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In digital soil mapping (DSM), soil maps are usually produced in a univariate manner, that is, each soil map is produced independently and therefore, when multiple soil properties are mapped the underlying dependence structure between these soil properties is ignored. This may lead to inconsistent predictions and simulations. For example, soil organic carbon (SOC) and total nitrogen (TN) maps produced independently may show unrealistic carbon–nitrogen (C:N) ratios. In the last decade the production of soil maps with machine learning models has become increasingly popular as these models are able to capture complex non-linear relationships between soil properties and environmental covariates. However, producing soil maps with multivariate machine learning models is still lacking and requires much investigation in DSM. In this paper we present the combined modelling of multiple soil properties with a multivariate random forest (MRF) model. We applied this model to mapping SOC and TN, and we compared it with results of two separate univariate random forest (RF) models. The comparison was done by means of stochastic simulations determined by sampling from the conditional distributions of the soil properties, given the covariates, as estimated by quantile regression forest. The results show that the MRF model is superior in terms of maintaining the dependence structure between SOC and TN, and consequently, is also able to produce more realistic C:N ratios. The models were also compared on the basis of prediction accuracy using commonly used accuracy metrics such as the root mean square error (RMSE). We found that the accuracy of the MRF model (RMSE-SOC=40.04, RMSE-TN=2.26, RMSE-CN=3.58) is comparable to that of the univariate RF models (RMSE-SOC=39.76, RMSE-TN=2.26, RMSE-CN=3.65). We performed the same comparisons between a regression co-kriging model and two separate regression kriging models, and made similar conclusions.

Shrimp culture rearing systems are dynamic with numerous processes influencing system performance. This research investigated the effects of stocking density, feeding level and C:N ratio on shrimp production, water quality and microbial community composition in a biofloc shrimp rearing system, using a 3 × 3 factorial design. Pacific white shrimp (Litopenaeus vannamei) were stocked at 27, 120, or 300 individual m−3 and fed 100, 80 or 60% of the recommended daily feed ration. For each combination of stocking density and feeding level, C:N ratios of 7.4, 12 or 16 were created by feeding a mixture of casava and rice bran besides the daily pelleted feed input to culture tanks. After 12 weeks of culture, the harvested shrimp biomass was the highest in the rearing tanks with the highest stocking density, feeding level and C:N ratio (P < 0.05), while the individual shrimp size at harvest decreased with increasing stocking density (P < 0.05). Biofloc biomass (e.g. total suspended solids TSS, volatile suspended solids VSS) and, to a lesser degree, water quality (total ammonia nitrogen TAN, NO2-N) were affected by 2 and 3-way interactions of the main tested factors. The ash, protein, fat and nitrogen free extract (NFE) content in biofloc were affected by stocking density (P < 0.05), and ash and NFE content by C:N ratio (P < 0.05). Regarding the microbial community composition in the biofloc at the highest stocking density, increasing feeding level and C:N ratio led to an increasing microbial richness and diversity (P < 0.05) as a result of nutrient input. Overall, the shrimp production and biofloc biomass were influenced in a similar way by the stocking density, feeding level and C:N ratio applied in the biofloc system. Future research should focus on how the type of carbohydrates and methods of administration affect shrimp growth and biofloc formation, and how this may promote health benefits through the microbial community manipulation.

Juveniles from two separately bred families of the Manila clam Ruditapes philippinarum were used to constitute fast (F)- and slow (S)-growing groups by size segregation. The growth phenotypes that resulted from these 4 family*growth category combinations were then used to measure elemental C and N balances in the acute and chronic responses to two different microalgal diets that were isocaloric but differed (x3) in their protein:energy ratios. Both diets were based on the same phytoplankton species (Rhodomonas lens) that were harvested in the exponential (low C:N ratio) or stationary (high C:N ratio) phases of an indoor culture. Aims were to assess the differential acquisition and processing of elemental nutrients according to differences in their dietary availability and the variable requirements set by the growth trends exhibited by different phenotypes. Clams fed the high N diet achieved the highest C and N balances through a combination of higher feeding rates and absorption efficiencies of overall organics. However, the main differential effects were associated with increased absorption efficiencies for N relative to C, which were particularly observed in clams subjected to chronic N deficit in the diet. This occurred in all growth phenotypes and resulted in the partial homeostatic regulation of nutrient imbalance operating at the preabsorptive level. Further adjustments occurred at the postabsorptive level with increased N disposal in the form of ammonia excretion and the resulting decrease of metabolic C:N indices recorded in clams fed the high N diets. The main phenotypic differences were observed in the intrafamily (F vs. S growth groups) rather than in the interfamily comparisons, with F clams exceeding the absorption rate of nutrients (both C and N) of S clams by 50%. Physiological responses to the acute dietary change were found to be faster in F clams, indicative of a higher plasticity of this phenotype. Whereas, stoichiometric adjustments by S clams re

An increase in respiration (RSDA) associated with food ingestion (I) was estimated from routine rates (Rroutine) determined in the absence of food with sealed-chamber methods. Based on regression analyses of RSDA on I for metazooplankton in the laboratory, the fraction of I allocated to RSDA was calculated to be 0.10. Likely food ingestion of metazooplankton in the field (Ifield) was derived from “basic balanced equations” in which parameters such as Rroutine, laboratory-obtained food absorption efficiency (AE) and gross growth efficiency (K1) were incorporated (I&M model). Based on differences in AE values, metazooplankton were separated into particle-feeders (herbivores, omnivores) and carnivores and RSDA was computed to be 0.37 times Rroutine for the former and 0.25 times Rroutine for the latter. Hence, realistic respiration rates of metazooplankton feeding in the field (Rfield = RSDA + Rroutine) accounted for 1.37 times Rroutine for particle-feeders and 1.25 times Rroutine for carnivores. The increase in ammonia excretion (ESDA) accompanied by SDA in particle-feeders and carnivores was calculated from RSDA coupled with carbon-to-nitrogen (C:N by mass) ratios of possible natural foods (6.5 for the former and 4.5 for the latter). Results indicated that ESDA is 0.080 times RSDA for particle-feeders, and 0.116 times RSDA for carnivores.

An increase in respiration (RSDA) associated with food ingestion (I) was estimated from routine rates (Rroutine) determined in the absence of food with sealed-chamber methods. Based on regression analyses of RSDA on I for metazooplankton in the laboratory, the fraction of I allocated to RSDA was calculated to be 0.10. Likely food ingestion of metazooplankton in the field (Ifield) was derived from “basic balanced equations” in which parameters such as Rroutine, laboratory-obtained food absorption efficiency (AE) and gross growth efficiency (K1) were incorporated (I&M model). Based on differences in AE values, metazooplankton were separated into particle-feeders (herbivores, omnivores) and carnivores and RSDA was computed to be 0.37 times Rroutine for the former and 0.25 times Rroutine for the latter. Hence, realistic respiration rates of metazooplankton feeding in the field (Rfield = RSDA + Rroutine) accounted for 1.37 times Rroutine for particle-feeders and 1.25 times Rroutine for carnivores. The increase in ammonia excretion (ESDA) accompanied by SDA in particle-feeders and carnivores was calculated from RSDA coupled with carbon-to-nitrogen (C:N by mass) ratios of possible natural foods (6.5 for the former and 4.5 for the latter). Results indicated that ESDA is 0.080 times RSDA for particle-feeders, and 0.116 times RSDA for carnivores.

An increase in respiration (RSDA) associated with food ingestion (I) was estimated from routine rates (Rroutine) determined in the absence of food with sealed-chamber methods. Based on regression analyses of RSDA on I for metazooplankton in the laboratory, the fraction of I allocated to RSDA was calculated to be 0.10. Likely food ingestion of metazooplankton in the field (Ifield) was derived from “basic balanced equations” in which parameters such as Rroutine, laboratory-obtained food absorption efficiency (AE) and gross growth efficiency (K1) were incorporated (I&M model). Based on differences in AE values, metazooplankton were separated into particle-feeders (herbivores, omnivores) and carnivores and RSDA was computed to be 0.37 times Rroutine for the former and 0.25 times Rroutine for the latter. Hence, realistic respiration rates of metazooplankton feeding in the field (Rfield = RSDA + Rroutine) accounted for 1.37 times Rroutine for particle-feeders and 1.25 times Rroutine for carnivores. The increase in ammonia excretion (ESDA) accompanied by SDA in particle-feeders and carnivores was calculated from RSDA coupled with carbon-to-nitrogen (C:N by mass) ratios of possible natural foods (6.5 for the former and 4.5 for the latter). Results indicated that ESDA is 0.080 times RSDA for particle-feeders, and 0.116 times RSDA for carnivores.

