Suspension-feeding Activity Research Articles

Spatially Explicit Estimates of In Situ Filtration by Native Oysters to Augment Ecosystem Services during Restoration

US west coast populations of the native Olympia oyster Ostrea lurida declined precipitously in the late nineteenth and early twentieth centuries and were often replaced by the non-native Pacific oyster (Crassostrea gigas) by the aquaculture industry. Recovery of native oyster ecosystem services derived from their suspension feeding activities (termed “filtration services” (FS)) often serves as a powerful incentive for restoration of populations of O. lurida along the US west coast despite uncertainty about the potential effects of their filtration activities on concentrations of suspended particulate matter. Here, we provide an improved FS model for O. lurida and C. gigas in Yaquina Bay, OR, that is based on both in situ feeding behavior and the complex hydrodynamics of the estuary. The total area and the order of locations chosen for oyster restoration in Yaquina Bay were examined to determine how oyster FS could be maximized with limited resources. These modeling efforts quantified estimates showing (1) native oysters, if restored in Yaquina Bay to historic levels, may contribute nearly an order of magnitude greater FS than previously estimated; (2) C. gigas contributes significantly greater FS than O. lurida, especially during the wet season; (3) FS provided by either species is highly dependent upon seasonal river forcing and salinity; (4) spatial variation in FS arises from the hydrodynamics of the system, uneven oysters distributions, and upstream pre-filtering. We found that spatially explicit models demonstrated the benefits of prioritizing restoration to areas with the greatest FS potential, rather than placing oysters randomly within historic habitats. Directing restoration in this manner used between 75% (dry season) and 60% (wet season) less of the restored area needed to achieve comparable FS with randomly placed oysters.

Combined effects of flow speed and sub-lethal insecticide exposure on predator-prey interactions between the California killifish and an infaunal polychaete.

Hydrodynamics and pollution affect estuarine populations, but their ecological effects have rarely been studied in combination. We conducted two laboratory experiments to quantify whether predator-prey interactions between California killifish, Fundulus parvipinnis, and the polychaete Polydora cornuta vary with flow speed and chlorpyrifos exposure. In one experiment, only F. parvipinnis was exposed to chlorpyrifos; in the other, only P. cornuta was exposed. The flume included a 300-cm2 area of sediment with 24 P. cornuta in a central patch (98 cm2). We videotaped groups of three killifish for 50 min at one of four flow speeds (6, 9, 12, or 15 cm/s) and recorded the proportion of bites directed at the prey patch. Unexposed killifish directed 70% of their bites at the prey patch at 6 cm/s, and prey-patch selection decreased as flow increased. Killifish exposed to chlorpyrifos directed 41% of their bites at the prey patch at 6 cm/s with reduced prey-patch selection relative to unexposed fish at 9 and 12 cm/s. At 15 cm/s, both exposed and unexposed fish displayed non-selective biting. Worms were videotaped to quantify their deposit- and suspension-feeding activities. Exposing worms to chlorpyrifos reduced total feeding activity by ~30%. Suspension feeding was more common at faster flow speeds, but the time worms spent suspension feeding relative to deposit feeding was unaffected by chlorpyrifos. No behavioral changes were noted in either species when the other was exposed to chlorpyrifos. This study highlights how hydrodynamic conditions can alter the relative importance of a toxicant's effects on predator-prey interactions.

Algal flux affects the clearance rates of recently metamorphosed freshwater mussels

Despite their role as ecosystem engineers, which is in large part a consequence of their suspension feeding activities, the early life history of unionid mussels is not well understood. We examined the suspension feeding rates (i.e., clearance rates, CR) of recently metamorphosed juvenile Lampsilis siliquoidea (1–4 week old), Lampsilis fasciola (1–3 week old), Villosa iris (2 week old), and Ligumia nasuta (1 week old) under ecologically relevant flux conditions in a recirculating racetrack flow chamber system. The range of velocities examined was determined experimentally using a permeameter containing riverbed material (63 μm to 6.5 cm diameter) in which juvenile mussels are thought to reside. The CR of the juvenile unionid species increased linearly with algal flux and the ranking of CR among species was V. iris > L. siliquoidea > L. nasuta > L. fasciola. CR also increased with the age (or size) of the mussel cohort but within a species CR increased non-linearly with shell length of the individual. These results provide new insight into the feeding abilities of recently metamorphosed juvenile mussels as well as potential threats to their growth and survival, which contributes to our understanding of their habitat requirements and may assist in the conservation of this imperiled taxon.

