Niche segregation in sandy beach animals: an analysis with surface-active peracarid crustaceans on the Atlantic coast of Spain

Several species of sandy beach invertebrates regularly switch between burial in the sand during the day and surface activity at night to feed on stranded organic matter. Because all species consume essentially the same type of food (i.e., wrack) deposited over a restricted area, the potential for competition exists. Conversely, spatial and temporal segregation of surface activity behaviour is predicted to allow for niche separation. Here, we tested whether such behavioural niche separation occurs in three species of sympatric crustaceans (the talitrid amphipods Talitrus saltator (Montagu 1808) and Talorchestia brito Stebbing 1891, and the oniscoidean isopod Tylos europaeus Arcangeli 1938). We also assessed whether surface activity is modulated by weather, sea conditions and moon phases. Surface activity was measured over three consecutive moon phases on an exposed beach on the Atlantic Coast of Spain using pitfall traps along three transects from the foredunes to the swash. Adults of the amphipod T. saltator and the isopod T. europaeus overlapped spatially and temporally in their surface activity for most of the night. By contrast, the activity of T. brito was strongly disjunct in time and concentrated into significantly shorter bouts around dawn or dusk. Niche differentiation was also evident along the space axis, where T. brito occurred distinctly lower on the beach. Although several environmental factors (e.g., air and sand temperature, humidity, atmospheric pressure, wind speed and wind direction) were correlated with surface activity, this was highly variable amongst species, life stages, and synodic phases, and did not obscure the fundamental mosaic of spatio-temporal heterogeneity amongst species. Nocturnal feeding on beach wrack creates the potential for competition amongst sympatric crustaceans which can, however, be mitigated by behaviour patterns that separate consumers in time and space.     

Parasitism as a determinant of community structure on intertidal flats

The burrowing and movement ability of the New Zealand cockle Austrovenus stutchburyi is reduced when infected by echinostome trematodes. Previous experimental evidence from a single site suggests that this parasite-induced behavioural change of a key bivalve can affect the structure of the surrounding benthic community. By using multiple regression analyses on data collected from 17 intertidal flats, we here show that cockle parasitism is associated with macrozoobenthic community structure on a larger spatial scale. Regressions were performed for animal abundance, biomass, species diversity and species richness separately, entering cockle parasitism (infection intensity), presence/absence of ghost shrimps (Callianassa filholi), cockle density, primary producer abundance and organic content, particle size, sorting coefficient and gravel content of the substrate as predictors. Next to ghost shrimps, cockle parasitism was the best predictor of animal abundance by affecting (mainly positively) 8 of the 49 most widespread species significantly. Cockle parasitism was also associated with the biomass of anthozoans (positively), nemerteans (negatively) and bivalves (positively), whereas overall animal biomass was positively related to the sorting coefficient of the substrate. Species diversity was positively associated with cockle parasitism and gravel content of the substrate. Species richness was significantly associated with cockle parasitism (positively), ghost shrimps (negatively) and abundance of primary producers (positively) in combination. The impact of cockle parasitism on benthic community structure is believed governed directly or indirectly by (1) reduced sediment disturbance, (2) increased surface structural complexity and (3) availability of larval trematodes as an additional food source.     

Exaggerated orientation scatter of nocturnal passerine migrants close to breeding grounds: comparisons between seasons and latitudes

Using tracking radars, we investigated the variability of flight directions of long-distance nocturnal passerine migrants across seasons (spring versus autumn migration) and sites at the southern (56° N) and northern (68° N) ends of the Scandinavian Peninsula (Lund versus Abisko). Whilst most migrants at Lund are on passage to and from breeding sites in Fennoscandia, the majority of the migrants at Abisko are close to their breeding sites, and migration at Abisko thus to a large degree reflects initial departure from breeding sites (autumn) or final approach to breeding destinations (spring). The radar data were used to test predictions about differences in orientation and wind drift effects between adult and juvenile birds (a large proportion of autumn migrants consists of juvenile birds on their first journey), between situations far away from or near the goals and between different phases of migration (initial departure, en route passage, final approach to goal). The concentrations (both total and within-night concentrations) of flight directions differed significantly between seasons as well as sites, with the highest concentration at Lund in spring (mean vector length of track directions, r = 0.79) and lowest at Abisko during spring (r = 0.35). Partial wind drift and partial compensation were recorded at Lund, with a similar effect size in spring and autumn, whilst possible wind drift effects at Abisko were obscured by the large directional scatter at this site. The results from Lund support the prediction that the high proportion of juveniles in autumn contributes to increase the directional scatter during this season, whilst there was no support for predictions of differential wind drift effects between seasons and situations with different goal distances. The most striking and surprising result was the exceedingly large scatter of flight directions at Abisko, particularly in spring. We suggest that such an exaggerated scatter may be associated with final approach orientation, where migrants reach their specific goals from all various directions by final navigation within a more wide-ranging goal region. The larger scatter of autumn flight directions at Abisko compared to Lund may be due to exploratory flights in variable directions being more common at initial departure from breeding sites than later during migratory passage. These surprising results highlight the importance of studying and analysing orientation during final approach to (and initial departure from) migratory goals for understanding the orientation systems of migratory birds.     

