Equidistant Stations Research Articles

Automated Seismo-Volcanic Event Detection Applied to Stromboli (Italy)

Many active volcanoes exhibit Strombolian activity, which is typically characterized by relatively frequent mild volcanic explosions and also by rare and much more destructive major explosions and paroxysms. Detailed analyses of past major and minor events can help to understand the eruptive behavior of volcanoes and the underlying physical and chemical processes. Catalogs of these eruptions and, specifically, seismo-volcanic events may be generated using continuous seismic recordings at stations in the proximity of volcanoes. However, in many cases, the analysis of the recordings relies heavily on the manual picking of events by human experts. Recently developed Machine Learning-based approaches require large training data sets which may not be available a priori. Here, we propose an alternative user-friendly, time-saving, automated approach labelled as: the Adaptive-Window Volcanic Event Selection Analysis Module (AWESAM). This strategy of creating seismo-volcanic event catalogs consists of three main steps: 1) identification of potential volcanic events based on squared ground-velocity amplitudes, an adaptive MaxFilter, and a prominence threshold. 2) catalog consolidation by comparing and verifying the initial detections based on recordings from two different seismic stations. 3) identification and exclusion of signals from regional tectonic earthquakes. The strength of the python package is the reliable detection of very small and frequent events as well as major explosions and paroxysms. Here, it is applied to publicly accessible continuous seismic recordings from two almost equidistant stations at Stromboli volcano in Italy. We tested AWESAM by comparison with a hand-picked catalog and found that around 95% of the seismo-volcanic events with a signal-to-noise ratio above three are detected. In a first application, we derive a new amplitude-frequency relationship from over 290.000 seismo-volcanic events at Stromboli during 2019–2020 which were detected by AWESAM. The module allows for a straightforward generalization and application to other volcanoes with frequent Strombolian activity worldwide. Furthermore, this module can be implemented for volcanoes with rarer explosions.

Early Life Stages of Fishes in Lake Taal, Philippines: Assessment and Implications for Biodiversity Management and Conservation

Lake Taal is the third largest lake in the Philippines and its fisheries provide livelihood to thousands of locals in its coastal areas. This study was conducted to recommend possible strategies and measures to conserve and protect the population of fishes, especially of the early life stages (ELS). The composition, abundance, and distribution of ELS and the environmental factors affecting these were investigated through monthly ichthyoplankton surveys and monitoring of water parameters, phytoplankton, and zooplankton abundances in 12 equidistant stations from January 2015 to December 2018. A total of 26,345 fish eggs and 9,140 fish larvae were collected, of which 88.9% of the fish larvae were morphologically identified into eight families, while the rest were unidentified. Families Terapontidae (44.5%) and Gobiidae (37.0%) numerically dominated the identified larvae catch. Distribution of the egg, yolk sac, and pre-flexion stages (ELS) significantly varied across stations. Three stations on the northern basin of the lake showed the highest fish egg abundance (731.82, 246.47, and 381.28 ind 100 m–3) while stations on the west, northwest, and eastern bay of the lake showed the highest abundance of fish larvae (153.76, 121.28, and 94.64 ind 100 m–3). The temporal distribution of ELS was highly associated with zooplankton, green algae, and salinity while spatial distribution was highly associated with the majority of the water parameters and chlorophyll a. Seasonal and annual distribution of ELS showed significant variation, which reveals possible spawning patterns of the identified fish larvae and the influence of varying environmental conditions to the distribution of ELS. Based on these, the identified possible spawning and larval foraging grounds are recommended as protected zones. Reduction of nutrient inputs to minimize changes in the lake trophic condition is also recommended.

Calcium distribution in the subtropical Atlantic Ocean: Implications for calcium excess and saturation horizons

This study constituted the first attempt to measure dissolved calcium ([Ca2+]meas) in the subtropical North Atlantic, during a zonal transoceanic cruise along 24.5°N (WOCE A05 section), in summer 1992. [Ca2+]meas was obtained in 20 full-depth equidistant stations along the section, showing that their gradients are rather sensitive to horizontal and vertical water mass distribution. Deep waters along 24.5°N systematically show a positive calcium excess of 20±14μmol·kg−1, i.e., more [Ca2+] than expected by CaCO3 dissolution and organic matter oxidation (estimated by total alkalinity and nitrate). CaCO3 settling and benthic dissolution accounts for 70% and the North Atlantic plus Arctic riverine inputs of HCO3− for the remaining 30%. Combining [Ca2+]meas and CO2 data sets, carbonate mineral saturation states distributions for aragonite and calcite can be obtained. The two solubility ratios resulted, on average, 0.5% smaller than if conservative behavior for Ca2+ was assumed (an approach widely followed when [Ca2+]meas is unknown). As a result, shallower saturation horizon depths for both carbonate states (19 dbar for aragonite and 10 dbar for calcite) are yielded if [Ca2+]meas is taken into account instead than estimated from salinity.

