.

Description: 1. Plant diversity is an important driver of belowground ecosystem functions, such as root growth, soil organic matter (SOM) storage, and microbial metabolism, mainly by influencing the interactions between plant roots and soil. Dissolved organic matter (DOM), as the most mobile form of SOM, plays a crucial role for a multitude of soil processes that are central for ecosystem functioning. Thus, DOM is likely to be an important mediator of plant diversity effects on soil processes. However, the relationships between plant diversity and DOM have not been studied so far. 2. We investigated the mechanisms underlying plant diversity effects on concentrations of DOM using continuous soil water sampling across 6 years and 62 plant communities in a long‐term grassland biodiversity experiment in Jena, Germany. Furthermore, we investigated plant diversity effects on the molecular properties of DOM in a subset of the samples. 3. Although DOM concentrations were highly variable over the course of the year with highest concentrations in summer and autumn, we found that DOM concentrations consistently increased with plant diversity across seasons. The positive plant diversity effect on DOM concentrations was mainly mediated by increased microbial activity and newly sequestered carbon in topsoil. However, the effect of soil microbial activity on DOM concentrations differed between seasons, indicating DOM consumption in winter and spring, and DOM production in summer and autumn. Furthermore, we found increased contents of small and easily decomposable DOM molecules reaching deeper soil layers with high plant diversity. 4. Synthesis. Our findings suggest that plant diversity enhances the continuous downward transport of DOM in multiple ways. On the one hand, higher plant diversity results in higher DOM concentrations, on the other hand, this DOM is less degraded. The present study indicates, for the first time, that higher plant diversity enhances the downward transport of dissolved molecules that likely stimulate soil development in deeper layers and therefore increase soil fertility.

Description: To understand the adaptation of euphausiid (krill) species to oxygen minimum zones (OMZ), respiratory response and stress experiments combining hypoxia/reoxygenation exposure with warming were conducted. Experimental krill species were obtained from the Antarctic (South Georgia area), the Humboldt Current system (HCS, Chilean coast), and the Northern California Current system (NCCS, Oregon). Euphausia mucronata from the HCS shows oxyconforming pO2-dependent respiration below 80% air saturation (18 kPa). Normoxic subsurface oxygenation in winter posed a “high oxygen stress” for this species. The NCCS krill, Euphausia pacifica, and the Antarctic krill, Euphausia superba maintain respiration rates constant down to low critical pO2 values of 6 kPa (30% air saturation) and 11 kPa (55% air saturation), respectively. Antarctic krill had low antioxidant enzyme activities, but high concentrations of the molecular antioxidant glutathione (GSH) and was not lethally affected by 6 h exposure to moderate hypoxia. Temperate krill species had higher SOD (superoxide dismutase) values in winter than in summer, which relate to higher winter metabolic rate (E. pacifica). In all species, antioxidant enzyme activities remained constant during hypoxic exposure at the typical temperature for their habitat. Warming by 7°C above their typical temperature in summer increased SOD activities and GSH levels in E. mucronata (HCS), but no oxidative damage occurred. In winter, when the NCCS is well mixed and the OMZ is deeper, +4°C of warming combined with hypoxia represents a lethal condition for E. pacifica. In summer, when the OMZ expands upwards (100 m subsurface), antioxidant defences counteracted hypoxia and reoxygenation effects in E. pacifica, but only at mildly elevated temperature (+2°C). In this season, experimental warming by +4°C reduced antioxidant activities and the combination of warming with hypoxia again caused mortality of exposed specimens. We conclude that a climate change scenario combining warming and hypoxia represents a serious threat to E. pacifica and, as a consequence, NCCS food webs.

