155 research outputs found
Seasonal variability of turbidity, salinity, temperature and suspended chlorophyll in a strongly tidal sub-estuary: The Lynher Marine Conservation Zone
The Lynher Estuary in Southwest England is a small, strongly tidal sub-estuary of the Tamar Estuary. It is a Site of Special Scientific Interest (SSSI), a Marine Conservation Zone (MCZ), a part of the Plymouth Sound and Estuaries Special Area of Conservation (SAC) and a Special Protection Area (SPA). Management of the Lynher SSSI and MCZ stipulates that good water quality and sediment quality should be maintained; as such, a good understanding of its responses to influences such as climate change and changes in agricultural practices within its catchment area is required. Observations of salinity, temperature, suspended particulate matter (SPM) concentrations, estuarine turbidity maximum (ETM) behaviour, and chlorophyll-a are presented for the Lynher over a 1-y period. The dataset provides important baseline information with which to identify future changes and guide management of the SSSI and MCZ as well as adding to our knowledge of estuarine systems. Salt intrusion is largely controlled by tides and runoff. A persistent ETM occurs that is closely associated with the freshwater-saltwater interface at high water (HW) and with a minimum in dissolved oxygen concentrations. HW depth-averaged ETM magnitudes are relatively low, less than 60âŻmgâŻlâ1 and typically 30âŻmgâŻlâ1 over the observation period. Larger tides and stronger flood-tide wind speeds lead to a stronger ETM. Tidal river HW SPM concentrations are intrinsically small (8âŻÂ±âŻ8âŻmgâŻlâ1 during the observation period). Surface chlorophyll-a concentrations are low during winter (when they often peak near the ETM) and are much higher during spring and summer
Fortnightly changes in water transport direction across the mouth of a narrow estuary
This research investigates the dynamics of the axial
tidal flow and residual circulation at the lower Guadiana
Estuary, south Portugal, a narrow mesotidal estuary with low
freshwater inputs. Current data were collected near the deepest
part of the channel for 21 months and across the channel
during two (spring and neap) tidal cycles. Results indicate
that at the deep channel, depth-averaged currents are stronger
and longer during the ebb at spring and during the flood at
neap, resulting in opposite water transport directions at a
fortnightly time scale. The net water transport across the entire
channel is up-estuary at spring and down-estuary at neap, i.e.,
opposite to the one at the deep channel. At spring tide, when
the estuary is considered to be well mixed, the observed
pattern of circulation (outflow in the deep channel, inflow
over the shoals) results from the combination of the Stokes
transport and compensating return flow, which varies laterally
with the bathymetry. At neap tide (in particular for those of
lowest amplitude each month), inflows at the deep channel are
consistently associated with the development of gravitational
circulation. Comparisons with previous studies suggest that
the baroclinic pressure gradient (rather than internal tidal
asymmetries) is the main driver of the residual water transport.
Our observations also indicate that the flushing out of the
water accumulated up-estuary (at spring) may also produce
strong unidirectional barotropic outflow across the entire
channel around neap tide.info:eu-repo/semantics/publishedVersio
The hyperturbid state of the water column in estuaries and rivers: the importance of hindered settling
Abundance and diversity of tidal marsh plants along the salinity gradient of the San Francisco Estuary: implications for global change ecology
Perspectives and Integration in SOLAS Science
Why a chapter on Perspectives and Integration in SOLAS Science in this book? SOLAS science by its nature deals with interactions that occur: across a wide spectrum of time and space scales, involve gases and particles, between the ocean and the atmosphere, across many disciplines including chemistry, biology, optics, physics, mathematics, computing, socio-economics and consequently interactions between many different scientists and across scientific generations. This chapter provides a guide through the remarkable diversity of cross-cutting approaches and tools in the gigantic puzzle of the SOLAS realm.
Here we overview the existing prime components of atmospheric and oceanic observing systems, with the acquisition of oceanâatmosphere observables either from in situ or from satellites, the rich hierarchy of models to test our knowledge of Earth System functioning, and the tremendous efforts accomplished over the last decade within the COST Action 735 and SOLAS Integration project frameworks to understand, as best we can, the current physical and biogeochemical state of the atmosphere and ocean commons. A few SOLAS integrative studies illustrate the full meaning of interactions, paving the way for even tighter connections between thematic fields. Ultimately, SOLAS research will also develop with an enhanced consideration of societal demand while preserving fundamental research coherency.
The exchange of energy, gases and particles across the air-sea interface is controlled by a variety of biological, chemical and physical processes that operate across broad spatial and temporal scales. These processes influence the composition, biogeochemical and chemical properties of both the oceanic and atmospheric boundary layers and ultimately shape the Earth system response to climate and environmental change, as detailed in the previous four chapters. In this cross-cutting chapter we present some of the SOLAS achievements over the last decade in terms of integration, upscaling observational information from process-oriented studies and expeditionary research with key tools such as remote sensing and modelling.
Here we do not pretend to encompass the entire legacy of SOLAS efforts but rather offer a selective view of some of the major integrative SOLAS studies that combined available pieces of the immense jigsaw puzzle. These include, for instance, COST efforts to build up global climatologies of SOLAS relevant parameters such as dimethyl sulphide, interconnection between volcanic ash and ecosystem response in the eastern subarctic North Pacific, optimal strategy to derive basin-scale CO2 uptake with good precision, or significant reduction of the uncertainties in sea-salt aerosol source functions. Predicting the future trajectory of Earthâs climate and habitability is the main task ahead. Some possible routes for the SOLAS scientific community to reach this overarching goal conclude the chapter
Statistical Models of Temperature in the SacramentoâSan Joaquin Delta Under Climate-Change Scenarios and Ecological Implications
Quantifying the historic contribution of Olympia oysters to filtration in Pacific Coast (USA) estuaries and the implications for restoration objectives
An approach for the identification of exemplar sites for scaling up targeted field observations of benthic biogeochemistry in heterogeneous environments
Continental shelf sediments are globally important for biogeochemical activity. Quantification of shelf-scale stocks and fluxes of carbon and nutrients requires the extrapolation of observations made at limited points in space and time. The procedure for selecting exemplar sites to form the basis of this up-scaling is discussed in relation to a UK-funded research programme investigating biogeochemistry in shelf seas. A three-step selection process is proposed in which (1) a target area representative of UK shelf sediment heterogeneity is selected, (2) the target area is assessed for spatial heterogeneity in sediment and habitat type, bed and water column structure and hydrodynamic forcing, and (3) study sites are selected within this target area encompassing the range of spatial heterogeneity required to address key scientific questions regarding shelf scale biogeochemistry, and minimise confounding variables. This led to the selection of four sites within the Celtic Sea that are significantly different in terms of their sediment, bed structure, and macrofaunal, meiofaunal and microbial community structures and diversity, but have minimal variations in water depth, tidal and wave magnitudes and directions, temperature and salinity. They form the basis of a research cruise programme of observation, sampling and experimentation encompassing the spring bloom cycle. Typical variation in key biogeochemical, sediment, biological and hydrodynamic parameters over a pre to post bloom period are presented, with a discussion of anthropogenic influences in the region. This methodology ensures the best likelihood of site-specific work being useful for up-scaling activities, increasing our understanding of benthic biogeochemistry at the UK-shelf scale
View from the chair: Lest We Forget. In: ECSA Bulletin (ed. J-P. A. Ducrotoy) ISSN: 1352-4615 No. 58 Winter 2011 32pp. www.ecsa-news.org. 3-4.
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