Changes In Marine Biodiversity Research Articles

Taxonomic and abundance biases affect the record of marine eukaryotic plankton communities in sediment DNA archives.

Environmental DNA (eDNA) preserved in marine sediments is increasingly being used to study past ecosystems. However, little is known about how accurately marine biodiversity is recorded in sediment eDNA archives, especially planktonic taxa. Here, we address this question by comparing eukaryotic diversity in 273 eDNA samples from three water depths and the surface sediments of 24 stations in the Nordic Seas. Analysis of 18S-V9 metabarcoding data reveals distinct eukaryotic assemblages between water and sediment eDNA. Only 40% of Amplicon Sequence Variants (ASVs) detected in water were also found in sediment eDNA. Remarkably, the ASVs shared between water and sediment accounted for 80% of total sequence reads suggesting that a large amount of plankton DNA is transported to the seafloor, predominantly from abundant phytoplankton taxa. However, not all plankton taxa were equally archived on the seafloor. The plankton DNA deposited in the sediments was dominated by diatoms and showed an underrepresentation of certain nano- and picoplankton taxa (Picozoa or Prymnesiophyceae). Our study offers the first insights into the patterns of plankton diversity recorded in sediment in relation to seasonality and spatial variability of environmental conditions in the Nordic Seas. Our results suggest that the genetic composition and structure of the plankton community vary considerably throughout the water column and differ from what accumulates in the sediment. Hence, the interpretation of sedimentary eDNA archives should take into account potential taxonomic and abundance biases when reconstructing past changes in marine biodiversity.

Temporal dynamics of climate change exposure and opportunities for global marine biodiversity

Climate change is exposing marine species to unsuitable temperatures while also creating new thermally suitable habitats of varying persistence. However, understanding how these different dynamics will unfold over time remains limited. We use yearly sea surface temperature projections to estimate temporal dynamics of thermal exposure (when temperature exceeds realised species’ thermal limits) and opportunity (when temperature at a previously unsuitable site becomes suitable) for 21,696 marine species globally until 2100. Thermal opportunities are projected to arise earlier and accumulate gradually, especially in temperate and polar regions. Thermal exposure increases later and occurs more abruptly, mainly in the tropics. Assemblages tend to show either high exposure or high opportunity, but seldom both. Strong emissions reductions reduce exposure around 100-fold whereas reductions in opportunities are halved. Globally, opportunities are projected to emerge faster than exposure until mid-century when exposure increases more rapidly under a high emissions scenario. Moreover, across emissions and dispersal scenarios, 76%-97% of opportunities are projected to persist until 2100. These results indicate thermal opportunities could be a major source of marine biodiversity change, especially in the near- and mid-term. Our work provides a framework for predicting where and when thermal changes will occur to guide monitoring efforts.

Using species distribution models only may underestimate climate change impacts on future marine biodiversity

In face of global changes, projecting and mapping biodiversity changes are of critical importance to support management and conservation measures of marine ecosystems. Despite the development of a wide variety of ecosystem models capable of integrating an increasing number of ecological processes, most projections of climate-induced changes in marine biodiversity are based on species distribution models (SDMs). These correlative models present a significant advantage when the lack of knowledge on the species physiology is counterbalanced by the availability of relevant environmental variables over the species geographical range. However, correlative SDMs neglect intra- and inter-specific interactions and thereby can lead to biased projections of changes in biodiversity distribution. To evaluate the influence of trophic interactions on projections of species richness and assemblage composition under climate change scenarios, we compared biodiversity projections derived from an ensemble of different SDMs to projections derived from a hybrid model coupling SDMs and a multispecies trophic model in the Mediterranean Sea. Our results show that accounting for trophic interactions modifies projections of future biodiversity in the Mediterranean Sea. Under the RCP8.5 scenario, SDMs tended to overestimate the gains and underestimate the losses of species richness by the end of the 21st century, with marked local differences in projections, both in terms of magnitude and trend, in some biodiversity hotspots. In both SDMs and hybrid approaches, nestedness with gains in species richness was the main pattern driving dissimilarity between present and future fish and macro-invertebrate species assemblages at the Mediterranean basin scale. However, at local scale, we highlighted some differences in the relative contribution of nestedness vs replacement in driving dissimilarity. Our results call for the development of integrated modelling tools that can mechanistically consider multiple biotic and abiotic drivers to improve projections of future marine biodiversity.

