Regional variation in springtime ichthyoplankton assemblages in the northeast Pacific Ocean

The coastal regions of the northeast Pacific support large, economically valuable fishery resources and provide nursery areas for many fish species. Over the last few decades, there have been dramatic shifts in species abundance and composition in this area. In this paper, we examine the springtime spatial patterns in the ichthyoplankton of three oceanographically different regions, the Southeast Bering Sea, the Gulf of Alaska and the U.S. West Coast. The data examined are a subset of a larger database (comprising data from cruises conducted from 1972 to 1997) that is being used to investigate spatial, seasonal and interannual patterns in ichthyoplankton of the northeast Pacific in relation to environmental conditions. Ichthyoplankton were collected during seven cruises using 60-cm bongo nets. Spatial patterns of ichthyoplankton were examined using both classification and ordination techniques. Relative Bray-Curtis dissimilarity coefficients calculated from the log₁₀ (n+1) of abundance data were used as input to the numerical classification of species and stations. Nonmetric multidimensional scaling was also applied to the abundance data to examine geometric patterns in the data. The numerical analyses of the species abundance data sets for each cruise revealed spatial patterns in the ichthyoplankton that suggest the occurrence of geographically distinct assemblages of fish larvae in each region. For all three sampling regions, the assemblage structure is primarily related to bathymetry, and Shelf, Slope, and Deep-Water assemblages are described. This shallow to deep-water gradient in species occurrence and abundance reflects the habitat preference and spawning location of the adult fish. Another degree of complexity is superimposed on this primary assemblage structure in each region and seems to be related to local topography and the prevailing current patterns. The patterns in ichthyoplankton assemblages of the three regions in the northeast Pacific Ocean described here form the basis for future investigations of spatial and temporal patterns in the ichthyoplankton of the subarctic Pacific.Regional Index Terms: Northeast Pacific Ocean, Southeast Bering Sea, Gulf of Alaska, U.S. West Coast.     

Predicting the distribution of deep-sea vulnerable marine ecosystems using high-resolution data: Considerations and novel approaches

Little is known about species distribution patterns in deep-sea environments, primarily because sampling surveys in the high seas are expensive and time consuming. The increasing need to manage and protect vulnerable marine ecosystems, such as cold-water corals, has motivated the use of predictive modelling tools, which produce continuous maps of potential species or habitat distribution from limited point observations and full coverage environmental data. Rapid advances in acoustic remote sensing, oceanographic modelling and sampling technology now provide high quality datasets, facilitating model development with high spatial detail. This paper provides a short overview of existing methodologies for predicting deep-sea benthic species distribution, and illustrates emerging issues related to spatial and thematic data resolution, and the use of transect-derived species distribution data. In order to enhance the ecological relevance and reliability of deep-sea species distribution models, novel techniques are presented based on a case study predicting the distribution of the cold-water coral Lophelia pertusa in three carbonate mound provinces in Irish waters. Specifically, the study evaluates (1) the capacity of newly developed high-resolution (250 m grid cell size) hydrodynamic variables to explain local scale cold-water coral distribution patterns, (2) the potential value of species occurrence proportion data to maintain semi-quantitative information of coral prevalence (i.e. coverage) and sampling effort per grid cell within the response variable, and (3) mixed effect modelling to deal with spatially grouped transect data. The study shows that predictive models using vertical and horizontal flow parameters perform significantly better than models based on terrain parameters only. Semi-quantitative proportion data may decrease model uncertainty and increase model reliability, and provide a fruitful avenue of research for analysing large quantities of video data in a detailed yet time-efficient manner. The study concludes with an outlook of how species distribution models could improve our understanding of vulnerable marine ecosystem functioning and processes in the deep sea.     

Describing and generating facies models for reservoir characterisation: 2D map view

This paper documents a new method for describing channel-related sedimentary deposits based on formal language theory. Using this method an analogue model of a sedimentary deposit can be encoded as a grammar. A program, called a parser, has been developed which can generate stochastic maps of these sedimentary deposits based on information in a specified grammar. The maps of sedimentary deposits generated by the parser have the same type, spatial arrangement, shape and size distribution as the analogue model. The successful generation of depositional maps represents a crucial step in the ongoing development of a new technique designed to generate 3D static geological models of sedimentary successions. The maps can be conditioned to match sparse hard data in the form of channel segments interpreted from seismic horizon maps.     

