Maximum Burrowing Depth Research Articles

Toxicity assessment of earthworm exposed to arsenate using oxidative stress and burrowing behavior responses and an integrated biomarker index

Arsenate (As-V) is a ubiquitous contaminant in soil as a result of excessive use of veterinary drugs and pesticides, causing enormous environmental risks. Multiple biomarkers have been used to assess the ecotoxicity of arsenic, however, the mechanisms of toxicity remain unclear. This paper describes the exposure of the earthworm (Eisenia fetida) to natural soil with different As-V concentrations for 28 days, then biomarkers from oxidative stress and burrowing behavior were quantified to evaluate As-V stress. Dynamic changes in reactive oxygen species (ROS), lipid peroxidation (MDA), adenosine triphosphate (ATP) content and antioxidant enzymes activity (Gpx, SOD, CAT) implied two stages of intensified stress responses and physiological adaptability. The transcriptional expression and regulation of antioxidant enzymes showed different responses. The mRNA expression of sod1 was up-regulated, while that of cat showed no significant change. The related regulators, nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), showed dose-dependent activation, suggesting antioxidant defense induced by Nrf2 signaling. The burrowing behavior after 14-day exposure indicated that As-V inhibited burrowing activity, especially the burrow length and maximum burrow depth. These multiple biomarkers were integrated using a biomarker response index (BRI) model, which showed significant dose-effect relationship especially on day 28, and suggested that ATP was a sensitive and representative biomarker. This study provided evidence that burrowing activity, Nrf2 and HO-1 were useful biomarkers warranting inclusion into the BRI model. Arsenic toxicity was comprehensively understood through redox homeostasis regulation, biochemical and behavioral changes, and these results suggested new strategies for soil pollutants diagnosis.

Strategies to control invasion of Sailfin Armoured Catfish, Pterygoplichthys spp. in wastewater-fed aquaculture bheries of East Kolkata Wetland, India with suggestion of a modified barrier based on the biological and behavioural characteristics

Sailfin armoured catfish ( Pterygoplichthys spp.), an alien invasive species of family Loricariidae has invaded extensively in wastewater-fed large aquaculture ponds (locally called ‘bheries’) of East Kolkata Wetlands (EKW), West Bengal, India. As there is no viable controlling method at present, commonly these fishes are removed by different physical methods and discarded. In the present study, we investigated the effectiveness and suitability of different in-practice Pterygoplichthys spp. control methods, based on on-field sampling, biological and behavioural study of the fish and also response analysis of the stakeholder’s of EKW. The results indicate that in-practice eradication efforts, like ‘repeated seine netting’ with or without removal of Eichhornia sheath of the pond periphery and ‘dewatering of pond’ aiming to reduce or eradicate Pterygoplichthys spp., are not fully effective, because of the capture avoidance ability and burrowing habit of these fishes. We found deep and branching burrows of Pterygoplichthys spp. in aquaculture ponds of EKW, with maximum burrow depth of 58 cm, and water in that burrows even after 12 days of dewatering. Hence, it is suggested stakeholders to keep dewatered pond exposed to sunlight for at least four weeks or above to ensure complete water-out from the burrows in which Pterygoplichthys spp. take shelter or lay their eggs. ‘Multilayer bamboo fencing’ or ‘combination of bamboo fencing and net barrier’ use by the stakeholders of EKW to prevent intrusion or re-intrusion of Pterygoplichthys spp. were found only partially effective, because of the capability of these fishes to damage net-blocking through their hard dorsal and pectoral spines or entry through the holes dug across the barrier in beneath or banks of the sewage intake channel. Based on learning on the biological and behavioural characteristics of Pterygoplichthys spp., we then suggested a modified version of barrier to the stakeholder’s of EKW, incorporating a sewage feeder pipeline, a concrete collection chamber with size separation arrangement made of hard materials like wire mesh and a dam of specific dimensions across the channel, for effective prevention of intrusion of these fishes in their aquaculture bheries.