Caught in the act: phenotypic consequences of a recent shift in feeding strategy of the shark barnacle Anelasma squalicola (Lovén, 1844).

Anelasma squalicola is a barnacle found attached to deep-water lantern sharks of the family Etmopteridae and is the only known cirriped on fish hosts. While A. squalicola is equipped with mouth and thoracic appendages (cirri), which are used for suspension feeding in conventional barnacles, its attachment device (peduncle) appears to have evolved into a feeding device, embedded into the tissue of its host. Here we demonstrate, through comparisons of the feeding apparatuses between A. squalicola and conventional suspension-feeding barnacles, that mouthparts and cirri of A. squalicola are highly reduced, and incapable of suspension-feeding activities. We show that in conventional suspension-feeding barnacles strong symmetries exist within these vital trophic structures. In A. squalicola strong asymmetries are widespread, indicating that those structures have been uncoupled from natural selection. The digestive tract is consistently empty, suggesting that feeding via cirri does not occur in A. squalicola. In addition, comparisons of stable isotope ratios (δ13C and δ15N) between A. squalicola, its shark host, and a conventional suspending feeding barnacle indicate that A. squalicola is taking nutrition directly from its host shark and not from the surrounding water. Our results strongly indicate that this barnacle has abandoned suspension feeding and now solely relies on obtaining nutrition from its host by a de novo evolved feeding mechanism.

Role and Value of Nitrogen Regulation Provided by Oysters (Crassostrea virginica) in the Mission-Aransas Estuary, Texas, USA

Suspension-feeding activities of oysters impart a potentially significant benefit to estuarine ecosystems via reduction of water column nutrients, plankton and seston biomass, and primary productivity which can have a significant impact on human well-being. This study considered nitrogen regulation by eastern oysters Crassostrea virginica in the Mission-Aransas Estuary, Texas, USA, as a function of denitrification, burial, and physical transport from the system via harvest. Oyster reefs were estimated to remove 502.5 kg N km−2 through denitrification of biodeposits and 251.3 kg N km−2 in burial of biodeposits to sediments. Nitrogen is also physically transported out of the estuary via harvest of oysters. Commercial harvest of oysters in the Mission-Aransas Estuary can remove approximately 21,665 kg N per year via physical transport from the system. We developed a transferable method to value the service of nitrogen regulation by oysters, where the potential cost equivalent value of nitrogen regulation is quantified via cost estimates for a constructed biological nutrient removal (BNR) supplement to a wastewater treatment plant. The potential annual engineered cost equivalent of the service of nitrogen regulation and removal provided by reefs in the Mission-Aransas Estuary is $293,993 yr−1. Monetizing ecosystem services can help increase awareness at the stakeholder level of the importance of oysters beyond commercial fishery values alone.

Estimates of Particulate Organic Carbon Flowing from the Pelagic Environment to the Benthos through Sponge Assemblages

Despite the importance of trophic interactions between organisms, and the relationship between primary production and benthic diversity, there have been few studies that have quantified the carbon flow from pelagic to benthic environments as a result of the assemblage level activity of suspension-feeding organisms. In this study, we examine the feeding activity of seven common sponge species from the Taputeranga marine reserve on the south coast of Wellington in New Zealand. We analysed the diet composition, feeding efficiency, pumping rates, and the number of food particles (specifically picoplanktonic prokaryotic cells) retained by sponges. We used this information, combined with abundance estimates of the sponges and estimations of the total amount of food available to sponges in a known volume of water (89,821 m3), to estimate: (1) particulate organic carbon (POC) fluxes through sponges as a result of their suspension-feeding activities on picoplankton; and (2) the proportion of the available POC from picoplankton that sponges consume. The most POC acquired by the sponges was from non-photosynthetic bacterial cells (ranging from 0.09 to 4.69 g C d−1 with varying sponge percentage cover from 0.5 to 5%), followed by Prochlorococcus (0.07 to 3.47 g C d−1) and then Synechococcus (0.05 to 2.34 g C d−1) cells. Depending on sponge abundance, the amount of POC that sponges consumed as a proportion of the total POC available was 0.2–12.1% for Bac, 0.4–21.3% for Prochlo, and 0.3–15.8% for Synecho. The flux of POC for the whole sponge assemblage, based on the consumption of prokaryotic picoplankton, ranged from 0.07–3.50 g C m2 d−1. This study is the first to estimate the contribution of a sponge assemblage (rather than focusing on individual sponge species) to POC flow from three groups of picoplankton in a temperate rocky reef through the feeding activity of sponges and demonstrates the importance of sponges to energy flow in rocky reef environments.

