Spatio-temporal distribution of suspended particulate matter in the Scheldt estuary (Belgium) and interactions with mesozooplankton

This is a research study on suspended particulate matter (SPM) in estuaries, specifically in the Scheldt estuary in Belgium. The use of image analysis in studying SPM is being explored. The technique as applied by first by Tackx et al.(1995) in quantifying SPM mass and zooplankton body sizes and gut contents was evaluated and improved upon. The conversion of two-dimensional area measurements into biomass (e.g. volumes, weights) was addressed. Furthermore, the technique was used to characterise and differentiate some types of SPM based on their shapes, geometric and fractal dimensions. Semi-automated differentiation between biotic and abiotic particles was demonstrated. Differentiation between detrital particles from different terrestrial plants (e.g. monocotyl vs. dicotyl) was demonstrated to be possible but technical limitations prevent its routine application. Using the image analysis technique plus the classical measurements of dry weight, particulate organic carbon (POC), and chlorophyll a and b concentrations (Chla and Chlb, respectively), an inventarisation of SPM in the Scheldt was done. A longitudinal transect with 16 stations was sampled every month in a period of one year. The transect covers the brackish and freshwater tidal area of the estuary. Results showed a spatio-temporal variation in the SPM in the Scheldt. The temporal variations were due to the seasonal fluctuations in the concentrations of Chla and Chlb. Spatial variations showed a tendency of the brackish stations to be distinct from other stations mainly due to Chla, Chlb and POC concentrations. The image analysis technique was also applied, in parallel with high performance liquid chromatography (HPLC), to quantify zooplankton clearance rates on SPM and phytoplankton, respectively. Based on the gut content approach, both methods were easily comparable and were used to measure clearance rates on phytoplankton (Fph) and SPM (Fspm) by the copepod E. affinis and the cladoceran Daphnia sp. Fph rates were generally higher than Fspm for both taxa, indicating a positive selection for phytoplankton. Finally, the size distribution of SPM in the Scheldt was analysed by the size-spectra approach. Normalised SPM distributions were fitted with linear and polynomial equations, with the latter showing the best fit. Mesozooplankton - prey relationships were tested using the size-based predator - prey relationship model of Sheldon et al. (1977). Problems of fitting the model to biomass data expressed in volumes and in carbon were encountered. However, the model was shown to be applicable to our data, despite the fact that some prerequisites were not met

The geometric features, shape factors and fractal dimensions of suspended particulate matter in the Scheldt Estuary (Belgium)

Water samples from the Scheldt estuary were collected in three fractions: (a) unfiltered water, (b) water filtered through a 50 µm net and (c) water filtered through a 300 µm net. Particles easily recognisable from the majority of the amorphous particles were isolated and their geometric dimensions measured. From the measurements, shapefactors were calculated. Measurement of fractal dimensions was attempted. From the first fraction, the particles isolated and measured were circular and chained diatoms. In the second fraction, zooplankters were easily distinguishable and representatives of the three dominant groups (cladocerans, cyclopoids and calanoids) were measured. In the third fraction, detrital pieces from monocotyledon and dicotyledon plants were recognised, isolated and measured. Fractal dimensions were only measurable in particles from fraction 3. The geometric features, shape factors and fractal dimensions of the particles were tested and proven to be effective ‘fingerprints’ to distinguish these particles from the majority of the unidentifiable amorphous particles in the samples

Genetic Identification of Hyalodaphnia Species and Interspecific Hybrids

Species of the genus Daphnia, in particular the subgenus Hyalodaphnia, represent a taxonomically problematic group due to their phenotypic plasticity, local races and the formation of interspecific hybrids and backcrosses. In this study, we present a genetic approach utilising nuclear DNA to unequivocally identify species and interspecific hybrids. Several nuclear loci (ITS1-ITS2, CA14 and GA13) were amplified by PCR and products were subjected to diagnostic restriction enzymes (restriction fragment length polymorphism; RFLP). The application of this approach to several populations across Europe revealed that the markers are highly consistent and reproducible. In addition, we illustrate with a number of examples how this approach contributed to unravel previously unrecognised taxa, increased the sensitivity of biodiversity studies or contributed to the analysis of resting egg banks. Advantages and disadvantages of this approach compared to existing techniques are discussed and several empirical studies and their results are summarised. [KEYWORDS: Daphnia ; RFLP ; interspecific hybrids]

Image analysis as a tool for measuring particulate matter concentrations and gut content, body size, and clearance rates of estuarine copepods: validation and application

