Yangtse River sediments and erosion rates from source to sink traced with cosmogenic Be: Sediments from major rivers

Estimates of regional erosion and sediment mixing from different sources in the Yangtse River system are presented, based on sand samples collected from major tributaries and the trunk stream, at 23 sites between western Sichuan and the Yangtse Delta. Mixing is estimated from concentrations of Mg, Ca, Sr, Ti, Mn and Fe, which are substantially higher in sand from major tributaries in the western Yangtse River catchment than from tributaries in the eastern catchment. Intermediate concentrations occur in sand from the Yangtse Delta, both for modern samples from the surface and for early Holocene samples from drill holes. Mixing ratios indicate that 35 ± 5% of sand in the delta came from eastern sources. A similar result was obtained using cosmogenic ¹⁰Be in quartz grains as a tracer of mixing. Regional erosion rate estimated from ¹⁰Be in sand grains from high mountain catchments of the western Yangtse River are mostly similar to rates based on sediment gauging but are sometimes higher, and range to over 700 m Ma^− 1, while ¹⁰Be measured at upper Yangtse River tributaries on the northeast Tibetan plateau gave rates of 20-30 m Ma^− 1. For the eastern catchments, ¹⁰Be measurements from quartz sand and sediment gauging both gave rates of 30-70 m Ma^− 1. Eroding at this rate, the eastern catchments could not supply more than 20% of the sediment in the delta, in contrast with 35% estimated from geochemical fingerprints. The relative input from eastern sources may have been higher in Late Pleistocene times, under a different climatic regime, and reworking of Pleistocene deposits may still be in progress.     

Ecogenotoxicological studies for an early toxicity screening and monitoring in Epinephalus chlorostigma and Scamberomorus commerson

The study was planned to investigate DNA fragmentation in fish to screen aquatic toxicity and in Epinephalus chlorostigma and Scamberomorus commerson collected from Red sea near Jizan, Saudi Arabia from three locations “(Corniche North park: “16.92161, 42.54631; Jizan Port: 16.874, 42.54952” N and Jizan Economic City: 17.26589, 42.34738“ ”)“ were used as a case study for the application of comet assay. The study area of the Red Sea is polluted due to anthropogenic activities and the disposal of wastes from multiple sources. Comet and micronucleus assays were used to detect genotoxicity in these fish species harvested from three sites. The concentration of Pb, Cr, Zn, Mn, Cu, Cd, Sn, and Hg was higher in the water samples collected from the polluted site compared to the non-polluted site of the Red sea. Comet assay for S. commerson showed significant (p < 0.05) genetic damage about 44.33 ± 3.03% DNA in comet tail at site S1. It was subsequently reduced to 31.71 ± 3.52% and 22.11 ± 2.52% at sites S2 and S3. E. chlorostigma also showed significant DNA in comet tail as 17.34 ± 2.19%, 11.87 ± 3.01%, and 36.41 ± 3.98% at site S1-S3, respectively. Significant (p < 0.05) DNA damage was observed in the fishes procured from non-polluted locations and upstream locations. The micronucleus induction in E. chlorostigma was recorded as 23.20 ± 4.19 and 2.20 ± 0.58%, respectively, non-polluted and polluted sites. S. commerson exhibited significant differences between polluted and non-polluted sites (44.80 ± 3.73 and 8.20 ± 2.20‰) polluted and upstream (44.80 ± 3.73 and 20.60 ± 4.02‰), respectively. A significant difference was obtained between E. chlorostigma and S. commerson for nuclear abnormalities S. commerson showed higher frequencies for nuclear deformities than E. chlorostigma. S. commerson showed substantial micronucleus induction frequencies collected from an area of low pollution intensity (upstream). This study showed that E. clorostigma and S. commerson could be successfully used as a bioindicator to determine the health of the Red Sea through the most specific assays such as comet and micronucleus tests as an early warning and to devise the monitoring strategies to ensure a safe supply of fish for human consumption.     