Research on Fishery Resource Assessment and Sustainable Utilization (FRASU) during 1990–2020: A bibliometric review

Fishery resource assessment and sustainable utilization (FRASU) is a topic of global concern. Although fishery resources are highly profitable, these are linked to environmental and socio-economic issues. In the context of increasing demand for fishery sustainability, fishery resource assessment is essential to support scientific fishery resource management. Bibliometric techniques and the Web of Science (WOS) database from 1990 to 2020 were employed to analyse the journals, authors, institutions, countries, cited references, and keywords using the CiteSpace (5.3. R11) software and standard bibliometric indicators. A quantitative review of global research related to FRASU identified recent important research topics and allowed prediction of research trends, as well as confirmed that it is an increasing area of concern. A total of 1631 publications were retrieved from 1990 to 2020, and the most active journals, countries, authors and institutions in the field were identified. 'Fisheries Research', 'Ocean Coastal Management' and 'ICES Journal of Marine Science' are the main journals that publish FRASU research. European and North American countries are the main publishers in this field, while the contribution of Asian countries has gradually increased. It is expected that China, Japan, Brazil, and India will make increasingly significant contributions to this field. Groupers, size, catch-per-unit-effort and genetic diversity are important core research areas in this field. Policy, maximum sustainable yield, small scale fisheries, ecosystem management and sustainability frameworks are identified as potential emerging research areas. Furthermore, five key areas of current research trends on FRASU were identified: problems with fishery resource assessment, impact of changes in marine biodiversity on ecosystem services, influence of fishery resource changes on the structure of food webs, ecosystem-based fishery management, and frameworks for sustainable development of fishery resources. The findings from this bibliometric study provide insight into in the growth of research publications and changes in hot areas in the field of FRASU over the past 30 years, including global trends in emerging areas of research.

Spatial and temporal variability of the zooplankton community in Valdés Biosphere Reserve, Patagonia, Argentina: Nuevo Gulf case study

Zooplankton diversity has been identified as one of the biological Essential Ocean Variables to detect temporal and spatial changes in marine biodiversity and ecosystem health. The present study evaluated the mesozooplankton community composition and abundance associated with oceanographic variables in Nuevo Gulf (NG, 42° 42′S, 64° 30′W), a World Heritage Site in Argentinian Patagonia and part of the Valdés Biosphere Reserve. We found that >43% of total mesozooplankton community abundance was composed by copepods, followed by cladocerans (24%) in spring, while copepods represented more than 98% in summer. Variability of the abundances in most mesozooplankton groups was associated with chlorophyll a and temperature values. Among copepods, Calanoida predominated in the community, mainly reflecting high densities of Ctenocalanus vanus, especially in summer. In addition, we report for the first time the presence of the copepod Drepanopus forcipatus in this Gulf. Zooplankton information for this region is scarce and fragmented, thus a short review of previous mesozooplankton studies from nearby areas is included for context. Our work emphasizes the importance of continuous and long-term monitoring to better understand the zooplankton community under expected environmental changes.

Time-Varying Epipelagic Community Seascapes: Assessing and Predicting Species Composition in the Northeastern Pacific Ocean

The vast spatial extent of the ocean presents a major challenge for monitoring changes in marine biodiversity and connecting those changes to management practices. Remote-sensing offers promise for overcoming this problem in a cost-effective, tractable way, but requires interdisciplinary expertise to identify robust approaches. In this study, we use generalized additive mixed models to evaluate the relationship between an epipelagic fish community in the Northeastern Pacific Ocean and oceanographic predictor variables, quantified in situ as well as via remote-sensing. We demonstrate the utility of using MODIS Rrs555 fields at monthly and interannual timescales to better understand how freshwater input into the Northern California Current region affects higher trophic level biology. These relationships also allow us to identify a gradient in community composition characteristic of warmer, offshore areas and cooler, nearshore areas over the period 2003–2012, and predict community characteristics outside of sampled species data from 2013 to 2015. These spatial maps therefore represent a new, temporally and spatially explicit index of community differences, potentially useful for filling gaps in regional ecosystem status reports and is germane to the broader ecosystem-based fisheries management context.

