scholarly journals Benthic jellyfish dominate water mixing in mangrove ecosystems

2019 ◽  
Author(s):  
David M. Durieux ◽  
Kevin T. Du Clos ◽  
Brad J. Gemmell
Keyword(s):  
Water Column ◽  
Ecosystem Engineer ◽  
Average Rate ◽  
Bell Diameter ◽  
Aquatic Life ◽  
Important Species ◽  
Water Mixing ◽  
Entire Water Column ◽  
Marine Habitats ◽  
Water Column Mixing

AbstractWater mixing is a critical mechanism in marine habitats that governs many important processes, including nutrient transport. Physical mechanisms, such as winds or tides, are primarily responsible for mixing effects in shallow coastal systems, but the sheltered habitats adjacent to mangroves experience very low turbulence and vertical mixing. The significance of biogenic mixing in pelagic habitats has been investigated but remains unclear. In this study we show that the upside-down jellyfish Cassiopea sp. plays a significant role with respect to biogenic contributions to water column mixing within its shallow natural habitat (< 2 m deep). The mixing contribution was determined by means of high-resolution flow velocimetry methods in both the laboratory and in the natural environment. We demonstrate that Cassiopea sp. continuously pumps water from the benthos upward in a vertical jet with flow velocities on the scale of centimeters per second. The volumetric flow rate was calculated to be 212 l h−1 for average sized animals (8.6 cm bell diameter), which translates to turnover of the entire water column every 15 minutes for a median population density (29 animals m−2). In addition, we found Cassiopea sp. are capable of releasing porewater into the water column at an average rate of 2.64 ml h−1 per individual. The release of nutrient-rich benthic porewater combined with strong contributions to water column mixing, suggest a role for Cassiopea sp. as an ecosystem engineer in mangrove habitats.Significance StatementWater mixing is a critical process for aquatic life. Coastal mangrove habitats are vital nurseries for commercially and ecologically important species, but these sheltered habitats experience little water mixing. The upside-down jellyfish, Cassiopea sp., occurs in circumtropical mangrove habitats at high densities. They are epibenthic and pulse nearly continuously, producing a vertical current that transports hundreds of liters of seawater per hour. This results in turnover of the entire water column every 15 minutes for an average population. Additionally, Cassiopea sp. can greatly expedite the transport of nutrient-rich water from sediments into the water column. Thus, Cassiopea sp. represents a previously unrecognized ecosystem engineer that can affect primary productivity, nutrient distribution, and alter new habitats as their range is expanding.

scholarly journals Benthic jellyfish dominate water mixing in mangrove ecosystems

2021 ◽  
Vol 118 (30) ◽  
pp. e2025715118
Author(s):  
David M. Durieux ◽  
Kevin T. Du Clos ◽  
David B. Lewis ◽  
Brad J. Gemmell
Keyword(s):  
Water Column ◽  
Ecosystem Engineer ◽  
Average Rate ◽  
Natural Habitat ◽  
Vertical Mixing ◽  
Volumetric Flow Rate ◽  
Bell Diameter ◽  
Water Mixing ◽  
Marine Habitats ◽  
Water Column Mixing

Water mixing is a critical mechanism in marine habitats that governs many important processes, including nutrient transport. Physical mechanisms, such as winds or tides, are primarily responsible for mixing effects in shallow coastal systems, but the sheltered habitats adjacent to mangroves experience very low turbulence and vertical mixing. The significance of biogenic mixing in pelagic habitats has been investigated but remains unclear. In this study, we show that the upside-down jellyfish Cassiopea sp. plays a significant role with respect to biogenic contributions to water column mixing within its shallow natural habitat (<2 m deep). The mixing contribution was determined by high-resolution flow velocimetry methods in both the laboratory and the natural environment. We demonstrate that Cassiopea sp. continuously pump water from the benthos upward in a vertical jet with flow velocities on the scale of centimeters per second. The volumetric flow rate was calculated to be 212 L⋅h-1 for average-sized animals (8.6 cm bell diameter), which translates to turnover of the entire water column every 15 min for a median population density (29 animals per m2). In addition, we found Cassiopea sp. are capable of releasing porewater into the water column at an average rate of 2.64 mL⋅h−1 per individual. The release of nutrient-rich benthic porewater combined with strong contributions to water column mixing suggests a role for Cassiopea sp. as an ecosystem engineer in mangrove habitats.