In the biofloc systems the continuous application of carbon sources led to the assimilation of nitrogenous nutrients and formation of heterotrophic bacterial biomass. The present experiment was conducted in 0.22m3 capacity tanks in the triplicate to find out the structure, proximate composition, nutrient dynamics and growth characteristics of Penaeus vannamei in indoor biofloc systems with three different salinities (35, 20 and 5ppt) and carbon sources (molasses, sugar and rice flour) with an estimated C:N ratio of 15:1. pre salinity acclimatized P. vannamei , specific pathogen free seeds (0.2±0.04g) were stocked @100 numbers per m3 and fed 4 times a day based on the % of body weight (from 22% to 2.5%) and reared for 10 weeks. The results revealed that the carbon application at different salinities significantly influenced the biofloc structure (Scanning Electron Microscopic images of biofloc 4000x) showed round and rod-shaped structures. Proximate composition: crude protein (p<0.001), ether extract (p<0.001) and crude fibre (p<0.05) showed significant difference between treatments. Similarly, elemental carbon composition (p<0.01), nitrogenous waste assimilation of TAN (p<0.01), nitrite (p<0.05), and nitrate (p<0.05) showed significant differences in the treatments vs. the control group. The variables also influenced the microbiota abundance {the metagenomics analysis of biofloc showed Bray-Curtis overall average dissimilarity index of 81%, and it varied from 49% to 100% between treatments & controls} and growth characteristics {average body weight (p<0.001) and survival rate (p<0.01) between treatments and controls} of P. vannamei indoor biofloc systems. Hence, the application of carbon sources at different salinities influenced the biofloc structure, proximate, elemental carbon composition, biofloc microbiota abundance, enhanced the nitrogenous waste assimilation and growth performance of P. vannamei in indoor biofloc systems.

In this study, we have for the first time analyzed diel microzooplankton grazing selectivity on unicellular cyanobacterial diazotroph (i.e., Crocosphaera watsonii WH8501) and non-diazotrophic unicellular microalga (i.e., Chlorella autotrophica). A mixed diet consisting of these two phytoplankton was supplied to four species of protistal grazers during daytime and nighttime, respectively. C. watsonii fixes nitrogen during nighttime and showed a stronger diel pattern of cellular C:N ratio than C. autotrophica. All four grazers ingested more nighttime C. watsonii than daytime C. watsonii, suggesting the diazotroph became more nutritious (inferred by C:N ratio) and thus a preferred prey for grazers when it fixes nitrogen. In particular, Oxyrrhis marina changed from preferring C. autotrophica during daytime to preferring C. watsonii during nighttime. The rest grazers showed species-specific grazing preferences, which could be explained by extracellular polysaccharide production of C. watsonii, feeding mode, cingulum size and cell size of grazers.

In this study, we have for the first time analyzed diel microzooplankton grazing selectivity on unicellular cyanobacterial diazotroph (i.e., Crocosphaera watsonii WH8501) and non-diazotrophic unicellular microalga (i.e., Chlorella autotrophica). A mixed diet consisting of these two phytoplankton was supplied to four species of protistal grazers during daytime and nighttime, respectively. C. watsonii fixes nitrogen during nighttime and showed a stronger diel pattern of cellular C:N ratio than C. autotrophica. All four grazers ingested more nighttime C. watsonii than daytime C. watsonii, suggesting the diazotroph became more nutritious (inferred by C:N ratio) and thus a preferred prey for grazers when it fixes nitrogen. In particular, Oxyrrhis marina changed from preferring C. autotrophica during daytime to preferring C. watsonii during nighttime. The rest grazers showed species-specific grazing preferences, which could be explained by extracellular polysaccharide production of C. watsonii, feeding mode, cingulum size and cell size of grazers.

Soil organic carbon (SOC) and soil carbon-to-nitrogen ratio (C:N) are the main indicators of soil quality and health and play an important role in maintaining soil quality. Together with Landsat, the improved spatial and temporal resolution Sentinel sensors provide the potential to investigate soil information on various scales. We analyzed and compared the potential of satellite sensors (Landsat-8, Sentinel-2 and Sentinel-3) with various spatial and temporal resolutions to predict SOC content and C:N ratio in Switzerland. Modeling was carried out at four spatial resolutions (800 m, 400 m, 100 m and 20 m) using three machine learning techniques: support vector machine (SVM), boosted regression tree (BRT) and random forest (RF). Soil prediction models were generated in these three machine learners in which 150 soil samples and different combinations of environmental data (topography, climate and satellite imagery) were used as inputs. The prediction results were evaluated by cross-validation. Our results revealed that the model type, modeling resolution and sensor selection greatly influenced outputs. By comparing satellite-based SOC models, the models built by Landsat-8 and Sentinel-2 performed the best and the worst, respectively. C:N ratio prediction models based on Landsat-8 and Sentinel-2 showed better results than Sentinel-3. However, the prediction models built by Sentinel-3 had competitive or better accuracy at coarse resolutions. The BRT models constructed by all available predictors at a resolution of 100 m obtained the best prediction accuracy of SOC content and C:N ratio; their relative improvements (in terms of R2) compared to models without remote sensing data input were 29.1% and 58.4%, respectively. The results of variable importance revealed that remote sensing variables were the best predictors for our soil prediction models. The predicted maps indicated that the higher SOC content was mainly distributed

In this study, we have for the first time analyzed diel microzooplankton grazing selectivity on unicellular cyanobacterial diazotroph (i.e., Crocosphaera watsonii WH8501) and non-diazotrophic unicellular microalga (i.e., Chlorella autotrophica). A mixed diet consisting of these two phytoplankton was supplied to four species of protistal grazers during daytime and nighttime, respectively. C. watsonii fixes nitrogen during nighttime and showed a stronger diel pattern of cellular C:N ratio than C. autotrophica. All four grazers ingested more nighttime C. watsonii than daytime C. watsonii, suggesting the diazotroph became more nutritious (inferred by C:N ratio) and thus a preferred prey for grazers when it fixes nitrogen. In particular, Oxyrrhis marina changed from preferring C. autotrophica during daytime to preferring C. watsonii during nighttime. The rest grazers showed species-specific grazing preferences, which could be explained by extracellular polysaccharide production of C. watsonii, feeding mode, cingulum size and cell size of grazers.

We describe the ontogenetic variation in elemental and stoichiometric composition of two copepod species with very contrasted life history patterns, the calanoid Paracartia grani and the cyclopoid Oithona davisae. The first species is a broadcasting, highly productive copepod, whereas the latter is an egg-carrying copepod, much less productive. We reared cultures of both species under conditions of excess food and analyzed their C, N and P composition, and their molar ratios, along development. Both species differed on their specific P content, whereas the specific C and N content were similar. As expected, the specific P content of P. grani was higher, resulting in lower C:P and N:P ratios. Furthermore, we compared our elemental composition data with previously reported stage-specific (nauplii and adult female) maximum growth rates of these two species. We found that for O. davisae, the ontogenetic variation in specific P content agreed with the reported differences in growth rate along development; however, in the case of P. grani, in which juvenile and adult maximum growth rates are similar, the variations in specific P content along development did not reflect the growth rate pattern

After termination, cover crop residue can suppress weeds by reducing sunlight, decreasing soil temperature, and providing a physical barrier. Experiments were implemented to monitor horseweed suppression from different cover crops as well as two fall-applied residual herbicide treatments. Results suggest that cover crops, other than forage radish in monoculture, can suppress horseweed more consistently than flumioxazin + paraquat or metribuzin + chlorimuron-ethyl. Cover crop biomass is positively correlated to weed suppression. Subsequent experiments were designed to determine the amount of weed suppression from different cover crop treatments and if carbon to nitrogen (C:N) ratios or lignin content are also correlated to weed suppression or cover crop residue thickness. Results indicate that cereal rye alone and mixtures containing cereal rye produced the most biomass and suppressed weeds more than hairy vetch, crimson clover, and forage radish alone. Analyses indicate that lignin, as well as biomass, is an important indicator of weed suppression. While cover crops provide many benefits, integrating cover crops into production can be difficult. Hairy vetch, a legume cover crop, can become a weed in subsequent seasons. Multiple experiments were implemented to determine germination phenology and viability of two hairy vetch cultivars, Groff and Purple Bounty, and to determine when viable seed are produced. Almost all germination occurred in the initial cover crop growing season for both cultivars. Both cultivars had <1% of viable seed at the termination of the experiment. These results indicate that seed dormancy is not the primary cause of weediness.