The performance of image analysis in measuring suspended particulate matter concentrations was compared with that of the Coulter counter in different samples including latex spheres, diatoms and natural estuarine waters. The two techniques gave comparable numerical concentrations. Image analysis results also correlated positively with dry weight measurements of estuarine suspended particulate matter samples. The conversion of particle areas measured by image analysis into volumes was addressed by trying to determine the average height of the particles. This was done by plotting volume concentrations from the Coulter counter against area concentrations from image analysis. The resulting linear relationships were found to be significant in homogeneous samples like the spheres and diatoms but not in natural estuarine samples. Further measurements were done on cross-section views of natural particulate matter to estimate the actual height, which was found to be on the average 34% of its average diameter. Also validated is the use of image analysis in measuring body sizes and gut contents of copepods. Results show that the gut resembles a cylinder and its measurement is independent of the animal's orientation at the time of measurement. Body size measurements converted into carbon compared favorably with literature data

Selective feeding of <i>Eurytemora affinis</i> (Copepoda, Calanoida) in temperate estuaries: model and field observations

The copepod Eurytemora affinis generally lives under estuarine conditions, where the suspended particulate matter (SPM) is strongly dominated by non-living particles. This article investigates as to how far E. affinis is capable of feeding selectively on phytoplankton under these extreme circumstances. Selectivity for phytoplankton by E. affinis was studied from samples taken from the Westerschelde (Belgium/The Netherlands). Copepod clearance rates exerted on natural phytoplankton quantified from the gut pigment content were significantly higher than those exerted on total particulate matter, calculated from microscopic image analysis of total gut content and total particulate matter concentration in the water. In addition, gut pigment content data on adult E. affinis measured during spring in three European estuaries (the Gironde (France), the Westerschelde and the Elbe (Germany) were used to study the quantitative response of gut pigment content to varying ratios of phytoplankton to total SPM. A model, expressing maximum gut fluorescence as a function of body weight and gut fluorescence as a product of maximum gut fluorescence with the proportion of phytoplankton to total SPM in the feeding medium, satisfactory fitted the gut fluorescence observations made in the three estuaries. Over the range of phytoplankton-carbon/particulate organic carbon ratios observed in the three estuaries, gut fluorescence decreased with SPM concentration, but maximum gut fluorescence was reached when phytoplankton-carbon was >5% of particulate organic carbon. Limitation of selective feeding apparently only occurred under extremely high SPM loads, such as observed in the Gironde. Maximum gut fluorescence values corresponded exactly to those obtained previously for planktonic copepods in general, affirming the relationship with copepod size

Quality assessment and prediction of Philippine mangoes: A convolutional neural network approach

Philippines is one of the world\u27s leading exporter of mangoes. The country produces many varieties of mangoes, one of which is the \u27Carabao\u27 mango. Several metric tons of mangoes are produced, and these have to be checked for defects before entering the market. With recent advances in technology, it has become efficient and relatively easy to use for these applications. The objective of this paper is to present a non-destructive method to check the quality of mangoes using computer vision (CV) and convolutional neural network (CNN) with a minimal number of samples. An experimental setup was created to simulate a production line. A webcam was used for capturing images of the mangoes, while a mini computer was used for controlling the peripherals. As basis for categorizing the mangoes as either good or bad, the Philippine National Standard (PNS) for mangoes was used. A basic background subtraction algorithm was used to extract the mango\u27s image. With these extracted images, a 2-category network was trained, and the achieved classification accuracy was 97.21%. The goal of having a high accuracy in classifying mangoes was achieved. There are multiple paths to explore in the future, including additional feature extraction methods, different neural networks, and hardware improvements, in order to speed up the sorting process. Moreover, it may be necessary to be able to identify mangoes with only slight defects to be used for other products, such as dried mangoes, to reduce product wastage. © 2019 Insight Society

Beliefs about Promoting Cognitive Health among Filipino Americans Who Care for Persons with Dementia

We examined beliefs about promoting cognitive health among Filipino Americans who care for persons with dementia, their awareness of media information about cognitive health, and their suggestions for communicating such information to other caregivers. We conducted three focus groups (25 participants). The constant comparison method compared themes across focus groups. Caregivers most frequently described cognitive health benefits of social engagement and leisure; next in emphasis were benefits of healthy diets. There was less emphasis on physical activity. Participants had heard from television that avoiding smoking, alcohol, and drugs might promote cognitive health. Ways to inform others about cognitive health included information in Filipino newspapers, and handouts in Filipino languages, distributed in Filipino stores, workplaces, community organizations, and health care facilities. Findings suggest an opportunity to develop public health messages promoting cognitive health that are in-language, published in ethnic-specific media, and that are culturally appropriate for Filipino and other Asian Americans