Assimilation of inorganic nutrients from salmon (Salmo salar) farming by the macroalgae (Saccharina latissima) in an exposed coastal environment: implications for integrated multi-trophic aquaculture

This paper investigated the assimilation of dissolved inorganic nitrogen (DIN) in Saccharina latissima in proximity to salmon cages in coastal waters. The bioassays were performed on plants from three stations located in the vicinity of a salmon farm (Salmo salar) in exposed waters at Tristein (63° 52′ N, 9° 37′ E) in Central Norway. The growth, the C and N content, and the nitrogen isotope ratios (δ¹⁵N) of S. latissima were monitored over 1 year. The DIN concentrations in seawater were higher at the salmon farm stations than at the reference station during the winter, and the N/P ratio at the salmon farm stations was higher from September to January and in June. S. latissima at the salmon farm stations grew faster than at the reference station. The length of S. latissima increased by 50 % when integrated with the salmon farm compared to the reference station. The N content of S. latissima was positively correlated to the DIN concentration in seawater (p?<?0.05), but the increased N supply from salmon did not result in N accumulation in S. latissima at the salmon farm station because of the dilution by a higher growth rate. The δ¹⁵N in S. latissima was higher at the salmon farm station from April to June and changed in the direction of the δ¹⁵N signature in urine. This indicated that N in S. latissima at the salmon farm station partly originated from the salmon. One hectare of S. latissima may absorb 0.8～1.2 t N during one growth season. Large-scale cultivation of S. latissima should be considered to mitigate the environmental effects of DIN wastes from salmon farms.     

Effect of supplementing sheep diets with macroalgae species on in vivo nutrient digestibility,rumen fermentation and blood amino acid profile

In this study, a brown macroalgae species, Saccharina latissima, processed to increase its protein concentration, and a red macroalgae species, Porphyra spp., were used to evaluate their in vivo digestibility, rumen fermentation and blood amino acid concentrations. Four castrated rams were used, whose diets were supplemented with a protein-rich fraction of S. latissima, a commercial Porphyra spp. and soybean meal (SBM). Our results show that the protein digestibility of a diet with S. latissima extract was lower (0.55) than those with Porphyra spp. (0.64) and SBM (0.66). In spite of the higher nitrogen (N) intake of diets containing Porphyra spp. and SBM (20.9 and 19.8 g N/day, respectively) than that with S. latissima (18.6 g N/day), the ratio of N excreted in faeces to total N intake was significantly higher in the diet with S. latissima than those with Porphyra spp. and SBM. This reflects that the utilization of protein in S. latissima was impaired, possibly due to reduced microbial activity. The latter statement is corroborated by lower volatile fatty acid composition (25.6, 54.8 and 100 mmol/l for S. latissima, Porphyra spp. and SBM, respectively) and a non-significant tendency for lower ammonia concentration observed in diets with S. latissima and Porphyra spp. compared to SBM. It is important to note that the S. latissima used in this trial was rinsed during processing to remove salt. This process potentially also removes other water-soluble compounds, such as free amino acids, and may have increased the relative fraction of protein resistant to rumen degradation and intestinal absorption. Furthermore, the phlorotannins present in macroalgae may have formed complexes with protein and fibre, further limiting their degradability in rumen and absorption in small intestines. We recommend that further studies explore the extent to which processing of macroalgae affects its nutritive properties and rumen degradability, in addition to studies to measure the intestinal absorption of these macroalgae species.     

Patterns of Saccharina latissima Recruitment

The lack of recovery in Norwegian populations of the kelp Saccharina latissima (Linnaeus) C. E. Lane, C. Mayes, Druehl & G. W. Saunders after a large-scale disturbance that occurred sometime between the late 1990s and early 2000s has raised considerable concerns. Kelp forests are areas of high production that serve as habitats for numerous species, and their continued absence may represent the loss of an entire ecosystem. Some S. latissima populations remain as scattered patches within the affected areas, but today, most of the areas are completely devoid of kelp. The question is if natural recolonization by kelp and the reestablishment of the associated ecosystem is possible. Previous studies indicate that a high degree of reproductive synchrony in macrophytes has a positive effect on their potential for dispersal and on the connectivity between populations, but little is known about the patterns of recruitment in Norwegian S. latissima. More is, however, known about the development of fertile tissue (sori) on adult individuals, which is easily observed. The present study investigated the degree of coupling between the appearance of sori and the recruitment on clean artificial substrate beneath adult specimens. The pattern of recruitment was linked to the retreat of visible sori (i.e. spore release) and a seasonal component unrelated to the fertility of the adults. The formation and the retreat of visible sori are processes that seem synchronized along the south coast of Norway, and the link between sori development and recruitment may therefore suggest that the potential for S. latissima dispersal is relatively large. These results support the notion that the production and dispersal of viable spores is unlikely to be the bottleneck preventing recolonization in the south of Norway, but studies over larger temporal and spatial scales are still needed to confirm this hypothesis.     

