Marine Suspension Research Articles

Nauti-Craft Marine Suspension System - Suspension System to Reduce Vesselʼs Vibration and Improve Its Deck Attitude

Nauti-Craft Marine Suspension System - Suspension System to Reduce Vesselʼs Vibration and Improve Its Deck Attitude

Seasonal and interannual variability of feeding in Antarctic benthos

AbstractThe seasonal and interannual variability of feeding in 15 species of benthic marine suspension feeder was studied over 8 yr at Ryder Bay, Antarctica. Feeding was strongly seasonal in bryozoans, gorgonians, polychaetes, and dendrochirote holothurians. The winter non‐feeding period was longest in the holothurians and shortest in bryozoans. Bryozoans started feeding in late winter at very low chlorophyll concentrations, often when surface fast‐ice was still present. In hydroids and actinians, feeding tentacles were deployed continuously throughout the year, though hydroid feeding intensity declined slightly in late winter. Water column phytoplankton biomass was strongly seasonal with marked interannual variability in the timing and intensity of the bloom, driven principally by ice dynamics. Correlation across years between the start of feeding and the development of the bloom was poor, and in seasons when a dense spring bloom of benthic filamentous microalgae developed, the start of feeding in many benthic species was delayed. This study indicates that feeding in benthic marine suspension feeders in Antarctica is influenced by factors additional to the seasonal availability of food in the water column.

Model-assisted measurements of suspension-feeding flow velocities.

Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis, measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers (Re). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re, pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8 to 520, and exhalant Re ranged from 15 to 1073. Volumetric pumping rates ranged from 1.7 to 7.4 l h-1 for M. arenaria, 0.3 to 3.6 l h-1 for M. mercenaria and 0.07 to 0.97 l h-1 for C. intestinalis We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies.

INFLUENCE OF WIND INTENSITY AND DIRECTION ON CHARACTERISTICS OF AEOLIAN FLOWS IN THE COASTAL ZONE

One of the main tasks of the Project «Creation of monitoring system of natural conditions state and variability in the «land and sea» interaction zone» is determination of influence of hydrometeorological conditions within research area (coastal zone of the Black Sea) on qualitative and quantitative content of substance of sediment flows in atmospheric and marine environments. This project is carrying out by researchers from Institute of Geological Sciences, NAS of Ukraine, on the bases of Experimental Branch of Marine Hydrophysical Institute NAS of Ukraine (Kacively village). The data base of wind speed and directions, intensity of wave processes, amount of precipitations, data of monthly sampling of Aeolian material of atmospheric flows of different direction, data of monthly sampling of marine suspension from different depths was created. Analytical investigations and natural material proceeding allowed identifying dependencies. Our investigations showed that research of mechanisms of sedimentation material inflow from the coastal zone to the sea expedient not only for knowledge of metabolic processes in «land and sea» interaction zone but also determine regularities of contaminants transfer within this zone.

Trematode infections reduce clearance rates and condition in blue mussels Mytilus edulis

Suspension feeders are important players in coastal food webs: by filtering particles suspended in the water column and depositing faeces and pseudofaeces in sediments, they mediate the coupling of pelagic primary and benthic secondary production. However, the potential interference of parasite infections on suspension feeding is not well investigated. We experimentally determined the effect of infections with metacercariae of the common trematode Renicola roscovita on clearance rates and condition of blue mussels Mytilus edulis. We also investigated whether there were differences in the effects of infections between different size classes of mussels. Using controlled infections under lab conditions, our experiment showed that infections significantly reduced the clearance rates of mussels. This effect was less pronounced in small (42% reduction) than in large mussels (71%). In addition, infections significantly reduced mussel body mass index in large (23% reduction) and small (17%) mussels compared to uninfected mussels. These reductions most likely resulted from a combined effect of an interference of the parasites with the mussel’s feeding apparatus (with the palps being the preferred infection site of the parasite) and of the energetic demands of the parasites (with metacercariae growing in size after initial infection). These negative effects on mussel filter feeding capacity indicate that parasites can alter a crucially important functional trait of marine suspension feeders.

