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La última valoración sobre la extensión, estado y cobertura viva (%) de las formaciones de Acropora palmata (29) y A. cervicornis (12) en el Parque Nacional Natural Tayrona fue realizada en 2001 y publicada en 2004. Estas mismas formaciones, incluyendo una adicional en isla Aguja, fueron evaluadas de nuevo entre 2016 y 2018 teniendo en cuenta las mismas variables, y adicionalmente el registro de condición de las colonias. Para A. palmata se encontraron 24 formaciones con una reducción en área de 28,9 %. La cobertura promedio aumentó cerca de 2,0 %, y se observó una amplia distribución de frecuencia de tallas y una proporción importante de colonias con territorios de peces damisela (Stegastes). El área de las formaciones de A. cervicornis se redujo 99,3 % y solo se encontró una formación en Nenguange, aunque se registran dos nuevas y pequeñas en Cinto y otra en Chengue. La cobertura promedio fue de 8,0 %, en su mayoría constituida por colonias de talla pequeña y principalmente afectadas por blanqueamiento, macroalgas, enfermedades y depredadores. Claramente el estatus de las dos especies es diferente por lo que requieren esfuerzos diferentes para su manejo y conservación. Las formaciones de A. palmata han persistido, pero es necesario realizar estudios continuos que permitan detectar cambios temporales, con evaluaciones de aspectos ecológicos como las afectaciones por los peces damisela. El estado de A. cerviconis es crítico, por lo que demanda acciones urgentes de restauración y otras medidas de manejo para mitigar la tendencia a su desaparición en el área.

Much of the contribution of bivalves to paleoecology is based on the fraction preserved whole. The use of fragments has been limited by the inability to reconstruct the whole shell. For this study, shells of selected species were broken, metrics obtained for shell reconstruction, and a stepwise model developed and tested to evaluate the potential of reconstructing whole shells from fragments. The model is based on the facts that shell thickness is well correlated with shell length, width, and weight, that fragments can be assigned to shell areas, and that each shell area can be matched to a potential donor shell by combinations of length, width, and weight. Simulations using the model show that shell reconstructions are feasible and that the size frequency can be reconstructed more accurately than the number of shells. If all fragments are preserved, shell number tends to be modestly overestimated. Assuming fragment loss, the shell number estimated will be a conservative estimate of original abundance. Reconstructed size frequencies did not differ significantly from the original size frequencies of the whole shells even if 40% of the fragments were not preserved. Biovolume, consequently, may also be estimable. Standardly, bivalve fragments are enumerated by counting intact umbos. If all fragments are preserved, this approach is preferable, as shell model reconstructions overestimate abundance under that circumstance. However, the expectation that fragments with intact umbos are uniquely well preserved is unrealistic and if fragment loss has occurred, relying on all fragments may provide an improved estimate of the original abundance and, in addition, an estimate of the size frequency and the latter proves to be robust even with 40% of the fragments lost.

Accurate characterization of oocyte development is essential to understanding foundational aspects of reproductive biology and successful management of Pacific halibut (Hippoglossus stenolepis). Here this study provides complete histological descriptions for eight oocyte developmental stages in addition to postovulatory follicles and demonstrates the potential for oocyte size frequency distribution to act as a proxy for ovarian developmental stage and future maturity assessments. Importantly, it provides the first histological evidence that Pacific halibut have a group‐synchronous ovarian developmental pattern with determinate fecundity and support for their batch‐spawning strategy.

Size frequency, length-weight relationships (LWRs), and length-length relationships (LLRs) for an estuarine fish Taenioides cirratus (Blyth, 1860) from the Noakhali coast, Bay of Bengal was studied. Specimens were caught with the fixed purse net of two mesh sizes (0.2 to 0.5 in. and 2.0 to 2.5 in.) from March to July 2019. The maximum total length for male T. cirratus (36.2 cm) reported in this study is a new record for this species. The length-weight relationships for male, female, and unsexed T. cirratus was highly significant (p

Forest disturbances have been altering the ecological properties of ecosystems; meanwhile, disturbance events of varying sizes create different structures and functions for a forest landscape. Ther...

Secondary productivity is the formation of biomass of heterotrophic organisms in units of time including biomass that is lost in a certain time unit. The Crambidae family is an insect that has aquatic larvae and will become an air insect after the larval phase. This species has the potential to become a pest for agriculture. The study was conducted in October 2019 for one month. The Crambidae family species found consists of two species, Petrophila sp. and Elophila sp. The abundance of Crambidae during the study ranged from 100 ind/m2 to 422 ind/m2. Secondary productivity was analyzed by the size frequency method. The secondary productivity of the Crambidae family in Cigambreng river waters for one month was 47.7915 g/m2/month, the biomass formed was 14.9669 g/m2 and the P/B ratio was 3.1931.