Home range estimates for squaretail coralgrouper, Plectropomus areolatus (Rüppell 1830)

The aim of the study was to estimate home range areas and distance of movement away from a squaretail coralgrouper (Plectropomus areolatus) spawning aggregation site located within a small-scale 1.5 km² Marine Protected Area (MPA) in Pohnpei, Micronesia. Fifteen P. areolatus were acoustically tagged and re-located within a ca. 50 km² search area over a 4-month period that included reproductive and non-reproductive months. All relocated fish were found in areas of moderate to high coral cover either on the fore reef or inside the lagoon in home ranges of 0.048 ± 0.018 km² (μ ± S.E.). Variability in home range area (0.004–0.12 km²) and distance of movement from aggregation sites following spawning (0.02–23.0 km; 5.3 ± 3.6 km, μ ± S.E.) was observed, but did not appear to be sex specific. Five of the six relocated individuals were found within 0.02–6.1 km of the aggregation. This evidence and that from recent tag-recapture studies of epinephelids suggest that a substantial proportion of individual P. areolatus spawning populations reside within close proximity to their respective aggregation sites. Reproductive populations could be protected by MPAs of moderate scale (10 s of km²) that include aggregation sites, migratory corridors and adjacent home range habitats.     

Plasticity of Least Tern and Piping Plover nesting behaviors in response to sand temperature

Birds that nest on the ground in open areas, such as Piping Plovers (Charadrius melodus) and Interior Least Terns (Sternula antillarum athalassos), are exposed to high temperatures in thermally stressful environments. As a result, some ground-nesting avian species have adapted behavioral strategies to maintain thermal regulation of eggs and themselves. We assessed the impact of sand temperature on shorebird nesting behaviors by installing video cameras and thermocouples at 52 Least Tern and 55 Piping Plover nests on the Missouri River in North Dakota during the 2014–2015 breeding seasons. Daily duration and frequency of shading behaviors exhibited a nonlinear relationship with temperature; therefore, we used segmented regressions to determine at what threshold temperature (mean temperature = 25.7^⸰C for shading behavior daily frequency and mean temperature = 25.1^⸰C for shading behavior daily duration) shorebird adults exhibited a behavioral response to rising sand temperatures. Daily nest attendance of both species decreased with increasing sand temperatures in our system. Frequency and duration of daily shading behaviors were positively correlated with sand temperatures above the temperature threshold. Piping Plovers exhibited more and longer shading behaviors above and below the temperature thresholds (below: frequency = 10.30 ± 1.69 se, duration = 7.29 min ± 2.35 se; above: frequency = 59.27 ± 6.87 se) compared to Least Terns (below: frequency = −1.37 ± 1.98 se, duration = −0.73 min ± 1.51 se; above: frequency = 31.32 ± 7.29 se). The effects of sand temperature on avian ground-nesting behavior will be critical to understand in order to adapt or develop recovery plans in response to climate change.     

Stratigraphy and palaeoenvironmental implications of Pleistocene and Holocene aeolian sediments in the Lhasa area,southern Tibet (China)

Along the middle and lower reaches of the Kyichu River and its tributaries (Lhasa area, southern Tibet), a multidisciplinary study was carried out in order to investigate the areal distribution, sedimentological properties, ages and palaeoenvironmental implications of aeolian deposits including intercalated palaeosols. This research was initiated to investigate to what extent southern Tibet is influenced by past human activity, as even recent evaluations perceive the present treeless desertic environment as natural. Fifteen profiles were recorded at an altitude of 3540–4580 m a.s.l. with subsequent sedimentological, geochronological (OSL, AMS ¹⁴C) and palaeobotanical (charcoal) analyses. Sediment properties of both loesses and aeolian sands reveal an origin from aeolian sorting of nearby fluvial deposits. The calculated ages are the oldest obtained thus far on aeolian sediments from southern and interior Tibet, revealing natural aeolian sedimentation before and around the Last Glacial Maximum (c. 20 ka). However, a distinct portion of Late Holocene sandy aeolian sediments also occurs. Both the evidence for the aeolian dynamics (widespread Pleistocene loess and aeolian sand deposition, local Late Holocene aeolian sand deposition, modern reactivation of widespread Pleistocene aeolian sands) and the palaeobotanical findings (Late Holocene vegetation change from a tree-bearing to a widely treeless landscape) provide evidence that the Lhasa area was strongly influenced by human activity since at least the Late Neolithic (c. 4200 cal yrs BP). Thus the present-day desertic environment might not primarily be a result of the semiarid climate or the high-altitude conditions, but rather of activities of the humans and their collateral effects. However, once established, this semi-natural ecosystem persisted, controlled by strong grazing, firewood extraction, erosion and harsh edaphic conditions, preventing the recovery of trees.     

