1,265 research outputs found
Updating the bathymetry of the Maltese Islands : a national-scale marine survey employing interferometric sonar
Chapter 8The ERDF project detailed a requirment for the scanning of an extensive area of 415
square kilometers employing an interferometric sonar. The process, though hampered
by high wind and adverse sea conditions was completed as per contract requirements,
yielding interesting new information of the bathymetric landscapes of the Maltese Islands.
Survey design: The campaign for the bathymetric survey of the Maltese islands, carried
out during the summers of 2012 and 2013, summed total area of about 415 square
kilometres and covered depths between 15 and 200 m. Th e total survey area was divided
into 28 survey blocks, laid out so each one was completed during a full day of work. This
rule applied to all the blocks except for blocks 16 and 17 which were completed over
the course of two days each. Each survey block was completed by running survey lines
parallel to the blocks’ longitudinal axis. During rough weather, lines were run parallel to
predominant wave direction to minimise vessel roll. Line spacing ranged from 50 to 300
metres and was decided by a combination of the sensor’s accuracy at increasing horizontal
range, depth, seabed type and sea state. Crosslines were also run for each block, usually on
the boundary, to allow for additional data checks between neighbouring blockspeer-reviewe
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Procinura, P. aemula
Number of Pages: 4Integrative BiologyGeological Science
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Acoustic Characteristics of Word-Final American English Liquids Produced by L2 Adult Speakers
In this study, the acoustic differences between native English speakers’ (L1) and native-Korean speakers’ (L2) production of American English liquids /ɹ/, /l/ and /ɹl/ were examined among 14 Korean speakers and 13 English speakers. Temporal measures included (1) relative timing of maximum constriction and (2) duration of vocalic nuclei. Spectral measures included (1) Euclidean distance between /ɹ/ and /l/ and (2) frequency difference between F2 and F3. The results indicated a significant interaction between speaker group and phonetic stimuli. That is, L2 speakers produced a similar degree of constriction across semivowels, whereas L1 speakers produced varying degrees of F2-F3 constrictions across phonetic stimuli. In addition, the relative timing of maximum constriction occurred earliest in /ɹl/ and latest in /ɹ/ production for L1 speakers. The opposite pattern was observed for L2 speakers. Furthermore, the two speaker groups exhibited significantly different results concerning the Euclidean distances between /ɹ/ and /l/. The Euclidean distances between the two sounds were significantly closer for L2 speakers compared to L1 speakers which indicates reduced acoustic distinction between the two liquids in L2 speakers. The same results were revealed for both measurement points, temporal midpoint and maximum constriction point. However, the speaker group difference was more apparent when measured from the point of maximum F2-F3 constriction compared to the temporal midpoint. The findings provide acoustic data on liquid production in L2 speakers and support the use of these measures in a clinical setting
A conservation checklist of the amphibians and reptiles of Mexico City, with comparisons with adjoining states
Mexico City houses one of the most populous urban areas of the world, and the modification of its natural habitat likely influences the biological diversity found there. In particular, amphibians and reptiles are likely affected by these modifications. Herein, we present an updated list of the species of amphibians and reptiles that inhabit Mexico City. Mexico City harbors 65 species of amphibians and reptiles, which represent 21 families and 33 genera. These include 18 species of amphibians (nine anurans and nine salamanders) and 47 species of reptiles (14 lizards, 30 snakes [one introduced], and three turtles [one introduced]). Forty-eight of the amphibian and reptile species in Mexico City are endemic to Mexico, with two endemic to Mexico City. The most diverse region of Mexico City is the Forests and Ravines region, which is home to 43 species. Eleven species of amphibians and reptiles in Mexico City are IUCN listed, 16 are placed in a protected category by SEMARNAT (Secretaria del Medio Ambiente y Recursos Naturales), and 27 species are categorized as high risk by the EVS (Environmental Viability Score). Mexico City shares almost 94% of its species with the State of Mexico
An analysis of the inter-state similarity of the herpetofaunas of Mexican states
Mexico is a megadiverse country with high amphibian and reptile richness. Understanding how Mexico's herpetofauna is shared among Mexican states can contribute to developing conservation plans by figuring out which states may need to coordinate conservation actions. We generated species lists for the herpetofauna for all Mexican states, and used hierarchical clustering analyses to identify clusters of states on the basis of amphibian and reptile species separately. We also calculated pair-wise Jaccard distances for all Mexican states for amphibians, reptiles, and physiographic provinces and estimated the length of shared borders between states and the geographic (straight-line) distance between the centroids of pairs of states. We used these data to explore potential drivers of the cluster analysis results. Our cluster analysis for amphibians identified five clusters with nine subclusters, and for reptiles, resulted in four clusters with six subclusters. In general, the clusters for Mexican amphibians and reptiles have a similar composition of states. However, for amphibians, the states of Veracruz and Puebla form a cluster separate from a large cluster of northeastern Mexican states, whereas in reptiles Veracruz and Puebla cluster with northeastern Mexican states. Jaccard distances of amphibians and reptiles were highly, positively correlated. Both amphibian and reptile Jaccard distances were positively correlated with the physiographic provinces' Jaccard distance and shared border length and negatively correlated with the distance between centroids. Taken together, our results suggest that the pattern of the sharing of herpetofaunal species among Mexican states is a consequence of the states' proximity. Such a pattern is consistent with the underlying driver being the similarity of physiographic provinces (i.e., habitats and ecosystems) of these states (i.e., geographic proximity likely reflects, at least in large part, ecological similarity). Our results suggest clusters of states that should coordinate the conservation and management of their herpetofaunas. For example, clusters of states in southern Mexico share a high number of threatened amphibian species and clusters of states in northern Mexico share a high number of threatened reptile species. Oaxaca is also a state that has a unique herpetofauna and a high number of threatened species of both amphibians and reptiles
A conservation checklist of the herpetofauna of Morelos, with comparisons with adjoining states
Despite being one of the smallest states in Mexico, the high diversity of habitats in Morelos has led to the development of a rich biota made up of a mixture of species typical of the Neovolcanic Axis and the Sierra Madre del Sur. However, recent expansion of cities in Morelos is likely to have consequences for the state's herpetofauna. Here a checklist of the amphibians and reptiles of Morelos is provided with a summary of their conservation status and overlap with its neighboring states. Morelos is home to 139 species of amphibians and reptiles representing 32 families and 75 genera. Twenty-six of the 38 species of amphibians and 70 of the 101 species of reptiles that inhabit Morelos are endemic to Mexico. Fourteen species of amphibians and reptiles from Morelos are IUCN listed (i.e., Vulnerable, Near Threatened, or Endangered), 22 are placed in a protected category by SEMARNAT, and 41 are categorized as high risk by the EVS. The Tropical Deciduous Forest vegetation type hosts the greatest number of amphibian and reptile species in Morelos (84 species). Morelos shares the largest proportion of its herpetofauna with the State of Mexico (79.3%), Puebla (77.0%), and Guerrero (74.8%)
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