Aims: To assess the aquaculture potential of endogenous species in their habitat for domestication and preservation. Study Design: Growth performances of fish caught was analyzed by family, species, sex and month. Place and Duration: This study was conducted from April 12 to June 28, 2016 at CREVS (Cameroon Reptiles and Ecosystems Valorization Society) located in the District of Yabassi, Department of Nkam, Coastal Region of Cameroon. Methodology: A total of 160 fishes were collected by quantitative sampling for 3 months in the Nkam River. Results: It appears that two families of fish were recorded: the Cyprinidae (Labeo sanagaensis) and the Cichlidae (Tilapia cameronensis, Sarotherodon galilaeus sanagaensis, Sarotherodon nigripinnis dolloi, Tylochromis sudanensis, Hemichromis elongatus, Tylochromis trewavasae and Chromidotilapia gutheri gutheri). L. sanagaensis recorded the highest relative abundance (30%) against 3.13% (C. gutheri gutheri). Large fish were recorded in the majority of species in males, except in T. trewavasae and H. elongatus. The average total length was 23.71 ± 8.31 cm and the average total weight was 266.11 ± 200.96 g. Size frequency distribution of fish was bimodal with a large mode at size 20 cm and a small at size 36 cm. Small fish were abundant in catches especially in S. nigripinnis dolloi and C. gutheri gutheri. The allometric coefficient b of the weight-length relationship averaged 3.01 ± 0.87. The fish presented three types of growth: isometric, positive and negative allometric, and the condition factor K was greater than 1. Conclusion: It was concluded that these fish species could in general be potential candidates for domestication.

Rocks around the InSight lander were measured in lander orthoimages of the near field (

Stock assessment is necessary to understand the status of fishery stocks. However, for the data-poor fishery, it is very challenging to assess the stock status. The length-based Bayesian biomass (LBB) technique is one of the most powerful methods to assess the data-poor fisheries resources that need simple length frequency (LF) data. Addressing the present gap, this study aimed to assess the stock status of three sardines (Sardinella fimbriata, Dussumieria acuta, and D. elopsoides) in the Bay of Bengal (BoB), Bangladesh using the LBB method. The estimated relative biomass for S. fimbriata was B/B0 &lt, BMSY/B0, indicating the overfished biomass, while the assessed B/B0 &gt, BMSY/B0 for D. acuta and D. elopsoides indicates healthy biomass. Additionally, for S. fimbriata, the length at first landing was smaller than the optimum length at first landing (Lc &lt, Lc_opt), indicating an overfishing status, but a safe fishing status was assessed for D. acuta and D. elopsoides (Lc &gt, Lc_opt). Therefore, increasing the mesh size of fishing gears may help to ensure the long-term viability of sardine populations in the BoB, Bangladesh.

Simple Summary Feed costs are the most important in swine production. Precise determination of nutritional values of pig diets can help reducing feed costs by reducing security margins for nutrients and therefore provide a more sustainable swine production. In commercial farms, pigs have free access to feed and eat with no limitation according to their natural behaviour. In contrast, during digestibility trials, pigs are restricted in their daily intake of feed, which is distributed in a limited number of meals. The number of meals per day and the amount of feed consumed daily can affect the digestibility of the nutrients, the transit time and the metabolism. To reduce feed costs, by-products are frequently added to diets. Most by-products are rich in dietary fibre, which are known to have negative effects on digestibility. Enzymes can be supplemented in the diet to counteract the negative aspects of dietary fibre, but their efficiency can vary depending on the number of meals per day and the amount of feed consumed daily. Abstract Nutritional values of ingredients have been and still are the subject of many studies to reduce security margins of nutrients when formulating diets to reduce feed cost. In most studies, pigs are fed a limited amount of feed in a limited number of meals that do not represent how pigs are fed in commercial farm conditions. With free access to feed, pigs follow their intrinsic feeding behaviour. Feed intake is regulated by satiety and satiation signals. Reducing the feed intake level or feeding frequency can affect digestibility and transit time and induce metabolic changes. To reduce feed costs, alternative ingredients that are frequently rich in dietary fibre are added to diets. Fibre acts on the digestion process and transit time by decreasing energy density and causing viscosity. Various analyses of fibre can be realised, and the measured fibre fraction can vary. Exogenous enzymes can be added to counteract the effect of fibre, but digestive tract conditions, influenced by meal size and frequency, can affect the efficiency of supplemented enzymes. In conclusion, the frequency and size of the meals can affect the digestibility of nutrients by modulating gastrointestinal tract conditions (pH and transit time), metabolites (glucose and short-chain fatty acids) and hormones (glucagon-like peptide 1 and peptide tyrosine tyrosine).