Linkages between coral assemblages and coral proxies of terrestrial exposure along a cross-shelf gradient on the southern Great Barrier Reef

Coral core records, combined with measurements of coral community structure, were used to assess the long-term impact of multiple environmental stressors on reef assemblages along an environmental gradient. Multiple proxies (luminescent lines, Ba/Ca, δ¹⁵N) that reflect different environmental conditions (freshwater discharge, sediment delivery to the nearshore, nutrient availability and transformations) were measured in Porites coral cores collected from nearshore reefs at increasing distance from the intensively agricultural region of Mackay (Queensland, Australia). The corals provide a record (1968–2002) of the frequency and intensity of exposure to terrestrial runoff and fertilizer-derived nitrogen and were used to assess how the present-day coral community composition may have been influenced by flood-related disturbance. Reefs closest to the mainland (5–32 km offshore) were characterized by low hard coral cover (≤10%), with no significant differences among locations. Distinct annual luminescent lines and elevated Ba/Ca values (4.98 ± 0.63 μmol mol⁻¹; mean ± SD) in the most inshore corals (Round Top Island; 5 km offshore) indicated chronic, sub-annual exposure to freshwater and resuspended terrestrial sediment that may have historically prevented reef formation. By contrast, corals from Keswick Island (32 km offshore) indicated episodic, high-magnitude exposure to Pioneer River discharge during extreme flood events (e.g., 1974, 1991), with strongly luminescent lines and substantially enriched coral skeletal δ¹⁵N (12–14‰). The reef assemblages at Keswick and St. Bees islands were categorically different from all other locations, with high fleshy macroalgal cover (80.1 ± 7.2% and 62.7 ± 7.1%, respective mean ± SE) overgrowing dead reef matrix. Coral records from Scawfell Island (51 km offshore) indicated little exposure to Pioneer catchment influence: all locations from Scawfell and further offshore had total hard and soft coral cover comparable to largely undisturbed nearshore to middle shelf reefs of the southern Great Barrier Reef.     

Importance of advective mass transfer and sediment surface area for streambed microbial communities

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Oxidative stress and DNA damage in relation to transition metals overload in Abu-Qir Bay,Egypt

The aim of the present study is to evaluate the transition metals overload in Abu-Qir Bay in Egypt, as compared to a less polluted area (reference area) through some biomarkers of oxidative stress. Catalase enzyme activity, malondialdehyde (MDA) concentration and DNA damage (number of apurinic/apyrimidinic sites) were the tested biomarkers. The levels of iron and copper in Mugil cephalus liver tissues were significantly higher in samples from the polluted area as compared to the reference area: Fe: 407 ± 38 vs. 216 ± 21 μg/g wet wt; p = 0.008, Cu: 54 ± 6 vs. 17.7 ± 4 μg/g wet wt; p = 0.0001. This could account for the observed increase in MDA concentration (15.7 ± 5.7 vs. 2.5 ± 0.5 U/g; p = 0.035), and the elevated number of AP sites (13.9 ± 2.6 vs. 0.37 ± 0.2 AP site/1 × 10⁵ bp; p = 0.0001). Similarly, the activity of catalase enzyme responsible for the cellular defense was significantly high (58.3 ± 12.2 vs. 28.4 ± 4.0 U/mg; p = 0.032). The present data indicated a clear relationship between the pollution degree of the above marine environment and both biochemical and molecular responses of the piscine system.     

