Capture Nets Research Articles

Description of Diplectrona aiensis Kobayashi, 1987 (Trichoptera: Hydropsychidae) larvae from Yata Hills, Nara Prefecture, Japan, with notes on habitat and ecology

We conducted a field survey and rearing experiment to investigate habitat, larval morphology, and ecology of Diplectrona aiensis Kobayashi, 1987. Larvae of this species look similar to those of D. takaii Nozaki, 2021, originally described as Diplectrona sp. DC by Akagi (1956); however, they can be distinguished by shape of the secondary setae on the head, thoracic nota, and abdominal segments. Our results revealed that generations of D. aiensis have overwintering and non-overwintering cohorts. Larvae build their retreat and capture nets on boulders and among leaf patches and prefer lower water velocity (mean: 22.2 cm/s, range: 1.3 ≦ 52.4 cm/s). Until the third instar, they feed only on detritus and after that, they feed on both animal and plant matter. This is the first study to report morphology, habitat, and ecology of D. aiensis.

Anecdotal Accounts of Manatee Behavior: Conservation and Management, Behavioral Ecology, and Cognition

Herein, we report anecdotes of manatee (family Trichechidae) behavior based upon accounts made by experienced observers. We have categorized the anecdotes into the broad categories of Conservation and Management (interactions with boats, people, and capture nets; rehabilitation and release), Behavioral Ecology (navigation, mother–calf interactions, interactions with conspecifics, mating behavior and birthing, anti-predator behavior, foraging and eating), and Cognition (sensory perception; learning, memory, and knowledge; interactions with objects, other species, and people; and mimetic behavior). These are all subjects that pertain to the goals of the Florida Manatee Recovery Plan of 2001. We found that many accounts report similar behaviors, suggesting that these may be fruitful lines of further inquiry. One subcategory, Navigation, appears to offer many research areas amenable to systematic study. The apparent behavioral flexibility and knowledge shown in manatee actions in several domains suggest that investigations of manatee intelligence are likely to be revealing.

Power-free colorimetric biosensing of foodborne bacteria in centrifugal tube

Early finding of pathogens is significant to avoid foodborne diseases. Here, a novel lab-in-centrifugal-tube colorimetric biosensor was reported for Salmonella typhimurium detection using immune nickel nanowires (NNWs) to form capture nets for specific bacterial separation, gold@platinum nanozymes (GPNs) to mark target bacteria for effective signal amplification, and a smartphone App to analyze color change for quantitative bacterial determination. A 3D-printed cylindrical magnetic separator with air pressure self-regulating structure and NNW capture nets was elaboratively constructed and assembled inside the disposable centrifuge tube to simply perform the bacterial separation, label, wash, coloration and detection. Under optimal conditions, Salmonella typhimurium could be quantitatively detected in 2 h with a low detection limit of 21 CFU/mL. The recovery of target bacteria in spiked pork samples ranged from 87.0% to 97.6% with the averaged recovery of 93.9%. This biosensor was Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free and Deliverable to end-users (ASSURED), and had shown the potential for point-of-care testing of foodborne pathogens to ensure food safety.

Lyapunov Optimal Touchless Electrostatic Detumbling of Space Debris in GEO Using a Surface Multisphere Model

High tumbling rates of uncooperative target pose strong technical challenges and collision risks that can prevent removal of the debris using contact, such as with robotic arms or capture nets. Electrostatic touchless detumbling is a promising technology that can be used to decrease the rotational velocity of an uncooperative object in geosynchronous orbit, from a safe distance. This paper demonstrates the advantages of applying a Lyapunov optimal control in conjunction with a surface multisphere model. This approach allows for the analysis of general shapes, eliminating the need for analytical approximations on debris shape and expected torque, employed by previous work. Moreover, using this model, the robustness of the system to uncertainties to the debris center of mass position is tested. This analysis uncovers an unstable phenomenon that was previously not captured using simpler models. An active disturbance rejection control ensures robustness of the system in the cases analyzed, also granting an increase in its effectiveness. It is shown in simulation that the system can exploit deviations in the center of mass to achieve a higher level of controllability and completely detumble all components of angular velocity.

