Vertical Configuration of a Side Scan Sonar for the Monitoring of Posidonia oceanica Meadows

Posidonia oceanica meadows are ecosystem engineers that play several roles in marine environment maintenance. In this sense, monitoring of the spatial distribution and health status of their meadows is key to make decisions about protecting them against their degradation. With the aim of checking the ability of a simple low-cost acoustic method to acquire information about the state of P. oceanica meadows as ecosystem indicators, ground-truthing and acoustic data were acquired over several of these meadows on the Levantine coast of Spain. A 200 kHz side scan sonar in a vertical configuration was used to automatically estimate shoot density, canopy height and cover of the meadows. The wide athwartship angle of the transducer together with its low cost and user friendliness entail the main advantages of this system and configuration: both improved beam path and detection invariance against boat rolling. The results show that canopy height can be measured acoustically. Furthermore, the accumulated intensity of the echoes from P. oceanica in the first 30 centimeters above the bottom is indirectly related to shoot density and cover, showing a relation that should be studied deeply.

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Farmer Preference to High Elevation Rice Technological Packages for Accelerating Technological Dissemination (A case Study in Humbang Hasundutan Regency)

Agro Ekonomi ◽

10.22146/ae.61367 ◽

2021 ◽

Vol 32 (2) ◽

Author(s):

Setia Sari Girsang ◽

Agung B Santosa ◽

Tommy Purba ◽

Deddy R Siagian ◽

Khadijah E Ramija

Keyword(s):

Low Cost ◽

High Elevation ◽

Primary Data ◽

Survey Method ◽

User Friendliness ◽

Level Of Satisfaction ◽

High Level ◽

Level Of Importance

Accelerating the introduction of a new technological package is needed to increase the productivity of high elevation puddled rice in Humbang Hasundutan. The objectives of the study are to find out the perception of the existence of technological packages and farmers' preference for a new technological package. The study used a survey method with primary data gathered using questionnaires. The criteria of locations and respondents were used to obtain relevant respondents and data concerning their knowledge of high elevation puddled rice cultivation. The collected data were processed by using Importance Performance Analysis in order to find out the level of Importance and Satisfaction of the indicators and the valued aspects in the technological package components. The results of the study showed that the socio-economic aspects had to be heeded in organizing the technological package. Indicators having a high level of importance and a low level of satisfaction consisted of production cost, quality of seeds, farmer groups empowerment, technology information institution, capital cost, agricultural tools and machines, pest control, sales price, irrigation canals, and farm roads. On the other hand, introducing new superior seeds, productivity attribute and planting age were important indicators for local farmers as to improve the quality of existing seeds. Farmers group expected that the technological package had a high level of productivity, better access to input, low cost, and good user-friendliness in its application.

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Trait gradients inform predictions of seagrass meadows changes to future warming

Scientific Reports ◽

10.1038/s41598-021-97611-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Arianna Pansini ◽

Gabriella La Manna ◽

Federico Pinna ◽

Patrizia Stipcich ◽

Giulia Ceccherelli

Keyword(s):

Global Warming ◽

Posidonia Oceanica ◽

Shoot Density ◽

Western Mediterranean ◽

Seagrass Meadows ◽

Western Mediterranean Sea ◽

Seagrass Ecosystem ◽

Rhizome Biomass ◽

And Function ◽

Time Substitution

AbstractComparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow shoot density revealed that they work independently, but in the same direction with potential synergism. Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

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Assessment of the ecological structure of Posidonia oceanica (L.) Delile on the northern coast of Lazio, Italy (central Tyrrhenian, Mediterranean)

Italian Botanist ◽

10.3897/italianbotanist.9.46426 ◽

2020 ◽

Vol 9 ◽

pp. 1-19

Author(s):

Valentina Gnisci ◽

Selvaggia Cognetti de Martiis ◽

Alessandro Belmonte ◽

Carla Micheli ◽

Viviana Piermattei ◽

...

