Influence Of Substratum Research Articles

A Typological and Diachronic Analysis of Replication: Body-Part Reflexives in Romance-Lexifier Pidgins and Creoles

Abstract The fact that body-part reflexives (bpr s) are widespread in Romance-lexifier pidgin, creole and mixed (pcm) languages of the Atlantic area has usually been accounted for in terms of substratum influence from West African languages, in which such reflexives are common. However, this approach does not explain why bpr s are also frequently found in Romance-lexifier pcm languages like Zamboanga Chavacano and Malacca Creole, which lack a demonstrable African substrate, are spoken outside the Atlantic area and are in contact with languages that lack bpr s. Drawing on cross-linguistic as well as historical corpus data, this paper argues that the source of bpr s in these languages should be traced back to the late-medieval and early-Renaissance lexifiers. More specifically, it is proposed that speakers of Romance-lexifier pcm languages identified, recapitulated and replicated reflexive-like uses of words such as ‘body’ and ‘head’ in the lexifiers. A number of bridging contexts is argued to have fostered these processes.

Lipase production by three thermophilic fungi


 
 
 Production of lipases by three thermophilic fungi, Thermomyces lanuginosus, Talaromyces luteus and Rhizomucor pusillus was investigated, influence of substratum, pH, temperature, carbon and nitrogen sources on lipase production was also studied. All the three fungi under study produced good amount of lipase constitutively. Lipase production was maximum at 45oC and it was thermostable.
 
 

АНГЛІЙСЬКА МОВА ТА ЇЇ МАЙБУТНЄ: ТРИ СЦЕНАРІЇ

Currently, English claims the status of not just an international, but the first world language. The key role in its dissemination is played not so much by ease of learning, but by the political, economic, scientific, technical and cultural leadership of the Englishspeaking countries. Now there are three times more speakers using English as a second language than those for whom it is native. Almost all language ratings in various parameters give it undoubted superiority. Despite this, few people think about the future of the English language. Some researchers predict that in the future it will forever establish itself as the main or even the only world language (D. Crystal). Other researchers consider its dominance as a temporary phenomenon: from the second half of the XXI century Chinese, Hindi/Urdu, Spanish, and Arabic will compete with it on equal terms for international status in their regions (D. Greddol). One can hardly be sure that in the future the current status of the English language will not change in any way, because earlier all international languages gave up their positions sooner or later. Using the scenario method, the article predicts the long-term prospects for the English language. Three variants of its further development with different results are proposed. Scenario 1: English is rapidly spreading in all countries, in almost all socially significant areas, becomes a single world language and holds this status for an indefinitely long time. Scenario 2: because of spreading on all continents, English experiences the substratum influence of local languages, new variants of it arise, which subsequently leads to its fragmentation with subsequent divergence. Scenario 3: English will retain its integrity, but will lose its leading role in international communication in favor of other languages. The probability of each of the above scenarios is estimated.

Diphthongs in Igbo? Language Contact in the Igbo and Anaang Borderlands

This study examined Anaang substratum influence on Igbo, and how it relates to socio-cultural biographies (such as trade, intermarriage and small-scale migration) amongst Igbo and Anaang speakers in the borderlands. Drawing on ethnographic observation, semi-structured and sound-elicitation interviews with 20 informants made up of Igbo and Anaang speakers, the study identified Anaang substratum influence on Igbo involving the transfer of “vowel-glide” sequences in Anaang to Igbo, which we analysed as “imposition,” and which may build up to the process of diphthongisation in the Igbo language. There are signs of incipient structural diffusion or convergence as revealed in the adoption of the Anaang “glide-vowel” phonotactic feature (for example, occurrence in medial and final positions and co-occurring with plosives and fricatives) in the version of Igbo spoken in the borderlands, as well as occurrence of some “glide-vowel” sequences in initial positions (which goes against Anaang phonotactics) in the version of Anaang spoken in the borderlands. It is concluded that complex linguistic outcomes in the borderlands reveal the typological distance between languages in contact.