Anaesthetic, clinical, morphometric, haematological, and serum chemistry evaluations of an Andean Cat Leopardus jacobita (Cornalia, 1865) (Mammalia: Carnivora: Felidae) before release in Bolivia

The Andean Cat Leopardus jacobita, one of the most rare and endangered feline species in the world, is distributed from central Peru to central Argentina. The aim of this study was to evaluate the health and morphometry of a subadult male Andean Cat that was rescued from wildlife trade in Bolivia and held captive for 165 days before being released back into its natural habitat. Physical immobilizations followed by anaesthesia using ketamine hydrochloride (KH) and xylazine hydrochloride (XH) were performed to obtain clinical, morphometric, haematological and serum chemical parameters. Physical immobilizations were efficient using capture nets. The combination of KH + XH had an average initial sedation effect within 12min with a range of 10–16 min after intramuscular application. Anaesthetic average plane lasted 41.7min with a range of 40–45 min and was extended to 64.5min (63–66 min range) with an addition of KH. The individual was underweight on arrival and gradually reached an ideal condition and was overweight before its release. Morphometry parameters showed that it grew during the captive period. It was released back into the wild when it was considered healthy. This is the first report of a protocol of physical and chemical immobilization, physiological values, and biometric variation of an Andean Cat under captive conditions.

Description of female genitalia, additional morphological variations, and courtship behavior and copulation of Macrostemum brasiliense (Fischer 1970) (Trichoptera: Hydropsychidae)

Macrostemum Kolenati 1859 is a cosmopolitan caddisfly genus with 105 described species easily recognized by the remarkable contrasting dark and clear wing patterns. The larvae of the genus build retreats with capture nets adapted to filter fine particulate organic matter. The genus has 19 described, Neotropical species, almost all described only by wing patterns and male genitalia. To date, only two Neotropical species have an associated immature stage and only one has the female genitalia described. Macrostemum brasiliense occurs in southeastern Brazil, primarily in the Atlantic Rainforest. The species has characteristic wing and body patterns, and phallic morphology recorded in literature and further described here. We contribute to knowledge of this species by further describing and illustrating the female genitalia, adding detail about wing variation patterns and venation, including the intriguing melanic female variation. This conspicuous Atlantic Rainforest caddisfly is now among the best-known species of Neotropical Trichoptera.

Influence of hand net mesh type and sex on experimental infection with Aeromonas hydrophila in Brazilian native fish Astyanax altiparanae

Farmed fish are permanently exposed to management procedures such as netting that can result in stress, skin injuries and subsequent secondary infections. The type of mesh material can modulate the magnitude of netting injury, yet there is scarce information on this topic for aquaculture species. The aim of this study was to evaluate the influence of net material on experimental infection by Aeromonas hydrophila using male and female Astyanax altiparanae, yellowtail tetra, as an infection model. Two hundred and fifty six A. altiparanae were distributed into 16 groups considering sex, types of net material (nylon, polypropylene, polyethylene, and a control group handled without net), and immersion challenge with A. hydrophila. Prior to infection, fish were anesthetized and submitted to netting for 30 s. Immediately, a fluorescein bath was applied under UV light to detect skin lesions. Later, fish were infected by immersion challenge in diluted bacterial solution, while control groups were immersed in sterile PBS. It was verified that the fish handled with nylon net mesh showed more extensive lesions than groups handled with polypropylene and polyethylene nets. Survival after infection was significantly lower in fish previously handled with nylon net when compared to all other groups, while no differences were found between polypropylene, polyethylene nets or fish handled by hand. There was no gender influence on lesions or mortality. It was concluded that yellowtail tetra is sensitive to netting and polypropylene and polyethylene capture nets should be used for handling this species. Additionally, nylon hand nets should be banned to avoid injuries that could serve as gateways for opportunist pathogens such as A. hydrophila

Calcified aquatic insect larval constructions in the Pleistocene tufa of Jebel El Mida, Gafsa, southern Tunisia: Recognition and paleoenvironmental significance