Keyword(s):

Anthropogenic Activities ◽

Morphological Variability ◽

Posidonia Oceanica ◽

Shoot Density ◽

Northern Coast ◽

Site Specific ◽

Fragmented Habitat ◽

Ecological Structure ◽

Wide Range

The ecological structure of Posidonia oceanica (L.) Delile meadows was evaluated on the northern coast of Lazio, Italy (central Tyrrhenian, Mediterranean sea). This is an infra-littoral zone with a wide range of anthropogenic activities and high geo-morphological variability, which reflects heterogeneity in shoot density, leaf morphology and biomass in fragmented patches. Genetic variability in populations corresponds to the formation of 3 sub-clusters, in the diverse impacted zones (north, centre and south), being correlated to the geographical distance between sites. AMOVA estimated a high genetic variation showing 43.05% individual differences within populations with a marked differentiation among the populations (56.9%) indicated by Fst value (0.57). These results revealed the role of the genetic structure of seagrasses for determining selectivity of fragmented habitat, in response to natural drivers. They showed that site-specific self-recruitment is related to biodiversity capacity and to the geo-morphological characteristic of the coast.

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Assessment of low-cost, non-electrically powered chlorination devices for gravity-driven membrane water kiosks in eastern Uganda

Waterlines ◽

10.3362/1756-3488.20-00014 ◽

2021 ◽

Vol 40 (2) ◽

pp. 92-106

Author(s):

Lukas Dössegger ◽

Alan Tournefier ◽

Laura Germann ◽

Nicola Gärtner ◽

Timon Huonder ◽

...

Keyword(s):

Supply Chain ◽

Low Income ◽

Membrane Filtration ◽

Low Cost ◽

Evaluation Criteria ◽

Sustainable Supply Chain ◽

User Friendliness ◽

Local Supply ◽

Gravity Driven ◽

Eastern Uganda

Recontamination during transport and storage is a common challenge of water supply in low-income settings, especially if water is collected manually. Chlorination is a strategy to reduce recontamination. We assessed seven low-cost, non-electrically powered chlorination devices in gravity-driven membrane filtration (GDM) kiosks in eastern Uganda: one floater, two in-line dosers, three end-line dosers (tap-attached), and one manual dispenser. The evaluation criteria were dosing consistency, user-friendliness, ease of maintenance, local supply chain, and cost. Achieving an adequate chlorine dosage (∼2 mg/L at the tap and ≥ 0.2 mg/L after 24 h of storage in a container) was challenging. The T-chlorinator was the most promising option for GDM kiosks: it achieved correct dosage (CD, 1.5–2.5 mg/L) with a probability of 90 per cent, was easy to use and maintain, economical, and can be made from locally available materials. The other in-line option, the chlorine-dosing bucket (40 per cent CD) still needs design improvements. The end-line options AkvoTur (67 per cent CD) and AquatabsFlo® (57 per cent CD) are easy to install and operate at the tap, but can be easily damaged in the GDM set-up. The Venturi doser (52 per cent CD) did not perform satisfactorily with flow rates > 6 L/min. The chlorine dispenser (52 per cent CD) was robust and user-friendly, but can only be recommended if users comply with chlorinating the water themselves. Establishing a sustainable supply chain for chlorine products was challenging. Where solid chlorine tablets were locally rarely available, the costs of liquid chlorine options were high (27–162 per cent of the water price).