In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models. The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter systems, the POM composition varies in space, with 1) systems where POM is highly composed of phytoplankton (≥ 93%), 2) systems characterized by a non-negligible contribution of benthic (8 to 19%) and/or riverine (7 to 19%) sources, and 3) the Mediterranean systems characterized by the contribution of diazotroph organisms (ca. 14%). A continent-to-ocean gradient of riverine and/or benthic POM contribution is observed. Finally, time series reveal 1) seasonal variations of POM composition, 2) differences in seasonality between systems, and 3) an inshore-offshore gradient of seasonality within each system that were sampled at several stations. Spatial and seasonal patterns of POM composition are mainly due to local to regional processes such as hydrodynamics and sedimentary hydrodynamic (e.g. resuspension processes, changes in river flows, wind patterns influencing along-shore currents) but also due to the geomorphology of the systems (depth of the water column, distance to the shore). Future studies investigating the link between these forcings and POM composition would help to better understand the dynamics of POM composition in coastal systems.

In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models. The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter systems, the POM composition varies in space, with 1) systems where POM is highly composed of phytoplankton (≥ 93%), 2) systems characterized by a non-negligible contribution of benthic (8 to 19%) and/or riverine (7 to 19%) sources, and 3) the Mediterranean systems characterized by the contribution of diazotroph organisms (ca. 14%). A continent-to-ocean gradient of riverine and/or benthic POM contribution is observed. Finally, time series reveal 1) seasonal variations of POM composition, 2) differences in seasonality between systems, and 3) an inshore-offshore gradient of seasonality within each system that were sampled at several stations. Spatial and seasonal patterns of POM composition are mainly due to local to regional processes such as hydrodynamics and sedimentary hydrodynamic (e.g. resuspension processes, changes in river flows, wind patterns influencing along-shore currents) but also due to the geomorphology of the systems (depth of the water column, distance to the shore). Future studies investigating the link between these forcings and POM composition would help to better understand the dynamics of POM composition in coastal systems.

Rice straw is one of the most abundant lignocellulosic agricultural residues on the world, after residues produced by maize and wheat crops, with an estimated global production of 1000 million tones according to FAO statistics. In the context of modern agriculture, it is essential to achieve an environmentally sustainable management of this resource, through the incorporation of rice straw into the soil, in order to achieve nutrient recycling avoiding the incorporation of pathogens into the system and the losses of nitrogen due to soil microbial biomass immobilization. In this context, the objective of this work consisted in the evaluation of a mixed microbial inoculum with degrading potential of rice straw from commercial products based on the fungus Trichoderma spp. and aerobic endospore forming bacteria. It was also used a plant growth promoting bacteria at the time of planting, in order to take advantage of nutrients released from RS decomposition and improve its biological activity. These microbial treatments, were evaluated at different concentrations of inorganic nitrogen amendments that allowed different levels of rice straw´s C:N ratio, favoring the degradation process. Overall results allowed to identify that the application of a nitrogen amendment to rice straw up to C:N 35, plus an additional dose of urea at the time of rice seeds planting, was the most adequate treatment to potentiate the effect of the microorganisms and to increase or maintain the agronomic variables obtained through a conventional fertilization management of the crop., El tamo de arroz es uno de los residuos agrícolas lignocelulósicos más abundantes en el planeta, luego de los residuos producidos por los cultivos de maíz y trigo, con una producción mundial estimada de 1000 millones de toneladas según estadísticas de la FAO. En el contexto de la agricultura moderna es determinante lograr un manejo ambientalmente sostenible de este recurso mediante su incorporación al suelo, de tal forma que se logre el reciclaje de nutrientes, evitando la incorporación de patógenos al sistema y la inmovilización de elementos como el nitrógeno por la comunidad microbiana. El objetivo de este trabajo consistió en la evaluación de un inoculo microbiano mixto a partir de productos comerciales basados en hongos del género Trichoderma y bacterias aerobias formadoras de endosporas, con potencial degradador del tamo de arroz, así como el empleo de bacterias promotoras de crecimiento vegetal al momento de la siembra, que pudieran aprovechar los nutrientes del proceso de descomposición del tamo de arroz, potenciando su actividad biológica. Los tratamientos fueron evaluados bajo diferentes relaciones C:N del tamo de arroz que favorecieran el proceso de degradación, mediante la adición de nitrógeno inorgánico. Los resultados del trabajo permitieron identificar que la aplicación de una enmienda de nitrógeno a una relación C:N 35 más una dosis adicional de urea al momento de la siembra de las semillas de arroz, fue el tratamiento más adecuado para potenciar el efecto de los microorganismos e incrementar las variables agronómicas obtenidas mediante un esquema de fertilización convencional del cultivo.

A smaller literature study and a data retrieval on N2O emissions, N mineralization and C:N ratios from projects recently conducted at SLU and from other Swedish sites have been performed to evaluate whether the current IPCC Tier 1 approach with a default emission factor of 1% (EF1) for N2O emissions from agricultural soils and other land use categories should be changed to a higher Tier with more specific EFs. The study showed that the use of a default N2O EF of 1% of the N applied to soils would either under- or overestimate N2O emissions. It was also concluded that there is no relationship between total N input and N2O emissions, i.e. high fertilizer input must not be related to high N2O emissions and low fertilizer input can result in high N2O emissions. Even though N2O emissions from different Swedish land use categories were lower as the default EF1 in 8 of the 21 reported data sets, there is clear evidence to change from the IPCC Tier 1 approach for N2O emissions to more adjusted EFs related to a country-specific methodology. The strong relationship between C:N ratios and N2O emissions from drained forested histosols may be used to improve our ability to predict N2O emissions from other land use categories such as grassland and cropland.

In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models. The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter systems, the POM composition varies in space, with 1) systems where POM is highly composed of phytoplankton (≥ 93%), 2) systems characterized by a non-negligible contribution of benthic (8 to 19%) and/or riverine (7 to 19%) sources, and 3) the Mediterranean systems characterized by the contribution of diazotroph organisms (ca. 14%). A continent-to-ocean gradient of riverine and/or benthic POM contribution is observed. Finally, time series reveal 1) seasonal variations of POM composition, 2) differences in seasonality between systems, and 3) an inshore-offshore gradient of seasonality within each system that were sampled at several stations. Spatial and seasonal patterns of POM composition are mainly due to local to regional processes such as hydrodynamics and sedimentary hydrodynamic (e.g. resuspension processes, changes in river flows, wind patterns influencing along-shore currents) but also due to the geomorphology of the systems (depth of the water column, distance to the shore). Future studies investigating the link between these forcings and POM composition would help to better understand the dynamics of POM composition in coastal systems.

