Using Artificial Rocks to Restore Nonrenewable Shelter Sites in Human‐Degraded Systems: Colonization by Fauna

Many animals spend much of their time within retreat sites underneath loose surface rocks and may be highly selective in terms of the physical characteristics of the sites that they use. If such shelters are eliminated by anthropogenic activities, such as rock removal for landscaping, the only way to restore these nonrenewable habitats may be to replace them with artificial rocks. To construct artificial rock habitats, we need to understand which rock attributes are important for faunal use and develop methods to mimic these important natural retreat site characteristics. Based on our prior understanding of rocky retreat sites used by reptiles in sandstone outcrops of southeastern Australia, we constructed realistic‐looking artificial rocks from fiber‐reinforced cement and evaluated (1) the degree to which they mimicked natural retreat sites in both thermal regime and three‐dimensional crevice structure and (2) their colonization by fauna after deployment in the field. Our results demonstrate that thermal regimes and crevice structures beneath the artificial rocks were similar to those beneath natural rocks. In addition, 100% of the artificial rocks were colonized (by 45 invertebrate, six lizard, and two snake species, including the endangered Broad‐headed snake, Hoplocephalus bungaroides) after only 40 weeks. Together, these results suggest that restoring degraded habitats for rock‐dwelling species is feasible and can provide a rapid means of enhancing shelter‐site availability for such species.     

Phenology ofLemanea fucina (Rhodophyta) in a Rhode Island river,USA

In a fourth-order river in Rhode Island, USA, cover, frequency of occurrence, length and node number of the red algaLemanea fucina were greatest in July and August, at which time current velocity and water depth were minimum and temperature was maximum. Population abundance and plant size were lowest in fall-early winter. The length of reproductive region and carpospore frequency were also highest in June to August, whereas percent plants with open tips was least in July and highest in February. It appears that growth and reproduction are confined to a period from April to August, after which there is thallus deterioration and carpospore release; between September and March remnants of this population remain.Lemanea plants are epiphyte-free from September to January. Subsequently, they are colonized by caddisflies and then the red algaAudouinella violacea; by August, 100% of theLemanea plants are covered byAudouinella.     

A scanning electron microscope study of interactions between micro-organisms andGaeumannomyces graminis (Syn.Ophiobolus graminis) on wheat roots

Roots of wheat grown in unsterilized sand inoculated withGaeumannomyces graminis (Sacc.) von Arx and Olivier were examined by scanning electron microscopy. Healthy roots had a mucilaginous covering and were sparsely colonized by bacteria, but asG. graminis colonized the roots the mucilage disappeared and the numbers of bacteria on the surface increased. Lysis of the hyphae occurred, apparently caused by bacteria that colonized the hyphae. Inoculation of wheat in axenic culture with a strain ofPseudomonas fluorescens that was antagonistic toG. graminis in agar gave some protection against the pathogen; lysis of hyphae was observed where protection occurred.     

Survival of Macrophomina phaseoli (Maubl.) Ashby on cucurbit roots

Summary Experiments on the survival ofM. phaseoli on cucurbit root pieces were carried out. The sclerotia ofM. phaseoli were almost unaffected by 10 months dry storage in the laboratory. Under dry to moderately moist soil conditions it survived for 2 months with little loss of viability. In wet soils however, the buried root pieces were colonized by other soil microorganisms which prevented the growth ofM. phaseoli.     

Substrate characteristics affect colonization by the bloom-forming diatom <Emphasis Type="Italic">Didymosphenia geminata</Emphasis>

The long-stalked Didymosphenia is capable of forming large blooms and is expanding its range. To better understand the colonization dynamics of this species, we investigated the role of substrate characteristics—rock roughness and biofilm condition—on Didymosphenia colonization in a montane Colorado stream. Rocks differing in roughness (shale and sandstone) were treated to manipulate the diatom-dominated biofilm by scrubbing or submersion in 30% hydrogen peroxide. Initial chlorophyll concentration differed among rock types (sandstone > shale) and biofilm treatments (untreated > scrubbed > hydrogen peroxide-treated). Rocks were placed in a Didymosphenia bloom area for 8 days. More Didymosphenia colonized the rougher sandstone than the smoother shale, and more colonized stones with intact biofilms than stones with reduced biofilms (intact > scrubbed > hydrogen peroxide). These results suggest that rougher stones may be targeted for surveillance for new populations and that the colonization of intact biofilms is consistent with Didymosphenia’s habitat in regulated rivers, where biofilm-scouring spates may be suppressed.     