Variability of the Horizontal Velocity Structure in the Upper 1600 m of the Water Column on the Equator at 10°W

2006 ◽  
Vol 36 (7) ◽  
pp. 1287-1304 ◽  
Author(s):  
Lucia Bunge ◽  
Christine Provost ◽  
Jonathan M. Lilly ◽  
Marc D’Orgeville ◽  
Annie Kartavtseff ◽  
...  
Keyword(s):  
Water Column ◽  
Velocity Component ◽  
Velocity Structure ◽  
Strong Dependence ◽  
Acoustic Doppler Current Profiler ◽  
Horizontal Velocity ◽  
Vertical Shear ◽  
Equatorial Atlantic ◽  
Entire Water Column ◽  
Current Profiler

Abstract This paper presents initial results from new velocity observations in the eastern part of the equatorial Atlantic Ocean from a moored current-meter array. During the “EQUALANT” program (1999–2000), a mooring array was deployed around the equator near 10°W that recorded one year of measurements at various depths. Horizontal velocities were obtained in the upper 60 m from an upward-looking acoustic Doppler current profiler (ADCP) and at 13 deeper levels from current meters between 745 and 1525 m. To analyze the quasiperiodic variability observed in these records, a wavelet-based technique was used. Quasiperiodic oscillations having periods between 5 and 100 days were separated into four bands: 5–10, 10–20, 20–40, and 40–100 days. The variability shows (i) a strong seasonality (the first half of the series is dominated by larger periods than the second one) and (ii) a strong dependence with depth (some oscillations are present in the entire water column while others are only present at certain depths). For the oscillations that are present in the entire water column the origin of the forcing can be traced to the surface, while for the others the question of their origin remains open. Phase shifts at different depths generate vertical shears in the horizontal velocity component with relatively short vertical scales. This is especially visible in long-duration events (&gt;100 days) of the zonal velocity component. Comparison with a simultaneous lowered acoustic Doppler current profiler (LADCP) section suggests that some of these flows may be identified with equatorial deep jets. A striking feature is a strong vertical shear lasting about 7 months between 745 and 1000 m. These deep current-meter observations would then imply a few months of duration for the jets in this region.

scholarly journals A model for the evolution of the thermal bar system

2012 ◽  
Vol 24 (2) ◽  
pp. 161-177 ◽  
Author(s):  
DUNCAN E. FARROW
Keyword(s):  
Surface Layer ◽  
Water Column ◽  
Thermal Balance ◽  
Spring Warming ◽  
Entire Water Column ◽  
Horizontal Extent ◽  
Thermal Bar ◽  
Stable Surface Layer ◽  
Near Shore ◽  
New Framework

A new framework for modelling the evolution of the thermal bar system in a lake is presented. The model assumes that the thermal bar is located between two regions: the deeper region, where spring warming leads to overturning of the entire water column, and the near shore shallower region, where a stable surface layer is established. In this model the thermal bar moves out slightly more quickly than predicted by a simple thermal balance. Also, the horizontal extent of the thermal bar region increases as it moves out from the shore.

scholarly journals Effects of Water Column Mixing and Stratification on Planktonic Primary Production and Dinitrogen Fixation on a Northern Red Sea Coral Reef

2018 ◽  
Vol 9 ◽  
Author(s):  
Arjen Tilstra ◽  
Nanne van Hoytema ◽  
Ulisse Cardini ◽  
Vanessa N. Bednarz ◽  
Laura Rix ◽  
...  
Keyword(s):  
Coral Reef ◽  
Primary Production ◽  
Water Column ◽  
Red Sea ◽  
Dinitrogen Fixation ◽  
Water Column Mixing ◽  
Northern Red Sea

scholarly journals Fleshy Red Algae Mats Influence Their Environment in the Mediterranean Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Neele Schmidt ◽  
Yusuf C. El-Khaled ◽  
Felix I. Roßbach ◽  
Christian Wild
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Water Temperature ◽  
Mediterranean Sea ◽  
Water Column ◽  
Red Algae ◽  
Water Movement ◽  
Ecosystem Engineer ◽  
Overlying Water ◽  
The Mediterranean