Assessing long term change of Fucus spp. communities in the northern Baltic Sea using monitoring data and spatial modeling

Changes in nutrient and sediment concentrations alter the light availability on the seafloor, and consequently the aquatic ecosystems. Decreasing light availability limits plant growth and causes changes in species composition. Local changes in marine biodiversity caused by human activities have been documented around the Baltic Sea, but large-scale changes in species’ spatial distributions remain unreported due to a lack of data and methodological solutions. The available monitoring data of the underwater nature and the new applications for the modeling of species distribution has enabled the evaluation of past environmental conditions. We have utilized two separate analysis processes with separate datasets to assess the reduction of suitable seafloor areas for Fucus spp. in the Northern Baltic Sea. The change in depth distribution of Fucus spp. was first analyzed using monitoring data for the lower growth limit of Fucus vesiculosus from 70 monitoring stations along the Finnish coast; the measurements were taken between 1936 and 2017. The second analysis was performed by modeling the current and past favorable seafloor areas for a Fucus spp. dominated biotope. Using Secchi depth data from the early 20th century to the present day, we created a spatial variable, which represents light availability on the seafloor for over a century. The analysis results of the measurements and modeling reveal a dramatic decrease of suitable seafloor for Fucus spp.. Site by site evaluation of F. vesiculosus lower growth limit shows a strong reduction when comparing older measurements from literature sources to more recent monitoring. The change in the lower growth limit was evaluated using the methodologies of the International Union for Conservation of Nature (IUCN) and Water Framework Directive (WFD) with results indicating severe degradation and a negative development towards a collapsed state. The observed long term trend could result in the habitat reaching a collapsed state within 10–15 years. Modeling results derived with the centennial Secchi data indicate on average that the decrease in light availability has reduced favorable sea floor areas for the Fucus spp. dominated biotope by 45%. Even though the Fucus spp. dominated biotope is still relatively common along the Finnish coastal areas, the drastic scale of change makes it a threatened species group.

The MacKinnon Lists Technique: An efficient new method for rapidly assessing biodiversity and species abundance ranks in the marine environment.

Widespread and ever-increasing anthropogenic impacts in the marine environment are driving a need to develop more efficient survey methods for monitoring changes in marine biodiversity. There is a particular urgent need for survey methods that could more rapidly and effectively detect change in species richness, abundance and community composition. Here, test the suitability of the Mackinnon Lists Technique for use in the marine environment by testing its effectiveness for rapid assessment of fish communities. The MacKinnon Lists Technique is a time-efficient and cost-effective sampling method developed for studying avian tropical biodiversity, in which several list samples of species can be collected from a single survey. Using the well-established MaxN approach on data from deployments of a Baited Remote Underwater Video Systems for comparison, we tested the suitability of the MacKinnon Lists Technique for use in marine environments by analysing tropical reef fish communities. Using both methods for each data set, differences in community composition between depths and levels of protection were assessed. Both methods were comparable for diversity and evenness indices with similar ranks for species. Multivariate analysis showed that the MacKinnon Lists Technique and MaxN detected similar differences in community composition at different depths and protection status. However, the MacKinnon Lists Technique detected significant differences between factors when fewer videos (representing reduced survey effort) were used. We conclude that the MacKinnon Lists Technique is at least as effective as the widely used MaxN method for detecting differences between communities in the marine environment and suggest can do so with lower survey effort. The MacKinnon Lists Technique has the potential to be widely used as an effective new tool for rapid conservation monitoring in marine ecosystems.