Biomass yield and morphological features of the seaweed Saccharina latissima cultivated at two different sites in a coastal bay in the Atlantic coast of Spain

The kelp Saccharina latissima is an economically important edible seaweed with great potential for use in other applications. The goal of this study was to identify locations in a coastal bay with better conditions for commercial cultivation of this species. We compared the biomass yield and morphological features of S. latissima cultivated at two locations in a bay of Galicia (northwest Spain): in an external moderately exposed site and in an internal sheltered site. Biomass yield was significantly higher at the moderately exposed site than at the sheltered site (16 fresh kg vs. 12 fresh kg per linear meter of rope). Fronds were significantly larger at the moderately exposed site compared to that at the sheltered site. However, the “substantiality value” (around 40 mg cm^?2), which is an index used to assess blade quality for human consumption, did not differ significantly between the two locations. The effect of light exposure and water velocity seemed to be the most important environmental factors that explain the differences in the results obtained at both culture sites. In summary, both the moderately exposed site and the sheltered site were suitable for cultivation of S. latissima, as indicated by the high yields and similar blade quality obtained at both locations.     

Seasonal and tidal variability of environmental carbon related physico-chemical variables and inorganic C acquisition in Gracilariopsis longissima and Enteromorpha intestinalis from Los Toruños salt marsh (Cádiz Bay, Spain)

The seasonal and tidal variability of inorganic C acquisition mechanisms, photosynthesis, internal composition and growth were studied in two co-occurring macroalgae in Los Toruños salt marsh (Cádiz Bay), Gracilariopsis longissima and Enteromorpha intestinalis. This variability was monitored together with physico-chemical variables affecting carbon availability, photosynthesis, and growth. The environmental variables, such as light, temperature, pH, salinity, oxygen, alkalinity, dissolved inorganic carbon (DIC) and CO₂, displayed not only an expected seasonal cycle but also a daily (tidal) variability, with abrupt and rapid changes influenced by biological activities, physical variables, tidal state and tidal timing. In contrast to environmental variables, photosynthesis, pigments and C:N composition were affected by seasonal changes but not by tidal regimes, as organisms integrated these short-term fluctuations in physico-chemical variables. Photosynthesis, pigments and internal N composition were maximal in autumn and minimal in summer for both species. Growth showed a seasonal trend, displaying a summer drop with negative values. This response can be the result of extreme values of environmental variables (temperature, light, pH, nutrients, and the shortage of DIC) in summer, in comparison with higher growth rates in September onwards. The use of inhibitors of carbon acquisition in situ at normal DIC concentrations (2.2. mM) revealed species-dependent differences. While the external carbonic anhydrase (CA) activity showed a constitutive character in G. longissima, it showed little effect in E. intestinalis, which relies on internal CA activity. The 4, 4′-diisothiocyanatostilbene-2,2′-disulfonate (DIDS)-sensitive bicarbonate transport in G. longissima was effective in winter. In contrast, DIDS stimulated photosynthesis in summer, and relieved AZ inhibition. This response could suggest a stimulation of a H⁺ extrusion mediated-CO₂ transport in periods of low CO₂ availability.     

Seasonal growth patterns of Saccharina latissima (Phaeophyceae,Ochrophyta) in a glacially‐influenced subarctic estuary