Concentracion de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y sedimentos de una playa artificial, en la bahia San Jorge 23ºS, norte de Chile

It was evaluated the heavy metal content (Cu, Ni, Zn, Cd, Pb) in biota and sediment of an artificial beach (Paraiso) and a natural beach (El Lenguado), both located in San Jorge bay, northern Chile. The results were used to compare both systems, the degree of fulfillment of national and international environmental regulations, and the effect of the construction of the artificial beach on the level of metal contamination historically existing in that area. Equidistant stations were located at each beach in which the organisms were extracted, that ranged from the intertidal to the subtidal. Sediment samples were taken at each beach and slopes were determined with the Emery method. The granulometric analysis evidenced the predominance of medium sand in El Lenguado beach, and medium and fine sand in Paraiso beach. The organic matter content was greater in El Lenguado. In Paraiso beach were determined 5 phylum/superclass, grouped in 19 taxa, while in El Lenguado were found 4 phylum/superclass grouped in 22 taxa. The metal content in sediments and in the majority of organisms shows higher values in Paraiso beach. This results along with the Chilean and American quality norms suggest an evident deterioration of the environmental quality of Paraiso beach, which is demonstrated by an increase in the concentrations of these metals from its construction, which exceed the established limits by both norms.

Heavy metals concentration (Cu, Ni, Zn, Cd, Pb), in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

It was evaluated the heavy metal content (Cu, Ni, Zn, Cd, Pb) in biota and sediment of an artificial beach (Paraiso) and a natural beach (El Lenguado), both located in San Jorge bay, northern Chile. The results were used to compare both systems, the degree of fulfillment of national and international environmental regulations, and the effect of the construction of the artificial beach on the level of metal contamination historically existing in that area. Equidistant stations were located at each beach in which the organisms were extracted, that ranged from the intertidal to the subtidal. Sediment samples were taken at each beach and slopes were determined with the Emery method. The granulometric analysis evidenced the predominance of medium sand in El Lenguado beach, and medium and fine sand in Paraiso beach. The organic matter content was greater in El Lenguado. In Paraiso beach were determined 5 phylum/superclass, grouped in 19 taxa, while in El Lenguado were found 4 phylum/superclass grouped in 22 taxa. The metal content in sediments and in the majority of organisms shows higher values in Paraiso beach. This results along with the Chilean and American quality norms suggest an evident deterioration of the environmental quality of Paraiso beach, which is demonstrated by an increase in the concentrations of these metals from its construction, which exceed the established limits by both norms.

Distribution pattern of Anomalocardia brasiliana Gmelin, 1971 (Mollusca, Bivalvia) in a tropical coastal ecosystem

Anomalocardia brasiliana (Gmelin, 1791) (Bivalvia, Veneridae) distribution pattern was studied from September 2006 to June 2007 in the Itamaracá tropical estuarine system in Northeastern Brazil. Three areas were selected and in each one three transects with three equidistant stations were plotted. At each station, four samples were collected with a 0.0626 m2 quadrate. Shell morphometric measurements showed the presence of four size classes, varying from <10 to >20 mm. A total of 56,865 individuals of A. brasiliana were collected and the three banks studied showed significant differences in abundance (Kruskal-Wallis-Dunn p< 0.05). Ramalho area presented 49% of the total collected individuals and the size class 11 to 15 mm predominated in all sites. Key words: Bivalve mollusk; Anomalocardia brasiliana; Distribution pattern.

Circulation and horizontal fluxes in the northern Adriatic Sea in the period June 1999–July 2002. Part I: Geostrophic circulation and current measurement

The dramatic increase in the occurrence of massive mucilage events in the northern Adriatic (NA) since their recent conspicuous reappearance in the late 1980s prompted a study of circulation and horizontal fluxes. Three transects with equidistant stations (10 km) were thus monitored monthly between June 1999 and July 2002. The geostrophic method was used to compute currents across the three transects from the CTD data, and dynamic heights provided a picture of the horizontal surface circulation. Currentmeter data records were used to adjust the reference surface and to validate the results for the southernmost and deeper (up to 70 m) transect (Senigallia–Susak Island). Geostrophic currents allowed estimation of monthly water fluxes across the transect. Different circulation regimes in the NA were observed, which may have affected mucilage events. When mucilage was absent (1999) or reduced (2001) in the western sector, the Western Adriatic Current (WAC, carrying water out of the NA) was found to be active, whilst the WAC was very weak or reversed when massive mucilage events occurred (2000 and 2002). Opposite behaviour has been observed for the Istrian Coastal Counter-Current (ICCC, retaining freshwater water in the NA) which was more intense during or after massive mucilage events and did not appear when mucilage was absent. Both WAC weakening and ICCC strengthening indicate a longer residence time of riverine waters in the NA, which favours mucilage development. Conclusively, WAC and ICCC result as key elements in controlling massive mucilage phenomena in the NA.

