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Globally, cities face a range of transport-related environmental, social, and economic challenges, not least congestion, air pollution, and promotion of sustainable modes of public transport. Mobility hubs (MHs) have been identified as a mechanism to aid the move toward a sustainable transport network and are at various stages of implementation in cities throughout the world. The growing prevalence of MH schemes highlights the requirement for a holistic overview of MH networks to ascertain their characteristics and inform policy direction. Consequently, this study presents a review of current MH deployment and literature, with the aim of examining this global phenomenon and identifying a future research agenda. The study combines a comprehensive review of web searches with gray literature and a limited number of articles from academic journals. Twenty locations, at different stages of development and implementation, were identified as examples to be reviewed and analyzed, thereby providing a context for the review. Subsequently, four themes have emerged: objectives of MHs, format, location, and operational factors. Key findings include the importance of stakeholder engagement in design and location choices, the significance of branding, and connection with existing travel infrastructure including public transport and active travel. Additionally, the provision of amenities is common to MH schemes because it promotes usage and integration into the local landscape. From this detailed review of the state of MHs, a future research agenda has been identified, including further defining MHs, understanding the origin and applicability of MH objectives, considering day-to-day operations, policy transfer implications, and further evaluations of single and network MHs.

A main objective of the Mars 2020 rover mission (Perseverance) is to collect and preserve samples of rock and soil from the Martian surface. To accomplish this task, the Perseverance Rover carries ...

Strigolactones (SLs) are the most recently discovered phytohormones, and their roles in root architecture and metabolism are not fully understood. Here, we investigated four MORE AXILLARY GROWTH (MAX) SL mutants in Arabidopsis thaliana, max3-9, max4-1, max1-1 and max2-1, as well as the SL receptor mutant d14-1 and karrikin receptor mutant kai2-2. By characterising max2-1 and max4-1, we found that variation in SL biosynthesis modified multiple metabolic pathways in root tissue, including that of xyloglucan, triterpenoids, fatty acids and flavonoids. The transcription of key flavonoid biosynthetic genes, including TRANSPARENT TESTA4 (TT4) and TRANSPARENT TESTA5 (TT5) was downregulated in max2 roots and seedlings, indicating that the proposed MAX2 regulation of flavonoid biosynthesis has a widespread effect. We found an enrichment of BRI1-EMS-SUPPRESSOR 1 (BES1) targets amongst genes specifically altered in the max2 mutant, reflecting that the regulation of flavonoid biosynthesis likely occurs through the MAX2 degradation of BES1, a key brassinosteroid-related transcription factor. Finally, flavonoid accumulation decreased in max2-1 roots, supporting a role for MAX2 in regulating both SL and flavonoid biosynthesis.

This study compares a deep learning interpretation of 23 echocardiographic parameters—including cardiac volumes, ejection fraction, and Doppler measurements—with three repeated measurements by core lab sonographers. The primary outcome metric, the individual equivalence coefficient (IEC), compares the disagreement between deep learning and human readers relative to the disagreement among human readers. The pre-determined non-inferiority criterion is 0.25 for the upper bound of the 95% confidence interval. Among 602 anonymised echocardiographic studies from 600 people (421 with heart failure, 179 controls, 69% women), the point estimates of IEC are all

PIONEER is a high Q-resolution, single-crystal, polarized neutron diffractometer at the Second Target Station (STS), Oak Ridge National Laboratory. It will provide the unprecedented capability of measuring tiny crystals (0.001 mm3, i.e., x-ray diffraction size), ultra-thin films (10 nm thickness), and weak structural and magnetic transitions. PIONEER benefits from the increased peak brightness of STS cold-neutron sources and uses advanced Montel mirrors that are able to deliver a focused beam with a high brilliance transfer, a homogeneous profile, and a low background. Monte Carlo simulations suggest that the optimized instrument has a high theoretical peak brilliance of 2.9 × 1012 n cm−2 sr−1 Å−1 s−1 at 2.5 Å at the sample position, within a 5 × 5 mm2 region and a ±0.3° divergence range. The moderator-to-sample distance is 60 m, providing a nominal wavelength band of 4.3 Å with a wavelength resolution better than 0.2% in the wavelength range of 1.0–6.0 Å. PIONEER is capable of characterizing large-scale periodic structures up to 200 Å. With a sample-to-detector distance of 0.8 m, PIONEER accommodates various sample environments, including low/high temperature, high pressure, and high magnetic/electric field. A large cylindrical detector array (4.0 sr) with a radial collimator is planned to suppress the background scattering from sample environments. Bottom detector banks provide an additional 0.4 sr coverage or can be removed if needed to accommodate special sample environments. We present virtual experimental results to demonstrate the scientific performance of PIONEER in measuring tiny samples.

