Burrow Construction Research Articles

What is bioturbation? The need for a precise definition for fauna in aquatic sciences

The term 'bioturbation' is frequently used to describe how living organisms affect the substratum in which they live. A closer look at the aquatic science literature reveals, however, an inconsistent usage of the term with increasing perplexity in recent years. Faunal disturbance has often been referred to as particle reworking, while water movement (if considered) is re ferred to as bioirrigation in many cases. For consistency, we therefore propose that, for contemporary aquatic scientific disciplines, faunal bioturbation in aquatic environments includes all transport processes carried out by animals that directly or indirectly affect sediment matrices. These pro- cesses include both particle reworking and burrow ventilation. With this definition, bioturbation acts as an 'umbrella' term that covers all transport processes and their physical effects on the sub- stratum. Particle reworking occurs through burrow construction and maintenance, as well as ingestion and defecation, and causes biomixing of the substratum. Organic matter and microor- ganisms are thus displaced vertically and laterally within the sediment matrix. Particle reworking animals can be categorized as biodiffusors, upward conveyors, downward conveyors and regen- erators depending on their behaviour, life style and feeding type. Burrow ventilation occurs when animals flush their open- or blind-ended burrows with overlying water for respiratory and feeding purposes, and it causes advective or diffusive bioirrigation ex change of solutes between the sedi- ment pore water and the overlying water body. Many bioturbating species perform reworking and ventilation simultaneously. We also propose that the effects of bioturbation on other organisms and associated processes (e.g. microbial driven biogeochemical transformations) are considered within the conceptual framework of ecosystem engineering.

Male Burrow Digging in a Sex Role-Reversed Spider Inhabiting Water-Margin Environments

Allocosa brasiliensis is a sex role-reversed wolf spider that inhabits sandy water-margin environments. Males are larger than females and they dig deep burrows, whereas females construct shallow silk capsules. Females are the mobile sex that initiates courtship. Copulations occur inside male burrows and females prefer to copulate with males that construct deep burrows, suggesting high selective pressures acting on male digging behaviour. Our aim was to describe male digging behaviour and burrow architecture in A. brasiliensis. We recorded burrow construction of 10 males under laboratory conditions. Male burrows were vertical and tubular, with only one entrance, and in four cases showed a bowl-shaped chamber lateral to the bottom of the burrow. We distinguished eight behaviours associated with burrow construction. We found high frequencies of occurrence of sand extraction and high duration of silk deposition. Burrow characteristics are discussed in the light of the sexual strategies and habitat characteristics of the species.

Anti-predatory performance in hatchery-reared red tilefish ( Branchiostegus japonicus) and behavioral characteristics of two predators: Acoustic telemetry, video observation and predation trials

The anti-predatory performance of hatchery-reared red tilefish ( Branchiostegus japonicus) using tube-shaped burrows was studied together with the behavioral characteristics of potential predators, the white spotted conger ( Conger myriaster) and the marbled rockfish ( Sebastiscus marmoratus). White spotted conger were released in Maizuru Bay (Kyoto, Japan) and tracked using acoustic telemetry; they were also observed in a tank using video recording. White spotted conger tended to remain inside shelters, but occasionally swam outside briefly at night. Attacking behavior of predators and predation avoidance behavior of red tilefish were also recorded in a tank. Red tilefish construct tube-shaped burrows into which they retreat to avoid attack. White spotted conger wandered around the tank, often invading the burrows to prey on red tilefish. Predation by white spotted conger occurred at night. Inside the burrows, red tilefish were not easily caught and were able to escape through the other entrance of the tube-shaped burrow. Marbled rockfish, on the other hand, pounced on red tilefish immediately after prey recognition, ambushing their prey near the burrow entrance. Predation by marbled rockfish was frequently observed around dusk and dawn, but some red tilefish that remained inside burrows survived. White spotted conger is nocturnal and probably an olfactory predator, whilst marbled rockfish is crepuscular and an ambush predator. For stock enhancement of red tilefish, the construction of tube-shaped burrows and their diurnal behavior around the burrows are desirable characteristics in reducing predation by both white spotted conger and marbled rockfish.

Lizards cooperatively tunnel to construct a long-term home for family members.