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Benthic Habitats and the Effects of Fishing

Benthic Habitats and the Effects of Fishing ◽

10.47886/9781888569605.ch35 ◽

2005 ◽

Author(s):

Keyword(s):

Anthropogenic Impacts ◽

Data Sets ◽

Side Scan Sonar ◽

Shallow Subsurface ◽

Natural Processes ◽

Landscape Alteration ◽

Ground Truthing ◽

Processing Techniques ◽

Data Acquisition And Processing ◽

Coastal Louisiana

Coastal Louisiana, like many deltaic land masses, faces continued landscape alteration from natural processes and anthropogenic impacts that affect estuarine habitat. The most promising steps to slow/ mitigate these changes are river diversions that introduce freshwater and sediment to river-flanking environments and to help establish ideal salinities over historic oyster grounds. Critical to the success of these programs is a rapid and accurate means to qualify and quantify changes in oyster habitat. Digital high-resolution acoustic instrumentation linked to modern data acquisition and processing software was used to build baseline of information for evaluating future changes in shallow water bottoms, with special emphasis on oyster habitats. Application of digital side-scan sonar (100 and 500 kHz), a broad-spectrum sub-bottom profiler (4-24 kHz) for rapidly acquiring water column, surficial and shallow subsurface was used to map over 10,000 ha of water bottom. Geo-referenced side scan sonar mosaics were incorporated into a GIS data base. These data sets, “calibrated” with surface sampling, coring, and other “ground truthing” have established that numerically indexed acoustic reflectance intensities correlate closely with surface shell and oyster reef density. With image processing techniques to analyze mosaic reflectance patterns, we estimated the percent and total acreage of several bottom types.

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Seagrass of Vasiliko Bay, Eastern Mediterranean: Lost Cause or Priority Conservation Habitat?

Journal of Marine Science and Engineering ◽

10.3390/jmse8090717 ◽

2020 ◽

Vol 8 (9) ◽

pp. 717

Author(s):

Demetris Kletou ◽

Periklis Kleitou ◽

Ioannis Savva ◽

Martin J. Attrill ◽

Stephanos Charalambous ◽

...

Keyword(s):

Surface Area ◽

Multiple Stressors ◽

Eastern Mediterranean ◽

Ecological Status ◽

Fish Farming ◽

Posidonia Oceanica ◽

Shoot Density ◽

Fish Farms ◽

Leaf Surface Area ◽

Marine Fish Farming

Mediterranean coasts are affected by multiple mounting pressures. In Cyprus, marine fish farming has grown rapidly in the past decade and is concentrated in the west side of Vasiliko Bay. The east coast of this bay has ports, a power station, a desalination unit, a cement factory, a major new oil terminal, and gas storage facilities. The bay is earmarked to create the largest hydrocarbon processing, storing, and transport facility in the region. Here, we assess the status of Posidonia oceanica habitat in an understudied region at the upper thermal, and eastern limit, of this Mediterranean endemic seagrass. An extensive ancient seagrass meadow was revealed, covering about 200 ha across 10 km of coastline, over soft substrata at ca 10–30 m depth, and over hard substrata at ca 0–6 m depth. Seagrass shoot density and leaf surface area decreased, both with increasing depth and with proximity to industrial developments; part of the meadow had been destroyed by dredging to build a jetty. Close to fish farms the seagrass had higher epiphytic biomass as well as lower leaf number, mass, and surface area, all of which indicate adverse effects of eutrophication and increased turbidity. Despite these multiple stressors, most of the meadow was in good ecological status, with some of the highest shoot densities ever reported. Furthermore, iconic species like sea turtles, monk seals, and dolphins were seen during sampling. Posidonia oceanica meadows off Cyprus are among the most valuable in the Mediterranean due to their tolerance of high seawater temperatures. Managers of future coastal developments in the region will need to adhere to European legislation and international conventions designed to secure the socioeconomic benefits of seagrass beds.

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Modeling Posidonia oceanica shoot density and rhizome primary production

Scientific Reports ◽

10.1038/s41598-020-73722-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Elena Catucci ◽

Michele Scardi

Keyword(s):