Deposition of carbon nanotubes by a marine suspension feeder revealed by chemical and isotopic tracers

Carbon nanotubes (CNTs) are one of the few truly novel nanomaterials and are being incorporated into a wide range of products, which will lead to environmental release and potential ecological impacts. We examined the toxicity of CNTs to marine mussels and the effect of mussels on CNT fate and transport by exposing mussels to 1, 2, or 3mg CNTsl−1 for four weeks and measuring mussel clearance rate, shell growth, and CNT accumulation in tissues and deposition in biodeposits. We used metal impurities and carbon stable isotope ratios of the CNTs as tracers of CNT accumulation. Mussels decreased clearance rate of phytoplankton by 24% compared with control animals when exposed to CNTs. However, mussel growth rate was unaffected by CNT concentrations up to 3mgl−1. Based on metal concentrations and carbon stable isotope values, mussels deposited most CNTs in biodeposits, which contained >110mg CNTsg−1 dry weight, and accumulated about 1mg CNTsg−1 dry weight of tissue. We conclude that extremely high concentrations of CNTs are needed to illicit a toxic response in mussels but the ability of mussels to concentrate and deposit CNTs in feces and pseudofeces may impact infaunal organisms living in and around mussel beds.

Active Vibration Control for Marine Platform Flatness Using Sliding Mode Scheme

Various industries adopt different techniques for isolating or reducing vibration. This paper investigates flatness control for fitted equipment on marine vessels which are subject to random sea wave. These disturbances significantly affect the operational quality and durability of marine systems, thereby decreasing overall safety. In hostile environments where safety considerations are important, vibration isolators are often used to suppress the effects of vibrations. The system described here is based on a four degree-of-freedom active marine suspension model, which allows for effective disturbance rejection. Sliding Mode Control (SMC) is then used to reduce the disturbance simulated as random sea waves. It has been shown that this method offers the advantages of easy implementation, reduced maintenance requirements, increased system efficiency and reduced vibration.

Size Selectivity in Artificial Cilia–Particle Interactions: Mimicking the Behavior of Suspension Feeders

Inspired by the ability of marine suspension feeders to selectively capture small particles by their hairlike cilia, we simulate the interaction between artificial cilia and microscopic particles of different sizes to determine if a purely synthetic system can display analogous size-selective behavior. Our computational approach specifically models the capture of particles suspended in the surrounding fluid by adhesive filaments, which are anchored by one end to a surface. Via this model, we show that this size selectivity can arise as a result of adhesive and hydrodynamic interactions in the system. The substantial reduction in the mobility of the large particles near surfaces leads to a failure in capturing large particles. Using a simple analytical model, we show that the balance of hydrodynamic and adhesive forces favors capture of particles below a critical size for a given cilia-particle interaction. Our findings provide guidelines for designing artificial cilia that can be used for sorting and transporting particles within microfluidic devices.

Identifying trophic variation in a marine suspension feeder: DNA- and stable isotope-based dietary analysis in Mytilus spp.

Accurate field data on trophic interactions for suspension feeders are lacking, and new approaches to dietary analysis are necessary. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was integrated with stable isotope analysis to examine dietary patterns in suspension-feeding Mytilus spp. from seven spatially discrete locations within a semi-enclosed marine bay (Strangford Lough, Northern Ireland) during June 2009. Results of the two methods were highly correlated, reflecting dietary variation in a similar manner. Variation in PCR-DGGE data was more strongly correlated with the principal environmental gradient (distance from the opening to the Irish Sea), while values of δ 13C and δ 15N became progressively enriched, suggesting a greater dependence on animal tissue and benthic microalgae. Diatoms and crustaceans were the most frequently observed phylotypes identified by sequencing, but specific DNA results provided little support for the trophic trends observed in the stable isotope data. This combined approach offers an increased level of trophic insight for suspension feeders and could be applied to other organisms.

Uptake, accumulation, and biotransformation of metal oxide nanoparticles by a marine suspension-feeder

A growing body of evidence indicates that some engineered nanoparticles (ENPs) are toxic to organisms that perform important ecosystem services in terrestrial and aquatic ecosystems. However, toxicity can be influenced by the biotransformation of contaminants, including ENPs, as it may alter the fate and transport of these substances. In turn, fate and transport can influence their bioavailability. To understand how biotransformation influences the fate and transport of ENPs in marine ecosystems, we exposed suspension-feeding mussels, Mytilus galloprovincialis, to two common nano-metal oxides, CeO2 and ZnO, over a range of concentrations from 1mgL−1 to 10mgL−1, in a laboratory experiment. Mussels exposed to 10mgL−1 accumulated 62μgg−1 of Ce and 880μgg−1 of Zn on a dry tissue basis but rejected 21,000μgg−1 for Ce and 63,000μgg−1 for Zn in pseudofeces. Scanning electron microscope evidence indicates CeO2 remained as ENPs but ZnO did not after being rejected by the mussels. Mussels filtered most of the CeO2 from the aqueous media, while a significant fraction of Zn remained in solution. Differences in ENP solubility affect ENP uptake, excretion, and accumulation in mussels. Our study highlights the potential role of marine suspension feeders in biotransformation of ENPs.