Constructing a home to protect offspring while they mature is common in many vertebrate groups, but has not previously been reported in lizards. Here we provide the first example of a lizard that constructs a long-term home for family members, and a rare case of lizards behaving cooperatively. The great desert skink, Liopholis kintorei from Central Australia, constructs an elaborate multi-tunnelled burrow that can be continuously occupied for up to 7 years. Multiple generations participate in construction and maintenance of burrows. Parental assignments based on DNA analysis show that immature individuals within the same burrow were mostly full siblings, even when several age cohorts were present. Parents were always captured at burrows containing their offspring, and females were only detected breeding with the same male both within- and across seasons. Consequently, the individual investments made to construct or maintain a burrow system benefit their own offspring, or siblings, over several breeding seasons.

Evaluation of a Crayfish Burrowing Chamber Design With Simulated Groundwater Flow

Abstract Crayfish are a highly diverse group of freshwater crustaceans with great ecological and economic importance. Many species construct terrestrial burrows within which they reproduce, overwinter, and/or avoid desiccation. Basic life-history and environmental tolerance information is still lacking for many species, particularly in regards to terrestrial portion(s) of their life cycle. In this paper we present and evaluate a design for a crayfish burrowing chamber that allows for experimental control of burrowing conditions, including substrate, groundwater height and flow, as well as direct observation of burrow construction and measurement of groundwater quality. Results of evaluation assays with Cambarus striatus, a widespread secondary burrower native to the southeastern United States show that chambers are amenable to studies examining burrowing behavior, survivorship, growth and water quality. Water table height was easily manipulated in chambers. Seepage rates were strongly affected by substrat...

Mechanics and Energetics of Excavation by Burrowing Wolf Spiders,Geolycosaspp.

Burrowing wolf spiders, Geolycosa sp. (Araneae:Lycosidae), excavate vertical burrows and inhabit them throughout their lives or, in the case of males, until they mature and wander in search of mates. Three species: G. fatifera Kurata, G. missouriensis Banks, and G. rogersi Wallace were studied to understand how and at what expense the burrowing is accomplished. Normal and high-speed videography coupled with scanning electron microscopy revealed (a) that the convex surfaces of the two fangs, together, constitute the digging tool, (b) that boluses of soil are transported to the burrow entrance on the anterior surfaces of the chelicerae held there by the pedipalps, and (c) that each bolus is either incorporated into the growing turret or flung away, propelled by the forelegs. To elucidate the energetics of burrow construction, burrow volumes were calculated and then the costs associated with dislodging, elevating, and throwing the known volumes of soil were measured. A typical Geolycosa burrow, at a volume of 23.6 ± 2.0 ml and a depth of 13.2 ± 0.7 cm, required the removal of 918 boluses each weighing about 34 mg. The aggregate dislodging cost was close to 1.9 Joules in sand/sandy loam and 5.6 J in clayey subsoil, the work against gravity necessary to raise all of the boluses to the surface was about 0.13 J, and the aggregate cost of flinging the boluses was close to 0.014 J. Assuming that the ratio of external work to metabolic cost of external work is between 0.20 and 0.25 in spiders, the real cost of burrow construction would be between 8 J and 29 J, depending primarily on soil type. This is a small but not negligible cost when placed in the context of reproductive effort: a single Geolycosa egg, dozens to hundreds of which are produced in a clutch, contains about 10 J.

Bioturbating shrimp alter the structure and diversity of bacterial communities in coastal marine sediments

Bioturbation is a key process in coastal sediments, influencing microbially driven cycling of nutrients as well as the physical characteristics of the sediment. However, little is known about the distribution, diversity and function of the microbial communities that inhabit the burrows of infaunal macroorganisms. In this study, terminal-restriction fragment length polymorphism analysis was used to investigate variation in the structure of bacterial communities in sediment bioturbated by the burrowing shrimp Upogebia deltaura or Callianassa subterranea. Analyses of 229 sediment samples revealed significant differences between bacterial communities inhabiting shrimp burrows and those inhabiting ambient surface and subsurface sediments. Bacterial communities in burrows from both shrimp species were more similar to those in surface-ambient than subsurface-ambient sediment (R=0.258, P<0.001). The presence of shrimp was also associated with changes in bacterial community structure in surrounding surface sediment, when compared with sediments uninhabited by shrimp. Bacterial community structure varied with burrow depth, and also between individual burrows, suggesting that the shrimp's burrow construction, irrigation and maintenance behaviour affect the distribution of bacteria within shrimp burrows. Subsequent sequence analysis of bacterial 16S rRNA genes from surface sediments revealed differences in the relative abundance of bacterial taxa between shrimp-inhabited and uninhabited sediments; shrimp-inhabited sediment contained a higher proportion of proteobacterial sequences, including in particular a twofold increase in Gammaproteobacteria. Chao1 and ACE diversity estimates showed that taxon richness within surface bacterial communities in shrimp-inhabited sediment was at least threefold higher than that in uninhabited sediment. This study shows that bioturbation can result in significant structural and compositional changes in sediment bacterial communities, increasing bacterial diversity in surface sediments and resulting in distinct bacterial communities even at depth within the burrow. In an area of high macrofaunal abundance, this could lead to alterations in the microbial transformations of important nutrients at the sediment-water interface.