The Mars 2020 mission seeks to conduct a new scientific exploration on the surface of Mars. The Perseverance Rover will be sent to the surface of the Jezero Crater region to study its habitability, search for biosignatures of past life, acquire and cache samples for potential return, and prepare for possible human missions. To enable these objectives, an innovative Sampling and Caching Subsystem (SCS) has been developed and tested to allow the Perseverance Rover to acquire and cache rock core and regolith samples, prepare abraded rock surfaces, and support proximity science instruments. The SCS consists of the Robotic Arm (RA), the Turret and Corer, and the Adaptive Caching Assembly (ACA). These elements reside and interact both inside and outside of the Perseverance Rover to enable surface interactions, sample transfer, and caching. The main body of the Turret consists of the Coring Drill (Corer) with a Launch Abrading Bit initially installed prior to launch. Mounted to the Turret main structure are two proximity science instruments, SHERLOC and PIXL, as well as the Gas Dust Removal Tool (gDRT) and the Facility Contact Sensor (FCS). These work together with the RA to provide the sample acquisition, abraded surface preparation, and proximity science functions. The ACA is a network of assemblies largely inside the front belly of the Rover, which combine to perform the sample handling and caching functions of the mission. The ACA primarily consists of the Bit Carousel, the Sample Handling Assembly (SHA), End Effector (EE), Sample Tubes and their Sample Tube Storage Assembly (STSA), Seals and their Dispenser, Volume, and Tube Assembly (DVT), the Sealing Station, the Vision Station, the Cover Parking Lot, and additional supporting hardware. These components attach to the Caching Component Mounting Deck (CCMD) that is integrated with the Rover interior. This work describes these major elements of the SCS, with an emphasis on the functionality required to perform the set of tasks and interactions required by the subsystem. Key considerations of contamination control and biological cleanliness throughout the development of these hardware elements are also discussed. Additionally, aspects of testing and validating the functionality of the SCS are described. Early prototypes and tests matured the designs over several years and eventually led to the flight hardware and integrated testing in both Earth ambient and Mars-like environments. Multiple unique testbed venues were developed and used to enable testing from low-level mechanism operation through end-to-end sampling and caching interactions with the full subsystem and flight software. Various accomplishments from these testing efforts are highlighted. These past and ongoing tests support the successful preparations of the SCS on its pathway to operations on Mars.

Climate change science can trace its origins back to the early 19th Century although interest really took off in the 1980s, when public interest and research activity proliferated as the potential negative effects of global warming became clear. The impacts of climate change on the marine environment was receiving little attention at this time, but in recent years has started to “catch up” both in terms of research activity and public and policy interest. In the UK, the Marine Climate Change Impacts Partnership (MCCIP) has played a key role in transferring the emerging evidence base on marine climate change impacts to decision makers through the development of climate change report cards. Since publishing its first card back in 2006, the MCCIP cards have become established as the principal source of marine climate change impacts evidence for policy makers in the UK, and similar approaches have been adopted elsewhere. Here we broadly describe how the climate change evidence base has evolved over time, with a focus on the marine evidence base, and the approach adopted in the UK by MCCIP to rapidly transfer this evidence to end users. The SIIRMS model developed by MCCIP to ensure integrity and independence in the scientific translation process is explored, along with wider lessons learnt along the way (e.g. about communicating uncertainty) and the impact MCCIP has had on informing decision making.