This study investigated the effect of installing underwater light-emitting diode (LED) lights in different locations (close and distant to the trap entrance) and orientations (normal and upside down direction) inside baited traps targeting snow crab (Chionoecetes opilio) off the coast of Newfoundland and Labrador, Canada. Four experimental treatments were evaluated in comparison with traditional baited traps (control). Our results showed each of the experimental treatments produced significantly higher (39%–57%; 48% on average) catch per unit effort (CPUE) compared to the control traps, with no significant differences for both legal and sublegal-sized crab among the different experimental treatments. Longer soak times significantly increased the CPUE of the illuminated traps, but did not affect the catch rate of the control traps. Our results also indicated crab size frequency distributions were independent of experiment treatments. Our results suggest that fishing enterprises could improve their catching performance by adding LED lights to their traps, but the location and orientation of the lights appears unimportant. Keywords: LED, Crab trap, CPUE, Inshore fishery, Catchability

Independent dating of closely-spaced moraines on the west Breiðamerkurjökull foreland is used to test the accuracy of the size frequency (SF) and largest lichen (5LL) lichenometric dating techniques. The 5LL technique derived the most accurate ages for three undated moraines within the dated sequence but growth rates and lag times produced by the two methods (5LL = 0.71 mm yr-1 and 11 years; SF = 0.64 mm yr-1 and 7 years) were not significantly different. We therefore reject previous conclusions that any one technique is demonstrably inferior to the other, at least for dating glacial landforms created over the last 130 years in SE Iceland. Comparisons of climate trends and recession rates indicate that air temperature anomalies, particularly those of the summer, are the strongest driver of glacier retreat. No clear relationship between NAO trends and glacier retreat were identified, although a positive and/or rising trend in NAO is associated with the slowing of ice retreat overall, and the marked readvances of the mid-1950s, mid-1970s and mid-1990s are all coincident with positive and/or rising NAO 5yr moving averages. Summer and annual temperature trends, not the NAO, clearly show that recent accelerated global warming is driving the marked recession of the period 1995-2015. Over the last 100 years temperature has been the major driver of glacier terminus oscillations at west Breiðamerkurjökull but it is clear that extreme decreases in winter precipitation (i.e. 1960-73) have the potential to increase retreat rates significantly even during times of below average annual temperatures.

The Pareto-lognormal frequency distribution, which can result from multifractal cascade modeling, previously was shown to be useful to describe the worldwide size-frequency distributions of metals including copper, zinc, gold and silver in ore deposits. In this paper, it is shown that the model also can be used for the size-frequency distributions of these metals in Canada which covers 6.6% of the continental crust. Like their worldwide equivalents, these Canadian deposits show two significant departures from the Pareto-lognormal model: (1) there are too many small deposits, and (2) there are too few deposits in the transition zone between the central lognormal and the upper tail Pareto describing the size-frequency distribution of the largest deposits. Probable causes of these departures are: (1) historically, relatively many small ore deposits were mined before bulk mining methods became available in the twentieth century, and (2) economically, giant and supergiant deposits are preferred for mining and these have strongest geophysical and geochemical anomalies. It is shown that there probably exist many large deposits that have not been discovered or mined. Although overall the samples of the size-frequency distributions are very large, frequencies uncertainties associated with the largest deposits are relatively small and it remains difficult to estimate more precisely how many undiscovered mineral deposits there are in the upper tails of the size-frequency distributions of the metals considered.

We are preparing a telescope system to carry out a survey of detection and analysis of lunar impact flashes. In the framework of this project, here we present all necessary methods to automatically identify these luminous events, their lunar impact coordinates, the origin of the impacting meteoroids, as well as the estimation of their physical properties such as mass and size. We tested our methods against confirmed impact events and constructed the meteoroid size frequency distribution of impactors using literature data of the last 20 years. In addition, we present the first lunar impact event observed from the Observatoire de la Cote d’Azur that was detected during the testing phase of our project.

The scaling of events in geomorphology relates the magnitude of an event to its frequency. The size-frequency distributions of landslides have been found to follow a power-law scaling. However, the scaling of lakes formed by the deposition of landslides in the river bed received less attention. In this study, we simulate landslide occurrence, their runouts and the resulting lakes and observe that landslide-dammed lakes also follow a power-law scaling, although the scaling relationship of the landslides does not predict the scaling of the landslide-dammed lakes. A rollover is present in both distribution, and its location depends on the resolution of the topographic input data.We find that cumulative density plots are the most appropriate to highlight the influence of glacial imprint on landslide scaling, and that fluvial landscapes present results following more closely the power-law scaling. However, since lake volume is influenced by valley shape, and can be inferred from drainage area as well as landslide size, its scaling cannot be directly explained by glacial imprint and landslide scaling.Thus, among the 8 mountain ranges investigated, the Southern Alps of New Zealand and the Tibetan Plateau of Wenchuan present similar distributions with a high amount of big lakes (> 10⁸ m³), while the Central Mountain Range of Taiwan exhibit a similar pattern to the Canadian Rockies and European Alps. The Japanese Alps, Mendoza Andes and Cordillera de Talamanca present much smaller lakes.

