Vertical Nets Research Articles

Spatial distribution and circadian locomotor activity of invasive armored catfish (Loricariidae) in the freshwater and brackish water.

Invasive suckermouth armored catfish Pterygoplichthys spp. successfully spread during one decade into many river systems of Vietnam. Wide and rapid invasion of armored catfish might be associated with using brackish water in estuaries to spread from one river system to another. The first goal of our study was to assess the horizontal and vertical distribution of invasive fish in freshwater (Da Rang River) and in brackish water (Da Rang River estuary) associated with circadian rhythm. In the both sampling locations, fish were mainly caught at nighttime at the bottom and near the surface using the net traps and vertical nets. In estuary, fish were caught in the net traps with distance 2.0-7.5 m from the right or left banks where water was predominantly fresh. In freshwater of the Da Rang River, fish were often caught near the left bank with gravel and stone substrate. The second goal of our study was to experimentally evaluate the circadian (12 hours of the night and 12 hours of the day) rhythm of locomotor activity (LA) of fish. Fish from different freshwater locations (Am Chua canal and Da Rang River) had a similar diurnal dynamic of LA with mostly movements (77-83% of total diurnal LA) at nighttime (18:00-6:00, GMT+7) at the end of the wet season. Armored catfish from the brackish water location (Da Rang River estuary) also were mostly active (76% of total diurnal LA) overnight. However, fish from freshwater and brackish water had difference in the timing of behavioral activity. Fish LA from estuary was significantly lower than LA of fish from freshwater locations during 18:00 to 21:00 before low tide. The results of our field and experimental studies established that armored catfish in estuary moved in horizontal and vertical planes predominantly at nighttime. Tide level regulates locomotor activity of invasive fish and could influence on the possibility of their spreading through the estuary.

Effect of Growth of Filamentous Algae on the Thallus Surface of Kappaphycus alvarezii (Doty) L.M.Liao (Rhodophyta)

Filamentous algae usually form dense or sparse masses that float freely or attach to other plants, rocks, or other hard substrates. Many filamentous algae attach to <i>Kappaphycus alvarezii</i> which is cultivated by farmers in the tropics. This study explained the effect of filamentous algae attachment on the morphology and growth of <i>K. alvarezii</i>. This research was conducted in one of the cultivation locations on the coast of Tanjung Tiram, southeast Sulawesi Province, Indonesia. This study used a vertical net to cultivate <i>K. alvarezii</i> thallus samples. Vertical nets are used to protect <i>K. alvarezii</i> from fish pests and attached algae. We analyze the attachment rate of filamentous algae about the morphology and growth of <i>K. alvarezii</i> thallus within 40 days. The results showed two dominant filamentous algae species, Elachista flaccida and Chaetomorpha crassa. The density of E. flaccida occurred on day 10, with a density level reaching 12 individuals/m<sup>2</sup> and increasing on day 20 to 45 individuals/m<sup>2</sup>. Chaetomorpha crassa species also appeared at 2.24 g/m<sup>2</sup> on day 20, decreased to 0.63 g/m<sup>2</sup> on day 30, and disappeared on day 40. The torn surface thallus was seen to occur on day 2.324 mm<sup>2</sup> on day ten and decreased by 104 mm<sup>2</sup> on day 20. Attachment of filamentous algae slightly impacted the growth of <i>K. alvarezii</i> thallus, although the correlation analysis did not show a significant effect. Another correlation analysis explained no significant correlation between multiple attachments of filamentous algae and torn surface thallus of <i>K. alvarezii</i>.

