Relative Abundance

The seismicity depth distribution in the central and southern East African Rift System (EARS) is investigated using available catalogs from local, regional and global networks. We select well-determined events and make a re-assessment of these catalogs, including a relocation of 40 events and, where necessary, a declustering. About 560 events are finally used for determining foci depth distribution within 6 areas of the EARS. Assuming that short-term deformation expressed by seismicity reflects the long-term mechanical properties of the lithosphere, we build yield strength envelopes from seismicity depth distribution. Using brittle and ductile laws, we predict the strength percentage spaced every 5 km (or sometimes 2 km) in the crust, for a given composition and a specific geotherm, and constrain it with the relative abundance of seismicity. Results of this modeling indicate significant local and regional variations of the thermomechanical properties of the lithosphere which are broadly consistent with previous studies based on independent modelings. In order to explain relatively deep earthquakes, a highly resistant, mafic lower crust is generally required. We also find evidence for changes in the strength magnitude and in the depth of the brittle-ductile transitions which are clearly correlated to tectonic provinces, characterized by contrasted thermal gradients and basement types. A clear N-S increase and deepening of the peak strength level is evidenced along the eastern branch of the EARS, following a consistent southward migration of rifting sincẽ 8 Ma. We also detect the presence of a decoupling layer in the Kenya rift, which suggests persisting influences of the deep crustal structures (Archaean and Proterozoic) on the behavior of the extending crust. More generally, our results suggest that seismicity peaks and cut-off depths may provide good proxies for bracketing the brittle-ductile transitions within the continental crust.

The golden cownose ray, Rhinoptera steindachneri, was one of the most abundant species landed in artisanal elasmobranch fisheries in the northern Gulf of California (Baja California and Sonora) and Bahía Almejas, Mexico during 1998-1999. In the northern Gulf of California, R. steindachneri was most frequently observed during summer months (11.4% of elasmobranch landings, catch per unit effort (CPUE) = 6.8 individuals/vessel trip) and was rare during winter (0.1%, CPUE = 0.1). In Bahía Almejas, its relative abundance was greater during August (5.2%) than June (0.3%), a trend also evident in CPUE (August = 1.2, June = 0.1). The mean size of R. steindachneri landed in the Gulf of California was 64.3 ± 12.8 (SD) cm disc width (DW). Median size at maturity for Gulf of California specimens was similar for females (70.2 cm DW) and males (69.9 cm DW). Fecundity was found to be one offspring per female, with parturition estimated to occur from late June-August. Size at birth was estimated at 38-45 cm DW after a gestation period of approximately 11-12 months. Greater maximum sizes (to 104 cm DW) and embryo sizes (to 43 cm DW) were observed in Bahía Almejas. The large size at maturity, low fecundity, and long gestation period determined for R. steindachneri indicate that this species could be particularly susceptible to overexploitation.

Plant litter and the microbial biomass are the major parent materials for soil organic matter (SOM) formation. Plant litter is composed of complex mixtures of organic components, mainly polysaccharides and lignin, but also aliphatic biopolymers and tannins. The composition and relative abundance of these components vary widely among plant species and tissue type. Whereas some components, such as lignin, are exclusively found in plant residues, speci®c products are formed by microorganisms, e.g. amino sugars. A wide variety of chemical methods is available for characterizing the chemical composition of these materials, especially the chemolytic methods, which determine individual degradation products and solid-state 13 C NMR spectroscopy, that gives an overview of the total organic chemical composition of the litter material. With the development of these techniques, an increasing number of studies are being carried out to investigate the changes during decay and the formation of humic substances. An overview is given on the amount of litter input, the proportion of various plant parts and their distribution (below-ground/above-ground), as well as the relative proportion of the different plant tissues. Major emphasis is on the organic chemical composition of the parent material for SOM formation and thus this paper provides information that will help to identify the changes occurring during biodegradation of plant litter in soils. q

The paper describes studies of post-fire succession in heathland vegetation in N.E. Scotland, dominated by Calluna vulgaris. A preliminary model (Legg, 1978) suggested good agreement between simulation of succession on the basis ofa Markov chain and observations of stands at different stages of development after burning, at least in the earlier stages. Vegetation transitions are currently being recorded in permanent plots on burnt areas. First results confirm the view that (a) the post-fire succession has the properties ofa Markov process, (b) this type of model remains valid when constructed from records of actual transitions, rather than data obtained by inference from evidence of transition. Comparing successional events in stands where, at the time of burning, the Calluna population was in pioneer-, building-, mature-and degenerate phases, shows that transition matrices generally agree with the Markov hypothesis, but not in the case of stands where Calluna was degenerate when burnt. The composition of establishing vegetation ! year after fire is not confined to species normally associated with the early stages of succession, but reflects the composition of the stand before burning. Redevelopment after fire is described in terms of an initial floristic composition of species with strategies permitting early re-establishment, selected by the recurrence of the fire factor. Subsequent transitions represent changes in their relative abundance due to differing growth properties and competitive interactions. This interpretation applies only under conditions of recurrent incidence of fire (normally once in 10-15 yr). If fire does not recur, Calluna stands pass into the degenerate phase, where changes in the nature of relay floristics may come into play (e.g. with tree colonization).