Rice straw is one of the most abundant lignocellulosic agricultural residues on the world, after residues produced by maize and wheat crops, with an estimated global production of 1000 million tones according to FAO statistics. In the context of modern agriculture, it is essential to achieve an environmentally sustainable management of this resource, through the incorporation of rice straw into the soil, in order to achieve nutrient recycling avoiding the incorporation of pathogens into the system and the losses of nitrogen due to soil microbial biomass immobilization. In this context, the objective of this work consisted in the evaluation of a mixed microbial inoculum with degrading potential of rice straw from commercial products based on the fungus Trichoderma spp. and aerobic endospore forming bacteria. It was also used a plant growth promoting bacteria at the time of planting, in order to take advantage of nutrients released from RS decomposition and improve its biological activity. These microbial treatments, were evaluated at different concentrations of inorganic nitrogen amendments that allowed different levels of rice straw´s C:N ratio, favoring the degradation process. Overall results allowed to identify that the application of a nitrogen amendment to rice straw up to C:N 35, plus an additional dose of urea at the time of rice seeds planting, was the most adequate treatment to potentiate the effect of the microorganisms and to increase or maintain the agronomic variables obtained through a conventional fertilization management of the crop., El tamo de arroz es uno de los residuos agrícolas lignocelulósicos más abundantes en el planeta, luego de los residuos producidos por los cultivos de maíz y trigo, con una producción mundial estimada de 1000 millones de toneladas según estadísticas de la FAO. En el contexto de la agricultura moderna es determinante lograr un manejo ambientalmente sostenible de este recurso mediante su incorporación al suelo, de tal forma que se logre el reciclaje de nutrientes, evitando la incorporación de patógenos al sistema y la inmovilización de elementos como el nitrógeno por la comunidad microbiana. El objetivo de este trabajo consistió en la evaluación de un inoculo microbiano mixto a partir de productos comerciales basados en hongos del género Trichoderma y bacterias aerobias formadoras de endosporas, con potencial degradador del tamo de arroz, así como el empleo de bacterias promotoras de crecimiento vegetal al momento de la siembra, que pudieran aprovechar los nutrientes del proceso de descomposición del tamo de arroz, potenciando su actividad biológica. Los tratamientos fueron evaluados bajo diferentes relaciones C:N del tamo de arroz que favorecieran el proceso de degradación, mediante la adición de nitrógeno inorgánico. Los resultados del trabajo permitieron identificar que la aplicación de una enmienda de nitrógeno a una relación C:N 35 más una dosis adicional de urea al momento de la siembra de las semillas de arroz, fue el tratamiento más adecuado para potenciar el efecto de los microorganismos e incrementar las variables agronómicas obtenidas mediante un esquema de fertilización convencional del cultivo.

A smaller literature study and a data retrieval on N2O emissions, N mineralization and C:N ratios from projects recently conducted at SLU and from other Swedish sites have been performed to evaluate whether the current IPCC Tier 1 approach with a default emission factor of 1% (EF1) for N2O emissions from agricultural soils and other land use categories should be changed to a higher Tier with more specific EFs. The study showed that the use of a default N2O EF of 1% of the N applied to soils would either under- or overestimate N2O emissions. It was also concluded that there is no relationship between total N input and N2O emissions, i.e. high fertilizer input must not be related to high N2O emissions and low fertilizer input can result in high N2O emissions. Even though N2O emissions from different Swedish land use categories were lower as the default EF1 in 8 of the 21 reported data sets, there is clear evidence to change from the IPCC Tier 1 approach for N2O emissions to more adjusted EFs related to a country-specific methodology. The strong relationship between C:N ratios and N2O emissions from drained forested histosols may be used to improve our ability to predict N2O emissions from other land use categories such as grassland and cropland.

In coastal systems, the multiplicity of sources fueling the pool of particulate organic matter (POM) leads to divergent estimations of POM composition. Eleven systems (two littoral systems, eight embayments and semi-enclosed systems and one estuary) distributed along the three maritime façades of France were studied for two to eight years in order to quantify the relative contribution of organic matter sources to the surface-water POM pool in coastal systems. This study was based on carbon and nitrogen elemental and isotopic ratios, used for running mixing models. The POM of the estuary is dominated by terrestrial material (93% on average), whereas the POM of the other systems is dominated by phytoplankton (84% on average). Nevertheless, for the latter systems, the POM composition varies in space, with 1) systems where POM is highly composed of phytoplankton (≥ 93%), 2) systems characterized by a non-negligible contribution of benthic (8 to 19%) and/or riverine (7 to 19%) sources, and 3) the Mediterranean systems characterized by the contribution of diazotroph organisms (ca. 14%). A continent-to-ocean gradient of riverine and/or benthic POM contribution is observed. Finally, time series reveal 1) seasonal variations of POM composition, 2) differences in seasonality between systems, and 3) an inshore-offshore gradient of seasonality within each system that were sampled at several stations. Spatial and seasonal patterns of POM composition are mainly due to local to regional processes such as hydrodynamics and sedimentary hydrodynamic (e.g. resuspension processes, changes in river flows, wind patterns influencing along-shore currents) but also due to the geomorphology of the systems (depth of the water column, distance to the shore). Future studies investigating the link between these forcings and POM composition would help to better understand the dynamics of POM composition in coastal systems.

Rice straw is one of the most abundant lignocellulosic agricultural residues on the world, after residues produced by maize and wheat crops, with an estimated global production of 1000 million tones according to FAO statistics. In the context of modern agriculture, it is essential to achieve an environmentally sustainable management of this resource, through the incorporation of rice straw into the soil, in order to achieve nutrient recycling avoiding the incorporation of pathogens into the system and the losses of nitrogen due to soil microbial biomass immobilization. In this context, the objective of this work consisted in the evaluation of a mixed microbial inoculum with degrading potential of rice straw from commercial products based on the fungus Trichoderma spp. and aerobic endospore forming bacteria. It was also used a plant growth promoting bacteria at the time of planting, in order to take advantage of nutrients released from RS decomposition and improve its biological activity. These microbial treatments, were evaluated at different concentrations of inorganic nitrogen amendments that allowed different levels of rice straw´s C:N ratio, favoring the degradation process. Overall results allowed to identify that the application of a nitrogen amendment to rice straw up to C:N 35, plus an additional dose of urea at the time of rice seeds planting, was the most adequate treatment to potentiate the effect of the microorganisms and to increase or maintain the agronomic variables obtained through a conventional fertilization management of the crop., El tamo de arroz es uno de los residuos agrícolas lignocelulósicos más abundantes en el planeta, luego de los residuos producidos por los cultivos de maíz y trigo, con una producción mundial estimada de 1000 millones de toneladas según estadísticas de la FAO. En el contexto de la agricultura moderna es determinante lograr un manejo ambientalmente sostenible de este recurso mediante su incorporación al suelo, de tal forma que se logre el reciclaje de nutrientes, evitando la incorporación de patógenos al sistema y la inmovilización de elementos como el nitrógeno por la comunidad microbiana. El objetivo de este trabajo consistió en la evaluación de un inoculo microbiano mixto a partir de productos comerciales basados en hongos del género Trichoderma y bacterias aerobias formadoras de endosporas, con potencial degradador del tamo de arroz, así como el empleo de bacterias promotoras de crecimiento vegetal al momento de la siembra, que pudieran aprovechar los nutrientes del proceso de descomposición del tamo de arroz, potenciando su actividad biológica. Los tratamientos fueron evaluados bajo diferentes relaciones C:N del tamo de arroz que favorecieran el proceso de degradación, mediante la adición de nitrógeno inorgánico. Los resultados del trabajo permitieron identificar que la aplicación de una enmienda de nitrógeno a una relación C:N 35 más una dosis adicional de urea al momento de la siembra de las semillas de arroz, fue el tratamiento más adecuado para potenciar el efecto de los microorganismos e incrementar las variables agronómicas obtenidas mediante un esquema de fertilización convencional del cultivo.

1. Plant diversity enhances many ecosystem functions, including root biomass production, which drives soil carbon input. Although root decomposition accounts for a large proportion of carbon input for soil, little is known about plant diversity effect on this process. Plant diversity may affect root decomposition in two non-exclusive ways: by providing roots of different substrate quality (e.g. root chemistry) and/or by altering the soil environment (e.g. microclimate).2. To disentangle these two pathways, we conducted three decomposition experiments using a litter-bag approach in a grassland biodiversity experiment. We hypothesized that: (i) plant species richness negatively affects substrate quality (indicated by increased C:N ratios), which we tested by decomposing roots collected from each experimental plot in one common plot; (ii) plant species richness positively affects soil environment (indicated by increased soil water content), which we tested by decomposing standardized roots in all experimental plots; (iii) the overall effect of plant species richness on root decomposition, due to the contrast between quality and environmental effects, is neutral, which we tested by decomposing community roots in their ‘home’ plots.3. Plant species richness negatively affected root decomposition in all three experiments. The negative effect of plant species richness on substrate quality was largely explained by increased root C:N ratios along the diversity gradient. Functional group presence explained more variance in substrate quality than species richness. Here, the presence of grasses negatively affected substrate quality and root C:N ratios, while the presence of legumes and small herbs had positive effects. Plant species richness had a negative effect on soil environment despite its positive effect on soil water content which is known to stimulate decomposition. We argue that – instead of soil water content – a combined effect of soil temperature and seasonality mig