Epiphyte attachment preference on Eucheuma denticulatum (Rhodophycea) Thallus and Vertical Net

The attachment of epiphytes on culture equipment and seaweed thalli has proven to be one of the factors preventing Eucheuma denticulatum growth. This research aimed to clarify epiphyte preference for E. denticulatum thallus and culture equipment by using vertical nets. Vertical net is a cultivation technology that protects seaweeds from herbivorous pests (fish and turtles). This research was conducted at Tanjung Tiram Coast, one of seaweed cultivation areas in Southeast Sulawesi Province, Indonesia. This research used vertical nets and E. denticulatum thalli. The study took place at 3 stations, each using 3 tools and 3 replications. The results showed that there were 7 species of epiphyte attaching to the vertical net equipment and 6 species attaching to the thalli of E. denticulatum. The densities of epiphytes attaching to the vertical net equipment and E. denticulatum thalli were 110 ind./cm2 and 250 ind./cm2 on average, respectively. Statistical analysis showed no significant difference in density between the epiphytes attached to the vertical net equipment and those attached to the E. denticulatum thalli. They also showed that the epiphyte density insignificantly influenced the overall seaweed weight. Correlation analysis showed a significant correlation between the abundance of epiphytes attached to the vertical nets and brightness.

Collateral damage from agricultural netting to open‐country bird populations in Thailand

AbstractNets are used across a wide variety of food production landscapes to control avian pests typically resulting in deaths of entangled birds. However, the impact of nets on bird populations is a human–wildlife conflict that remains mostly unquantified. Here, we examined the scale of netting in the central plains of Thailand, a region dominated by ricefields, among which aquaculture ponds are increasingly interspersed. Nets/exclusion types, number of individual birds and species caught were recorded on 1312 road‐survey transects (2‐km length × 0.4‐km width). We also interviewed 104 local farmers. The transect sampling took place in late‐September 2020, and from December 2020 to April 2021. Each survey transect was visited only once. We found 1881 nets and barriers of parallel cords on 196 (15%) of the transects. Counts of nets and barriers were ~13 times higher than expected in aquaculture ponds based on their areal proportion, and vertical nets were the most commonly observed type (n = 1299). We documented 735 individuals of at least 45 bird species caught in the nets and parallel cords, including many species not regarded as pests. Approximately 20% of individuals caught in ricefields and 95% at aquaculture ponds were non‐target bycatch. Our interviews suggested that 55% of respondents thought nets were ineffective while only 6% thought they were effective. We suggest imposing a ban on netting, considering other mitigation strategies to reduce conflicts such as promoting the use of parallel cords, and prioritizing conservation actions with community participation. Further studies should investigate the efficacy of less deleterious deterrents.

Listen But Do Not Touch: Using a Smartphone Acoustic Device to Investigate Bat Activity, with Implications for Community-Based Monitoring

The monitoring of bats across the world is mostly conducted using invasive mist-netting, whereby vertical nets are placed to capture bats mid-flight. Many studies have demonstrated how this approach causes sampling bias, is labor-intensive and increases the risk of white-nose syndrome fungus, Pseudogymnoascus destructans, transmission among bats. Increasingly, acoustic devices are being employed to collect data on bat activity and richness. Community-based monitoring is an important data collection source for bat monitoring programs in countries such as the UK (National Bat Monitoring Program), whereby walking bat transects are conducted using bat detectors. Since the launch of smartphone devices to record and auto-identify bat echolocation calls, the quality of data collection that community members can collect has increased significantly, however, this approach is seldom used to generate data in scientific studies. In our study, we have showcased how our study design paired with state of the art acoustic monitoring devices, can be applied to community-based monitoring of bats across the world. Through employing smartphone acoustic devices, we have determined how primary and secondary vegetation cover are predictors of bat species occurrence and identified the importance of riverine and deciduous swamp habitats for rare bat species in southwestern Ontario.

Seasonal variation of giant gourami (Osphronemus goramy) spawning activity and egg production in aquaculture ponds