Kelp as a trophic resource for marine suspension feeders: a review of isotope-based evidence

Kelp forests are enormously productive, and they and adjacent habitats support large populations of suspension feeders. What do these suspension feeders eat? Intuitively, we might expect that kelp primary production is a key form of trophic support for these animals. Indeed, a large and growing number of studies using carbon stable isotope data, typically collected over short time periods, have asserted that detritus from kelps is an important, and in some cases the main, food source for coastal benthic suspension feeders. This view has been incorporated into several textbooks and review papers covering kelp forest ecosystems, and loss of trophic support for benthic suspension feeders is now often invoked as an ecosystem consequence of top-down or other impacts on kelp forests. More direct evidence, however, suggests that these animals mainly eat phytoplankton and, in some cases, bacteria or zooplankton. Because isotope values of pure coastal phytoplankton, uncontaminated with detritus, are difficult to obtain, present studies have largely relied on single measurements from offshore environments or from the literature, which typically reflects offshore values. We review the evidence showing that phytoplankton isotope values can, and are expected to, vary widely in coastal waters and that inshore phytoplankton may often be enriched in 13C compared to offshore phytoplankton. This unaccounted-for variation may have systematically biased the results of such trophic studies toward finding large contributions of kelp detritus to suspension-feeder diets. We review some key stable isotope studies and put forth evidence for alternative explanations of the isotope patterns presented. Finally, we make recommendations for future isotope studies and describe several approaches for progress in this area. New techniques, particularly flow cytometry and compound-specific stable isotope analysis, provide ways to shed light on this interesting and important ecological issue.

Devonian Trace Fossils of the Horlick Formation, Ohio Range, Antarctica: Systematic Description and Palaeoenvironmental Interpretation

The clastic Horlick Formation contains an ichnofauna of 28 ichnotaxa dominated by burrowers. These are a mixture of simple vertical forms (Skolithos linearis, S. magnus, Bergaueria cf. langi, Rosselia socialis, Monocraterion isp.), U or arc-like forms (Diplocraterion parallelum, Arenicolites types A and B, Catenarichnus antarcticus, C. isp., aff. Lanicoidichna isp.), and complex, vertical spiral structures (Asterosoma isp., Spirophyton isp.). Horizontal burrows include Ancorichnus cf. capronus, Palaeophycus tubularis, and Psammichnites devonicus isp. nov. Surface traces comprise Haplotichnus isp., Cruziana problematica, C. rhenana, Rusophycus aff. carbonarius, R. isp., Protovirgularia rugosa, Lockeia ornata and cubichnia indet., while trackways include Diplichnites gouldi, D. isp., Maculichna? isp. and large imprints. The Horlick Formation (maximum 56 m) records an early Devonian transgression onto a deeply weathered land area that lay in the direction of Marie Byrd Land, spreading from the South Africa sector of Gondwana. Analysis of the trace fossils confirms their formation in near-shore to intertidal environments, with some ichnotaxa living close to the marine/fluvial boundary (e.g., Spirophyton, aff. Lanicoidichna, Cruziana problematica, Rusophycus aff. carbonarius, Maculichna?). The ichnofauna probably comprised a variety of marine suspension and deposit-feeding worms, shallow burrowing molluscs (bivalves and possibly bellerophontids) and several different types of arthropods, including trilobites.

Use of PCR-DGGE to investigate the trophic ecology of marine suspension feeding bivalves

Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) approaches have previously been used to characterize marine plankton communities, but have rarely been used to investigate the trophic ecology of marine organisms. Here we use PCR-DGGE to obtain complex dietary profiles (often >20 bands) of eukaryotic organisms ingested by various species of bivalves. Sequence-based identification of individual phylotypes revealed ingestion of diatoms, dinoflagellates and other groups of organisms consistent with their known feeding ecology. Simulta- neously profiling the seawater (plankton) allowed direct comparison to the dietary profiles. In Mytilus edulis, 50% of the detected plankton community was observed in the dietary profiles. Conversely, 34% of the phylotypes detected in the dietary profiles were not observed in seawater samples. Simi- larity-based cluster analysis of the dietary profiles from 6 sympatric species (4 epifaunal, 2 infaunal) of bivalves revealed a distinct, species-specific clustering pattern in 5 species, indicating a partial division of food based resources. Interestingly, both infaunal species investigated had dietary profiles that clustered not only at the species-specific level, but also as a distinct infaunal group. Trophic over- lap was also present as evidenced by multiple shared phylotypes across all species. Mimachlamys varia did not group in a species-specific manner, suggesting a more generalist feeding strategy. Together, these results demonstrate the utility of a PCR-DGGE approach to study the feeding ecology of marine bivalves. This method offers a fast and accurate way to investigate the trophic interactions of marine bivalves (and presumably other invertebrates) across both large spatial and temporal scales.