INTRODUCTION 1.1. Scope of the study 1.1.1. Hypothesis 1.1.2. Objectives 1.2. Structure of Dissertation 1.3 References CHAPTER TWO: PALEOENVIRONMENTAL RECONSTRUCTION OF THE ASBOLE FAUNA USING STABLE ISOTOPES, BUSIDIMA FORMATION, AFAR, ETHIOPIA 2.1. Introduction 2.2. Controls on the isotopic composition of tooth enamel 2.1.1. Carbon Isotope 2.1.2. Oxygen Isotope 2.3. Geological context of the Asbole Fauna 2.4. Methods 2.5. Carbon isotope, results and interpretation 15 2.5.1. Rhinocerotidae 2.5.2. Elephantidae 2.5.3. Equidae 2.5.4. Suidae 2.5.5. Giraffidae 2.5.6. Hippopotamidae 2.5.7. Bovidae 2.6. Paleoenvironmental interpretations based on faunal abundance 2.7. Faunal-abundance-weighted δ 13 C ecosystem value 2.8. Oxygen isotopic composition of tooth enamel 2.8.1. Observed δ 18 O enamel values 30 2.8.2. Estimating paleo-aridity using δ 18 O enamel 2.9. Conclusions 2.10. References ii CHAPTER THREE: DIETARY AND PALEOENVIRONMENTAL RECONSTRUCTION USING STABLE ISOTOPES OF HERBIVORE TOOTH ENAMEL FROM MIDDLE PLIOCENE DIKIKA, ETHIOPIA: IMPLICATION FOR AUSTRALOPITHECUS AFARENSIS HABITAT AND FOOD RESOURCES 45 3.1. Introduction 3.2. Background 3.3. Geological context 3.4. Methods 3.4.1. Sample collection 3.4.2. Sample treatment and isotopic analysis 3.5. Interpretation of carbon and oxygen isotopes 3.6. Results 3.6.1. Carbon isotopic composition by taxa 52 3

The pK a constants and relative abundances of unionized and ionized forms of Montelukast sodium {the sodium salt of 2-[1-[[(1R)-1-[3-[2-(7-chloroquinolin-2-yl) ethenyl] phenyl]-3-[2-(2-hydroxypropan-2-yl)phenyl]propyl]sulfanylmethyl]cyclopropyl] acetic acid} and Levodropropizine {(2S)-3-(4-phenylpiperazin-1-yl)propane-1,2-diol} were determined potentiometrically from measurements at various pHs. These determinations were in order to relate their pK a values with their bioavailability and to provide chemical data to be used in their analysis.

Microbial concentrations of denitrifiers, pseudomonads, and monoaromatic petroleum hydrocarbon (BTX) degraders were significantly higher (p Ͻ 0.1) in soil samples from the rhizosphere of poplar trees than in adjacent agricultural soils, and atrazine degraders were found only in one rhizosphere sample. The relative abundance of these phenotypes (as a fraction of total heterotrophs) was not significantly different between rhizosphere and surrounding soils. Therefore, the poplar rhizosphere enhanced the growth of microbial populations that participate in natural bioremediation without exerting selective pressure for them.

1] We present a new statistical method to construct a model for the chemical composition of Earth's primitive mantle along with its variance. Earth's primitive mantle is located on the melting trend exhibited by the global compilation of mantle peridotites, using cosmochemical constraints on the relative abundances of refractory lithophile elements (RLE). This so-called pyrolite approach involves the least amount of assumptions, thereby being probably most satisfactory compared to other approaches. Its previous implementations, however, suffer from questionable statistical treatment of noisy geochemical data, leaving the uncertainty of model composition poorly quantified. In order to properly take into account how scatters in peridotite data affect this geochemical inference, we combine the following statistical techniques: (1) modeling a nonlinear melting trend in the multidimensional compositional space through the principal component analysis, (2) determining the primitive mantle composition on the melting trend by simultaneously imposing all of cosmochemical constraints with least squares, and (3) mapping scatters in original data into the variance of the final model through the bootstrap resampling technique. Whereas our model is similar to previous models in terms of Mg, Si, and Fe abundances, the RLE contents are at $2.16 ± 0.37 times the CI chondrite concentration, which is lower than most of previous estimates. The new model is depleted by >20% in a number of incompatible elements including heat-producing elements, U, Th, and K, and this depleted nature is further amplified (up to 60%) in terms of predicted composition for the present-day mantle.

The chemical structure of the milled-wood lignin isolated from Paulownia fortunei wood was investigated. The lignins were characterized by analytical pyrolysis and two-dimensional NMR that indicated a predominance of guaiacyl (G) over syringyl (S) units, and only showed small amounts of p-hydroxyphenyl (H) units, with a H:G:S molar ratio of 1:59:40. The heteronuclear single quantum correlation (HSQC) NMR spectrum gave additional information about the relative abundances of the different inter-unit linkages present in the lignin structure. Paulownia lignin showed a predominance of -O-4� aryl ether linkages (62% of total side-chains), followed by � resinol-type (12%) and -5 � phenylcoumaran-type structures (11%) and with lower amounts of other condensed structures such as spirodienone (3%) and dibenzodioxocin (2%) structures. The high lignin content (ca. 23% Klason lignin), together with the low S/G ratio and the abundance of condensed (carbon–carbon linked) structures (together with ...

A hailstorm in October 1994 was found to have moderately or severely impacted on 5.3% of the mangrove forests in Port Curtis. All mangrove species showed evidence of hail damage, including the three most common species (Rhizophora stylosa, Ceriops tagal and Avicennia marina). Physical effects of hail damage included stripping of leaves from plants, holes punched through leaves, bruising to bark, divots removed from bark, branch and plant death. Species-specific differences in vulnerability to the effects of hail were observed with C. tagal experiencing relatively higher mortality rates than the other two common mangrove species. A delayed pattern of mortality was observed in two species-C. tagal and A. marina. Alterations to mangrove community structure included: (1) reductions in stem density, stem diameter and basal area, (2) reductions in canopy cover (based on a photographic index of foliage projective cover) and (3) changes in relative abundance of species in mangrove zones. Recovery was observed in some stands but others had not recovered to pre-hail levels of canopy cover two years after the hailstorm. Recovery had occurred by regeneration of fresh leaves but no recruitment of young plants had been observed during the study. The forests in the impact area were dominated by either Ceriops tagal or Rhizophora stylosa with Avicennia marina as a subdominant in places. C. tagal dominated forests within the impact area were relatively more severely affected (41.8% in the severe category) than R. stylosa dominated communities (only 17.4% in the severe category). This indicated that C. tagal dominated forests were more vulnerable to the effects of hail damage than R. stylosa dominated forests. In addition, hail-impacted C. tagal dominated forests represented a relatively high percentage of the area of C. tagal dominated forests in Port Curtis (44.3%). This percentage was much higher than hail-impacted R. stylosa dominated forests in Port Curtis (2.7%). These two factors-relatively severe impact on C. tagal communities and a relatively higher percentage affected within the Port Curtis areaillustrate that hailstorms, as a form of natural disturbance, are an important influence on the forest ecology of mangrove ecosystems in this region.

