Suspended Bags Research Articles

Bivalve aquaculture and eelgrass: A global meta-analysis

The marine, intertidal zone is the optimal environment for eelgrass (Zostera spp.) and bivalve aquaculture. Eelgrass is a valuable and protected nearshore habitat. It is important to understand how bivalve aquaculture interacts with eelgrass to support the sustainable development of this globally expanding industry. This study provides a comprehensive understanding of the positive and negative effects of bivalve aquaculture on eelgrass by conducting the first quantitative, global meta-analysis of aquaculture-eelgrass studies. A literature review resulted in 125 studies that met established criteria for inclusion in this analysis. The meta-analysis determined: (1) how eelgrass responds to on-bottom and off-bottom bivalve aquaculture, (2) how these responses vary between regions and specific grow-out methods, and (3) the resilience of eelgrass after harvesting disturbances. On-bottom culture (laying directly on the sediment potentially including predator exclusion devices) corresponded to significant increases in eelgrass growth and reproduction, and a decrease in density and biomass. Off-bottom culture (e.g., longline and suspended bag) resulted in significant decreases in eelgrass density, percent cover, and reproduction. Results support a space-competition hypothesis for on-bottom culture and provide limited support for light limitation in off-bottom culture, although other mechanisms of interaction are potentially occurring as well. A US west coast case study revealed regional differences in eelgrass responses, including a more negative trend in eelgrass density from off-bottom culture, and a neutral effect on reproduction from on-bottom culture (relative to neutral and positive trend, respectively, in the average of all other studies). Eelgrass densities recovered after all harvest methods, however mechanical harvest methods created greater initial impact and longer recovery times than manual harvest methods. The time-period over which observations were reported was an important variable that was not included in the analysis but could influence these results. These analyses suggest the response of eelgrass to bivalve aquaculture varies depending on eelgrass characteristics, grow-out approaches, and harvesting methods, with potential regionally specific relationships. Questions remain, regarding how this dynamic relationship between eelgrass and aquaculture habitat relates to ecological functions and services in the nearshore environment.

Removal of phosphorus using suspended reactive filters (SRFs) - efficiency and potential applications.

The removal of phosphorus (P) from agricultural runoff is essential to reduce the threat of eutrophication in bodies of water. In this study, an alternative method of applying P reactive materials (RMs) in the form of suspended reactive filters (SRFs) is presented. The SRF method enables P which has already entered a body of water to be caught. In this study, an autoclaved aerated concrete (AAC) was used as the SRFs. The experiment was carried out in a laboratory in a hydraulic block of 1 m in width and 2 m in length. Three curtains, consisting of eight suspended bags filled with the AAC, were used. The ratio of RM mass to water volume in the hydraulic block was 3:1 (g:dm3). The initial concentration of P amounted to 1.335 mg P-PO4·dm-3. The results demonstrated the successive reduction of P in the water over the experiment duration and the number of cycles in which water passed through the system of curtains. SRFs filled with AAC decreased the level of P-PO4 in the solution to 0.190 mg·dm-3. The highest removal efficiency (50% overall P reduction) was observed at the beginning of experiment, when the average unit sorption amounted to 0.192 mgP-PO4·g-1.

Filtration curtains for phosphorus harvesting from small water bodies

The reactive material (RM) Polonite® in the form of suspended filter (Suspended Reactive Filter, SRF) was used in the study. The experiment was carried in laboratory in hydraulic block of 1m width and 2m length. Three curtains consisted of eight suspended bags filled with the reactive material were used. The total mass of the reactive material was 1200g per experiment. The ratio of the mass of the reactive material to the water volume in hydraulic block was 3:1 (g:dm3). The initial phosphorus concentrations were 1.439; 1.852; 2.384 and 3.012mgP–PO4dm−3 in different tests, corresponding to the polluted surface water in Poland. The results showed successive reduction of phosphorus from water in the time of experiment and number of cycles when water passed through the system of curtains of SRF. Regardless of the initial concentration, SRF decreased level of P–PO4 in solution of 0.517±0.018mgdm−3 at average. Base on the results, the nomogram supporting practical implementation of the RM Polonite® has been created for the estimation of the mass of the RM depending on the initial and desired final concentration of phosphorus in water.