The EU Marine Strategy Framework Directive (MSFD) requires member states to manage their marine ecosystems with the goal of achieving Good Environmental Status (GES) of all European Seas by 2020. Member states assess GES according to 11 descriptors set out in the MSFD, and their associated indicators. An ecosystem service approach is increasingly being advocated to ensure sustainable use of the environment, and sets of indicators have been defined for ecosystem service assessments. We considered whether a selection of GES indicators related to biological descriptors, D1 Biodiversity, D2 Non-indigenous species, D4 Food webs and D6 Seafloor integrity, may provide information relevant to ecosystem services, potentially allowing use of collected environmental data for more than one purpose. Published lists of indicators for seven selected marine ecosystem services were compared to 296 biodiversity-related indicators included within the DEVOTOOL catalogue, established for screening marine biodiversity indicators for the MSFD. We concluded that 64 of these biodiversity indicators are directly comparable to the ecosystem service indicators under consideration. All 296 biodiversity indicators were then reassessed objectively to decide which of them could be useful as ecosystem service indicators. To carry out this step in a consistent and transparent manner, guidelines were developed among the co-authors that helped the decision making process for each individual indicator. 247 biodiversity indicators were identified as potentially useful ecosystem service indicators. By highlighting the comparability between ecosystem service and biodiversity indicators it is hoped that future monitoring effort can be used not only to ensure that GES is attained, but also that ecosystem service provision is maximised. It is recommended that these indicators should be tested across EU regional seas to see if they are useful in practice, and if ecosystem service assessments are comparable across regional seas.

An examination of the due process issues that arise from quarantine in the United States, taking a look specifically at tuberculosis quarantine.

This paper discusses hardware and software improvements to the RoboSimian system leading up to and during the 2015 DARPA Robotics Challenge DRC Finals. Team RoboSimian achieved a 5th place finish by achieving 7 points in 47:59 min. We present an architecture that was structured to be adaptable at the lowest level and repeatable at the highest level. The low-level adaptability was achieved by leveraging tactile measurements from force torque sensors in the wrist coupled with whole-body motion primitives. We use the term "behaviors" to conceptualize this low-level adaptability. Each behavior is a contact-triggered state machine that enables execution of short-order manipulation and mobility tasks autonomously. At a high level, we focused on a teach-and-repeat style of development by storing executed behaviors and navigation poses in an object/task frame for recall later. This enabled us to perform tasks with high repeatability on competition day while being robust to task differences from practice to execution.

In recent decades, the body of evidence on climate change including that for marine impacts has grown rapidly leading to a number of challenges, including the need to collate and summarise a large volume of information and to be able to analyse and interpret complex messages for a wide variety of stakeholders from scientists to policy-makers and the wider public. The Marine Climate Change Impacts Partnership (MCCIP) has been functioning at the science-policy interface for over ten years collating, assessing and interpreting information on marine climate change impacts. This experience, and the fact that the MCCIP model is being more widely adopted nationally and globally, provides an opportunity to look at lessons learned in working in the science-policy interface with a focus on the Scientific Integrity and Independence Risk Management Scheme (SIIRMS). This scheme was developed by MCCIP as a framework for providing climate information and advice to policy and decision-makers. Examples are provided of the impact of MCCIP on policy and the development of marine legislation along with other examples of how marine biodiversity information being utilized for policy needs.

This article presents the hardware design and software algorithms of RoboSimian, a statically stable quadrupedal robot capable of both dexterous manipulation and versatile mobility in difficult terrain. The robot has generalized limbs and hands capable of mobility and manipulation, along with almost fully hemispherical three-dimensional sensing with passive stereo cameras. The system is semiautonomous, enabling low-bandwidth, high latency control operated from a standard laptop. Because limbs are used for mobility and manipulation, a single unified mobile manipulation planner is used to generate autonomous behaviors, including walking, sitting, climbing, grasping, and manipulating. The remote operator interface is optimized to designate, parametrize, sequence, and preview behaviors, which are then executed by the robot. RoboSimian placed fifth in the DARPA Robotics Challenge Trials, demonstrating its ability to perform disaster recovery tasks in degraded human environments.