Biodiversity patterns of free-living marine nematodes in a tropical bay: Cienfuegos, Caribbean Sea

Spatial and temporal biodiversity patterns of free-living marine nematodes were studied in Cienfuegos Bay, a tropical semi-enclosed basin in the Caribbean Sea. Taxonomic (to species level) and functional (biological trait) approaches were applied for describing the assemblage structure and relating it to abiotic environment based on a sampling scheme in six subtidal stations and three months. Biological trait approach added relevant information to species pattern regarding relationships between diversity patterns and the abiotic environment. The most common morphotypes were deposit feeding nematodes, with colonising abilities of 2–3 (in a scale from 1 to 5), tail conical cylindrical or filiforme and body slender; and their abundance were correlated with depth, organic matter and silt/clay fraction. In spite of a high turnover of species, functional diversity of assemblages did not change notably in space and time. A result probably due to sampling of the habitat pool of species and to low heterogeneity of the studied muddy bottoms. Chemical pollution (organic enrichment and heavy metals) and hydrodynamic regime possibly drove the biodiversity patterns. Spatial distribution of assemblages support the existence of two well differentiated basins inside the bay, the northern basin more polluted than the southern one. The low hydrodynamic regime would determine a poor dispersion of nematodes resulting in high spatial variance in the assemblage structure; and also the associated hypoxic conditions and pollutants in sediments can explain the dominance of tolerant nematode species such as Daptonema oxycerca, Sabatieria pulchra, Terschellingia gourbaultae, and Terschellingia longicaudata. A comparison of spatial–temporal patterns of biodiversity between Cienfuegos Bay and other semi-enclosed bays in temperate regions suggests several similarities: nematode assemblages are strongly influenced by anthropogenic disturbance, temporal trends are weak or overridden by spatial ones, and few cosmopolitan genera/species tolerant to pollution and hypoxic conditions are dominant.     

Assessing the suitability of commercial fisheries data for local-scale marine spatial planning in South Africa

This study integrates fisheries logbook data with observer and vessel monitoring system (VMS) data in order to assess the accuracy of reported data and to develop high-resolution spatial data suitable for use in local-scale marine spatial planning analyses. Spatial assessments were conducted on five nearshore commercial fisheries to provide baseline information to inform spatial management and conservation planning in Algoa Bay, South Africa. Clear spatial patterns in the distribution of fishing effort were apparent for the linefishery, chokka-squid and inshore demersal trawl sectors. Observer and VMS data confirmed the broad spatial distribution of resource-use patterns of logbook data. Combining these data sources allowed higher-resolution spatial indices of fishing effort to be developed, which are suitable for systematic spatial planning on a local scale and can be used for future spatial management and conservation.     

Modelling the spatial distribution of plaice (Pleuronectes platessa), sole (Solea solea) and thornback ray (Raja clavata) in UK waters for marine management and planning

Species distribution maps are needed for ecosystem-based marine management including the development of marine spatial plans. If such maps are based on predictive models then modelling procedures should aim to maximise validation success, and any uncertainty in the predictions needs to be made explicit. We developed a predictive modelling approach to produce robust maps of the distributions of selected marine species at a regional scale. We used 14 years of survey data to map the distributions of plaice, sole and thornback ray in three hydrographic regions comprising parts of the Irish Sea, Celtic Sea and the English Channel with the help of the hybrid technique regression kriging, which combines regression models with geostatistical tools. For each species–region combination we constructed logistic Generalized Linear Models (GLMs) based on presence–absence data using the environmental variables: depth, bottom temperature, bed shear stress and sediment type, as predictors. We selected GLMs using the mean squared error of prediction (MSEP) estimated by cross-validation then conducted a geostatistical analysis of the residuals to incorporate spatial structure in the predictions. In general, we found that species occurrence was positively related to shallow areas, a bed shear stress of between 0 and 1.5 N/m², and the presence of sandy sediment. Predicted species occurrence probabilities were in good agreement with survey observations. This modelling framework selects environmental models based on predictive ability and considers the effect of spatial autocorrelation on predictions, together with the simultaneous presentation of observations, associated uncertainties, and predictions. The potential benefit of these distribution maps to marine management and planning is discussed.     