Experimental determination of the effects of light limitation from suspended bag oyster (Crassostrea virginica) aquaculture on the structure and photosynthesis of eelgrass (Zostera marina)

Recent studies have hypothesized reduced eelgrass distribution in areas exposed to suspended bag oyster aquaculture of Crassostrea virginica in Eastern Canada is related to shading from aquaculture stock and equipment. The results of a 359-day manipulative field experiment support this hypothesis. Reductions in underwater light, at levels comparable to those found at suspended oyster operations, caused reduced eelgrass structure, morphometrics, and photosynthesis. Increased organic matter deposition under suspended bags neither led to biologically relevant declines in eelgrass metrics, nor mitigated the effects of light limitation. Shoot density, above-ground biomass, below-ground biomass, canopy height, leaf area index, leaf width, and photosynthetic capacity were all significantly reduced. These variables declined along a gradient of increased shading, with significant responses detected in as few as 67days after exposure to 26% subsurface irradiance. Subsequent sampling 253days after the removal of experimental treatments documented the potential for recovery in the form of seedling recruitment to the plots of heaviest impact. However, eelgrass response variables remained significantly reduced relative to controls, indicating previous assumptions of a rapid recovery potential for eelgrass exposed to suspended bag oyster aquaculture were incorrect.

Inaccuracy of fluid container volume markings

During an emergency neurosurgical procedure, a patient was given 250 ml mannitol 20%. The volume was estimated visually according to the gradations marked on either side of the 500-ml fluid bag, but there was a suspicion that these did not correlate closely with the volume infused. Postoperatively, the residual volume of mannitol was drawn off using a 50-ml syringe, and found to measure 270 ml. On withdrawing 100-ml aliquots from suspended bags of mannitol 20% and saline 0.9% (both Baxter, Thetford, UK) using a 50-ml syringe (BD Plastipak, BD, Oxford, UK), sequential meniscus levels were found to differ considerably from their isovolumetric bag markings (Figs 7a and 7b). It is clear that the fluid bag gradations do not represent the remaining volume. As mis-information is less desirable than no information, I suggest these markings are removed. An alternative would of course be accurate placement of the same.

Small-fast growers of Mytilus galloprovincialis do not catch up: an experimental test with size-graded mussels cultured in longline suspended bags

This study addresses the growth dynamics of three size groups of juveniles graded from the same wild cohort of the Mediterranean blue mussel Mytilus galloprovincialis. Each size group was replicated and cultured independently from the others in culture bags suspended from a specific longline system devised for this task. The small size group of mussels showed an unexpected higher growth rate SGR (0.95 ± 0.07) than the intermediate size group (0.41 ± 0.08) or the large size group (0.32 ± 0.10) from the beginning of the experiment. Nevertheless, all three size groups grew more slowly with time and the initially large size group was conspicuously and significantly larger than the rest of size groups at the end of the experiment. Early selection of fast growers by grading on shell length is a straightforward approach to accelerate the fattening period. Speeding up harvest can be a natural tool to skip upwelling episodic blooms of toxic microalgae or to improve the final stock performance of cultured blue mussels.

Meiofaunal recruitment to mimic pneumatophores in a cool-temperate mangrove forest: spatial context and biofilm effects