Calcified aquatic larval cases were recognized and identified in the Pleistocene tufa masses of Jebel El Mida, Gafsa, southern Tunisia. These larval constructions belong to three main insect families: caddisflies (Trichoptera, Hydropsychidae), midges (Diptera, Chironomidae) and aquatic moths (Lepidoptera, Pyralidae) that inhabited tubes in the tufa and spun nets. Each insect community has its distinctive characteristics of larval constructions that allow their recognition. The larval constructions recognized comprise fixed and portable (for caddisflies) dwelling cases and silken retreats and feeding capture nets. These last-mentioned are almost completely eroded and only remnants are preserved. The spatial distribution of these larval cases within the tufa is not random but, rather imposed by some specific paleohydraulic conditions. It's the reason why aquatic insect larval constructions are considered as prominent tool for the reconstruction of tufa and travertine depositional environments. Chironomid fixed dwelling cases (diameters range from 0.6 mm for clustered tubes to 3 mm) indicate the deposition of tufa under lotic (flowing) or lentic (standing) water conditions. The later hydraulic condition is shared with hydropsychids with fixed retreats (0.2–4 mm in diameter). Portable case-building caddisflies (case length ranging from 5 to 20 mm, and diameter from 3 to 5 mm at the cephalic end) prefer lentic conditions and are almost completely missing in high-energy flowing water locations that are preferred by pyralids (tubes are between 5 and 10 mm long and 3 mm in diameter). These insect families benefit from inhabiting the tufa by the availability of construction materials of their cases and the necessary space for their development.

Characterization of silk gland ribosomes from a bivoltine caddisfly, Stenopsyche marmorata: translational suppression of a silk protein in cold conditions

Larval Stenopsyche marmorata constructs food capture nets and fixed retreats underwater using self-produced proteinaceous silk fibers. In the Chikuma River (Nagano Prefecture, Japan) S. marmorata has a bivoltine life cycle; overwintering larvae grow slowly with reduced net spinning activity in winter. We recently reported constant transcript abundance of S. marmorata silk protein 1 (Smsp-1), a core S. marmorata silk fiber component, in all seasons, implying translational suppression in the silk gland during winter. Herein, we prepared and characterized silk gland ribosomes from seasonally collected S. marmorata larvae. Ribosomes from silk glands immediately frozen in liquid nitrogen (LN2) after dissection exhibited comparable translation elongation activity in spring, summer, and autumn. Conversely, silk glands obtained in winter did not contain active ribosomes and Smsp-1. Ribosomes from silk glands immersed in ice-cold physiological saline solution for approximately 4 h were translationally inactive, despite summer collection and Smsp-1 expression. The ribosomal inactivation occurs because of defects in the formation of 80S ribosomes, presumably due to splitting of 60S subunits containing 28S rRNA with central hidden break, in response to cold stress. These results suggest a novel-type ribosome-regulated translation control mechanism.

Molecular cloning, gene expression analysis, and recombinant protein expression of novel silk proteins from larvae of a retreat-maker caddisfly, Stenopsyche marmorata

Retreat-maker larvae of Stenopsyche marmorata, one of the major caddisfly species in Japan, produce silk threads and adhesives to build food capture nets and protective nests in water. Research on these underwater adhesive silk proteins potentially leads to the development of new functional biofiber materials. Recently, we identified four major S. marmorata silk proteins (Smsps), Smsp-1, Smsp-2, Smsp-3, and Smsp-4 from silk glands of S. marmorata larvae. In this study, we cloned full-length cDNAs of Smsp-2, Smsp-3, and Smsp-4 from the cDNA library of the S. marmorata silk glands to reveal the primary sequences of Smsps. Homology search results of the deduced amino acid sequences indicate that Smsp-2 and Smsp-4 are novel proteins. The Smsp-2 sequence [167 amino acids (aa)] has an array of GYD-rich repeat motifs and two (SX)4E motifs. The Smsp-4 sequence (132 aa) contains a number of GW-rich repeat motifs and three (SX)4E motifs. The Smsp-3 sequence (248 aa) exhibits high homology with fibroin light chain of other caddisflies. Gene expression analysis of Smsps by real-time PCR suggested that the gene expression of Smsp-1 and Smsp-3 was relatively stable throughout the year, whereas that of Smsp-2 and Smsp-4 varied seasonally. Furthermore, Smsps recombinant protein expression was successfully performed in Escherichia coli. The study provides new molecular insights into caddisfly aquatic silk and its potential for future applications.

