Sediment Ingestion Research Articles

The Role of Sediment Ingestion in Exposing Bottom-Feeding Fish to Chemical Elements.

Digesta were collected from the intestines of seven species of bottom-feeding fish to better understand the role of incidental ingestion of sediment in exposing fish to inorganic contaminants. A composite sediment tracer variable, based on concentrations of Co, Cr, Ni, Ti, V, and Y in digesta and in sediment, was calculated to estimate sediment content of digesta. Concentration factors (mg/kg in digesta divided by mg/kg in sediment) of eight elements of interest were linearly regressed on this tracer variable. The relative importance of sediment ingestion to oral exposure was quantified. Zinc, Cd, and Cu were ingested mainly from sediment-free food. Arsenic, Cr, Ni, Al, and Pb, in contrast, were ingested mainly from sediment. As an example, 93% of the Ni in digesta from a brown bullhead (Ameiurus nebulosus) was from sediment and only 7% from food. Regressions of Al and Pb in digesta of suckers (Catostomidae) suggested an additional oral source, possibly from oxides coating biotic or abiotic surfaces. Overall, concentrations of 12 of 21 elements studied were positively correlated with sediment content (p < 0.005). Including sediment ingestion as a pathway for bottom-feeding fish is essential for accurately estimating exposures in toxicological studies. Environ Toxicol Chem 2024;43:1036-1046. Published 2024. This article is a U.S. Government work and is in the public domain in the USA.

Sediment ingestion in the invasive apple snail Pomacea canaliculata

Sediment ingestion in the invasive apple snail Pomacea canaliculata

Numerical model reveals the potential factors of ingestion of fecal sediments by deep-sea deposit-feeding benthos: Implications for composite trace fossils

The occurrence of trace fossils reworked by Phycosiphon has increased since the Cretaceous. This ichnological record may suggest an effective feeding mode of the deposit-feeding Phycosiphon-producers because the organic carbon content of the burrow infill (especially of fecal origin) within the sediments is generally higher than that of the surrounding sediments. However, the exact factors which drove the Phycosiphon-producers to ingest the burrow infill buried within deeper sediments are unclear. Therefore, to clarify the factors, we constructed a new food selection model (PFF model) based on optimal foraging theory for deep-sea deposit feeders. We conducted numerical experiments using the appropriate set of parameters inferred from the actual geological data. The results indicate that, the increased amount and/or size of fecal sediments may have driven the ingestion of fecal sediments by small deposit-feeding benthos. Also, because trace fossils produced by deep-sea deposit-feeding benthos may have become larger since the Cretaceous, fecal sediments buried within deeper sediment may have behaved as an efficient feeding site for deep-sea deposit-feeding benthos since the Cretaceous onwards. Compiled data of composite trace fossils further supported our results of the numerical experiments. The PFF model constructed in this study will be applied to examine the phenomenon of feeding optimization of deep-sea deposit feeders by ingestion of fecal sediments throughout the Phanerozoic.

Bioaccumulation of per- and polyfluoroalkyl substances by freshwater benthic macroinvertebrates: Impact of species and sediment organic carbon content

Per- and polyfluoroalkyl substances (PFAS) in aquatic environments have caused global concern due to their persistence, toxicity, and potential bioaccumulation of some compounds. As an important compartment of the aquatic ecosystem, sediment properties impact PFAS partitioning between aqueous and solid phases, but little is known about the influence of sediment organic carbon content on PFAS bioaccumulation in benthic organisms. In this study, three freshwater benthic macroinvertebrates – worms (Lumbriculus variegatus), mussels (Elliptio complanata) and snails (Physella acuta) – were exposed for 28 days to PFAS spiked synthetic sediment equilibrated with a synthetic surface water. Using microcosms, sediment organic carbon content – 2%, 5% and 8% – was manipulated to assess its impact on PFAS bioaccumulation. Worms were found to have substantially greater PFAS bioaccumulation compared to mussels and snails. The bioaccumulation factors (BAFs) and biota sediment accumulation factors (BSAFs) in worms were both one to two magnitudes higher than in mussels and snails, likely due to different habitat-specific uptake pathways and elimination capacities among species. In these experiments, increasing sediment organic carbon content decreased the bioaccumulation of PFAS to benthic macroinvertebrates. In worms, sediment organic carbon content was hypothesized to impact PFAS bioaccumulation by affecting PFAS partitioning and sediment ingestion rate. Notably, the BSAF values of 8:2 fluorotelomer sulfonic acid (FTS) were the largest among 14 PFAS for all species, suggesting that the benthic macroinvertebrates probably have different metabolic mechanisms for fluorotelomer sulfonic acids compared to fish evaluated in published literature. Understanding the impact of species and sediment organic carbon on PFAS bioaccumulation is key to developing environmental quality guidelines and evaluating potential ecological risks to higher trophic level species.