Aspects of the population ecology of Lucinomaborealis (L.) (Bivalvia) in Raunefjorden,Western Norway

2194 Lucinoma borealis (L.) were obtained from 99 quantitative (0.2 m²) samples of substratum (stratified random sampling) collected between November 1975 and October 1976 in the archipelago of Eggholmane ≈20 km south of Bergen. The depth range of the 20900 m² area was 0.3–13.3 m, and the bottom sediment (fine to very coarse sand) was rich in calcium carbonate. The highest density was found in the deep (≈ 8–13 m) sub-areas, with fine sediment (median grain-size diameter ≈ 0.3–0.5 mm). L. borealis was the most abundant bivalve species in the area studied (59.6%, by number). The average density was 22.2 (C.I. ± 5.4) ind. · 0.2 m ^?2, and the biomass was 690 (C.I. ± 116) mg AFDW · 0.2 m ^?2. The average size of animals found in shallow water (coarse sediment), with low abundance, was markedly larger than that of those from deeper water. Adults from shallow water consisted of 49.5% females, but in deep water the corresponding figure was only 38.6%.According to the data, spawning in deep water occurred in June, August–September, and possibly also in January–February. The spawning period in shallow water was more diffuse and uncertain. The egg diameter of 123.75 (C.I. ± 1.59) μm, indicates a lecithotrophic development. Maturation occurred at a shell length of 10–13 mm, and the largest animal found was 34.3mm long. The shell of L. borealis grows allometrically.     

Most probable number quantification of hypophosphite and phosphite oxidizing bacteria in natural aquatic and terrestrial environments

Concentrations of hypophosphite and phosphite oxidizing bacteria were found to be high, relative to bacterial concentrations growing on phosphate, in sediment and soil during winter and summer seasons from 12 common terrestrial and aquatic sites using a most probable number method. The percent of total culturable bacterial concentrations that could use these reduced phosphorus compounds as a sole source of phosphorus were as follows: hypophosphite, 7–100%; phosphite, 10–67%; aminoethylphosphonate, 34–270%. The average MPN/g (±SEM) was as follows: phosphate, 6.19 × 10⁶ (±2.40 × 10⁶); hypophosphite, 2.61 × 10⁶ (±1.35 × 10⁶) phosphite, 1.91 × 10⁶ (±1.02 × 10⁶); aminoethylphosphonate, 3.90 × 10⁶ (± 1.95 × 10⁶). Relatively high concentrations of reduced phosphorus oxidizing bacteria were found in both pristine sites and sites with urban and agricultural disturbance. Concentrations of reduced phosphorus oxidizing bacteria in anoxic sediments and soil were equivalent. Our data indicate that reduced phosphorus oxidizing bacteria are abundant in the environment and provide strong evidence for the importance of bacterial P oxidation in nature.     

Benthic Distribution of Sewage Sludge Indicated by Clostridium perfringens at a Deep-Ocean Dump Site

Clostridium perfringens in sediment samples collected at the Deep Water Municipal Sewage Sludge Disposal Site (also called the 106-Mile Site), off the coast of New Jersey, was enumerated. The counts of C. perfringens found in sediment samples collected within and to the southwest of the 106-Mile Site were significantly elevated (P < 0.01) compared with counts of samples from reference stations of similar depth (2,400 to 2,700 m), topography, and distance from the continental shelf, indicating that the benthic environment was contaminated by sewage dumping at this site. Low counts of C. perfringens in sediment samples collected at stations between the base of the continental shelf and the 106-Mile Site indicated that coastal runoff was not a significant source of contamination. Elevated counts were observed for samples up to 92 km to the southwest, whereas low counts were obtained for samples from stations to the east of the 106-Mile Site. This distribution is consistent with previous model predictions of sludge deposition. In areas heavily impacted by sludge dumping, C. perfringens counts were generally highest in the top 1 cm of sediment and exceeded 9,000 CFU g (dry weight) of sediment^-1. The patterns of C. perfringens dispersal observed in this study have proved useful for selection of heavily impacted areas and control stations for further ecological evaluation by a multidisciplinary research team.     