An oligarchy of nest-site scouts triggers a honeybee swarm’s departure from the hive

Animals that travel in groups must synchronize the timing of their departures to assure cohesion of the group. While most activities in large colonies of social insects have decentralized control, certain activities (e.g., colony migration) can have centralized control, with only a special subset of well-informed individuals making a decision that affects the entire colony. We recently discovered that a small minority of individuals in a honeybee colony—an oligarchy—decides when to trigger the departure of a swarm from its hive. The departure process begins with some bees producing the worker-piping signal (the primer for departure) and is followed by these bees producing the buzz-run signal (the releaser for departure). In this study, we determined the identity of these signalers. We found that a swarm’s nest-site scouts search for potential nest cavities prior to the departure of the swarm from its hive. Furthermore, we found that the predeparture nest-site scouts are the sole producers of the worker-piping signal and that they are the first producers of the buzz-run signal. The control of the departure of a honeybee swarm from its hive shows how a small minority of well-informed individuals in a large social insect colony can make important decisions about when a colony should take action.     

Grassy field margins as potential corridors for butterflies in agricultural landscapes: A simulation study

Over the last decades, agricultural intensification has caused a dramatic reduction of grassy habitats. This habitat loss has had a strong negative effect on many meadow-living insect populations, including butterflies. As a part of the cross-compliance measures of the Common Agricultural Policy of the European Union, subsidies for creation and maintenance of grassy field margins (GFM) have been launched. Among other environmental issues, they may serve as corridors for movement of various meadow-living species between individual meadows. Their role as corridors has, however, not yet been demonstrated at the landscape scale and their characteristics that most significantly increase landscape connectivity are unknown. Empirical data for such studies are missing, as the GFM subsidies were launched only 3 years ago. One possibility to get some predictions of their outcomes is provided by simulation models. Here we present our simulation results, using an extension of the model developed by Kindlmann et al. (2004) for the Meadow Brown butterfly, Maniola jurtina. The extension includes the probability to cross a boundary (Conradt and Roper, 2006) that negatively influences dispersal rates but increases sensitivity to the corridor effect. Our simulations show that GFMs increase the dispersal rates between habitat patches and we predict the optimal combinations of width and number of GFMs in the landscape. This way we provide a decision-making tool for increasing landscape connectivity for M. jurtina and similar species. Although our simulations are based on a particular species, they may be generalized because this species shows dispersal rates that are typical of butterfly metapopulations (Conradt et al., 2000), and a potentially widespread dispersal kernel (i.e. “foray search”) that has been reported in a wide variety of species (see Conradt et al., 2003 for a review).     

Human transformities in a global hierarchy: Emergy and scale in the production of people and culture

In emergy research, transformities are of fundamental importance. They are factors that are used to convert the inputs to a process into emergy. Once placed in emergy units, the inputs to any process can then be added together or compared. Furthermore, as a product of an emergy analysis, new transformities for outputs can be used in other analyses. By this process the collection of known transformities grows, and subsequent emergy analyses become more accurate. Human labor is often a critical input to an emergy analysis. Transformities for humans have only been roughly estimated based on education level, and should be judged as first approximations. This paper refines the existing values for human services, using similar techniques, but with some different assumptions. The result is a larger range of human transformities, expanded at both lower and upper ends that range from 7.53E4 to 7.53E13. There are many applications of this knowledge, from improving empirical studies to expositions of hierarchy that more reliably “locate” humans, economic production, and information within energy transformation hierarchies.     

