Intraspecific variability in the filter mesh size of suspension feeding organisms: the case of invasive Ponto-Caspian corophiids (Crustacea: Amphipoda)

Suspension feeders play pivotal roles in the nutrient cycling of almost all aquatic ecosystems. Since sufficiently large differences in the filter mesh size (FMS) can lead to different food web positions, the inter- and intraspecific variability of this trait might be of community-level importance. The aim of this study was to quantify the range of FMS variation within the three invasive Ponto-Caspian Chelicorophium species based on a large material representing various conditions (1,224 specimens from 40 samples across Central Europe), characterize the components of variation within populations, identify the main factors determining intraspecific differences, and reveal how intraspecific variation affects the FMS overlaps among species. The FMS of the most widespread invader, C. curvispinum, varied within the broadest range (between 2.34–8.28 μm, compared to 2.51–5.97 μm in C. robustum and 1.08–3.23 μm in C. sowinskyi); nevertheless, the contribution of intraspecific plasticity to the invasion success of the species is not evident based on the present study. The within-individual variability of FMS increased with the individual mean of the trait and decreased with body size; however, it showed little differences among samples. The among-individual variation within samples could be partitioned into components related to body size (ontogenetic niche shift/differences among cohorts) and sex (ecological sexual dimorphism) as well as a seemingly random component (individual specialization), varying widely in extent and relative contributions. The FMS of C. curvispinum was significantly larger in the presence of C. sowinskyi than in allopatry, likely reflecting character displacement; however, it did not show further increase when C. robustum was also present. Similar differences could not be observed in C. sowinskyi. The FMS ranges of C. curvispinum and C. robustum never overlapped with that of C. sowinskyi in co-occurrence despite the considerable intraspecific differences among sites, suggesting that their interaction can be seen as a clear case of niche differentiation by food particle size. On the contrary, the strong overlaps observed between C. curvispinum and C. robustum indicate that other factors might play the primary role in their coexistence. The studied species appear to be suitable model organisms for identifying the drivers and mechanisms of FMS variability.

The First Investigation of Microplastics Contamination in Estuarine Located in Puger District, Jember Regency, Indonesia

Microplastics are harmful to the ecosystem and need to solve immediately. Detection of microplastic contamination is the first step to reduce plastics pollution. Estuarine in Puger has a high potential for microplastic pollution related to the multifunction of waters as ports, tourism, fish market, fish processing, and human settlements. However, there are no studies related to microplastic contamination in the area. The objectives of this research were to determine microplastic contamination in the estuarine located in Puger District, Jember Regency, Indonesia. The research results were the first evidence to inform the society and local government about the actual condition of plastic pollution, especially in the aquatic ecosystem. The sampling sites were determined by purposive sampling. Fifty liters of water from each station (with three repetitions) were taken using a 24V water pump and then filtered using stainless steel filter (mesh 5 mm and 0.2 mm). The filtered samples were placed in a sterile bottle sample, stored at 4 ± 20C. Microplastics were counted and categorized according to size, color, and type under a microscope stereo. Microplastic abundance was calculated based on the number of microplastic particles identified per liter of sample water (particle/liter). The result showed that the study area was contaminated by microplastics throughout site sampling, with abundances varying from 0.03 particles/liter to 0.19 particles/liter. The highest microplastic abundance found near the fishery market. The microplastics also vary in size, color, and type. According to characterization, the sources of microplastic contamination come from human-based activities.

Multidimensional niche differentiation might buffer invasion impacts: the case of oligohaline corophiids (Crustacea: Amphipoda) in the Baltic Sea

Multidimensional niche differentiation might increase the stability of coexistence by reducing overall niche overlap which might have implications on the dynamics of biological invasions. The oligohaline Baltic Seais inhabited by three native and one invasive corophiid amphipod species. These filter feeding crustaceans differ in their substrate preferences and salinity optima which could potentially allow their robust coexistence. However, recent theory predicts that competing species must diverge across all non-substitutable resources (e.g., food and space). We have measured the filter mesh size in the four species (i.e., the distance between bristles on the filtering setae), revealing considerable differences among the three natives (Apocorophium lacustre, Corophium multisetosum and C. volutator), whereas the invasive Chelicorophium curvispinum showed strong overlap with A. lacustre. Theory suggests that the four species cannot coexist robustly due to their overlap in food particle size irrespective of differences in their salinity optima and substrate preferences which is in accordance with observations of local extinctions of A. lacustre. Nevertheless, the stability ensuing from the multidimensional niche differentiation might delay competitive exclusion; i.e., the spatial separation by salinity and substrate types might decrease the intensity of competition for food. Our data for co-occurring populations indicate that A. lacustre might be able to decrease its filter mesh size overlap with C. curvispinum by character displacement and its broader salinity tolerance also might help the native species to persist in the region. However, the niche shift of the species might increase its overlap with C. multisetosum.