Plant diversity is known to influence the abundance and diversity of belowground biota; however, patterns are not well predictable and there is still much unknown about the driving mechanisms. We analyzed changes in soil nematode community composition as affected by long-term manipulations of plant species and functional group diversity in a field experiment with plant species diversity controlled by sowing a range of 1-60 species mixtures and controlling non-sown species by hand weeding. Nematode communities contain a variety of species feeding on bacteria, fungi, plants, invertebrates, while some are omnivorous. We analyzed responses of nematode abundance and diversity to plant species and functional diversity, and used structural equation modeling (SEM) to explore the possible mechanisms underlying the observed patterns. The abundance of individuals of all nematode feeding types, except for predatory nematodes, increased with both plant species and plant functional group diversity. The abundance of microbial-feeding nematodes was related positively to aboveground plant community biomass, whereas abundance of plant-feeding nematodes was related positively to shoot C:N ratio. The abundance of predatory nematodes, in turn, was positively related to numbers of plant-feeding nematodes, but not to the abundance of microbial feeders. Interestingly, the numbers of plant-feeding nematodes per unit root mass were lowest in the high-diversity plant communities, pointing at reduced exposure to belowground herbivores when plants grow in species-diverse communities. Taxon richness of plant-feeding and microbialfeeding nematodes increased with plant species and plant functional group diversity. Increasing plant functional group diversity also enhanced taxon richness of predatory nematodes. The SEM suggests that bottom-up control effects of plant species and plant functional group diversity on abundance of nematodes in the various feeding types predominantly involve mechanistic

1. This study investigated the factors underlying the variability of needle and soil elemental composition and stoichiometry and their relationships with growth in Pinus sylvestris forests throughout the species' distribution in Europe by analyzing data from 2245 forest stands. 2. Needle N concentrations and N:P ratios were positively correlated with total atmospheric N deposition, whereas needle P concentrations were negatively correlated. These relationships were especially pronounced at sites where high levels of N deposition coincided with both higher mean annual temperature and higher mean annual precipitation. Trends toward foliar P deficiency were thus more marked when high N deposition coincided with climatic conditions favorable to plant production. 3. Atmospheric N deposition was positively correlated with soil-solution NO3-, SO42-, K+, P, and Ca2+ concentrations, the soil-solution NO3-:P ratio, total soil N, and the total soil N:Olsen P ratio, and negatively correlated with soil Olsen P concentration. 4. Despite these nutrient imbalances, during the period studied (1990-2006), N deposition was positively related with Pinus sylvestris absolute basal diameter (BD) growth, although only accounting for the 10% of the total variance. However, neither N deposition nor needle N concentration were related with relative annual BD growth. In contrast, needle P concentration was positively related with both absolute and relative annual BD growth. 5. These results thus indicate a tendency of European P. sylvestris forests to store N in trees and soil in response to N deposition and unveil a trend toward increased nutrient losses in runoff as a consequence of higher soil-solution N concentrations. Overall, the data show increasing ecosystem nutrient imbalances with increasingly limiting roles of P and other nutrients such as K in European P. sylvestris forests, especially in the center of their distribution where higher levels of N deposition are observed. Thus, altho

The presence of competitors and predators as well as plant quality affect which plants an insect feed from. These factors affect food choice through the entire insect life cycle, and is especially important when it comes to nurturing larvae. Females oviposition choice sets the initial stage for larval growth and survival, and it is therefore predicted that there is a strong selection pressure to make them oviposit on the best plants possible. This study looks into the behavior of nutrient driven ovipositing and food choice in the beetles Phratora vitellinae and Lochmaea caprea by offering individuals ten leaves of Salix viminalis, one treated with extra nitrogen in order to increase the nutritional value, and four treated with extra carbon, which should lower the nutritional value. During the choice experiment, only two females of Phratora vitellinae oviposited, making it impossible to draw any conclusion regarding nutrient driven oviposition choice. However, data showed a preference for nitrogen treated leaves and an avoidance of untreated control leaves in almost every case when looking into the largest loss of area for leaves of each treatment. When analyzing the number of leaves of each treatment that is eaten per individual there was a slight preference for nitrogen treated leaves, even though the probability of nitrogen being ranked as most preferred in this case was almost zero. Carbon treated leaves and acetone treated control leaves were equally avoided. For Lochmaea caprea, females fed from a significantly larger numer of leaves than males did (t-test, t=1.86, p=0.0003). An ANOVA showed no significant difference in C:N ratio among leaf treatments (ANOVA, F=9.28E-07, p=0.99). Since plant C:N ratio most likely will increase continuously due to CO2 emissions, the effects an increased carbon concentration in plant tissues has on oviposition and food choice in herbivorous insects is something to look further into. More studies on this subject are therefore need

Enhanced In situ Biodenitrification (EIB) is a capable technology for nitrate removal in subsurface water resources. Optimizing the performance of EIB implies devising an appropriate feeding strategy involving two design parameters: carbon injection frequency and C:N ratio of the organic substrate nitrate mixture. Here we model data on the spatial and temporal evolution of nitrate (up to 1.2 mM), organic carbon (ethanol), and biomass measured during a 342 day-long laboratory column experiment (published in Vidal-Gavilan et al., 2014). Effective porosity was 3% lower and dispersivity had a sevenfold increase at the end of the experiment as compared to those at the beginning. These changes in transport parameters were attributed to the development of a biofilm. A reactive transport model explored the EIB performance in response to daily and weekly feeding strategies. The latter resulted in significant temporal variation in nitrate and ethanol concentrations at the outlet of the column. On the contrary, a daily feeding strategy resulted in quite stable and low concentrations at the outlet and complete denitrification. At intermediate times (six months of experiment), it was possible to reduce the carbon load and consequently the C:N ratio (from 2.5 to 1), partly because biomass decay acted as endogenous carbon to respiration, keeping the denitrification rates, and partly due to the induced dispersivity caused by the well-developed biofilm, resulting in enhancement of mixing between the ethanol and nitrate and the corresponding improvement of denitrification rates. The inclusion of a dual-domain model improved the fit at the last days of the experiment as well as in the tracer test performed at day 342, demonstrating a potential transition to anomalous transport that may be caused by the development of biofilm. This modeling work is a step forward to devising optimal injection conditions and substrate rates to enhance EIB performance by minimizing the overall supply, Sanitary Engineering

Enhanced In situ Biodenitrification (EIB) is a capable technology for nitrate removal in subsurface water resources. Optimizing the performance of EIB implies devising an appropriate feeding strategy involving two design parameters: carbon injection frequency and C:N ratio of the organic substrate nitrate mixture. Here we model data on the spatial and temporal evolution of nitrate (up to 1.2 mM), organic carbon (ethanol), and biomass measured during a 342 day-long laboratory column experiment (published in Vidal-Gavilan et al., 2014). Effective porosity was 3% lower and dispersivity had a sevenfold increase at the end of the experiment as compared to those at the beginning. These changes in transport parameters were attributed to the development of a biofilm. A reactive transport model explored the EIB performance in response to daily and weekly feeding strategies. The latter resulted in significant temporal variation in nitrate and ethanol concentrations at the outlet of the column. On the contrary, a daily feeding strategy resulted in quite stable and low concentrations at the outlet and complete denitrification. At intermediate times (six months of experiment), it was possible to reduce the carbon load and consequently the C:N ratio (from 2.5 to 1), partly because biomass decay acted as endogenous carbon to respiration, keeping the denitrification rates, and partly due to the induced dispersivity caused by the well-developed biofilm, resulting in enhancement of mixing between the ethanol and nitrate and the corresponding improvement of denitrification rates. The inclusion of a dual-domain model improved the fit at the last days of the experiment as well as in the tracer test performed at day 342, demonstrating a potential transition to anomalous transport that may be caused by the development of biofilm. This modeling work is a step forward to devising optimal injection conditions and substrate rates to enhance EIB performance by minimizing the overall supply, Sanitary Engineering