A field experiment was devised to test whether meiofauna that colonised mimic pneumatophores (artificial substrates) resembled the assemblage on adjacent live pneumatophores in three randomly chosen intertidal, estuarine sites. The experiment showed that the close proximity of particular biota on living pneumatophores did not reliably influence subsequent development of assemblages upon mimic pneumatophores within a scale of 10 m during a colonisation period of less than 20 weeks. There was some convergence of the composition of the colonising assemblage of meiofauna on mimic pneumatophores with the local assemblages in sites dominated by barnacles, or where the natural pneumatophores were free from macroscopic epibionts. However, tychopelagic meiofauna from algal epiphytes did not significantly colonise mimic pneumatophores during the 20-week trial, probably due a lack of growing algae. During the conditioning phase suspended in water at a marine site 20 km from the mangroves, mimic pneumatophores acquired an assemblage of meiofauna different from the estuarine assemblage that colonised mimics following implantation in the estuarine mudflat. Enhanced colonisation rates of mimics in suspended bags at the conditioning site may be explained by the absence of benthic macroinvertebrates, and the lack of intertidal exposure. Biofilms aged 2, 7, and 11 weeks had no consistent, different effect on the subsequent colonisation of meiofauna. We conclude that divergence of phytal-based assemblages of meiofauna depends upon the amount of coverage, as well as the type, of fouling macro-epibionts on the pneumatophores. Meiofaunal assemblages on artificial substrates after 20 weeks colonisation displayed less intrinsic patchiness than mature phytal assemblages on natural pneumatophores, and so present a potentially useful way of improving the power of biomonitoring applications using meiofauna.

Buffy coat platelets stored in apyrase, aprotinin, and ascorbic acid in a suspended bag: combined strategies for reducing platelet activation during storage

Platelet activation is an important factor impeding the clinical effectiveness of platelet transfusions. In this study, platelet concentrates (PCs) were prepared by a novel suspended-bag buffy coat technique that was followed by the addition of a mixture of platelet activation inhibitors to the storage bag. In vitro platelet function was evaluated in PCs prepared by the suspended-bag buffy coat technique and stored at 22 degrees C for 5 days in the presence of (n = 12) or absence (n = 12) of apyrase, ascorbic acid, and aprotinin (AAA). Platelets from AAA-incubated PCs demonstrated mean ATP levels 17 percent (p < 0.004), 13 percent (p < 0.02), and 22 percent (p < 0.003) higher than those measured in parallel control PCs on Days 1, 3, and 5, respectively. Similarly, on Days 3 and 5 of storage, respectively, 45-percent (p < 0.001) and 50-percent (p < 0.001) greater ADP-induced maximum aggregation was observed in AAA-incubated PCs than was seen in control preparations. AAA-incubated PCs demonstrated alpha-granule membrane protein-140 expression 92 percent (p < 0.01), 133 percent (p < 0.003), and 104 percent (p < 0.001) below that in control PCs on Days 1, 3, and 5, respectively. At similar intervals, a significant increase in recovery from hypotonic shock also was observed in AAA-incubated PCs. Further, Day 5 AAA-PCs demonstrated significantly higher morphology scores and O2 consumption than did control preparations. Buffy coat platelets prepared in suspended bags and stored in the presence of AAA demonstrate significantly reduced activation and enhanced functional and metabolic activity.

A Novel Technique for Preparing Improved Buffy Coat Platelet Concentrates

ABSTRACT We evaluated in vitro platelet function of platelet concentrates stored at 22 C for 5 days prepared either by the conventional pelleting procedure or platelet concentrates prepared from buffy coats by utilizing a novel bucket designed to support a suspended bag. For platelet concentrates from buffy coat, whole blood was centrifuged at 3,000 x g for 13 min, with all but 30cc of the cell poor plasma transferred to a satellite bag, followed by a second centrifugation at 170 x g for 5 min utilizing our novel centrifugation device. For pelleted platelets, whole blood was centrifuged at 2,000 x g for 3 min, platelet rich plasma removed, centrifuged, and the pellet resuspended in plasma. Leukocyte contamination in buffy coat platelet concentrates was reduced by 95% (p<0.001) in comparison to pelleted platelets. Further, platelets from buffy coat platelet concentrates demonstrated significantly enhanced ADP-induced aggregation, increased recovery from hypotonic shock, higher morphology scores, and reduced GMP-140 expression in comparison to pelleted preparations. No differences in O 2 consumption, CO 2 production, pH and total ATP were observed between the two types of preparations at day 5 of storage. Our results indicate that platelet concentrates from buffy coat, prepared by a suspended storage bag centrifugation technique, are superior with respect to in vitro platelet function when compared to pelleted platelets.