Global climate warming is exacerbating the melting of glaciers in Arctic and subarctic nearshore regions. Glacial discharge causes increases in sedimentation, abrasion of organisms, and sand/silt cover along with lowered light intensity, salinity, nitrate and hard substrate cover. These effects can have deleterious consequences on foundation species, such as the kelps that provide important habitat structure and support tightly‐linked food webs. The purpose of this study was to determine if the kelp, Saccharina latissima, from a glacially‐influenced and an oceanic shore in a subarctic Alaskan estuary exhibits differing seasonal growth patterns in response to its environment. Reciprocal in situ shore transplant studies examined seasonal patterns in growth, physiological competence (as maximum quantum yield), morphology and storage product levels (mannitol) of S. latissima. In situ growth was seasonally different at the two shore locations, with a shorter growing season at the glacially‐influenced shore. During the glacial melt season, the thalli at the two shore locations were morphologically distinct. Mannitol levels were typically higher in thalli from the oceanic site, with generally low mannitol levels at the end and the beginning of the growing season on both shores. Maximum quantum yield was consistently high (≥0.7) at both shore sites and did not vary seasonally. Growth rates of glacially‐influenced transplants to the oceanic shore suggest that the glacially‐influenced population has a different seasonal growth pattern from that of the oceanic shore site, which seems to be genetically fixed or based on differences in gene expression. It appears that S. latissima is a highly resilient species, partly due to high phenotypic plasticity, which may have led to genetic fixation under persistent glacial conditions.     

Development of Saccharina latissima (Phaeophyceae) kelp hatcheries with year-round production of zoospores and juvenile sporophytes on culture ropes for kelp aquaculture

Saccharina latissima is attractive for industrial cultivation for different usages, such as biofuels, feed supplements, and derivation of chemicals. A continuous supply of kelp sporelings throughout the year may ensure a year-round production of kelp juveniles on ropes. In this study, induction of sporangial areas (sorus portions) on the blade of S. latissima was performed throughout the year at three locations: Trondheim (Norway), Grenaa (Denmark), and Sylt island (Germany). The results indicate that a year-round sorus induction in S. latissima is possible and that this induction is controlled by applying short-day treatment of adult sporophytes throughout the year and by the removal of the basal blade meristem. The artificially induced and released zoospores formed viable sporelings at all seasons, but cultivation in the sea in Norway was successful only during autumn, winter, and spring, while the growth conditions were poor during the summer. The results are important for industrial scale-up and continuous production of kelp biomass.     

Temperature acclimation and heat tolerance of photosynthesis in Norwegian Saccharina latissima (Laminariales,Phaeophyceae)

Kelps, seaweeds and seagrasses provide important ecosystem services in coastal areas, and loss of these macrophytes is a global concern. Recent surveys have documented severe declines in populations of the dominant kelp species, Saccharina latissima, along the south coast of Norway. S. latissima is a cold‐temperate species, and increasing seawater temperature has been suggested as one of the major causes of the decline. Several studies have shown that S. latissima can acclimate to a wide range of temperatures. However, local adaptations may render the extrapolation of existing results inappropriate. We investigated the potential for thermal acclimation and heat tolerance in S. latissima collected from three locations along the south coast of Norway. Plants were kept in laboratory cultures at three different growth temperatures (10, 15, and 20°C) for 4–6 weeks, after which their photosynthetic performance, fluorescence parameters, and pigment concentrations were measured. S. latissima obtained almost identical photosynthetic characteristics when grown at 10 and 15°C, indicating thermal acclimation at these temperatures. In contrast, plants grown at 20°C suffered substantial tissue deterioration, and showed reduced net photosynthetic capacity caused by a combination of elevated respiration and reduced gross photosynthesis due to lowered pigment concentrations, altered pigment composition, and reduced functionality of Photo‐system II. Our results support the hypothesis that extraordinarily high temperatures, as observed in 1997, 2002, and 2006, may have initiated the declines in S. latissima populations along the south coast of Norway. However, observations of high mortality in years with low summer temperatures suggest that reduced population resilience or other factors may have contributed to the losses.     

Seasonality and resource availability control bacterial and archaeal communities in soils of a temperate beech forest

It was hypothesized that seasonality and resource availability altered through tree girdling were major determinants of the phylogenetic composition of the archaeal and bacterial community in a temperate beech forest soil. During a 2-year field experiment, involving girdling of beech trees to intercept the transfer of easily available carbon (C) from the canopy to roots, members of the dominant phylogenetic microbial phyla residing in top soils under girdled versus untreated control trees were monitored at bimonthly intervals through 16S rRNA gene-based terminal restriction fragment length polymorphism profiling and quantitative PCR analysis. Effects on nitrifying and denitrifying groups were assessed by measuring the abundances of nirS and nosZ genes as well as bacterial and archaeal amoA genes. Seasonal dynamics displayed by key phylogenetic and nitrogen (N) cycling functional groups were found to be tightly coupled with seasonal alterations in labile C and N pools as well as with variation in soil temperature and soil moisture. In particular, archaea and acidobacteria were highly responsive to soil nutritional and soil climatic changes associated with seasonality, indicating their high metabolic versatility and capability to adapt to environmental changes. For these phyla, significant interrelations with soil chemical and microbial process data were found suggesting their potential, but poorly described contribution to nitrification or denitrification in temperate forest soils. In conclusion, our extensive approach allowed us to get novel insights into effects of seasonality and resource availability on the microbial community, in particular on hitherto poorly studied bacterial phyla and functional groups.     