The giant gourami Osphronemus goramy Lacépède, 1801, spontaneously spawns in captivity, making nests for egg deposition when suitable nest supports and nesting material are made available in rearing facilities. The seasonal variation in reproductive performance of the giant gourami was characterized during a 20-month experiment in two compartmentalized ponds (about 550 m2 each) at a fry production center in West Java, Indonesia. A total of 208 giant gourami broodfish were introduced in the two experimental ponds, with a sex-ratio of one male to three females in each of the 52 spawning compartments delimited by vertical nets. Nesting supports in each spawning compartment were examined every two days for the presence of eggs resulting from natural reproduction. Three performance indicators were quantified from the collected nests: spawning frequency (monthly number of spawns per female), effective fecundity (number of eggs per spawn) and egg quality (estimated from the proportion of clear living eggs in each spawn). The seasonality of giant gourami reproduction was analyzed as a function of seasonal variation in rainfall, rearing water temperature and day length. Based on a total of 413 collected spawns, the multiple linear regression models did not show any significant relationship between giant gourami spawning frequency and the three environmental variables studied. In contrast, the number of eggs per spawn was highly and positively related to rainfall (p < .0001), moderately and negatively related to water temperature (p < .001), and weaklier and negatively related to day length (p < .01). The proportion of clear eggs was positively related to day length (p < .01). Overall, this study represents one of the first comprehensive datasets on the reproductive phenology of giant gourami, and as such will be helpful in formulating broodfish management strategies for the species.

Effect of Depth on the Growth and Carrageenan Content of Seaweed Kappaphycus alvarezii Cultivated Using Verticulture Method

Seaweed of Kappaphycus alvarezii is generally cultivated by the long line method through the water surface. The verticulture method might be an alternative method by using water column. This research aimed to evaluate the effects of depth on the growth and carrageenan content of K. alvarezii which was cultivated vertically. Cultivation was carried out in the floating raft (10 x 10 m)2 contained of 36 vertical nets. The size of each net was 5 x 2 m2 whereas the depth was 0.2, 1, 2, 3, 4, and 5 m. Seaweed seedlings of 50 g was each tied to the vertical nets; the distance between the knot was 20 cm. The results showed that the depth was significantly different to the daily growth rate of K. alvarezii (p&lt;0.05) but did not affect carrageenan content (p&gt;0.05). Therefore, this method might be applied as an alternative method to optimally increase seaweed production in narrow area without affecting seaweed quality.

Assessing Deep-Pelagic Shrimp Biomass to 3000\u2009m in The Atlantic Ocean and Ramifications of Upscaled Global Biomass

We assess the biomass of deep-pelagic shrimps in the Atlantic Ocean using data collected between 40°N and 40°S. Forty-eight stations were sampled in discrete-depth fashion, including epi- (0–200 m), meso- (200–800/1000 m), upper bathy- (800/1000–1500 m), and lower bathypelagic (1500–3000 m) strata. We compared samples collected from the same area on the same night using obliquely towed trawls and large vertically towed nets and found that shrimp catches from the latter were significantly higher. This suggests that vertical nets are more efficient for biomass assessments, and we report these values here. We further compared day and night samples from the same site and found that biomass estimates differed only in the epi- and mesopelagic strata, while estimates from the bathypelagic strata and the total water column were independent of time of day. Maximal shrimp standing stocks occurred in the upper bathypelagic (52–54% of total biomass) and in the mesopelagic (42–43%). We assessed shrimp biomass in three major regions of the Atlantic between 40°N and 40°S, and the first-order extrapolation of these data suggests that the global low-latitude deep-pelagic shrimp biomass (1700 million tons) may lie within the range reported for mesopelagic fishes (estimations between 1000 and 15000 million tons). These data, along with previous fish-biomass estimates, call for the reassessment of the quantity and distribution of nektonic carbon in the deep ocean.

Determination of Optimal Planting Distance between Seed Clump on Seaweed Verticulture Method

Kappaphycus alvarezii cultivation by the verticulture method has been introduced since 2013. However, scientific studies on some technical aspects are still needed to improve the quality, quantity, and continuity of production and utilization of area in a maximum and productive manner. One of them is the planting distance between seed clumps. The purpose of this study was to determine the optimal planting distance between seed clumps on seaweed verticulture method. Seaweed was cultured using a 10x10 m2 floating raft containing 36 vertical nets of 5x2 m2/net. Seaweed seeds with an initial weight of 50 g were tied to a vertical net with a distance between knot on the verticulture net of 15 cm, 25 cm, and 35 cm. Seaweed cultivation was done for 3 cycles (1 cycle = 45 days) continuously in the cycle of planting season. The experimental units were prepared with Completely Randomized Design (RAL) with 3 replications. The results showed that daily growth rate (DGR) and carrageenan content of seaweed planted with a distance of 15 cm, 25 cm, and 35 cm between clumps were not significantly different (P&gt;0.05). However, it is recommended to apply 25 cm distance between seed clumps in the verticulture method.