A maze-lover's dream: Burrow architecture,natural history and habitat characteristics of Ansell's mole-rat (Fukomys anselli)

The Ansell's mole-rat (Fukomys anselli, Bathyergidae) is a small-sized social subterranean rodent whose distribution is confined to the Lusaka area in Zambia. It is an established model species for various laboratory studies, but until now the knowledge of its biology under natural conditions has been limited. Here, we provide the first comprehensive natural history and ecological data on a free living population from Miombo woodland. The Ansell's mole-rat lives in groups of up to 13 individuals (mean 9.7 ± 2.5; N = 9 complete, fully established family groups) with a single breeding pair per group. The family groups occupy very large and complex burrow systems consisting of 0.5–2.8 km of tunnels (mean = 1.2 ± 0.6 km, N = 15), which are densely branched and reticulated especially around nests. Burrow systems of neighbouring family groups were often interconnected by a freely passable tunnel, which has never before been documented in any African mole-rats. Mole-rat food density in the study area was relatively low (10.0 ± 8.4 m^?2) but its biomass was large (457 ± 889 g m^?2). This, together with a relatively workable soil (cone resistance = 529 ± 26 N cm^?2 at the end of June, with 10% soil humidity), indicates moderate ecological conditions, which disagrees with the aridity food-distribution hypothesis (AFDH) considering small body size and sociality in bathyergids adaptations to harsh environments.     

Temporal and spatial variations of biodeposits—A preliminary investigation of the role of fecal pellets in the Sylt-Rømø tidal area

The fecal pellets ofHeteromastus filiformis andHydrobia ulvae are abundant on the sediment surface of the Sylt-Rømø tidal flats. AlthoughCerastoderma edule is present in most parts of the study area, only small amounts of its pellets could be found. Fecal pellets are non-randomly distributed in the study area. Large amounts ofH. ulvae pellets are found in the mud flats and smaller amounts in the mised flats and sand flats, whereH. filiformis pellets predominate as biogenic component. This distribution pattern varies with time under the influence of environmental factors. Marked temperature fluctuations provide seasonal signals reflecting distinct patterns. The results show a net balance of biodeposit components in the sediment. This could be a result of the sheltered location of the area and this fits in well with the mostly stable sedimentological picture.     

Mucous sheet production in Porites: an effective bioindicator of sediment related pressures

Some coral species of the genus Porites can produce thick mucous sheets that partially or completely envelope the colony’s surface. This phenomenon has been reported many times, but the cause and ecological significance remains unclear. In this study, sheet production was examined in response to elevated suspended sediment concentrations associated with a large-scale, extended dredging project on a coral reef. Approximately 400 corals at 16 locations situated from 0.2–33 km from the excavation area were examined at fortnightly intervals over the 1.5 year dredging campaign. Mucous sheets were observed on 447 occasions (from 10,600 observations), with average mucous prevalence ranging from 0–10%. Overall 74 ± 5% of the colonies <1.5 km from the dredging produced one or more sheets. High levels of mucous coverage (≥95% of the colony surface) was observed on 68 occasions, and 82% of these occurred at sites close to the dredging. Approximately 50% of colonies produced ≥3 sheets over the monitoring period, and 90% of these were located close to the dredging. In contrast, at distantly located reference sites (>20 km away), mean mucous sheet prevalence was very low (0.2% ± 0.1), no colonies produced more than 1 sheet, and only 1 colony was observed with high mucous coverage. In a laboratory-based experiment, explants of Porites spp. exposed to fine silt also produced mucous sheets (105 sheets recorded in 1100 observations), with nearly 30% of the fragments exposed to repeated sediment deposition events of 10 and 20 mg cm⁻² d⁻¹ producing 2 new sheets over the 28 day exposure period. These multiple lines of evidence suggest a close association between mucous sheet formation and sediment load, and that sheet formation and sloughing are an additional mechanism used by massive Porites spp. to clear their surfaces when sediment loads become too high. These results suggest that mucous sheet formation is an effective bioindicator of sediment exposure.     

