Density-dependent effects of bioturbation by the clam, Scrobicularia plana, on the erodibility of estuarine sediments

2009 ◽  
Vol 60 (7) ◽  
pp. 737 ◽  
Author(s):  
Claudia Soares ◽  
Paula Sobral
Keyword(s):  
Water Column ◽  
Chlorophyll A ◽  
Extracellular Polymeric Substance ◽  
Feeding Behaviour ◽  
Estuarine Sediments ◽  
Tagus Estuary ◽  
Benthic Organisms ◽  
Sediment Properties ◽  
Density Dependent ◽  
Scrobicularia Plana

Benthic organisms are known to modify sediment properties and influence the flux of materials to the water column. In this study, the density-dependent effects of bioturbation by the estuarine clam, Scrobicularia plana, on the biogeochemical properties and erodibility of the sediment were assessed using laboratory annular flumes. Sediments with different mud contents (~98% and 90%) were collected undisturbed from two different sites of the Tagus estuary. S. plana were added to the sediment at increasing densities (0, 57, 115 and 229 ind m–2) and left to bioturbate the sediment before the experimental erosion runs. All erosion runs were carried out following a stepwise increase of current velocities (U) up to 0.25 m s–1. Sediment chlorophyll a, pheopigments and extracellular polymeric substance fractions were measured at the time of sampling in the field and in the end of the erosion runs. Increasing densities of S. plana in the muddier sediment raised eroded mass, while the sediment with less mud behaved as non-cohesive and registered a decrease in eroded mass possibly due to a switch in the feeding behaviour of S. plana.

1.  Toxicity of Fresh and Weathered Sunken Heavy Fuel Oil to the Early Life Stages of Rainbow Trout (Oncorhynchus mykiss) in Simulated Spawning Shoal Environments

2016 ◽  
Author(s):  
Julie Adams
Keyword(s):  
Rainbow Trout ◽  
Water Column ◽  
Aquatic Organisms ◽  
Fuel Oil ◽  
South American ◽  
Benthic Organisms ◽  
Heavy Fuel Oil ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Direct Exposure ◽  
Insight Into

Because the density of heavy fuel oil (HFO) is equal to or greater than that of freshwater, it behaves differently than lighter oils that float. Heavy fuel oil can sink to the bottom or be suspended in the water column and affect aquatic organisms that are not typically exposed to floating oils. Most research on oil spill technologies thus far examines the direct exposure of rainbow trout to floating or submerged oil droplets; there is little knowledge of the impacts of non‐floating heavy fuel oil on the water column and benthic organisms exposed to oil that accumulates in sediments. The toxicity of sunken HFO 6303 and Medium South American (MESA; reference) crude oil, as well as the effects of weathering on toxicity to embryos of rainbow trout were assessed using increasing concentrations of oil on gravel substrate in continuous‐flow desorption columns. Toxicity was assessed by measurement of the rates of mortality and growth, and the prevalence of blue sac disease, a hallmark sign of oil toxicity. The lower median lethal concentration for HFO compared to MESA indicated that HFO is more toxic. Interestingly, the LC50 values for fresh and weathered for both oils were similar, indicating little change in toxicity when the oil weathers naturally. Repetition of this experiment and analysis of PAH content in each treatment will provide more insight into the environmental and health risks associated with sunken heavy fuel oil.   

Vertical Variability of Primary Production and Chlorophyll a in the Kara Sea in the Middle of Summer: Contribution of Subsurface Maxima to the Water Column Values

Oceanology ◽  
2021 ◽  
Vol 61 (5) ◽  
pp. 645-661
Author(s):  
A. B. Demidov ◽  
V. I. Gagarin ◽  
E. V. Eremeeva ◽  
V. A. Artemiev ◽  
A. A. Polukhin ◽  
...  
Keyword(s):  
Primary Production ◽  
Water Column ◽  
Chlorophyll A ◽  
Kara Sea ◽  
Vertical Variability

Decomposition of Seston in the Hyolimnion

1987 ◽  
Vol 44 (1) ◽  
pp. 146-151 ◽  
Author(s):  
R. J. Cornett ◽  
F. H. Rigler
Keyword(s):  
Oxygen Consumption ◽  
Water Temperature ◽  
Water Column ◽  
Chlorophyll A ◽  
Significant Fraction ◽  
Oxygen Deficit ◽  
Total Oxygen ◽  
Respiration Rates ◽  
Hypolimnetic Oxygen

In 12 lakes a significant fraction of the hypolimnetic oxygen deficit was produced by the respiration of seston in the hypolimnetic water column. Mean summer seston respiration rates ranged between 4 and 80 mg O2∙m−3∙d−1. Rates of seston respiration were proportional to the in situ water temperature and to the concentration of Chlorophyll a. The amount of oxygen consumed in the water column and the fraction of the total oxygen deficit produced by sestonic respiration were correlated with the amount of phosphorus sedimented from the epilimnion. Fifteen to 66% of the total oxygen consumption occurred in the water column of the hypolimnion. Seston respiration was a larger proportion of the total respiration in the hypolimnion of lakes with a thick hypolimnion than in lakes with a shallow hypolimnetic water column.