Maps of current and potential vegetation spatial patterns can be used to assess land cover changes, and aid in ecosystem management and restoration. The vegetation spatial patterns of subalpine forest species are largely controlled by variation in temperature, water and solar radiation resources. These fundamental resources were quantified across a 1100-km 2 landscape using biophysical models, a digital elevation model (DEM), and weather station data. Field data of species abundances were used to define species-habitat relationships and calibrate maximum likelihood classifications of the biophysical gradients. For comparison, a standard land cover classification of Landsat Thematic Mapper satellite imagery had an overall accuracy 68.3%. Using the biophysical gradients alone gave a similar 67.4% accuracy. The highest accuracy classification (83.2%) used both biophysical and spectral data. The biophysical resources were also used to map the presence or absence of four herb and shrub species that cannot be sensed remotely. These predictions ranged from 60% to 79% accurate. Maps of relative abundance were less accurate, from 61% to 63.2%. This low result may be due to historical and stochastic events, or simply a small data set. The spatial pattern of species and communities that are controlled by resources can be predicted using general biophysical models. The species-habitat relationships can also be used to improve remote sensing products.

Anthropogenic alterations of nutrient inputs and food-web structure are two of the primary stressors affecting lake phytoplankton. This paper explores the independent and interactive effects of nutrients and food-web structure (as indexed by zooplankton size) on phytoplankton size structure by fitting time-series models to data from three lakes where both factors have been manipulated. I assessed phytoplankton size structure using three different approaches: small and large size classes, normalized size spectra, and average phytoplankton size. Increased phosphorus loading and increased zooplankton size had positive effects on large phytoplankton, slope of size spectra, and mean phytoplankton size, but negative effects on the relative abundance of small phytoplankton. The absolute abundance of small phytoplankton was increased by increased nutrients and decreased by increased zooplankton size. There was some evidence for nutrient ϫ zooplankton interactions, particularly from interlake comparisons which revealed that phytoplankton size structure responded to enrichment in qualitatively similar but quantitatively different ways in lakes with different food webs. Specifically, small phytoplankton increased more strongly with enrichment in lakes with many planktivores and few large zooplankton, while large phytoplankton increased more in lakes with few planktivores and many large zooplankton. Thus, food-web structure may influence the extent to which small vs. large phytoplankton respond to nutrient enrichment. Overall, size structure was an excellent descriptor of shifts in phytoplankton communities following manipulation of nutrient inputs and food-web structure. Size spectra and size classes were highly effective approaches for summarizing size structure; average phytoplankton size was somewhat less effective.

Pelecus cultratus (razor fish), a cyprinid fish, has become a dominant species in Neusiedler See. Gut content analyses of 400 specimens collected in 1989 and 1990 showed that Pelecus fed mainly on large zooplankton (Diaphanosoma, Leptodora and Arctodiaptomus), although their diet also included Insecta (larvae, pupae and adults) and Arachnida (spiders), occasionally small fishes. Comparison of the relative abundance of the zooplankton species in the stomach to the lake indicated that Pelecus strongly selected cladocerans over copepods, and fed mostly on large-sized individuals of Diaphanosoma, Leptodora and Arctodiaptomus. The fish showed a significant positive selectivity only for individuals of Diaphanosoma > 1.0 mm and Leptodora > 4.0 mm. In contrast, selectivity increased continuously in relation to the diameter of the compound eye of both prey species. This suggested that prey visibility was a key factor in determining the prey selectivity by Pelecus. It also seems likely that the persistence of the Leptodora population in Neusiedler See can be attributed to negligible predation pressure on the smaller sized individuals of this species.

Coral species composition of drilled cores from emergent bank reefs, and coral cover of the surface of old and living reefs located along the coast of the state of Bahia, Eastern Brazil, revealed that there is a marked change in the occurrence of the major building coral species in different time intervals of the reef structure, as well as in the living surface of reefs located in two different geographical sites. Holocene core sections from two reef areas (12°40 0 S-38°00 0 W and 18°00 0 S-39°00 0 W) have as major reef builders, on its topmost core interval (3 to 4 ky old), the endemic coral Mussismilia braziliensis Verrill, 1868, which also dominate on the 2.5-3.5 ky old surfaces of truncated reef tops. At the base of the cores (the 2 m lower interval, older than 4 ky BP), another endemic coral Mussismilia harttii Verrill, 1868 is the dominant reef component. The relative abundance of M. braziliensis on the living surfaces of shallow reefs from both areas, shows that in the southern area, it is up to 98% on reefs located 60 km off the coast, in depths between 3 and 4 m, but do not exceed 1.3% on the surface of the northern reefs located 1-2 km off the coast in depths 4-5 m. The Holocene falling sea level that occurred along the coast of Brazil since 5.1 ky BP, causes an increasing runoff into the area of coastal reefs. This phenomenon may have affected the nearshore reef building fauna, replacing a more susceptive coral fauna with one better adapted to low light levels and higher sediment influx. The high turbidity associated with early Holocene shelf flooding, should also be responsible for the absence of M. braziliensis during the initial stages of reef buildup in Brazil. At the present time, the rapidly increasing human pressure, due to changes in land uses of the coastal zone (increasing sedimentation rate, nutrification of coastal waters, industrial pollution) and underwater practices, such as overfishing and an intense tourism, is aggravating the recovery capacity of this already naturally threatened coral community. If this situation coupled with increasing sea surface temperature persists, modern coral reef growth, in Brazil cannot be maintained and the major reef building coral species of the reefs in Bahia, a remnant endemic coral fauna will very soon appear in the list of endangered species.