Downscaling patterns of complementarity to a finer resolution and its implications for conservation prioritization

Given species inventories of all sites in a planning area, integer programming or heuristic algorithms can prioritize sites in terms of the site's complementary value, that is, the ability of the site to complement (add unrepresented species to) other sites prioritized for conservation. The utility of these procedures is limited because distributions of species are typically available only as coarse atlases or range maps, whereas conservation planners need to prioritize relatively small sites. If such coarse‐resolution information can be used to identify small sites that efficiently represent species (i.e., downscaled), then such data can be useful for conservation planning. We develop and test a new type of surrogate for biodiversity, which we call downscaled complementarity. In this approach, complementarity values from large cells are downscaled to small cells, using statistical methods or simple map overlays. We illustrate our approach for birds in Spain by building models at coarse scale (50 × 50 km atlas of European birds, and global range maps of birds interpreted at the same 50 × 50 km grid size), using this model to predict complementary value for 10 × 10 km cells in Spain, and testing how well‐prioritized cells represented bird distributions in an independent bird atlas of those 10 × 10 km cells. Downscaled complementarity was about 63–77% as effective as having full knowledge of the 10‐km atlas data in its ability to improve on random selection of sites. Downscaled complementarity has relatively low data acquisition cost and meets representation goals well compared with other surrogates currently in use. Our study justifies additional tests to determine whether downscaled complementarity is an effective surrogate for other regions and taxa, and at spatial resolution finer than 10 × 10 km cells. Until such tests have been completed, we caution against assuming that any surrogate can reliably prioritize sites for species representation.     

Foraminiferal assemblage indices: A comparison of sediment and reef rubble samples from Conch Reef,Florida, USA

Benthic foraminiferal assemblages are increasingly utilized as indicators of water and sediment quality in coastal-marine environments. Most reef-dwelling foraminifers live on firm substrata such as reef or phytal surfaces, while most assessments have examined assemblages from sediments. This case study compared relative abundances of total foraminiferal-shell assemblages between sediment and phytal/rubble samples collected from one reef within one week. A total of 117 species within 72 genera were identified, with the same taxa in both sample sets in different proportions. Larger benthic foraminifers and some agglutinated taxa were concentrated about 1.5–3 fold in sediment samples, while nearly two-thirds of small, fragile shells were lost. Several common indices were compared, including Taxonomic Richness (number of genera), Shannon (H), Simpson's (D) and Fisher (α) diversity indices, Evenness (E), and the FORAM Index (FI). Highly significant differences (p < 0.001) between shell assemblages from 13 sets of phytal/rubble substrata and sediments were found in mean number (± standard deviation) of genera (49 ± 4 vs. 34 ± 10) and mean FI (5.6 ± 0.8 vs. 3.6 ± 0.4); both reflecting greater relative abundances of smaller foraminifers in the rubble samples. Fisher diversity was marginally significant (p = 0.05); other indices showed no significant differences between sample types. Although assessment of total assemblages is substantially less costly than distinguishing between specimens that were live or dead when collected, many researchers report those distinctions. The results of our study provide insight that can assist interpretations of studies that use live assemblages to calculate the FI, rather than total assemblages for which it was originally developed.     

Sediment oxygen demand and benthic foraminiferal faunas in the Arabian Gulf: A test of the method on a siliciclastic substrate

In this study, we investigated the relationship between environmental parameters (water and sediment) and benthic foraminiferal assemblages found in nearshore siliciclastic sediment in the Arabian Gulf. Nearshore marine water and sediment samples were collected from a beach on the Gulf of Bahrain located south of Al Khobar, Saudi Arabia. The water samples were analyzed for biochemical oxygen demand (BOD₅) and other chemical analyses. The sediment samples were tested for sediment oxygen demand (SOD) and heavy metal analysis. Results showed the BOD₅ levels were below the detection limit (<1 ppm), while the mean SOD value was 0.97 ± 0.08 g/m²·day. The water and sediments were unpolluted and free of eutrophic enrichment, while the sediment was anoxic. The two most common genera in the benthic foraminiferal assemblage, Ammonia and Elphidium, are typical of shallow water sandy substrates. This is the first reported comparison between SOD and benthic foraminiferal assemblages.     