The secretion process of liquid silk with nanopillar structures from Stenopsyche marmorata (Trichoptera: Stenopsychidae).

Stenopsyche marmorata larvae spin underwater adhesive silk for constructing nests and capture nets. The silk can be divided into fiber and adhesive regions, according to their function. The silk fiber region has a two-layer structure: a core layer situated at the center of the fiber and S. marmorata fibroin, the major component of the silk. In the anterior part of the anterior silk gland, the morphological characteristics suggest that the silk insolubilization leading to fibrillation occurs by luminal pH neutralization. The adhesive region is composed of three layers: the outermost (OM), B, and C layers. On the B layer, coated with the OM layer, numerous nano-order pillar structures (nanopillar structures) are located at regular intervals. A nanopillar structure is approximately 40 nm in diameter and 125 nm in length. The precursor materials of the nanopillar structure are electron-dense globules of approximately 25 nm in diameter that are located in the A layer of the lumen of the middle silk gland. The precursor globules autonomously connect to one another on the B layer when the liquid silk is transported to the lumen of the bulbous region. The nanopillar structures probably contribute to the strong underwater adhesion of S. marmorata silk.

Modification of net configurations of the Coda Netlauncher® to enhance bird capture

We modifi ed and evaluated capture nets fi red from the Coda Netlauncher® as a tool for capturing various avian species. We modifi ed the netlauncher by using customized nets to maximize the area of the capture zone. We captured 137 birds, comprising 12 species, in 23 attempts between July 2008 and October 2009 using this method. Capture success rates varied from 25 to 69% were comparable to success rates reported for other capture methods for these species. However, individual capture success for different net confi gurations varied greatly from 3 to 65%. Minimal injuries and 2 bird fatalities were reported. The netlauncher, using modifi ed nets, proved to be a cost-, labor-, and time-effi cient tool compared to what has been reported for other avian capture techniques. The netlauncher provides managers with a lightweight, fl exible method of capture that does not use combustive or explosive propellants, and, thereby minimizes associated training and regulatory oversight.

Silk Glands and Capture Nets of Hydropsyche kozhantschikovi Martynov (Trichoptera: Hydropsychidae) Larvae

Histological studies of the silk glands of the caddisfly larvae of Hydropsyche kozhantschikovi Martynov demonstrated that these structure fold twice into a ‘Z’ shape with the volume in the center comparatively thicker than in other sections. The glands are more slender towards the mouth and unite with the labium. A pair of muscles, an apodeum between the muscles and the body wall, and a tendon between the muscles and the glands were observed within the thorax. We assumed that silk is spewed through these structures. Examination of the material from the inside of the silk glands showed varying composition. The center was loose and heterogeneous, while the surrounding area was homogeneous. These differences were verified through immunohistochemistry. Scanning electron microscopy show that capture nets of H. kortizantschikovi larvae have randomly arranged silk strands.

Seston capture byHydropsyche siltalaiand the accuracy of capture efficiency estimates

Summary1. Suspension feeding by caseless caddisfly larvae (Trichoptera) constitutes a major pathway for energy flow, and strongly influences productivity, in streams and rivers.2. Consideration of the impact of these animals on lotic ecosystems has been strongly influenced by a single study investigating the efficiency of particle capture of nets built by one species of hydropsychid caddisfly.3. Using water sampling techniques at appropriate spatial scales, and taking greater consideration of local hydrodynamics than previously, we examined the size‐frequency distribution of particles captured by the nets ofHydropsyche siltalai. Our results confirm that capture nets are selective in terms of particle size, and in addition suggest that this selectivity is for particles likely to provide the most energy.4. By incorporating estimates of flow diversion around the nets of caseless caddisfly larvae, we show that capture efficiency (CE) is considerably higher than previously estimated, and conclude that more consideration of local hydrodynamics is needed to evaluate the efficiency of particle capture.5. We use our results to postulate a mechanistic explanation for a recent example of interspecific facilitation, whereby a reduction of near‐bed velocities seen in single species monocultures leads to increased capture rates and local depletion of seston within the region of reduced velocity.

