Markus Huettel

Followers

Following

Co-authors

Public Views

Interests

Uploads

Papers by Markus Huettel

Toward a Predictive Understanding of the Benthic Microbial Community Response to Oiling on the Northern Gulf of Mexico Coast

Scenarios and Responses to Future Deep Oil Spills, 2019

Benthic ecosystems often act as a repository for oil contamination that washes ashore or is depos... more Benthic ecosystems often act as a repository for oil contamination that washes ashore or is deposited onto sediments following a major oil spill. Sedimentary microorganisms mediate central ecosystem services on the coast, such as carbon and nutrient cycling, and these services may be adversely impacted by oil perturbation. Thus, during the response to the Deepwater Horizon (DWH) oil discharge in the Gulf of Mexico, considerable effort went into characterizing the response of benthic microbial communities to oil deposition on shorelines of the Northern Gulf where oil came ashore. Oil perturbation elicited a pronounced microbial response in coastal ecosystems, altering the abundance, diversity, and community composition of sedimentary microorganisms. Next-generation gene sequencing and metagenomic approaches, which were not available during previous large oil spills, have revolutionized the field of microbiology, providing new insights into the microbial response after the DWH discharge. This review centers on a case study of the fate of oil contamination in Pensacola Beach sands, which sheds light on the mechanisms of microbially mediated hydrocarbon degradation and the impacts of oiling to ecosystem functions. Analysis of field and laboratory results is discussed along with the technological advances that made these observations possible. Metagenomics enabled the application of ecological theory, thereby building a stronger foundation for the effective prediction of baseline microbial community structure/function and response to oiling. Oil perturbation was shown to resemble a press ecosystem disturbance according to the disturbance-specialization hypothesis. Benthic microbial communities were shown to be resilient, maintained ecosystem functions, and recovered quickly after oil disturbance.

Decomposition of diatoms and nutrient dynamics in permeable North Sea sediments

Continental Shelf Research, 2004

This study addresses the decomposition of diatoms in different permeable North Sea sand beds. Dur... more This study addresses the decomposition of diatoms in different permeable North Sea sand beds. During three cruises in 2001 to the southern German Bight, the regeneration of nutrients was assessed after the experimental deposition of organic matter corresponding to a typical spring diatom bloom in in situ and on-board chamber experiments. The diatom pulse was followed by a high regeneration of nutrients during the first day: 5-10% d À1 of the added nitrogen was converted to NH 4 + and up to 0.67% d À1 of the added biogenic silica was dissolved to Si(OH) 4. These results are used to interpret the response of pore water nutrient concentrations in permeable North Sea sands to seasonal nutrient and phytoplankton dynamics in the water column. The rapid advective solute exchange in these permeable sediments reduces the accumulation of regenerated nutrients, and, thus pore water concentrations of Si(OH) 4 , PO 4 3À and NH 4 + decreased with increasing permeability. All sands were characterized by relatively high NO 3 À concentrations down to 10 cm sediment depth, indicating that the upper sediment layers are oxidized by advective flushing of the bed. Our results demonstrate that biogenic silica and organic matter are rapidly degraded in permeable coastal sands, revealing that these sediments are very active sites of nutrient recycling.

Download

Decomposition of diatoms and nutrient dynamics in permeable North Sea sediments

Continental Shelf Research, 2004

Download

Mucus trap in coral reefs: formation and temporal evolution of particle aggregates caused by coral mucus

Marine ecology. Progress series, Jan 24, 2006

Corals exude large volumes of nutrient-containing mucus when exposed to air during low spring tid... more Corals exude large volumes of nutrient-containing mucus when exposed to air during low spring tides, as a protective mechanism against desiccation and UV radiation. Currents and waves of the incoming flood detach the mucus from the corals, thereby increasing organic carbon and nutrient concentrations in the reef water. During transport into the reef lagoon, a large fraction of the mucus dissolves. Roller-table experiments demonstrated that this dissolved mucus leads to the formation of marine snow. The non-dissolving gel-like fraction of the mucus rapidly accumulates suspended particles from the flood water and forms in temporal sequence mucus strings, flocs, surface films, surface layers and thick mucus floats. In a platform reef in the Great Barrier Reef, Australia, we characterized each of these mucus phases and observed the exponential increase of algal and bacterial cells in the ageing mucus aggregates. Within 3 hours, the dry weight of the aggregates increased 35-fold, chlorophyll a 192-fold, bacteria cell density 546-fold, C 26-fold, and N 79-fold. After waves destroy the buoyant mucus floats, the mucus aggregates release enclosed gas bubbles and quickly sink to the lagoon sediments, where they are consumed by the benthic community. This releases aggregate-bound nutrients, which fuel benthic and planktonic production in the lagoon. During ebb tide, corals filter the lagoon water and close the recycling loop. We conclude that coral mucus enhances the filtration capacity of coral reefs and fuels reef benthos, thereby increasing the import of oceanic particles and enhancing recycling in the reef ecosystem.