Substratum influences uptake of radium-226 by plants

Radium-226, an alpha emitter with half-life 1600 years, is ubiquitous in natural environments. Present in rocks and soils, it is also absorbed by vegetation. The efficiency of 226Ra uptake by plants from the soil is important to assess for the study of heavy metals uptake by plants, monitoring of radioactive pollution, and the biogeochemical cycle of radium in the Critical Zone. Using a thoroughly validated measurement method of effective 226Ra concentration (ECRa) in the laboratory, we compare ECRa values of the plant to that of the closest soil, and we infer the 226Ra soil-to-plant transfer ratio, RSP, for a total of 108 plant samples collected in various locations in France. ECRa values of plants range over five orders of magnitude with mean (min–max) of 1.66 ± 0.03 (0.020–113) Bq kg−1. Inferred RSP values range over four orders of magnitude with mean (min–max) of 0.0188 ± 0.0004 (0.00069–0.37). The mean RSP value of plants in granitic and metamorphic context (0.073 ± 0.002; n = 50) is significantly higher (12 ± 1 times) than that of plants in calcareous and sedimentary context (0.0058 ± 0.0002; n = 58). This difference, which cannot be attributed to a systematic difference in emanation coefficient, is likely due to the competition between calcium and radium. In a given substratum context, the compartments of a given plant species show coherent and decreasing RSP values in the following order (acropetal gradient): roots > bark > branches and stems ≈ leaves. Oak trees (Quercus genus) concentrate 226Ra more than other trees and plants in this set. While this study clearly demonstrates the influence of substratum on the 226Ra uptake by plants in non-contaminated areas, our measurement method appears as a promising practical tool to use for (phyto)remediation and its monitoring in uranium- and radium-contaminated areas.

Living (stained) foraminifera in the Lesser Syrtis (Tunisia): influence of pollution and substratum.

Foraminifera are protozoans with biomineralized tests that can be successfully used as a low cost monitoring tool to assess the health status of marine environments. Living benthic foraminiferal assemblages can provide essential information on natural and/or anthropogenic stresses and provide baseline conditions for studies on fossil material. Several studies have highlighted the negative impact of phosphate treatment industries along the Gulf of Gabes (Lesser Syrtis, Tunisia) on the marine environment. However, only a few studies, based on living (stained) benthic foraminifera, are presently available to assess environmental and/or ecological conditions in this Gulf. Thirty-eight surface sediment samples were quantitatively investigated to identify the dominant living benthic foraminiferal species and potential pollution-sensitive and stress-tolerant species. One-hundred and sixty-one species were identified, and grouped into seven clusters representing different environments within the Gulf. These groups represent polluted settings (Cluster A and B), polluted environments characterized by physicochemical variability (Cluster C), seagrass meadows and “pristine” sites (Cluster D and E) and the region subjected to major industrial impact (Cluster F). The final outlier Cluster, identified the foraminifera barren and all shallow coastal stations. A SIMPER analysis helped identify species with clear and fast responses to environmental perturbations (Ammonia tepida, Amphistegina lessonii, Brizalina striatula, Bulimina marginata, Buliminella elegantissima, Eggereloides scaber, Peneroplis perutusus, Rosalina macropora, Rosalina villardeboana, Trochammina inflata). A comparison with the measured geochemical parameters (TOC, phosphorus in the sediments and heavy metal concentrations in the seawater) has shown that the benthic foraminiferal assemblages are mainly linked to phosphorus, TOC, As and Cd pollution. We also provide here the first compilation of the identified living species in the Lesser Syrtis, their synonyms and digital images of important species.

Role of glucosyltransferase R in biofilm interactions between Streptococcus oralis and Candida albicans