Mantle control of plate boundary deformation

The seismic wavefield propagating along the recently instrumented Pacific‐North American plate boundary (California) displays remarkable variation, with regional shear waves arriving at coastal stations up to 20 seconds earlier than equidistant stations in eastern California. Broadband modeling of this data reveals that coastal paths sample fast upper mantle typical of Miocene‐aged ocean plate (>50 Km thickness). Inland paths sample slower uppermost mantle, with the seismic lithosphere, or lid, measuring less than 5 Km thick, characteristic of the Basin and Range extensional province. The boundary in the uppermost mantle between these provinces is sharp, expressing the juxtaposition of the stronger Pacific plate with weaker continental North America. The lid step coincides with regionally maximum dextral strain rates measured with GPS, suggesting the uppermost mantle modulates long term, regional‐scale continental margin deformation and evolution.

Distribution of Jasus spp. (Decapoda:Palinuridae) phyllosomas in southern waters:implications for larval recruitment

We sampled the distribution of mid- and late-stage (= advanced) Jasus group 'lalandii' rock lobster phyllosomas at 28 approximately equidistant stations across similar to 16 000 km of ocean between the west coast of Africa and the west coast of New Zealand to determine whether the larvae were mostly associated with the patchy allopatric distribution of the adults or were widespread. The Jasus phyllosomas (n = 210) occurred in greatest abundance in the general vicinity of adults. Nucleotide-sequencing and restriction-fragment length polymorphism (RFLP) techniques were used to identify 93 of these larvae from 18 stations to species level. Most of the larvae caught were J. lalandii and J, edwardsii, and a few were probably J. paulensis. Most of these larvae were taken near (within a few hundred kilometres) their respective adult habitat off southern Africa, Australia and New Zealand, and Amsterdam Island. The exceptions were small numbers of J. lalandii larvae in the southwest Indian Ocean as far east as Amsterdam Island, adjacent to the J. paulensis habitat, and J. edwardsii larvae across the south Tasman Sea. A single larva off southwest Africa could not be identified to any known Jasus species and may indicate the presence in the genus of an as yet undiscovered species or subspecies. No J. caveorum, J. frontalis, or J. verreauxi (and probably no J. tristani) were found. Our results suggest that Jasus spp. larvae which subsequently recruit to benthic populations use behavioural strategies and/or physical mechanisms to avoid being carried too far away from their parental ground. However, a proportion of larvae, small yet possibly not insignificant, occurs great distances from where adults of the species are known. These larvae are unlikely to recruit to benthic populations, but their occurrence invites further consideration of how Jasus spp. maintain allopatric populations.

Measurement strategy of PRISMA:design and realisation

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 156:245-254 (1997) - doi:10.3354/meps156245 Measurement strategy of PRISMA: design and realisation Uwe H. Brockmann1,*, Thomas Raabe1, Klaus Nagel2, Michael Haarich3 1Zentrum für Meeres- und Klimaforschung der Universität Hamburg, Institut für Biogeochemie und Meereschemie, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany 2Institut für Ostseeforschung an der Universität Rostock, Seestr. 15, D-18119 Rostock-Warnemünde, Germany 3Bundesforschungsanstalt für Fischerei, Wüstland 2, D-22589 Hamburg, Germany *E-mail: brockmann@rrz.uni-hamburg.de To approach the aims of the German research project PRISMA, an integrated measurement strategy was developed, following the nesting principle: (i) drift experiments which involved sampling in a defined water mass aiming at the analyses of transfer and transformation processes were supplemented by (ii) analyses at 3 equidistant drifting positions 3 n.m. (nautical miles) apart, which were performed in (iii) a grid of equidistant stations at fixed positions 10 n.m. apart, covering the German Bight, to identify hydrodynamic and biogeochemical changes or interferences affecting the drift area. In this way, the spatial representativeness of frequent point measurements at drifting stations could be estimated, as well as the short-term variability during the 4 d duration of each grid survey in the German Bight. The latter also provided data sets for transport modelling. In addition time series data were collected at 6 mooring stations equipped with current meters, CTD and transmission meters. Some of the modelling was already performed during the experiment with a daily operational model (used by BSH, Bundesamt für Seeschiffahrt und Hydrographie, Hamburg) comprising atmospheric and ocean models. The output provided nearly real-time information on the drift direction of the defined water masses. The results of more extensive model calculations allowed the subsequent description of water mass transports in different depths of the German Bight. A great number of samples were taken for the estimation of bulk parameters in order to define the status of the ecosystem. Taking account of the time and position of these measurements, selected samples were processed for the analysis of contaminants, which required more effort. Some examples are discussed that illustrate the advantages and disadvantages of the measurement strategy. These focus mainly on hydrographic measurements and nutrient data, reflecting the dominant biological processes investigated during PRISMA. Measurement strategy · Drift experiment · Nitrate Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 156. Publication date: September 25, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Feeding responses by adult males ofMelanoplus sanguinipes(Fabricius) to carbohydrates and amino acids