Within the COST action EMBOS (European Marine Biodiversity Observatory System) the degree and variation of the diversity and densities of soft-bottom communities from the lower intertidal or the shallow subtidal was measured at 28 marine sites along the European coastline (Baltic, Atlantic, Mediterranean) using jointly agreed and harmonized protocols, tools and indicators. The hypothesis tested was that the diversity for all taxonomic groups would decrease with increasing latitude. The EMBOS system delivered accurate and comparable data on the diversity and densities of the soft sediment macrozoobenthic community over a large-scale gradient along the European coastline. In contrast to general biogeographic theory, species diversity showed no linear relationship with latitude, yet a bell-shaped relation was found. The diversity and densities of benthos were mostly positively correlated with environmental factors such as temperature, salinity, mud and organic matter content in sediment, or wave height, and related with location characteristics such as system type (lagoons, estuaries, open coast) or stratum (intertidal, subtidal). For some relationships, a maximum (e.g. temperature from 15–20°C; mud content of sediment around 40%) or bimodal curve (e.g. salinity) was found. In lagoons the densities were twice higher than in other locations, and at open coasts the diversity was much lower than in other locations. We conclude that latitudinal trends and regional differences in diversity and densities are strongly influenced by, i.e. merely the result of, particular sets and ranges of environmental factors and location characteristics specific to certain areas, such as the Baltic, with typical salinity clines (favouring insects) and the Mediterranean, with higher temperatures (favouring crustaceans). Therefore, eventual trends with latitude are primarily indirect and so can be overcome by local variation of environmental factors.

In this paper, we present the argument in favor of an open source, a royalty-free video codec that will keep pace with the evolution of video traffic. Additionally, we argue that the availability of a state-of-the-art, royalty-free codec levels the playing field, allowing small content owners, and application developers to compete with the larger companies that operate in this space.

Crossrail Project Infrastructure Design and Construction: Volume 4

A rock-climbing robot is presented that can free climb on vertical, overhanging, and inverted rock faces. This type of system has applications to extreme terrain on Mars or for sustained mobility on microgravity bodies. The robot grips the rock using hierarchical arrays of microspines. Microspines are compliant mechanisms made of sharp hooks and flexible elements that allow the hooks to move independently and opportunistically grasp roughness on the surface of a rock. This paper presents many improvements to early microspine grippers, and the application of these new grippers to a four-limbed robotic system, LEMUR IIB. Each gripper has over 250 microspines distributed in 16 carriages. Carriages also move independently with compliance to conform to larger, cm-scale roughness. Single gripper pull testing on a variety of rock types is presented, and on rough rocks, a single gripper can support the entire mass of the robot (10 kg) in any orientation. Several sensor combinations for the grippers were evaluated using a smaller test-gripper. Rock-climbing mobility experiments are also described for three characteristic gravitational orientations. Finally, a sample acquisition tool that uses one of the robot's grippers to enable rotary percussive drilling is shown.

MATTHEW FROST, JOHN M. BAXTER, PAUL J. BUCKLEY, MARTYN COX, STEPHEN R. DYE* and NARUMON WITHERS HARVEY Marine Biological Association of the United Kingdom, Plymouth, PL1 2PB, UK Scottish Natural Heritage, Silvan House, 231 Corstorphine Road, Edinburgh, EH12 7AT, UK MCCIP Secretariat, Cefas, Lowestoft, NR33 0HT, UK Marine Scotland, Scottish Government, Edinburgh, EH6 6QQ, UK Marine Environmental Strategy and Evidence, Defra, London, SW1P 3JR, UK

Regime shifts are sudden changes in ecosystem structure that can be detected across several ecosystem components. The concept that regime shifts are common in marine ecosystems has gained popularity in recent years. Many studies have searched for the step-like changes in ecosystem state expected under a simple interpretation of this idea. However, other kinds of change, such as pervasive trends, have often been ignored. We assembled over 300 ecological time series from seven UK marine regions, covering two to three decades. We developed state-space models for the first principal component of the time series in each region, a common measure of ecosystem state. Our models allowed both trends and step changes, possibly in combination. We found trends in three of seven regions and step changes in two of seven regions. Gradual and sudden changes are therefore important trajectories to consider in marine ecosystems.