The presence of competitors and predators as well as plant quality affect which plants an insect feed from. These factors affect food choice through the entire insect life cycle, and is especially important when it comes to nurturing larvae. Females oviposition choice sets the initial stage for larval growth and survival, and it is therefore predicted that there is a strong selection pressure to make them oviposit on the best plants possible. This study looks into the behavior of nutrient driven ovipositing and food choice in the beetles Phratora vitellinae and Lochmaea caprea by offering individuals ten leaves of Salix viminalis, one treated with extra nitrogen in order to increase the nutritional value, and four treated with extra carbon, which should lower the nutritional value. During the choice experiment, only two females of Phratora vitellinae oviposited, making it impossible to draw any conclusion regarding nutrient driven oviposition choice. However, data showed a preference for nitrogen treated leaves and an avoidance of untreated control leaves in almost every case when looking into the largest loss of area for leaves of each treatment. When analyzing the number of leaves of each treatment that is eaten per individual there was a slight preference for nitrogen treated leaves, even though the probability of nitrogen being ranked as most preferred in this case was almost zero. Carbon treated leaves and acetone treated control leaves were equally avoided. For Lochmaea caprea, females fed from a significantly larger numer of leaves than males did (t-test, t=1.86, p=0.0003). An ANOVA showed no significant difference in C:N ratio among leaf treatments (ANOVA, F=9.28E-07, p=0.99). Since plant C:N ratio most likely will increase continuously due to CO2 emissions, the effects an increased carbon concentration in plant tissues has on oviposition and food choice in herbivorous insects is something to look further into. More studies on this subject are therefore need

This data set contains mass loss of community roots decomposing in the common plot in the Jena experiment in 2014. The Metadata contains the Dataset ID in the Jena Experiment database and detailed information of column: 'plotcode' is plot ID in the Jena Experiment; 'bag_ID' is the ID for litter bags within each decomposition experiment; 'root_type' is the type of roots in the litter bags where plot coded for community roots, lolium coded for standardized roots; 'site' is the location of where decomposition happened; 'sector' is the subplots in common plot; 'mass_initial' is root mass in the litter bags before buried in the field and handling loss is seduced already; 'mass_remain' is root mass in the litter bags at each retrieval; 'date_in' is the exact dates when the litter bags were buried. In the form of DD-MM-YY; 'date_out' is the exact dates when the litter bags were retrieved. In the form of DD-MM-YY; 'actual_decomptime' is the exact days litter bags were in the field; 'massloss' is actual mass loss =100 - mass_remain/mass_initial*100; 'std_decomptime' is standardized days litter bags were in the field; 'std_massloss' is stadardized mass loss = massloss/actual_decomp.time*std_decomp.time.

The extended phenotype may help us understand how genetically determined trait variation in foundation species can influence associated organisms. Today, there is no existing demonstration of how genetically determined trait variation in Norway spruce (Picea abies) may affect associated organisms in tree canopies. As a majority of all planted Norway spruce seedlings used, in Swedish forestry today, originates from breeding programs it is interesting to know how the genetic material used in these programs may affect associated organisms. For example, according to the growth rate hypothesis the nutritional status of a plant should correspond negatively with tree growth, and the nutritional status of the plant should affect associated organisms. In this study, I aim to evaluate if the genetic origin of Norway spruce affect plant growth and nutritional status of needles (in this case the C:N ratio) and in extension associated communities (abundance of aphids) in the tree canopies. More specifically I will test the following six hypotheses; (1) there is a genetic influence on growth so that breast height diameter (DBH) differ among full-sib families, (2) the growth rate of the trees expressed as their DBH have a significant negative effect on needle C and positive effect on N and consequently negative effect on the C:N ratio, (3) there is a genetic component influencing C:N ratio of the needles so that the ratio differs between full-sib families, (4) growth rate of different full-sib families effect the C:N ratio of needles, (5) the abundance of aphids is influenced by full-sib family and the C:N ratio of needles and (6) growth rate of different full-sib families effect the abundance of aphids. To address these hypotheses twig and insect samples was sampled from Norway spruce trees in 90 two-by-two tree plots from 9 full-sib families. Aphids were determined to species level and needles was analyzed for C and N content with an elemental analyzer. The data on tree growth

Enhanced In situ Biodenitrification (EIB) is a capable technology for nitrate removal in subsurface water resources. Optimizing the performance of EIB implies devising an appropriate feeding strategy involving two design parameters: carbon injection frequency and C:N ratio of the organic substrate nitrate mixture. Here we model data on the spatial and temporal evolution of nitrate (up to 1.2 mM), organic carbon (ethanol), and biomass measured during a 342 day-long laboratory column experiment (published in Vidal-Gavilan et al., 2014). Effective porosity was 3% lower and dispersivity had a sevenfold increase at the end of the experiment as compared to those at the beginning. These changes in transport parameters were attributed to the development of a biofilm. A reactive transport model explored the EIB performance in response to daily and weekly feeding strategies. The latter resulted in significant temporal variation in nitrate and ethanol concentrations at the outlet of the column. On the contrary, a daily feeding strategy resulted in quite stable and low concentrations at the outlet and complete denitrification. At intermediate times (six months of experiment), it was possible to reduce the carbon load and consequently the C:N ratio (from 2.5 to 1), partly because biomass decay acted as endogenous carbon to respiration, keeping the denitrification rates, and partly due to the induced dispersivity caused by the well developed biofilm, resulting in enhancement of mixing between the ethanol and nitrate and the corresponding improvement of denitrification rates. The inclusion of a dual-domain model improved the fit at the last days of the experiment as well as in the tracer test performed at day 342, demonstrating a potential transition to anomalous transport that may be caused by the development of biofilm. This modeling work is a step forward to devising optimal injection conditions and substrate rates to enhance EIB performance by minimizing the overall supply of, Peer Reviewed, Postprint (author's final draft)

Bottom sediment is an archive of the historical changes in a lake and its catchment. This thesis is apalaeoenvironmental reconstruction of catchment processes in Bolgoda Lake situated in western SriLanka. We studied a sediment core retrieved from this lake. In our study, we focus on multiplephysical and chemical proxies: grain-size, loss-on-ignition, total organic carbon content, C:N ratio,and δ13C stored in the organic matter. The aim of this study is to contribute to a better understandingof the palaeoenvironmental conditions in the region and allow a comparison between this site andothers.In the deepest part of the core, we see an overall high sand content, which indicates a period ofhigher discharge into the lake compared to what the other core parts indicate. This is probably aresult of higher precipitation. This is followed by a decline in C:N and a rise in TOC in the second partwhich indicates an increase of primary production in the lake. In the third part we again see a shift inthe C:N indicating a source change back to more terrestrial runoff. The increase in TOC and LOIvalues together with decrease in C:N ratio and a steady increase in δ13C indicate an increase inlacustrine productivity in the upper part of the core.By reconstructing the palaeoenvironmental history in Bolgoda Lake we can conclude that it isprobable that some other factor than diagenetic change affects the lake. Our results indicate thatthese changes most likely are due to more wet periods and anthropogenic activity, mainly throughland use changes.

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements., At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements., At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements., At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements., At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted

Mysid shrimps (Mysidacea, Crustacea) are efficient zooplanktivores in both marine and freshwater systems as well as lipid rich prey for many species of fish. Although some efforts have been made to study the role of mysids in the Baltic Sea, very few studies have been carried out in recent time and there are still knowledge gaps regarding various aspects of mysid ecology. This thesis aims to explore some of these gaps by covering a mixture of topics. Using multifrequency hydroacoustics we explored the possibility to separate mysids from fish echoes and successfully established a promising and effective method for obtaining mysid abundance/biomass estimates (paper I). An investigation of the current mysid community in a coastal area of the northern Baltic proper (paper II) demonstrated that the formerly dominant, pelagic mysid Mysis mixta had decreased substantially (~50%) in favor for phytoplanktivorous, juvenile Neomysis integer and Mysis relicta sp. By examining different aspects of mysid behavior, we studied the vertical size distribution of mysids in the field and found that size increased with depth/declining light, irrespective of temperature; indicating that their vertical size distribution primarily is a response to predation (paper II). In paper III, a combination of ecological and genetic markers was used to investigate intraspecific differences in migratory tendency. Both marker types indicated that some part of the Mysis salemaai population is sedentary on the bottom and that this strategy is a phenotypically plastic but persistent trait, analogous to the partial migrations seen in many birds and fishes. In paper IV a temperature and weight specific respiration model was developed for the littoral Praunus flexuosus. Routine respiration was moreover elevated by post-prandial effects (specific dynamic action) for longer times than previously suggested. Consequently, ignoring such effects could significantly bias respiration measurements., At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Accepted; Paper 3: Submitted; Paper 4: Accepted

