An improved and simplified trap for quantifying the distribution and supply of planktonic larvae to rocky shores

This paper describes a modified and improved plankton trap foruse on rocky shores. The trap is composed of a simple filteringdevice and collection bag which allows assessment of spatialand temporal variation of on-shore larval supply.     

Estimating oxygen consumption from body length for some chironomid larvae

Summary The relationship between oxygen consumption and body length was determined for eight larval chironomid species in Bear Lake, Utah-Idaho. Respiration was measured by the micro-Winkler method in 1-cc tuberculin syringes filled with lake water and lowered to lake bottom. A total of 144 measurements of O₂ consumption was made.Oxygen consumption for all individuals was related to body length by a power function. On a double log plot the relationship was a straight line and by least squares regression was Y = 2.26X–1.72, where Y is log₁₀ oxygen consumption (µliters/animal per hour) and X the log₁₀ body length (millimeters). Correlation coefficient (r) was 0.884.The measurements in the lake were taken over a naturally occurring range of oxygen concentration of 5 ppm, but deviations from regression were not associated with differences in concentration. Body length covered a range from 1.5 to 12.6 mm, and the species represented carnivores and herbivores as well as different-aged in-stars.For some chironomid larvae at least, body length seemed preferable to other body size measurements because of ease in determination and reasonable precision.

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Zusammenfassung Das Verhältnis zwischen dem Sauerstoffverbrauch und der Körpergrö\e wurde an 144 Chironomidenlarven von acht verschiedenen Arten im Bear-See an der Grenze von Utah and Idaho bestimmt. Die Atmung der Tiere konnte mittels der Micro-Winkler-Methode in 1 ccm gro\en Glasbehältern gemessen werden. Diese Behälter waren zuerst mit Seewasser gefülltt and dann zum Grund des Sees herabgelassen worden.Der Sauerstoffverbrauch der einzelnen Tiere zeigte im Verhältnis zu ihrer Körperlange einen gradlinigen Verlauf auf doppellogarithmischem Papier. Eine Regressionsanalyse mittels der Methode der kleinsten Quadrate ergab die Gleichung Y = 2,26 X-1,72, wobei Y den Logarithmus des Sauerstoffverbrauchs in Mikrolitern pro Stunde pro Tier, and X den Logarithmus der Körperlange in Millimetern darstellt. Der Korrelationskoeffizient dieser Analyse betrug 0,884.Die Sauerstoffkonzentration im See war nicht gleichmä\ig sondern variierte fiber eine Spanne von 5 Promill. Diese Variation beeinflu\te aber nicht die Standardabweichung von der Regressionslinie. Die Körperlänge der Larven erstreckte sich von 1,5 bis 12,6 Millimeter. Die Larven gehörten fleischfressenden und pflanzenfressenden Arten an and befanden sich in verschiedensten Alterstadien der Entwicklung.Die Messung der Körperlange erschien, zumindest für einige Chironomidenlarven, leichter and mit guter Genauigkeit bestimmbar zu sein, als dies mit anderen Körpermassen der Fall ist.

     

A comparison of desiccation tolerance among 12 species of chironomid larvae

Tolerance to desiccation was compared among 12 Japanese species of chironomid larvae under the condition of 60% in relative humidity at 25.5?°C. Three parameters were assessed: time to 50% survival (T ₅₀), water loss at 50% survival (WL₅₀) and water loss rate (WLR). T ₅₀, WL₅₀ and WLR were determined as measures of desiccation tolerance, dehydration tolerance, and dehydration resistance, respectively. T ₅₀ was 64.4–142 min for most species, except Propsilocerus akamusi (Tokunaga) which took 872 min. WL₅₀ was 60.6–82.4% for all species. WLR was only 0.0664% per minute for Pr. akamusi, while it was 0.629–1.50% for the other species. These results showed that Pr. akamusi had a high desiccation tolerance due to a high preventive ability of evaporation from body surface. T ₅₀ showed no significant relationships to WL₅₀ or WLR among the 12 species, while there was a significant positive relationship between WL₅₀ and WLR. These results suggest that chironomid species have a trade-off tendency that a species has a high tolerance – low resistance or a high resistance – low tolerance for dehydration.     

