Variation in the chemical composition of fish otoliths has been used in recent years to address a range of ecological questions, including levels of stock mixing, variation in habitat use, and rates of larval exchange. While some of these questions have been answered with varying success, the degree to which discrete populations are connected via larval exchange remains unknown. To identify larval sources using natural variation in otolith chemistry, we must distinguish and measure the chemical composition of the otolith core, the portion of the otolith formed at the spawning site. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), we found that the core regions of otoliths from 6 different species of fishes were highly enriched in manganese (Mn), and elevated in magnesium (Mg) and barium (Ba), relative to adjacent regions of the otolith. These patterns were consistent for species drawn from different taxonomic groups, which inhabit temperate and tropical regions, are found in marine and freshwater, and utilize a variety of spawning modes. Variation among species in Mn concentration in the core also corresponds to maternal investment, measured by egg size. These data suggest that core enrichment may be a general characteristic of otoliths, and that the chemical composition of the otolith core is fundamentally different from other regions of the otolith. The localized elemental enrichment of the core underscores the importance of methods that analyze the core region in small, discrete samples if otolith chemistry is used to address questions of larval exchange among populations.

We show that chemical differences found along the open coast are sufficiently strong to leave a readable natal signature in fish otoliths. Laser ablation inductively coupled plasma mass spectrometric (LA-ICPMS) analysis of individual larval otoliths taken from near-term females of the primitively viviparous rockfish Sebastes atrovirens indicates detectable levels of several trace elements. Although these larvae show considerable between-brood differences in elemental concentrations for females taken at the same site, there was significant between-site discrimination of natal signatures for regions only tens of kilometers apart in the waters off of Santa Barbara, California. For several (but not all) elements, differences between regions were consistent between 2 yr. We also explore three different possible proxies (edges of otoliths of adult fishes, resin-based elemental accumulators, and samples of seawater) that might be used to predict geographic differences in natal signatures. Although these proxies all showed significant regional differences in the concentration of some elements, only manganese showed some congruency in the spatial patterns seen in the larval otoliths. Consequently, currently available proxy measures cannot accurately predict the elemental composition of otolith cores.One of the least understood and most fundamental processes in the determination of population abundance and community structure in marine ecosystems is dispersal, or transport, of pelagic larvae. To what extent are local adult population dynamics influenced by the dispersal of larvae from neighboring source populations? Do self-recruiting populations exist? How far do larvae disperse? The sources and destinations of larvae have been unknown, and are seemingly unknowable, for nearly all commercially important species, and yet any model of resource management or biodiversity preservation depends on certain assumptions about transport and connectivity between marine populations.The small size and long development time of the larvae of most marine animals have made studies of dispersal difficult. Small animals usually cannot be burdened with tags, and high mortality and potentially widespread dispersal of 1 Corresponding author (warner@lifesci.ucsb.edu). AcknowledgmentsThis work was supported by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO, funded by the David and Lucille Packard Foundation) and by the Coastal Environmental Quality Initiative (CEQI, funded by the University of California). We thank N. Kashef, D. Stafford, J. Standish, and D. Zacherl for technical assistance and advice, and three anonymous reviewers for their insight. This is PISCO publication 174.