Influence of microarthropod abundance and climatic factors on weight loss and mineral nutrient contents of Eucalyptus leaf litter during decomposition

Densities of the different taxa of microarthropods per gram of litter in litter bags varied widely from the rainy to the dry season. Collembola and Acarina constituted more than 86% of the total microarthropods, and occurred in significantly greater numbers in the coarse-mesh bags than the fine-mesh bags. There were no fauna in the litter of suspended bags. The average weight loss was greater in the coarse-mesh bags (50.4%) than in the fine-mesh bags (44.5%), and the suspended bags (7.4%). Similarly, the concentrations of N and Ca were greater in the litter of coarse-mesh bags compared to that of the fine-mesh bags. In contrast, the concentrations of P and K were comparatively lower in coarse-mesh bags. The mass loss of litter showed a negative linear correlation with the total Collembola and with litter temperature. The N concentrations in the litter in both the mesh bags showed negative correlations with the abundance of total Collembola, and with that of Lepidocyrtus sp. and Sminthuridae, and rainfall. The N concentration in the litter in the coarse-mesh bags was positively correlated with the total number of arthropods but, surprisingly, was negatively correlated with the total number of Acarina. The concentration of Ca showed negative correlations with rainfall and litter moisture only. The P concentration showed positive correlations with total Collembola, with Lepidocyrtus sp. and Sminthuridae in both the mesh bags, with rainfall in the fine-mesh bags, and with total microarthropods in the coarse-mesh bags.

Some factors affecting the infestation of wheat and maize by Sitophilus oryzae (L.) and Sitophilus zeamais Mots. (Coleoptera: Curculionidae)

Cultures of various stocks of S. oryzae (L.) and S. zeamais Mots. were maintained for several generations at 25°C and 70% r.h. on both wheat and maize, on only one of these foods, or on rice. In every generation a subsample of adults was placed in a mixture of wheat and maize (equal weights of each) for 5 days, after which the two cereals were separated and incubated and the number of progeny counted. A substantial majority of S. oryzae and much less substantial majority of S. zeamais emerged from wheat. In both species the majority was a little less when the laying adults had passed their developmental stages upon maize or rice. In alternate generations the foods were presented to another subsample in separate piles 40 cm apart. The progeny distribution was very similar to that found with intermingled foods. In intervening generations the foods were presented to S. zeamais in suspended bags which could only be reached by flight. When this occurred, more emergences, in many cases over 90%, were found from maize than wheat. When the adults associated with the suspended bags were counted at the end of the 4-day experiment the numbers were as one would expect from the emergences. When similar counts were made daily, however, approximately equal numbers were found associated with each food and observations suggested that directional flight by females did not take place.

Experiments on the diffusibility of alkaloids through rubber.

Rosenbloom and Gies have found that various ether-soluble substances, when dissolved in ether and placed in rubber bags immersed in ether, readily pass through the rubber membranes thus imposed. We have found that various alkaloids and some related substances readily diffuse through rubber under such conditions. Our experiments were conducted as follows: A moderate quantity of the pure ether-soluble substance was mixed with 15–25 c.c. of ether. This mixture was poured through a funnel into a new air-tight rubber condom in such a way as to preclude the possibility of overflow upon the external surface. The bag was then immersed in about 50 c.c. of ether in a narrow salt-mouth bottle 7 inches high. With the bag suspended at full extension in this position, its mouth was about an inch above the opening in the bottle. The protruding condom was supported in the neck of the bottle by a tightly fitting cork stopper, which also served to keep the bag closed. After a diffusion period of convenient length (sometimes 2 to 5 days), the condom was removed from the bottle, the ether diffusate was poured into a porcelain dish, and the ether completely removed by evaporation on a steam bath. At least one appropriate test was then applied to the residue. Meanwhile, the ether solution in the condom was removed. A large volume of water was then poured into the suspended bag, which, during its distention by the water, was carefully examined for signs of leakage. In a few instances defective membranes temporarily rendered the outcome doubtful. All results with such bags were ignored, of course. Each of the tests, even after reliable positive responses, was repeated at least once with a new rubber bag.