Evidence that increased nitrogen efflux from wave-influenced marine sediment enhances pelagic phytoplankton production on the inner continental shelf of Western Australia

2010 ◽  
Vol 61 (5) ◽  
pp. 625 ◽  
Author(s):  
Jim Greenwood
Keyword(s):  
Continental Shelf ◽  
Surface Waves ◽  
Water Column ◽  
Chlorophyll A ◽  
Wave Height ◽  
Western Australia ◽  
Regional Scale ◽  
Reaction Rates ◽  
Phytoplankton Production ◽  
Biogeochemical Model

Increased biological and chemical reaction rates within permeable continental-shelf sediment can result from the action of passing surface waves, especially when the seabed is rippled. The effect of this on the exchange of nitrogen between the sediment and water column is the focus of the present paper. The continental shelf of Western Australia is used as an example. A time series of chlorophyll a is compared with surface-wave height revealing seasonal and sub-seasonal correlation between the two variables. At the same time, results from a coupled pelagic–benthic biogeochemical model show that temperature-controlled changes in sedimentary nitrogen efflux cannot account for the observed seasonal changes in chlorophyll a in the overlying water column. It is proposed that enhanced pore-water circulation within the sediment, caused by the action of passing surface waves, results in an increase in the efflux of nitrogen from the sediment during winter, supporting higher pelagic phytoplankton production. The parameterisation of sedimentary nitrogen mineralisation as a function of the square of wave height is suggested for the inclusion of this effect in regional-scale continental shelf models.

Seasonal variations in the Indian Ocean along 110°E. III. Chlorophylls a and c

1969 ◽  
Vol 20 (1) ◽  
pp. 55 ◽  
Author(s):  
GF Humphrey ◽  
JD Kerr
Keyword(s):  
Regression Analysis ◽  
Indian Ocean ◽  
Water Column ◽  
Chlorophyll A ◽  
Seasonal Variations ◽  
The Indian Ocean ◽  
The Mean

The mean concentrations for all samples analysed were 0.17 �g/l for chlorophyll a and 0.22 �g/I. for chlorophyll c; there were 27 mg/m² of a and 35 mg/m² of c in the water column to 150 m. June-August gave the highest values. The model depth at which concentrations were greatest was 75 m. Diagrams of regression surfaces fitted to the results are given. Regression analysis showed that depth, latitude, and season affected the concentration of chlorophylls; latitude and season affected the column amount of chlorophylls.

scholarly journals The Effect of Cold and Warm Anomalies on Phytoplankton Pigment Composition in Waters off the Northern Baja California Peninsula (México): 2007–2016

2020 ◽  
Vol 8 (7) ◽  
pp. 533 ◽  
Author(s):  
Adriana González-Silvera ◽  
Eduardo Santamaría-del-Ángel ◽  
Víctor Camacho-Ibar ◽  
Jorge López-Calderón ◽  
Jonatan Santander-Cruz ◽  
...  
Keyword(s):  
Water Column ◽  
Chlorophyll A ◽  
Community Composition ◽  
High Performance ◽  
Baja California ◽  
Regional Scale ◽  
Baja California Peninsula ◽  
Phytoplankton Pigments ◽  
Entire Water Column ◽  
Satellite Chlorophyll

In this study, we report the response of phytoplankton community composition to cold and warm interannual events affecting the waters off the Baja California Peninsula from 2007 to 2016 based on data obtained from a single marine station (31.75° N/116.96° W). Included variables were satellite chlorophyll a, sea surface temperature (MODIS/Aqua), upwelling intensity, and field data (phytoplankton pigments, inorganic nutrients, light penetration). Phytoplankton pigments were determined by high performance liquid chromatography, and CHEMTAX software was used to determine the relative contributions of the main taxonomic groups to chlorophyll a. Our results confirm the decrease in phytoplankton biomass due to the influence of the recent Pacific Warm Anomaly (2014) and El Niño 2015–2016. However, this decrease was especially marked at the surface. When data from the entire water column was considered, this decrease was not significant, because at the subsurface Chla did not decrease as much. Nevertheless, significant changes in community composition occurred in the entire water column with Cyanobacteria (including Prochlorococcus) and Prymnesiophytes being dominant at the surface, while Chlorophytes and Prasinophytes made a strong contribution at the subsurface. Analysis of the spatial distribution of SST and satellite chlorophyll a made it possible to infer the spatial extension of these anomalies at a regional scale.

scholarly journals A Time Series of Water Column Distributions and Sinking Particle Flux of Pseudo-Nitzschia and Domoic Acid in the Santa Barbara Basin, California

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 480 ◽  
Author(s):  
Blaire Umhau ◽  
Claudia Benitez-Nelson ◽  
Clarissa Anderson ◽  
Kelly McCabe ◽  
Christopher Burrell
Keyword(s):  
Time Series ◽  
Water Column ◽  
Sediment Trap ◽  
Domoic Acid ◽  
Particle Flux ◽  
Sediment Traps ◽  
Benthic Organisms ◽  
Santa Barbara ◽  
Santa Barbara Basin ◽  
Potential Source