Keanekaragaman, Kelimpahan, dan Sebaran Kopepoda (Krustasea) di Perairan Bakau Segara Anakan, Cilacap

&lt;strong&gt;Diversity, Abundance, and Distribution of Copepods (Crustacea) in the Mangrove Area of Segara Anakan, Cilacap.&lt;/strong&gt; Observations on the diversity of Copepods, its abundance, and its distribution in three mangrove and estuarine locations in Segara Anakan Lagoon, Cilacap, were conducted in May (dry season) and November (rainy season) 2009. This study aims to determine the relationship of diversity and abundance of Copepods with some environmental factors that affect its distribution in the dry and rainy seasons. Copepod samples were taken from Kutawaru waters, Dermaga Sleko, and Ciperet using vertical and horizontal plankton nets, day and night. They were then preserved, deposited, and identified in MZB LIPI. There were 36 species of Copepods from 18 genera and 20 families, including 10 new records. The highest species diversity of Copepods was recorded in November, while the lowest was in May. The average abundance in May was higher than in November. The diversity and abundance in Ciperet in both dry and rainy seasons were always higher than the other two sites. Acartia erythraea, A. sinjiensis and Pseudodiaptomus annandalei were found to dominate the waters especially during the dry season in May. The community composition of Copepods occupying the waters was determined by salinity, while its activity and development were determined by temperature. &lt;br /&gt;

Redes de seguridad para cierre vertical de fachadas

Among other methods, vertical safety nets on the facades of buildings during the construction stage are used in Spain as an alternative to other safety systems in order to avoid falls to a different level. There are two kinds of such nets: floor-to-ceiling nets - that secure the entire void between successive floors in structure construction stage-, and small nets what secure windows and other minor voids in later stages. Their design and requirements are not defined at present, but the AEN/CTN81/SC2/GT7 Spanish Working Group is drafting a specific regulation named Pr UNE 81651. Some members of the Civil Engineering Department of the University of Alicante, having experience in other systems of protection, have developed several finite-elements numerical models to measure and analyse mechanical variables related to a possible fall of a person over this kind of net, characterised by a kinetic energy lower than for other types. In this paper the obtained results are shown, for both large and little nets, analysing the anchorages gap, void openings at perimeter, maximum net deflection and net disposal (square/diamond) repercussion, as well as its consequences on the victim’s safety (impact factor).

Open critical area model and extraction algorithm based on the net flow-axis

In the integrated circuit manufacturing process, the critical area extraction is a bottleneck to the layout optimization and the integrated circuit yield estimation. In this paper, we study the problem that the missing material defects may result in the open circuit fault. Combining the mathematical morphology theory, we present a new computation model and a novel extraction algorithm for the open critical area based on the net flow-axis. Firstly, we find the net flow-axis for different nets. Then, the net flow-edges based on the net flow-axis are obtained. Finally, we can extract the open critical area by the mathematical morphology. Compared with the existing methods, the nets need not to divide into the horizontal nets and the vertical nets, and the experimental results show that our model and algorithm can accurately extract the size of the open critical area and obtain the location information of the open circuit critical area.

Effect of net structures on wall-free non-stationary air heat vortices

The experimental results of the influence of different net structures on the dynamics of wall-free non-stationary air vortices are presented. These vortices were produced over underlying surface of aluminum sheet due to its controlled heating from below as a result of development of unstable stratification of air. It is strictly emphasized that on the contrary to previous studies no mechanical swirling devices and/or underlying surface rotation were used for the vortices generation. We have conducted the experiments on establishing how vertical nets placed in the travel line of a sufficiently non-stationary laboratory vortex affect its dynamics. Six different patterns of behavior of vortices in the interaction with net obstacles were revealed as a result of conducted experiments. We have distinguished several fundamental mechanisms of how nets affect a non-stationary vortex. Among these mechanisms is the action of small-scale turbulence generated behind the net with large-scale turbulence of the model vortex, leading to violation of its symmetry. The generalization is performed of the data obtained concerning the influence of net structures of various geometries on the laboratory-simulated vortices of different intensities.

