Sedimentary Nitrogen Uptake & Assimilation in the Temperate Zooxanthellate Anemone Anthopleura aureoradiata

<p>This study investigated the potential for, and efficiency of, particulate nitrogen uptake from the sediment and subsequent consequences of this on the nutrient status of endosymbiotic dinoflagellates (zooxanthellae) in the temperate zooxanthellate anemone Anthopleura aureoradiata. Sediment was collected from a mudflat and labelled with (15NH4)2SO4 before being provided to A. aureoradiata at low (5 g dry weight) and high sediment (20 g dry weight) loads for 6 hours. While no discernible change in the isotopic content of the sediment could be detected, analysis of the host and algal symbionts revealed that 15N had been taken up. Uptake by the host was similar at both high and low sediment loads, but the algal symbionts acquired more nitrogen at the lower load (1.13 versus 0.93 atom % 15N in the low and high loads, respectively). Evaluation of this particulate nitrogen uptake from the sediment was further examined by measuring the nitrogen status of the zooxanthellae. This was determined by measuring the extent to which ammonium (40 muM NH+4) enhanced the rate of zooxanthellar dark carbon fixation above that seen in filtered seawater (FSW) alone; the enhancement ratio was expressed as [dark NH+4 rate/dark FSW rate]. VD'/VL, a further index of nitrogen status, was also calculated where VD' = [dark NH+4 rate - dark FSW rate] and VL = rate of carbon fixation in the light. When anemones were starved for 2-8 weeks, zooxanthellar nitrogen deficiency became apparent at greater than or equal to 4 weeks, with NH+4/FSW and VD'/VL averaging up to 2.90 and 0.11, respectively. In comparison, when anemones were fed 5 times per week for 8 weeks the addition of ammonium had little effect, indicating nitrogen sufficiency; NH+4/FSW and VD'/VL values were 1.03 and -1.0 x 10-3, respectively. The nitrogen status of zooxanthellae from anemones starved and incubated with and without sediment was examined with no apparent difference between sediment and no sediment treatments; zooxanthellar nitrogen deficiency became apparent at greater than or equal to 4 weeks in both treatments, with NH+4/FSW and VD'/VL averaging up to 3.73 and 0.17 for the sediment treatment and 2.74 and 0.15 for the no sediment treatment, respectively. The nitrogen status of zooxanthellae from anemones found on a mudflat (Pauatahanui Inlet) and a rocky intertidal site (Kau Bay) was different. Zooxanthellae from mudflat anemones were nitrogen sufficient with NH+4/FSW and VD'/VL values averaging up to 1.26 and -6.0 x 10-3, respectively. Nitrogen deficient zooxanthellae were present in anemones from the rocky intertidal. Anemones from tide pools in the upper littoral zone had NH+4/FSW and VD'/VL values of 2.99 and 0.11, respectively, while anemones from the mid littoral zone had NH+4/FSW and VD'/VL of 2.90 and 0.13, respectively; there was no significant difference in nitrogen status between zooxanthellae from high shore tide pool anemones and aerially exposed mid-littoral anemones. These results suggest that while particulate nitrogen can be taken up from the sediment by this species, dissolved inorganic nitrogen such as ammonium in the seawater, and especially the interstitial water surrounding infaunal anemones on mudflats, may be a more important source of nitrogen in the field.</p>

Sedimentary Nitrogen Uptake & Assimilation in the Temperate Zooxanthellate Anemone Anthopleura aureoradiata