Differential δC and δN signatures among scallop tissues: implications for ecology and physiology

There have been several studies where the isotopic composition of organisms has been determined seasonally, but fewer have examined separate organs. In this context, separate organs (e.g. gonad, digestive gland and muscle) of a suspension-feeder, the scallop Pecten maximus, were used to assess seasonal changes of both stable isotopes and biochemical components. Our study used multiple indicators [stable carbon and nitrogen isotope ratios, biochemical components and seston chlorophyll-a (chl a)] to track nutritive activity and energy allocation in P. maximus from the Bay of Brest (France). In addition to seasonal variation in the isotopic composition of P. maximus tissues, we found strong differences in the mean isotopic signatures of different organs. This has serious implications for interpretation of animal diets and potential use in animal physiology. Furthermore, we present evidence that seasonal variations of metabolism will cause changes in the isotopic composition not related to changes in the diet. Interpretation of isotopic data may require consideration of values from several separate organs. Finally, δ¹⁵N appears powerful to track metabolite fates in the scallop P. maximus.     

Assimilatory Sulfur Metabolism in Marine Microorganisms: Sulfur Metabolism, Protein Synthesis, and Growth of Alteromonas luteo-violaceus and Pseudomonas halodurans During Perturbed Batch Growth

The antibiotic protein synthesis inhibitor chloramphenicol specifically blocked the incorporation of [³⁵S]sulfate into the residue protein of two marine bacteria, Pseudomonas halodurans and Alteromonas luteo-violaceus. Simultaneous inhibition of total protein synthesis occurred, but incorporation of ³⁵S into low-molecular-weight organic compounds continued. A. luteo-violaceus rapidly autolyzed, with similar reduction in cell counts, total culture protein and cellular sulfur, whereas P. halodurans remained viable. Treatment with chloramphenicol, growth during nitrogen and carbon limitation, and the carbon and energy sources used for growth did not alter the sulfur content of P. halodurans protein. The mean value (1.09%, by weight), representing a wide variety of environmentally relevant growth conditions, was in agreement with model protein composition. The variability of cellular composition of P. halodurans and A. luteo-violaceus is discussed with respect to the measurement of bacterial growth in natural environments. Total carbon and nitrogen per cell varied greatly (coefficient of variation, ca. 100%) depending on growth conditions. Variation in total sulfur and protein per cell was much less (coefficient of variation, <50%), but the least variation was found for sulfate incorporation into residue protein (coefficient of variation, ca. 15%). Thus, sulfate incorporation into residue protein can be used as an accurate measurement of de novo protein synthesis in these bacteria.     

Modulation of physiological performance by temperature and salinity in the sugar kelp Saccharina latissima

The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species.     

Genetic diversity of Saccharina latissima (Phaeophyceae) along a salinity gradient in the North Sea–Baltic Sea transition zone

The North Sea–Baltic Sea transition zone constitutes a boundary area for the kelp species Saccharina latissima due to a strong salinity gradient operating in the area. Furthermore, the existence of S. latissima there, along Danish waters, is fairly patchy as hard bottom is scarce. In this study, patterns of genetic diversity of S. latissima populations were evaluated along the salinity gradient area of Danish waters (here designated brackish) and were compared to reference sites (here designated marine) outside the gradient area, using microsatellite markers. The results showed that the S. latissima populations were structured into two clusters corresponding to brackish versus marine sites, and that gene flow was reduced both between clusters and between populations within clusters. In addition, results provided empirical evidence that marginal populations of S. latissima in the salinity gradient area exhibited a distinct genetic structure when compared to marine ones. Brackish populations were less diverse, more related, and showed increased differentiation over distance compared to marine populations. The isolation of the brackish S. latissima populations within the salinity gradient area of Danish waters in conjunction with their general low genetic diversity makes these populations vulnerable to ongoing environmental and climate change, predicted to result in declining salinity in the Baltic Sea area that may alter the future distribution and performance of S. latissima in the area.     