Evaluation of changes in nutrient composition during production of cross-linked protein microencapsulated diets for marine fish larvae and suspension feeders

Cross-linked protein capsules as a vehicle for delivery of nutrients to marine fish larvae and marine suspension feeders were investigated. The effects of the production process on both qualitative and quantitative changes in protein, lipid and micronutrient concentrations were evaluated. There were no changes in lipid concentration and only minor (but significant) differences in crude protein concentrations as a result of the encapsulation process. However, there was nearly a complete loss of water-soluble nitrogen during capsule production — almost 100% of the water-soluble protein was cross-linked and made insoluble and 79% of the TCA-soluble N was lost. Peptides and free amino acids were lost during the capsule washing stages, but except for a 100% loss of taurine, small changes in the amino acid profile were observed. There was more than 90% loss of water-soluble micronutrients such as thiamin, vitamin C and zinc during capsule production, and only minor increase in concentration of thiamin and zinc in the diet by increasing the levels of these minerals and vitamins were possible. The fat-soluble vitamin E was not affected by the production process and can be delivered at controlled concentrations, but vitamin A had loss ranging from 4–57% with increased inclusion of vitamin A. With the existing production protocol, the results suggest that cross-linked protein capsules are not suitable for the delivery of water-soluble nutrients to fish larvae and marine suspension feeders.

Evaluation of wax spray beads for delivery of low-molecular weight, water-soluble nutrients and antibiotics to Artemia

Culture of the early larval stages of many marine fish species is often characterized by high larval mortality and poor growth. Comparison of the nutritional composition of cultured live prey, such as species of rotifers and Artemia, with that of “natural” prey species, such as copepods, indicates possible deficiencies in essential micronutrients that could explain the poor performance of larvae fed on these cultured foods. Enrichment of live prey species by feeding them on artificial diets is difficult due to high leakage losses from microparticles in aqueous suspension. In this study, wax spray beads (WSB) consisting of bees wax, with or without a 5% w/ w extract of a synthetic marine phospholipid (mPHL), were evaluated for their potential for delivery of water-soluble micronutrients and the antibiotic oxytetracycline (OTC) to Artemia. The micronutrient mix consisted of amino acids, vitamins and trace minerals and was based on the nutritional composition of copepods. Leaching experiments indicated that nitrogen (N) retention of WSB containing the micronutrient mix rapidly declined in the first 5 to 10 min of suspension in seawater; however, subsequent N losses over a 2 h period occurred at much lower rates, resulting in overall N retention efficiencies of 44% and 24% for WSB prepared with either 100% wax or 95% wax/5% mPHL, respectively. Substantial losses of labile micronutrients, such as vitamin A, vitamin E, astaxanthin, selenium, vitamin C and thiamin, occurred during WSB preparation. Furthermore, production of peroxidation products and losses of astaxanthin were greater with beads containing 5% mPHL compared with beads prepared with 100% bees wax. Artemia ingested and broke down riboflavin-containing WSB prepared with 100% bees wax and liberated riboflavin was observed in their digestive systems. Artemia fed OTC-containing WSB prepared with 100% bees wax retained OTC after purging their guts of ingested WSB. WSB may be useful in delivering water-soluble substances to Artemia as well as other marine suspension feeders capable of breaking down these beads by mechanical or enzymatic processes. The advantage of using wax as the lipid carrier, compared with phospholipid and triacylglycerol lipid types, is that it is relatively inert and will less likely react with incorporated materials to produce peroxides or result in excessive contributions to the lipid nutrition of the target organism.

