Description: Biological and environmental changes are creating a growing demand for historical and global data sets. Comparing up-to-date ecological and biological findings with historical statements has become a major part of scientific work in the field of ecology. This evaluation and comparison procedure is very time-consuming while the availability of raw data is very low. Comparisons between original findings – if available – require a lot of work from print publication to digitalization or transformation to appropriate data formats. The effective use of working capacity is a general issue and has become important, should the use of information technologies be invoked to minimize time-wasting copy and paste operations. In this paper we aim to present a working repository for terrestrial biological data. The implementation of this type of data repository will provide various services to participating scientists as long as the final aim is the publication of these repositories. Furthermore, the security and long-term availability of environmental data is an issue of increasing importance to the scientific community. Unrepeatable sampling events and any data thus obtained are precious in time series analysis. For this reason, a well-structured storage of data is necessary for easy accessibility, retrieval and comparability. This is an important issue for the community of environmental scientists. The need to construct and implement repositories should prevail against all hitches and we are therefore describing our on-going task with the primary population of this kind of data repository. A biological and ecological information system is a matter of public interest and should also be a key issue for ecologists.

Description: Phytoplankton and bacteria are sensitive indicators of environmental change. The temporal development of these key organisms was monitored from 1988 to the end of 2007 at the time series station Boknis Eck in the western Baltic Sea. This period was characterized by the adaption of the Baltic Sea ecosystem to changes in the environmental conditions caused by the conversion of the political system in the southern and eastern border states, accompanied by the general effects of global climate change. Measured variables were chlorophyll, primary production, bacteria number, -biomass and -production, glucose turnover rate, macro-nutrients, pH, temperature and salinity. Negative trends with time were recorded for chlorophyll, bacteria number, bacterial biomass and bacterial production, nitrate, ammonia, phosphate, silicate, oxygen and salinity while temperature, pH, and the ratio between bacteria numbers and chlorophyll increased. Strongest reductions with time occurred for the annual maximum values, e.g. for chlorophyll during the spring bloom or for nitrate during winter, while the annual minimum values remained more stable. In deep water above sediment the negative trends of oxygen, nitrate, phosphate and bacterial variables as well as the positive trend of temperature were similar to those in the surface while the trends of salinity, ammonia and silicate were opposite to those in the surface. Decreasing oxygen, even in the surface layer, was of particular interest because it suggested enhanced recycling of nutrients from the deep hypoxic zones to the surface by vertical mixing. The long-term seasonal patterns of all variables correlated positively with temperature, except chlorophyll and salinity. Salinity correlated negatively with all bacterial variables (as well as precipitation) and positively with chlorophyll. Surprisingly, bacterial variables did not correlate with chlorophyll, which may be inherent with the time lag between the peaks of phytoplankton and bacteria during spring. Compared to the 20-yr averages of the environmental and microbial variables, the strongest negative deviations of corresponding annual averages were measured about ten years after political change for nitrate and bacterial secondary production (~ −60%), followed by chlorophyll (−50%) and bacterial biomass (−40%). Considering the circulation of surface currents in the Baltic Sea we interpret the observed patterns of the microbial variables at the Boknis Eck time series station as a consequence of the improved management of water resources after 1989 and – to a minor extent – the trends of the climate variables salinity and temperature.

Description: This paper focuses on the marine foundation eelgrass species, Zostera marina, along a gradient from the northern Baltic Sea to the north-east Atlantic. This vast region supports a minimum of 1480 km2 eelgrass (maximum 〉2100 km2), which corresponds to more than four times the previously quantified area of eelgrass in Western Europe. Eelgrass meadows in the low salinity Baltic Sea support the highest diversity (4–6 spp.) of angiosperms overall, but eelgrass productivity is low (〈2 g dw m-2 d-1) and meadows are isolated and genetically impoverished. Higher salinity areas support monospecific meadows, with higher productivity (3–10 g dw m-2 d-1) and greater genetic connectivity. The salinity gradient further imposes functional differences in biodiversity and food webs, in particular a decline in number, but increase in biomass of mesograzers in the Baltic. Significant declines in eelgrass depth limits and areal cover are documented, particularly in regions experiencing high human pressure. The failure of eelgrass to re-establish itself in affected areas, despite nutrient reductions and improved water quality, signals complex recovery trajectories and calls for much greater conservation effort to protect existing meadows. The knowledge base for Nordic eelgrass meadows is broad and sufficient to establish monitoring objectives across nine national borders. Nevertheless, ensuring awareness of their vulnerability remains challenging. Given the areal extent of Nordic eelgrass systems and the ecosystem services they provide, it is crucial to further develop incentives for protecting them.