The first European Marine Biology Symposium (EMBS) was initiated by Otto Kinne, Director of the Biologische Anstalt Helgoland, and held on Helgoland in the early autumn of 1966. The meeting was such a success that the EMBS has continued to be held annually ever since, moving around various locations. To date the EMBS has been organized in about 20 different European countries (Hummel & Hummel, 2016). The overall aim of the EMBS is to advance the science of Marine Biology within Europe. The EMBS provides a forum for the presentation of current marine biological research through a combination of oral and poster presentations, to encourage a wider interest in Marine Biology, an awareness of the need for the proper management of European seas and coasts, and the fostering of inter-European links and cooperation between researchers in Marine Biology. The scientific topics usually reflect the interest of the organizing institution, time series research in the case of the 50th EMBS.

The English Channel is located at the biogeographical boundary between the northern Boreal and southern Lusitanian biozones and therefore represents an important area to study the effects of global warming on marine organisms. While the consequences of climatic change in the western English Channel have been relatively well documented for fish, plankton and inter-tidal benthic communities, data highlighting the same effects on the distribution of sub-littoral benthic organisms does, to date, not exist. The present study resurveyed a subset of sites originally surveyed from 1958 to 1959 along the UK coast of the English Channel. The main aims of this resurvey were to describe the present status of benthic communities and to investigate potential temporal changes, in particular distributional changes in western stenothermal 'cold' water and southern Lusitanian 'warm' water species. The increase in water temperature observed since the historic survey was pre- dicted to have caused a contraction in the distribution of cold water species and an extension in the distribution of warm water species. The temporal comparison did not show any clear broad-scale dis- tributional changes in benthic communities consistent with these predictions. Nevertheless, 2 warm water species, the sting winkle Ocenebra erinacea and the introduced American slipper limpet Crepidula fornicata, did show range extensions and increased occurrence, possibly related to cli- matic warming. Similarly, warm water species previously not recorded by the historic survey were found. The absence of broad-scale temporal differences in sub-tidal communities in response to cli- matic warming has been reported for other areas and may indicate that these communities respond far more slowly to environmental changes compared to plankton, fish and inter-tidal organisms.

A regime shift is a large, sudden, and long-lasting change in the dynamics of an ecosystem, affecting multiple trophic levels. There are a growing number of papers that report regime shifts in marine ecosystems. However, the evidence for regime shifts is equivocal, because the methods used to detect them are not yet well developed. We have collated over 300 biological time series from seven marine regions around the UK, covering the ecosystem from phytoplankton to marine mammals. Each time series consists of annual measures of abundance for a single group of organisms over several decades. We summarised the data for each region using the first principal component, weighting either each time series or each biological component (e.g. plankton, fish, benthos) equally. We then searched for regime shifts using Rodionov’s regime shift detection (RSD) method, which found regime shifts in the first principal component for all seven marine regions. However, there are consistent temporal trends in the data for six of the seven regions. Such trends violate the assumptions of RSD. Thus, the regime shifts detected by RSD in six of the seven regions are likely to be artefacts caused by temporal trends. We are therefore developing more appropriate time series models for both single populations and whole communities that will explicitly model temporal trends and should increase our ability to detect true regime shift events.

Since the early part of the 20th Century the impact of a range of anthropogenic activities in our coastal seas has steadily increased. The effect of such activities is a major cause for concern but in the benthic environment few studies exist that date back more than a few decades. Hence understanding long term changes is a challenge. Within this study we utilized a historic benthic dataset and resurveyed an area west of Eddystone reef in the English Channel previously investigated 112 years ago. The aim of the present work was to describe the current benthic community structure and investigate potential differences between 1895 and 2007. For each of the four major phyla investigated (Polychaeta, Crustacea, Mollusca and Echinodermata), multivariate community analysis showed significant differences between the historic and contemporary surveys. Echinoderm diversity showed a clear reduction between 1895 and 2007. The sea urchins Echinus esculentus, Spatangus purpureus, and Psammechinus miliaris and large star-fish Marthasterias glacialis showed reductions in abundance, in some cases being entirely absent from the survey area in 2007. Polychaetes showed a shift from tubiculous species to small errant and predatory species such as Glycera, Nephtys, and Lumbrineris spp. Within the group Mollusca large species such as Pecten maximus and Laevicardium crassum decreased in abundance while small species increased. Crustaceans in 1895 were dominated by crab species which were present in similar abundances in 2007, but, the order Amphipoda appeared to show a significant increase. While some of the differences observed could stem from differences in methodologies between the surveys, in particular increases of small cryptic species, the loss of large conspicuous species was judged to be genuine. The study area is an important beam trawling and scallop dredging ground; the differences observed are concomitant with changes generally associated with disturbance from demersal fishing activities such as these.