Ichnological constraints on the depositional environment of the Sawahlunto Formation, Kandi, northwest Ombilin Basin, west Sumatra, Indonesia

A low diversity trace fossil assemblage is described from the Oligocene Sawahlunto Formation near Kandi, in the northwestern part of the Ombilin Basin in western Sumatra, Indonesia. This trace fossil assemblage includes six ichnogenera attributed to invertebrate infaunal and epifaunal activities ( Arenicolites, Diplocraterion, Planolites, Monocraterion/ Skolithos and Coenobichnus) and two ichnotaxa attributed to vertebrate activity (avian footprints: two species of Aquatilavipes). Arenicolites, Diplocraterion and Monocraterion/ Skolithos record the suspension feeding activities of either arthropods (most likely amphipods) or vermiform organisms. Planolites reflects the presence of an infaunal deposit feeder. Coenobichnus records the walking activities of hermit crabs. Both the Coenobichnus and the avian footprints record the surficial detritus scavenging of epifaunal organisms within a subaerial setting. These traces occur within a fine-grained sandstone succession characterized by planar laminae and low-relief, asymmetrical, commonly mud-draped (locally bidirectional) ripples. The presence of traces attributable to suspension feeders implies deposition in a subaqueous setting. Their occurrence (particularly the presence of Arenicolites and Diplocraterion) in a sandstone bed characterized by mud-draped and bidirectional ripples implies emplacement in a tidally-influenced marine to marginal marine setting. Co-occurrence of these traces with well-preserved avian footprints ( Aquatilavipes) further implies periodic subaerial exposure. Thus, it is most likely that the Sawahlunto Formation near Kandi records deposition within an intertidal flat setting. Definitive evidence of marine influences in the Oligocene interval of the Ombilin Basin implies a more complex tectono-stratigraphic history than has previously been implied.

Wave-influenced deltaic sandstone bodies and offshore deposits in the Viking Formation, Hamilton Lake area, south-central Alberta, Canada

Abstract Subtle indications of deltaic influence can be overlooked in coarsening-upward units that resemble shoreface successions such as those found in the Cretaceous Viking Formation at Hamilton Lake (HL). Particular facies within HL strata contain physical and biogenic indicators of riverine discharge, and are interpreted as deltaic in origin. This study focuses on distinguishing between these deltaic deposits and strata reflecting normal-marine depositional conditions and relating facies within the stratigraphic framework. Based on detailed facies analysis, Viking deposits include: delta front, prodelta, upper offshore, lower offshore, shelf, slump and transgressive lag deposits. The principal group of facies, Facies Association 1 (FA1), is interpreted as deltaic in nature, which is indicated by evidence of: high sedimentation rates, salinity fluctuations, riverine discharge, hypopycnal and hyperpycnal flows, and moderately to subtly stressed ichnological suites. Trace fossil suites indicate suppression of suspension-feeding activities despite the presence of hummocky cross-stratified units that resemble shoreface deposition. Filter-feeding organisms are typically abundant in shoreface and wave-dominated deltaic successions. In the case of HL strata, hindrance of dwellings of inferred suspension-feeding animals in FA1 is attributed to increased water turbidity and suspended sediment associated with deltaic outflow. The presence of a restricted suite of structures of inferred suspension-feeders is uncharacteristic of river-dominated deltaic units, which are primarily reworked by deposit feeders. Accordingly, sedimentological evidence in combination with the proportion of dwellings of inferred suspension-feeders signifies moderate wave mitigation of environmental stresses induced by riverine discharge indicative of a wave-influenced deltaic system. In contrast to FA1, muddy sandstones to sandy mudstones of Facies Association 2 contain abundant and diverse suites of trace fossils interpreted to reflect deposition in the distal lower shoreface to upper offshore. Facies Association 3 is predominantly comprised of sandy mudstones with varying degrees of bioturbation indicative of lower offshore, shelfal, slump and transgressive lag deposits. The depositional history at HL includes periods of progradation alternating with transgressive flooding, subaerial exposure, stillstand progradation and wave ravinement. Four major bounding discontinuities and two major transgressive flooding surfaces separate units reflecting predominantly deltaic deposition, strictly offshore deposition, and mixed offshore and deltaic deposition. Variation in the deltaic and normal-marine signature of the deposits suggests changes in source area(s) over time, shifting shore-parallel deltaic influence, or fluctuations in riverine influx.