Co-occurrence and potential resource partitioning between oligochaetes and chironomid larvae in a sediment depth gradient

Although detritivorous Tubificinae and chironomid larvae are important groups in functioning of both, fresh and brackish water ecosystem, their co-occurrence patterns in sediment is weakly known. We carried out two-year-long research in the brackish Vistula Lagoon (southern Baltic Sea), where both Tubificinae (Limnodrilus hoffmeisteri and Potamothrix hammoniensis) and larvae of Chironomus balatonicus occur in high densities. Because of different source of their food, we hypothesized that the ecological interactions between those two groups of detritivores are not antagonistic, thus allowing for their co-occurrence along the depth of sediment profile with lack of competition for space. Here we show that maximum burrowing depth, occasionally reaching 25 cm was significantly affected by the total density of the each group in the entire core. Tubificinae and C. balatonicus showed the highest density at 0–10 cm depth, where they co-occurred most frequently, with significant co-occurrence in the layers of 0–2 cm and 2–5 cm. We propose a hypothetical model of interactions between apparently the same functional groups and the complementary role they play in sediment reworking. It points to their coexistence in the shared microhabitat, but using space and food resources differently. Also, the consequences of their activity and habitat structuring are opposite—Chironomus larvae mostly affect the deeper layers of the sediments, while Oligochaeta both the deeper and surface layers. Thus, their requirements and ecological roles seem not to overlap, preventing competitive exclusion and allowing for co-occurrence.

Cadmium pollution alters earthworm activity and thus leaf-litter decomposition and soil properties

It has been reported that heavy metal contamination can affect litter decomposition and soil properties through its impact on microbial communities. However, it is still unclear whether the expected changes in earthworm activities in responses to heavy metal contamination could affect these properties. Therefore, we quantified earthworm (Eisenia fetida) responses in survival rate to lethal cadmium (Cd) concentrations (0, 50, 100, 150, 200, 250, and 300 mg L−1), and in burrowing ability, physiological characteristics, and feeding rate (on poplar leaf litter) to sub-lethal Cd concentrations (0, 15, 30, and 45 mg kg−1). Finally, sub-lethal influences of Cd on the decomposition rate of poplar leaf litter and on soil properties were investigated in the present of E. fetida. The 12-, 24-, 36-, and 48-h LC50 of Cd for E. fetida were 276.0, 208.6, 192.6, 179.8 mg L−1, respectively. With increasing Cd concentration, malondialdehyde was stimulated, superoxide dismutase first increased and then decreased, while feeding rate, total borrowing length, and maximum burrowing depth consistently decreased. Consequently, leaf-litter decomposition rate and soil nutrient concentrations generally decreased with increasing Cd concentration. Our results indicate that, by affecting earthworm activities, Cd inhibited leaf-litter decomposition and led to the degradation of soil fertility. This study highlights the importance of earthworms in mediating soil functions under heavy metal stress.

Variability in Particle Mixing Rates in Sediments with Polymetallic Nodules in the Equatorial Eastern Pacific as Determined from Measurements of Excess 210Pb

Radionuclide activities of 210Pb and 226Ra were measured to determine bioturbation coefficients (Db) in seven sediment cores from the Korean licensed block for polymetallic nodules in the Clarion–Clipperton Fracture Zone. Variability in Db is considered in the context of the sedimentological, geochemical, and geotechnical properties of the sediments. Db values in the studied cores were estimated using a steady-state diffusion model and varied over a wide range from 1.1 to 293 cm2/yr with corresponding mixing depths (L) of 26 to 144 cm. When excepting for spurious results obtained from cores where diffusive mixing does not apply, Db values range from 1.1 to 9.0 cm2/yr with corresponding mixing depths (L) of 26 to 63 cm. Such wide variability in Db and L values is exceptional in sites with water depths of ∼5000 m and is attributed in this study to an uneven distribution of sediment layers with different shear strengths and total organic carbon (TOC) contents, caused by erosion events. The studied cores can be grouped into two categories based on lithologic associations: layers with high maximum shear strength (MSS) and low TOC content, showing a narrow range of Db values (1.1–9.0 cm2/yr); and layers with low MSS and high TOC content, yielding much higher Db values of over 30 cm2/yr. The distribution of different lithologies, and the resultant spatial variability in MSS and labile organic matter content, controls the presence and maximum burrowing depth of infauna by affecting their mobility and the availability of food. This study provides a unique case showing that shear strength, which relates to the degree of sediment consolidation, might be an important factor in controlling rates of bioturbation and sediment mixing depths.