Description: Results of the of the present study provide a strong indication that reproductive periods of the bladderwrack Fucus vesiculosus is tuned by environmental conditions, such as day length, although it cannot be entirely ruled out that genetic constitution may play a role, as well. Furthermore results of the present study identified high temperatures as the most challenging condition for alga recruitment. Sea surface temperature rise could therefore be one of the reasons for the decline of F. vesiculosus populations in the Baltic Sea over the last few decades, particularly in the marginal environments (〈 7 psu). Additionally, fertility of F. vesiculosus from the marginal region, in contrast to all other regions, was very low, which also indicates towards a lower capacity to deal with environmental changes. A rather high germination success of some sibling groups (F. vesiculosus) under various environmental conditions, however, is promising in the light of adaptation to climate change.

Description: Small to meso-scale distribution of Baltic cod (Gadus morhua L.) as resolved by hydroacoustics: Habitat preferences, environmental limits, and resulting implications for stock development

Description: The accumulation of gas hydrates in marine sediments is essentially controlled by the accumulation of particulate organic carbon (POC) which is microbially converted into methane, the thickness of the gas hydrate stability zone (GHSZ) where methane can be trapped, the sedimentation rate (SR) that controls the time that POC and the generated methane stays within the GHSZ, and the delivery of methane from deep-seated sediments by ascending pore fluids and gas into the GHSZ. Recently, Wallmann et al. (2012) presented transfer functions to predict the gas hydrate inventory in diffusion-controlled geological systems based on SR, POC and GHSZ thickness for two different scenarios: normal and full compacting sediments. We apply these functions to global data sets of bathymetry, heat flow, seafloor temperature, POC input and SR, estimating a global mass of carbon stored in marine methane hydrates from 3 to 455 Gt of carbon (GtC) depending on the sedimentation and compaction conditions. The global sediment volume of the GHSZ in continental margins is estimated to be 60–67 × 1015 m3, with a total of 7 × 1015 m3 of pore volume (available for GH accumulation). However, seepage of methane-rich fluids is known to have a pronounced effect on gas hydrate accumulation. Therefore, we carried out a set of systematic model runs with the transport-reaction code in order to derive an extended transfer function explicitly considering upward fluid advection. Using averaged fluid velocities for active margins, which were derived from mass balance considerations, this extended transfer function predicts the enhanced gas hydrate accumulation along the continental margins worldwide. Different scenarios were investigated resulting in a global mass of sub-seafloor gas hydrates of ~ 550 GtC. Overall, our systematic approach allows to clearly and quantitatively distinguish between the effect of biogenic methane generation from POC and fluid advection on the accumulation of gas hydrate, and hence, provides a simple prognostic tool for the estimation of large-scale and global gas hydrate inventories in marine sediments.

Description: Seagrass is a foundation species within shallow water ecosystems because it provides habitat and food and thereby supports biodiversity. It has a function as atmospheric CO2 storage and improves the water quality by filtering nutrients (Greiner et al. 2013). Currently, seagrass meadows are facing multiple challenges such as ocean warming, reduced light caused by increasing nutrient input and more frequent disturbance events or direct anthropogenic impact (Unsworth et al. 2019). All these factors affect the performance of seagrass and thereby impair the ecosystem services seagrass meadows provide. This thesis represents a systematic review and meta-analysis of the physiological effects of temperature change on seagrass to provide a better understanding of the effect of rising temperatures on seagrass meadows worldwide. In this thesis, 766 papers were reviewed and a subsequent meta-analysis of 43 papers including 407 control-treatment temperature combinations matching the inclusion criteria were conducted. The log response ratio (lnR) was used for calculating the effect sizes, because it is more intuitive to interpret. Hedges’ g was further used to verify the results. It was tested for effects of the physiological parameters measured, the treatment type, the temperature direction, the experiment duration, the control temperature, latitude and longitude of the source population and the genus on relative seagrass performance (lnR). The key results of the meta-analysis showed that (I) plant physiological performance was reduced by an average of 39% by temperature change across all studies; (II) per 1°C experimental ocean warming a reduction in seagrass performance of 11% was observed; (III) the measured performance parameters (growth, biomass, photosynthesis and survival) showed differential susceptibility to warming, with survival being most affected and photosynthesis least affected; (IV) seagrass genera did not differ significantly in their response to experimental ocean warming but varied between locations. There was a strong geographic bias in this meta-analysis since most case studies were conducted in developed countries including Europe, the US and Australia. Thus, many species were underrepresented while also some climate conditions were not covered. Further, it was also not possible to make a statement about the recovery after experimental temperature stress had ceased, as there were too few studies focusing on recovery. Altogether, this thesis identified two profound knowledge gaps, which should be addressed by future studies. In conclusion, more frequent and intense heat waves are an increasing threat to seagrass meadows in the future. As seagrass provides important ecological services, it needs to be protected. It is particularly striking that every degree Celsius of temperature change matters for seagrass as it means a reduction in physiological and morphological performance, which is another indication that global warming should be kept below 2 degrees Celsius