Biogenic reefs are important for habitat provision and coastal protection. Long-term datasets on the distribution and abundance of Sabellaria alveolata (L.) are available from Britain. The aim of this study was to combine historical records and contemporary data to (1) describe spatio-temporal variation in winter temperatures, (2) document short-term and long-term changes in the distribution and abundance of S. alveolata and discuss these changes in relation to extreme weather events and recent warming, and (3) assess the potential for artificial coastal defense structures to function as habitat for S. alveolata. A semi-quantitative abundance scale (ACFOR) was used to compare broadscale, long-term and interannual abundance of S. alveolata near its range edge in NW Britain. S. alveolata disappeared from the North Wales and Wirral coastlines where it had been abundant prior to the cold winter of 1962/1963. Population declines were also observed following the recent cold winters of 2009/2010 and 2010/2011. Extensive surveys in 2004 and 2012 revealed that S. alveolata had recolonized locations from which it had previously disappeared. Furthermore, it had increased in abundance at many locations, possibly in response to recent warming. S. alveolata was recorded on the majority of artificial coastal defense structures surveyed, suggesting that the proliferation of artificial coastal defense structures along this stretch of coastline may have enabled S. alveolata to spread across stretches of unsuitable natural habitat. Long-term and broadscale contextual monitoring is essential for monitoring responses of organisms to climate change. Historical data and gray literature can be invaluable sources of information. Our results support the theory that Lusitanian species are responding positively to climate warming but also that short-term extreme weather events can have potentially devastating widespread and lasting effects on organisms. Furthermore, the proliferation of coastal defense structures has implications for phylogeography, population genetics, and connectivity of coastal populations.

49th European Marine Biology Symposium (EMBS) -- SEP 08-12, 2014 -- Saint Petersburg, RUSSIA, WOS: 000364937700002, The degree of development and operability of the indicators for the Marine Strategy Framework Directive (MSFD) using Descriptor 1 (D1) Biological Diversity was assessed. To this end, an overview of the relevance and degree of operability of the underlying parameters across 20 European countries was compiled by analysing national directives, legislation, regulations, and publicly available reports. Marked differences were found between countries in the degree of ecological relevance as well as in the degree of implementation and operability of the parameters chosen to indicate biological diversity. The best scoring EU countries were France, Germany, Greece and Spain, while the worst scoring countries were Italy and Slovenia. No country achieved maximum scores for the implementation of MSFD D1. The non-EU countries Norway and Turkey score as highly as the top-scoring EU countries. On the positive side, the chosen parameters for D1 indicators were generally identified as being an ecologically relevant reflection of Biological Diversity. On the negative side however, less than half of the chosen parameters are currently operational. It appears that at a pan-European level, no consistent and harmonized approach currently exists for the description and assessment of marine biological diversity. The implementation of the MSFD Descriptor 1 for Europe as a whole can therefore at best be marked as moderately successful., Russian Acad Sci, Zool Inst, COST Action ES1003 EMBOS on the Development and Implementation of a Pan-European Marine Biodiversity Observatory System; MARES Grant under the Erasmus Mundus framework [FPA 2011- 0016]; SZN PhD fellowship; Portuguese PhD FCT grant [SFRH/BD/84933/2012], Meetings to prepare this paper were made possible by funding through COST Action ES1003 EMBOS on the Development and Implementation of a Pan-European Marine Biodiversity Observatory System. Carlos Castellanos Perez Bolde acknowledges MARES Grant FPA 2011- 0016 under the Erasmus Mundus framework, Marlene Jahnke has been supported by a SZN PhD fellowship, and Joao N. Franco by Portuguese PhD FCT grant SFRH/BD/84933/2012.