Using tsunami deposits to determine the maximum depth of benthic burrowing.

The maximum depth of sediment biomixing is directly related to the vertical extent of post-depositional environmental alteration in the sediment; consequently, it is important to determine the maximum burrowing depth. This study examined the maximum depth of bioturbation in a natural marine environment in Funakoshi Bay, northeastern Japan, using observations of bioturbation structures developed in an event layer (tsunami deposits of the 2011 Tohoku-Oki earthquake) and measurements of the radioactive cesium concentrations in this layer. The observations revealed that the depth of bioturbation (i.e., the thickness of the biomixing layer) ranged between 11 and 22 cm, and varied among the sampling sites. In contrast, the radioactive cesium concentrations showed that the processing of radioactive cesium in coastal environments may include other pathways in addition to bioturbation. The data also revealed the nature of the bioturbation by the heart urchin Echinocardium cordatum (Echinoidea: Loveniidae), which is one of the important ecosystem engineers in seafloor environments. The maximum burrowing depth of E. cordatum in Funakoshi Bay was 22 cm from the seafloor surface.

Earthworm (Eisenia fetida) behavioral and respiration responses to sublethal mercury concentrations in an artificial soil substrate

Mercury (Hg) is a highly toxic metal that has multiple natural and anthropogenic sources. Many studies have explored the effects of Hg on various physiological and biochemical processes in soil animals. However, the effects of Hg on earthworm behavior and respiration are unknown. In this study, earthworms (Eisenia fetida) were exposed to Hg-spiked artificial soils prepared to OECD specification. An avoidance test was performed using soils with 0, 1, 2, 4, 8, 16, 32, 64, and 128mgHg2+kg−1 dry soil,. The avoidance concentration of Hg to earthworms was 128mgkg−1, as determined according to ISO guidelines. Soils with 0, 2, 8, 32, and 128mgHg2+kg−1 dry soil were prepared to investigate the effects of Hg on the burrowing activity and respiration rate of earthworms. The cumulative burrow lengths of earthworms in 2D terraria were significantly shorter in soil containing Hg at concentrations of 8mgkg−1 or higher, compared with those in the control (no Hg). However, the maximum burrowing depth was significantly decreased only in soil containing the highest concentration of Hg (128mgkg−1). The respiration rates of earthworms were lower in all Hg treatments than in the control after 2 days and 7 days of exposure. This is the first report on the toxic effects of Hg on earthworm behavior and respiration. These results provide useful information for environmental monitoring and for assessment of Hg contamination in soils.

Antioxidant and behavior responses of earthworms after introduction to a simulated vermifilter environment

Vermifiltration is a new technology for treating wastewater with a high organic loading, but there is almost no published information on the biochemical and behavioral response of earthworms in a vermifilter environment. This study measured antioxidase enzyme (AOE) activities and reactive oxygen species (ROS) and malondialdehyde (MDA) levels in tissues of earthworms for a period of 56 d after transfer into simulated vermifilters. Three vermifilter media were tested. In general AOE activities, ROS and MDA were elevated for the first 3–5 d after transfer, variable for approximately the next 7 d, and statistically indistinguishable from controls after 15 d. Similarly, earthworm activity as measured by daily burrowing length was initially enhanced but converged with that of controls after 6 d. Removal of chemical oxygen demand (COD) from artificial wastewater was significantly correlated with AOE and ROS in earthworm tissues, and daily burrowing length of earthworms, but none of these parameters was correlated to NH4+-N removal rate, suggesting earthworms do not play a direct role in nitrogen removal in vermifilters. The data provide useful information for vermifilter operators about the biochemical adaptive process earthworms undergo when introduced to a vermifilter environment and the lag time between set up and reliable operation of a vermifilter. The results could potentially lead to development of preconditioning treatments to shorten the settling-down time for newly set up vermifilters. Maximum burrow depth was reduced in simulated vermifilters, suggesting an optimal depth for vermifilter substrates. The three vermifilter media tested differed in performance and possible reasons are briefly discussed.