Terrestrial habitat use by the burrowing toad,Rhinella fernandezae(Anura: Bufonidae)

We studied the association between environmental variables and the terrestrial habitat use by adults of the burrowing toad Rhinella fernandezae in Buenos Aires, Argentina. We assessed the cover type, height of vegetation, soil moisture and hardness. We compared these habitat variables in quadrats where toads were present along a transect (n = 30 quadrats, 19 with toad burrows) with respect to randomly chosen quadrats (n = 17). We found that R. fernandezae does not use the habitat at random, and that habitat variables that mostly influenced its habitat use were soil hardness after raining, probably because it facilitates the construction of burrows, and broad-leaved plant cover, which may be affecting toads indirectly through other habitat variables, such as shadowing, air moisture and refuge from predators.

A comparison of epigean and subterranean locomotion in the domestic ferret ( Mustela putorius furo: Mustelidae: Carnivora)

Burrows are used by many mammals to escape predation, cache food and for parturition. Although the construction of burrows has been studied in some taxa, the locomotion while inside of them has received scant attention. In this study we collected simultaneous video and force data to characterize gaits, kinematics, peak ground reaction forces (GRFs) and external mechanical energy profiles in the domestic ferret, an animal that displays the typical morphology and behaviors associated with subterranean adaptations in mustelines. We compared kinematics and kinetics between locomotion in two experimental conditions: subterranean, simulated by a Plexiglass tunnel designed such that the ferrets’ peak back height was reduced by 40% and hip height by 25%, and epigean, or unconstrained overground. Despite the large change in posture, a striking number of gait and force variables were not statistically different between experimental conditions. In both subterranean and epigean conditions, the ferrets in our study traveled at similar average velocities (∼0.8 m s −1), preferred to use a lateral-sequence diagonal-couplet gait, and were more likely to demonstrate the in-phase fluctuations of external mechanical energy indicative of running mechanics (68% of all trials). The ferrets conformed to gait and mechanical patterns seen in a variety of other small (<1 kg) mammals rather than being unique, despite the divergent morphology of mustelines. Our results demonstrated biodynamically similar locomotion in both epigean and subterranean conditions and support the hypothesis that ferrets possess adaptations for tunnel locomotion.

Ethological study of African carpenter bees of the genus Xylocopa (Hymenoptera, Anthophoridae).

Over 200 bees of 4 African Xylocopa species were observed for 3 months on the island of Rubondo (L. Victoria, Tanzania). Some 40 burrows were investigated, 100 bees marked. Building techniques are minutely reported; burrow construction simplifies defence and allows re-use by succeeding generations. Food plants, collecting, provisioning and all aspects of ontogenesis are treated, insight given into pupal leg mobility and the much-debated emergence order after eclosion: the first-hatched bee, in the rearmost cell, prepares the way for siblings. Copulation and the copulatory hold are studied using tethered femalefemale, and illustrated. A few colonization experiments are described and s spectrogram of begging sounds given. Meeting of the generations, feeding of the young and nest-defence by young siblings throw light on the evolution of primitively eusocial communities. The known literature is reviewed in each chapter.

Are fiddler crabs potentially useful ecosystem engineers in mangrove wastewater wetlands?

