Feasibility study for co-digestion of sewage sludge with OFMSW on two wastewater treatment plants in Germany

In the past years, wastewater treatment plants (WWTP) in Germany have often been enlarged or expanded. However, it has become evident that the prognosticated increase in wastewater amount has not become a reality and thus free capacities, particularly in the sewage sludge digesters, are available. A possibility for the use of these available capacities is the fermentation of sewage sludge together with organic waste. A feasibility study for two different wastewater treatment plants in Germany was done in order to estimate if fermentation of the organic fraction of municipal solid waste (OFMSW) affects the wastewater treatment plant operation. In this study, the technical, economic and ecological aspects of co-digestion were investigated for the plants selected.     

Modeling eelgrass spatial response to nutrient abatement measures in a changing climate

For many coastal areas including the Baltic Sea, ambitious nutrient abatement goals have been set to curb eutrophication, but benefits of such measures were normally not studied in light of anticipated climate change. To project the likely responses of nutrient abatement on eelgrass (Zostera marina), we coupled a species distribution model with a biogeochemical model, obtaining future water turbidity, and a wave model for predicting the future hydrodynamics in the coastal area. Using this, eelgrass distribution was modeled for different combinations of nutrient scenarios and future wind fields. We are the first to demonstrate that while under a business as usual scenario overall eelgrass area will not recover, nutrient reductions that fulfill the Helsinki Commission’s Baltic Sea Action Plan (BSAP) are likely to lead to a substantial areal expansion of eelgrass coverage, primarily at the current distribution’s lower depth limits, thereby overcompensating losses in shallow areas caused by a stormier climate.     

Different patterns of carotenoid composition and photosynthesis acclimation in two tropical red algae

To be able to survive, marine macroalgae in shallow coastal waters need mechanisms for short-term acclimation to fast changes in their environment. Of major importance are mechanisms that regulate the efficiency of photosynthesis by protecting PS II from photo-oxidative damage. Carotenoids, xanthophyll cycles and non-photochemical quenching (NPQ) are central constituents of such protection mechanisms. Red algae as a group do not have a universal carotenoid composition. We screened ten red algal species and selected two species, originating from similar ecological conditions but with different carotenoid compositions, for use in irradiance-acclimation experiments. We selected the tropical intertidal species Gracilaria domingensis and Kappaphycus alvarezii with antheraxanthin and lutein as major xanthophylls, respectively. Simultaneous in vivo fluorescence and O₂ evolution experiments were performed at different irradiance levels, which allowed a direct comparison of overall photosynthetic performance with NPQ. Interconversions of xanthophylls (violaxanthin, zeaxanthin, β-cryptoxanthin and one unidentified carotenoid) did occur in G. domingensis, but not in response to sudden exposure to light. Thus, NPQ was not correlated with any xanthophyll cycle during short-term acclimation to light. G. domingensis had five times higher weight-specific photosynthetic rates than K. alvarezii, which can be explained by the thicker thallus of K. alvarezii. Chlorophyll-specific gross photosynthetic rates were higher in K. alvarezii, but net rates were the same for both species. G. domingensis showed an immediate strong onset of NPQ upon exposure to irradiance, followed by downregulation to the NPQ level required. In K. alvarezii NPQ increased slowly until the required NPQ level was reached. At high irradiance G. domingensis downregulated photosynthesis while K. alvarezii continued to produce O₂ even at 2,000 μmol photons m⁻² s⁻¹ without NPQ increase. The strategy of K. alvarezii may provide short-term gains but with the risk of oxidative damage. The fast onset of NPQ in G. domingensis even at subsaturating irradiance as well as downregulation of photosynthesis when NPQ is saturated might provide this species with a competitive advantage under conditions of changing irradiance in the field.     

Individual recognition and potential recognition errors in parent–offspring communication

The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalizations are the most commonly used cues in avian parent–offspring communication, and it has been shown in several species that fledglings respond specifically to their parents' contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect recognition errors or alternatively a strategy of fledglings to obtain food or other direct benefits from unrelated adult birds. In a playback experiment, we tested whether zebra finch Taeniopygia guttata fledglings perceive variation in adult call signatures to recognize their parents and whether the propensity to respond to unrelated individuals is related to the gender of adults and to signal properties of male and female calls. Male calls are learnt and show high intra-sexual variation, which may improve the accurate recognition of the father's individual signature. In contrast, calls of adult females are innate, show lower intra-sexual variation such that the mother's call is more likely to be confused with another female call. We demonstrate that fledglings are able to recognize their parents. In addition, fledglings reacted more strongly to unrelated females compared with unrelated males. Our findings suggest that responses to unrelated adults may reflect recognition errors and indicate the importance of variation in identity signals for individual recognition processes in parent–offspring communication.     

Egg and early larval stages of Baltic cod, Gadus morhua, are robust to high levels of ocean acidification

The accumulation of carbon dioxide in the atmosphere will lower the pH in ocean waters, a process termed ocean acidification (OA). Despite its potentially detrimental effects on calcifying organisms, experimental studies on the possible impacts on fish remain scarce. While adults will most likely remain relatively unaffected by changes in seawater pH, early life-history stages are potentially more sensitive, due to the lack of gills with specialized ion-regulatory mechanisms. We tested the effects of OA on growth and development of embryos and larvae of eastern Baltic cod, the commercially most important fish stock in the Baltic Sea. Cod were reared from newly fertilized eggs to early non-feeding larvae in 5 different experiments looking at a range of response variables to OA, as well as the combined effect of CO₂ and temperature. No effect on hatching, survival, development, and otolith size was found at any stage in the development of Baltic cod. Field data show that in the Bornholm Basin, the main spawning site of eastern Baltic cod, in situ levels of pCO₂ are already at levels of 1,100 μatm with a pH of 7.2, mainly due to high eutrophication supporting microbial activity and permanent stratification with little water exchange. Our data show that the eggs and early larval stages of Baltic cod seem to be robust to even high levels of OA (3,200 μatm), indicating an adaptational response to CO₂.     

Development and Evaluation of Bankfull Hydraulic Geometry Relationships for the Physiographic Regions of the United States

Bankfull hydraulic geometry relationships are used to estimate channel dimensions for streamflow simulation models, which require channel geometry data as input parameters. Often, one nationwide curve is used across the entire United States (U.S.) (e.g., in Soil and Water Assessment Tool), even though studies have shown that the use of regional curves can improve the reliability of predictions considerably. In this study, regional regression equations predicting bankfull width, depth, and cross‐sectional area as a function of drainage area are developed for the Physiographic Divisions and Provinces of the U.S. and compared to a nationwide equation. Results show that the regional curves at division level are more reliable than the nationwide curve. Reliability of the curves depends largely on the number of observations per region and how well the sample represents the population. Regional regression equations at province level yield even better results than the division‐level models, but because of small sample sizes, the development of meaningful regression models is not possible in some provinces. Results also show that drainage area is a less reliable predictor of bankfull channel dimensions than bankfull discharge. It is likely that the regional curves can be improved using multiple regression models to incorporate additional explanatory variables.     

Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA

We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products ¹³¹I, ¹³²I, ¹³²Te, ¹³⁴Cs, and ¹³⁷Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity from radionuclides attached to particulate matter amounted to 4.4 ± 1.3 mBq m⁻³ of ¹³¹I on 19-20 March.