Challenges for global ocean observation: the need for increased human capacity

ABSTRACTSustained global ocean observations are needed to recognise, understand, and manage changes in marine biodiversity, resources and habitats, and to implement wise conservation and sustainable development strategies. To meet this need, the Global Ocean Observing System (GOOS), a network of observing systems distributed around the world and coordinated by the Intergovernmental Oceanographic Commission (IOC) has proposed Essential Ocean Variables (EOVs) that are relevant to both the scientific and the broader community, including resource managers. Building a network that is truly global requires expanding participation beyond scientists from well-resourced countries to a far broader representation of the global community. New approaches are required to provide appropriate training, and resources and technology should follow to enable the application of this training to engage meaningfully in global observing networks and in the use of the data. Investments in technical capacity fulfil international reporting obligations under the UN Sustainable Development Goal 14A. Important opportunities are emerging now for countries to develop research partnerships with the IOC and GOOS to address these obligations. Implementing these partnerships requires new funding models and initiatives that support a sustained research capacity and marine technology transfer.

Impacts of changing climate on the non-indigenous invertebrates in the northern Baltic Sea by end of the twenty-first century

Biological invasions coupled with climate change drive changes in marine biodiversity. Warming climate and changes in hydrology may either enable or hinder the spread of non-indigenous species (NIS ...

Mercury anomaly, Deccan volcanism, and the end-Cretaceous mass extinction

The contribution of the Deccan Traps (west-central India) volcanism in the Cretaceous-Paleogene (KPg) crisis is still a matter of debate. Recent U-Pb dating of zircons interbedded within the Deccan lava flows indicate that the main eruptive phase (>1.1 × 106 km3 of basalts) initiated ∼250 k.y. before and ended ∼500 k.y. after the KPg boundary. However, the global geochemical effects of Deccan volcanism in the marine sedimentary record are still poorly resolved. Here we investigate the mercury (Hg) content of the Bidart (France) section, where an interval of low magnetic susceptibility (MS) located just below the KPg boundary was hypothesized to result from paleoenvironmental perturbations linked to the paroxysmal Deccan phase 2. Results show Hg concentrations >2 orders of magnitude higher from ∼80 cm below to ∼50 cm above the KPg boundary (maximum 46.6 ppb) and coincident with the low MS interval. Increase in Hg contents shows no correlation with clay or total organic carbon contents, suggesting that the Hg anomalies resulted from higher input of atmospheric Hg species into the marine realm, rather than organic matter scavenging and/or increased runoff. The Hg anomalies correlate with high shell fragmentation and dissolution effects in planktic foraminifera, suggesting correlative changes in marine biodiversity. This discovery represents an unprecedented piece of evidence of the nature and importance of the Deccan-related environmental changes at the onset of the KPg mass extinction.

NansClim – climate effects on biodiversity, abundance and distribution of marine organisms