Streptococcal glucosyltransferases (Gtf) synthesize α-glucan exopolymers which contribute to biofilm matrix. Streptococcus oralis interacts with the opportunistic pathogen Candida albicans to form hypervirulent biofilms. S. oralis 34 has a single gtf gene (gtfR). However, the role of gtfR in single and mixed species biofilms with C. albicans has never been examined. A gtfR deletion mutant, purified GtfR, and recombinant GtfR glucan-binding domain were tested in single and mixed biofilms on different substrata in vitro. A mouse oral infection model was also used. We found that in single species biofilms growing with sucrose on abiotic surfaces S. oralis gtfR increased biofilm matrix, but not bacterial biomass. In biofilms with C. albicans, S. oralis encoding gtfR showed increased bacterial biomass on all surfaces. C. albicans had a positive effect on α-glucan synthesis, and α-glucans increased C. albicans accretion on abiotic surfaces. In single and mixed infection of mice receiving sucrose S. oralis gtfR enhanced mucosal burdens. However, sucrose had a negative impact on C. albicans burdens and reduced S. oralis burdens in co-infected mice. Our data provide new insights on the GtfR-mediated interactions between the two organisms and the influence of biofilm substratum and the mucosal environment on these interactions.

Hipoteza Witolda Mańczaka o ugrofińskim substracie w językach bałtyckich

Witold Mańczak’s Hypothesis about the Finno-Ugric Substrate in the Baltic Languages
 The paper discusses Witold Mańczak’s hypothesis concerning a Finnic (particularly Balto-Finnic) substrate in the Baltic languages (Mańczak 1990: 29–38; 1993: 151; 2008: 149–152), as well as J. H. Holst’s critical evaluation of the problem (Holst 2015: 151–173). Mańczak lists as many as ten arguments in support of the substrate theory: According to Meillet (1925: 100–101), the disappearance of the neuter gender in Lithuanian and Latvian occurred under the influence of Balto-Finnic languages, since the category of gender is absent from Finno-Ugric; Old Lithuanian displays secondary local cases (i.e. illative, allative, adessive, ines-sive), formed using postpositions according to the Finno-Ugric pattern (Meillet 1925: 101); The Lithuanian constructions expressing evidentiality (e.g. Lith. nešęs velnias ak-menį) – as well as their Latvian counterparts – appeared due to substrate influence, according to Pisani (1959: 217); The Lithuanian numerals 11–19 ending in -lika (e.g, Lith. vienúolika ‘eleven’, dvýlika ‘twelve’, etc.) are of substrate origin (Pisani 1959: 217); The particle of the Lithuanian imperative -ki or -k (e.g. OLith. dúoki ‘give’) – repro-duces a similar particle known from Finnish, according to some scholars (Топоров, Трубачев 1962: 249–250); The alternation of voiced and voiceless consonants like blekai / plekai ‘tripe’ (Kiparsky 1968: 76–90 lists 200 such doublets in Latvian and 50 in Lithuanian) may be caused by the influence of a Finno-Ugric substratum, since the Finno-Ugric lan-guages used to lack voiced consonants; There are Common Baltic terms of Finno-Ugric origin, e.g. the name for ‘amber’: OPrus. gentars, Lith. giñtaras, Latv. dzĩtars m. ‘amber’ (Bednarczuk 1976: 47–48). The use of the genitive instead of an adjective in East Baltic (e.g. Lith. lietuvių kalba ‘Lithuanian language’, Latv. latviešu valoda ‘Latvian language’), unknown in other Indo-European languages, arose through Balto-Finnic influence – cf. Finnish suomen kieli ‘Finnish language’, Est. eesti keel ‘Estonian language’ (Bednarczuk 1968). The territory of Latvia abounds in hydronyms of Finnic provenance, while in Lithuania we may identify the name Nemunas (chief river in the area) as well as ca. 30 other river names of potential Finno-Ugric origin (Zinkevičius 1984: 155). The non-distinction of grammatical number in third-person finite verb forms in Lithua-nian, Latvian and Old Prussian was, according to some researchers (e.g. Thomason, Kaufman 1988: 243), caused by Balto-Finnic influence. Besides, the present author reviews Holst’s critical paper on the theory of a Uralic substratum in Common Baltic.