Seasonal ‘fall out’ of sessile macro-fauna from submarine cliffs: quantification, causes and implications

Submarine cliffs are typically crowded with sessile organisms, most of which are ultimately exported downwards. Here we report a 24 month study of benthic fauna dropping from such cliffs at sites of differing cliff angle and flow rates at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The magnitude of ‘fall out’ material collected in capture nets was highly seasonal and composed of sessile and mobile elements. Sponges, ascidians, cnidarians, polychaetes, bryozoans and barnacles dominated the sessile forms. The remainder (mobile fauna) were scavengers and predators such as asteroid echinoderms, gastropod molluscs and malacostracan crustaceans. These were probably migrants targeting fallen sessile organisms. ‘Fall out’ material (including mobile forms) increased between May and August in both years. This increase in ‘fall out’ material was correlated with wrasse abundance at the cliffs (with a one month lag period). The activities of the wrasse on the cliffs (feeding, nest building and territory defence) were considered responsible for the majority of ‘fall out’ material, with natural mortality and the activity of other large mobile organisms (e.g. crustaceans) also being implicated. Current flow rate and cliff profile were important in amount of ‘fall out’ material collected. In low current situations export of fallen material was vertical, while both horizontal and vertical export was associated with moderate to high current environments. Higher ‘fall out’ was associated with overhanging than vertical cliff surfaces. The ‘fall out’ of marine organisms in low current situations is likely to provide an important source of nutrition in close proximity to the cliff, in an otherwise impoverished soft sediment habitat. However, in high current areas material will be exported some distance from the source, with final settlement again occurring in soft sediment habitats (as current speed decreases).

A new species ofSmicrideaMcLachlan (Trichoptera:Hydropsychidae) from Venezuela and its role in travertine biogenesis

We collected an undescribed hydropsychid caddisfly, Smicridea (Smicridea) travertinera, n. sp., from 2 sites in Venezuela. One of the sites, Quebrada El Charo, flowed over extensive calcareous formations of travertine, which were covered with retreats and capture nets of the new species. Smicridea travertinera was the most abundant aquatic insect colonizing travertine. We describe the adult male, the retreat and net, and gut contents. The retreat consisted of an aperture in the travertine with a capture net. Retreat-making behavior appears to cause both the biogenesis and erosion of the travertine formations.

Vertical stratification of bat communities in primary forests of Central Amazon, Brazil

The vertical stratification of bat communities in primary forests of the Central Amazon (80 km north of Manaus, Brazil) was investigated using capture nets in the canopy (17 to 30 m high) and in the understorey (from 0-2.5 m). Seventeen sites were sampled during one year (3398.5 mistnet-hours) and 936 individuals captured, belonging to 6 families, 29 genera and 51 species. Utilizing Non-Metric Multidimensional Scaling (NMMDS), a well-marked vertical stratification between the communities was verified, the canopy being the more utilized region. Fifteen species were exclusively captured in the canopy, 10 were predominantly captured in the canopy, and 12 species were exclus ively captured in ground nets. Species recorded and the communities they form were analysed using a matrix of guilds. The matrix obtained had 24 cells. A guild composed by background cluttered/gleaning frugivores was the richest in species (19), followed by background cluttered/gleaning insectivores (12 species). The results illustrate that when studying tropical forests it is highly desirable to involve both the lower and the upper part of the forests; otherwise the fauna would be merely subsampled, thus under-estimating the status and abundance of some species.