To assess microplastics abundance in the aquatic environment different filtering tools (nets, meshes and filters) are generally applied. As a result, their naturally occurring size-frequency distributions are altered because of removing of items smaller than the mesh size. This hampers comparison of the results between studies utilized filters and nets of different mesh size. To assess the process of MPs generation and filtration, a stochastic model of macroplastic destruction coupled with the model of MPs filtration on the net was proposed. The stochastic model of macroplastic destruction incorporates empirical parameterizations of fracture position and fracture probability as a function of particle shape. The model sensitivity was tested in respect to the input parameters: the initial number of particles, the initial size of the macroparticles, the number of fracture steps (number of generations, i.e. the final ‘age’ of the particles), and the number of independent ‘sources’ in the final particle set.The simulation results were compared with the available publications as well as with the data collected at Lake Onego. This allowed us to achieve qualitative agreement between the modelled and the observed distributions based on the similarity of the shape of size-frequency distribution curve in log-log scale.Large particles, which have all three dimensions larger than the mesh size, are retained by the net efficiently. For others the probability of particle retention by the net depends on the particle shape, smallest and largest dimensions, and particle orientation in space.To simulate the actual filtration process on the net, a mathematical model of filtration process was developed. The model passes a given set of three-dimensional particles (in quasi-elliptic approximation) through a two-dimensional net with a given cell size. Randomly given parameters determine the position of a particle in space, the size of its projection on the two-dimensional plane (net), and the position of the particle centre with respect to the corners of the cell (net). The results of plastic breaking simulation were coupled with a stochastic MP particle filtration model. This allowed us to show qualitatively how the shape of size-frequency distribution of MP particles is altered after the filtering through the net with a mesh size close to the lower boundary. This information can be used to compare the results obtained in studies utilized different neuston nets and filters, which is one of the most relevant tasks in the assessment of environmental contamination by microplastics on a global scale.The study was supported by the Russian Science Foundation grant number 19-17-00035.

Difflugia australis, first described by Playfair (1918), has a unique morphotype. However, in the absence of morphometric data, it has not yet been reliably classified within the largest testate amoeba genus Difflugia. In this study D. australis collected from a subtropical reservoir in southeast China was investigated by means of light and scanning electron microscopy. Basing on biometrical data, we provide an improved diagnosis of this little known species. Difflugia australis is different from other similar congeners (i.e., D. bacillariarum Perty, 1849 and D. elegans Penard, 1890) mainly by the combination of the following features: the shell is broadly ovate, with rounded dome and convex sides converging down to a very short distance from the aperture and diverging suddenly into a short rim (collar). It is usually more or less asymmetrical, with one side being more dilated than the other. The shell surface is slightly smooth, composed of flat siliceous plates of irregular shape and size, mixed with fine grains; microbial spores of comparable forms are spread on the shell surface; particles are often interspersed with a network of organic cement with unique mesh pattern; one (sometimes two) slanting spine-like posterior end of the shell is variable in form; collar is mainly formed by small plates of equal size. The dimensions of the shell are: total shell length 88–106 µm; shell width 53–88 µm; aperture diameter 19–28 µm; collar height 3–6 µm; spine length 3‒23 μm. The size frequency distributions of both total shell length and shell width indicate that it is a size-monomorphic species with low variability.

An asteroid’s history is determined in large part by its strength against collisions with other objects1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5. In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7. It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu’s metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years. Analysis of the size and depth of craters on boulders on the asteroid (101955) Bennu indicates that Bennu has been in near-Earth space for 1.75 ± 0.75 million years.