A comparison of trap type and height for capturing cerambycid beetles (Coleoptera)

Wood-boring beetles in the family Cerambycidae (Coleoptera) play important roles in many forest ecosystems. However, increasing numbers of invasive cerambycid species are transported to new countries by global commerce and threaten forest health in the United States and worldwide. Our goal was to identify effective detection tools for a broad array of cerambycid species by testing some known cerambycid attractants and a pheromone in different trap designs placed across a range of habitats. We compared numbers and species richness of cerambycid beetles captured with cross-vane panel traps and 12-unit Lindgren multiple-funnel traps, placed either at ground level (1.5 m high) or canopy level (approximately 3-10 m high), at eight sites classified as either residential, industrial, deciduous forest, or conifer forest. We captured 3,723 beetles representing 72 cerambycid species from 10 June to 15 July 2010. Species richness was highest for the subfamilies Cerambycinae and Lamiinae, which accounted for 33 and 46% of all species captured, respectively. Overall, the cross-vane panel traps captured approximately 1.5 times more beetles than funnel traps. Twenty-one species were captured exclusively in traps at one height, either in the canopy or at ground level. More species were captured in hardwood sites (59 species) where a greater diversity of host material was available than in conifer (34 species), residential (41 species), or industrial (49) sites. Low numbers of beetles (n < 5) were recorded for 28 of the beetle species. The number of species captured per week ranged from 49 species on 21 June to 37 species on 12 July. Cross-vane panel traps installed across a vertical gradient should maximize the number of cerambycid species captured.     

Seasonal migration by larvae of an epiphytic chironomid

1. A clear seasonal alternation of Endochiranomus albipennis larvae between submerged plants and the bottom sediment was observed in the littoral of a deep mesotrophic and a shallow eutrophic lake. The analysis of change in larval density and of occurrence of pupae suggests that larvae migrated from plants to the bottom sediment in early autumn and back to the plants, where they pupate, in spring. 2. Up to 95% of the third and fourth instar larvae overwintered in the bottom sediment in special cocoons. Larvae staying in the sediment without cocoons were also dormant. The timing of cocoon formation was different in the two lakes. 3. Migration may have a significant influence on the seasonal changes in dominance structure and density of epiphytic and benthic faunas.     

Design and effectiveness of a novel trap for capturing nesting songbirds

ABSTRACT Capturing songbirds at their nests can be challenging and time consuming. Although traps designed for capturing songbirds at their nests have been described in the literature, few are effective for capturing species with open‐cup nests. We describe a cylindrical trap designed to capture songbirds at nests up to 2 m above ground in grasses, forbs, shrubs, and small saplings. The nest trap is constructed using a rigid hoop, two pieces of mist net, three stakes, and twist ties. We used this trap to capture female Dickcissels (Spiza americana) and female Indigo Buntings (Passerina cyanea) at their nests, with success rates of 85% (N= 196) and 60–73% (N= 16), respectively. Trapping success was comparable to that using other passerine nest trap designs. Nest abandonment after trapping attempts was rare and similar to that reported in previous studies. Our nest trap is lightweight, easy to make, versatile enough to use in a variety of grassland and shrub habitats, and easily carried and deployed in the field.     

A light trap design for stratum-specific sampling of reef fish larvae

The vertical distribution of late stage reef fish larvae may potentially influence their dispersal, recruitment success and energetic expenditure during the recruitment process. To date, methods of examining the vertical distribution of reef fish larvae either under-sample late stage individuals, or are incapable of discretely sampling the water column. The aim of this study was to develop a light trap able to sample a narrow depth range enabling fine scale patterns of vertical distribution to be examined. The experimental traps radiated light in a relatively narrow beam with a maximum vertical angle of radiation of 7.5°, indicating that the traps could be placed 4.8 m apart and still sample discrete depth strata. Their catch efficiency was similar to conventional light traps, indicating that they are adequate sampling units. Preliminary data showed that most families are more abundant near the surface, although many have significant numbers of individuals lower in the water column. Some families (inc. Apogonidae) occurred in higher abundance at greater depths. Our experimental light traps permit increased resolution of the vertical distribution of late stage larval reef fishes in the field.     