Download

Rapid recycling of coral mass-spawning products in permeable reef sediments

Marine Ecology Progress Series, 2004

During the annual synchronous release of gametes by corals, a large amount of energyrich organic ... more During the annual synchronous release of gametes by corals, a large amount of energyrich organic material is released to the reef environment. In November 2001, we studied a minor spawning event at Heron Island in the Great Barrier Reef (GBR), Australia. Laboratory experiments showed that egg release by the staghorn coral Acropora millepora amounted to 19 ± 15 g dry mass (mean ± SE, n = 8) per m 2 coral surface. Carbon content reached 60.1 ± 4.0% and nitrogen content 3.6 ± 0.4% of the egg dry mass. During this minor spawning period, Acropora corals from the reef crest released 7 g C and 0.4 g N as eggs m-2 reef. In situ experiments (n = 11) using stirred benthic chamber measurements revealed that the sedimentary O 2 consumption (SOC) of the lagoon sediments increased sharply immediately after the coral spawning. Extreme SOC rates of 230 mmol O 2 m-2 d-1 were reached 2 d after the event, exceeding the pre-spawning rate by a factor of 2.5. This maximum was followed by a steep decrease in SOC rates that gradually levelled off and reached prespawning values 11 d after the event. The immediate and strong response of SOC shows that the coral spawning event provides a strong food impulse to the benthic food chain. Our results demonstrate high decomposition efficiency of permeable carbonate reef sands and underline the role of these sediments as a biocatalytical recycling system in the oligotrophic reef environment.

Download

The influence of topography on the functional exchange surface of marine soft sediments, assessed from sediment topography measured in situ

Limnology and Oceanography, 2005

We investigated the influence of small-scale topography on the exchange surface between sediment ... more We investigated the influence of small-scale topography on the exchange surface between sediment and water in two coastal marine sediments. One site was a sandy silt at Giglio Island, Italy. The sediment was rich in organic material, had a very active fauna, and a rich surface topography. The second site was an estuarine mud in Aarhus Bay, Denmark, which had

Characterization of the Effects of Microbial Processing in Gulf of Mexico Coastal Sands on the Composition of Dissolved Organic Matter Using Ultrahigh Resolution Mass Spectrometry

Permeable coastal sands along the Gulf coast of Florida filter large volumes of water containing ... more Permeable coastal sands along the Gulf coast of Florida filter large volumes of water containing terrestrially derived humic materials, but there is very limited data on the biogeochemical and microbial processes affecting Dissolved Organic Matter (DOM) turnover during filtration. DOM undergoes changes as it moves from fresh water sources through estuaries and into the coastal zone. We have used ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) to define the exact molecular changes associated with DOM filtration through these sands. High field (9.4 Tesla) FT-ICR MS can resolve greater than 10,000 peaks and provide elemental composition (CcHhOoNnSs) for individual compounds found in complex DOM mixtures. Microbially dense sand cores were obtained from off the Gulf coast side of St. George Island located at Apalachicola Bay near the mouth of the Apalachicola River in Northern Florida. Humic-rich river water and water spiked with "fresh&q...