Description: Understanding cetacean distribution is essential for conservation planning and decision-making, particularly in regions subject to rapid environmental changes. Nevertheless, information on their spatiotemporal distribution is commonly limited, especially from remote areas. Species distribution models (SDMs) are powerful tools, relating species occurrences to environmental variables to predict the species' potential distribution. This study aims at using presence-only SDMs (MaxEnt) to identify suitable habitats for fin whales (Balaenoptera physalus) on their Nordic and Barents Seas feeding grounds. We used spatial-block cross-validation to tune MaxEnt parameters and evaluate model performance using spatially independent testing data. We considered spatial sampling bias correction using four methods. Important environmental variables were distance to shore and sea ice edge, variability of sea surface temperature and sea surface salinity, and depth. Suitable fin whale habitats were predicted along the west coast of Svalbard, between Svalbard and the eastern Norwegian Sea, coastal areas off Iceland and southern East Greenland, and along the Knipovich Ridge to Jan Mayen. Results support that presence-only SDMs are effective tools to predict cetacean habitat suitability, particularly in remote areas like the Arctic Ocean. SDMs constitute a cost-effective method for targeting future surveys and identifying top priority sites for conservation measures.

Description: Global concern about human impact on biological diversity has triggered an intense research agenda on drivers and consequences of biodiversity change in parallel with international policy seeking to conserve biodiversity and associated ecosystem functions. Quantifying the trends in biodiversity is far from trivial, however, as recently documented by meta-analyses, which report little if any net change in local species richness through time. Here, we summarise several limitations of species richness as a metric of biodiversity change and show that the expectation of directional species richness trends under changing conditions is invalid. Instead, we illustrate how a set of species turnover indices provide more information content regarding temporal trends in biodiversity, as they reflect how dominance and identity shift in communities over time. We apply these metrics to three monitoring datasets representing different ecosystem types. In all datasets, nearly complete species turnover occurred, but this was disconnected from any species richness trends. Instead, turnover was strongly influenced by changes in species presence (identities) and dominance (abundances). We further show that these metrics can detect phases of strong compositional shifts in monitoring data and thus identify a different aspect of biodiversity change decoupled from species richness. Synthesis and applications: Temporal trends in species richness are insufficient to capture key changes in biodiversity in changing environments. In fact, reductions in environmental quality can lead to transient increases in species richness if immigration or extinction has different temporal dynamics. Thus, biodiversity monitoring programmes need to go beyond analyses of trends in richness in favour of more meaningful assessments of biodiversity change.

Description: While there is a lot of data on interactive effects of eutrophication and warming, to date, we lack data to generate reliable predictions concerning possible effects of nutrient decrease and temperature increase on community composition and functional responses. In recent years, a wide‐ranging trend of nutrient decrease (re‐oligotrophication) was reported for freshwater systems. Small lakes and ponds, in particular, show rapid responses to anthropogenic pressures and became model systems to investigate single as well as synergistic effects of warming and fertilization in situ and in experiments. Therefore, we set up an experiment to investigate the single as well as the interactive effects of nutrient reduction and gradual temperature increase on a natural freshwater phytoplankton community, using an experimental indoor mesocosm setup. Biomass production initially increased with warming but decreased with nutrient depletion. If nutrient supply was constant, biomass increased further, especially under warming conditions. Under low nutrient supply, we found a sharp transition from initially positive effects of warming to negative effects when resources became scarce. Warming reduced phytoplankton richness and evenness, whereas nutrient reduction at ambient temperature had positive effects on diversity. Our results indicate that temperature effects on freshwater systems will be altered by nutrient availability. These interactive effects of energy increase and resource decrease have major impacts on biodiversity and ecosystem function and thus need to be considered in environmental management plans.

Description: This report describes the activities performed within Task 1.3 “Summary of gas solubility and degassing kinetics (type A)” until the end of month 39 of the REFLECT project. Two series of experiments have been carried out that assess the degassing process of type A geothermal fluids respectively in bulk and porous media. This has resulted in an improved understanding of the process and the associated physical phenomena by utilizing experimental equipment and data analysis tools specifically created for this task.