IntroductionAsteroid (65803) Didymos is an S-type [1] Apollo binary system characterized by a 780±30 m size primary, called Didymos, and a 164±18 m size secondary, called Dimorphos, orbiting at a distance of ~1.19 km [2]. The primary rotation period is 2.26 h [2], close to the 2.2 h disruption spin barrier [3], while the period of revolution of Dimorphos around the primary is 11.9217+0.0002 h [4]. This asteroid has been selected as the target of the Double Asteroid Redirection Test (DART, [5]), whose main goal is to impact Dimorphos at a speed of 6.6 km/s on September 30, 2022, thereby demonstrating the kinetic impactor technique and evaluating the resulting impulsive deflection.The scientific camera onboard DART is called DRACO, i.e. the Didymos Reconnaissance and Asteroid Camera for Op-nav [6]: its main goals are to image Didymos for optical navigation, to resolve the two bodies and support the spacecraft autonomous navigation to the target, and to locate the impact site precisely and characterize its local surface features. To complement such observations, the Light Italian Cubesat for Imaging of Asteroids (LICIACube, [7]) will be released from DART ten days before the impact, and autonomously guided through a flyby with closest approach distance of ~55 km from the target. LICIACube cameras LEIA (LICIACube Explorer Imaging for Asteroid - narrow angle camera) and LUKE (LICIACube Unit Key Explorer – wide angle camera) will then safely witness the redirection test in-situ, while its crater, as well as the ejecta and plume are being formed.Boulders SFD on Didymos systemBoulders/large blocks on asteroids are mainly interpreted as produced by target fragmentation and excavation due to high-velocity impact processes. They are the largest fragments excavated during an impact and are typically found within the crater or in its proximity, because they have not reached the escape velocity [8]. Instead, on rubble-pile asteroids boulders (typically the largest ones) are products of the reaccumulation process that formed the minor body itself, and may not be correlated to the observed craters [9]. For both cases, these blocks provide information on impact cratering processes occurring on low gravity bodies or on their parent body disruption event: their size-frequency distribution (SFD) fitting indices are therefore pivotal to provide hints on the fragment/boulder formation and/or degradation processes.Deriving boulder SFD and the corresponding power/exponential-law indices has been an important scientific topic addressed in several fly-by and orbital missions to minor bodies [e.g. 10-12]: it will be accomplished on the Didymos system as well.Four minutes before the impact the last image that contains all of Didymos will be taken by DRACO, with an expected spatial scale of 7 m/pixel. 120 seconds before impact, the last DRACO image containing any part of Dydimos will be taken, with a maximum resolution of 3.5 m [13]. DRACO will image all of Dimorphos ~50 cm/pixel ~17 seconds before impact and plans to return at least one higher-resolution image before impact. These final image(s) will have pixel scales At closest approach (CA), LICIACube/LEIA will image the surface of Dimorphos at 1.4 m/px [7]. If the DART crater will be observed through LEIA (it may be close to the limb during CA, hence the challenging imaging condition), we will be able to identify all boulders larger than 4.0-7.0 m located on the impacted side of Dimorphos, discerning those that have been generated/fragmented/moved after the DART impact from the ones previously imaged through DRACO. In addition, LEIA will image the non-impacted side of Dimorphos (not observed by DRACO) with resolutions ranging from 1.5 to 5 m: this will enable the characterization of the boulders SFD of the secondary down to 4.5 m.By comparing both the pre-, post- and non-impacted surface areas we will have the unique opportunity to witness how the boulders SFDs and densities/m2 will change as a result of a well characterized, hypervelocity impact. We will therefore test if the generation of a crater results in a different power-law distribution of boulders than the one observed on other S-type asteroids, such as (433) Eros and (25143) Itokawa [8,9], as well as recently observed carbonaceous asteroids, (101955) Bennu [12] and (162173) Ryugu [15].Acknowledgments: This research was supported by the Italian Space Agency (ASI) within the LICIACube project (ASI-INAF agreement AC n. 2019-31-HH.0).References: [1] de León, J. et al. (2010) Astron. Astrophys, 517, A23. [2] Naidu, S.P. et al. (2020) Icarus, 348, 113777. [3] Pravec P. and Harris A.W. (2000) Icarus, 148, 12-20. [4] Pravec, P. et al. (2006) Icarus, 181, 63. [5] Cheng A. F. et al. (2016) Planet. Space Sci., 121, 27-35. [6] Fletcher, Z.J. et al. (2016) 3rd Inst. Planetary Missions, 4043. [7] Dotto, E. et al., (submitted), Planet. Space Sci. [8] Thomas, P.C., et al. (2001) Nature 413, 394. [9] Michikami, T. et al. (2008), Earth Planets Space, 60, 13-20. [10] Lee, S.W., et al. (1986) Icarus 68, 77. [10] Geissler, P., et al. (1996) Icarus 120, 140. [11] Pajola, M. et al. (2015), Astron. Astrophys. 583, A37. [12] DellaGiustina, D. et al. (2019), Nat.Astron. 3, 341-351. [13] Cheng, A. F. et al. (2018) Planet. Space Sci., 157, 104-115. [14] Barnouin, O. et al. (2019). LPSC 50 abst. 2448. [15] Watanabe, S. et al. (2019), Science, 364, 6437, 268-272.