Transparent exopolymer particles (TEP) from marine suspension feeders enhance particle aggregation

Transparent exopolymer particles (TEP) are known to form from dissolved precursors released by phytoplankton and bacteria. Many benthic suspension feeders also have been shown to produce significant amounts of TEP under field and laboratory conditions. Although TEP from phyto- plankton have been implicated in enhancing aggregation and sedimentation of suspended material, the role of TEP from suspension feeders in aggregate formation is still unknown. In order to deter- mine if TEP produced by suspension feeders enhance the formation of marine aggregates, organic matter from actively feeding blue mussels Mytilus edulis and sea vases Ciona intestinalis held in recirculating chambers was collected. Control water was collected from chambers without animals. Animal-conditioned and control water were then mixed with 1 of 2 non-sticky particles (silica-amino beads or diatomaceous earth). The suspensions were transferred to 250 ml bottles, which were placed on a roller table to generate aggregates. Particle aggregation was quantified by examining the size distribution of particles over time by means of an electronic particle counter (particles between 6 and 90 μm), and by counting large (greater than ca. 100 μm) aggregates under a microscope at the end of the experiment. We found that significantly more aggregates formed in the animal-conditioned water than in control water after 48 h, for both species and both kinds of added particles. The number of large aggregates that formed was related to TEP concentration, and not related to total or dissolved organic carbon. Our results suggest that suspension feeders produce significant quantities of TEP that can enhance particle aggregation.

Complex microparticles for delivery of low-molecular weight, water-soluble nutrients and pharmaceuticals to marine fish larvae

Most currently available microparticulate artificial diets for rearing marine suspension feeders, including larval fish, are not effective in retaining low-molecular weight, water-soluble (LMWS) nutrients and other materials [Lopez-Alvarado, J., Langdon, C.J., Teshima, S., Kanazawa, A., 1994. Effects of coating and encapsulation of crystalline amino acids on leaching in larval feeds. Aquaculture 122, 335–346; Baskerville-Bridges, B., Kling, L.J., 2000. Development and evaluation of microparticulate diets for early weaning of Atlantic cod, Gadus morhua, larvae. Aquac. Nutr. 6, 171–182]. Rapid leaching losses occur as a result of high surface-to-volume ratios and the porosity of the matrix or walls of the particles [Langdon, C.J., 2003. Microparticle types for delivery nutrients to marine fish larvae. Aquaculture 227, 259–275]. In order to address this problem of high leakage losses, a novel complex particle type was developed consisting of LMWS incorporated in lipid beads that are then bound, with other nutrients, in a matrix of the water-insoluble protein zein. A spray method for preparing lipid beads was developed to increase the concentration of incorporated core material as well as to reduce losses due to leakage from beads suspended in water. It was possible to prepare lipid spray beads (LSB) that delivered 8.5% of their dry weight as glycine after 1-h suspension in water, resulting in free amino acid concentrations similar to those of commonly used live feeds for fish larvae, such as rotifers and Artemia; however, this delivery efficiency was reduced to 1.2% glycine for complex particles made up of 30% w/w glycine-containing LSB and other dietary nutrients. Further experiments are required to determine if complex particles can replace living feeds for the early larval stages of marine fish species.

Optical characteristics of suspended marine particles for short light pulses

Oceanological problems, which need the knowledge of peculiarities of pulse propagation in the sea, are analyzed. Optical characteristics of typical particles of marine suspension at pulse irradiation are calculated. It is shown that efficiencies for backscattering for the pulse and monochromatic wave differ markedly. For efficiencies for scattering and for extinction, these differences are much less noticeable. Reasons for these differences are explained.

The Phylogenetic Position of the Pterobranch Hemichordates Based on 18S rDNA Sequence Data

Pterobranchs are a class of deuterostome metazoans that are sessile marine suspension feeders. Although this group has been poorly studied, understanding their phylogenetic affinities is central to understanding early metazoan evolution. Sequence data from the 5′ end of the 18S rDNA gene was collected from a pterobranch, Rhabdopleura normani, and combined with other available 18S sequences. Using standard phylogenetic methods, the evolutionary relationships of deuterostome metazoans were reconstructed. The pterobranchs are most closely related to the enteropneust hemichordates. This was confirmed by bootstrap analyses and a topology-dependent cladistic permutation tail probability (T-PTP) test. My analysis agrees with Turbeville et al.′s (1994) and Wada and Satoh′s (1994) finding that hemichordates are more closely related to echinoderms than to chordates, and it is proposed that Metschnikoff′s (1881) name Ambulacraria be adopted for the clade defined by the last common ancestor of the hemichordates and echinoderms. These findings suggest that ciliated gill slits and the dorsal hollow nerve chord are pleisomorphic features of the Deuterostomia.