Rates of ammonia release from sediments by chironomid larvae

SUMMARY. 1. Microcosms of Lake Balaton mud and sterilized sand and aerated water were used to evaluate ammonia increments in the overlying water as influenced by chironomid density and temperature. In the two approaches, the effects of sediment disturbance and metabolic excretion of chironomids were measured.
2. The activity of larvae increased the ammonia content of the overlying water at temperatures above 10°C. A rise of temperature to 20°C resulted in a 5–20-fold increase in ammonia release in both systems with chironomids.
3. At 10°C combined effects of sediment disturbance and of excretion produced lower release rates than did excretion rates alone (mud-water v. sand-water treatments). At higher temperatures (15 and 20°C) release rates of ammonia by sediment disturbance plus excretion were higher than excretion rates alone. Ammonia excretion contributed significantly to the total release at each temperature.
4. Metabolic mineralization of nitrogen compounds appears to be an important mechanism contributing to nitrogen regeneration from aerobic lake sediments. High N:P ratio (14:1) of chironomid excretion materials supports this interpretation.     

羽摇蚊幼虫和霍甫水丝蚓的生态毒理学研究

本文以羽摇蚊幼虫和霍甫水丝蚓为对象,进行了丁基磺毒杀作用的试验。结果表明,丁基磺不仅污染环境,而且对这两种水生生物均有较高的毒杀作用;这两种水生生物对其毒性都分别产生不同的症状;在低浓度下,亦产生不同效应;不同浓度丁基磺对摇蚊幼虫24小时毒理试验LC₅₀为256.2ppm,对水丝蚓LC₅₀为25.8ppm;不同季节出现的毒性效应均有差异。在试验结果的基础上,对水丝蚓中毒后出现了不同类型的症状;温度、酸碱度等不同生态因素对丁基磺毒性的影响以及加强水丝蚓生态毒理学工作的必要性等问题进行了讨论。     

A radioimmunoassay for chironomid hemoglobin

A double antibody, competitive radioimmunoassay was developed for the quantitation of stage-specific hemoglobin from the insect Chironomus thummi. The radioimmunoassay will detect as little as 150 picograms of Hb 3, a hemoglobin synthesized and secreted into the hemolymph of larvae during the 4th, but not the 3rd instar. The assay also detects cross-reacting hemoglobins purified from 4th instar larvae and in freshly laid eggs. Application of this radioimmunoassay is discussed in light of the cross-reacting Hbs in the insect.     

Habitat ecology of chironomid larvae of the Big Thicket streams

Chironomid larvae were collected from streams in the Big Thicket area of East Texas from November, 1981 to October, 1982. Primary stations were sampled monthly and secondary stations bi-annually. Samples of leaf debris, wood debris, and sand were taken from each station and the chironomid larvae occupying the substrates were analyzed.A total of 15 112 individuals including 87 species were collected. Four subfamilies of Chironomidae were represented: Tanypodinae (12 species), Diamesinae (2 species), Orthocladiinae (30 species), and Chironominae (43 species). The collections yielded a larger number of individuals and species than previous environmental studies in the Big Thicket. Twenty-two species are reported for the first time from Texas.The lowest number of individuals occupied the leaf debris with Rheotanytarsus sp. and Tanytarsus sp. 2 being dominant. The wood debris, probably the most stable of the substrates, contained the highest number of species with Tanytarsus sp. 2 being dominant. Most individuals occurred in the sandy bottom where Lopescladius sp. was dominant. Tanytarsus sp. 1 occurred in over 65 percent of the samples.The populations were generally higher during the autumn. This was probably a result of the life cycle and the effects of environmental factors. More younger instars occurred during the late summer and autumn. Also, water flow during the summer and autumn was low, providing a more stable environment, promoting chironomid population growth.     

Effect of preservation on wet weight biomass of chironomid larvae

Preservation of four species of chironomid larvae in either 10% formalin or 70% ethanol caused changes in the preserved wet weight expressed as a percentage of the original live wet weight. The magnitude of the change varied with species, preservative, preservation time and the nature of the water used for preservative dilution. Failure to take these factors into account can lead to errors in wet weight measurements as great as 47%. The use of io% formalin prepared with filtered habitat water appears to be the most suitable preservative for chironomid larvae.     

Habitat selection by chironomid larvae: fast growth requires fast food

1. Sediments have been considered as a habitat, a cover from predators and a source of food, but also as a source of potential toxic compounds. Therefore, the choice of a suitable substrate is essential for the development of chironomids. 2. For the midge Chironomus riparius (Meigen 1804) the growth rate of larvae has often been related to the food quality in sediments rather than to the amount of toxicants in the sediment. Both food quality and sediment-bound toxicants have been reported to determine the field distribution of chironomid larvae. 3. We therefore studied the habitat selection by C. riparius larvae of floodplain lake sediments, differing in both food quality and concentrations of sediment-bound toxicants. We offered the different sediments pairwise to the chironomid larvae in a choice experiment and their settlement in the paired sediments was determined after 10 days. 4. It was observed that larvae showed a clear preference for sediments with higher food quality, which also provided better growth conditions, and that the food quality overruled avoidance of the sediments with higher toxicant concentrations. 5. Our observations correspond with the persistence of this fast growing opportunistic chironomid species in organically enriched aquatic ecosystems independent of the contamination level.     