Anomalies on capture nets of Hydropsycheslossonae larvae (Trichoptera; Hydropsychidae), a potential indicator of chronic toxicity of malathion (organophosphate insecticide)

A laboratory study on the sublethal effects of malathion on the net-spinning behavior of the caddisfly larvae Hydropsyche slossonae was conducted in order to assess the potential of net anomalies as an indicator of chronic exposure to organophosphorus insecticides. Two anomalies were identified after chronic exposure to 0.01, 0.05, 0.1, 0.5 and 1.0 μg l −1 malathion. The first was a distortion of the midline meshes where the normal diamond shape structure was disrupted and the meshes were separated by extra strands (called ‘midline’ anomaly). The second aberration observed was a significant decrease in net symmetry. Both anomalies were highly correlated to the toxic action of malathion, i.e. inhibition of the acetylcholinesterase enzyme (AChE). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of capture nets did not show any modification of silk polypeptides after exposure to malathion, indicating that net distortions were not related to silk composition. Both anomalies seem to represent the symptoms of the specific toxic action of malathion; nevertheless, they can serve as an index of the physiological condition of the larvae, especially the midline anomaly. The symmetry of the nets decreased significantly after exposure to 0.5 and 1.0 μg l −1. However, the toxicity curves (EC 50) showed that the sensitivity threshold for the midline anomaly ranged from 0.11 to 0.28 μg l −1, which reflect more realistic exposure to concentrations expected to occur in the field. Hence, the use of capture net anomalies of hydropsychid larvae could represent a valuable indicator of sublethal toxicity induced by malathion and other organophosphorus insecticides in running waters.

Anomalies on capture nets of Hydropsyche slossonae larvae (Trichoptera; Hydropsychidae) following a sublethal chronic exposure to cadmium

A laboratory study on the sublethal effects of cadmium (Cd) on the net-spinning process of the larvae of Hydropsyche slossonae was conducted in order to assess the potential of net anomalies as an indicator of chronic exposure to Cd. Two major anomalies with different frequency levels were identified after chronic exposure to 0.37, 1.2, 11.6, 21.4 and 43.3 μg l −1 of Cd. The first was a distortion of the midline meshes where the diamond-shape structure is disrupted and the meshes are separated by extra strands (called ‘midline’ anomaly). The second aberration consisted of a distortion of the rectilinear structure of net opening by strands being fused or added over the meshes (called ‘crossover’ anomaly). The midline distortion may be linked to a physiological stress caused by Cd, which can affect the control of the net-spinning process. It was not possible to relate the crossover aberrations to a specific toxic action of Cd, but data indicated that both anomalies are independent from each other and that two modes of action could be implicated. Protein analyses of capture nets have revealed silk polypeptide modifications at the highest Cd concentration tested, indicating a possible effect of Cd interaction with silk proteins. However, neither a gradient-concentration nor a time-dependent response could be established with both aberration frequencies. Silk protein modifications would rather play a secondary role in the appearance of both net anomalies, and mostly at a high concentration level. Finally, the toxicity curves (EC 50) show that the sensitivity threshold for both types of aberration ranged from 1 to 5 μg l −1 which is highly sensitive compared with other sublethal effects of Cd on other macroinvertebrate species. Hence, the use of capture-net anomalies of hydropsychid larvae would represent a valuable indicator of sublethal toxicity induced by Cd and possibly by other metals in running waters.

Evolution of Net-Spinning Caddisflies: A Hypothetical Mechanism for the Reproductive Isolation of Conspecific Competitors

Net-spinning caddisflies construct capture nets with a wide range of mesh sizes, although the ancestral net-spinner presumably spun large-meshed nets while inhabiting high current velocity microhabitats. Thorp proposed that the evolutionary diversification of mesh sizes resulted from the competitive displacement of some net-spinners into lower flow microhabitats where less water and therefore less food passed through their nets. As a result, smaller meshes were selectively advantageous because they captured smaller, more abundant food items. Although competition is often strongest between conspecifics, Thorp did not present a mechanism by which reproductive isolation, and ultimately speciation, would be achieved between the competitively inferior and superior individuals. One such mechanism may have been temporal isolation. Because the initially large-meshed nets of the competitively inferior caddisflies would have been inefficient in the lower flow microhabitats, these individuals would have theoretically grown slower and emerged as adults later than the competitively superior individuals, which in turn would have led to reduced gene flow between the two populations. Although temporal isolation may not have been their final reproductive isolating mechanism, it may have opened the door to the evolution of other isolating mechanisms.