Influence of self-organised structures on near-bed hydrodynamics and sediment dynamics within a mussel ( Mytilus edulis) bed in the Menai Strait

The impacts of natural mussel assemblages on near-bed hydrodynamics, sediment erosion and deposition were quantified in flume studies. Mussels were sampled from a site in the Menai Strait (North Wales), together with field measurements of hydrodynamics over the tidal cycle (water depth, current speeds, turbulent kinetic energy (TKE)). Bare sediment (within a mussel bed but 1.5 m from mussels) was very stable due to the influence of microphytobenthos (critical erosion velocity ( U crit) = 0.49 m s − 1 ; critical bed shear stress ( τ e) = 0.4 Pa). Sediment associated with 55% and 95% mussel coverage was more easily eroded ( U crit = 0.18 and 0.21 m s − 1 ). This was primarily due to the mussels enhancing near-bed TKE, and thus bed shear stress ( τ 0), which resulted in τ e values (0.5 and 0.7 Pa, respectively), slightly higher than the bare sediment (0% cover). Consequently, mussel assemblages induced resuspension of sediment and microphytobenthos at significantly lower current speeds, within the range recorded in the field. Flume simulated sinusoidal current cycles confirmed the influence of mussels on erosion thresholds for microphytobenthos and sediment with accelerating currents. Mussel suspension feeding activity enhanced the rapid clearance of particles from the water column (deposition) after the onset of decelerating currents. The results support the hypothesis that self-organised structures (mussel strings) enhance near-bed turbulence and the resuspension of microphytobenthos under moderate flows conditions (< 0.3 m s − 1 ). Thus self-organised mussel beds enhance the provision of food through resuspension that serves to offset the depletion of phytoplankton in the water column immediately above mussel beds.

Feeding response of the polychaete Sabellaria alveolata (Sabellariidae) to changes in seston concentration

Sabellaria alveolata is a tube-building gregarious polychaete that constructs large biogenic reefs. In macrotidal shellfish ecosystems, this species competes for food with cultivated suspension-feeders. The suspension-feeding activity and clearance rate of S. alveolata were investigated in response to changes in seston concentration. A flow-through system was designed to study 225 cm 2 reef blocks with more than 500 individuals. The experimental conditions were characterized by increasing concentrations of suspended particulate matter ranging from 6.5 to 153.8 mg L − 1, while the organic content of the diet (microalgae Skeletonema costatum) decreased inversely from 49 to 9%, to mimic the dilution of organic matter by inorganic particles, characteristic of tidal resuspension. We showed that the clearance rate exponentially decreased in relation to an increase in SPM concentration. Clearance rate was estimated at 5.3 10 − 3 L h − 1 or 0.93 L h − 1 g − 1 (dry weight) for the lowest seston concentration (SPM = 6.5 mg L − 1 ) and reached the asymptote at CR = 1.97 10 − 3 L h − 1 or 0.35 L h − 1 g − 1 (dry weight) when SPM exceeded 45 mg L − 1 . Using picture analyses of polychaete movements, we showed that, paradoxically, an increase in SPM concentration did not adversely affect the feeding activity of S. alveolata since the number of filtering individuals remained stable from SPM = 6.5 to 55.5 mg L − 1 . These values were applied at the scale of the bay of Mont-Saint-Michel (France) to demonstrate that the filtration pressure of large populations of wild suspension-feeders should not be underestimated when the carrying capacity has to be assessed in the context of increasing bivalve cultures.