Random Forest ◽

Primary Production ◽

Large Scale ◽

Posidonia Oceanica ◽

Shoot Density ◽

Large Scale Assessment ◽

Goods And Services ◽

Predictive Variables ◽

Management Perspective ◽

Predicted Values

Abstract Posidonia oceanica meadows rank among the most important and most productive ecosystems in the Mediterranean basin, due to their ecological role and to the goods and services they provide. Estimations of crucial ecological process such as meadows productivity could play a major role in an environmental management perspective and in the assessment of P. oceanica ecosystem services. In this study, a Machine Learning approach, i.e. Random Forest, was aimed at modeling P. oceanica shoot density and rhizome primary production using as predictive variables only environmental factors retrieved from indirect measurements, such as maps. Our predictive models showed a good level of accuracy in modeling both shoot density and rhizome productivity (R2 = 0.761 and R2 = 0.736, respectively). Furthermore, as shoot density is an essential parameter in the estimation of P. oceanica productivity, we proposed a cascaded approach aimed at estimating the latter using predicted values of shoot density rather than observed measurements. In spite of the complexity of the problem, the cascaded Random Forest performed quite well (R2 = 0.637). While direct measurements will always play a fundamental role, our estimates could support large scale assessment of the expected condition of P. oceanica meadows, providing valuable information about the way this crucial ecosystem works.

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Towards ground-truthing of spaceborne estimates of above-ground life biomass and leaf area index in tropical rain forests

Biogeosciences ◽

10.5194/bg-7-2531-2010 ◽

2010 ◽

Vol 7 (8) ◽

pp. 2531-2543 ◽

Cited By ~ 28

Author(s):

P. Köhler ◽

A. Huth

Keyword(s):

Remote Sensing ◽

Rain Forest ◽

Tropical Rain Forest ◽

Forest Growth ◽

Canopy Height ◽

Radar Interferometry ◽

Area Index ◽

Forest Growth Model ◽

Ground Truthing ◽

Remote Sensing Techniques

Abstract. The canopy height h of forests is a key variable which can be obtained using air- or spaceborne remote sensing techniques such as radar interferometry or LIDAR. If new allometric relationships between canopy height and the biomass stored in the vegetation can be established this would offer the possibility for a global monitoring of the above-ground carbon content on land. In the absence of adequate field data we use simulation results of a tropical rain forest growth model to propose what degree of information might be generated from canopy height and thus to enable ground-truthing of potential future satellite observations. We here analyse the correlation between canopy height in a tropical rain forest with other structural characteristics, such as above-ground life biomass (AGB) (and thus carbon content of vegetation) and leaf area index (LAI) and identify how correlation and uncertainty vary for two different spatial scales. The process-based forest growth model FORMIND2.0 was applied to simulate (a) undisturbed forest growth and (b) a wide range of possible disturbance regimes typically for local tree logging conditions for a tropical rain forest site on Borneo (Sabah, Malaysia) in South-East Asia. In both undisturbed and disturbed forests AGB can be expressed as a power-law function of canopy height h (AGB = a · hb) with an r2 ~ 60% if data are analysed in a spatial resolution of 20 m × 20 m (0.04 ha, also called plot size). The correlation coefficient of the regression is becoming significant better in the disturbed forest sites (r2 = 91%) if data are analysed hectare wide. There seems to exist no functional dependency between LAI and canopy height, but there is also a linear correlation (r2 ~ 60%) between AGB and the area fraction of gaps in which the canopy is highly disturbed. A reasonable agreement of our results with observations is obtained from a comparison of the simulations with permanent sampling plot (PSP) data from the same region and with the large-scale forest inventory in Lambir. We conclude that the spaceborne remote sensing techniques such as LIDAR and radar interferometry have the potential to quantify the carbon contained in the vegetation, although this calculation contains due to the heterogeneity of the forest landscape structural uncertainties which restrict future applications to spatial averages of about one hectare in size. The uncertainties in AGB for a given canopy height are here 20–40% (95% confidence level) corresponding to a standard deviation of less than ± 10%. This uncertainty on the 1 ha-scale is much smaller than in the analysis of 0.04 ha-scale data. At this small scale (0.04 ha) AGB can only be calculated out of canopy height with an uncertainty which is at least of the magnitude of the signal itself due to the natural spatial heterogeneity of these forests.

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