In the Mediterranean Sea, the fleshy red alga Phyllophora crispa forms dense mats of up to 15 cm thickness, mainly located on rocky substrates in water depths below 20 m. Because of the observed density of these mats and some first observations, we hypothesize that P. crispa is a yet undescribed ecosystem engineer that provides a multitude of ecological niches for associated organisms along small-scale environmental gradients. Therefore, we conducted an in-situ pilot study in the Western Mediterranean Sea to assess potential influence of the algae mats on the key environmental factors water movement, temperature and light intensity. We comparatively and simultaneously measured in P. crispa mats, in neighboring Posidonia oceanica seagrass meadows, on neighboring bare rocky substrates without algae mats, and in the directly overlying water column. We used several underwater logging sensors and gypsum clod cards. Findings revealed that P. crispa significantly reduced water movement by 41% compared to the overlying water column, whereas water movement was not affected by P. oceanica meadows and bare rocky substrates. Surprisingly, P. crispa increased the water temperature by 0.3°C relative to the water column, while the water temperature in P. oceanica and on bare rocky substrates was reduced by 0.5°C. Light intensity inside the red algae mats was reduced significantly by 69% compared to the water column. This was similar to measured light reduction of 77% by P. oceanica. These findings highlight the strong influence of the dense red algae mats on some key environmental factors. Their influence is obviously similar or even higher than for the well-known seagrass ecosystem engineer. This may be a factor that facilitates associated biodiversity similarly as described for P. oceanica.

A New Thermal Categorization of Ice-covered Lakes

2021 ◽  
Author(s):  
Bernard Yang ◽  
Mathew Wells ◽  
Bailey McMeans ◽  
Hilary Dugan ◽  
James Rusak ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Water Column ◽  
Wind Stress ◽  
Thermal Regime ◽  
Thermal Stratification ◽  
Trophic Status ◽  
Cold Water ◽  
Entire Water Column ◽  
Lake Type

&lt;p&gt;Lakes are traditionally classified based on their thermal regime and trophic status. While this classification adequately captures many lakes, it is not sufficient to understand seasonally ice-covered lakes, the most common lake type on Earth. We describe the inverse thermal stratification in 19 highly varying lakes and derive a model that predicts the temperature profile as a function of wind stress, area, and depth. The results suggest an additional subdivision of seasonally ice-covered lakes to differentiate under-ice stratification. When ice forms in smaller and deeper lakes, inverse stratification will form with a thin buoyant layer of cold water (near 0&lt;sup&gt;o&lt;/sup&gt;C) below the ice, which remains above a deeper 4&lt;sup&gt;o&lt;/sup&gt;C layer. In contrast, the entire water column can cool to ~0&lt;sup&gt;o&lt;/sup&gt;C in larger and shallower lakes. We suggest these alternative conditions for dimictic lakes be termed &amp;#8220;cryostratified&amp;#8221; and &amp;#8220;cryomictic.&amp;#8221;&lt;/p&gt;

Observations of Turbulent Mixing During a Nonstratification Period in the Yellow Sea

2021 ◽  
Vol 55 (2) ◽  
pp. 185-197
Author(s):  
Yunli Nie ◽  
Xin Luan ◽  
Hua Yang ◽  
Xu Chen ◽  
Dalei Song ◽  
...  
Keyword(s):  
Water Column ◽  
Turbulent Mixing ◽  
Yellow Sea ◽  
Dissipation Rate ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
The Yellow Sea ◽  
Distribution Model ◽  
Entire Water Column ◽  
Diapycnal Diffusivity

Abstract Microstructure profiling measurements collected at the continental shelf of the Yellow Sea (35°38'N, 121°20'E) from December 4 to 5, 2019, were analyzed by focusing on the characteristics of turbulent mixing in the Yellow Sea and its associated influencing factors. The vertical thermohaline structure of the water column was nonstratified during the observation period, resulting in the vertically and temporally consistent distribution of turbulence dissipation and diapycnal diffusivity. The average (in time and space) dissipation rate and diapycnal diffusivity were 2.95 × 10−8 W kg−1 and 1.86 × 10−4 m2 s−1, respectively. In the vertical distribution, intense mixing occurred near the sea surface and within the bottom layers. The temporal variation in dissipation exhibits a diurnal variation that was strongly affected by surface buoyancy flux and wind energy, and a high amount of dissipation was observed at night, with an average dissipation rate of 2.45 × 10−8 W kg−1, which was almost one order of magnitude higher than that in the daytime (3.55 × 10−9 W kg−1). The cumulative distribution functions of the dissipation rate and diapycnal diffusivity across the entire water column during the measurement period could be parameterized by a lognormal distribution model. Further analysis shows that the dissipation rate was positively related to wind speed and rotational barotropic tidal velocity. Compared with the rotating tidal current, wind-driven turbulence was able to penetrate the surface, thereby causing layer mixing throughout the entire water column (R = 0.71), and is a dominant driver of elevated turbulent mixing during wintertime.