Grazing effect of the invasive reef-forming polychaete Ficopomatus enigmaticus (Fauvel) on phytoplankton biomass in a SW Atlantic coastal lagoon

In this work we evaluate the potential grazing impact of the invasive reef-forming polychaete Ficopomatus enigmaticus in a SW Atlantic coastal lagoon (Mar Chiquita coastal lagoon; 37° 40' S, 57° 23' W; Argentina). This gregarious species feeds on suspended detritus and phytoplankton. Given the large area dominated by reefs, suspension feeding by this species might reduce the lagoon phytoplankton concentration and even hinder local eutrophication. To evaluate this hypothesis in situ replicated mesocosm experiments were performed in spring 2005 and, summer and winter 2006. Mesocosms enclosing reefs and without reefs were installed and grazing intensity was measured as the difference in chlorophyll a concentration and turbidity between the reef-treatment and the treatment without reefs. Reefs of F. enigmaticus decreased the mean chlorophyll a concentration, more during summer (56% decrease) than spring (25% decrease) and winter (19% decrease). Reefs also decreased water turbidity during summer (54% decrease) and spring (23% decrease). While previous studies indicate that the physical structure of these reefs alters water flow increasing water turbidity, our evidences show that their suspension-feeding activity can counteract this effect. Water turbidity was positively correlated with chlorophyll a concentration, which suggests that phytoplankton grazing by F. enigmaticus decreased light attenuation through the water column, with a potential for enhancement of benthic primary productivity. Therefore, our results suggest that grazing by this polychaete affects overall estuarine primary production as well as the relative importance of planktonic and benthic carbon sources to higher trophic levels.

Impacts of two introduced suspension feeders in Port Phillip Bay, Australia

In the past decade there has been a rapid increase in the study of the ecological consequences of marine invasions, but we still have data for only a small proportion of established marine invaders. This is exemplified by Port Phillip Bay, Australia, for which we have quantitative data on the impacts of only a handful of the >160 introduced and cryptogenic species present. Some of the most conspicuous of these invaders are the large epibenthic suspension feeders living on soft sediments. In this study, we examined the impact of 2 of the most common epibenthic suspension feeders in Port Phillip Bay, the introduced polychaete Sabella spallanzanii and an introduced solitary ascidian, Styela clava, by manipulating their densities in the field across the range of naturally occurring densities. Because of their physical presence at the sediment–water interface and suspension feeding activities, we predicted varying impacts across different macrofaunal groups (suspension feeders, deposit feeders, recruits and mobile species). These predictions were not supported for either introduced species despite good power. For individual taxa, there was a significant negative relationship between Sabella density and the abundance of lumbrinerid polychaetes and gammarid amphipods, and between Styela density and the abundance of lumbrinerids, tanaids, crustaceans as a group, and the bivalve Laternula rostrata. Nonetheless, these taxa only represent a small proportion of those present, and importantly, the effects generally emerged at Sabella and Styela densities (>1 to 2 ind. m–2) greater than those typically recorded on Port Phillip Bay sediments. Therefore, we suggest that the effects of Sabella and Styela on soft sediment assemblages in Port Phillip Bay are likely to be negligible.

Ophiomorpha irregulaire, rare trace fossil in shallow marine sandstones, Cretaceous Atane Formation, West Greenland

Ophiomorpha irregulaire is a large and extremely rare trace fossil. The type section is in the Book Cliffs, Utah, USA. A second on-shore locality is reported here, in the Nuussuaq Basin of West Greenland. Both occurrences date from the Late Cretaceous. Other reports of O. irregulaire are restricted to two-dimensional sections in well cores and are mostly Jurassic in age. The West Greenland occurrence is in the Atane Formation in shallow marine clean sandstone. The two on-shore localities lie in the same biogeographical region, in connection with the Cretaceous Western Interior Seaway of North America. O. irregulaire is characterized by a sinuous, branched meander maze lying mostly within a single horizontal plane, probably not far beneath the seafloor. The burrow lining has remarkably elongate pellets that probably were emplaced by the burrower. In some cases, diagenetic compression may have deformed the lining pellets to produce their elongated shape. The muddy sediment comprising the lining is almost unrepresented in the clean sands of the substrate, and it was probably trapped from suspension during suspension-feeding activity.