Dietary overlap and coexistence of chironomid larvae in a detritus-based stream

Hydrobiologia - Of the seven orders of macroinvertebrates that make up the DuffinCreek riffle community, the Chironomidae were the dominant taxonmaking up, numerically, 25.8–53.7% of the...     

Organic matter processing by chironomid larvae (Diptera: Chironomidae)

In laboratory experiments, we used fluorescent dye markers to investigate processing of organic matter by larvae of Psectrocladius limbatellus (Holm.) (Diptera: Chironomidae). 59% of the organic matter used was incorporated into tubes, 39% was present in faecal pellets (both after 24 h), and 2% was found in the larval gut at the end of experiments. Ingested matter passed through the gut rapidly, resulting in the gut being emptied more than 20 times each day. Further 24-h experiments using dye-marked faecal pellets showed that 6% of pellets produced were re-ingested and 12% were incorporated into tubes. There was no preference for conditioned faecal pellets as food over those that had recently been egested and tubes also provided a food reserve on which larvae feed. Chironomid larvae recycle organic matter resulting in its mineralization and their ‘engineering’ has a dramatic effect on the substratum. This revised version was published online in July 2006 with corrections to the Cover Date.     

Deformities in chironomid larvae as indicators of pollution (pesticide) stress

Chironomid larvae (Chironomus spp.,Dicrotendipes conjunctus andProcladius paludicola) collected from Cox Creek and Aldgate Creek, South Australia, showed morphological abnormalities similar to those reported in other studies elsewhere in the world. The sediment of Cox Creek contained high concentrations of pesticides and there was a significant correlation between the occurrence of mouthpart and antennal deformities in larvae and the concentration of DDT and the herbicide, Dacthal®.Laboratory experiments were conducted using a culture ofChironomus sp. to determine whether or not a causal relationship existed between exposure to pesticides and the occurrence of deformities in larvae. Results showed a positive relationship between the concentration of DDT and the percentage of deformed mouthparts (menta). The results for the effect of DDT on antennae and those for the effect of Dachthal® were less clear, but generally showed a higher incidence of deformity for treatments compared with controls.To compare these results to a natural population (i.e. from an unpolluted area) the incidence of deformities was measured for larvae collected from Deep Creek Conservation Park, an area virtually free of pollution. The significance of this work is discussed with regard to its wider application as a useful environmental monitoring technique for freshwater systems.     

The chironomid larvae of a small chalk stream in Berkshire, England

Abstract. 1. The longitudinal distributions of larval Chironomidae (Diptera) were examined for 1 year in the intermittent and perennial sections of the Winterbourne, a small chalk stream in Berkshire, England.
2. Forty-nine chironomid taxa were recorded at ten major sites which were sampled on six occasions and four additional taxa were recorded at sites sampled only once.
3. Cluster analyses using data from the major sampling sites identified three groups of sites. A pond in the stream channel which had a distinct chironomid fauna was distinguished from all other sites before the remaining intermittent sites were separated from all perennial sites on the basis of the chironomid fauna.
4. In the perennial stream, a site heavily shaded by trees had low species richness compared with partially and unshaded sites further downstream. The lowest site, which was near to the confluence with a larger chalk stream, the River Lambourn, had the highest number of taxa (thirty-five), including several which were frequent in the Lambourn.
5. By recording the occurrence of prepupae, an indication of emergence periods was obtained and many taxa were shown to have extended periods of emergence.     

Oxygen consumption and ammonia excretion of herbivorous chironomid larvae in Lake Balaton

The oxygen consumption and ammonia excretion of a herbivorous midge larva,Chironomus sp., inhabiting Lake Balaton was measured at two different temperatures. The loss of energy through respiration and that through ammonia excretion were calculated. The daily respiratory energy loss amounted to 655.5 ± 123.8 J g^–1 at 17 °C and to 1 160.0 ± 168.4 J g^–1 (dry weight) at 25 °C. Mean energy loss through ammonia excretion was about 40% less than through respiration.