An experimental justification of industrial water strainer brush cleaner properties

Purpose. Theoretical calculation of the friction resistance of the brush cleaner on the mesh screen of the strainer filter FRU-190-2 for industrial water. Experimental determination of the stiffness of one bristle of a brush cleaner. Experimental study of the resistance to movement of the brush cleaner on the strainer filter mesh screen. The purpose of writing this article is the theoretical calculation of the friction resistance of the brush cleaner on the strainer filter mesh screen of the industrial water strainer filter. Filters with a mesh screen are used in heavy industry for the first stage of water treatment. To design and calculate the properties of the brush cleaner, it is necessary to determine the geometric characteristics of the brush cleaner and the frictional resistance force when moving the brush cleaner on the strainer filter mesh screen. To confirm the results of the theoretical calculation of the frictional resistance of the brush cleaner, performed by methods of strength of materials, it is necessary to conduct an experimental study to determine the stiffness of one bristle of the brush cleaner and the resistance to movement of the brush cleaner bristles on the filter element. The methodology of research consists in theoretical calculation by methods of strength of materialsof friction resistance of a brush on a surface of a mesh filter element of the FRU-190-2 filter for industrial water, development of a technique of carrying out experiment, confirmation of the received analytical results of theoretical calculations by experimental researches. Findings. To determine the drag force of the brush cleaner, analytical solutions have been developed that take into account the influence of physical and geometric parameters of the bristles. Experimental confirmation of theoretical calculations is obtained. Scientific novelty is to establish and prove the cubic dependence of the force on one wire of the brush cleaner on its deflection. Analytical dependences of calculation of effort of movement of a brush on its geometrical parameters are revealed. Practical implications. The developed design technique and the results of calculations and experimental researches provide an possibility at the design stage to justification the geometric and physical properties of the brush cleaner of the strainer filter of industrial water.

Removal of >10 µm Microplastic Particles from Treated Wastewater by a Disc Filter

In this paper, we evaluate the performance of a disc filter that retains microplastic (MP) particles from treated wastewater. A focal plane array-based Fourier transform infrared imaging technique enabled MP quantification and an in-house-built software (MPhunter) facilitated automatic analysis of the obtained infrared spectra. The disc filter retained 89.7% of particles, and 75.6% of their mass. This removal efficiency is comparable to removal rates reported by previous studies. However, the presence of an unexpectedly large number of MP particles whose size substantially exceeded the pore size of the disc filter suggests that particles could either bypass or pass through the filter mesh, somewhat diminishing the performance of the filter. The concentration of MPs in the effluent was 3 MP/L, corresponding to an estimated mass concentration of 0.31 µg/L. The annual MP discharge from the studied WWTP after the disc filter was estimated to be 1.1 kg in 2017. It was hence not a significant contributor to MP emissions in Denmark. Although the operation of the disc filter seems to have been disturbed, it nonetheless achieved a high MP removal rate. Therefore, we conclude that it is a suitable technology to decrease the concentration of discharged MPs in wastewater effluents.

Cytological and bacteriological sampling from filters used for embryo recovery to evaluate the uterine status of donor mares

While testing for uterine bacterial infection is usually performed prior to artificial insemination (AI), samples taken during or after embryo flushing are generally not assessed either in subfertile and old mares or in fertile mares, even though knowledge of the status of the uterine environment in which the embryo is to develop would help to predict the outcome of embryo transfer programmes. The presence of bacteria and inflammatory cells in the liquid retained in the filter after uterine flushing in donors was determined at the moment of embryo recovery. Primarily, a group of mares (n = 8) displaying evident clinical signs of endometritis was selected to evaluate the cytological and bacteriological findings in filters after uterine flushing and in uterine cotton swabs. Two uterine samples (for cytological and bacterial evaluation) were taken with cotton swabs and, subsequently, the uterus was flushed and the efflux was also subjected to bacteriological and cytological analysis. Later, a group of donors (n = 20) was also involved to evaluate the presence of bacteria and polymorphonuclear leukocytes (PMN). After embryo flushing and collection, the efflux retained in the filter was evaluated by cytology and bacteriology. A sterile cotton swab was then scrubbed on the filter mesh, and a bacterial culture was performed. The embryo recovery rate was 30% (n = 6); Escherichia coli was isolated in one efflux sample collected from embryo-productive flushings, while the other five samples were negative by culture. Bacterial growth (not considered as contamination) was observed in a total of three samples, although no inflammatory cells were detected. Bacteria were isolated in endometrial samples collected after embryo flushing in donor mares, although inflammatory cells were never present in the uterus of mares from which embryos were recovered. In the absence of clinical signs, cytological and/or bacteriological samplings are not very useful for estimating the success of embryo recovery in donor mares, but evaluation of the filter and efflux after uterine flushing in donors may provide valuable information regarding uterine status at embryo collection.

“In vitro” evaluation of the bacterivore potential of three Cladoceran species occurring in tropical and subtropical regions

Cladocerans occupy an important position among the bacterial consumers in freshwater food webs, being relatively non-selective filter feeders that can exert a strong impact on microbial populations. We evaluated the bacterivory potential of three cladocerans species of subtropical and tropical occurrence (Ceriodaphnia silvestrii, Daphnia gessneri and Ceriodaphnia cornuta) at different life stages, by scanning electron microscopy (SEM) and by the quantification of their bacterial consumption rates using fluorescently labeled bacteria (FLB). All species showed filter mesh sizes sufficiently narrow to retain bacteria. The largest distance between setules was found in primiparous C. cornuta, and the smallest in neonate D. gessneri. The lowest ingestion (IR) and removal (RR) rates were observed in primiparous C. silvestrii and the highest values were observed in adults of D. gessneri. We conclude that bacteria may be considered an important food supplement, particularly for neonates who presented smaller intersetular distances and higher filtration rates than the other life stages.