Three-dimensional microdistribution ofChironomus balatonicuslarvae (Chironomidae, Diptera) in soft sediments from the Vistula Lagoon (South Baltic Sea)

Despite the worldwide distribution and ecological importance of Chironomus larvae in both freshwater and brackish water ecosystems, patterns of their spatial distribution have been rarely studied. This study was conducted in summer, spring and autumn (2010–2011) in the deep-water zone of the polymictic, strongly eutrophic Vistula Lagoon. Its objective was to test whether temporal changes in density of the larvae affect their horizontal microdistribution and burrowing depth. Horizontal distribution, as inferred from indices of dispersion and patchiness, was density-dependent. The larvae spread more regularly with increasing density. The decreased density was associated with an increase in clustered distribution. The larvae burrowed into sediments up to a depth of 25 cm. The maximum burrowing depth positively correlated with total density, but also depended on the size of the larvae. The smallest individuals (<10 mm) did not occur deeper than 5 cm. Larger larvae were encountered throughout the sediment profile. The largest larvae did not always burrow the deepest. In spring before pupation, the larvae gathered below the sediment surface.

Burrow morphology of Uca uruguayensis and Uca leptodactylus (Decapoda: Ocypodidae) from a subtropical mangrove forest in the western Atlantic

The continuous excavation of burrows by fiddler crabs generates bioturbation in the sediment, which can be estimated from burrow morphology. The aim of the present study was to describe the burrow morphology of Uca uruguayensis and U. leptodactylus and its relationship with demography of resident individuals and to estimate the level of bioturbation in the sediment generated by each species. For all individuals from each of the 2 species, sex was determined and the carapace width (CW; mm) measured. Burrows were characterized according to burrow diameter (BD; mm), maximum burrow depth (MBD; mm) and burrow volume (BV; cm(3) ). The density of each species in the study area was also evaluated. In both species, the males were larger and occupied burrows with higher BV compared to females. Differences between sexes in relation to the burrow characteristics might reflect sexual dimorphism within the group and are probably related to the fact that males use the burrows for mating. BD and BV showed significant positive relationships with the size of resident crabs. The amount of sediment removed per burrow was estimated from mean BV: 10.78 cm(3) of sediment/burrow for U. uruguayensis and 12.38 cm(3) of sediment/burrow for U. leptodactylus. Despite the density and depth differences between the 2 species, the similarity in burrow volume suggests that U. uruguayensis and U. leptodactylus present the same importance in terms of the bioturbation process. Burrow morphology is highly associated with characteristics of the occupant, although extrinsic factors should also be considered, and its description can provide estimates on the bioturbation generated by Uca species in mangrove forests.

Earthworm burrowing in laboratory microcosms as influenced by soil temperature and moisture

Earthworm burrows contribute to soil macroporosity and support diverse microbial communities. It is not well known how fluctuations in soil temperature and moisture affect the burrowing activities of earthworms. The objective of this experiment was to evaluate the maximum depth and length of burrows created by the endogeic earthworm Aporrectodea caliginosa (Savigny) and the anecic earthworm Lumbricus terrestris L. for a range of temperatures (5–20 °C) and soil water potentials (−5 and −11 kPa). The laboratory microcosm was a plexiglass chamber (45 cm high, 45 cm wide) containing 0.14 m 2 of pre-moistened soil and litter, designed to house a single earthworm for 7 days. Earthworm mass, surface casting and burrowing activities were affected significantly by soil temperature, moisture and the temperature×moisture interaction. Burrow length and maximum burrow depth increased with increasing temperature, but there was less burrowing in wetter soil (−5 kPa) than drier soil (−11 kPa). Weight gain and surface casting, however, were greater in soil at −5 kPa than −11 kPa. Our results suggest more intensive feeding and limited burrowing in wetter soil than drier soil. Earthworms inhabiting the non-compacted, drier soil may have pushed aside particles without ingesting them to create burrows. The result was that earthworms explored a larger volume of soil, deeper in the chamber, when the soil was drier. How these burrowing activities may affect the community structure and activity of soil microorganisms and microfauna in the drilosphere remains to be determined.