Adult males of Melanoplus sanguinipes (Fabricius), the migratory grasshopper, were starved for 18 h and were placed, one per arena, into arenas containing treated glass-fibre discs. The discs had been dipped into aqueous solutions of carbohydrates or amino acids of 0.0001, 0.001, 0.01, or 0.1 M concentration and allowed to dry at air temperature. They were placed vertically on pins and distributed at random among five equidistant stations around the periphery of the bottom of the arena. Each arena was provided with a glass-fibre disc that had been dipped in distilled water, as a control. The grasshoppers were allowed to feed at room temperature at 16:8 (L:D) for 24 h. Determinations of the effects of nutrient chemicals on feeding were determined by dry-weight differences between the weights of the treated discs before and after testing. Ribose, glucose, mannose and trehalose had no influence on feeding; 0.01 M fructose of 0.1 M arabinose, galactose, melibiose or sucrose increased feeding over that obtained with the control discs (P = 0.05); and 0.01 M xylose or sorbose depressed feeding. Each of the 11 amino acids investigated was phagodeterrent to adult males of M. sanguinipes. The present results confirm the variability of responses to carbohydrates among acridids; however, the reversal of phagodeterrency of sorbose or xylose at 0.1 M concentration is believed to be the first reported instance of such behaviour. In contrast to other reports of phagostimulation of acridids by individual amino acids or amino-acid mixtures, all protein amino acids tested in the present study were phagodeterrent to adult males of M. sanguinipes, even at low concentrations.

Rachman and Hodgson (1974) a decade later: How do desynchronous response systems relate to the treatment of agoraphobia?

The patterning of subjective anxiety and measured heart rate (HR) was examined for 28 agoraphobics who participated in a standard 12-week treatment program at the Center for Stress and Anxiety Disorders. Twenty-eight agoraphobics attempted a walk (22 pre-, mid-, post-treatment; 6 pre, post) along a course that began at this clinic and ran for 1 mile into an increasingly crowded (and therefore more frightening) section of the city. The course consisted of 20 approximately equidistant stations at which S's HR was measured and subjective anxiety (SUDS) recorded. Results indicate that overall improvements in mean HR and SUDS do occur as a function of treatment. Further analysis targeted at examining the utility of synchrony and relative HR level as predictors of response were conducted at post-test. Data indicated that synchrony between HR and SUDS demonstrated utility as a descriptor of psychophysiological changes during treatment but did not predict treatment success. Only relative HR level achieved significance as a predictor of treatment outcome at post-test. That is, patients who began with the highest levels of physiological responsiveness to the behavioral walk were most likely to evidence improvement on a composite measure. Discussion focuses on the potential implications of these findings for clinical research and practice.

Condensation Film Coefficients for Mixtures of Isobutane and Isopentane

Presented herein are data on heat-transfer film coefficients for the condensation of 90/10, 80/20, 70/30, 60/40, and 50/50 mole-% isobutane/isopentane. For comparison, data on condensation of instrument-grade and commercial-grade isobutane are also presented. The vapor was condensed on the outside of a horizontal instrumented tube with cooling water flowing inside the tube. The tube was fitted with thermocouples imbedded inside the wall of the tube to measure tube wall temperature at five equidistant stations along the length of the tube. The vapor temperature in the shell was measured using 17 thermocouples located at 150 mm intervals and spanning the five stations. Results for the data taken, based on the difference between vapor temperature and wall temperature, indicate lower condensation film coefficient when the mole fraction of isopentane is increased in the mixture. Mole-percent values of isopentane <50% would be expected to reverse this trend.

Changes in Interstitial Water Salinity of a Mississippi Tidal Marsh

The salinity of interstitial water (i.e., the salinity of the free soil water) was examined at 11 equidistant stations along a transect on a Mississippi tidal marsh dominated byJuncus roemerianus andSpartina cynosuroides. Changes in the nearby surface water (e.g., bay water) were reflected in the changes in interstitial water salinity. The salinity of interstitial water was usually higher, varying between 2.5 and 15.8‰ from February 1975 through January 1976, than the salinity of the nearby surface water which ranged from 0.0 to 11.5‰. Following a long period of high salinity in the bay and sound (exceeding 14‰), the salinity of the interstitial water increased to a maximum of 16.8‰ in October. The salinity increased as the distance of the sampling station from the source of the flood water increased. Mean interstitial wate salinity across the marsh studied was within 10‰ which did not seem to influence the marsh plant zonation occurring on the marsh.