Modelling nearshore intertidal habitat use of young-of-the-year Pacific sand lance (Ammodytes hexapterus) in Barkley Sound, British Columbia, Canada

The Pacific sand lance (Ammodytes hexapterus) is an ecologically important prey species for many vertebrate marine predators in the Pacific Northwest. In this study, we examined the use of intertidal habitat by young of the year (YOY) sand lance in Barkley Sound, British Columbia. We selected 14 of the original 29 independent environmental variables for modelling based on univariate analysis for variable selection. These were then used to model sand lance presence-absence using a classification tree approach. Based on our models we found that sand lance avoided mud and intertidal eelgrass. For sites that had very little mud and no intertidal eelgrass, sand lance preferred sediment size mean ≥1,918 μm or sites with sediment size mean ≤1,918 μm but with relatively well sorted sediment (sorting values ≤2.56 SDs, used as a heterogeneity index of the substrate grain size). Adjacent subtidal characteristics were not found to be important at this scale of study. This suggests intertidal substrate characteristics and presence-absence of intertidal eelgrass are the main influences on occurrence of YOY in the intertidal. Our results support the hypothesis that sand lance are associated with particular sediment types, however intertidal sediment types used by sand lance in our study differ from known preferences of sand lance for subtidal sediment types. This difference may be due to unique habitat constraints for intertidal versus subtidal regions. Although it is unknown if the results of this study are widely applicable, the results begin to identify intertidal habitat features that are important for Pacific sand lance.     

PCR-based identification of thermotolerant free-living amoebae in Italian hot springs

Several thermal areas, also used for leisure purposes, may represent suitable habitats for free-living amoebae (FLAs), but few studies have been carried out in search for these organisms. The aim of this study was to assess the presence and distribution of FLAs by culture detection and molecular identification, over a one year-round sampling of two sites in Central Italy. Two geothermal springs (Site A and Site B) were investigated for a total of 36 water samples. Four sets of primers were used to amplify FLA DNA from all cultures positive for amoebic growth at both 37 °C and 45 °C. Overall, 33 (91.6%) water samples produced PCR amplification. Eleven taxa were identified. The array of identified species varied over the sampling period, and differed between the two hot springs, Site A harbouring 11 taxa compared to 5 of site B. However, both sites were characterized by the most common species Vermamoeba vermiformis and Naegleria australiensis. Acanthamoeba genotypes T4 and T15 were found at low frequency. Differences in the composition between the two sites could reflect environmental changes in biotic and chemical/physical parameters. From a public health perspective, the detection of potentially pathogenic amoebae could unveil a potential risk for humans.     

Influence of sediment characteristics on density and distribution of Ocypodoid crab burrows (superfamily: Ocypodoidea) along the coastal areas of Pakistan

Crabs belong to the superfamily Ocypodoidea are a significant component of benthic fauna and considered as ecosystem engineers because of their dynamic role as an active burrower in mangrove and estuarine environment. The current investigation was to evaluate the crab burrow density, diameter and total area of burrow opening along the coast of Pakistan. The variations in burrow properties and their relation to sediment characteristics were also evaluated to recognize the most influencing variables of sediments that effects on crab burrows. All crab burrow and sediment characteristics differed significantly (p < 0.05) among the monitoring sites. Regression analysis showed that crab density was significantly correlated with burrow density (P < 0.001). Moreover, burrow density was noticed significantly greater (p < 0.05) than crab density. Pearson correlation analysis reveals that moisture, porosity, organics, sand and mean grain size observed as most influencing the features of sediment to determine the ecological functioning of crab burrows in mangrove and mudflats of Pakistan.