The Rimicaris exoculata dominates the megafauna of some of the Mid Atlantic ridge hydrothermal vent sites. This species harbors a rich community of bacterial epibionts inside its gill chamber. Literature data indicate that a single 16S rRNA phylotype dominates this epibiotic community, and is assumed to be a sulfide-oxidizing bacteria. However attempts of cultivation were not successful and did not allow to confirm it. The aim of our study was to test the hypothesis of sulfide oxidation in the gill chamber, by a multidisciplinary approach, using in vivo experiments at in situ pressure in the presence of sulfide, microscopic observations and a molecular survey. Morphology of microorganisms, before and after treatment, was analyzed to test the effect of sulfide depletion and re-exposure. Our observations, as well as molecular data indicate a wider diversity than previously described for this shrimp's epibiotic community. We observed occurrence of bacterial intracellular sulfur-and iron-enriched granules and some methanotrophic-like bacteria cells for the first time. Genes that are characteristic of methaneoxidizing (pmoA) and sulfide-oxidizing (APS) bacteria were identified. These results suggest that three metabolic types (iron, sulfide and methane oxidation) may co-occur within the epibiont community associated with Rimicaris exoculata. As this shrimp colonizes chemically contrasted environments, the relative abundance of each metabolic type could vary according to the local availability of reduced compounds.

Recently, the U.S. EPA issued the 303(d) list of impaired waters in Idaho State that contained the causes of impairment. This 303(d) list provides useful information that can be used to determine the Total Maximum Daily Loads (TMDLs). Implementation of TMDLs should result in pollutant reductions, which, in turn can lead to the restoration of these water bodies. Flow alteration is one of the potential sources of impairments in the Big Lost River in south-central Idaho, which have some negative impacts on the water quality and beneficial uses. Flow in the Big Lost River is altered, both in quantity and quality, and this reduces recreation activities, affects the fish assemblage, and changes the composition and relative abundance of aquatic species. The effect of riparian vegetation is another factor that needs to be predicted. In addition, three conservation schemes (construction of upstream reservoirs, downstream reservoirs, and canal linings) were proposed to restore flow in the downstream reaches of the river and compensate for water loss during the low flood seasons. However, there is no single predictive model that can be used to appropriately represent each of these issues as management decisions. In this paper, an expert system in the form of a Bayesian network, a graphical diagram of nodes and arcs, was implemented to examine all significant water management variables and relationships among these variables. Lining the irrigation canals was found to be the best scheme, followed by constructing an upstream reservoir. The TMDLs would benefit the water quality in the watershed but would not significantly increase the water quantity and solve the flow alteration problem. Consequently, this can be used to determine the sequence of decisions that can be taken in the future.

The effect of a topoclimatic gradient on soil nematode communities was investigated in the Israeli Judean Desert. Four locations along a 35 km gradient, from an elevation of 650 m above sea level with 620 mm rainfall to a –60 m relative to sea level with a rainfall below 110 m, were studied: Givat Yearim, Maale Adumim, Mishor Adumim and Kalia. Monthly soil samples were collected between January 1994 and December 1995. Thirteen nematode families and 17 genera were observed. Cephalobus, Heterocephalobus, Aphelenchoides, Tylenchus, Dorylaimus and Eudorylaimus were found to be the dominant genera. Ecological measurements of soil nematode community structure, diversity, and maturity indices were assessed, and comparisons between four locations and four seasons were made. Significant differences in the total numbers of nematodes were found between the locations (p < 0.01) and seasons (p < 0.05), where Givat Yearim > Maale Adumim > Mishor Adumim > Kalia, winter > spring > autumn > summer. Bacterivores were found to be the most abundant trophic group across locations and seasons, with a mean relative abundance of 55.0%. The densities of bacterivores, plant parasites and omnivores-predators during the winter season exhibited similar trends at all four locations, with Givat Yearim > Maale Adumim > Mishor Adumim > Kalia. None of the ecological indices were significantly different between locations. However, the maturity index (MI), trophic diversity (TD) and Simpson diversity (SI) exhibited significant differences between seasons.

Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as &#39;connectance&#39; or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size. Here we introduce two quantitative indices using interaction frequencies to describe the degree of specialization, based on information theory. The first measure (d&#39;) describes the degree of interaction specialization at the species level, while the second measure (H2&#39;) characterizes the degree of specialization or partitioning among two parties in the entire network. Both indices are mathematically related and derived from Shannon entropy. The species-level index d&#39; can be used to analyze variation within networks, while H2&#39; as a network-level index is useful for comparisons across different interaction webs. Ana...

Chemical analysis for Na, Cl, AI, Mn and V of surface snows and deeper ice core samples from station Milcent, Greenland, indicates a terrestrial or marine origin for these constituents. Pre-1900 enrichment factors, based on average crustal composition, are high for Zn and Hg and appear to be related to the volatility of these elements. A comparison of pre-1900 and 1971-1973 concentrations of V and Hg shows no decided increase due to industrial production, yet the relative abundance of Zn increased from 12 to 32 over this time period. The chemical composition of ancient ice is extremely useful in interpreting modern aerosols.