Feeding responses of the gastropod Crepidula fornicata to changes in seston concentration

We investigated the response of the suspension-feeding activity of the prosobranch gastropod Crepidula fornicata (L.) to changes in seston abundance and composition, characteristic of the natural particle variability experienced by suspension-feeding organisms as a consequence of tidal resuspension. The experimental conditions were characterized by seston concentrations (12.2 to 196.0 mg 1 -1 ) inversely related to the organic content of particulate matter (56 to 6%). The organic fraction was composed of 2 benthic diatoms, Entomoneis pseudoduplex (Smith) and Nitzschia aurariae (Cholnoky). Inorganic matter was composed of 2 to 3 μm diameter kaolinite particles. The functional unit used for determination of ecophysiological responses was a chain of 6 individuals with mean chain dry tissue weight of 1.05 g. The efficiency of particle retention as a function of particle size increased with increasing particle size from 2 to 4 μm (equivalent spherical diameter). Above 4 μm, all particles were cleared from suspension with 100% efficiency, but retention efficiencies of smaller particles significantly declined with increasing seston loads. A constant clearance rate (CR) was found throughout the seston range, with a mean of 0.76 ± 0.05 1 h -1 g -1 (±SE). Filtration rate increased linearly with seston concentration from a minimum value of 10 mg h -1 g -1 to a maximum of 42.8 mg h -1 g -1 at the highest concentration. The total biodeposition rate (sum of pseudofaeces and faeces) followed a similar linear trend, with an increase from 3.8 to 41.6 mg h -1 g -1 at the highest concentration. Absorption rate was very stable throughout the range of suspended particulate matter concentrations tested with a mean of 4.9 ± 0.5 mg h -1 g -1 (±SE). It was not possible to ascertain pre-ingestive selection, even though the organic content of biodeposits and diet was very similar. The low retention efficiency of small inorganic particles at high seston loads was the sole mechanism that was clearly identified in this study as counteracting food dilution by inorganic material, through the enrichment of the organic content of filtered matter. The absence of pre-ingestive selection in C. fornicata would increase the physiological significance of this process in turbid environments.

Feeding Behavior of the Porcellanid Crab Allopetrolisthes Spinifrons, Symbiont of the Sea Anemone Phymactis Papillosa

Abstract The porcellanid crab Allopetrolisthes spinifrons, a symbiont of the sea anemone Phymactis papillosa, shows a suspension-feeding behavior related to flow oscillations (repetitive changes of flow direction). Individual crabs oriented their filter appendages (third maxillipeds) to maintain a concave face upstream, showing a higher frequency of maxilliped movements (flexion) at the start of inverted flow. The crab is primarily a suspension feeder that can ingest host mucus and feces. Contrary to free-living porcellanids, the symbiotic life-style offers access to exposed sites in the intertidal and subtidal environments that are favorable for passive suspension-feeding activities and consequently, an alternative feeding mechanism is not necessary.

Particle removal rates by the mud shrimp Upogebia pugettensis, its burrow, and a commensal clam: effects on estuarine phytoplankton abundance