Inputs don't equal outputs: bacterial microbiomes of the ingesta, gut, and feces of the keystone deposit feeder Ilyanassa obsoleta.

Bacteria drive energy fluxes and geochemical processes in estuarine sediments. Deposit-feeding invertebrates alter the structure and activity of microbial communities through sediment ingestion, gut passage, and defecation. The eastern mud snail, Ilyanassa obsoleta, is native to estuaries of the northwestern Atlantic, ranging from Nova Scotia, Canada, to Florida in the USA. Given extremely high densities, their deposit-feeding and locomotory activities exert ecological influence on other invertebrates and microbes. Our aim was to characterize the bacterial microbiome of this 'keystone species' and determine how its feeding alters the native bacterial microbiota. We gathered snails from both mudflat and sandflat habitats and collected their fresh fecal pellets in the laboratory. Dissection of these same snails allowed us to compare bacterial assemblages of ingested sediments, shell surfaces, gut sections (esophagus, stomach, intestine), and feces using DNA metabarcoding. Our findings indicate a diverse, resident gut microbiota. The stomach and intestines were dominated by bacteria of the genus Mycoplasma. Comparison of ingesta and feces revealed digestion of several bacterial taxa, introduction of gut residents during passage, in addition to unique bacterial taxa within the feces of unknown provenance. Our results demonstrate that I. obsoleta has the potential to modify microbial community structure in estuarine sediments.

A 3D perspective on sediment turnover and feeding selectivity in blennies

Sediments in algal turfs can modify a wide variety of key ecological processes on coral reefs. While some larger reef fishes can remove these turf-bound sediments, the role of small, yet abundant, cryptobenthic fishes is currently unclear. To address this knowledge gap, we explored the extent to which the blenny, Ecsenius stictus, can shape sediment dynamics on coral reefs by quantifying their sediment ingestion and space use. Per unit body mass, E. stictus process sediments at comparable rates to key parrotfish and surgeonfish species. However, in absolute terms, E. stictus has a negligible influence on net sediment dynamics, despite their abundance. Behavioural observations and 3D photogrammetry reveal that E. stictus preferentially feed and rest on elevated surfaces; potentially because of low sediment loads on these surfaces. Overall, E. stictus may be responding to sediment loads rather than manipulating them; it is a passenger rather than a driver in reef processes.

Sediment contamination by trace elements and the associated ecological and health risk assessment: A case study from a large reservoir (Turkey).

Although Keban Reservoir (KR) is Turkey's the second largest man-made reservoir, limited data are available on the contents of trace elements (TEs) in sediments of the KR. The concentrations of 23 less- and commonly-monitored TEs in the sediments from 49 sites in the reservoir were measured to assess health risks, contamination levels and ecological risks of TEs. Concerning median Enrichment Factor values of TEs, chromium (Cr), strontium (Sr) and nickel (Ni) showed moderate enrichment, while other TEs showed minimal enrichment. Pollution Load Index values ranged from 0.33 to 0.63, indicating no a multi-element contamination case in the study area. Low ecological risk was found at 47 sites, while moderate ecological risk was recorded at two sites. The PEC (probable effect concentration) values were exceeded for Ni and Cr. Although wastewater from leather processing factory partly contributed to Cr enrichment at site 2, all TEs mainly originated from lithogenic sources. Median hazard quotient (HQ) values of zirconium (Zr) and lanthanum (La) for children from sediment ingestion were above the risk threshold of unity (HQ=4.81 and 1.39) and contributed 62.9% and 18.2% of the total health risk. Such high HQ values of Zr and La have never been reported in the literature. Hazard index values for children exceeded those for adults, indicating that children are more vulnerable to health risks than adults. Carcinogenic risk values of arsenic (As) were within the acceptable limits. Our findings indicated that in a multi-element sediment study, some less-monitored elements such as Zr and La may have an important role in health risk assessment even if they are found in the sediment at low concentrations. Therefore, this study can be a model for future similar studies evaluating the health risks of multi-elements in sediments.