Special issue on mechanisms of French contact influence in Middle English: diffusion and maintenance

Recent years have seen a spate of publications that attempt to recontextualise the history of English in contact-linguistic (Miller 2012; Lutz 2013; Durkin 2014) and sociolinguistic terms (Millar 2012), and conversely to confront previous descriptions of contact phenomena with new data and theoretical insights available from situations of language shift and substratum influence (Filppula, Klemola & Paulasto 2008; Vennemann 2011), extensive bilingualism (Schendl & Wright 2011), language acquisition (Ingham 2012) and contact-induced grammaticalisation (Timofeeva 2010). Coupled with advances in our understanding of contact- and acquisition-induced language change (Heine & Kuteva 2005; Jarvis & Pavlenko 2008), and of the role of contact in the varieties of English around the world (Schreier & Hundt 2013), there is a clear need in this area of historical research for scholars to reinvestigate earlier stages of English as a contact language.

Benthic composition influences habitat use and toxicity of coral-dwelling fishes

The distribution and abundance of habitat specialists is often associated with the availability of preferred habitat; however, other environmental features can also influence habitat selection. Coral-dwelling gobies are habitat specialist fishes that depend on the availability of a few key species of coral for their survival and rely on skin toxins to reduce predation risk. This study investigated the influence of benthic substratum around coral colonies on patterns of habitat use and toxicity of two species of coral-dwelling gobies (Gobiodon erythrospilus and Gobiodon histrio) that compete for access to the coral, Acropora nasuta. Field surveys demonstrated that the benthic substratum around A. nasuta coral colonies differed between colonies occupied by G. histrio and G. erythrospilus. Juvenile, single adult and breeding pairs of G. erythrospilus mostly inhabited A. nasuta colonies surrounded by branching corals. In contrast, juvenile and single adult G. histrio associated with A. nasuta coral colonies that had adjacent epilithic algal matrix and G. histrio breeding pairs inhabited colonies surrounded by sand/rubble. Habitat choice experiments demonstrated that both goby species prefer A. nasuta coral colonies with benthic substratum mainly composed by epilithic algal matrix and sand; suggesting that competition for coral colonies in preferred locations could influence patterns of habitat use observed in the field. The substratum around preferred coral colonies also influenced the toxicity levels of associated fishes. Gobies inhabiting A. nasuta coral colonies surrounded by epilithic algal matrix and sand showed higher levels of toxicity than gobies collected from colonies surrounded by branching corals. Given the potential for toxicity level to reduce the risk of predation, this could explain why gobies would compete for access to colonies of the preferred coral species surrounded by epilithic algal matrix and sand. These results show that the habitat use of coral habitat specialist fishes can be affected by the benthic composition around preferred coral colonies and demonstrate how competition for important secondary resources can influence patterns of habitat use.

Comparative surface energetic study of Matrigel® and collagen I interactions with endothelial cells

Understanding of the surface energetic aspects of the spontaneously deposited proteins on biomaterial surfaces and how this influences cell adhesion and differentiation is an area of regenerative medicine that has not received adequate attention. Current controversies surround the role of the biomaterial substratum surface chemistry, the range of influence of said substratum, and the effects of different surface energy components of the protein interface. Endothelial cells (ECs) are a highly important cell type for regenerative medicine applications, such as tissue engineering, and In-vivo they interact with collagen I based stromal tissue and basement membranes producing different behavioral outcomes. The surface energetic properties of these tissue types and how they control EC behavior is not well known. In this work we studied the surface energetic properties of collagen I and Matrigel® on various previously characterized substratum polyurethanes (PU) via contact angle analysis and examined the subsequent EC network forming characteristics. A combinatorial surface energy approach was utilized that compared Zisman’s critical surface tension, Kaelble’s numerical method, and van Oss-Good-Chaudhury theory (vOGCT). We found that the unique, rapid network forming characteristics of ECs on Matrigel® could be attributed to the apolar or monopolar basic interfacial characteristics according to Zisman/Kaelble or vOGCT, respectively. We also found a lack of significant substratum influence on EC network forming characteristics for Matrigel® but collagen I showed a distinct influence where more apolar PU substrata tended to produce higher Lewis acid character collagen I interfaces which led to a greater interaction with ECs. Collagen I interfaces on more polar PU substrata lacked Lewis acid character and led to similar EC network characteristics as Matrigel®. We hypothesized that bipolar character of the protein film favored cell-substratum over cell-cell adhesive interactions which resulted in less rapidly forming but more stable networks.