Human interference with the climate system is occurring, and climate change poses risks for human and natural systems (IPCC, 2014). In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Evidence of climate-change impacts is strongest and most comprehensive for natural systems. Due to climate change projected by the mid 21st century and beyond, global marine-species redistribution and marine-biodiversity reduction in sensitive regions will challenge the sustained provision of fisheries productivity and other ecosystem services (IPCC, 2014). Spatial shifts of marine species due to projected warming will cause high-latitude invasions and high local-extinction rates in the tropics and semi-enclosed seas. Species richness and fisheries catch potential are projected to increase, on average, at mid and high latitudes and decrease at tropical latitudes (IPCC, 2014). The Benguela Current Large Marine Ecosystem (BCLME) is one of four Eastern Boundary Upwelling Ecosystems (EBUE), highly productive marine subregions. Although they comprise <2% of the global ocean area, they contribute nearly 7% of marine primary production and more than 20% of the world’s marine capture fisheries (IPCC, 2014). Catches in the EBUE are dominated by planktivorous species such as sardine, anchovy, and horse/jack mackerel, and piscivorous demersal species such as hake. Upwelling of nutrient-rich water stimulates primary production which is transferred to mid and upper trophic levels, resulting in substantial fish, seabird, and marine mammal populations. As a result, EBUEs are considered ‘hotspots’ of productivity and biodiversity. Previous research on the BCLME has had little emphasis on climate change. As with the other EBUEs, strong inter-annual and inter-decadal variability in physical oceanography makes it challenging to detect biophysical trends attributed to climate change. Nevertheless, the physical conditions of the BCLME are highly sensitive to climate variability over a range of scales. Despite its apparent sensitivity to environmental variability, there is limited evidence of ecological changes in the BCLME caused by climate change (IPCC, 2014). For example, pelagic fish, benthic crustaceans, and seabirds have demonstrated general shifts in distribution (IPCC, 2014). Even though much of the evidence on the recent climate change comes from remote sensing and outputs from coupled atmosphere-ocean models, it is necessary to link the global trends with local observations to detect the effects of this change on marine living resources in a regional context. In the BCLME region, the combined oceanographic and biodiversity database collected through the Ecosystem Approach to Fisheries (EAF) Nansen Programme is potentially a major source of local data covering climate change and its effect on marine resources in the last 30 yr. However, its contributions to the understanding of climate change effects on the BCLME are rather limited so far, since the huge amount of data collected under the programme has not been fully utilised. Based on data collected through the EAF Nansen programme, together with other relevant data, the NansClim project (2009–2014) was established to identify and describe possible trends and variability in ocean climate and corresponding changes in marine biodiversity and fisheries in the Benguela Current System. Observations of effects of climate variability on marine biota in the past, based on the Nansen database in combination with other data series available from the region, allowed NansClim to document some general responses concerning production and distribution of marine biota to set a baseline of observed effects of climate variability. Some of the species in the region are more poorly studied than others, and one of the tasks of the project was therefore to characterize the life cycle of such species which may be important indicators of future climate change.

Metacommunity modelling, a fundamental approach for marine biodiversity studies

1 - Comprehensive understanding of biological diversity patterns requires quantifying spatial dynamic processes. Mathematical modelling offers an array of techniques to investigate ecosystem processes that cannot be observed directly or tested experimentally.2 - In the 1990’s, a new paradigm for biodiversity studies appeared - called metacommunities - combining ecological and biogeographical concepts of species assemblages. A metacommunity is defined as a set of local communities linked by the exchanges of individuals at the regional scale. This relatively simple definition led to the development of theoretical frameworks (e.g. emphasizing neutrality, patch dynamics, species sorting and mass effects) that generated some controversy about the relative importance of the local ecological niche-based processes and regional dispersal processes. Recent studies have demonstrated that several of these proposed theories can lead to similar results when simulating the dynamics of metacommunity systems.3 - Thus, it does not seem possible to adequately prove whether or not local processes predominate over regional ones from available datasets, even if several evaluation criteria are combined. This is why metacommunity modelling is an important step toward quantifying changes in marine biodiversity. Models can be improved by unifying population dynamics processes and by establishing accurate typologies of parameter estimates. Validation should be performed by carrying out ad hoc experiments, testing dynamic properties; however, the design and implementation of these experiments remain difficult because of the lack of large-scale experimental facilities under controlled conditions.4 - Metacommunity modelling seems however to be promising for a broad range of applications in the domain of conservation of marine biodiversity, and particularly in that it can provide objective criteria to define Marine Protected Areas as a function of regional biodiversity conservation goals.