Eddy correlation measurements of oxygen fluxes in permeable sediments exposed to varying current flow and light

Limnology and Oceanography

Based on noninvasive eddy correlation measurements at a marine and a freshwater site, this study ... more Based on noninvasive eddy correlation measurements at a marine and a freshwater site, this study documents the control that current flow and light have on sediment-water oxygen fluxes in permeable sediments. The marine sediment was exposed to tidal-driven current and light, and the oxygen flux varied from night to day between -29 and 78 mmol m(-2) d(-1). A fitting model, assuming a linear increase in oxygen respiration with current flow, and a photosynthesis-irradiance curve for light-controlled production reproduced measured fluxes well (R-2 = 0.992) and revealed a 4-fold increase in oxygen uptake when current velocity increased from similar to 0 to 20 cm s(-1). Application of the model to a week-long measured record of current velocity and light showed that net ecosystem metabolism varied substantially among days, between -27 and 31 mmol m(-2) d(-1), due to variations in light and current flow. This variation is likely typical of many shallow-water systems and highlights the need ...

Download

Importance of phytodetritus and microphytobenthos for heterotrophs in a shallow subtidal sandy sediment

Marine Ecology Progress Series

The relative importance of allochthonous phytodetritus deposition and autochthonous microphytoben... more The relative importance of allochthonous phytodetritus deposition and autochthonous microphytobenthos (MPB) production for benthic consumers in an organic carbon (Corg)-poor sandy sediment was assessed using a 13C-stable isotope natural abundance study combined with a dual 13C-tracer addition approach. In a first experiment (Expt 1), a set of sediment cores received a pulse of 13C-labelled phytodetritus and the fate of that organic matter was followed in the benthic food web (bacteria, meiofauna and macrofauna) over a period of 72 h. In a second experiment (Expt 2), the MPB present in a set of sediment cores was labelled with 13C-bicarbonate and the fate of labelled MPB was followed the same way over a period of 96 h. Natural 13C abundances of sources and consumers revealed that the benthic food web likely relied primarily on MPB. In particular, diatoms contributed at least 40% to the diet of 12 out of the 16 taxonomic groups identified. The dual approach revealed the complexity of ...

Download

Carbon and nitrogen flows through the benthic food web of a photic subtidal sandy sediment

Marine Ecology Progress Series

Carbon and nitrogen flows within the food web of a subtidal sandy sediment were studied using sta... more Carbon and nitrogen flows within the food web of a subtidal sandy sediment were studied using stable isotope natural abundances and tracer addition. Natural abundances of 13C and 15N stable isotopes of the consumers and their potential benthic and pelagic resources were measured. δ13C data revealed that consumers did not feed on the bulk microphytobenthos (MPB) but rather were selective in their food uptake, preferring either benthic diatoms (–16‰), or benthic cyanobacteria (–20‰). MPB was labelled through a pulse-chase experiment with 13C-bicarbonate and 15N-nitrate. The fate of MPB was followed in the different heterotrophic compartments. Transfer of 13C and 15N to consumers was fast, although only a small fraction of total label was transferred to the heterotrophic compartments within the 4 d of the experiment. Heterotrophic bacteria were responsible for most of the total heterotrophic incorporation of 13C. Within the metazoan community, the incorporation of 13C by the meiofauna ...

Download

Buchbesprechungen

Helgoläander Meeresuntersuchungen

Effects of throughflow and internal heat generation on convective instabilities in an anisotropic porous layer

Journal of Porous Media

Convective instabilities caused by a nonunlform temperature gradient due to vertical through/low ... more Convective instabilities caused by a nonunlform temperature gradient due to vertical through/low and internal heat generation were investigated in an anisotropic porous layer. The boundaries are taken to be either impermeable or porous and are perfect conductors of heat. The Forchheimer-extended Darcy model is used to describe the/low in the porous medium. The resulting eigenvalue problem is solved numerically by the Galerkin method with a modified external Rayleigh number as the eigenvalue. Both anisotropic parameters (i.e., effective thermal diffusivity, h, and permeability, x) appear through their ratio h/x only. We found that an increase in h/x increases the stability of the system. Furthermore, we observed that in the absence of internal heat generation, throughflow stabilizes when the boundaries are symmetric and destabilizes when they are asymmetric. However, if an internal heat source exists, throughflow destabilizes the system irrespective of the boundary types considered. ...