Rates of oxygen consumption (R) and ammonia excretion (E) of 29 species of small teleost fishes, which weighed between 1 and 400 mg dry mass (DM), from inshore waters of the Great Barrier Reef were determined at in situ temperatures (25 to 30°C). Regression analyses revealed that R (6.7 to 1296 µl O2 ind.–1 h–1) and E (0.28 to 64.2 µg NH4-N ind.–1 h–1) were correlated with body mass, but the ratio of R to E ( oxygen to nitrogen ratio; 17 to 104 by atoms), was not. Water content of fish bodies ranged from 66.0 to 81.4% of wet mass (WM), and ash content from 11.9 to 28.6% of DM. Total carbon (C) and total nitrogen (N) composition varied from 36.2 to 44.4% and from 8.3 to 12.8% of DM, respectively, resulting in C:N ratios of 3.1 to 4.7. Fractions of inorganic C and N were small (0.04 to 0.33% and 0.01 to 0.15% of DM, respectively). Combining R and E data with those of body C and N composition, daily metabolic losses were estimated to be 4.3 to 18.6% for body C and 0.8 to 9.1% for body N. The present R–body mass relationships were compared with the 3 published predictive models for fishes to explore the best fit model. On a body mass basis expressed by N, values for R were consistent with the model for epipelagic zooplankton, but values for E were 30% lower, suggesting somewhat reduced E relative to R in fishes as compared with zooplankton. Three out of the 29 fishes exhibited markedly high metabolic O:N ratios together with high body C:N ratios, which was interpreted as an adaptation to N-limited detritus nutrition.

Rates of oxygen consumption (R) and ammonia excretion (E) of 29 species of small teleost fishes, which weighed between 1 and 400 mg dry mass (DM), from inshore waters of the Great Barrier Reef were determined at in situ temperatures (25 to 30°C). Regression analyses revealed that R (6.7 to 1296 µl O2 ind.–1 h–1) and E (0.28 to 64.2 µg NH4-N ind.–1 h–1) were correlated with body mass, but the ratio of R to E ( oxygen to nitrogen ratio; 17 to 104 by atoms), was not. Water content of fish bodies ranged from 66.0 to 81.4% of wet mass (WM), and ash content from 11.9 to 28.6% of DM. Total carbon (C) and total nitrogen (N) composition varied from 36.2 to 44.4% and from 8.3 to 12.8% of DM, respectively, resulting in C:N ratios of 3.1 to 4.7. Fractions of inorganic C and N were small (0.04 to 0.33% and 0.01 to 0.15% of DM, respectively). Combining R and E data with those of body C and N composition, daily metabolic losses were estimated to be 4.3 to 18.6% for body C and 0.8 to 9.1% for body N. The present R–body mass relationships were compared with the 3 published predictive models for fishes to explore the best fit model. On a body mass basis expressed by N, values for R were consistent with the model for epipelagic zooplankton, but values for E were 30% lower, suggesting somewhat reduced E relative to R in fishes as compared with zooplankton. Three out of the 29 fishes exhibited markedly high metabolic O:N ratios together with high body C:N ratios, which was interpreted as an adaptation to N-limited detritus nutrition.

Rates of oxygen consumption (R) and ammonia excretion (E) of 29 species of small teleost fishes, which weighed between 1 and 400 mg dry mass (DM), from inshore waters of the Great Barrier Reef were determined at in situ temperatures (25 to 30°C). Regression analyses revealed that R (6.7 to 1296 µl O2 ind.–1 h–1) and E (0.28 to 64.2 µg NH4-N ind.–1 h–1) were correlated with body mass, but the ratio of R to E ( oxygen to nitrogen ratio; 17 to 104 by atoms), was not. Water content of fish bodies ranged from 66.0 to 81.4% of wet mass (WM), and ash content from 11.9 to 28.6% of DM. Total carbon (C) and total nitrogen (N) composition varied from 36.2 to 44.4% and from 8.3 to 12.8% of DM, respectively, resulting in C:N ratios of 3.1 to 4.7. Fractions of inorganic C and N were small (0.04 to 0.33% and 0.01 to 0.15% of DM, respectively). Combining R and E data with those of body C and N composition, daily metabolic losses were estimated to be 4.3 to 18.6% for body C and 0.8 to 9.1% for body N. The present R–body mass relationships were compared with the 3 published predictive models for fishes to explore the best fit model. On a body mass basis expressed by N, values for R were consistent with the model for epipelagic zooplankton, but values for E were 30% lower, suggesting somewhat reduced E relative to R in fishes as compared with zooplankton. Three out of the 29 fishes exhibited markedly high metabolic O:N ratios together with high body C:N ratios, which was interpreted as an adaptation to N-limited detritus nutrition.

Interpolation of point measurements using geostatistical techniques such as kriging can be used to estimate values at non-sampled locations in space. Traditional geostatistics are based on the spatial autocorrelation concept that nearby things are more related than distant things. In this study, additional information was used to modify the traditional Euclidean concept of distance into an adjusted distance metric that incorporates similarity in terms of quantifiable landscape characteristics such as topography or land use. This new approach was tested by interpolating soil moisture content, pH and carbon-tonitrogen (C:N) ratio measured in both the mineral and the organic soil layers at a field site in central Sweden. Semivariograms were created using both the traditional distance metrics and the proposed adjusted distance metrics to carry out ordinary kriging (OK) interpolations between sampling points. In addition, kriging with external drift (KED) was used to interpolate soil properties to evaluate the ability of the adjusted distance metric to incorporate secondary data into interpolations. The new adjusted distance metric typically lowered the nugget associated with the semivariogram, thereby better representing small-scale variability in the measured data compared to semivariograms based on the traditional distance metric. The pattern of the resulting kriging interpolations using KED and OK based on the adjusted distance metric were similar because they represented secondary data and, thus, enhanced small-scale variability compared to traditional distance OK. This created interpolations that agreed better with what is expected for the real-world spatial variation of the measured properties. Based on cross-validation error, OK interpolations using the adjusted distance metric better fit observed data than either OK interpolations using traditional distance or KED. © 2010 Taylor & Francis.

Hypolimnetic oxygen content in lentic ecosystems has traditionally been modeled as a function of variables measured at the epilimnion, or that are supposed to drive epilimnetic processes, like total phosphorus load. However, in man-made reservoirs the river inflow can plunge into deep layers, directly linking the hypolimnion with the surrounding watershed. In these circumstances, organic matter carried by the river can influence the hypolimnetic oxygen content without important intervention of epilimnetic processes. Taking long-term data from two reservoirs in Spain, we applied an empirical regression approach to show that the dissolved organic matter carried by the river is the main driver shaping the hypolimnetic oxygen content. By contrast, typical variables commonly included in the modeling of the oxygen content in the hypolimnion (nutrient concentrations, chlorophyll a, and dissolved organic carbon measured in the water column) did not show any significant correlation. Interpretations from this regression approach were supported by a comparison between the monthly oxygen consumption in the hypolimnion and the monthly dissolved organic carbon load from the river inflow. We also revisited the prediction of the year-to-year variability of the Nürnberg's anoxic factor in four reservoirs from Spain and the USA, explicitly including the allochthonous sources in the equations. These sources were significant predictors of the anoxic factor, especially in those systems subject to relatively high human impact. Thus, effects of allochthonous dissolved organic carbon should always be considered in empirical modeling and management of reservoir hypolimnetic processes related to oxygen content (for example, anoxia, nutrient internal loading, or phosphorus cycle resilience). © 2008 Springer Science+Business Media, LLC.

The mechanisms behind the 13C enrichment of organic matter with increasing soil depth in forests are unclear. To determine if 13C discrimination during respiration could contribute to this pattern, we compared d13C signatures of respired CO2 from sieved mineral soil, litter layer and litterfall with measurements of d13C and d15N of mineral soil, litter layer, litterfall, roots and fungal mycelia sampled from a 68-year-old Norway spruce forest stand planted on previously cultivated land. Because the land was subjected to ploughing before establishment of the forest stand, shifts in d13C in the top 20 cm reflect processes that have been active since the beginning of the reforestation process. As 13C-depleted organic matter accumulated in the upper soil, a 1.0 o/oo d13C gradient from -28.5 o/oo in the litter layer to -27.6 o/oo at a depth of 2-6 cm was formed. This can be explained by the 1 o/oo drop in d13C of atmospheric CO2 since the beginning of reforestation together with the mixing of new C (forest) and old C (farmland). However, the isotopic change of the atmospheric CO2 explains only a portion of the additional 1.0 & increase in d13C below a depth of 20 cm. The d13C of the respired CO2 was similar to that of the organic matter in the upper soil layers but became increasingly 13C enriched with depth, up to 2.5 o/oo relative to the organic matter. We hypothesise that this 13C enrichment of the CO2 as well as the residual increase in d13C of the organic matter below a soil depth of 20 cm results from the increased contribution of 13C-enriched microbially derived C with depth. Our results suggest that 13C discrimination during microbial respiration does not contribute to the 13C enrichment of organic matter in soils. We therefore recommend that these results should be taken into consideration when natural variations in d13C of respired CO2 are used to separate different components of soil respiration or ecosystem respiration.