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 269:223-236 (2004) - doi:10.3354/meps269223 Particle removal rates by the mud shrimp Upogebia pugettensis, its burrow, and a commensal clam: effects on estuarine phytoplankton abundance Blaine D. Griffen1,*, Theodore H. DeWitt2, Chris Langdon3 1Zoology Department, University of New Hampshire, 46 College Road, Durham, New Hampshire 03878, USA 2National Health and Environmental Effects Laboratory ‹ Western Ecology Division, US Environmental Protection Agency, Newport, Oregon 97365, USA 3Coastal Oregon Marine Experiment Station and Department of Fish and Wildlife, Oregon State University, Hatfield Marine Science Center, Newport, Oregon 97365, USA *Email: bgriffen@cisunix.unh.edu ABSTRACT: The burrowing shrimp Upogebia pugettensis is an abundant intertidal invertebrate of Pacific Northwest, USA bays and estuaries where it lives commensally with the bivalve Cryptomya californica. Suspension-feeding activities by the shrimp and by its commensal clam, as well as particle settlement within the burrow, represent 3 different components that could remove phytoplankton from water drawn into shrimp burrows. These 3 components together comprise what we call the ŒU. pugettensis shrimp-burrow complex¹. In laboratory experiments, we measured particle removal by each of these components. Our results indicated that U. pugettensis itself is responsible for filtering the majority of phytoplankton removed by the U. pugettensis shrimp-burrow complex at phytoplankton concentrations of 0.12 mg C l-1, with filtration by C. californica becoming increasingly important at phytoplankton concentrations of 0.48 mg C l-1. Particle settlement in the burrow and adhesion to the burrow wall may also be responsible for removal of substantial proportions of phytoplankton. Using results from both laboratory and field experiments, we developed a population filtration model to examine the potential impacts of U. pugettensis shrimp-burrow complexes on phytoplankton in the Yaquina estuary, Newport, Oregon, USA. We showed that U. pugettensis shrimp-burrow complexes in this estuary may be capable of daily filtering the entire body of overlying water. We also examined the potential for food competition between U. pugettensis and other suspension feeders that are found in shrimp habitats, represented in this study by the Pacific oyster Crassostrea gigas. Comparison of retention efficiencies of shrimp and oysters indicated that they are both capable of utilizing phytoplankton-sized particles with similar efficiencies and, therefore, may compete for food when phytoplankton abundance is growth-limiting. KEY WORDS: Suspension feeding · Burrowing shrimp · Upogebia pugettensis · Cryptomya californica · Yaquina Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 269. Online publication date: March 25, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Benthic-pelagic exchange of microalgae at a tidal flat. 1. Pigment analysis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 196:59-73 (2000) - doi:10.3354/meps196059 Benthic-pelagic exchange of microalgae at a tidal flat. 1. Pigment analysis Cathy H. Lucas1,*, John Widdows2, Mary D. Brinsley2, Peter N. Salkeld2, Peter M. J. Herman3 1School of Ocean and Earth Science, University of Southampton, Southampton Oceanography Centre, European Way, Southampton SO14 3ZH, United Kingdom 2Centre for Coastal and Marine Sciences, Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, United Kingdom 3Netherlands Institute of Ecology (NIOO-CEMO), PO Box 140, 4400 AC Yerseke, The Netherlands *E-mail: catherine.h.lucas@soc.soton.ac.uk ABSTRACT: Annular flume experiments and high-performance liquid chromatography (HPLC) were used to quantitatively and qualitatively measure benthic-pelagic exchange of microphytobenthos from natural sediments. Clear spatial and temporal differences in microphytobenthos resuspension in response to stepwise increases in current velocity were observed. Resuspension of chlorophyll a (chl a) from sandy sediments containing low levels of microphytobenthos biomass (<11.5 mg chl a m-2) occurred gradually and continuously over a range of current velocities from 10 to 40 cm s-1. In June, well-developed diatom mats at siltier sites (>56 mg chl a m-2) displayed strong resistance to erosion at currents <20 to 25 cm s-1, above which there was a very rapid increase in the amount of chl a in suspension following the stripping of the algal mat from the sediment surface. In September, when the diatom bloom was over, these sediments were less resistant to erosion and resuspension of microalgae occurred at current velocities above 15 to 20 cm-1. Site 1, situated at the edge of the flat, had a dense algal mat but low sediment stability. Microalgae were readily resuspended because the extracellular polymeric substances (EPS) produced by the migratory diatoms were unable to consolidate during the short emersion period. As a rule more chl a was resuspended from sandy sediments at current velocities 15 and 20 cm-1, but above this current velocity chl a resuspension was greater from silty sediments. Although sandy sites have low biomass in the surface layer, the greater depth of sediment erosion during bedload transport exposes more chl a to the surface. The percentage of sedimentary chl a lost at selected current velocities was estimated, and the implications for carbon supply to the pelagic and benthic systems discussed. Much of the biomass resuspended may be deposited locally, particularly in sandier regions. During the flume experiments it was observed that settling of fine sediment and microalgae was extremely rapid, because it was being biodeposited by suspension-feeding activity, and Œstripped¹ out of the water column by rapidly sinking suspended particulate matter (SPM). Qualitative changes in suspended material were measured as % chl a (chl a/phaeopigments x 100%) and accessory pigment content. As current velocity increased the relative proportion of phaeopigments increased, which has important implications for benthic suspension feeders feeding in the benthic boundary layer. The findings from the flume experiments have been compared with in situ measurements of current velocity, SPM and chl a. KEY WORDS: Microphytobenthos · Resuspension · Deposition · Chlorophyll a · Accessory pigments · HPLC · Annular flume Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 196. Publication date: April 18, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Comparative physiological energetics of two suspension feeders: polychaete annelid Lanice conchilega (Pallas 1766) and Pacific cupped oyster Crassostrea gigas (Thunberg 1795)