Interaction of Pseudomonas putida ATCC 12633 and Bacteriophage gh-1 in Berea Sandstone Rock

Measurements of the passage of Pseudomonas putida ATCC 12633 and a phage-resistant mutant through Berea sandstone rock were made. When bacteriophage gh-1 was adsorbed within the rock matrix, a reduction in the passage of the susceptible but not the resistant cells through the rock was observed.     

Thermal preferences and limits of Triatoma brasiliensis in its natural environment - Field observations while host searching

The goal of this work was to explore the thermal relationship between foraging Triatoma brasiliensis and its natural habitat during the hottest season in the state of Ceará, Brazil. The thermal profiles were determined using infrared analysis. Although the daily temperature of rock surfaces varied in a wide range, T. brasiliensis selected to walk through areas with temperatures between 31.7-40.5ºC. The temperature of T. brasiliensis body surface ranged from 32.8-34.4ºC, being higher in legs than the abdomen. A strong relationship was found between the temperature of the insect and the temperature of rock crevices where they were hidden (r: 0.96, p < 0.05). The species was active at full sunlight being a clear example of how the light-dark rhythm may be altered, even under predation risk. Our results strongly suggest a thermal borderline for T. brasiliensis foraging activity near 40ºC. The simultaneous determination of insect body and rock temperatures here presented are the only obtained in natural habitats for this or other triatomines.     

Occurrence of Aspergillus allahabadii on sandstone at Bayon temple,Angkor Thom,Cambodia

Microbial biofilms on surface of sandstone is detrimental to the integrity of the substratum material and they are biodeteriogens responsible for the damage of sandstone over time. We observed that fungi formed extensive biofilms on areas previously colonized by autotrophic and heterotrophic microbial biofilms causing darkening of the stone surface. Appearance of fungi on these biofilms has resulted in removal of the preformed biofilm through extensive examination of sandstone surfaces in Angkor Thom, Cambodia. One fungus, isolated from the surface with capability of removing biofilms, was purified and identified as Aspergillus allahabadii during our survey and sampling of microbial biofilms at Bayon temple, Angkor Thom, Cambodia in 2008. Ribosomal RNA (ITS and 5.8S) and β-tubulin gene sequences were phylogenetically analyzed to confirm the taxonomy of this strain. In addition, its protein profile and enzyme assays were also carried out and β-galactosidase was the highest among 7 enzymes tested. Our results suggest that fungi may have an important role in removing microbial biofilms on surfaces of stone and potential mechanisms and applications are discussed.     

Microbial flora associated with colonized and wild populations of the biting gnat Culicoides variipennis

Comparisons were made between the microbial flora in a natural breeding site and in the rearing medium of a laboratory colony and between microbial flora of wild and colonized flies of the biting gnat Culicoides variipennis. Members of the microbial flora at both the natural site and in the colony rearing medium were mostly common contaminants of polluted water; e.g., Enterobacter, Flavobacterium, and Pseudomonas. Anaerobic bacteria (Clostridium spp. & Bacteroides spp.) and the diatom Navicula were found at the natural breeding site, but were not found in the colony rearing medium. The microbial flora isolated from pupae and adults of both wild and colonized flies was similar to that in the natural breeding site and the colony rearing medium. There was no evidence of a specific association of any bacterial genus with either larvae, pupae, or adult flies in the laboratory colony.

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Zusammenfassung Die Gnitze Culicoides variipennis ist der Vektor des Virusagens der wirtschaftlich wichtigen und weit verbreiteten Blauzungenkrankheit von Rindern, Schafen und wilden Wiederkäuern. Für die Entwicklung einer Technik zur Krankheitsbekämpfung ist eine große Zahl von Mücken notwendig. Eine Bakterienmikroflora ist zur Zeit unentbehrlich für das Zuchtmedium, das zur Erzeugung der Mücken gebraucht wird. Aus diesem Grunde wurden Mikroorganismen, die mit verschiedenen Stadien der Mücken verbunden sind, identifiziert. Für die Mücken waren keine spezifischen Bakteriengenera erforderlich, was darauf hinweist, daß schon jedweder von verschiedenen Mikroorganismen eine günstige Nahrungsquelle für die Mücken darstellt. Diese Befunde erwiesen sich als vorteilhaft für die Laborzucht der Mücken, was wiederum für die Untersuchungen zur Bekämpfung und Ausrottung der Blauzungenkrankheit beim Viehsbestand von Nutzen ist.