During the last glaciation, most of the British Isles and the surrounding continental shelf were covered by the BritishIrish Ice Sheet (BIIS). An earlier compilation from the existing literature (BRITICE version 1) assembled the relevant glacial geomorphological evidence into a freely available GIS geodatabase and map (Clark et al. 2004: Boreas 33, 359). New high-resolution digital elevation models, of the land and seabed, have become available casting the glacial landform record of the British Isles in a new light and highlighting the shortcomings of the V.1 BRITICE compilation. Here we present awholesale revision of the evidence, onshore and offshore, to produce BRITICE version 2, which now also includes Ireland. All published geomorphological evidence pertinent to the behaviour of the ice sheet is included, up to the census date of December 2015. The revised GIS database contains over 170 000 geospatially referenced and attributed elements -an eightfold increase in information from the previous version. The compiled data include: drumlins, ribbed moraine, crag-and-tails, mega-scale glacial lineations, glacially streamlined bedrock (grooves, roches moutonn ees, whalebacks), glacial erratics, eskers, meltwater channels (subglacial, lateral, proglacial and tunnel valleys), moraines, trimlines, cirques, trough-mouth fans and evidence defining ice-dammed lakes. The increased volume of features necessitates different map/database products with varying levels of data generalization, namely: (i) an unfiltered GIS database containing all mapping; (ii) a filtered GIS database, resolving data conflicts and with edits to improve geo-locational accuracy (available as GIS data and PDF maps); and (iii) a cartographically generalized map to provide an overviewof the distribution and types of features at the ice-sheet scale that can be printed at A0 paper size at a 1:1 250 000 scale. All GIS data, the maps (as PDFs) and a bibliography of all published sources are available for download from: https://www.sheffield.ac.uk/geography/staff/clark_chris/britice. Palaeo-ice sheets provide the opportunity to study icesheet behaviour over a longer time period (10 000s of years) than can be achieved by studying current ice sheets (10s of years) thereby permitting exploration of the long-term role of ice sheets in the climate system. The extent, geometry and dynamics of palaeo-ice sheets can be reconstructed from the geomorphological and geological evidence they leave behind, with the mapping, logging and description of such evidence being the vital ingredients. For many palaeo-ice sheets, such as the British-Irish Ice Sheet (BIIS), the accumulation of evidence at individual field-sites has been ongoing for well over 100 years (e.g. Geikie 1894) yielding thousands of publications. Using such work to build local to regional reconstructions of ice dynamics is feasible, but at the ice-sheet scale the volume of information becomes unmanageable. Often the information is spread across so many publications and across many decades of work, where...

Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544km 2 landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98Mkm 2 (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization.

As with many marine species, the vast majority of coral-reef fishes have a bipartite life cycle consisting of a dispersive larval stage and a benthic adult stage. While the potentially far-reaching demographic and ecological consequences of marine dispersal are widely appreciated, little is known of the structure of the larval pool and of the dispersive process itself. Utilizing Palindrome Sequence Analysis of otolith micro-chemistry (PaSA;) we show that larvae of Neopomacentrus miryae (Pomacentridae) appear to remain in cohesive cohorts throughout their entire pelagic larval duration (PLD; ∼28 days). Genetically, we found cohort members to be maternally (mtDNA) unrelated. While physical forcing cannot be negated as contributing to initial cohort formation, the small scale of the observed spatial structure suggests that some behavioral modification may be involved from a very early age. This study contributes to our ongoing re-evaluation of the processes that structure marine populations and communities and the spatial scales at which they operate.

Variation of trace elemental composition in fish otoliths has been successfully used to reconstruct the environmental history of fish, including the movement of early life stages among populations and habitats. Past studies have focused primarily on estuarine-dependent species, and information has been very limited for species that spawn along open coastlines, where spawning locations are not discrete and environmental gradients are less extreme. In this study, we used defined natal otolith elemental signatures from pre-pelagic larvae of the viviparous kelp rockfish Sebastes atrovirens taken from the natal source along the open coast of California and the offshore Channel Islands to identify the dispersal patterns of recently recruited individuals from the Channel Islands. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), we chemically analyzed the otolith core (the portion of the otolith corresponding to the period of time prior to larval release) of recruits and compared the elemental signatures to spatially restricted natal otolith elemental signatures in southern California. Linear discriminant function analysis (DFA) revealed that the natal elemental signature of the mainland California location was not apparent in the elemental signatures of Channel Island recruit cores, suggesting a lack of exchange among the locations for the recruitment year. Several recruits had core elemental signatures that differed from all defined natal locations, suggesting that they originated from an uncharacterized site. These data demonstrate the use of natal otolith chemical data within a limited geographic area to identify larval dispersal patterns, with particular focus on sources that do not contribute to the defined locations.KEY WORDS: Otolith chemistry · Otolith core · Larvae · Trace element · LA-ICPMS · Dispersal · Population connectivity 356: 259-268, 2008 ods have provided valuable insights into the larval dispersal process, they do not provide information on the specific origin of individuals. Alternative techniques that can explicitly determine the natal source and movement of larvae are needed. Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerRecently, environmental markers such as the isotopic and elemental composition in the hard parts of fishes and invertebrates have shown great promise as a means to track the history and quantify movement among populations (DiBacco & Levin 2000, Thorrold et al. 2001, Gillanders 2002, Becker et al. 2007). In fishes, this technique generally employs the otolith, a structure situated in the inner ear and used for vertical orientation and hearing. Formed during the embryonic stage, otoliths grow by the daily accretion of calcium carbonate into a proteinaceous matrix, generating a pattern of concentric rings around the central nucleus. The central nucleus forms the core of the otolith as the fish grows. Trace elements from the environment are incorporated into the calcium carbonate matrix of the ...