Status of Marine Biodiversity of the China Seas

China's seas cover nearly 5 million square kilometers extending from the tropical to the temperate climate zones and bordering on 32,000 km of coastline, including islands. Comprehensive systematic study of the marine biodiversity within this region began in the early 1950s with the establishment of the Qingdao Marine Biological Laboratory of the Chinese Academy of Sciences. Since that time scientists have carried out intensive multidisciplinary research on marine life in the China seas and have recorded 22,629 species belonging to 46 phyla. The marine flora and fauna of the China seas are characterized by high biodiversity, including tropical and subtropical elements of the Indo-West Pacific warm-water fauna in the South and East China seas, and temperate elements of North Pacific temperate fauna mainly in the Yellow Sea. The southern South China Sea fauna is characterized by typical tropical elements paralleled with the Philippine-New Guinea-Indonesia Coral triangle typical tropical faunal center.This paper summarizes advances in studies of marine biodiversity in China's seas and discusses current research mainly on characteristics and changes in marine biodiversity, including the monitoring, assessment, and conservation of endangered species and particularly the strengthening of effective management. Studies of (1) a tidal flat in a semi-enclosed embayment, (2) the impact of global climate change on a cold-water ecosystem, (3) coral reefs of Hainan Island and Xisha-Nansha atolls, (4) mangrove forests of the South China Sea, (5) a threatened seagrass field, and (6) an example of stock enhancement practices of the Chinese shrimp fishery are briefly introduced. Besides the overexploitation of living resources (more than 12.4 million tons yielded in 2007), the major threat to the biodiversity of the China seas is environmental deterioration (pollution, coastal construction), particularly in the brackish waters of estuarine environments, which are characterized by high productivity and represent spawning and nursery areas for several economically important species. In the long term, climate change is also a major threat. Finally, challenges in marine biodiversity studies are briefly discussed along with suggestions to strengthen the field. Since 2004, China has participated in the Census of Marine Life, through which advances in the study of zooplankton and zoobenthos biodiversity were finally summarized.

Structural and functional vulnerability to elevated pCO2 in marine benthic communities

The effect of elevated pCO2/low pH on marine invertebrate benthic biodiversity, community structure and selected functional responses which underpin ecosystem services (such as community production and calcification) was tested in a medium-term (30 days) mesocosm experiment in June 2010. Standardised intertidal macrobenthic communities, collected (50.3567°N, 4.1277°W) using artificial substrate units (ASUs), were exposed to one of seven pH treatments (8.05, 7.8. 7.6, 7.4, 7.2, 6.8 and 6.0). Community net calcification/dissolution rates, as well as changes in biomass, community structure and diversity, were measured at the end of the experimental period. Communities showed significant changes in structure and reduced diversity in response to reduced pH: shifting from a community dominated by calcareous organisms to one dominated by non-calcareous organisms around either pH 7.2 (number of individuals and species) or pH 7.8 (biomass). These results were supported by a reduced total weight of CaCO3 structures in all major taxa at lowered pH and a switch from net calcification to net dissolution around pH 7.4 (Ωcalc = 0.78, Ωara = 0.5). Overall community soft tissue biomass did not change with pH and high mortality was observed only at pH 6.0, although molluscs and arthropods showed significant decreases in soft tissue. This study supports and refines previous findings on how elevated pCO2 can induce changes in marine biodiversity, underlined by differential vulnerability of different phyla. In addition, it shows significant elevated pCO2-/low pH-dependent changes in fundamental community functional responses underpinning changes in ecosystem services.

Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities

A mesocosm experiment was conducted to quantify the effects of reduced pH and elevated temperature on an intact marine invertebrate community. Standardised faunal communities, collected from the extreme low intertidal zone using artificial substrate units, were exposed to one of eight nominal treatments (four pH levels: 8.0, 7.7, 7.3 and 6.7, crossed with two temperature levels: 12 and 16°C). After 60 days exposure communities showed significant changes in structure and lower diversity in response to reduced pH. The response to temperature was more complex. At higher pH levels (8.0 and 7.7) elevated temperature treatments contained higher species abundances and diversity than the lower temperature treatments. In contrast, at lower pH levels (7.3 and 6.7), elevated temperature treatments had lower species abundances and diversity than lower temperature treatments. The species losses responsible for these changes in community structure and diversity were not randomly distributed across the different phyla examined. Molluscs showed the greatest reduction in abundance and diversity in response to low pH and elevated temperature, whilst annelid abundance and diversity was mostly unaffected by low pH and was higher at the elevated temperature. The arthropod response was between these two extremes with moderately reduced abundance and diversity at low pH and elevated temperature. Nematode abundance increased in response to low pH and elevated temperature, probably due to the reduction of ecological constraints, such as predation and competition, caused by a decrease in macrofaunal abundance. This community‐based mesocosm study supports previous suggestions, based on observations of direct physiological impacts, that ocean acidification induced changes in marine biodiversity will be driven by differential vulnerability within and between different taxonomical groups. This study also illustrates the importance of considering indirect effects that occur within multispecies assemblages when attempting to predict the consequences of ocean acidification and global warming on marine communities.