Evaluation of metabisulfite and a commercial steel wool for removing chromium(VI) from wastewater

Efficiency of metabisulfite and a commercial steel wool as reducing agents in the removal of Cr(VI) from wastewaters was evaluated. Chromium(VI) was converted to Cr(III), precipitated with NaOH, and removed by filtration. A reduction of more than 1.0 × 10⁵ and 4.0 × 10⁵ fold in total Cr and the Cr(VI) concentrations, respectively, was observed by employing steel wool masses as low as 0.4420 g to 30-mL solutions of wastewater. Chromium(III) hydroxide obtained after the treatment was recycled and used as marker in cattle nutrition studies. The liquid residue obtained after the treatment was reused as precipitation agent replacing NaOH.     

Biodegradation of phenol by native microorganisms isolated from coke processing wastewater

The present investigation was undertaken to assess the biodegradation of phenol by native bacteria strains isolated from coke oven processing wastewater. The strains were designated ESDSPB1, ESDSPB2 and ESDSPB3 and examined for colony morphology Gram stain characters and biochemical tests. Phenol degrading performance of all the strains was evaluated initially. One of the strains namely ESDSPB2 was found to be highly effective for the removal of phenol, which was used as sole carbon and energy source. From an initial concentration of 200 mg I(-1) it degraded to 79.84 +/- 1.23 mg l(-1). In turn the effect of temperature (20 to 45 degrees C), pH (5-10) and glucose concentration (0, 0.25 and 0.5%) on the rate of phenol degradation by that particular strain was investigated. Observations revealed that the rate of phenol biodegradation was significantly affected by pH, temperature of incubation and glucose concentration. The optimal conditions for phenol removal were found to be pH of 7 (84.63% removal), temperature, 30 degrees C (76.69% removal) and 0.25% supplemented glucose level (97.88% removal). The main significance of the study is the utilization of native bacterial strains from the waste water itself having potential of bioremediation.     

Refueling while flying: foraging bats combust food rapidly and directly to power flight

Flying vertebrates, such as bats, face exceptionally high energy costs during active flapping flight. Once airborne, energy turnover may exceed basal metabolic rate by a factor of up to 15. Here, we asked whether fuel that powers flight originates from exogenous (dietary nutrients), endogenous sources (mostly body lipids or glycogen), or a combination of both. Since most insectivorous bats fly continuously over relatively long time periods during foraging, we assumed that slowly mobilized glycogen, although suitable for supporting brief sallying flights, is inadequate to power aerial insect-hunting of bats. We hypothesized that the insect-feeding Noctilio albiventris rapidly mobilizes and combusts nutrients from insects it has just eaten instead of utilizing endogenous lipids. We used the stable carbon isotope ratio in the bats' exhaled breath (delta13C(brth)) to assess the origin of metabolized substrates of resting and flying N. albiventris in two nutritional conditions: fasted and recently fed. The breath of fasted resting bats was depleted in 13C in relation to their insect diet (delta13C(diet)), indicating the combustion of 13C depleted body lipids. In contrast to this, delta13C(brth) of bats that had recently fed closely matched delta13C(diet) in both resting and flying bats, suggesting a quick mobilization of ingested nutrients for metabolism. In contrast to most non-volant mammals, bats have evolved the ability to fuel their high energy expenditure rates through the rapid combustion of exogenous nutrients, enabling them to conquer the nocturnal niche of aerial insectivory.     

Effect of surfactants on phosphatase level of fresh water fish Labeo rohita

Alterations in the activity of enzymes Acid phosphatase (E.C.3.1.3.2) and Alkaline phosphatase (EC 3.1.3.1) in organs such as liver, gills and muscle of rohu following its exposure to surfactants viz. CTAB, SDS and Triton X-100 were analyzed. Different levels of exposure were given depending on the LC50 value of the surfactant used. Also, the influence of age and weight of the organisms was tested simultaneously. The activity of ACP in the tissues of fish exposed to all the three surfactants showed marked enhancement after exposure; the effect being highest in the liver followed by gill and muscle. Activity levels of ALP in different tissues of the fish exposed to the surfactants also showed an increase. Maximum increase was found in the liver followed by muscle, and gill. The increase in the levels of these enzymes indicates a stressful condition of the fish.