Adaptive management of the marine environment requires an understanding of the complex interactions within it. Establishing levels of natural variability within and between marine ecosystems is a necessary prerequisite to this process and requires a monitoring programme which takes account of the issues of time, space and scale. In this paper, we argue that an ecosystem approach to managing the marine environment should take direct account of climate change indicators at a regional level if it is to cope with the unprecedented change expected as a result of human impacts on the earth climate system. We discuss the purpose of environmental monitoring and the importance of maintaining long-term time series. Recommendations are made on the use of these data in conjunction with modern extrapolation and integration tools (e.g. ecosystem models, remote sensing) to provide a diagnostic approach to the management of marine ecosystems, based on adaptive indicators and dynamic baselines.

We studied the relationship between abundance and extent of occupancy of 158 species of macrofauna inhabiting 66 sandy beaches around the coast of Great Britain. We also used these data to test the predictions of two hypotheses proposed to explain positive abundance-occupancy relationships. We found a strong positive relationship between abundance and extent of occupancy; this pattern was apparent in taxonomic subsets of organisms which have contrasting reproductive and dispersal traits such as planktotrophic/lecithotrophic development in the plankton vs brood development under parental care. Moreover, the abundance-occupancy relationships in these taxonomic subsets had statistically indistinguishable slopes, and elevation. We propose that this lends support to the notion that differences in population structure such as the tendency to form metapopulations may not be primary determinants of the abundance-occupancy pattern in these taxa as proposed by the rescue/metapopulation hypothesis. To test the predictions of the niche-breadth hypothesis we derived values describing the range of sediment grain-sizes exploited by members of two taxonomic subgroups: amphipods and bivalves. We found a weak, statistically non-significant relationship between this niche-breadth measure and occupancy in bivalves which have been shown to respond to grain-size in previous studies, however this was negated after correction for possible artefacts of sampling effort. All other relationships between abundance or occupancy and grain-size range were non-significant. The consistency of the demonstrated abundance-occupancy relationship with those demonstrated in other studies of primarily terrestrial fauna indicates some shared mechanistic explanation, but our data fail to provide support for the two mechanistic hypotheses investigated.

The number of species in an assemblage at a given point in time is a fundamental prop- erty of ecological systems, yet it is hard to quantify for many marine systems. We studied the perfor- mance of 6 techniques ('estimators') for extrapolating species richness from limited numbers of sam- ples, using 3 datasets for which an absolute value for total species richness could be determined. We propose that the ideal estimator should always slightly overestimate species richness compared to any observed maximum species richness derived from sampling, as sampling error will always lead to underestimation of true richness. We quantified performance of the estimators relative to the sam- pled total richness in the assemblage across a range of efforts up to 80% of that required to achieve the asymptote of the species accumulation. We used 3 measures: bias (mean deviation of an estimate from the known richness), precision (variance of repeated estimates based upon a subset of the avail- able pool of samples), and overall accuracy (a combination of bias and precision). No single estima- tor performed best in all cases, and estimator performance was affected by sampling effort. The esti- mator Chao1 performed best at intermediate sampling efforts, with LAG S∞ also performing well at high relative effort. S∞ consistently underestimated, whilst Chao2 and ICE both overestimated and displayed poor precision and accuracy, especially at intermediate sampling efforts and in datasets with uneven patterns of species incidence. Species abundance and incidence amongst samples of a dataset were shown to affect performance of most of the estimators, with the exception of the recently proposed S∞ family of techniques. We conclude that Chao1 represents the best compromise choice of estimator, and that such nonparametric techniques may represent useful tools for rapid estimation of species richness for some marine assemblages, based on limited sampling effort.

Macroecology is essentially concerned with understanding the large-scale patterns in organisms' abundance and distribution, and determining how these patterns arise. Whilst macroeco- logical studies abound in terrestrial and freshwater ecology, few comparable studies have ever been conducted using marine data. We examined the relationships between mean organismal abundance and the extent of site occupancy of 95 species of estuarine macroinvertebrates, censused over 143 grid squares of 1 km spread across the UK. A significant positive relationship between abundance and occupancy was revealed, with the slope of this relationship not differing significantly between taxonomic groups. Taxa with planktonic/lecithotrophic larvae showed no significant difference in abundance-occupancy slope compared to taxa with other reproductive/dispersal biologies. The pat- terns observed are consistent with those reported in many studies of terrestrial and freshwater taxa.