<p>This study investigated the potential for, and efficiency of, particulate nitrogen uptake from the sediment and subsequent consequences of this on the nutrient status of endosymbiotic dinoflagellates (zooxanthellae) in the temperate zooxanthellate anemone Anthopleura aureoradiata. Sediment was collected from a mudflat and labelled with (15NH4)2SO4 before being provided to A. aureoradiata at low (5 g dry weight) and high sediment (20 g dry weight) loads for 6 hours. While no discernible change in the isotopic content of the sediment could be detected, analysis of the host and algal symbionts revealed that 15N had been taken up. Uptake by the host was similar at both high and low sediment loads, but the algal symbionts acquired more nitrogen at the lower load (1.13 versus 0.93 atom % 15N in the low and high loads, respectively). Evaluation of this particulate nitrogen uptake from the sediment was further examined by measuring the nitrogen status of the zooxanthellae. This was determined by measuring the extent to which ammonium (40 muM NH+4) enhanced the rate of zooxanthellar dark carbon fixation above that seen in filtered seawater (FSW) alone; the enhancement ratio was expressed as [dark NH+4 rate/dark FSW rate]. VD'/VL, a further index of nitrogen status, was also calculated where VD' = [dark NH+4 rate - dark FSW rate] and VL = rate of carbon fixation in the light. When anemones were starved for 2-8 weeks, zooxanthellar nitrogen deficiency became apparent at greater than or equal to 4 weeks, with NH+4/FSW and VD'/VL averaging up to 2.90 and 0.11, respectively. In comparison, when anemones were fed 5 times per week for 8 weeks the addition of ammonium had little effect, indicating nitrogen sufficiency; NH+4/FSW and VD'/VL values were 1.03 and -1.0 x 10-3, respectively. The nitrogen status of zooxanthellae from anemones starved and incubated with and without sediment was examined with no apparent difference between sediment and no sediment treatments; zooxanthellar nitrogen deficiency became apparent at greater than or equal to 4 weeks in both treatments, with NH+4/FSW and VD'/VL averaging up to 3.73 and 0.17 for the sediment treatment and 2.74 and 0.15 for the no sediment treatment, respectively. The nitrogen status of zooxanthellae from anemones found on a mudflat (Pauatahanui Inlet) and a rocky intertidal site (Kau Bay) was different. Zooxanthellae from mudflat anemones were nitrogen sufficient with NH+4/FSW and VD'/VL values averaging up to 1.26 and -6.0 x 10-3, respectively. Nitrogen deficient zooxanthellae were present in anemones from the rocky intertidal. Anemones from tide pools in the upper littoral zone had NH+4/FSW and VD'/VL values of 2.99 and 0.11, respectively, while anemones from the mid littoral zone had NH+4/FSW and VD'/VL of 2.90 and 0.13, respectively; there was no significant difference in nitrogen status between zooxanthellae from high shore tide pool anemones and aerially exposed mid-littoral anemones. These results suggest that while particulate nitrogen can be taken up from the sediment by this species, dissolved inorganic nitrogen such as ammonium in the seawater, and especially the interstitial water surrounding infaunal anemones on mudflats, may be a more important source of nitrogen in the field.</p>

Operation intensification methods of aggressive industrial sewage neutralization facilities

To neutralize the waste pickling solutions and rinsing water, resulting from cleaning metal products s surface of rust by acids solutions, lime is used. Being cheap, this method of sewage neutralization has considerable drawbacks. Forming in the technological pipes strong gypsum depositions and low specific productivity of the equipment for sediment dewatering are most significant of them. Characteristic of aggressive industrial sewage, formed at pickling of ferrous metals presented. Methods of elimination of drawbacks of industrial sewage neutralization by lime considered, including stabilization of neutralized industrial sewage and control of properties of the sediment formed. It was noted, that stability of the circulating water can be provided by accelerating of crystallization of the forming gypsum sediments by introducing in it fine priming powder and heating the neutralized water up to 65-70 °С followed by thermal softening of a part of circulating water, removed out of the circulating system. It was shown, that the heating of the water and the ongoing changes of the composition and properties of the sediment result in decrease of filtration resistance 2-3 folds, increase of deposition speed 3-4 folds and decrease the sediment volume 1.5-2 folds comparing with lime neutralization in cold water. Calculated dozes of lime at the heating were taken the same as at the regular lime neutralization. Elimination of the circulating water oversaturation by bi-water gypsum can be reached also by addition into the water of powder-like gypsum pulp - priming powder for microcrystals of the gypsum, followed by aeration during 30-40 min. This method was tested under industrial conditions. Technological properties of the forming sediment can be improved by sediment treatment by flocculants and preliminary heating of the neutralized water up to 65-70 °С. Control of technological properties of the sediment is done by addition of flocculants and heating of the neutralized water. Recommendations for improving operation of the neutralization facilities presented with indicating particular technological parameters of the equipment operation for sewage and sediment treatment.

Survival durations and behavioural adjustments of two freshwater bivalves (Unio terminalis, Unionida and Corbicula fluminea, Venerida) under two emersion conditions

Freshwater bivalves in shallow waters are often exposed to extended periods of drought and are highly affected due to their limited mobility. Their adaptation to emersion is a key factor for survival, particularly during human-made unnatural water regime fluctuations or short-term droughts. In the current study, survival durations of two freshwater bivalve species (Unio terminalis, Unionidae and Corbicula fluminea, Cyrenidae) were tested under two experimental emersion conditions (presence of water-saturated sediment and without sediment). U. terminalis' mean survival duration more than doubled in the water-saturated sediment treatment (992 h) compared to treatment without sediment (448 h). For C. fluminea, the mean survival duration in the water-saturated sediment treatment (278 h) was over 50% longer than that recorded in the treatment without sediment (174 h). Both species probably made behavioral adjustments according to the environmental conditions to respond to the presence of the water-saturated sediment and maximized their survival chances. In general, U. terminalis survived significantly longer than C. fluminea in both treatments. No effects of size on survival were observed for either species.