Anouska Mendzil

Floating Treatment Wetlands (FTWs) have many benefits over Free Water Surface (FWS)wetlands:1. Plant roots assisting in filtering and settling processes for sediment bound P and metals2. Plant roots acting as a large surface area for micro-organism activity in: decomposition, nitrification, and denitrification (removal of BOD and N).3. Mild acidification of water due to release of humic acids; and a C input from senescent vegetation, assisting denitrification.4. They can adjust to varying water levels 5. A higher retention time is possible as they can be made deeper without submergingthe vegetationPercentage removal of nutrients and metals from effluent is around 20-40% higher in FTWs than in conventional FWS ponds. Removal efficiency, particularly of nitrogen, can be further increased with tighter control on the water chemistry (aeration; adding CaCO3; adding acarbon source). 20% coverage of islands is optimal for aerobic basins. 100% cover is optimal for anaerobic basins or aerobic basins where there is artificial aeration. The design the FTW and the control of basin water chemistry is essential for optimising treatment efficiencies.The passive use of activated carbon within layers of floating islands is unlikely to be cost effective

Floating Treatment Wetlands (FTWs) have many benefits over Free Water Surface (FWS)wetlands:1. Plant roots assisting in filtering and settling processes for sediment bound P and metals2. Plant roots acting as a large surface area for micro-organism activity in: decomposition, nitrification, and denitrification (removal of BOD and N).3. Mild acidification of water due to release of humic acids; and a C input from senescent vegetation, assisting denitrification.4. They can adjust to varying water levels 5. A higher retention time is possible as they can be made deeper without submergingthe vegetationPercentage removal of nutrients and metals from effluent is around 20-40% higher in FTWs than in conventional FWS ponds. Removal efficiency, particularly of nitrogen, can be further increased with tighter control on the water chemistry (aeration; adding CaCO3; adding acarbon source). 20% coverage of islands is optimal for aerobic basins. 100% cover is optimal for anaerobic basins or aerobic basins where there is artificial aeration. The design the FTW and the control of basin water chemistry is essential for optimising treatment efficiencies.The passive use of activated carbon within layers of floating islands is unlikely to be cost effective

Aquatic biotelemetry increasingly relies on using acoustic transmitters (‘tags’) that enable passive detection of tagged animals using fixed or mobile receivers. Both tracking methods are resource-limited, restricting the spatial area in which movements of highly mobile animals can be measured using proprietary detection systems. Transmissions from tags are recorded by underwater noise monitoring systems designed for other purposes, such as cetacean monitoring devices, which have been widely deployed in the marine environment; however, no tools currently exist to decode these detections, and thus valuable additional information on animal movements may be missed. Here, we describe simple hybrid methods, with potentially wide application, for obtaining information from otherwise unused data sources. The methods were developed using data from moored, acoustic cetacean detectors (C-PODs) and towed passive receiver arrays, often deployed to monitor the vocalisations of cetaceans, but any...

ABSTRACT The growth and distribution of bivalves in estuaries is generally driven by access to food, hydrodynamic forces and sedimentary conditions that facilitate recruitment and allow persistent settlement. Factors such as site elevation or sediment properties have a significant impact, but there are few studies quantifying the relative importance of different factors in an entire estuary. We carried out an estuary-wide survey of the cockle Cerastoderma edule L. by sampling 343 sites in a small estuary, the Burry Inlet in South Wales, UK. We determined the extent to which site elevation, as an indicator for the duration of feeding, sediment properties and position inside the estuary, explained variation in the size and density of the bivalve. We also analysed the production of faeces and pseudo-faeces per cockle. The population consisted almost entirely of 1-year old cockles, the average size was 14.7 ± 2.7mm and the average density was 56 ± 189 cockles 0.1m-2 (mean ± SD). Altogether 37% of the variation in size was explained by two factors: elevation of site (15%) and amount of clay & silt in sediments (22%). Variation in density appeared to play no significant role in determining size. Density was significantly linked to sediment properties (32%) and position inside the estuary (4%). Sediment biodeposition, the amount of material discharged per cockle, was 0.032 ± 0.017g dry weight, the whole population thereby producing an estimated 387 tonnes of faeces and pseudo-faeces in the entire estuary per day. The study confirmed that access to food is a principal driver of growth, but the relatively small proportion of the variation in size explained by site elevation highlights that other factors play an important role. Sediment characteristics in particular were of importance to variation in size as well as density. It seems plausible that sediment properties were a proxy for factors such as bedload movement and exposure, which are more likely causal factors for distribution patterns. However, the bivalves may also actively favour certain sediment compositions for ease of burrowing and food availability. We suggest that the role of active and passive movement of bivalves within an estuary needs further clarification, which would affect individual growth rates and spatial size distribution patterns. The considerable amount of mucus bound material discharged by cockles suggests that the contribution of prolific bivalves to habitat properties of small estuaries is under-estimated.