Bioavailability and trophic magnification of antibiotics in aquatic food webs of Pearl River, China: Influence of physicochemical characteristics and biotransformation

Information on trophodynamics of antibiotics and subsequent relationships to antibiotic metabolism in river ecosystem is still unavailable, limiting the evaluation of their bioaccumulation and trophodynamics in aquatic food webs. In the present study, concentrations and relative abundance of 11 antibiotics were investigated in surface water, sediment and 22 aquatic taxa (e.g., fish, invertebrates and plankton) from Pearl River, South China. The logarithmic bioaccumulation factors (log BAFs) of antibiotics generally showed positive relationships with their log D (pH-adjusted log Kow), implying that their bioaccumulation of ionizable antibiotics depends on it is in an ionized form. Higher BAFs of antibiotics in benthic biota were observed than those in fish, indicating that sediment ingestion was a possible route of antibiotic exposure. The logarithmic biota-sediment accumulation factors (log BSAFs) of benthic biota increased when log D increased from −4.79 to −0.01, but declined thereafter. Trophodynamics of antibiotics was investigated, and intrinsic clearance were measured in liver microsomes of Tilapia zillii (trophic level [TL]: 2.5), Anabas testudineu (TL: 3.9), and Coilia grayi (TL: 5.0). Only ciprofloxacin (CFX) showed significant trophic magnification (Trophic Magnification Factor [TMF] = 1.95), and a higher metabolism rate in lower trophic levels suggest that metabolic biotransformation play a significant role in driving biomagnification of antibiotics.

Numerical Model Reveals the Potential Factors of Ingestion of Fecal Sediments by Deep-Sea Deposit-Feeding Benthos: Implications for Composite Trace Fossils

Numerical Model Reveals the Potential Factors of Ingestion of Fecal Sediments by Deep-Sea Deposit-Feeding Benthos: Implications for Composite Trace Fossils

Environmental and Human Health Risk Assessment of Potential Toxic Elements in Sediments from Ebrié Lagoon, Côte d’Ivoire

Ebrie lagoon is one of the largest in the West Africa lagoon system and contributes to the social and economic well-being of the habitants. Whereas, the sectors IV and V of Ebrié lagoon are increasingly threatened by potential toxic elements (PTEs) pollution due to urban growth, and industrial and agricultural activities, but few studies have focused on the contamination of sediments by PTEs and the human health risks. In the present study, surface sediments from sectors IV and V of Ebrié lagoon were sampled for the geochemical, human risk and ecological risks assessment of four potential toxic elements (PTEs) (As, Cd, Hg and Pb). Results indicate that particle of grain size of > 63 µm (sand) were the most abundant in the surface sediments with relative high TOC content. However, particle size did not affect metals distribution in sediments. PTE mean concentrations did not exceed the UCC values. The geoaccumulation index and enrichiment factor values indicate that no Cd and Pb contamination has occured on the whole, but sediments have been polluted by As and Hg and suggest that Cd and Pb were influenced by from natural weathering processes, whereas As and Hg derived from anthropogenic inputs. The concentrations of Hg higher than PEC, which suggest that it may pose adverse effects to organisms. The results of this study indicated that As, Hg and Pb increase health risks via sediment ingestion for both chidren and adults. With regard to concentrations and level of risk, Hg is the most toxic metal that requires special attention including monitoring of pollution level, wastewater treatment for better environmental management in sectors IV and V of Ebrié lagoon.

Assessment of natural radionuclides and heavy metals contamination to the environment: Case study of Malaysian unregulated tin-tailing processing industry

The tin tailing processing industry in Malaysia has operated with minimal regard and awareness for material management and working environment safety, impacting the environment and workers in aspects of radiation and heavy metal exposure. RIA was conducted where environmental samples were analyzed, revealing concentrations of 226Ra, 232Th and 40K between the range of 0.1–10.0, 0.0–25.7, and 0.1–5.8 Bq/g respectively, resulting in the AED exceeding UNCEAR recommended value and regulation limit enforced by AELB (1 mSv/y). Raeq calculated indicates that samples collected pose a significant threat to human health from gamma-ray exposure. Assessment of heavy metal content via pollution indices of soil and sediment showed significant contamination and enrichment from processing activities conducted. As and Fe were two of the highest metals exposed both via soil ingestion with an average of 4.6 × 10−3 mg/kg-day and 1.4 × 10−4 mg/kg-day, and dermal contact with an average of 5.6 × 10−4 mg/kg-day and 6.0 × 10−4. mg/kg-day respectively. Exposure via accidental ingestion of soil and sediment could potentially cause adverse non-carcinogenic and carcinogenic health effect towards workers in the industry. Correlation analysis indicates the presence of a relationship between the concentration of NORM and trace elements.