Direct effects of climate change on the Antarctic krill fishery

Climate change is predicted to affect marine fisheries, but these effects are usually considered to be indirect, for example through distributional changes in fish populations (Perry, Low, Ellis & Reynolds 2005), changes in marine biodiversity (Cheung, Lam, Sarmiento, Kearney, Watson & Pauly 2009) or changes in oceanic productivity (Sharp 2003). This article shows that in Antarctic waters, there is already evidence of direct effects of the changing physical environment – the duration of sea ice cover – on the seasonal behaviour of the region's largest fishery, that for Antarctic krill, Euphausia superba (Kock, Reid,Croxall & Nicol 2007). Declining sea ice cover in the main krill fishing grounds has resulted in greater accessibility of krill stocks to the fishing fleets, particularly during winter, and this change in fishing behaviour will need careful management in an era of rapid ecological change.

Large-scale studies of the European benthos: the MacroBen database

CONTENTS ABSTRACT: Within the European Network of Excellence (NoE) on Marine Biodiversity and Ecosystem Functioning (MarBEF), marine biodiversity scientists from across Europe have been brought together to focus on 3 broad themes. Theme 1 describes large-scale (and long-term) distribution patterns of marine biodiversity, Theme 2 examines the consequences of changes in marine biodiversity for the functioning of marine ecosystems, and Theme 3 explores and disseminates the socio-economic consequences of changes in marine biodiversity and biodiversity-mediated processes. Within MarBEF Theme 1, a large col- laborative effort has produced an integrated database of species occurrence information (MacroBen), which contains data of quantitative samples of soft-sediment benthic infauna collected in European con- tinental waters, from the Arctic to the Black Sea. Papers in this Theme Section describe initial studies based on the database. The late Prof. John S. Gray led activities within MarBEF Theme 1 for the first 2.5 yr, during which time the majority of the work described in this Theme Section was set in motion, and he continued to be involved in the work until his untimely death. We dedicate this body of work to his memory.

Jurassic transgressions and regressions in the Caucasus (northern Neotethys Ocean) and their influences on the marine biodiversity

In the Jurassic, the Caucasus, presently located in the southwest of Russia, Georgia, Armenia and Azerbaijan, was located on the northern active margin of the Neotethys Ocean. Facies interpretation in all 62 areas, distinguished by differences in facies, allows to semi-quantitatively evaluate Jurassic regional transgressions and regressions for this region. Major transgressive regressive cycles took place in the Hettangian–Aalenian, Bajocian–Bathonian and Callovian–Tithonian. Each transgression was more extensive than the previous. The same cycles are established in the Greater Caucasus Basin. Deep-marine environments were common in the Pliensbachian, late Aalenian and late Bathonian, whereas they were very restricted in the Late Jurassic. The Jurassic transgressions and regressions in the Caucasus coincided with the proposed global eustatic changes. However, some differences were caused by the regional tectonic activity. Although transgressions and regressions cause some changes in marine biodiversity, it seems that only ammonites might have been directly influenced by them. Diversity of bivalves, brachiopods and belemnites was driven by other factors. However, global changes in marine biodiversity were more closely related to the eustatic fluctuations than it was documented on a regional scale.

Phanerozoic marine biodiversity follows a hyperbolic trend

Changes in marine biodiversity through the Phanerozoic correlate much better with hyperbolic model (widely used in demography and macrosociology) than with exponential and logistic models (traditionally used in population biology and extensively applied to fossil biodiversity as well). The latter models imply that changes in diversity are guided by a first-order positive feedback (more ancestors, more descendants) and/or a negative feedback arising from resource limitation. Hyperbolic model implies a second-order positive feedback. The hyperbolic pattern of the world population growth arises from a second-order positive feedback between the population size and the rate of technological growth. The hyperbolic character of biodiversity growth can be similarly accounted for by a feedback between the diversity and community structure complexity. The similarity between the curves of biodiversity and human population probably comes from the fact that both are derived from the interference of the hyperbolic trend with cyclical and stochastic dynamics.