Comparative mycelial and spore yield by Trichoderma viride in batch and fed-batch cultures

The effects of cultural parameters such as carbon and nitrogen source and environmental factors including temperature and pH were investigated on spore and mycelial yield of Trichoderma viride, which has potential as a biocontrol agent against species of Fusarium in batch culture and fed-batch culture where there was limiting nutrient. The results obtained indicated that growth and sporulation of T. viride were greatly influenced by various carbon and nitrogen sources, and by environmental factors such as pH and temperature. Mannitol, wheat bran and rice bran as sole carbon sources appear to stimulate high mycelial growth and spore yield in fed-batch culture. Growth and sporulation were also favoured by NaNO₃, peptone and NH₄SO₄ as the nitrogen sources in fed-batch and batch cultures_. Maximum growth and sporulation was between pH 4.5 and 6.0. Temperatures between 30 and 37 °C were good for mycelium growth of T. viride while temperatures between 30 to 45 °C were good for sporulation. The amount of spore and mycelium produced and the time required for attainment of maximum spore yield increased with increasing carbon and nitrogen source in batch culture. The final spore yield obtained in fed-batch culture was two times higher than the apparent spore-carrying capacity of batch culture. These results show that T. viride is capable of growing and sporulating with varied nutritional and environmental conditions, and, therefore, this strain of T. viride may be useful as a biocontrol agent under diverse physiological and environmental conditions.     

qPCR-based relative quantification of the brown algal endophyte <Emphasis Type="Italic">Laminarionema elsbetiae</Emphasis> in <Emphasis Type="Italic">Saccharina latissima</Emphasis>: variation and dynamics of host—endophyte interactions

Morphological changes—such as dark spots, twisted stipes and deformed blades—have been observed in wild and cultivated Saccharina latissima. The putative cause for the disease symptoms is the filamentous endophytic brown alga Laminarionema elsbetiae, which is known to invade stipes and fronds of its hosts. Little is known about this interaction and its occurrence in the field, although former studies indicated high endophyte prevalence in kelp populations. Previous epidemiological studies on kelp endophytes were mainly based on the examination of microscopic sections, followed by time-consuming isolation and cultivation steps in order to identify the endophyte and a reliable method to quantify endophyte infections was missing. As a novel approach, we established and validated a qPCR assay for relative quantification of the endophyte L. elsbetiae within its host S. latissima, which allows to examine both, the prevalence of endophytic algae and the severity of infections. The assay was shown to be highly specific and suitable to reliably detect small amounts of endophyte DNA in the host. Using this method, we detected very high endophyte prevalence in the investigated kelp populations, up to 100% in young S. latissima sporophytes in Brittany during spring. Furthermore, our results suggest that Saccharina sporophytes are infected early in their life and that seasonality and environmental factors have a significant impact on infection rates. In the future, this approach could also be applied to study other host-endophyte pairs using specific primers.     

Fingerprinting environmental conditions and related stress using stable isotopic composition of rice (Oryza sativa L.) grain organic matter

Sea level rise (SLR) is a primary factor responsible for inundation of low-lying coastal regions across the world, which in turn governs the agricultural productivity. In this study, rice (Oryza sativa L.) cultivated seasonally in the Kuttanad Wetland, a SLR prone region on the southwest coast of India, were analysed for oxygen, hydrogen and carbon isotopic ratios (δ¹⁸O, δ²H and δ¹³C) to distinguish the seasonal environmental conditions prevalent during rice cultivation. The region receives high rainfall during the wet season which promotes large supply of fresh water to the local water bodies via the rivers. In contrast, during the dry season reduced river discharge favours sea water incursion which adversely affects the rice cultivation. The water for rice cultivation is derived from regional water bodies that are characterised by seasonal salinity variation which co-varies with the δ¹⁸O and δ²H values. Rice cultivated during the wet and the dry season bears the isotopic imprints of this water. We explored the utility of a mechanistic model to quantify the contribution of two prominent factors, namely relative humidity and source water composition in governing the seasonal variation in oxygen isotopic composition of rice grain OM. δ¹³C values of rice grain OM were used to deduce the stress level by estimating the intrinsic water use efficiency (WUE_i) of the crop during the two seasons. 1.3 times higher WUE_i was exhibited by the same genotype during the dry season. The approach can be extended to other low lying coastal agro-ecosystems to infer the growth conditions of cultivated crops and can further be utilised for retrieving paleo-environmental information from well preserved archaeological plant remains.     