scholarly journals Missing links in the study of solute and particle exchange between the sea floor and water column

2020 ◽  
Vol 77 (5) ◽  
pp. 1602-1616 ◽  
Author(s):  
Saskia Rühl ◽  
Charlie Thompson ◽  
Ana M Queirós ◽  
Stephen Widdicombe
Keyword(s):  
Water Column ◽  
Current Knowledge ◽  
Anthropogenic Impacts ◽  
Future Research ◽  
Sea Floor ◽  
Marine Habitats ◽  
Exchange Processes ◽  
Ecosystem Level ◽  
Particle Exchange

Abstract Exchanges of solutes and solids between the sea floor and water column are a vital component of ecosystem functioning in marine habitats around the globe. This review explores particle and solute exchange processes, the different mechanisms through which they interact at the ecosystem level, as well as their interdependencies. Solute and particle exchange processes are highly dependent on the characteristics of the environment within which they takes place. Exchange is driven directly by a number of factors, such as currents, granulometry, nutrient, and matter inputs, as well as living organisms. In turn, the occurrence of exchanges can influence adjacent environments and organisms. Major gaps in the present knowledge include the temporal and spatial variation in many of the processes driving benthic/pelagic exchange processes and the variability in the relative importance of individual processes caused by this variation. Furthermore, the accurate assessment of some anthropogenic impacts is deemed questionable due to a lack of baseline data and long-term effects of anthropogenic actions are often unknown. It is suggested that future research should be transdisciplinary and at ecosystem level wherever possible and that baseline surveys should be implemented and long-term observatories established to fill the current knowledge gaps.

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 Resource Occurrence and Productivity in Existing and Proposed Wind Energy Lease Areas on the Northeast US Shelf

2021 ◽  
Vol 8 ◽  
Author(s):  
Kevin D. Friedland ◽  
Elizabeth T. Methratta ◽  
Andrew B. Gill ◽  
Sarah K. Gaichas ◽  
Tobey H. Curtis ◽  
...  
Keyword(s):  
Habitat Use ◽  
Wind Energy ◽  
Continental Shelf ◽  
Marine Ecosystem ◽  
Atlantic Menhaden ◽  
Offshore Wind ◽  
Offshore Wind Energy ◽  
Important Species ◽  
Marine Habitats ◽  
Northeast Us

States in the Northeast United States have the ambitious goal of producing more than 22 GW of offshore wind energy in the coming decades. The infrastructure associated with offshore wind energy development is expected to modify marine habitats and potentially alter the ecosystem services. Species distribution models were constructed for a group of fish and macroinvertebrate taxa resident in the Northeast US Continental Shelf marine ecosystem. These models were analyzed to provide baseline context for impact assessment of lease areas in the Middle Atlantic Bight designated for renewable wind energy installations. Using random forest machine learning, models based on occurrence and biomass were constructed for 93 species providing seasonal depictions of their habitat distributions. We developed a scoring index to characterize lease area habitat use for each species. Subsequently, groups of species were identified that reflect varying levels of lease area habitat use ranging across high, moderate, low, and no reliance on the lease area habitats. Among the species with high to moderate reliance were black sea bass (Centropristis striata), summer flounder (Paralichthys dentatus), and Atlantic menhaden (Brevoortia tyrannus), which are important fisheries species in the region. Potential for impact was characterized by the number of species with habitat dependencies associated with lease areas and these varied with a number of continuous gradients. Habitats that support high biomass were distributed more to the northeast, while high occupancy habitats appeared to be further from the coast. There was no obvious effect of the size of the lease area on the importance of associated habitats. Model results indicated that physical drivers and lower trophic level indicators might strongly control the habitat distribution of ecologically and commercially important species in the wind lease areas. Therefore, physical and biological oceanography on the continental shelf proximate to wind energy infrastructure development should be monitored for changes in water column structure and the productivity of phytoplankton and zooplankton and the effects of these changes on the trophic system.

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