In 2014 a benthic infauna survey was carried out in Swansea Bay (Wales, UK), an industrialised embayment with a long history of shipping, industrial and domestic pollution, fishing, dredging and spoil disposal. The purpose of the survey was to generate up-to-date baseline information about the benthic communities in the area, and also to compare the current situation with a similar survey carried out 30 years ago. In 2014 grab samples were retrieved at 101 positions in the wider Swansea Bay area to analyse the infauna benthos as well as sediment grain size distribution. Grab samples were taken with a 0.1m2 Day grab. About 200g of surface sediment were removed for particle size analysis, and the remaining sediment was washed through a sieve with 1mm mesh. The sieve residue was fixed in 4% formaldehyde and stained with Rose Bengal. All benthic fauna was sorted from the samples, identified to species level if possible, and counted. Sediment samples were air dried and passed through a series of sieves from 2mm to 63µm according to the Wentworth-Udden classification scale to determine particle-size distribution.The survey revealed spatially discrete benthic communities including a biodiversity hotspot. Habitat characteristics including sediment properties and the proximity to a sewage outfall explained 17-35% of the variation in the community structure. A group of five common species was found to be particularly persistent over time (Nucula nitidosa, Spisula elliptica, Spiophanes bombyx, Nephtys hombergii, Diastylis rathkei). According to the Infauna Quality Index (IQI) linked to the EU Water Framework Directive (WFD) the average ecological status for 2014 was 'moderate', but eleven samples showing 'poor' and 'bad' status indicated possible negative impacts of dredge spoil disposal. Here the 2014 set of data is made publically available. The comparison of the 2014 data with the 30-year old data was published at http://dx.doi.org/10.3389/fmars.2016.00141.

<p>Coastal dunes are both a vital natural coastal defence and a key ecological habitat; therefore, understanding their evolution is important to inform coastal management. Megatidal environments are the world largest tidal ranges and hence provide a unique endmember of the tidal range continuum. A study site at Crymlyn Burrows, Swansea Bay, UK is monitored here; the area was originally of applied interest due to its identification as a key receptor of the Swansea Bay Tidal Lagoon project. The study site comprises of 2km of dune frontage bounded to the west by hard sea defences and to the east by the River Neath estuary. The intertidal is characterized by a shallow slope and crescentic intertidal bars. Mean spring tidal range at the nearby Mumbles tide gauge is 8.46m; mean wave heights at a wave buoy offshore of the site (depth 9m LAT) are 0.66m and storm wave heights exceed 3m; predominant wind direction is in an alongshore – onshore direction.</p><p>A Sensefly Ebee-RTK drone with a Sony RGB camera has been used to map the dune system and the mid to upper intertidal beach on a monthly – bimonthly frequency since October 2018. Initial post-processing was conducted in the Sensefly Emotion3 software; Pix4D was then used to generate a point cloud from the georeferenced images. RTK-GPS surveyed ground control points distributed over the study area were used to improve the accuracy of the solution. Point clouds were cleaned to remove noise using Cloud Compare, an open source point cloud editor, before being interpolated onto a gridded surface. Comparison of the gridded surface against RTK-GPS surveyed points gave a vertical mean absolute error (MAE) of 0.05m over the beach area. Comparison in the dune area is more complex since the raw point cloud includes the vegetation and hence over-estimates height compared to the bare earth. Based on the raw point cloud, MAE over the dune area was 0.22m; however, when vegetation points were removed using artificial neural network based colour discrimination, the MAE was 0.05m.</p><p>Longshore variation in dune evolution is clearly evident. At the eastern and western ends of the dune system, dune progradation can be observed whereas in the central portion the frontal dune is cliffed and the dune foot position is static or eroding landward. Pressure transducers have been deployed in a longshore array at the neap high tide level to assess variation in wave energy reaching the upper intertidal over the study area.</p><p>This presentation will explore whether this variation in behavior is due to longshore variation in wave energy (erosion potential), variation in sediment availability (accretion potential) or the persistence of antecedent morphology.</p>

As anthropogenic use of the coastal zone diversifies, for example marine energy extraction, the coastal environments of interest to coastal engineers and managers is becoming more varied. Increasingly, the morphodynamics of geomorphologically complex, mixed sediment and geologically constrained beaches are important. Even in areas where erosion and inundation risk is low, understanding of changes to morphodynamics is important to inform ecological studies for environmental impact assessments.

This paper describes a new methodology to map intertidal sediment using a commercially available unmanned aerial system (UAS). A fixed-wing UAS was flown with both thermal and multispectral cameras over three study sites comprising of sandy and muddy areas. Thermal signatures of sediment type were not observable in the recorded data and therefore only the multispectral results were used in the sediment classification. The multispectral camera consisted of a Red–Green–Blue (RGB) camera and four multispectral sensors covering the green, red, red edge and near-infrared bands. Statistically significant correlations (>99%) were noted between the multispectral reflectance and both moisture content and median grain size. The best correlation against median grain size was found with the near-infrared band. Three classification methodologies were tested to split the intertidal area into sand and mud: k-means clustering, artificial neural networks, and the random forest approach. Classific...

There exists limited understanding of the long-term dynamics of the seagrass Zostera noltii and how this is influenced by anthropogenic pressures. Milford Haven is a heavily industrialised estuary and also one of the important sites for Zostera sp. in the UK. In this study we examine all available long-term spatial variability and abundance data of Zostera noltii within Milford Haven using historic datasets. Results show that Z. noltii in all sites have shown meadow expansion when compared to the first obtainable records. Little change in abundance over the past 10-15years for the two sites confirms certain seagrass populations to be robust and thriving. We hypothesise that these populations are showing a level of resilience to the high nutrient levels, disturbance and high turbidity present within the water column of the Haven.