1. Introduction To estimate a size-frequency distribution (SFD) of any population of small bodies it is necessary to compensate the observational selection effects, which generally favor larger and brighter objects. For a mixed population, made up of asteroids and comets, as expected for the population of interstellar objects (ISOs), the discovered population should be also significantly biased toward cometary objects, which makes it difficult to estimate even the basic properties of this population. Therefore, the ISO SFD was completely unconstrained [1], until very recent work by Bolin et al. [2]. We have investigated the orbital distribution of ISOs, observable by the future wide-field National Science Foundation Vera C. Rubin Observatory (VRO). The results show that among the asteroidal ISOs, there should be an excess of retrograde orbits among the observed objects [3]. We found that this may be due to the observational selection effects, known as Holetschek’s effect [4]. Interestingly, a level of retrograde orbit excess depends on the SFD of the ISOs, suggesting that the ratio between the prograde and retrograde ISOs observable by the VRO could be used for estimation of the SFD of the underlying true population. 2. Holetschek’s effect According to this effect, objects which reach perihelion on the side of the Sun opposite to the position of the Earth are less likely to be discovered. This is because in this configuration objects are both, too close to the Sun (small elongation), and further away from the Earth (fainter). Therefore, a probability for an object to be discovered depends on the difference Δλ between the heliocentric longitude of the Earth and that of the object at the time of the perihelion passage of this object. This is illustrated in Fig. 1. Figure 1 - Constellation related to Holetschek’s effect. Quantity Δλ is the difference between the heliocentric ecliptic longitudes of an interstellar object and the Earth, at the epoch of the object’s perihelion passage. 3. Orbital distribution of ISOs To investigate the influence of Holetsechek’s effect on ISOs, we generate their synthetic population and simulate their ephemerides over a period of 10 years, in order to select those which may be observed by the VRO, based on the nominal characteristics of this survey. We found that Holetschek’s effect is more pronounced for objects on prograde than for those on retrograde orbits. This is obvious from Fig. 2 in which are shown distributions of Δλ separately for prograde and retrograde objects. Figure 2 - The normalized histograms of Δλ of the detectable objects. The figure shows separately objects on direct (ii>90 deg) orbits. The vertical plane denotes objects which pass through their perihelions while they are on the same heliocentric ecliptic longitude as the Earth. The observed asymmetry is likely due to Holetschek’s effect. 4. Future prospect Different sensitivity of prograde and retrograde objects to the effect results in asymmetry of distribution of the orbital inclinations of the detectable population. On the other hand, Holetschek’s effect mostly affects small bodies, while for larger objects (of the order of several km) it is almost negligible. Since populations with steeper size distribution have larger portion of small objects, they are more subjected to this effect, resulting in a more pronounced asymmetry of the distribution of orbital inclinations. Our results show that a retrograde/prograde orbits ratio and median orbital inclination of the detectable population is correlated with the SFD slope of the generated population of ISOs. Therefore, these parameters of the discovered population of ISOs could, in turn, be used to estimate the SFD of the underlying true population. Alternatively, based on an available estimation of the SFD of interstellar objects [2], the expected excess of retrograde orbits could be calculated. References: 1. Engelhardt T., Jedicke R., Vereš P., Fitzsimmons A., Denneau, L., Beshore E., Meinke B.: 2017, AJ, 153, 133 2. Bolin B.T., et al., 2020, AJ, 160, 26 3. Marčeta D., Novaković B., 2020, MNRAS, doi:10.1093/mnras/staa1378 (arXiv:2005.10236) 4. Holetschek J., 1891, Astronomische Nachrichten, 126, 75

In this research paper, it is attempted to study the grain size distribution of heavy minerals and their distribution pattern along with chemical characteristics of four samples collected from Bhrahmagiri coast of Odisha. The grain size distribution of as it is samples and heavy minerals are carried out. Size frequency mode of 300 and 212 μm are more significant for as it is samples. Whereas, size analysis of heavy minerals show size frequency mode of 212 μm. All the four samples are found to contain higher percentage of magnetic heavies.