Assemblages with bifacial tools in Eurasia (third part). Considerations on the bifacial phenomenon throughout Eurasia

Eurasian bifacial series present some common features, but are chiefly characterized by wide-ranging diversity in terms of bifacial technology and blank types, whereas the heavy-duty component presents a limited number of types or categories. Heavy-duty tools are present throughout the geographical areas but the frequency of handaxes and/or cleavers is generally low, except in some regions, where they are made on flakes and/or cobbles/pebbles, on siliceous stones or other rock types. So far, it appears to be generally accepted that bifacial technology became widespread from 800 to 700ka onwards, both for Europe and Asia, except for some earlier occurrences in the Levant and India. It would thus be reasonable to infer that bifacial technology first reached the Levant from Africa before moving toward Asia, then Europe. However, the existing data point to a much more complex reality, suggesting contemporaneous technological worlds, with or without links between them. In the state of current knowledge, and based on the methodology used for analysing lithic series, it is impossible to clearly argue in favour of either a unique phenomenon with movements of hominins or/and ideas from an African source, or to point to evidence of several onsets of bifacial technology over time on a local substratum. The palaeoanthropological background shows the difficulties involved in characterizing the few available hominin fossils and clearly relating them to bifacial technology. The current context suggests that each area should be analysed independently. Accumulative technological processes in some areas due to successive arrivals and the influence of the local substratum, and local onsets must be considered, as these contribute to the diversity of the strategies encountered and the varied forms of bifacial technology.

The role of patellid limpets as omnivorous grazers: a new insight into intertidal ecology

Although patellid limpets are influential grazers on many shores, few studies have characterised their diets in detail. These key species can be found as dominant grazers on rocky shores, but this ecosystem is being transformed due to the increase in infrastructures such as jetties, breakwaters or seawalls by commercial, residential and tourist activities. Increasing knowledge about the ecological effects of these artificial substrates on marine environments is available, and many papers have reported that urban infrastructures support different biota and assemblages and do not act as a surrogate for natural rocky shores. However, little is known about the effect of artificial substrata on marine trophic ecology. The aim of the study was to explore the influence of artificial substrata (breakwaters) on the dietary composition of the common grazer Patella caerulea, to provide data about food resource availability, and its influence on the trophic ecology of limpets. A nested design was used to explore potential differences between natural and artificial shores in Algeciras Bay (Strait of Gibraltar). Additionally, the dietary composition of the endangered limpets Cymbula safiana and Patella ferruginea was studied in a single site. Analyses of the chlorophyll a concentration of the substrate did not show differences between substrata. The analysis of the rock surface by SEM indicated a general prevalence of diatoms and cyanoprokaryotes on all of the substrata. P. caerulea specimens collected from artificial substrata showed a lower number of consumed taxa than those collected from natural rocky shores, whereas the assemblages found in the gut contents also differed between artificial and natural substrata. The diet richness of the three species might be due to the differences in the position of the species on the shore. Our results suggest that limpets are a key group in the top-down control of meiofaunal and macrofaunal populations, due to the presence of several animal taxa in their gut contents in this study, despite the fact that they have traditionally been considered herbivorous grazers that regulate only algal populations in the intertidal regions.

Triggering larval settlement behaviour and metamorphosis of the burrowing ghost shrimp, Lepidophthalmus siriboia (Callianassidae): do cues matter?

Larval settlement and metamorphosis of many estuarine decapod crustaceans are triggered by environmental cues and chemical substances produced by the conspecific population. Here, we examined the influence of substrata and conspecific cues on the stimulation of the megalopal stage of the burrowing ghost shrimp (Lepidophthalmus siriboia) in the following five treatments: (1) adult-conditioned seawater (ACSW), (2) filtered seawater (FSW) + sand, (3) FSW + muddy sand (MS), (4) ACSW + MS and (5) FSW without cues (control). All megalopae settled and exhibited burrowing behaviour in the treatments containing substratum. The percentage of metamorphosis to juvenile was high (≥96%) in all treatments. Megalopae developed significantly faster in the control (5.7days, ±0.9s.d.) than in the remaining treatments (6.8–7.3 days). These findings demonstrated that settlement of L. siriboia megalopae is strongly induced by substrata, whereas their metamorphosis occurs irrespective of the presence or type of exogenous cues associated with estuarine habitat and conspecific adults. This suggests certain flexibility concerning the ontogenetic stage at which recruitment to the benthos occurs. The independence of metamorphic inducers should be important for colonisation of new estuarine areas as well as for recovery and maintenance of viable populations in disturbed habitats where callianassid ghost shrimps are heavily exploited.