Description: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil-fuel combustion and cement production (EFF) are based on energy statistics, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated for the first time in this budget with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2 and land cover change (some including nitrogen–carbon interactions). All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2003–2012), EFF was 8.6 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.5 ± 0.5 GtC yr−1, and SLAND 2.8 ± 0.8 GtC yr−1. For year 2012 alone, EFF grew to 9.7 ± 0.5 GtC yr−1, 2.2% above 2011, reflecting a continued growing trend in these emissions, GATM was 5.1 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and assuming an ELUC of 1.0 ± 0.5 GtC yr−1 (based on the 2001–2010 average), SLAND was 2.7 ± 0.9 GtC yr−1. GATM was high in 2012 compared to the 2003–2012 average, almost entirely reflecting the high EFF. The global atmospheric CO2 concentration reached 392.52 ± 0.10 ppm averaged over 2012. We estimate that EFF will increase by 2.1% (1.1–3.1%) to 9.9 ± 0.5 GtC in 2013, 61% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the economy. With this projection, cumulative emissions of CO2 will reach about 535 ± 55 GtC for 1870–2013, about 70% from EFF (390 ± 20 GtC) and 30% from ELUC (145 ± 50 GtC). This paper also documents any changes in the methods and data sets used in this new carbon budget from previous budgets (Le Quéré et al., 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2013_V2.3).

Description: A central question in ecology is how organisms react to changing environmental conditions induced by global climate change. This is particularly important for ecosystem engineering species, as the fate of whole ecosystems is depending upon their performance and survival. In coastal marine habitats, seagrasses are of outstanding importance as ecosystem builders. Eelgrass, the study species of this thesis, is the most widespread and locally abundant seagrass along soft-sediment coasts of the northern hemisphere. In this thesis I assessed variation among and within eelgrass populations in response to heat stress. I conducted heat stress experiments in a “common stress garden”, simulating a summer heat wave of three weeks followed by a recovery phase. I measured various physiological parameters and assessed the expression profile of selected heat stress associated genes with qPCR as well as the whole transcriptome with next generation sequencing using eelgrass with differing thermal history (a southern population from the Mediterranean Sea and northern populations from the Kattegat and Limfjord, Baltic Sea). To assess variation within populations, I used genotypes originating from a Baltic population. I found that different genotypes showed varying growth rates in control and heat treatment at acute heat stress, but that all populations lost shoots in response to the heat wave, irrespective of their thermal pre-adaptation. While populations diverged in their expression profiles of selected heat stress associated genes already at the onset of heat stress, subsequent global transcription profiling revealed that those effects were of relatively minor importance compared to massive differences in gene expression during the recovery phase between two of the populations. This is in line with findings on the genotype level within one population which showed differences in the expression profiles of selected stress-associated genes between replicated individuals only in the recovery phase. This thesis provides a basis for investigating the potential for microevolution of eelgrass populations in the face of global climate change. Both, cold- as well as warm adapted eelgrass populations responded to heat stress with shoot reduction, a finding that is in line with worldwide records of seagrass decline. On the other hand, there is considerable variation for heat stress-related gene expression within populations, a trait that is likely to be important under global change. As this variation among genotypes is the prerequisite for natural selection and adaptation, populations may succeed to persist.