The current knowledge about the ecological effects of microplastic (MP) remains limited, and to-date ecotoxicity tests often utilize standard microplastic with one or two distinct size classes and expose the organisms to unrealistically high MP concentrations. We exposed the marine diatom Phaeodactylum tricornutum to microplastic particles of a mimicked realistic size frequency distribution complemented with serial experiments with distinct size classes. To do so, we exposed this diatom to a concentration series of different sized polyethylene (PE) microbeads (sizes: 10–106 µm; 1.25 ×102–1.25 ×107 particles/L) in a 72-h growth inhibition test. No effect on the growth of P. tricornutum by virgin PE microbeads up to 1.25 × 107 particles/L (or 499 mg/L), indicating environmentally relevant concentrations and sizes of MP does not alter the growth of marine diatoms. Results of smaller sized MPs (10–20 µm) did not differ from those obtained with larger MPs (90–106 µm) and mix sized MPs (10–106 µm), i.e. no impact on the microalgae growth. As a pioneer work, our results contribute with high quality dose-response data to an improved risk assessment of microplastic under realistic present and future marine MP pollution.

Dust devils play a major role on Mars, providing a significant proportion of the total dust removal from the surface and its injection into the atmosphere, thus largely determining the overall radiative regime and the climatic state of the Martian atmosphere. The amount of dust lifted to the atmosphere by a population of dust devils is determined by the number density of dust devils (their number per unit area) and by their size-frequency and intensity-frequency distributions. Using the Abel transform, a two-step methodology has been developed to determine the marginal statistical distributions of convective vortices, including dust devils, on their intensity (pressure drop in the vortex center) and size (diameter), based on statistics of transient pressure drops recorded when the vortices pass near a pressure sensor placed on the surface of the planet. In a first step, if the pressure profile within the vortex is realistically modeled then the intensity-frequency distribution in the population of vortices can be inferred from the statistics of peak pressure drops recorded alone. If the observed statistics can be approximated with a truncated power-law distribution and in the absence of an apparent correlation between the vortex diameter and the maximum pressure drop at its center, then the measurements provide an unbiased power-law estimate of the actual intensity-frequency distribution. In a second step and in a practically important case when the distribution of vortices on their intensity follows the power law, the problem of determining the vortex size-frequency distribution is solved from data obtained in pressure time-series surveys. This two-step technique has been applied with success to Mars Science Laboratory (MSL) convective vortices.This work was supported by the Presidium of the Russian Academy of Sciences, project no. 19-270. The method of inferring the vortex size-frequency distribution was developed with the support from the Russian Science Foundation (grant no. 18-77-10076).References:Kurgansky M.V. On the statistical distribution of pressure drops in convective vortices: Applications to Martian dust devils // Icarus. Volume 317, 1 January 2019, Pages 209-214. https://doi.org/10.1016/j.icarus.2018.08.004.Kurgansky M.V. On determination of the size-frequency distribution of convective vortices in pressure time-series surveys on Mars // Icarus. Volume 335, 1 January 2020, 113389. https://doi.org/10.1016/j.icarus.2019.113389.

Reproductive biology of Atlantic chub mackerel (Scomber colias) was studied based on samples from commercial catches in M'diq Bay, Morocco. Females predominated in the total catch (54%), their size at first maturity being 19.19 ± 0.43 cm TL. A minimum landing size (MLS) of 21 cm is suggested. The oocyte size frequency distribution and histological analysis confirmed that S. colias is a species with an indeterminate fecundity. The batch fecundity was estimated as 18,452–131,642, with a mean of 60,022 oocytes. The relative batch fecundity was 157–360, with a mean of 279 eggs g−1.

A total of 161 specimens of C. sapidus were collected during the fishing season from November 2016 to July 2017, of the 100 specimens were males (62.1%) and 61 were females (37.9%). The number of obtained specimens has seasonally fluctuated. The highest number of individuals was 67 (41.6%) obtained during spring, compared with the minimum number of 28 individuals (17.4%) collected in summer. The present results showed that 87.3% of the population fell within 75 and 124.9 mm CW and was represented by two modes comprising the sub adults and adults. There were seasonal changes in the size frequency distribution of pooled samples of this species. Males over-dominated females and were represented by the general sex ratio of 1:0.61 males: females. This ratio was tested using the Chi-square (X2) Test for Goodness (P

The main objective of this study was to determine reproductive strategy including major spawning season of tropical abalone (Haliotis asinina) from southern Lombok waters, Indonesia. Gonad bulk index, maturity stages and oocyte size frequency distribution were applied to document gonadal development and major spawning season. The results of this study show that H. asinina in southern Lombok waters displayed year-round spawning with a high proportion occurring in August - November, when gonad index dropped to a lower level and high proportion of partly spawned and/or spent ovaries occurred in the population. Gonad development and spawning in males and females occurred synchronously. The correlation between gonadal development and environmental factors are described and discussed.