The effect of different organic-rich sewage concentration (0%, 20% and 60% diluted in seawater) and absence or presence of mangrove trees on the survival, bioturbation activities and burrow morphology of fiddler crabs species was assessed. After 6months, males of both species always showed higher survival (∼80%) when compared to females (∼20%). Crabs inhabiting pristine conditions achieved higher survival (67–87%) than those living in sewage-exposed mesocosms (40–71%). At 60% sewage loading, fiddler crabs processed less sediment (34–46%) during feeding and excavated slightly more sediment (45–80%) than at pristine conditions. While percent volume of the burrow chambers increased (13–66%) at contaminated mesocosms for both vegetation conditions, burrows were shallower (∼33%) in bare cells loaded with sewage. The results show that fiddler crabs presented moderate mortality levels in these artificial mangrove wetlands, but mainly in sewage impacted cells. However, they still function as ecosystem engineers through bioturbation activities and burrow construction.

The burrowing crab Neohelice granulata affects the root strategies of the cordgrass Spartina densiflora in SW Atlantic salt marshes

Salt marshes are among the most productive systems of the world, with plant primary production limited by soil oxygen deficiency and nutrient availability. Nevertheless, root adaptations to anoxia and nutrient acquisition are different and often incompatible. The SW Atlantic salt marshes are characterized by high densities of the deep (up to 1 m) burrowing crab Neohelice granulata (Dana, 1851) that may change soil physical and chemical characteristics by burrow construction. In this work, we experimentally evaluated the hypothesis that crab burrowing can enhance soil oxygenation, causing changes in Spartina densiflora Brongniart below ground tissues from structures adapted to anoxia to systems adapted for nutrient acquisition. This response, in turn, would enhance plant productivity. Results from field observations show that oxygen availability is higher in zones with high burrow densities. As burrow densities increased, the plant root distribution changed from shallow (associated to low oxygen availability) to deeper and vertically homogeneous, with a positive correlation between burrow density and plant aboveground biomass. Experimental exclusion of crabs shows that they induce changes of root strategies from anoxia toleration to nutrient efficient acquisition, with increasing plant productivity. The invasive success that this plant shows in other parts of the world is likely to be due to their ability to tolerate harsh environmental conditions. Our results suggest that the morphological plasticity of S. densiflora is also important in their native zone given the characteristics of their specific habitat.

Evidence of Social Nesting in the Ceratina of Borneo (Hymenoptera: Apidae)

The bee tribe Ceratinini is important for understanding early stages in social evolution. Their extant sister tribe Allodapini contains no strictly solitary species, and while some Ceratinini are commonly regarded as solitary, little behavioural data exist to substantiate this. Studies on Asian congeners have shown recurrent sociality in temperate and subtropical ranges while behavioural data are lacking in tropical regions. Field work along the west coast of Borneo in Sarawak, Malaysia, has provided some insight into these tropical taxa. Here we describe the nesting biology and social behaviour of four taxonomically described yet behaviourally unclassified Ceratina species. These four species are from three subgenera, namely Ceratina (Ceratinidia) accusator Cockerell, C. (Ceratinidia) nigrolateralis Cockerell, C. (Neoceratina) dentipes Friese, C. (Pithitis) smaragdula Fabricius. Nests of all species were typically attended by an adult female while all species except C. accusator had a low frequency of multi-female nesting assemblages. The four tropical ceratinines described here and all other behaviourally classified species exhibit recurrent patterns of maternal care, maternal longevity, and nest protection. Prolonged parental care found across the genus and occasional transitions into sociality make Ceratina of future interest for the study of life history and social evolution. The evolution of eusociality is considered one of the major transitions in evolution (Maynard Smith and Szathamary, 1995). In solitary species, offspring disperse and reproduce independently whereas workers in eusocial societies remain at the natal nest and largely forego reproduction to aid the queen in rearing siblings. Socially polymorphic lineages, those containing both solitary and social species, retain the plasticity to allow intra-specific comparisons of solitary with social life. The key to understanding the transition to sociality requires a group of closely related taxa possessing broad social, taxonomic and geographic diversity. Bees provide numerous contrasts to offer insights into the origin of sociality with their range of solitary to social forms. The small carpenter bees Hymenoptera: Apidae (Xylocopinae: Ceratinini) are commonly regarded as solitary (Michener, 1974). All behaviourally classified species share a relatively simple life history. Females disperse from their natal nests and find appropriate nesting substrate. These twig-nesting bees excavate linear burrows in the cores of dead exposed pithy stems. Subsequent to burrow construction, females forage for pollen and nectar provisions that they form into a pollen mass on which they lay an egg. After provisioning and oviposition, brood cells are cappe dw ith a partition of wood pith, and the process is repeated in a serial manner along the linear nest chamber.