Release of sediment metals bound by glomalin related soil protein in waterfowls inhabiting mangrove patches

Glomalin-related soil protein (GRSP) has received extensive attention due to its ability to immobilize metals in the environment. However, whether it can enter the food chain through digestion is still unclear. Mangroves occupy the transition zone between the sea and land, have important ecological functions. Mangroves suffer from fragmentation due to human activities and urbanization. A variety of waterfowls inhabit near the mangroves and ingest sediment settled on their food inadvertently or for grit; therefore, they are ideal for revealing GRSP's role in metal enrichment. In this study, we investigated the release of metals from mangrove surface sediments and GRSP through a physiologically based extraction test. The investigated metals (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in sediments and those bound to GRSP would be mainly released in the gizzard phase. GRSP appeared to be an efficient carrier of Cu, Zn, Pb, and As from sediments to the waterfowls via direct sediment ingestion. For instance, 3.21% and 3.34% of sediment Cu were released in the gizzard and intestinal phases, respectively, meanwhile GRSP-bound Cu contributed 5.04% and 5.42% to this flux. The continuum of GRSP enrichment - complexation of GRSP and metals - biological accessibility of GRSP-bound metals, influenced by both direct and indirect effects from major nutrients (e.g., C, N, P, and S) and metal contents (e.g., Cu, Cd, Ni), controlled the release of GRSP-bound metals during simulated digestion. Overall, this study provides new insights into the potential risk of GRSP acting as a metal delivery vehicle in the food chain.

Effects of benzo[a]pyrene exposure on black rockfish (Sebastes schlegelii): EROD activity, CYP1A protein, and immunohistochemical and histopathological alterations.

Cytochrome P450 1A (CYP1A) is the major phase I of metabolic enzyme that plays essential roles in the detoxification of drugs and biotransformation of environmental pollutants. This study investigated CYP1A enzyme induction using EROD activity, CYP1A protein levels, and immunohistochemistry, along with histopathology of the liver, gills, kidneys, and intestine from the black rockfish, Sebastes schlegelii, exposed to benzo[a]pyrene (B[a]P). S. schlegelii has high risks of ingestion of sediment and absorption of heavy crude oil after accidental oil spills in Korea. This study thus exposed fish to B[a]P at 2, 20, and 200 μg/g body weight. EROD activity and CYP1A protein levels in hepatic microsomes had a positive correlation with the concentration of B[a]P (2-200 μg/g); in particular, exposure to 200 μg/g of B[a]P resulted in a 4- and 6-fold increase in hepatic EROD activity and CYP1A protein level, respectively. Hyperplasia of primary lamellar epithelium and atrophy of renal tubules were observed in the gills and kidney, respectively, following exposure to B[a]P at 200 μg/g. In contrast, severe histological alteration was not seen in intestinal tissues. Immunohistochemical analysis of the distribution of cellular CYP1A in four tissues showed strong immunostaining in the cytoplasm and nuclear membranes of the liver against B[a]P at 200 μg/g. Polycyclic aromatic hydrocarbons (PAHs), such as B[a]P, cause adverse histological changes in tissues of fish and provide evidence that PAH metabolism is inducible in fish liver, leading to increased CYP1A induction. Furthermore, the CYP1A induction in specific tissues might assist in monitoring and field assessment of marine ecosystems.

Polychaete worm - A passive carrier for Enterocytozoon hepatopenaei in shrimp

The present study assessed the role of polychaetes as a potential carrier for transmission of Enterocytozoon hepatopenaei (EHP) in shrimp. The PCR based screening of wild polychaete samples (n = 330) along three coastal states of India revealed EHP in 7.6%, white spot syndrome virus (WSSV) in 8.5% and co-infection of WSSV and EHP in 3.6% samples. Out of 7.6% (n = 25), polychaetes tested positive for EHP by nested PCR assay, 2.1% were I step PCR positive (severe infections) and 5.5% nested step positive (light infections). About 75% of the EHP-positive polychaete samples originated from the sites surrounding or adjacent to shrimp farming areas. Phylogenetic analysis showed that EHP isolates from polychaetes clustered into a single group together with that from India and other countries. Challenge experiments using naïve polychaetes fed with faecal samples of EHP-infected shrimp became positive for EHP in 100% worms at 15 days. However, evidence on replication of EHP in polychaete tissues by histological studies is insufficient to confirm intracellular development. Similarly, EHP-positive polychaetes fed to naïve shrimp transmitted the infection to detectable levels by PCR within a week. The EHP-positive gravid worms did not transmit the microsporidian parasite to their progeny (fertilised eggs or different larval stages). The EHP has the potential to persist in wild polychaetes as long as the worms inhabit contaminated soil sediments. It could therefore be concluded that the polychaetes were apparently capable of carrying infectious spores for some period after ingestion of EHP-contaminated feed or soil sediments. The results support the popular view that use of wild-caught polychaetes as live-feed to shrimp broodstock can increase the risk of passive or mechanical transmission of EHP leading to contamination risk in hatcheries. The present work appears to be the first study involving experimental infection and transmission of E. hepatopenaei between shrimp and polychaetes, in either direction i.e., from shrimp to polychaetes and vice versa.