东海原甲藻与中肋骨条藻的种间竞争数值模拟

研究探讨了两个零维箱式模型在东海典型赤潮藻东海原甲藻和中肋骨条藻竞争与演替研究中的应用。模型在采用不同接种密度下的单种培养实验数据进行参数校正后,被用来模拟不同N/P条件下单种培养实验以及两藻种共培养竞争实验,并以实验数据对其结果进行了验证。模拟结果表明,在单种培养条件下,模型能够较好地重现两种藻在不同N/P环境中的生长及对营养盐的利用;共培养实验的模拟结果显示,在所有初始细胞密度比例条件下,中肋骨条藻的最终密度均会超过东海原甲藻,且PO4的消耗主要源于中肋骨条藻的利用,与实验结果一致,表明模型能够很好地体现两种藻的竞争结果及对营养盐的竞争关系;由于模型不足以模拟除营养盐竞争以外的藻间相互作用,模拟结果未体现东海原甲藻细胞数迅速衰减这一现象,有待进一步研究。     

Variation in growth,yield and protein concentration in <Emphasis Type="Italic">Saccharina latissima</Emphasis> (Laminariales,Phaeophyceae) cultivated with different wave and current exposures in the Faroe Islands

Ropes seeded directly with Saccharina latissima were deployed at different exposures (sheltered, current exposed and wave exposed) in a Faroese sound and characteristics of growth and quality of the biomass and surroundings were evaluated during the growth season from March to August 2015. Saccharina latissima individuals cultivated at the current exposed location were heavier compared to the individuals cultivated at the other locations; however, the total biomass yield was significantly lower at the current exposed location. The protein and nutritional value of the biomass varied with season but showed no correlation with exposure. The highest protein levels and EAA (essential amino acid) score were measured in the spring (April and May) samples. The amino acid composition was dominated by glutamate followed by aspartic acid; however, this was replaced by methionine in the July samples. Total Kjeldahl nitrogen was significantly higher in May and August compared to July, and the nitrate concentration in the biomass was significantly lower in May and August compared to July. Nitrate was most available in the seawater at the time of deployment (3rd of March) and decreased during spring and summer. Saccharina latissima was cultivated successfully at the sheltered, current exposed and wave exposed locations using a direct seeding method. However, our results indicate that the lower biomass yield at the current exposed cultivation location compared to the sheltered and wave exposed are due to the direct seeding method, and possible limitations using this method need further testing and optimization.     

Environmental Factors Affect Acidobacterial Communities below the Subgroup Level in Grassland and Forest Soils

In soil, Acidobacteria constitute on average 20% of all bacteria, are highly diverse, and are physiologically active in situ. However, their individual functions and interactions with higher taxa in soil are still unknown. Here, potential effects of land use, soil properties, plant diversity, and soil nanofauna on acidobacterial community composition were studied by cultivation-independent methods in grassland and forest soils from three different regions in Germany. The analysis of 16S rRNA gene clone libraries representing all studied soils revealed that grassland soils were dominated by subgroup Gp6 and forest soils by subgroup Gp1 Acidobacteria. The analysis of a large number of sites (n = 57) by 16S rRNA gene fingerprinting methods (terminal restriction fragment length polymorphism [T-RFLP] and denaturing gradient gel electrophoresis [DGGE]) showed that Acidobacteria diversities differed between grassland and forest soils but also among the three different regions. Edaphic properties, such as pH, organic carbon, total nitrogen, C/N ratio, phosphorus, nitrate, ammonium, soil moisture, soil temperature, and soil respiration, had an impact on community composition as assessed by fingerprinting. However, interrelations with environmental parameters among subgroup terminal restriction fragments (T-RFs) differed significantly, e.g., different Gp1 T-RFs correlated positively or negatively with nitrogen content. Novel significant correlations of Acidobacteria subpopulations (i.e., individual populations within subgroups) with soil nanofauna and vascular plant diversity were revealed only by analysis of clone sequences. Thus, for detecting novel interrelations of environmental parameters with Acidobacteria, individual populations within subgroups have to be considered.