Effects of hypoxia on animal burrow construction and consequent effects on sediment redox profiles

We conducted a laboratory experiment to investigate the effects of mild hypoxia on the burrowing behavior of three marine species (the hard clam Mercenaria mercenaria, the polychaete worm Neanthes virens, and the amphipod Leptocheirus plumulosus) and consequent effects on sediment redox profiles. Animals were introduced into defaunated sediment and allowed to burrow for four months at mildly hypoxic (2 mg l − 1 ) and normoxic (7 mg l − 1 ) dissolved oxygen (DO) levels. Sediment redox profiles were measured 10 times during the course of the experiment. At the end of the experiment, the sediment was imaged using computer-aided tomography to quantify burrow volume and location. For the three species, burrow volume remained constant over DO treatments, but amphipod and clam burrows were shallower in hypoxic treatments compared with normoxic treatments. Redox profile discontinuity (RPD) depth was shallower in hypoxic treatments compared with normoxic treatments for experiments without animals, indicating that water column oxygen concentration alone influences diffusion of oxygen into the sediment. Worms, but neither clams nor amphipods, increased the RPD depth relative to no-animal controls in both hypoxic and normoxic treatments, but the effect was greater in normoxic conditions. These results suggest that although hypoxia can reduce burrowing depth, infauna can still increase the depth to which oxygen penetrates the sediment, but not to the same degree as they would under normoxic conditions.

Breeding behaviour of the platypus (Ornithorhynchus anatinus) in captivity

Breeding platypuses (Ornithorhynchus anatinus) in captivity had proved difficult until the last 10 years but with improvements in husbandry and a greater understanding of platypus biology there have been seven successes at two institutions since 1998. This study, using closed circuit video monitoring, took place between 2001 and 2007 at Taronga Zoo and covered three breeding successes with one female in 2002/03, 2004/05 and 2005/06. Results have revealed a consistency of behavioural patterns, which accurately predicted breeding events, mating, burrow construction, subsequent denning period and emergence of young. The female platypus had a receptive period of 4–6 days in the spring of each year, during which her behaviour changed from avoidance to initiating contact with the male. After mating she immediately commenced burrow preparation, ending with a 3–5-day intense period of collecting wet nesting material before retiring to the burrow to lay. The gestation period was estimated at 15–21 days and incubation at less than 12 days. A suckling period of 114–127 days followed, with the frequency of maternal burrow visits and length of stay decreasing as the juveniles grew. Juveniles emerged 133 ± 4 days after retirement. This study provides new and important information about breeding behaviour in this species and will contribute to future breeding success of platypus in captivity.

Burrow characteristics of the co-existing sibling species Mus booduga and Mus terricolor and the genetic basis of adaptation to hypoxic/hypercapnic stress.

BackgroundThe co-existing, sibling species Mus booduga and Mus terricolor show a difference in site-preference for burrows. The former build them in flat portion of the fields while the latter make burrows in earthen mounds raised for holding water in cultivated fields. In northern India which experiences great variation in climatic condition between summer and winter, M. booduga burrows have an average depth of 41 cm, as against 30 cm in southern India with less climatic fluctuation.M. terricolor burrows are about 20 cm deep everywhere. The three chromosomal species M. terricolor I, II and III have identical burrows, including location of the nest which is situated at the highest position. In contrast, in M. booduga burrows, the nest is at the lowest position.ResultsThe nest chamber of M. booduga is located at greater depth than the nest chamber of M. terricolor. Also, in the burrows of M. booduga the exchange of air takes place only from one side (top surface) in contrast to the burrows of M. terricolor where air exchange is through three sides. Hence, M. booduga lives in relatively more hypoxic and hypercapnic conditions than M. terricolor.We observed the fixation of alternative alleles in M. booduga and M. terricolor at Superoxide dismutase-1 (Sod-1), Transferrin (Trf) and Hemoglobin beta chain (Hbb) loci. All the three are directly or indirectly dependent on oxygen concentration for function. In addition to these, there are differences in burrow patterns and site-preference for burrows suggesting difference in probable adaptive strategy in these co-existing sibling species.ConclusionThe burrow structure and depth of nest of the chromosomal species M. terricolor I, II and III are same everywhere probably due to the recency of their evolutionary divergence. Moreover, there is lack of competition for the well-adapted 'microhabitats' since they are non-overlapping in distribution. However, the co-existing sibling species M. booduga and M. terricolor exhibit mutual "exclusion" of the 'microhabitats' for burrow construction. Thus, location, structure and depth of the burrows might have been the contributory factors for selection of alternative alleles at three loci Sod-1, Trf and Hbb, which reflect difference in probable adaptive strategy in M. booduga and M. terricolor.