Ecological and probabilistic human health risk assessment of heavy metal(loid)s in river sediments affected by mining activities in Ecuador.

Gold mining is a significant source of metal(loid)s released into the environment. It is an issue of concern due to the potential adverse health effects associated with exposure to toxic elements. This study aimed to assess the ecological and human health risk caused by heavy metal(loid)s exposure in river sediments in Ponce Enríquez, one of the most important mining sites in Ecuador. Concentrations of As, Cd, Cu, Pb, and Zn were evaluated in 172 sediment samples to determine the Potential ecological risk (RI) and the carcinogenic (CR) and non-carcinogenic risk (HQ). The human exposure to polluted sediments during recreational activities was computed using Bayesian probabilistic models. Residents were randomly surveyed to adjust the risk models to the specific population data. More than 68% of the sampling stations pose a severe As and Cd ecological risk index ([Formula: see text] > 320). Likewise, residents exposed to river sediments showed a non-acceptable carcinogenic risk by incidental ingestion, being As the primary contributor to overall cancer in both children and adults receptors. Moreover, non-carcinogenic risk through the incidental ingestion of sediments was above the safe limit for children. This is the first study conducted in a mining region in Ecuador that reveals the severe levels of ecological and human health risk to which the population is exposed. These results can be applied as a baseline to develop public health strategies to monitor and reduce the health hazards of the residents of mining communities.

Sand grains in the stomach of brown shrimp, Crangon crangon: Crunchy garnish, supportive macerator, or simply dirt?

Brown shrimp, Crangon crangon, inhabit highly productive sandy and muddy grounds of the southern North Sea. The stomachs of the shrimp contain variable and often high numbers of sediment grains. The function of sediment grains inside the stomach and the purpose of their ingestion are only poorly understood. We tested in laboratory experiments whether sediment and associated organic material complement the natural food of C. crangon or if sand grains may be used by the shrimp to support trituration and maceration of ingested food. The shrimp showed no notable preference for sediment with natural organic content over sediment with reduced organic content, limited ingestion of sediment upon starvation, and no additional uptake of sand grains after feeding. Instead, C. crangon took up sediment only while feeding on regular food, suggesting that sand grains are not ingested intentionally but rather incidentally as a side effect of hasty gobbling. This conclusion is supported by the highly variable uptake of sand grains among individuals. Under experimental conditions, sand grains from sediments do not seem to have a crucial function in food processing and digestion in brown shrimp.

Prevalence and persistence of microcystin in shoreline lake sediments and porewater, and associated potential for human health risk

Midlatitude waterbodies are experiencing increased cyanobacteria blooms that necessitate health advisories to protect waterbody users. Although surface waters may contain cyanotoxins such as microcystin (MC), at concentrations that pose potential public health risks, little is known about MC contamination of shoreline sediments. Based on growing evidence that lake and reservoir sediments can accumulate MCs, we hypothesized that shoreline sediments (i.e., recreational beaches) may accumulate MCs and thereby pose a potential health risk to recreational users even if people stay out of contaminated water. We sampled nearshore surface water, shoreline sediment, and porewater from seven Washington State, USA, lakes/reservoirs recreational beaches to determine MC presence/absence during or immediately following cyanobacteria blooms. We found MCs in shoreline sediments at all waterbodies using ELISA and LC-MS/MS. MC concentrations in shoreline sediments and porewaters persisted for 20 days following dissipation of cyanobacteria blooms when MC concentrations were near analytical reporting limits in corresponding surface waters. A human health risk assessment based on potential MC exposure through incidental ingestion of porewaters and sediments found, even when very high MC concentrations occur in surface waters (i.e., >11,000 μg/L), estimated ingestion doses are below MC World Health Organization tolerable daily intake and U.S. Environmental Protection Agency’s risk reference dose. While our findings suggest MCs in Washington State recreational beaches in 2018 did not present a significant human health risk, future blooms with higher MC concentrations could pose human health risks via the shoreline sediment/porewater exposure pathway.