Effect of substrate composition on burrowing depth and respiratory current in two spatangoids (Echinoidea)

To investigate the influence of substrate composition on burrowing depth and respiratory funnel diameter, two species of irregular sea urchins (Spatangoida) were allowed to burrow in different substrates in laboratory experiments. The maximum burrowing depth and respiratory funnel diameters were measured. Both are dependent on substrate composition. In muddy sand the burrowing depth of Echinocardium flavescens (O. F. Müller 1776) increased as the proportion of mud in the sediment increased. The diameters of respiratory funnels were significantly smaller where the proportion of mud exceeded 50%. An exhalation current was visualized using a rhodamin solution. In Echinocardium flavescens and Brissopsis lyrifera, the exhalation current reaches the sediment surface posterior to the echinoid through a number (three to six) of small tubes.

STUDY ON THE CONDITIONS OF MAKING HABITATS OF SEEDING

This study examined the conditions in order to make most suitable habitats for hatchery-reared Japanese flounder. Flounder's critical velocity of bottom-clinging was estimated almost the same the swimming velocity under steady flow, which was about the four or six times of its total body length (TL). The value of the coefficient of flow tolerance took from 0.2 to 03, and the coefficient of mass force did about 1.0. On the basis of that result, the relationship between the thrust (Ft: dyn) and TL was closely resembled as Ft=15.2×TL2.73, and the wave conditions (Hmax: a maximum allowance wave Height) allowed to be suited for making habitats of flounder, a wave period (T: second), and the depth of liberation area (h: m) was described as Hmax=23.02T-1.36TL0.97h based on the theory of micro amplitude. Further more, the maximum burrowing depth observed the tendency of gradual decrease with its body length's increase. In this experiment, no population was observed washed away in spite of the hard drift sand conditions.

Burrow morphology of the echiuran wormMaxmuelleria lankesteri(Echiura: Bonelliidae), and a brief review of burrow structure and related ecology of the Echiura

The burrow morphology of the echiuran worm Maxmuelleria lankesteri (Herdman) was investigated in situ using a resin casting technique. Work was carried out in Lochs Sween and Creran on the west coast of Scotland in predominantly fine mud sediments. Burrow casts typically had only 1 opening, although there is evidence to suggest that a second opening may exist. In 58% of burrows, the opening, which was small and funnel-shaped, was associated with a surface mound reaching up to 20 cm in height. The tunnel below the burrow opening, the ‘neck’, was narrow and circular in transverse section with a smooth wall, possibly due to the action of the mucus-laden proboscis which emerges during feeding. The maximum burrow depth recorded was 80 cm and tunnel orientation became more horizontal with increasing depth. In some larger burrows, the tunnel began to orientate upwards towards its end. Below the neck, the tunnel was much wider but had a sub-circular transverse section. The burrows had distinct striations on the w...

Vertical open burrows in deep-sea sediments 2 m in length

Previous studies of the mixed layer, in deep-sea sediments suggest a maximum burrowing depth of about 10–30 cm (ref. 1). However, we now report that two recently obtained cores from the north-east Atlantic (S126/2 and S126/4) display open burrows to a depth of 214 cm within a distal pelagic turbidite. An organic lining in one of the burrows indicates a modern origin. Many of the burrows are less than 0.5 mm across and are only visible on fractured surfaces. Their effects on sediment mixing are probably minimal, but they provide a network of open vertical channels which considerably increases the permeability. This is of crucial importance to studies involving pore water movement, such as those associated with the radioactive waste disposal project. The effect of the burrows changes the calculated permeability from the equivalent of a clay to that of a coarse sand. The delicate structure of the burrows may result in their closure during handling, thus requiring their effect on pore water fluxes to be studied in situ.

Effects of burrowing by the fiddler crab, Uca pugnax (Smith)

Quantitative measurements were made of the burrowing activities of the fiddler crab ( Uca pugnax ). The rate of burrow appearance and disappearance, and average burrow volume and surface area, were measured in a set of quadrats. In a year, the population of crabs in the quadrats—42 crabs m −2 —can turn over approximately 18% of the upper 15 cm of sediment in a salt marsh (15 cm was the maximum burrow depth). Burrows increased the surface area by 59%. Burrowing may, therefore, significantly affect the composition and chemistry of salt marsh sediments.