Floodplains are among the world's most threatened ecosystems due to the pervasiveness of dams, levee systems, and other modifications to rivers. Few unaltered floodplains remain where we may examine their dynamics over decadal time scales. Our study provides a detailed examination of landscape change over a 60-year period on the Nyack floodplain of the Middle Fork of the Flathead River, a free-flowing, gravel-bed river in northwest Montana, USA. We used historical aerial photographs and airborne and satellite imagery to delineate habitats (i.e., mature forest, regenerative forest, water, cobble) within the floodplain. We related changes in the distribution and size of these habitats to hydrologic disturbance and regional climate. Results show a relationship between changes in floodplain habitats and annual flood magnitude, as well as between hydrology and the cooling and warming phases of the Pacific Decadal Oscillation (PDO). Large magnitude floods and greater frequency of moderate floods were associated with the cooling phases of the PDO, resulting in a floodplain environment dominated by extensive restructuring and regeneration of floodplain habitats. Conversely, warming phases of the PDO corresponded with decreases in magnitude, duration, and frequency of critical flows, creating a floodplain environment dominated by late successional vegetation and low levels of physical restructuring. Over the 60-year time series, habitat change was widespread throughout the floodplain, though the relative abundances of the habitats did not change greatly. We conclude that the long-and short-term interactions of climate, floods, and plant succession produce a shifting habitat mosaic that is a fundamental attribute of natural floodplain ecosystems.

Background Ticks are regarded as the most relevant vectors of disease-causing pathogens in domestic and wild animals. The cattle tick, Rhipicephalus (Boophilus) microplus, hinders livestock production in tropical and subtropical parts of the world where it is endemic. Tick microbiomes remain largely unexplored. The objective of this study was to explore the R. microplus microbiome by applying the bacterial 16S tag-encoded FLX-titanium amplicon pyrosequencing (bTEFAP) technique to characterize its bacterial diversity. Pyrosequencing was performed on adult males and females, eggs, and gut and ovary tissues from adult females derived from samples of R. microplus collected during outbreaks in southern Texas. Results Raw data from bTEFAP were screened and trimmed based upon quality scores and binned into individual sample collections. Bacteria identified to the species level include Staphylococcus aureus, Staphylococcus chromogenes, Streptococcus dysgalactiae, Staphylococcus sciuri, Serr...

Fishery resources have declined and reef fish assemblages have changed over the last 30-40 years in the US Virgin Islands (USVI), even within a Marine Protected Area, Virgin Islands National Park (VINP). Groupers and snappers are now far less abundant, the proportion of herbivorous fishes has increased, individuals of many fish species are smaller, and spawning aggregations have been decimated. The national park is not a refuge for reef fishes. Relative abundance, species richness, and biomass of fishes in visual samples, and the species composition and number of fishes in traps are similar inside and outside VINP. Lobsters and conchs have decreased in abundance and/or size, and conch density is no greater within VINP than outside. Although habitat degradation has undoubtedly played a role, heavy fishing pressure has greatly contributed to the observed changes. No-take marine reserves, such as the recently established national monuments in the USVI, offer hope for recovery of fish assemblages and associated habitats.

Controversial arguments abound in the previous research on the relationship between R&D output and firm size, with these arguments implying the existence of a nonlinear relationship between the two. However, such a relationship has never been seriously examined. This study therefore aims to examine the nonlinear relationship between R&D productivity and firm size using a longitudinal dataset. In this article, the Taiwanese electronics industry is taken as the analytical sample since this industry has been viewed as the most R&D-intensive and prominent 'high-tech sector'. Another, more practical consideration for choosing this sector is the relative abundance of data available for variables for a longitudinal investigation.

Ana Silvaa,b, Laura Quintanaa, Matıas Galeanoa & Pablo Errandoneaa aDepartamento de Neurofisiologıa, Instituto de Investigaciones Biológicas Clemente Estable; Unidad Asociada de Facultad de Ciencias, Universidad de la República, Avda. Italia 3318, 11600 ...

Efforts to understand and preserve the seep communities of the deep Gulf of Mexico (GOM) begin with a comprehensive survey of the biodiversity of these communities. Previous studies have provided a conceptual model of the physiology, population, and community ecology of upper continental slope seeps. However, seeps at water depths below 1000 m in the Gulf of Mexico remain relatively unknown. In this study, data from 47 samples of tubeworm-and mussel-associated communities at depths of 1005-2750 m are examined. Other than tubeworms and mussels, 66 taxa of macro-and megafauna were collected, 43 of which appear to be restricted to water depths of over 1000 m, and 39 that have not been reported previously from the Gulf of Mexico. Diversity in mussel beds was highest at mid-slope depths, but tubeworm-associated communities did not show clear bathymetric trends in diversity. Diversity was higher in tubeworm aggregations at the alpha level (per sample), but higher in mussel beds at the beta level (species turnover among collections). Although both community types were often numerically dominated by the endemic shrimp Alvinocaris muricola, broad differences in the communities hosted by tubeworm aggregations and mussel beds were apparent. The most important factors explaining community similarity within community type were the depth, relative abundance of different mussel species in a bed, and the average size of tubeworms in an aggregation. The high proportion of deep-seep species that were found for the first time in the Gulf of Mexico emphasizes the importance of conservation efforts for these patchy communities.