     

Nest site selection by fire ant queens

Summary We examined nest site selection by foundresses of the polygyne form ofSolenopsis invicta. In the laboratory, foundresses were allowed to nest in control soil vs. soil inoculated with refuse from a colony ofPheidole dentata, a natural enemy. In a second experiment foundresses chose between control andS. invicta soil. More foundresses (100%) avoided the soil of a natural enemy than the soil of a conspecific colony (79%) that may accept them into the nest. Foundresses from this polygyne ant appear to avoid other colonies in general, but avoid heterospecific colonies more.     

Temporal variation in thermal plasticity in a free-ranging subalpine lizard

Thermally variable environments are particularly challenging for ectotherms as physiological functions are thermo-dependent. As a consequence, ectotherms in highly seasonal environments are predicted to have greater thermal plasticity. However, much of our understanding of thermal plasticity comes from controlled experiments in a laboratory setting. Relatively fewer studies investigate thermal plasticity in free-ranging animals living in their natural environment. We investigated the presence of thermal plasticity within a single activity season in adult males of a natural high elevation population of White's skink (Liopholis whitii) in south-eastern Australia. This species lives in a permanent home site (rock crevice and/or burrow), facilitating the repeated capture of the same individuals across the activity season. We monitored the thermal variation across the field site and over the activity season, and tested thermal tolerances and performance of male L. whitii on three occasions across their activity season. Maximum and average temperatures varied across the field site, and temperatures gradually increased across the study period. Evidence of temporal plasticity was identified in the critical thermal minimum and thermal tolerance breadth, but not in the critical thermal maximum. Thermal performance was also found to be plastic, but no temporal patterns were evident. Our temporal plasticity results are consistent which much of the previous literature, but this is one of the first studies to identify these patterns in a free-ranging population. In addition, our results indicate that performance may be more plastic than previous literature suggests. Overall, our study highlights the need to pair laboratory and field studies in order to understand thermal plasticity in an ecologically relevant context.     

Colonization of the root zone ofAmmophila arenaria by harmful soil organisms

The role of harmful soil organisms in the degeneration ofAmmophila arenaria at coastal foredunes was examined by the growing of seedlings ofA. arenaria in soil samples collected from its root zone. Three sites, each representing a successive stage in foredune succession were examined: (1) a highly mobile dune (sand accretion of 80 cm year⁻¹) with vigorousA. arenaria, colonizing only the upper 30-cm of the annually deposited layer of sand, (2) a mobile dune with vigorousA. arenaria (sand accretion of 22 cm year⁻¹) and a 1-metre soil profile completely colonized by roots and (3) a stable dune (no sand accretion) with degeneratedA. arenaria and young roots mainly present in the upper 0–10 cm. In the upper part of the highly mobile site, the presence of harmful soil organisms was confined to the root layers and at the mobile site for all depth layers a significant growth reduction ofA. arenaria was observed due to the activity of harmful soil organisms. At the stable site, however, growth had only been reduced in some of the depth layers. At all sites newly formed roots ofA. arenaria had been colonized by harmful soil organisms within one year. If present in sand prior to root growth harmful soil organisms reduced root length and root hair formation severely and they enhanced branching of the roots. It is concluded that harmful soil organisms initiate degeneration ofA. arenaria in stable dunes by attack of the root system, which makes the plants suffer from abiotic stress.     

Invasion of the Atlantic rock crab (Cancer irroratus) at high latitudes

With the increase in global oceanic trade the establishment of non-indigenous marine organisms has become a major environmental and economic problem worldwide. Recently, the Atlantic rock crab (Cancer irroratus) was reported in Icelandic waters, Eastern North Atlantic. This is the first record of this relatively large crab species outside its natural range, i.e. the east coast of North America. The crab was most likely transferred to Iceland as larvae in ballast water and has successfully established a reproducing population in Icelandic waters. The species is distributed along the southwestern- and western-coast of Iceland. Adult specimens are now common in Faxaflói Bay, Southwest Iceland, but with sporadic occurrences in western and northwestern Icelandic waters. The green crab (Carcinus maenas) and the spider crab (Hyas araneus) are the only native brachyuran decapod species commonly found in its new habitat, but despite its recent colonization the rock crab was the most abundant brachyuran in the areas studied in southwest Iceland. Egg bearing rock crab and green crab females were found from June to October, while egg bearing spider crab females were seen from July to December. In Southwest Iceland both rock crab and green crab larvae were abundant in mid-summer but rare in both spring and autumn, which is opposite of what was observed for the spider crab. The size and abundance of adult crabs, their reproductive conditions, and occurrence of all larval stages, indicate that the Atlantic rock crab has successfully colonized Iceland.     