Ecological and Human Health Risk Assessment of Sediments near to Industrialized Areas along Langat River, Selangor, Malaysia

ABSTRACT Rapid industrialization at Kuala Langat, Selangor have raised environmental and health concerns among the public. Surface sediments from a total of 10 stations, covering the upstream and downstream sites near to plastic recycling factories along Langat River were collected and analyzed for its physicochemical properties, bioavailable heavy metals concentration and pollution degree. Ecological risk assessment of heavy metals was carried out using several pollution indices such as geoaccumulation index (), contamination factor (CF), contamination degree (CD), enrichment factor (EF), pollution load index (PLI) and potential ecological risk index (PERI). For human health risk assessment, non-carcinogenic risk of heavy metals (Cd, Cr, Cu, Pb and Zn) was assessed using hazard quotient (HQ) and hazard index (HI) whereas carcinogenic risk of heavy metals (Cd, Cr and Pb) was assessed using carcinogenic risk index (RI) and total risk (TR). The heavy metal accumulation in sediments in terms of concentration was in the order of Pb > Zn > Cu > Cr > Cd and the mean concentration of the heavy metals were lower than the background value except Pb. The PLI result indicated that the sediment at Langat River was unpolluted but posed low ecological risk by Cr, Cu and Zn, low to moderate ecological risk by Cd, and low to considerable ecological risk by Pb as shown by PERI result. However, non-dietary ingestion of sediment from Langat River showed possible risk of non-carcinogenic effects at certain sites whereas tolerable carcinogenic risk at almost all sites. Organic matter, silt, clay, pH and base saturation showed significant relationship with the heavy metals concentration, indicating the transformation and accumulation factor of heavy metals in river sediment. This study is important to increase the awareness of sediment pollution at Langat River and provide information to the stakeholders in Kuala Langat for future planning and policies to protect the local ecosystem and residents.

Experimental investigation of a trench weir with T-shaped bars

The most common type of diversion structure used in boulder streams is a trench weir. It is a simple structure built below the bed level of streams, and the top of it is covered with bottom rack. Bottom rack consists of bars of various shapes like circular, rectangle, T-shaped, etc. It is placed over the trench weir with a desired porosity to control sediment ingestion into trench. In this present study, T-shaped bars are used because sediment ingestion and maintenance in the bottom rack consisting of T-shaped bar shall likely too low as compared to the rounded bars and rectangular bars. As in previous studies, Garcia et al. (Water 10(1035):1–21, 2018a, Water 10(1699):1–21, 2018b) compared the blocking capacity of bottom intakes having circular bars with intakes having T-shaped bars, they claimed that circular bar is inefficient as compared to T-shaped bars. The present study is based on experimental investigation of trench weir consisting of T-shaped bars under free flow condition, and it was found that the coefficient of discharge decreases with an increase in clear spacing of rack, slope of bottom rack, specific energy of approach flow, Froude number and Reynolds number. An equation is also being proposed to calculate coefficient of discharge with a maximum error of ± 20%.

Bioturbation by the marine polychaete Capitella teleta alters the sediment microbial community by ingestion and defecation of sediment particles

Deposit-feeding benthic invertebrates are known to modify sediment structure and impact microbial processes associated with biogeochemical cycles in marine sedimentary environments. Despite this, however, there is limited information on how sediment ingestion and defecation by marine benthos alters microbial community structure and function in sediments. In the current study, we used high-throughput sequencing data of 16S rRNA genes obtained from a previous microcosm study to examine how sediment processing by the marine polychaete Capitella teleta specifically affects sediment microbiota. Here we show that both sediment ingestion and defecation by C. teleta significantly alters overall microbial community structure and function. Sediment processing by C. teleta resulted in significant enrichment of sediment microbial communities involved in sulfur and carbon cycling in worm fecal pellets. Moreover, C. teleta's microbiota was predominantly comprised of bacterial functional groups involved in fermentation, relative to microbiota found outside of the host. Collectively, results of this study indicate that C. teleta has the ability to alter microbial biogeochemical cycles in the benthic sedimentary environment by altering microbial assemblages in the worm gut, and in the sediment ingested and defecated by worms as they feed on sediment particles. In this sense, C. teleta plays an important role as an ecosystem engineer and in shaping nutrient cycling in the benthic environment.