Conservation of 87Sr/86Sr isotopic ratios during the winemaking processes of ‘Red’ wines to validate their use as geographic tracer

87Sr/86Sr has been determined in wines, musts grape juices, soils and rocks from six selected vineyards of ‘Cesanese’ wine area. Cesanese is a monocultivar wine from a small region characterised by different geologic substrata, a key locality to test the influence of both substratum and winemaking procedure on the 87Sr/86Sr of wines. Experimental work has been performed on wines from different vintage years to check possible seasonal variations. The data reveal that 87Sr/86Sr does not change through time, to validate the selection of wineries performed, and in addition no isotopic variations are observed during winemaking. Indeed, no significant isotopic variations have been observed in musts and wines. These findings reinforce the hypothesis that the isotopic signature of wines is strongly related to the bioavailable fraction of the soil rather than to its bulk. The data corroborate the possibility that Sr-isotopes of high-quality wines can be used as a reliable tool for fingerprinting wine geographic provenance.

Hydrogeochemical tools applied to the study of carbonate aquifers: examples from some karst systems of Southern Spain

Karst aquifers present hydrogeological characteristics that distinguish them from others such as fractured and granular aquifers. In particular, they are characterized by highly heterogeneous functioning (large temporal and spatial variability), which makes difficult the application of traditional research methods to karst hydrogeology. For this reason, during the last decades, hydrogeochemical tools have been developed for carbonate aquifers characterization by means of spatial and temporal hydrochemical variability, mixing processes (recharge vs. stored water in the system), groundwater origin (saturated/unsaturated zones, epikarst, etc.), karstification degree and, in general, the hydrogeological functioning of karst aquifers. In the present work, some of the most used techniques to study this type of media are applied to pilot sites from South Spain, in order to show hydrogeochemical processes related to karst aquifers functioning: groundwater origin, distribution of its chemical composition, aquifer behavior, water residence time, substratum influence and geochemical modelling. The results display that the combination of different hydrogeochemical tools provides a comprehensive understanding of the functioning of karst systems, which is useful for groundwater management and protection as well as for environmental applications (groundwater ecodependent systems, wetlands, coastal aquifers, etc).

The Northwest of South Asia and beyond: The issue of Indo-Aryan retroflexion yet again

Abstract The Vedic Sanskrit contrast dental : retroflex is widely attributed to Dravidian substratum influence (starting with Pott 1833, 1836). An objection is that retroflexion is explainable by internal developments and that the phonological systems of Sanskrit and reconstructed Dravidian differ considerably (e.g. Bloch 1925; Hock 1975, 1982). Tikkanen (1987, 1988) raises the alternative possibility of a northwestern substrate. I reexamine the evidence and arguments offered so far. The trigger for the internal development of Sanskrit retroflexion is the retroflex sibilant ṣ and its variant ẓ(h), segments absent in Proto-Dravidian. The Northwest, by contrast, has retroflex sibilants; in fact, a triple contrast s : ṣ : ś is widespread and occurs as early as the Prakrits, Eastern Middle Iranian Saka, and even Avestan (with s : š : ṣ̌ : š́). Significantly, it also occurs in Vedic. I argue that the retroflex sibilant, the trigger for Vedic retroflexion, arose in the Northwest, not by contact with Dravidian. The development of retroflex stops can be explained in terms of later convergent developments in peninsular South Asia, developments which in Dravidian also introduced alveolar stops. In the concluding section I discuss the relevance of this account for convergence studies in general.