Six Atlantic forest reserves, two large (c. 20,000 ha each), two medium-sized (c. 2,000 ha each) and two small (c. 200 ha each), located in northern EspõÂ rito Santo, south-eastern Brazil were censused for mammals from October 1994 to April 1996. Diurnal and nocturnal line-transect sampling was used for censusing mammals>1 kg body weight, and the relative abundance of species in the six fragments was compared. The number of mammal species recorded in the reserves was strongly related to the forest area, the richest community being recorded in the two large reserves and the poorest in the two small reserves. The large reserves had a structurally more complex community, with top predators, large, terrestrial frugivores and large myrmecophages. The mammal community of the small and the medium-sized reserves was impoverished and less complex. Frugivores were numerically predominant in both large and medium-sized reserves, whereas herbivores dominated the mammal community of the small reserves, mainly through the absence of agoutis Dasyprocta leporina and the high density of maned sloth Bradypus torquatus in the two small reserves. The lack of predators and the proliferation of secondary vegetation and lianas throughout the small reserves are probably the main causes for the success of arboreal folivores there. Illegal hunting was found to reduce the encounter rates of mostly large, terrestrial frugivores such as agoutis, pacas Agouti paca, peccaries Pecari tajacu and Tayassu pecari and deer Mazama spp., and is contributing to keep the population of the surviving species low. # 0006-3207/99/$Ðsee front matter # 1999 Elsevier Science Ltd. All rights reserved. P I I : S 0 0 0 6 -3 2 0 7 ( 9 8 ) 0 0 1 3 0 -X Biological Conservation 89 (1999) 71±82

Dryland degradation rarely translates into linear, declining trends in vegetation cover due to interannual climatic variability. Appropriate indicators of landcover modifications need to be defined for semi-arid regions. Our hypothesis is that degradation can be measured by: (1) a decrease in the resilience of vegetation to droughts; (2) a decrease in rain-use efficiency; and (3) a modification of floristic composition. The objective of this paper is to test the relationships between a remotely sensed indicator of vegetation, rainfall data and field measurements of biomass and floristic composition. The study was based on field measurements of vegetation conditions covering a period of 10 years, in the semi-arid region of the Ferlo in Senegal. Our results indicate that land-cover modifications in the Ferlo are best measured by changes in rain-use efficiency. No consistent trend in the relative abundance of grass species was visible at the scale of the decade, even on the two sites affected by degradation. Just after a drought, a given increase in rainfall results in less biomass production than is the case for normal years.

Mg-Al mixed oxides with Mg/Al molar ratios of 0.5-9.0 were obtained by thermal decomposition of precipitated hydrotalcite precursors. The effect of composition on structure and surface and catalytic properties was studied by combining several characterization methods with ethanol conversion reactions. The nature, density, and strength of surface basic sites depended on the Al content. On pure MgO, strong basic sites consisted predominantly of O 2− anions. Calcined hydrotalcites contained surface sites of low (OH − groups), medium (Mg-O pairs), and strong (O 2− anions) basicity. The relative abundance of low and medium strength basic sites increased with the Al content. The addition of small amounts of Al to MgO diminished drastically the density of surface basic sites because of a significant Al surface enrichment. Formation of surface amorphous AlO y structures in samples with low Al content (Mg/Al > 5) partially covered the Mg-O pairs and decreased the concentration of surface O 2− anions. At higher Al contents (5 > Mg/Al > 1), the basic site density increased because the Al 3+ cations within the MgO lattice created a defect in order to compensate the positive charge generated, and the adjacent oxygen anions became coordinatively unsaturated. In samples with Mg/Al < 1, segregation of bulk MgAl 2 O 4 spinels occurred and caused the basic site density to diminish. The catalyst activity and selectivity of Mg-Al mixed oxides in ethanol conversion reactions depended on composition. The dehydrogenation of ethanol to acetaldehyde and the aldol condensation to n-butanol both involved the initial surface ethoxide formation on a Lewis acid-strong base pair. Pure MgO exhibited poor activity because the predominant presence of isolated O 2− basic centers hindered formation of the ethoxide intermediate by ethanol dissociative adsorption.

Juvenile coral abundance and community composition depend on the spatial scale studied. To investigate this, an evaluation was made of juvenile coral density with hierarchical spatial analysis in the northern Mesoamerican Barrier Reef System (MBRS) at ~10 m depth. Study scope included semi-protected and unprotected areas located in this region. A total of 19 juvenile coral taxa were found, including 10 scleractinian species, 8 scleractinian coral genera not identified to species, and 1 Millepora species (Hydrozoa-Milleporidae). In terms of relative abundance, Agaricia spp., Siderastrea spp., and Porites spp. were the main juvenile taxa in the coral community at the surveyed sites, reefs, and regions levels. Greater variance was seen at smaller scales, at site level for taxa richness, and at the transect level for juvenile density, and lower variance was seen at larger scales (reefs and regions). The variance component contribution from each scale likely differed from other studies because of the different factors affecting the community and the different extensions of each scale used in each study. Densities (1–6.4 juvenile corals/m2) and dominant taxa found in this study agree with other studies from the Western Atlantic. Detected variability was explained by different causal agents, such as low grazing rates by herbivorous organisms, turbidity, and/or sediment suffocation and some nearby or distant localized disturbance (human settlement and a hurricane).

The aliphatic hydrocarbon fraction of an immature Monterey bitumen contains a high relative abundance of C&& A4, A$, A *(14) 5a-and AL4 Sa-sterenes, each having a very similar carbon number distribution. This is the first report of abundant A 8(14) Sa-and A" 5cu-sterenes in an immature sediment. The A4 and As sterenes appear to originate directly from A5 sterois. For the A8('4) SLY-and Ai4 %xsterenes we propose an origin from A' Sa-sterols which may be derived from a microbial transformation of A5 sterols. The presence of 5cu-and 5j%steranes in an unusual ratio of ca. 55:45 suggests the formation of a high abundance of 5Bstanols via the known microbial reduction pathway of A5 sterols.