Feeding competition between the Pacific cupped oyster Crassostrea gigas and the polychaete Lanice conchilega was studied by assessing the polychaete suspension feeding activity. Retention efficiency was estimated by comparing particle size distributions at the output of experimental chambers containing the species and controls. Although particles ranging from 4 to 12 μm were collected by L. conchilega, no upper threshold or maximum retention rate was reached within this range. In contrast, C. gigas showed retention starting at 2 μm, and reaching an upper threshold at 6 to 8 μm. Based on our results, feeding competition is likely to occur between C. gigas and L. conchilega. Standardised filtration rates reached 0.225 l h −1 g dmw −1 (±0.08) for L. conchilega and 2.43 l h −1 g dmw −1 C. gigas for animals of 1 g dry meat weight (dmw). Assimilation rates, 0.44 for L. conchilega and 0.49 for C. gigas, were similar for the two species. Respiration rates were estimated at 0.113 and 0.68 ml O 2 h −1 for L. conchilega (Allometric coefficient=0.534) and C. gigas respectively. Therefore polychaete scope for growth (SFG) (4.01 J h −1 g dmw −1) was significantly lower when compared with C. gigas SFG (61.96 J h −1 g dmw −1). The impact of the L. conchilega population on that of cultivated oysters was evaluated from these results and field population assessment of both species. Based on field population estimates, L. conchilega was responsible for a 19% decrease in the carrying capacity and 30% of the oxygen depletion from the total activity of both species. However, L. conchilega SFG was only 16% of that of the C. gigas population. Several hypotheses regarding population interactions are discussed.

Infection characteristics of Himasthla elongata cercariae in cockles as a function of water current

Digenean trematodes are widespread parasites of marine fauna. The first intermediate host of Himasthla elongata (Echinostomatidae) is the periwinkle Littorina littorea. The second host is less specific, as it includes various bivalve species. The definitive host is a waterbird. The free-living cercaria acts to ensure transmission from the first and second intermediate hosts. We examined the impact of water flow (still and running water) and host size (6-8, 8-10, 10-12 mm shell length classes) on the settling success of H. elongata cercariae in the second intermediate host by utilizing the common cockle Cerastoderma edule. Under 2 scenarios (free-stream velocity of 0 and 6 cm s-1) more than 90% of the experimental population of cockles (90 individuals per replicate) acquired infections and 60% of the added cercariae were recovered as metacercariae in cockle tissue (mainly foot and siphons). Infection intensity increased significantly with cockle size. Considering the filtering capacity of cockles, the dimension of the flume, and the flow velocity, a passive infection mechanism is proposed based on the suspension feeding activity of the host organism. The scale of potential dispersal of H. elongata is at least a few hundred metres.

Suspension-feeding activity of a dense Ophiothrix fragilis (Abildgaard) population at the water-sediment interface: Time coupling of food availability and feeding behaviour of the species

Ophiothrix fragilis is a suspension-feeder which forms dense aggregations (up to 2000 individuals m −2) in the Dover Strait. Its optimal suspension-feeding activity is expressed when currents are less than 20 cm s −1. Thus, the duration of this behaviour over a tidal cycle depends on the tidal velocity, and can be very short during spring tides. During neap tides, suspension-feeding is almost continuous but the flux of nutrients (phytoplankton, organic carbon and nitrogen) remains low because current increases slowly after slack water, and resuspension phenomena do not occur. In contrast, during spring tides, the current speed rapidly increases and induces an important resuspension of particles. Thus, the flux of nutrients is very important during the short duration of suspension-feeding of the O. fragilis population. Minimum gut contents were observed 3 h before slack current and maximum gut contents were observed about 1 h after slack water.