Seagrass as the main food source of Neaxius acanthus (Thalassinidea: Strahlaxiidae), its burrow associates, and of Corallianassa coutierei (Thalassinidea: Callianassidae)

Burrows of the thalassinidean shrimps Neaxius acanthus and Corallianassa coutierei are striking aspects in tropical seagrass beds of the Spermonde Archipelago, Indonesia. Burrow construction, behaviour, burrow type and associated commensal community were investigated to clarify the ecological role and food requirements of these shrimps and their commensals. Gut content analysis and stable-isotope data were used to unravel the food sources and the trophic interactions among the commensal community. Individuals of Neaxius acanthus were caught on Bone Batang Island. In narrow aquaria filled with sediment they constructed burrows resembling those found in the field. During burrow construction and maintenance only little sediment was brought to the surface, most was sorted and compacted to create a distinct lining. Maintenance work by single shrimps typically took about 5 min, after which the shrimp walked up to the entrance and rested for a similar period of time. There were no differences in behaviour between day and night. Intrasexual encounters inside the burrow were characterised by a high level of aggression and all resulted in one participant being driven out of the burrow. Intersexual encounters led to coexistence with both animals taking turns in burrow maintenance and guarding the entrance. Offered seagrass leaves were pulled underground, cut into pieces and eventually integrated into the lining. Burrows of Corallianassa coutierei resembled a deep U-shape. Chambers branching off halfway down and at the deepest point contained seagrass fragments. All steep parts of the burrow were lined similar to burrows of N. acanthus. No commensals were found associated with Corallianassa coutierei. However, burrows of Neaxius acanthus in the field typically contained a pair of shrimps, up to 8 individuals of the commensal bivalve Barrimysia cumingii and large numbers of gammarid amphipods. Other animals found associated with the burrow were the goby Austrolethops wardi, a palaemonid shrimp species and two species of tube-building polychaetes, one of which was also found as an epibiont on N. acanthus. Stable-isotope and gut content analyses indicate that the diet of Neaxius acanthus, its commensal Austrolethops wardi, and Corallianassa coutierei is mainly derived from detrital seagrass leaves, with a potential contribution of sediment organic matter and seagrass epiphytes. In contrast the isotopic signature of Barrimysia cumingii suggests the presence of symbiotic sulphide metabolism bacteria. This study underlines that, besides their interactions with the surrounding ecosystem, thalassinid shrimp burrows play an important role as a sub-habitat with a unique associated fauna.

Effects of the polychaetes Arenicola marina and Nereis diversicolor on microbial pyrene mineralization