Nursery use patterns of commercially important marine fish species in estuarine systems along the Portuguese coast

Analysing the estuarine use patterns of juveniles of marine migrant fish species is vital for identifying important sites for juveniles as well as the basic environmental features that characterize these sites for different species. This is a key aspect towards understanding nursery function. Various estuarine systems along the Portuguese coast (Minho, Douro, Ria de Aveiro, Mondego, Tejo, Sado, Mira, Ria Formosa and Guadiana) were sampled during Spring and Summer 2005 and 2006. Juveniles of commercially important marine fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax, predominantly 0-group individuals, were amongst the most abundant species and had distinct patterns of estuarine use as well as conspicuous associations with several environmental features. Juvenile occurrence and density varied amongst estuaries and sites within them, and differed with species. Sites with consistently high juvenile densities were identified as important juvenile sites (i.e. putative nursery grounds). Through generalized linear models (GLM), intra-estuarine variation in occurrence and density of each of the individual species was largely explained by environmental variables (temperature; salinity; depth; percentage of mud in the sediment; presence of seagrass; importance of intertidal areas; relative distance to estuary mouth; macrozoobenthos densities; and latitude). Decisive environmental factors defining important sites for juveniles varied depending on the system as a result of different environmental gradients, though there were common dominant features for each species regardless of the estuary considered. Analysed environmental variables in the GLM also accounted for inter-estuarine variation in species' occurrence and density. In several estuaries, the identified important juvenile sites were used by many of these species simultaneously and may be of increased value to both management and conservation. Overall, the variability in site features amongst estuaries highlighted the tolerance of these species to different available environmental conditions and provided fundamental information for future spatially explicit modelling of their distribution. This should ultimately enable the prediction of species response to habitat alterations.     

Exploring the spatial distribution patterns of South African Cape hakes using generalised additive models

We developed delta generalised additive models (GAMs) to predict the spatial distribution of different size classes of South African hakes, Merluccius capensis and M. paradoxus, using demersal trawl survey data and geographical (latitude and longitude) and environmental features (depth, temperature, bottom dissolved oxygen and sediment type). Our approach consists of fitting, for each hake size class, two independent models, a binomial GAM and a quasi-Poisson GAM, whose predictions are then combined using the delta method. Delta GAMs were validated using an iterative cross-validation procedure, and their predictions were then employed to produce distribution maps for the southern Benguela. Delta GAM predictions confirmed existing knowledge about the spatial distribution patterns of South African hakes, and brought new insights into the factors influencing the presence/absence and abundance of these species. Our GAM approach can be used to produce distribution maps for spatially explicit ecosystem models of the southern Benguela in a rigorous and objective way. Ecosystem models are critical features of the ecosystem approach to fisheries, and distribution maps constructed using our GAM approach will enable a reliable allocation of species biomasses in spatially explicit ecosystem models, which will increase trust in the spatial overlaps and, therefore, the trophic interactions predicted by these models.     

Quantifying Spatial Patterns of Intertidal Biodiversity: Is Movement Important?

Abstract.  Small-scale patterns of low-, mid- and high-shore intertidal species density, richness and abundance were systematically examined to assess the potential influence of 'mobility' on spatial community dynamics and diversity. Mobile taxa outnumbered sessile species by approximately 2:1, whereas sessile individuals were over 12 times as numerous as mobile ones over the entire study site. Patterns of density, richness and abundance differed with shore level and substratum. The results also highlighted the importance of clearly distinguishing between species density and species richness when examining spatially quantitative data. The rank order of habitats from highest to lowest species density was not the same when analysed in order of species richness. The potential for the mobile proportion of assemblages to influence small-scale diversity assessment through movement was greater at mid- and high-shore zones because the ratio of mobile species was higher and abundance (relative to the lower shore) was low. These observations might reflect the relative influence of the land–sea gradient of immersion on diversity and mobility in intertidal communities. The influence of mobile organisms on marine ecosystem function may be significant because small-scale patterns of movement are known to positively influence biodiversity. High richness paired with low abundance, however, may result in underestimating the functional role of mobile intertidal species.     