Heavy flooding effects on home range and habitat selection of free-ranging Iberian hares (Lepus granatensis) in Doñana National Park (SW Spain)

The Iberian hare Lepus granatensis is a common and abundant species throughout the Iberian Peninsula; however, studies documenting its ecology are scarce. Between August 1996 and September 1997, after a long drought, we studied the effects of a widespread flood on the Iberian hare ecology in ecotone pastures of Donana National Park. Hares were captured using vertical nets through part of 1996 and 1997. Fourteen adult hares (nine females and five males) were tagged with radiocollars and located by triangulation on a daily basis at least once a week. Habitat use was estimated using a geographical information system. The average home range size was 28 ha for males and 24 ha for females. No significant differences were observed between sexes. Significant differences were observed in the use of scrub areas and in dry pastures. During the dry and wet seasons, males and females were most often located in the pastures of the ecotone, rush stands and scrub. The dense bracken (Pteridium aquilinum) and seaside bulrush (Scirpus maritimus) communities were avoided. These results are the first on the spatial ecology of this species in its native habitat.

Study on Key Technology in the Control Surveying of Jinan-Qingdao Highway’s South Line

The south line of Jinan Qingdao highway (which is short of Ji-Qing south line) spans 281km, whose geomorphy is mainly composed by mountain lands and hills. Approximately, it runs from east to west and straddles several projection zones. Systemic conformance of its layout and measurement, high precision in company with multifunctional planes and vertical control nets make up this project’s key technological problems. The report tells of the selection of central meridian in different areas of Ji-Qing south line and the layout, observation, adjustment, height fitting and precision statistics of GPS control network; the layout, observation, adjustment and precision counting of vertical control nets; Meanwhile, it analyses and discusses that how to guarantee the systemic conformance of coordinate system and vertical datum, together with eliminating the division of points’ coordinates and elevation values’ steps when primary survey design are being made synchronously in two super highways or in different areas of the same expressway.

Studies on the flight patterns of foraging sand flies

Phlebotomine sand flies transmit Leishmania parasites that cause leishmaniasis in humans. We report experimental results that improve our understanding of how foraging sand flies proceed over flat or sloping ground and how they negotiate vertical obstacles. Three rows of traps were suspended at different heights on a wire fence. Those just above ground level captured 87% of all flies, traps set at one meter captured 11% while only 2% of the flies were captured in traps set two meters above ground. When traps were deployed on a vertical support wall, the mean catch per trap was much higher than for traps suspended on the fence. Traps suspended just above ground level captured 57% of all flies, traps set at one meter above ground captured 27% of the flies and even traps set at two meters captured 16% of the flies. Although, most flies were still captured close to the ground, a higher percentage reached the second and third rows of traps. Sticky traps on a vertical wall produced similar results with significantly more flies alighting on the lower sections of the trap closest to the ground. On a vertical sand fly-proof net the overall dispersal of the flies was more like on a wall than in open space. Traps suspended just above ground level captured 49%, traps set at one meter above ground captured 36% and traps set at two meters captured 15% of the flies. Following spraying of the net with deltamethrin (1%), fewer sand flies were captured but the reduction was not statistically significant. Our conclusions are that being small and frail, sand flies tend to fly close to the ground probably in order to avoid being swept away by gusts of wind. When they encounter a vertical obstacle, they proceed upwards close to the obstacle with intermittent stops. Therefore, insecticide-sprayed walls or vertical nets should be effective for controlling sand flies approaching human habitation.