Post-fire seedlings of Nothofagus alpina in Southern Chile show strong dominance of a single ectomycorrhizal fungus and a vertical shift in root architecture

We investigated belowground responses of Nothofagus alpina seedlings to post-fire conditions during natural regeneration after a wildfire in Chile, focusing on mycorrhizal community and root architecture. The complete root systems of 2-year-old N. alpina seedlings were extracted from a post-fire site with natural regeneration and compared to roots of seedlings from undisturbed forest nearby. Mycorrhizal morphotype richness was determined in each seedling. Morphometric parameters of tertiary root structure and dry biomass of whole root systems were determined in 5 cm vertical intervals and in four lateral root classes. With 43.5% of colonized vital mycorrhizal root tips, the Basidiomycete Descolea antarctica was the most abundant fungal symbiont on post-fire seedlings. Tertiary root morphology of these seedlings was distinct from control plants and characterized by a deep-reaching tap root with rather evenly distributed lateral branches whereas seedlings from the undisturbed site had shallower root systems with most lateral roots concentrated in the upper soil layers. Post-fire seedlings had more mycorrhizal rootlets and mycorrhiza-bearing third order lateral roots than control plants which was expressed in a 34% higher total root number but only a 10% higher total root biomass, although both values were not statistically significant. A major part of these fine roots in seedlings from burnt forest was found in deeper soil horizons, compared to the seedlings from undisturbed forest. According to our results, post-fire conditions clearly favour Descolea antarctica as an early ectomycorrhizal colonizer of Nothofagus seedlings at the studied site. As no significant changes in soil chemistry could be observed at the burnt site, the deep-reaching tertiary root architecture of these seedlings may be interpreted as a response to other abiotic factors like reduced moisture in surface soil.     

Biological interactions and their role in community structure in the rocky intertidal of Helgoland (German Bight,North Sea)

Over 3 successive seasonal cycles (April 1986 to October 1988), field experiments were established within 3 intertidal levels in the sheltered rocky intertidal of Helgoland (North Sea, German Bight). Competitors for space (Mytilus edulis, macroalgae), herbivores (Littorina spp.) and predators (Carcinus maenas) were either excluded from areas (0.25 m²) covered by undisturbed communities or enclosed at natural densities on areas that were cleared before of animals and plants. All the experimental fields (each 0.25 m²) were covered by cages with 4 mm gauze at the sides and a plexiglas top. The results of the experiments in the upper intertidal (occupied byLittorina spp. andEnteromorpha) showed that a natural density of herbivores could not prevent algal settlement and had only little influence on algal growth. Instead abiotic factors (storms, algae washed ashore) decreased the stock of the green algae. Experiments in the mid intertidal, dominated byMytilus (50% cover),Fucus spp. (20%) and grazingL. littorea (100 ind. m^?2) showed that community structure was directly changed both by grazing periwinkles and by competition for space between mussels and macroalgae. WheneverLittorina was excluded, the canopy ofFucus spp. increased continuously and reached total cover within two years. In addition to the increase ofFucus spp., the rock surface and the mussel shells were overgrown byUlva pseudocurvata, which covered the experimental fields during parts of the summer in the absence of herbivores. As soon as perennial species (fucoids) covered most of the experimental areas, the seasonal growth ofUlva decreased drastically. Presence and growth of macroalgae were also controlled by serious competition for space with mussels. EstablishedMytilus prevented the growth of all perennial and ephemeral algae on the rocks. However, the shells of the mussels provided free space for a new settlement ofFucus andUlva. In the lower intertidal (dominated by total algal cover ofF. serratus, herbivores such asL. littorea andL. mariae, and increasing number of predators such asCarcinus), the feeding activity of herbivores can neither prevent the settlement of the fucoid sporelings nor reduce the growth of macroalgae.F. serratus achieved a total canopy on the rock within one year. Doubled density of herbivores prevented the settlement ofFucus and most of the undercover algae. Predation byCarcinus onLittorina spp. had little influence on the herbivore community patterns. However, the crabs supported the establishment of macroalgae by excluding the mussels from the lower intertidal. In summary, the community organization and maintenance in the mid and lower intertidal is influenced to a high degree by biological interactions. Whereas both the relatively important herbivory byL. littorea and competition for space between mussels and macroalgae dominate in the mid intertidal, predation reaches its highest relative degree of importance for community structure in the lower intertidal.     