Measuring oxygen uptake by marine sediments using a new eddy correlation technique

Water column oxygen dynamics within the coastal gradient in the northeastern Gulf of Mexico inner shelf

Continental Shelf Research, 2015

ABSTRACT This study quantified the coastal gradients of salinity, temperature, nutrients, chlorop... more ABSTRACT This study quantified the coastal gradients of salinity, temperature, nutrients, chlorophyll and oxygen along a transect from 5 to 18 m depth in the northeastern Gulf of Mexico (NEGOM) through measurements of water column profiles over 4.5-years and recordings of probes mounted at 0.5 m above the seafloor over 2-years. The main goal was to determine the influences of the coastal gradients on water column oxygen concentration distributions. Apalachicola River discharge affected the study region as reflected in low-salinity surface layers. Decreasing rates of oxygen production and consumption from the shallowest station to the deepest station were attributed to measured coastal gradients of nutrients and the decreasing influence of seafloor processes with increasing distance from shore. Water column photosynthetic oxygen production at a realistic irradiance of 200 μE m−2 s−1 ranged from 0.5 to 4.5 mmol O2 m−3 h−1, and dark consumption rates from 0.2 to 2.6 mmol O2 m−3 h−1. Based on July irradiance profiles and associated production and consumption rates, the water column in July 2009 produced 0.9 (1 SD=0.2) g C m−2 d−1 with rates remaining relatively constant over the length of this coastal transect. Benthic boundary layer production reaching 26% to 43% of the surface layer production underlines the role of the benthic boundary layer for production in the inner shelf. Oxygen in the benthic boundary layer never decreased below 73% air saturation, and hypoxic zones, as reported from shelf areas west of the study region, did not occur. Oxygen production exceeded consumption suggesting a net autotrophic system.

Technical Note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

Biogeosciences Discussions, 2015

ABSTRACT Extracting benthic oxygen fluxes from eddy covariance time series measured in the presen... more ABSTRACT Extracting benthic oxygen fluxes from eddy covariance time series measured in the presence of surface gravity waves requires careful consideration of the temporal alignment of the vertical velocity and the oxygen concentration. Using a model based on linear wave theory and measured eddy covariance data, we show that substantial erroneous fluxes can arise if these two variables are not aligned correctly in time. We refer to this error in flux as the time lag bias. In one example, produced with the wave model, we found that an offset of 0.25 s between the oxygen and the velocity data produced a two-fold overestimation of the flux. In another example, relying on nighttime data measured over a seagrass meadow, a similar offset reversed the flux from an uptake of −50 mmol m−2 d−1 to a release of 40 mmol m−2 d−1. The bias is most acute for data measured at shallow-water sites with short-period waves and low current velocities. At moderate or higher current velocities (&gt; 5–10 cm s−1), the bias usually is insignificant. The widely used traditional time shift correction for data measured in unidirectional flows, where the maximum numerical flux is sought, should not be applied in the presence of waves because it tends to maximize the time lag bias. Based on wave model predictions and measured data, we propose a new time lag correction that minimizes the time lag bias. The correction requires that time series of both vertical velocity and oxygen concentration contain a clear periodic wave signal. Because wave motions are often evident in eddy covariance data measured at shallow-water sites, we encourage more work on identifying new time lag corrections. On that premise, we make all raw data used in this study available to interested users.

Flow-induced uptake of particulate matter in permeable sediments

by Markus Huettel and Wiebke Ziebis

Limnology and Oceanography, 1996

We demonstrate the fast transfer of suspended particles from the boundary layer into the upper st... more We demonstrate the fast transfer of suspended particles from the boundary layer into the upper strata (z < 4 cm) of permeable sediments with topography-related interfacial water flows. The transport is driven by pressure gradients (A P I 3 Pa) generated when bottom flows (u I 10 cm s-l) are deflected by small surface structures (z < 3 cm) of hydrodynamical or biological origin. Acrylic pigment grains of 1 -and 1 O-pm diameter traced the intrusion of particulate matter into sandy sediment (k > 2 x 10-l l m2) incubated in a laboratory flume. Increased pressure up-and downstream of small mounds (z = 2.5 cm) drove water 5.5 cm into the core, carrying suspended particles (1 pm) to 2.2-cm sediment depth within 10 h. Simultaneously, decreased pressure at the downstream slope of the protrusions drew pore fluid from deeper layers (z 5 10 cm) to the surface. In the sediment, friction reduced the velocity of the particulate tracers, resulting in size fractionation and layers of increased particle concentration. Ripple topography (0.8-2.8 cm high) enhanced interfacial particle (1 pm) flux by a factor 2 .3 when compared to a level control core. The pathways of the particle and solute tracers below a sediment ripple are explained with a source-sink model that describes the pore flow velocity field. Our results suggest that bedform-induced interfacial flows are important for the uptake of particulate organic matter into permeable shelf sediments.