Previous studies have estimated the ages of lunar lobate scarps, some of the youngest tectonic landforms on the Moon, based on the estimated life-times of their fresh morphologies and associated small graben, using crater degradation ages, or via buffered and traditional crater size-frequency distribution (CSFD) measurements. Here, we reexamine five scarps previously dated by Binder and Gunga (1985) with crater degradation ages to benchmark the evaluation of both the buffered and traditional CSFD approaches for determination of absolute model ages (AMAs) at scarps. Both CSFD methods yield similar ages for each individual scarp, indicating that fault activity not only can be measured on the scarp itself, but also in the surrounding terrain – an indication that tectonic activity causes surface renewal both adjacent to and even kilometers distant from scarps. Size-frequency variations in the regions surrounding the scarps are thus useful for studying the extent and severity of the ground motion caused by coseismic slip events during scarp formation. All age determination approaches continue to indicate that lunar lobate scarps were active in the late Copernican, with some scarps possibly experiencing activity within the last 100 Ma.

The current study provides long-term catch-rate, biological and feeding data for smooth hammerhead sharks, Sphyrna zygaena, caught in South Africa’s KwaZulu-Natal bather protection programme. In total, 2 512 S. zygaena were caught in net installations between 1978 and 2014, and 72 S. zygaena were caught on drumlines between 2007 and 2014. There was no significant log-linear year trend in the net catch rate over time (slope = 0.0054, t = 1.808, p = 0.07). However, there was a significant temporal increase in mean size of the captured sharks (slope = 0.0012, t = 3.502, p < 0.001). A quasi-Poisson generalised additive mixed model showed that increasing latitude, winter months, colder sea temperatures and the deployment of drumlines all had a significant positive effect on the catch rate of sharks in nets. The size frequency of the catch was unimodal, with significantly more females caught in the nets and more males on the drumlines. The majority (93.1%) of all sharks caught were immature and measured between 80 and 120 cm precaudal length. Teleosts and cephalopods dominated the sharks’ diet in terms of all dietary indices. The prey species consumed indicate that immature S. zygaena are feeding primarily within the pelagic zone of shallow coastal habitats.Keywords: CPUE, drumlines, generalised additive mixed model, length frequency, sex ratio, shark nets, stomach contents

Diamond size frequency distribution (SFD) curves, combined with the associated dollar per carat per size class, play an important role in the diamond industry. Value per size class is unique for each deposit and typically varies from less than a dollar per carat to several thousands of dollars per carat for special stones. Recovery of large stone therefore contributes significantly to the bottom line of a large diamond producer. While the design of the process plant should prevent damage and possible breakage of large stones, it should also ensure adequate liberation of the finer diamonds. Innovative solutions are required to protect and recover type I and II diamonds if prominent within the resource. X-ray transmission (XRT) sorting presents the opportunity to develop flow sheet designs that incorporate a balance between exploitation of the resource and process efficiency, as well as practical capital and operating costs. This paper serves to illustrate the role and application of SFD curves in determining optimum cut-off and re-crush sizes within the flow sheet of a large diamond producer. A thorough understanding of the unique technical and economic aspects of a deposit provides the basis from where new and innovative technologies can be proposed, allowing mining companies to maintain and improve profit margins. It highlights the results of various plant trials and newly commissioned XRT sorters for larger size fractions. It also provides recommendations for future applications of XRT machines in the diamond process flow sheet.

The review and new measurements are presented for depth/diameter ratio and slope angle evolution during small (D < 1 km) lunar impact craters aging (degradation). Comparative analysis of available data on the areal cratering density and on the crater degradation state for selected craters, dated with returned Apollo samples, in the first approximation confirms Neukum’s chronological model. The uncertainty of crater retention age due to crater degradational widening is estimated. The collected and analyzed data are discussed to be used in the future updating of mechanical models for lunar crater aging.

Many Mesozoic formations have yielded substantial dinosaur dominated ichnofaunas, which help characterize coeval communities. When compared with dinosaurian skeletal data (faunal lists) from the same and /or coeval deposits, the completeness and diversity of trace and body fossil records may be shown to be of equal or quite different value for paleoecological analysis and interpretation. The size frequency distribution for >1,170 trackways from 17 theropod dominated Late Triassic-Cretaceous tracksites from North America and China is compared to the data used from the skeletal record to test the Ontogenetic Niche Shift (ONS) model. While track and body fossil databases are different in some regards, they are similar in others, notably in providing coherent size frequency data and useful taxonomic/ichnotaxonomic diversity estimates on a formation by formation or site by site basis. The cumulative, ichnological size frequency data, can be compared with the small, intermediate, and large or megatheropod body mass categories ( 1000 kg) used in ONS analysis, and supports the conclusion that ~50%, 31% and 19% respectively of the track sample fall into these three categories. Thus, theropod track abundance is inversely proportional to size. Despite the small proportion of megatheropods track data reveals an increase in the maximum size of theropods through the Mesozoic.