Dugong habitat use in relation to seagrass nutrients,tides, and diel cycles

The dugong is the only herbivorous mammal that is strictly marine and a seagrass community specialist. The pasture available to the dugong varies with the tides because seagrass occurs in both intertidal and subtidal areas. We GPS-tracked seven dugongs within a 24 km², intensively used seagrass habitat in subtropical Australia in winter. We modeled resource selection within the habitat by comparing the dugongs’ use of space with the distribution of seagrass in an area defined using the combined space-use of the tracked animals. Selection by dugongs for seagrass quantity (biomass) and quality (nutrients) was analyzed within six time/tide combinations to examine the influences of tidal periodicity and the diel cycle on resource selection. Dugong habitat use was consistently centered over seagrass patches with high nitrogen concentrations, except during the day at low tides when the animals had fewer habitat choices and their space use was centered over high seagrass biomass. The association of dugongs with seagrass high in starch was positive during both day and night high tides when the animals could access the intertidal areas where seagrass biomass was generally low. Associations between dugongs and seagrass species were less definite, reflecting the potential for dugongs to exploit several species. Our model of dugong resource selection suggests that nitrogen is the primary limiting nutrient for dugong populations and also confirms the preference of dugongs for high-energy foods.     

Phytoremediation of Wastewater Containing Lead (Pb) in Pilot Reed Bed Using Scirpus Grossus

Phytoremediation is a technology to clean the environment from heavy metals contamination. The objectives of this study are to threat Pb contaminated wastewater by using phytoremediation technology and to determine if the plant can be mention as hyperaccumulator. Fifty plants of Scirpus grossus were grown in sand medium and 600 L spiked water in various Pb concentration (10, 30 and 50 mg/L) was exposed. The experiment was conducted with single exposure method, sampling time on day-1, day-14, day-28, day-42, day-70, and day-98. The analysis of Pb concentration in water, sand medium and inside the plant tissue was conducted by ICP-OES. Water samples were filtered and Pb concentration were directly analyzed, Pb in sand samples were extracted by EDTA method before analyzed, and Pb in plant tissues were extracted by wet digestion method and analyzed. The results showed that on day-28, Pb concentration in water decreased 100%, 99.9%, 99.7%, and the highest Pb uptake by plant were 1343, 4909, 3236 mg/kg for the treatment of 10, 30, and 50 mg/L respectively. The highest BC and TF were 485,261 on day-42 and 2.5295 on day-70 of treatment 30 mg/L, it can be mentioned that Scirpus grossus is a hyperaccumulator.     

Simultaneous production of propionic acid and vitamin B12 from corn stalk hydrolysates by Propionibacterium freudenreichii in an expanded bed adsorption bioreactor

Abstract

Vitamin B12 and propionic acid that were simultaneous produced by Propionibacterium freudenreichii are both favorable chemicals widely used in food preservatives, medicine, and nutrition. While the carbon source and propionic acid accumulation reflected fermentation efficiency. In this study, using corn stalk as a carbon source and fed-batch fermentation process in an expanded bed adsorption bioreactor was studied for efficient and economic biosynthesis of acid vitamin B12 and propionic. With liquid hot water pretreated corn stalk hydrolysates as carbon source, 28.65?mg L^?1 of vitamin B12 and 17.05?g L^?1 of propionic acid were attained at 168?h in batch fermentation. In order to optimize the fermentation outcomes, fed-batch fermentation was performed with hydrolyzed corn stalk in expanded bed adsorption bioreactor (EBAB), giving 47.6?mg L^?1 vitamin B12 and 91.4?g L^?1 of propionic acid at 258?h, which correspond to product yields of 0.37?mg g^?1 and 0.75?g g^?1, respectively. The present study provided a promising strategy for economically sustainable production of vitamin B12 and propionic acid by P. freudenreichii fermentation using biomass cornstalk as carbon source and expanded bed adsorption bioreactor.     

Paracoccus denitrificans SD1 mediated augmentation with indigenous mixed cultures for enhanced removal of N,N-dimethylformamide from industrial effluents

Bioaugmentation is an effective treatment method to reduce recalcitrant pollutants from polluted sites. Dimethylformamide (DMF) is a very common toxic organic solvent among the effluents of textile and pharma industries. DMF was degraded by pre-adapted Paracoccus denitrificans SD1 with indigenous mixed cultures in both bioaugmentation and non-bioaugmentation conditions. In free cell condition, augmentation was not much significant due to competition among the bacterial cells and direct exposure of cells to toxic level of DMF. To enhance the degradation of DMF, cells were entrapped in PVA–alginate matrix individually and collectively for bioaugmentation experiments. Bioaugmentation is successful when immobilized P. denitrificans SD1 is introduced higher inoculum volume with indigenous cultures in continuous packed bed reactor system. This treatment has succeeded in removing 91.3% of 3% (v/v) DMF from the industrial effluent. This investigation advocates that bioaugmentation enhances the DMF removal efficiency by about 20% when compared to individual degradation by P. denitrificans SD1.     