From beans to breams: how participatory workshops can contribute to marine conservation planning

Systematic conservation planning is increasingly being used in the marine environment, but the relative paucity of data on marine patterns and process still presents a problem, particularly in developing countries. For example, along the south-eastern component of the Agulhas marine bioregion of South Africa, current data regarding the habitat availability, distribution and abundance of 10 seabream species (Sparidae) were insufficient to design a regional-scale conservation plan. We report on how this data void was filled using information provided by marine resource users, managers and scientists during participatory workshops. Participants described the distribution of reefs, and then scored not only the relative abundance of each of the sparid species, but also benthic biodiversity, by arranging beans into piles on paper matrices. Reef positions were verified both by discussions within individual workshops and by subsequent comparisons of outputs among workshops. Similarly, extensive discussions provided an element of verification of relative abundance and biodiversity data. Although the free-scoring method employed in quantifying relative abundance and biodiversity meant that comparisons among workshops were problematic, this was resolved by assigning data to categories according to a simple five-level abundance index. After compiling results from all workshops, relative abundance data reflected conservation status of each species. Opinions by the participants regarding the reasons for recent declines in fish abundance tallied well with explanations from the literature. Biodiversity data were less comprehensive and more difficult to verify. Nevertheless, because participatory workshops provided relatively accurate data regarding fish abundance, were cost effective to run and generated a good level of buy-in from participants, they represent a valuable new tool for marine conservation planning.     

Limiting similarity, niche filtering and functional diversity in coastal lagoon fish communities

The fundamental idea behind the study of biodiversity patterns is the presumed connection between the shape of species assemblages and the functional ways in which they are organized, this functional organization referring to how species are related to one another, as competitors or members of a web of interactions and to how species are facing similar environmental constraints. Amongst the different facets of biodiversity, functional diversity is certainly a key for ecosystem processes in coastal areas. However, surprisingly, patterns of functional diversity have received little attention until now. After presenting a common framework linking functional diversity patterns to species coexistence theories, the aim of our study was twofold: (1) to seek assembly rules in brackish lagoon fish communities drove by functional traits. To this aim we used null models to examine the influence of two opposing forces acting on community structure: interspecific competition that might prevent the coexistence of the most similar species, and environmental filters that might result in the most similar species to coexist. (2) To seek relationships between fish functional diversity and environmental gradients, if any. Fish sampling was carried out in two coastal lagoons where stations differ considerably in terms of physicochemical parameters. Using morphological functional traits, functional diversity of fish communities was estimated using two recently published indices as well as a new proposed index. Firstly our study was not able to demonstrate a limitation of similarity in coexisting lagoon fishes due to interspecific competition. Conversely our results support the niche filtering hypothesis preventing species too dissimilar from one another to co-occur at the same station. Secondly, salinity was positively related to the functional diversity of fishes in both lagoons suggesting that within species assemblages near the channel species are less redundant than at stations far from the channel where species tend to be functionally similar (benthic and eating zooplankton).     

基于转换模式的多源数字海图融合研究

数据融合是实现多源数字地图共享利用的途径之一，从制图要素空间位置融合、地理实体分类分级编码融合、数字地图空间数据模型融合等三个方面对基于转换模式的多源数字海图融合理论和方法做出分析与探讨。     

Frequent locations of oceanic fronts as an indicator of pelagic diversity: Application to marine protected areas and renewables

Frequent locations of thermal fronts in UK shelf seas were identified using an archive of 30,000 satellite images acquired between 1999 and 2008, and applied as a proxy for pelagic diversity in the designation of Marine Protected Areas (MPAs). Networks of MPAs are required for conservation of critical marine habitats within Europe, and there are similar initiatives worldwide. Many pelagic biodiversity hotspots are related to fronts, for example cetaceans and basking sharks around the Isle of Man, Hebrides and Cornwall, and hence remote sensing can address this policy need in regions with insufficient species distribution data. This is the first study of UK Continental Shelf front locations to use a 10-year archive of full-resolution (1.1 km) AVHRR data, revealing new aspects of their spatial and seasonal variability. Frontal locations determined at sea or predicted by ocean models agreed closely with the new frequent front maps, which also identified many additional frontal zones. These front maps were among the most widely used datasets in the recommendation of UK MPAs, and would be applicable to other geographic regions and to other policy drivers such as facilitating the deployment of offshore renewable energy devices with minimal environmental impact.     

Towards High-Resolution Habitat Suitability Modeling of Vulnerable Marine Ecosystems in the Deep-Sea: Resolving Terrain Attribute Dependencies

Recent habitat suitability models used to predict the occurrence of vulnerable marine species, particularly framework building cold-water corals, have identified terrain attributes such as slope and bathymetric position index as important predictive parameters. Due to their scale-dependent nature, a realistic representation of terrain attributes is crucial for the development of reliable habitat suitability models. In this paper, three known coral areas and a noncoral control area off the west coast of Ireland were chosen to assess quantitative and distributional differences between terrain attributes derived from bathymetry grids of varying resolution and information content. Correlation analysis identified consistent changes of terrain attributes as grain size was altered. Response characteristics and dimensions depended on terrain attribute types and the dominant morphological length-scales within the study areas. The subsequent effect on habitat suitability maps was demonstrated by preliminary models generated at different grain sizes. This study demonstrates that high resolution habitat suitability models based on terrain parameters derived from multibeam generated bathymetry are required to detect many of the topographical features found in Irish waters that are associated with coral. This has implications for marine spatial planning in the deep sea. Supplemental materials are available for this article. Go to the publisher's online edition of Marine Geodesy to view the free supplemental file.     