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 50:197-207 (2008) - DOI: https://doi.org/10.3354/ame01162 Effects of the polychaetes Arenicola marina and Nereis diversicolor on microbial pyrene mineralization Karen Timmermann1,4,*, Gary T. Banta2, Anders R. Johnsen3, Ole Andersen4 1Department of Marine Ecology, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, PO Box 358, 4000 Roskilde, Denmark 2Department of Environmental, Social and Spatial Change, Roskilde University, PO Box 260, 4000 Roskilde, Denmark 3Department of Geochemistry, Geological Survey of Denmark and Greenland, 1350 Copenhagen K, Denmark 4Department of Science, Systems and Models, Roskilde University, PO Box 260, 4000 Roskilde, Denmark *Email: kti@dmu.dk ABSTRACT: The effects of 2 polychaetes, Nereis diversicolor and Arenicola marina, on the microbial mineralization of the organic contaminant pyrene, a polycyclic aromatic hydrocarbon (PAH), were followed over 44 d. We also examined whether the effect of the polychaetes was caused by enhanced oxygen supply, altered pyrene bioavailability and/or a changed abundance or activity of pyrene-degrading bacteria. The presence of polychaetes enhanced microbial pyrene mineralization by 180 to 200% compared with defaunated sediment. Collectively, the replicates of the different treatments showed that mineralization rates were positively correlated with the amount of oxidized sediment, which comprised mainly the 3 mm surface layer and zones around burrows (burrow sediment). The biogenic sediment structures had similar mineralization potential and abundance of pyrene-degrading bacteria as surface sediments. Pyrene mineralization potential in bulk (reduced and presumably anoxic) sediment was significantly lower than for surface and burrow sediments. However, when the bulk sediments were oxidized, mineralization rates increased rapidly. Collectively, these data indicate that oxygen availability controlled pyrene mineralization in these experiments. On the other hand, the presence of the polychaetes significantly reduced the bioavailability of pyrene to the microbial degraders. Pyrene bioavailability in burrow sediment was always lower than the bioavailability in both surface and bulk sediments. In addition, N. diversicolor and especially A. marina decreased the bioavailability of pyrene in surface sediments compared with that of surface sediments in the non-bioturbated control. In conclusion, these polychaetes enhanced microbial pyrene mineralization significantly and this enhancement seemed to be caused by the increased oxygen supply due to burrow construction and irrigation. In contrast, these worms decreased pyrene bioavailability and, hence, counteracted to some extent the stimulating effect of irrigation. KEY WORDS: Oxygen · Bioavailability · PAH · Biogenic structures · Bioturbation · Mineralization potential · MPN Full text in pdf format PreviousCite this article as: Timmermann K, Banta GT, Johnsen AR, Andersen O (2008) Effects of the polychaetes Arenicola marina and Nereis diversicolor on microbial pyrene mineralization. Aquat Microb Ecol 50:197-207. https://doi.org/10.3354/ame01162 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 50, No. 2. Online publication date: January 31, 2008 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2008 Inter-Research.

Ecological Predictors of Range Areas and Use of Burrow Systems in the Diurnal Rodent, Octodon degus

AbstractVariation in animal space use patterns may be linked to numerous ecological factors affecting survival and reproduction. We examined the relationship between ecology and above‐ and below‐ground components of space use by Octodon degus, a semi‐fossorial rodent in Chile. We monitored the daytime minimum convex polygon and adaptive kernel range areas of 26 individuals and determined the number of burrow systems used by degus during night‐time radiotelemetry and trapping of burrow systems on two study grids at Rinconada de Maipú, a semi‐arid Matorral in central Chile. We quantified food biomass, soil hardness, distance to overhead vegetative cover, and density of burrow openings at putative nest burrows. Degus living on the grid with more shrub cover had larger range areas than degus living on the grid with less cover. The range areas of degus decreased with increasing distance from overhead vegetative cover. There was a weak (but statistically significant) negative relationship between the number of burrow systems used by degus and the distance to vegetative cover and density of burrow openings at burrow systems. Male and female degus had similar range areas. Our results suggest that overhead cover decreases the risk of predation to male and female degus. Degus probably balance the benefits of numerous burrow openings (reduced predation risk) with time and energy requirements of burrow construction and maintenance. Models of space use that consider the effect of multiple ecological variables should measure different dimensions of space use.

ACQUISITION OF SUBTERRANEAN HABITS IN TUCO-TUCOS (RODENTIA, CAVIOMORPHA, CTENOMYS): ROLE OF SOCIAL TRANSMISSION

Abstract A test was conducted to investigate if mother–infant social transmission plays a role in the acquisition of subterranean habits in the rodent Ctenomys talarum. Thirteen infants were reared by their mother in an experimental aboveground habitat that precluded burrow construction. At the age of natal dispersal, young were allowed to dig in the soil typically inhabited by the species. All experimental tuco-tucos engaged in burrowing activities after short latencies (51 s ± 35 SD). Aboveground excursions lasted a few seconds and covered short distances, and there were no significant differences between experimental and control wild tuco-tucos. The structure of the burrows constructed by experimental tuco-tucos did not substantially differ from those typical for the species. It is concluded that vertical social transmission is not essential for the development of subterranean habits in C. talarum. The results are discussed regarding growing evidence on social transmission and its alleged role during e...