Survey samplings on late summer phytoplankton communities were carried out on 48 high mountain lakes located on the Austrian and Italian slopes of the Eastern Alps. The lakes of North Tyrol (A) and South Tyrol (I) were sampled in 2000 as part of the EU project EMERGE (EVK1-CT-1999-00032). The lakes of Trentino (I) were investigated in other research projects during 1996 and 1997 (Adamello mountain range) and 2000 (catchment of the River Avisio), respectively. The objectives of this paper are: (1) to study taxonomy and biodiversity of Chrysophyceae, Dinophyceae and Cryptophyceae in high altitude lakes of the Eastern Alps; (2) to identify functional flagellate groups characterising lakes with similar habitat properties, (3) to identify the environmental variables driving abundance and distribution of the three selected algal groups, thus contributing to the selection of sensitive bioindicator taxa. The lakes investigated show rather wide morphological, chemical and trophic state gradients. Flagellate algae account for a median relative abundance (R.A.) of 68%. Chrysophyceae are the most important group in terms of biodiversity and R.A.. Special flagellate associations could be related to lake features, like catchment geology, mineralization level and nutrient concentrations. However, the distribution of flagellate algae did not allow a complete geographical separation of the lakes studied in the different districts. Multivariate canonical analyses indicate that the distribution of Chrysophyceae is mainly driven by NO 3 -N concentration and thermal conditions, while Dinophyceae are driven by a combination of alkalinity, altitude, thermal condition and, less importantly, nutrient concentration. Physical properties of the lakes, such as thermal condition and lake depth, represent the principal driving variables for Cryptophyceae. The responses to the different environmental variables suggest that the three flagellate groups analysed might be used as indicators for environmental changes in high mountain lakes of the Eastern Alps.

Valley Creek watershed, located in southeastern Pennsylvania, is a small, fourthorder stream that empties into the Schuylkill River at Valley Forge National Historic Park, thirty-five kilometers northwest of Philadelphia. The 64 km 2 watershed has been under extreme urbanization pressure over the past 30 years, resulting in rapidly increasing impervious surface cover and decreasing open space. The purpose of this study was to document some of the effects of urbanization on fish assemblages by quantifying the fish communities at fifteen sites throughout the watershed. Long-term effects of continued urbanization were identified, as data from the present study were compared to similar work completed nearly ten years earlier. There has been a shift in species composition from intolerant, coldwater species to more tolerant, eurythermal species. Currently, Valley Creek is supporting a naturally reproducing population of brown trout, but there has been a marked decline in relative abundance and range since 1993. Increased stream temperature from urban run-off is one of the primary issues in Valley Creek. Species composition was unique at each of the 15 stations owing to the effect of local land use in each station's drainage area. Fish assemblages revealed a patchy, non-continuous pattern of fish distribution.

The Upper Campanian Mishash Formation of southern Israel was deposited within the southern Tethys upwelling belt, with sea floors beneath this system characterized by poorly ventilated sediments approaching anoxia. This study was aimed at tracking the oxygen-poor gradient using benthic foraminiferal assemblages of organic-rich carbonates that are devoid of benthic macro-invertebrates and trace fossils.Quantitative data were gathered on foraminiferal faunas

The distributions of eight tricyclic and eight pentacyclic terpanes were determined for 2 16 crude oils located worldwide with subsequent simultaneous RQ-mode factor analysis and stepwise discriminate analysis for the purpose of predicting source rock features or depositional environments. Five categories of source rocks are evident: nearshore marine (i.e., paralic/deltaic); deeper-water marine; lacustrine; phosphaticrich source beds; and Ordovician age source rocks. The first two factors of the RQ-mode factor analysis describe 45 percent of the variation in the data set: the tricyclic terpanes appear to be twice as significant as pentacyclic terpanes in determining the variation among samples. J_acustrine oils are characterized by greater relative abundances of CzI diterpane and gammacerane; nearshore marine sources by Cl9 and CrO diterpanes and oleanane; deeper-water marine facies by Cr4 and CrJ tricyclic and C,, plus Cr2 extended hopanes; and Ordovician age oils by Cr, and Crs pentacyclic terpanes. Although thermal maturity trends can be observed in factor space, the trends do not necessarily obscure the source rock interpretations. Also, since bacterial degradation of crude oils rarely affects tricyclic terpanes, biodegraded oils can be used in predicting source rock features. The precision to which source rock depositional environments are determined might be increased with the addition of other biomarker (e.g., steranes) and stable isotope data using multivariate statistical techniques.

Glucosinolate levels in leaves were determined in a collection of 113 varieties of turnip greens (Brassica rapa L.) from northwestern Spain grown at two sites. Sensorial attributes were also assessed by a consumer panel. The objectives were to determine the diversity among varieties in total glucosinolate content and glucosinolate profile and to evaluate their sensory attributes in relation to glucosinolate content for breeding purposes. Sixteen glucosinolates were identified, being the aliphatic glucosinolates, gluconapin and glucobrassicanapin the most abundant. Other aliphatic glucosinolates, such as progoitrin, glucoalyssin, and gluconapoleiferin were relatively abundant in varieties with a different glucosinolate profile. Indolic and aromatic glucosinolate concentrations were low and showed few differences among varieties. Differences in total glucosinolate content, glucosinolate profile and bitterness were found among varieties, with a total glucosinolate content ranging from 11.8 to 74.0 lmol g À1 dw at one site and from 7.5 to 56.9 lmol g À1 dw at the other site. Sensory analysis comparing bitterness with variation in glucosinolate, gluconapin and glucobrassicanapin concentrations suggested that these compounds and their breakdown products are not the only determinants of the characteristic flavour of this vegetable. Other phytochemicals are probably involved on the characteristic bitter flavour. The varieties MBG-BRS0132, MBG-BRS0082, MBG-BRS0173, and MBG-BRS0184 could be good candidates for future breeding programs since they had high total glucosinolate content and good agronomic performance. The presence of glucoraphanin in some varieties should be studied more extensively, because this aliphatic glucosinolate is the precursor of sulforaphane, a potent anti-cancer isothiocyanate.