Water column bulk Pseudo-nitzschia abundance and the dissolved and particulate domoic acid (DA) concentrations were measured in the Santa Barbara Basin (SBB), California from 2009–2013 and compared to bulk Pseudo-nitzschia cell abundance and DA concentrations and fluxes in sediment traps moored at 147 m and 509 m. Pseudo-nitzschia abundance throughout the study period was spatially and temporally heterogeneous (<200 cells L−1 to 3.8 × 106 cells L−1, avg. 2 × 105 ± 5 × 105 cells L−1) and did not correspond with upwelling conditions or the total DA (tDA) concentration, which was also spatially and temporally diverse (<1.3 ng L−1 to 2.2 × 105 ng L−1, avg. 7.8 × 103 ± 2.2 × 104 ng L−1). We hypothesize that the toxicity is likely driven in part by specific Pseudo-nitzschia species as well as bloom stage. Dissolved (dDA) and particulate (pDA) DA were significantly and positively correlated (p < 0.01) and both comprised major components of the total DA pool (pDA = 57 ± 35%, and dDA = 42 ± 35%) with substantial water column concentrations (>1000 cells L−1 and tDA = 200 ng L−1) measured as deep as 150 m. Our results highlight that dDA should not be ignored when examining bloom toxicity. Although water column abundance and pDA concentrations were poorly correlated with sediment trap Pseudo-nitzschia abundance and fluxes, DA toxicity is likely associated with senescent blooms that rapidly sink to the seafloor, adding another potential source of DA to benthic organisms.

Fate and Transport of Selected Herbicides in an Estuarine Environment

1983 ◽  
Vol 40 (S2) ◽  
pp. s337-s345 ◽  
Author(s):  
J. C. Means ◽  
R. D. Wijayaratne ◽  
W. R. Boynton
Keyword(s):  
Chesapeake Bay ◽  
Water Column ◽  
Fate And Transport ◽  
Water Systems ◽  
Estuarine Environment ◽  
Estuarine Sediments ◽  
Equilibrium Sorption ◽  
Degradation Rates ◽  
Hydrophobic Pollutants ◽  
Ambient Levels

Representative compounds from three classes of herbicides (atrazine, linuron, and treflan) were studied to determine ambient levels in the Chesapeake Bay and its tributaries during portions of 1980. All levels were 1 μg/L or less, and all three herbicides exhibited non-conservative behavior in the estuary. Concentrations of herbicides in runoff from a defined watershed did not exceed 9 μg/L. Degradation rates for all three herbicides in estuarine sediment-water systems were 2–10 times greater than those reported for soils. Equilibrium sorption constants (Koc) of estuarine sediments were similar to soils, but suspended colloids were found to sorb atrazine and linuron 10–30 times more strongly on a per gram of carbon basis, suggesting that refractory hydrophobic pollutants may be transported greater distances in the water column than previously assumed. However, the large degradative capacity of the estuarine community may act to prevent transport of labile organics from the land to the oceans.

scholarly journals Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms

2015 ◽  
Vol 112 (51) ◽  
pp. 15562-15567 ◽  
Author(s):  
Jocelyn Anne Sessa ◽  
Ekaterina Larina ◽  
Katja Knoll ◽  
Matthew Garb ◽  
J. Kirk Cochran ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Water Column ◽  
Oxygen Isotope ◽  
Benthic Foraminifera ◽  
Planktonic Foraminifera ◽  
Type Locality ◽  
Benthic Organisms ◽  
Isotopic Data ◽  
Excellent Opportunity ◽  
Upper Maastrichtian

Ammonites are among the best-known fossils of the Phanerozoic, yet their habitat is poorly understood. Three common ammonite families (Baculitidae, Scaphitidae, and Sphenodiscidae) co-occur with well-preserved planktonic and benthic organisms at the type locality of the upper Maastrichtian Owl Creek Formation, offering an excellent opportunity to constrain their depth habitats through isotopic comparisons among taxa. Based on sedimentary evidence and the micro- and macrofauna at this site, we infer that the 9-m-thick sequence was deposited at a paleodepth of 70–150 m. Taxa present throughout the sequence include a diverse assemblage of ammonites, bivalves, and gastropods, abundant benthic foraminifera, and rare planktonic foraminifera. No stratigraphic trends are observed in the isotopic data of any taxon, and thus all of the data from each taxon are considered as replicates. Oxygen isotope-based temperature estimates from the baculites and scaphites overlap with those of the benthos and are distinct from those of the plankton. In contrast, sphenodiscid temperature estimates span a range that includes estimates of the planktonic foraminifera and of the warmer half of the benthic values. These results suggest baculites and scaphites lived close to the seafloor, whereas sphenodiscids sometimes inhabited the upper water column and/or lived closer to shore. In fact, the rarity and poorer preservation of the sphenodiscids relative to the baculites and scaphites suggests that the sphenodiscid shells may have only reached the Owl Creek locality by drifting seaward after death.

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