Download

Vertical Migration in the Sediment-Dwelling Sulfur Bacteria Thioploca spp. in Overcoming Diffusion Limitations

Applied and environmental microbiology, 1996

In order to investigate the environmental requirements of the filamentous sulfur bacteria Thioplo... more In order to investigate the environmental requirements of the filamentous sulfur bacteria Thioploca spp., we tested the chemotactic responses of these sedimentary microorganisms to changes in oxygen, nitrate, and sulfide concentrations. A sediment core with a Thioploca mat, retrieved from the oxygen-minimum zone on the Chilean shelf, was incubated in a recirculating flume. The addition of 25 (mu)mol of nitrate per liter to the seawater flow induced the ascent of the Thioploca trichomes (length, up to 70 mm) in their mostly vertically oriented gelatinous sheaths. The upper ends of the filaments penetrated the sediment surface and protruded 1 to 3 mm into the flowing water before they bent downstream. By penetrating the diffusive boundary layer, Thioploca spp. facilitate efficient nitrate uptake in exposed trichome sections that are up to 30 mm long. The cumulative length of exposed filaments per square centimeter of sediment surface was up to 92 cm, with a total exposed trichome surf...

Download

Benthic exchange and biogeochemical cycling in permeable sediments

Annual review of marine science, 2014

The sandy sediments that blanket the inner shelf are situated in a zone where nutrient input from... more The sandy sediments that blanket the inner shelf are situated in a zone where nutrient input from land and strong mixing produce maximum primary production and tight coupling between water column and sedimentary processes. The high permeability of the shelf sands renders them susceptible to pressure gradients generated by hydrodynamic and biological forces that modulate spatial and temporal patterns of water circulation through these sediments. The resulting dynamic three-dimensional patterns of particle and solute distribution generate a broad spectrum of biogeochemical reaction zones that facilitate effective decomposition of the pelagic and benthic primary production products. The intricate coupling between the water column and sediment makes it challenging to quantify the production and decomposition processes and the resultant fluxes in permeable shelf sands. Recent technical developments have led to insights into the high biogeochemical and biological activity of these permeab...

GEOC 11-Molecular and photochemical characterization of terrestrially-derived DOM in estuarine environments by ultrahigh resolution mass spectrometry and 3-D excitation/emission matrix spectroscopy

Microbial community successional patterns in beach sands impacted by the Deepwater Horizon oil spill

by Markus Huettel and Joel Kostka

The ISME Journal, 2015

Although petroleum hydrocarbons discharged from the Deepwater Horizon (DWH) blowout were shown to... more Although petroleum hydrocarbons discharged from the Deepwater Horizon (DWH) blowout were shown to have a pronounced impact on indigenous microbial communities in the Gulf of Mexico, effects on nearshore or coastal ecosystems remain understudied. This study investigated the successional patterns of functional and taxonomic diversity for over 1 year after the DWH oil was deposited on Pensacola Beach sands (FL, USA), using metagenomic and 16S rRNA gene amplicon techniques. Gamma- and Alphaproteobacteria were enriched in oiled sediments, in corroboration of previous studies. In contrast to previous studies, we observed an increase in the functional diversity of the community in response to oil contamination and a functional transition from generalist populations within 4 months after oil came ashore to specialists a year later, when oil was undetectable. At the latter time point, a typical beach community had reestablished that showed little to no evidence of oil hydrocarbon degradation potential, was enriched in archaeal taxa known to be sensitive to xenobiotics, but differed significantly from the community before the oil spill. Further, a clear succession pattern was observed, where early responders to oil contamination, likely degrading aliphatic hydrocarbons, were replaced after 3 months by populations capable of aromatic hydrocarbon decomposition. Collectively, our results advance the understanding of how natural benthic microbial communities respond to crude oil perturbation, supporting the specialization-disturbance hypothesis; that is, the expectation that disturbance favors generalists, while providing (microbial) indicator species and genes for the chemical evolution of oil hydrocarbons during degradation and weathering.The ISME Journal advance online publication, 17 February 2015; doi:10.1038/ismej.2015.5.

Markus Huettel

Uploads

Papers by Markus Huettel

Log In