The influence of clay brick substratum on the inhibitory efficiency of TiO2 nanocoating against biofouling

The goal of this study was to explain the influence of the total porosity and the surface roughness on the susceptibility of clay bricks to biodegradation by phototrophic microorganisms. In addition, this correlation was studied on both specimens treated with TiO2 nanocoating and untreated control specimens. The effect of UV intensity on the photocatalytic power of TiO2 was also investigated.An accelerated fouling test was performed by sprinkling a suspension of Chlorella mirabilis and Chroococcidiopsis fissurarum on sample surfaces. These two test strains were chosen because their representativeness on building clay brick façades subjected to biofouling. The gradual superficial accumulation of algal biomass on treated and control specimens was evaluated by means of image analysis and colour measurement. Two specimens' parameters, namely porosity and roughness, were examined.Results showed that both the specimen microstructure and roughness of the surface play a key role in the colonization of clay bricks because they were able to provide more nutrient to the algal cells anchored to the surface. The TiO2 nanocoating was able to inhibit the biofouling of clay bricks irradiated with UV-A light, except in the case of high porous rough specimens.

Influence of substratum on non-native clam recruitment in Willapa Bay, Washington, USA

Two non-native clam species (Manila clams, Ruditapes philippinarum, and Eastern soft-shell clams, Mya arenaria) vary in density throughout intertidal habitats in Willapa Bay, Washington, USA. We used these species to test a fundamental ecological question, long addressed in marine systems, of whether the observed patterns were due to settlement choice or post-settlement mortality. A series of four experiments revealed habitat-specific mortality of young clams to be the dominant driver of distributions for both species. In contrast, settlement, which occurred over an extended reproductive period (June–Sept), appeared insensitive to substrate modification through additions of rock or shell (Expt 1–3). In Expt 2 and 3, sampled after winter when clams had reached ~1cm shell length, densities were lower in soft sediments characterizing much of the bay, and higher with rock or shell addition, especially with mesh bag protection. In Expt 4, which involved a crossed design of vegetation removal and substrate addition, one-year-old R. philippinarum densities increased with substrate addition more often than M. arenaria, and neither changed in response to removal of vegetation alone. In the case of one substratum, round rock, both vegetation removal and substrate addition were required to raise clam densities. Netting and gravel addition are standard practices in clam aquaculture to protect plantings of larger clams (e.g. >1cm), but in our study substrate modification reduced losses of smaller (<1mm) newly-settled clams. Overall, top-down control appears to be more important than settlement choice in determining local densities of Willapa Bay's non-native clams. Our findings open the possibility of improved aquaculture yields across all substrate types via natural settlement combined with interventions to reduce early losses due to predation.

Persistence of fecal indicator bacteria in sediment of an oligotrophic river: Comparing large and lab-scale flume systems

In this study, both a lab and a large-scale flume system were used to investigate the survival of fecal indicator bacteria (FIB) in bed sediments of an alpine oligotrophic river. To determine the influence of substratum on persistence, survival within 3-cm-deep substratum cages versus on thin, biofilm-covered ceramic tiles was tested. Moreover, the impact of bed shear stress on survival in bed sediments was explored.It was seen that in the lab-scale flume having a very low bed shear stress (0.3 N m−2), E. coli and enterococci survival in 3-cm-deep substratum cages was nearly the same as in a thin biofilm (200 μm). However, in the large-scale flume system characterized by a bed shear stress of 9 N m−2, the added protection of the deeper substratum cages promoted considerably longer survival of E. coli and enterococci than the thin biofilm. Additionally, the FIB removal mechanisms in the two flume systems varied. At the lab-scale, enterococci was seen to persist twice as long as E. coli, while in the large-scale flume the two FIB were removed at the same rate. A comparison of qPCR analyses performed in both flumes suggests that bed sediment erosion and the influence of grazers/predators were responsible for FIB removal from the sediments in the large-scale flume, whereas in the lab flume FIB inactivation caused removal. These results indicate that hydraulic parameters such as bed shear stress as well as the presence of macroinvertebrates in a system are both important factors to consider when designing flumes as they can significantly impact FIB persistence in sediments of fast-flowing, alpine streams.