Dissolved organic matter (DOM) in sediment pore water is a complex molecular mixture reflecting various sources and biogeochemical processes. In order to constrain those sources and processes, molecular variations of pore water DOM in surface sediments from the NW Iberian shelf were analyzed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and compared to river and marine water column DOM. Weighted average molecular element ratios of oxygen to carbon ((O/C) wa ) and hydrogen to carbon ((H/C) wa ) provided general information about DOM sources. DOM in local rivers was more oxygenated ((O/C) wa 0.52) and contained less hydrogen ((H/C) wa 1.15) than marine pore water DOM (mean (O/C) wa 0.50, mean (H/C) wa 1.26). The relative abundance of specific compound groups, such as highly oxygenated aromatic compounds or nitrogen-bearing compounds with low H/C ratios, correspond to a high concentration of lignin phenols (160 lg/g sediment dry weight) and a high TOC/TN ratio (13.3) in the sedimentary organic matter and were therefore assigned to terrestrial sources. The lower degree of unsaturation and a higher relative abundance of nitrogen-bearing compounds in the pore water DOM reflected microbial activity within the sediment. One sampling site on the shelf with a high sediment accumulation, and a humic-rich river sample showed a wide range of sulfur compounds in the DOM, accompanied by a higher abundance of lipid biomarkers for sulfate-reducing bacteria, probably indicating early diagenetic sulfurization of organic matter.

Apple cv. 'Jonagold' fruit were picked in three different regions of Belgium. In each region one organic and one integrated orchard with identical climatic and soil characteristics was sampled. Fruit were stored in air and under CA conditions (1% O 2 , 2.5% CO 2 ) at 1 • C for 6 months. The acoustic stiffness, firmness, soluble solids contents, acid and sugar contents, and the aroma profile were measured. Quality parameters were analysed right after harvest and storage. At both times an additional shelf-life experiment was carried out to simulate the conditions in the commercial chain.

The effectiveness of semiquantitative pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) as a rapid analytical technique for sourcing continental organic matter (OM) in marine sediments was examined by comparison with classical GC-MS analyses of solvent extractable lipid markers. Py-GC-MS was directly applied to HCl/HF de-ashed surface sediment samples collected in five stations located in north western Adriatic Sea. The resulting pyrolysates were characterised by compounds indicative of different biological precursors (e.g. proteins, carbohydrates, chlorophylls), including lignin methoxyphenols diagnostic for continental inputs. The relative abundance of pyrolytic markers was compared to the distribution of n-alkanes, n-alkanols and sterols extracted from the same sediments and determined by GC-MS analyses. For each class of molecular indicators, the terrigenous to aquatic ratio (TAR) was determined as follows: relative abundance of methoxyphenol/protein markers (TAR PY ), concentration ratios of (C27 + C29 + C31)/(C15 + C17 + C19) n-alkanes (TAR HC ), (C26 + C28+ C30)/(C14 + C16) n-alkanols (TAR AL ) and sitosterol/cholesterol (TAR ST ). A positive correlation was found between TAR PY and both TAR HC and TAR AL indicating a decreasing contribution of land-plant-derived materials seaward in two investigated transects. TAR ST values displayed a different trend suggesting a mixed origin for sitosterol. The distribution of TAR PY values was also in good agreement with that of atomic C/N ratios. Considering the complexity of environmental systems (diagenetic alteration, different fractions of OM analysed) the obtained results indicate that the pyrolytic marker approach by Py-GC-MS is valuable for sourcing marine OM on a semiquantitative base, providing data consistent with GC-MS determinations of lipid markers and elemental bulk analyses.

The coccolithophore assemblages in two ODP Sites (1237 and 1238) are studied in order to reconstruct the paleoenvironmental conditions in the tropical and equatorial Pacific during the last 800 kyr. Both ODP Sites are located in the two most significant upwelling zones of the tropical and equatorial Pacific: Peru and Equatorial upwelling, respectively. The two sites are considered to have had similar evolutions. The coccolith relative abundance, the nannofossil accumulation rate (NAR) and the N ratio (namely, the proportion of < 3 mm placoliths in relation to Florisphaera profunda) allow us to identify three different intervals. Interval I (0.86-0.45 Ma) and interval III (0.22-0 Ma) are related to weak upwelling and weak Trade Winds, as suggested by coccolithophore assemblages with low N ratios. Interval II (0.45-0.22 Ma), characterized by dominant Gephyrocapsa caribbeanica and very abundant ''small'' Gephyrocapsa and Gephyrocapsa oceanica, is conversely related to intense upwelling and enhanced Trade Winds. # Résumé Les assemblages de coccolithophoridés de deux sites ODP (1237 et 1238) sont étudiés, dans le but de reconstruire les conditions paléoenvironnementales dans le Pacifique tropical et équatorial pendant les derniers 800 ka. Les deux sites ODP sont liés aux deux plus importantes zones d'upwelling, du Pacifique tropical et équatorial : les upwellings du Pérou et Équatorial. Les deux sites présentent une évolution similaire. L'abondance relative des coccolithes, le taux d'accumulation des nannofossiles calcaires et le rapport N (proportion des placolithes de taille inférieure à 3 mm par rapport à Florisphaera profunda) nous ont permis d'identifier trois intervalles différents. L'intervalle I (0,86-0,45 Ma) et l'intervalle III (0,22-0 Ma) correspondent à une faible intensité de l'upwelling ainsi que des Alizés. En effet, ces deux intervalles présentent des assemblages de coccolithophoridés similaires, à rapport N faible. L'intervalle II (0,45-0,22 Ma), caractérisé par la dominance de Gephyrocapsa caribbeanica et de très abondants « petits » Gephyrocapsa et Gephyrocapsa oceanica, est en revanche mis en relation avec des conditions d'upwelling et d'Alizés intenses. # 2009 Elsevier Masson SAS. Tous droits réservés.