Stream bed substrate composition adjacent to different riparian land-uses in Iowa, USA

Extensive land-use changes in Iowa have increased erosional processes and the amount of fines deposited on stream beds. Large amounts of fines cover the other bed substrate that are essential habitat for invertebrates and fish. In Iowa and other agricultural Midwestern states, riparian conservation land-uses are being established to minimize sediment inputs to streams. This study compared stream bed substrate composition in reaches adjacent to: riparian forest buffers, grass filters, row-cropped fields, pastures with cattle fenced out of the stream and continuous, rotational and intensively grazed rotational pastures, in three regions of Iowa. The objective was to examine the impacts of the adjacent riparian land-uses on stream bed substrate composition. The percentages of fines in this study ranged from: 36 to 63% in the central region; 10 to 31% in the northeast region; and 22 to 85% in the southeast region. The high percentage of fines in most stream bed reaches indicates high embeddedness. The high embeddedness resulted in the few significant differences in substrate percentages among riparian land-uses. Decades of agricultural land-uses have heavily impacted stream beds and only significant reductions in surface and bank erosion at the watershed scale can begin to reverse this trend. There were indications that riparian forest buffers and to a lesser degree, pastures with cattle fenced out of the stream, could decrease fines resulting in a more diverse substrate composition. Overall, more targeted approaches for the establishment of conservation land-uses in combination with other restoration practices (e.g. in-stream enhancements) are required to successfully decrease fines on stream beds.     

New processes and actual trends in biotechnology

Abstract: A survey of immobilization techniques with special emphasis on alginate entrapment and micro hollow spheres is presented. The advantages and disadvantages of immobilization are discussed. Industrial applications of immobilization are demonstrated, especially biosensors and production of acrylamide. The fundamentals of bioprocesses with reduced water content and application as well as process examples are presented.     

Sunspots drive seagrasses

Seagrasses are underwater flowering plants that form an important marine habitat worldwide. They respond to watershed and climate influences and are considered a good indicator of environmental health. Investigations into seagrass photosynthesis, response to high irradiance and UV light are providing new insights into controls on plant production. We show that the size and density of the intertidal seagrass directly relates to sunspot activity. The influence of sunspot activity has been largely overlooked in plants and never examined in seagrasses. The correlation between seagrass canopy height and the number of sunspots was highly significant, with height decreasing steadily as sunspots increase and recover only after a substantial decline in sunspot activity. The density of seagrass shoots correlated positively with sunspots until, at high sunspot numbers (>110 per month), plant density dropped and then rebounded. High sunspot activity inhibits the production and alters the meadow structure of tropical intertidal seagrass habitats.     

Structural complexity facilitates accumulation and retention of fragments of the invasive alga, Caulerpa taxifolia

Free-drifting fragments represent an abundant potential source of recruits to the invasive alga, Caulerpa taxifolia. Here we examine how this fragment pool interacts with real and artificial habitat structure in estuarine environments. Specifically, we tested two hypotheses; (i) the fragment pool was unrelated to the structural complexity of Caulerpa beds and, (ii) fragment accumulation and retention was unrelated to canopy height of seagrass meadows. We examined fragment accumulation and retention using artificial seagrass units (ASUs) mimicking seagrasses with long (20 cm) leaves (Posidonia/Zostera) and short (5 cm) leaves (Halophila spp.). Both hypotheses were rejected. Fragment biomass was a positive function of the blade height and cover of Caulerpa taxifolia. ASUs with structure had greater fragment accumulation than controls, but we did not detect differences between ASUs of different canopy heights. However, fragment accumulation within ASUs was strongly affected by site, with the site experiencing the strongest tidal flows accumulating the most fragments. Structurally complex ASUs also retained more fragments relative to the bare control, but the degree of complexity did not affect retention and we could not distinguish between ASUs of different canopy height and the procedural control (metal frame lacking ‘leaves’). Overall, we conclude that the entanglement of C. taxifolia fragments is facilitated by structurally complex habitat and likely contributes to the successful establishment of this invader.