Elemental signatures have been used as a tool to track individual organisms to their natal site in an attempt to understand stock structure and larval dispersal. However, factors that affect elemental signatures are not well understood. We conducted a factorial experiment using whelk Kelletia kelletii larvae from Salta Verde Point on Catalina Island, Los Angeles Harbor, and White Point, Palos Verdes peninsula, California, USA, to test the effects of egg source, temperature (10, 14 and 18°C) and culture seawater on the elemental composition of larval statoliths. Intra-capsular contents of newly laid capsules were also analyzed to explore whether maternal contributions might affect larval statolith chemistry. Using inductively coupled plasma mass spectrometry we quantified ratios of 7 elements to calcium in both intra-capsular contents and cultured statoliths and provided the first evidence of significant egg-source effects, independent of subsequently experienced environmental conditions, on statolith elemental signatures for Mg:Ca, Ba:Ca and Pb:Ca. Intra-capsular and statolith element ratios showed no clear relationship that might have indicated possible maternal transfer of elements to larvae. Culture seawater elemental concentration was positively related to statolith Ba:Ca and Pb:Ca, and temperature was negatively related to statolith Sr:Ca, Ba:Ca and Pb:Ca, while no significant effects were found for Mn:Ca or Zn:Ca. Effect-size estimates show that elements responded differently to factors within the variation measured in this study; the major effects for Ba and Pb were temperature and egg source, respectively. The significant effect of egg source on elemental signatures has potentially important implications for tracking free-spawned larvae. KEY WORDS: Statolith · LA ICP-MS · Dispersal · Egg source · Relative effects · Elemental signature · Kelletia kelletiiResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 353: 115-130, 2008 natural signatures of stock structure (e.g. , as records of dispersal and migration pathways (e.g. Ikeda et al. 2003) and for identifying spawning and nursery grounds (e.g. Gillanders & Kingsford 2003).In particular, the elemental composition of the larval calcified structures of fish (Swearer et al. 1999), crabs (DiBacco & Levin 2000), bivalves (Becker et al. 2007) and gastropods (Zacherl 2005) has potential to elucidate much useful information about larval origin and dispersal trajectories. Many larvae begin forming their calcified structures at or near the site of production and, thus, potentially carry a permanent elemental signature of the site of origin. When larvae enter the water column and move through ocean masses with variable physical and chemical characteristics, these changes can be recorded in the elemental composition of calcified structures. In principle, not only can the site of origin be identified, but subsequent larval movement also can be tracked using statolith elemental signatures.To identify any particul...

Fish otoliths are a reliable source of historical data regarding individual fish. Optical and chemical data obtained from otoliths are used to reveal the fish's age, natal areas, dispersal trajectories, and more. However, whereas optical methods are well established and widely practiced, methods for obtaining and interpreting chemical data continue to evolve. Despite rapid advances in the past decade, analytical approaches to otolith microchemisty continue to develop as new opportunities and limitations emerge. Otolith chemistry often reflects environmental conditions such as the chemical composition, temperature, and salinity of the ambient water. However, it is not always clear how these interact to produce the chemical signature observed in the otolith. Such gaps and inconsistencies in our knowledge may result partly from valuable information being discarded when measured concentrations fall below customarily defined detection limits (DL). Below we review some of the inaccuracies that may arise when analyzing chemical data obtained from laser-ablation inductively coupled mass spectrometry (LA-ICPMS). We argue that measurements traditionally defined as sub-DL can contain valuable information that would otherwise be discarded. We base our argument on the analysis of sub-DL signals obtained from both sides of otoliths core. Specifically, we show that these signals often form sequences that are symmetrical about the core (palindrome), and that the probability of obtaining even the simplest palindromic sequence by chance falls well below the customary 5% significance level. We conclude by discussing how this microchemical data can be analyzed in a manner that is insensitive to errors in concentration readings.