The possibility of influencing vortex atmospheric formations

Video filming is used to investigate the possibility of influencing the characteristics of free concentrated vortexes generated under laboratory conditions over a heated underlying surface. The method of influencing consists in arranging obstacles in the form of vertical nets of different geometries in the path of air vortex.

Three aphid vectors of faba bean (Vicia faba) viruses in northern New South Wales and occurrence ofAcyrthosiphon pisum-transmitted isolates ofSoybean dwarf virus

Aphid-transmitted virus diseases are a constraint on production of faba bean (Vicia faba) and other cool season grain legumes in northern New South Wales (NSW), Australia. A field study in 2004 identified potentially important aphid vectors of viruses that infect faba bean. Individual alatae were trapped on vertical nets in four field situations and placed immediately on bioassay plants (faba bean seedlings) to identify viruses transmitted in persistent and non-persistent manners. Viruses were identified by nine virus-specific tissue blot immunoassays (TBIAs). Out of a total of 447 individual alatae comprising 14 species, 10 individuals comprising three aphid species transmitted a virus: five Acyrthosiphon pisum (two that transmitted Bean leafroll virus, two Bean yellow mosaic virus, and one Soybean dwarf virus, SbDV), four Aphis craccivora (all Beet western yellows virus, BWYV), and one Myzus persicae (BWYV). No transmissions were detected for the other 11 aphid species, including the faba bean colonising species Acyrthosiphon kondoi, although virus-like symptoms were observed in some cases. None of the alatae transmitted Subterranean clover stunt virus, Alfalfa mosaic virus, Cucumber mosaic virus, Pea seed-borne mosaic virus, or Turnip mosaic virus. In separate tests in which acquisition fed apterae were used to inoculate faba bean, A. pisum was able to transmit four additional isolates of SbDV from chickpea or subterranean clover from Queensland, Tasmania, and NSW. The potential importance of A. pisum, A. craccivora, and M. persicae as vectors is discussed. Of these, A. pisum appears the most likely to cause crop losses in faba bean based on propensity as a vector, numbers trapped, efficient colonisation, and severity of virus isolates transmitted.

Relative abilities of different aphid species to act as vectors ofCarrot virus Y

The abilities of different aphid species to act as vectors of Carrot virus Y(CarVY) in carrots were studied. Their effectiveness at transmitting the virus from infected to healthy carrot plants was compared using 5–10 min acquisition access feeds. With species that colonise apiaceous hosts, the percentage transmission efficiencies found were Myzus persicae: 56; Dysaphis foeniculus: 19; Aphis spiraecola: 17; D. apiifolia: 13; Hyadaphis foeniculi: 7; Cavariella aegopodii: 4; and H. coriandri: 3. With non-colonising species, the respective transmission efficiencies were Lipaphis erysimi: 34; Hysteroneura setariae: 14; Brevicoryne brassicae: 12; Acyrthosiphon kondoi: 10; Sitobion miscanthi: 7; Rhopalosiphum maidis: 2; and R. padi: 0.5. When flying aphids were trapped on vertical nets near to a CarVY-infected carrot planting, 11 out of 101 H. foeniculi caught transmitted the virus to carrot seedlings but the 13 other aphids caught, which belonged to three non-colonising species, did not. If present in sufficient numbers, all 14 aphid species that transmitted the virus have the potential to be important CarVY vectors in carrot crops.

Lark Mirrors: From Tools to Folk Art

Skylarks have been a feature in British skies for longer then man can remember, and while their flight and song has inspired poets and artists, their flesh, grilled or in pies, whetted many an appetite. As they were sought for food, ways of catching them were devised and improved over time, until, approximately seventy years ago, they were finally afforded total protection. Before the advent of guns, nets were dragged and drawn over the fields at night so that roosting larks flew up and became entangled in them. In some places, larks were flushed towards vertical nets just before darkness fell. During the day, they were snared in horsehair nooses or they were lured to nets. When guns were devised, larks were shot, mostly as they were feeding in flocks. Shooting ‘into the brown’ was a common expression in circles. But sport shooting (shooting at individual larks) was also a popular pastime.