Finding the hotspots within a biodiversity hotspot: fine‐scale biological predictions within a submarine canyon using high‐resolution acoustic mapping techniques

Submarine canyons are complex geomorphological features that have been suggested as potential hotspots for biodiversity. However, few canyons have been mapped and studied at high resolution (tens of m). In this study, the four main branches of Whittard Canyon, Northeast Atlantic, were mapped using multibeam and sidescan sonars to examine which environmental variables were most useful in predicting regions of higher biodiversity. The acoustic maps obtained were ground truthed by 13 remotely operated vehicle (ROV) video transects at depths ranging from 650 to 4000 m. Over 100 h of video were collected, and used to identify and georeference megabenthic invertebrate species present within specific areas of the canyon. Both general additive models (GAMs) and random forest (RF) were used to build predictive maps for megafaunal abundance, species richness and biodiversity. Vertical walls had the highest diversity of organisms, particularly when colonized by cold‐water corals such as Lophelia pertusa and Solenosmilia variabilis. GAMs and RF gave different predictive maps and external assessment of predictions indicated that the most adequate technique varied based on the response variable considered. By using ensemble mapping approaches, results from more than one model were combined to identify vertical walls most likely to harbour a high biodiversity of organisms or cold‐water corals. Such vertical structures were estimated to represent less than 0.1% of the canyon's surface. The approach developed provides a cost‐effective strategy to facilitate the location of rare biological communities of conservation importance and guide further sampling efforts to help ensure that appropriate monitoring can be implemented.     

Subtidal macroalgal richness,diversity and turnover,at multiple spatial scales,along the southwestern Australian coastline

Patterns of species richness are governed by processes that act at vastly different spatial scales. In the marine system of southwest Australia, macroalgal assemblage structure and richness is thought to be strongly influenced by both the Leeuwin Current, which acts at large regional spatial scales, and small-scale processes such as competition, wave disturbance and habitat heterogeneity. We examined macroalgal species richness and diversity at multiple spatial scales using a three-factor hierarchal design. Spatial extents ranged from metres (between quadrats) to many hundreds of kilometres (between regions), and the study encompassed almost 2000 km of temperate coastline. Macroalgal assemblages were highly speciose and the number, identity, and diversity of species varied considerably at all spatial scales. Small scale variability, at the scale of site or quadrat, contributed most to total variation in species richness and diversity, suggesting that small-scale processes are important drivers of ecological pattern in this system. Species richness, diversity and taxonomic distinctness increased sequentially along the coastline, from warmer to cooler waters. Small scale variability was most likely maintained by wave disturbance and habitat heterogeneity at these scales, while regional scale diversity and richness clines were attributed to the fact that most species had cool-water affinities and the southern coast of Australia is a hotspot of floral speciation and diversity. Macroalgal assemblages in southwest Australia are speciose and largely endemic, and biodiversity patterns are structured by multiple processes operating at multiple spatial scales.     

Turbidity characterizes the reproduction areas of pikeperch (Sander lucioperca (L.)) in the northern Baltic Sea

The pikeperch (Sander lucioperca (L.)) is an economically important fish species occurring in the fresh and brackish waters of Europe. To evaluate the distribution and extent of the reproduction areas in the northern Baltic Sea, a field survey was carried out in two separate coastal areas. Presence/absence data were used to develop a geographic information system (GIS)-based predictive spatial distribution model, where high resolution raster maps of the focal environmental variables and a logistic regression equation were used to predict the probability of larval occurrence. The results indicated that the pikeperch reproduction areas are located in the innermost archipelago zone where high water turbidity best explained their presence. Turbidity was related to several other variables such as fetch and depth. Contrary to our preliminary hypothesis, surface water temperatures measured during the survey had no significant effect in the model due to the low spatial variation in the measured values. Since turbidity is possible to determine by remote sensing methods, the probability maps can be cost-effectively extended to more extensive coastal areas with proper validation.