Rendzina is a widespread soil type in Serbia that can be found in several stages of evolutionary development and put to different land uses. Our objective was to investigate the effect of decarbonation of rendzina soils in Serbia and several land use variants on humus content and its enrichment in nitrogen. Humus content is mostly high, and rarely medium, in the A horizon of calcaric forest rendzinas; medium or high under grassland, and very low under arable land. In non-calcaric forest rendzinas, humus content in horizon A is medium or low; under grassland it is low and very low, and under arable land again low and very low. Rendzinas are predominantly rich and very rich in total nitrogen in the uppermost layer of horizon A, and medium or well supplied in the layer below it. Enrichment of humus in nitrogen, shown as the C:N ratio, is mostly medium, and rarely low. Decarbonation was caused by decreasing humus content and total nitrogen in soil, while the enrichment of humus in nitrogen (C:N ratio) showed no significant change. Different land uses were found to have significant effect on decreasing humus and total nitrogen contents in rendzinas under grassland, and especially arable land, compared to forest rendzinas, while humus enrichment in nitrogen was significantly higher in rendzinas underlying grassland than forest. ., Rendzina je veoma rasprostranjen tip zemljišta u Srbiji u području brdsko-planinskog reljefa, nalazi se u više evolucionih stadijuma razvoja i koristi se na različite načine, odnosno, nalazi se pod različitim biljnim pokrivačima. Cilj našeg rada je zato bio ispitivanje uticaja procesa izluživanja i različitog načina korišćenja zemljišta tipa rendzina u Srbiji na sadržaj humusa i njegovu obezbeđenost azotom. Sadržaj ukupnog C u ispitivanim rendzinama Srbije varira od 1.15 do 6.25%, a u proseku iznosi 3.25%. Sadržaj humusa u A horizontu karbonatnih šumskih rendzina je uglavnom visok, ređe srednji; pod travnjacima srednji ili visok, a pod njivama veoma nizak. U izluženim šumskim rendzinama sadržaj humusa u A horizontu je srednji ili nizak; pod travnjacima nizak i veoma nizak, a u njivskim, takođe, nizak i veoma nizak. Sadržaj ukupnog azota varira u širokom intervalu, od 0,123 do 0.570%, a u proseku iznosi 0.317%; stoga su rendzine pretežno bogato i veoma bogato obezbeđene ukupnim azotom u površinskom delu A horiznonta, a u potpovršinskom obezbeđene su srednje ili dobro. Obezbeđenost humusa azotom, izražena preko odnosa C:N, uglavnom je srednja, a ređe niska. Odnos C:N kreće se od 8.09 do 16.54, a u proseku iznosi 10.09. Procesi izluživanja (ispiranje CaCO3, niži pH i stepen zasićenosti bazama) u zemljištima tipa rendzina u Srbiji uslovili su smanjenje sadržaja humusa i ukupnog azota, pri čemu se obezbeđenost humusa azotom (odnos C:N) nije značajno promenila. Razlike u načinu korišćenja zemljišta (primena ili odsustvo obrade i razlike u količini i kvalitetu biljnih ostataka) statistički su značajno uticale na smanjenje sadržaja humusa i ukupnog azota u rendzinama pod travnjacima i naročito njivama u poređenju sa šumskim rendzinama, dok je obezbeđenost humusa azotom značajno veća u travnjačkim u poređenju sa šumskim rendzinama. .

Rendzina is a widespread soil type in Serbia that can be found in several stages of evolutionary development and put to different land uses. Our objective was to investigate the effect of decarbonation of rendzina soils in Serbia and several land use variants on humus content and its enrichment in nitrogen. Humus content is mostly high, and rarely medium, in the A horizon of calcaric forest rendzinas; medium or high under grassland, and very low under arable land. In non-calcaric forest rendzinas, humus content in horizon A is medium or low; under grassland it is low and very low, and under arable land again low and very low. Rendzinas are predominantly rich and very rich in total nitrogen in the uppermost layer of horizon A, and medium or well supplied in the layer below it. Enrichment of humus in nitrogen, shown as the C:N ratio, is mostly medium, and rarely low. Decarbonation was caused by decreasing humus content and total nitrogen in soil, while the enrichment of humus in nitrogen (C:N ratio) showed no significant change. Different land uses were found to have significant effect on decreasing humus and total nitrogen contents in rendzinas under grassland, and especially arable land, compared to forest rendzinas, while humus enrichment in nitrogen was significantly higher in rendzinas underlying grassland than forest. ., Rendzina je veoma rasprostranjen tip zemljišta u Srbiji u području brdsko-planinskog reljefa, nalazi se u više evolucionih stadijuma razvoja i koristi se na različite načine, odnosno, nalazi se pod različitim biljnim pokrivačima. Cilj našeg rada je zato bio ispitivanje uticaja procesa izluživanja i različitog načina korišćenja zemljišta tipa rendzina u Srbiji na sadržaj humusa i njegovu obezbeđenost azotom. Sadržaj ukupnog C u ispitivanim rendzinama Srbije varira od 1.15 do 6.25%, a u proseku iznosi 3.25%. Sadržaj humusa u A horizontu karbonatnih šumskih rendzina je uglavnom visok, ređe srednji; pod travnjacima srednji ili visok, a pod njivama veoma nizak. U izluženim šumskim rendzinama sadržaj humusa u A horizontu je srednji ili nizak; pod travnjacima nizak i veoma nizak, a u njivskim, takođe, nizak i veoma nizak. Sadržaj ukupnog azota varira u širokom intervalu, od 0,123 do 0.570%, a u proseku iznosi 0.317%; stoga su rendzine pretežno bogato i veoma bogato obezbeđene ukupnim azotom u površinskom delu A horiznonta, a u potpovršinskom obezbeđene su srednje ili dobro. Obezbeđenost humusa azotom, izražena preko odnosa C:N, uglavnom je srednja, a ređe niska. Odnos C:N kreće se od 8.09 do 16.54, a u proseku iznosi 10.09. Procesi izluživanja (ispiranje CaCO3, niži pH i stepen zasićenosti bazama) u zemljištima tipa rendzina u Srbiji uslovili su smanjenje sadržaja humusa i ukupnog azota, pri čemu se obezbeđenost humusa azotom (odnos C:N) nije značajno promenila. Razlike u načinu korišćenja zemljišta (primena ili odsustvo obrade i razlike u količini i kvalitetu biljnih ostataka) statistički su značajno uticale na smanjenje sadržaja humusa i ukupnog azota u rendzinama pod travnjacima i naročito njivama u poređenju sa šumskim rendzinama, dok je obezbeđenost humusa azotom značajno veća u travnjačkim u poređenju sa šumskim rendzinama. .

Nitrogen losses from cattle feedlots are a concern due to loss of valuable N and enrichment of the atmospheric N pool. Nutritional methods to decrease losses would have economic and environmental benefit. One method to decrease N losses is by increasing carbon on the pen surface. From a management perspective, feeding a diet that will increase carbon may be the most cost effective. Therefore, three experiments evaluated feeding corn bran (less digestible than corn) at either 0, 15, or 30% of the diet. The 15 and 30% bran diets increase organic matter (carbon) excretion by approximately 0.5 and 1.0 kg/steer/d, respectively. Compared with no bran, feeding 15 and 30% decreased feed efficiency by 7.8 and 10.4%, respectively. Nutrient balance was assessed for two trials from October through May and one trial from June to September. During the trials from October to May, N losses were decreased by 14.5 and 20.7% for the 15 and 30% bran diets compared with no bran. Feeding 15 or 30% bran did not influence N losses in the experiment from June to September. Increasing the carbon: nitrogen ratio of manure prior to cleaning open-dirt feedlots has variable results depending on time of year.