Patines et cortex de météorisation de grès du site rupestre d’Oum La Leg (Anti-Atlas, Maroc)

Within the framework of the European Commission's program “Patine du Desert” (DG Research; INCO-CT-FP6-2004-509100), partially concerning the preservation of Saharan engraved rock art, the approach led to the study of the sandstone patina from the rock art site of Oum La Leg (Anti-Atlas, Morocco). The rock and its Tazina school engravings are sometimes covered with a thin brown-ochre coating which only shows a dark patina, the desert patina. This film corresponds to a weathering cortex whose formation is contemporary with wet events from the Holocene period. On the surface, the patinas’ diversity is linked to the heterogeneous distribution of manganese oxides (birnessite and todorokite) due to a reorganisation which led to the incorporation of aeolian silts. Some dating suggestions are made to establish an ante quem age for the engraved lines.     

Arabidopsis thaliana model system reveals a continuum of responses to root endophyte colonization

We surveyed the non-mycorrhizal model plant Arabidopsis thaliana microscopically for its ability to form dark septate endophyte (DSE) symbioses in field, greenhouse, and laboratory studies. The laboratory studies were also used to estimate host growth responses to 34 Periconia macrospinosa and four Microdochium sp. isolates. Consistent with broad host range observed in previous experiments, field-, greenhouse-, and laboratory-grown A. thaliana were colonized by melanized inter- and intracellular hyphae and microsclerotia or chlamydospores indicative of DSE symbiosis. Host responses to colonization were variable and depended on the host ecotype. On average, two A. thaliana accessions (Col-0 and Cvi-0) responded negatively, whereas one (Kin-1) was unresponsive, a conclusion consistent with our previous analyses with forbs native to the field site where the fungi originate. Despite the average negative responses, examples of positive responses were also observed, a conclusion also congruent with earlier studies. Our results suggest that A. thaliana has potential as a model for more detailed dissection of the DSE symbiosis. Furthermore, our data suggest that host responses are controlled by variability in the host and endophyte genotypes.     

Weathering and Disintegration of Rocks At Oakwood Lake,South Dakota (39Bk7)

Abstract

Some cobbles and pebbles, enclosed in eolian sediment with artifacts, were unweathered and others were very highly weathered. Because the artifacts were tentatively dated as 1 ,000 to 2,000 years old, natural weathering of some of the igneous and metamorphic rocks into masses of loose mineral grains was unlikely. Fragments of igneous boulders, found and broken apart at the site, were heated in the laboratory to 300° C or 500° C and cooled rapidly in water through six cycles. Those fragments heated to 500° C disintegrated into individual mineral grains if fractured mechanically. At the Oakwood Lake site, 66% of the rock arranged into circular patterns appeared to be fire cracked but only 56% of the randomly placed rock had this characteristic. Use of the cobbles and pebbles as “pot boiler” in cooking probably has hastened the natural weathering rate.     

Effects of seven diets on the population dynamics of laboratory culturedTisbe holothuriae Humes (Copepoda,Harpacticoida)

The harpacticoid copepodTisbe holothuriae was collected from Saronicos Gulf (Greece) and reared under constant laboratory conditions. In order to study the effects of food on the population dynamics, seven diets were tested: the seaweedUlva; five artificial compound feeds: the liquid Fryfood^® (Waterlife), a powder ofMytilus, yeast, soya andSpirulina, respectively; and a mixed diet consisting ofUlva and Fryfood. The life cycle parameters (mortality, sex ratio, generation time, offspring production) were measured, and the demographic variables [mean generation time (T), net reproductive rate (Ro), and intrinsic rate of natural increase (r_m)] were determined. As to their efficiency regarding population dynamics, the diets ranked as follows: (1)Ulva+Fryfood, (2),Ulva, (3) Fryfood, (4)Mytilus, (5) soya, (6) yeast, and (7)Spirulina. In this order they cause a progressive increase of both larval mortality and generation time, a progressive decrease of sex ratio, number of offspring per egg sac, number of egg sacs per female and, consequently, of Ro and r_m. The observed differences between diets were most pronounced with respect to offspring production. Of the compound diets, those containing animal extracts were more efficient than those containing vegetable materials.Ulva plays an important role in the nutrition ofT. holothuriae, favouring offspring production as well as larval survival, development and pigmentation.Ulva in combination with Fryfood led to a greater copepodid survival and offspring production. This mixed diet proved to be the most favourable for rearing the Greek population oft. holothuriae, resulting in an efficient intrinsic rate of natural increase (r_m=0.304) of the population.