The ecological causes of functional distinctiveness in communities

Recent work has shown that evaluating functional trait distinctiveness, the average trait distance of a species to other species in a community offers promising insights into biodiversity dynamics and ecosystem functioning. However, the ecological mechanisms underlying the emergence and persistence of functionally distinct species are poorly understood. Here, we address the issue by considering a heterogeneous fitness landscape whereby functional dimensions encompass peaks representing trait combinations yielding positive population growth rates in a community. We identify four ecological cases contributing to the emergence and persistence of functionally distinct species. First, environmental heterogeneity or alternative phenotypic designs can drive positive population growth of functionally distinct species. Second, sink populations with negative population growth can deviate from local fitness peaks and be functionally distinct. Third, species found at the margin of the fitness landscape can persist but be functionally distinct. Fourth, biotic interactions (positive or negative) can dynamically alter the fitness landscape. We offer examples of these four cases and guidelines to distinguish between them. In addition to these deterministic processes, we explore how stochastic dispersal limitation can yield functional distinctiveness. Our framework offers a novel perspective on the relationship between fitness landscape heterogeneity and the functional composition of ecological assemblages

International Bottom Trawl Survey Working Group (IBTSWG). ICES Scientific Reports, 04:65

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examina-tion of changes in fish distribution and relative abundance. The group also promotes the stand-ardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG

Are we ready to track climate-driven shifts in marine species across international boundaries? - A global survey of scientific bottom trawl data

Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio-temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate-driven ocean changes.En prensa6,86

Cross-basin and cross-taxa patterns of marine community tropicalization and deborealization in warming European seas.

Ocean warming and acidification, decreases in dissolved oxygen concentrations, and changes in primary production are causing an unprecedented global redistribution of marine life. The identification of underlying ecological processes underpinning marine species turnover, particularly the prevalence of increases of warm-water species or declines of cold-water species, has been recently debated in the context of ocean warming. Here, we track changes in the mean thermal affinity of marine communities across European seas by calculating the Community Temperature Index for 65 biodiversity time series collected over four decades and containing 1,817 species from different communities (zooplankton, coastal benthos, pelagic and demersal invertebrates and fish). We show that most communities and sites have clearly responded to ongoing ocean warming via abundance increases of warm-water species (tropicalization, 54%) and decreases of cold-water species (deborealization, 18%). Tropicalization dominated Atlantic sites compared to semi-enclosed basins such as the Mediterranean and Baltic Seas, probably due to physical barrier constraints to connectivity and species colonization. Semi-enclosed basins appeared to be particularly vulnerable to ocean warming, experiencing the fastest rates of warming and biodiversity loss through deborealization

Integration and sharing of data on marine ecosystems.

Integration and data sharing on marine ecosystem constitute two major contributors to ecosystem management. In this report, we present the different methods that have been used to integrate and share data in the context of Interreg IVA France (Channel) – England projects. Identification of limits and barriers encountered within these projects may help to improve our capacity to lead future projects, notably those involved in marine ecosystem management.L’intégration et le partage des données constituent deux étapes majeures de la gestion de l’écosystème. Nous présentons ici les différentes méthodes d’intégration et de partage des données exploitées dans le contexte des projets Interreg IVA France (Manche) - Angleterre. L’identification des différentes limites ou obstacles rencontrés au sein de ces projets peut améliorer notre capacité à diriger les futurs projets, notamment ceux qui contribuent à la gestion des écosystèmes marins

Ecological and life history traits explain a climate induced shift in a temperate marine fish community

A better understanding of community dynamics and ecosystem functioning can be achieved by describing how community functional structure responds to environmental change over both time and space and by identifying which functional groups best mediate community responses. Here, we used a trait-based approach in combination with a newly developed application of principal response curves to functionally characterize a rapid taxonomic shift in the eastern English Channel fish community in the late 1990s. We identified the functional groups with the greatest contributions to the overall shift in fish functional structure and uncovered significant trait−environment relationships. We found that pelagic species with rapid life history cycles, characterized by broadcast spawning, small offspring size, and early maturation, declined considerably in abundance following an increase in sea surface temperature associated with a warming phase of the Atlantic Multidecadal Oscillation, which was likely exacerbated by historical fishing pressure. In contrast, species with late maturation, high parental care, and few, well-developed offspring increased in abundance, reinforcing that fish community responses to climate warming are strongly mediated through life history traits. By examining how environmental factors drove a community shift at the trait level, we provide a mechanistic understanding of how fish functional structure responds to rapid environmental change

International Bottom Trawl Survey (IBTS2021-Q1) - French cruise report.

In 2021, the French NS-IBTS Q1 survey was conducted as part of the International Bottom Trawl Survey program carried out by main countries bordering the North Sea in order to assess abundance and stocks distribution, independently of commercial fisheries data. The first target of the NS-IBTS Q1 survey is to provide a diagnosis on the main commercial fish species by estimating their abundance per age. A standardized protocol is rigorously applied by all participants. The R/V Thalassa sampled the eastern part of the Channel and southern North Sea (until 56° N) from 19th January to 9th February 2021. During daily time, 56 hauls, lasting 30 minutes, have been carried out with a GOV bottom trawl. A total of 82 fish species have been collected, determined and measured, and 2605 otoliths (for age estimation) have been collected for 13 species. This year, whiting (Merlangius merlangus) represented 30% of the total biomass caught followed by herring (Clupea harengus, 26%). During the night, 107 MIK net have been deployed to calculate an index for herring and sprat larvae abundance. Within each station, a CTD sensor was deployed to record environmental parameters (e.g., temperature, salinity and oxygen) all along the water column, from surface to bottom. In order to study the whole marine ecosystem, some additional studies were carried out in the context of the Marine Strategy Framework Strategy and for various research projects

International Bottom Trawl Survey (IBTS2019-Q1). French cruise report

IBTS surveys (International Bottom Trawl Survey) are carried out within an international framework. Main countries bordering the North Sea participate to it according to the European Community regulations (EC N°1543/2000 and N° 1639/2001) which specify that countries from E.U. have to carry out surveys at sea in order to evaluate abundance and stocks distribution, independently of commercial fisheries data. The first target of the IBTS survey is to have a diagnosis on the main commercial fish stock and to calculate abundances index by age for these species. This survey started in the years 70’s and gradually standardised. Since the years 80’s, a common protocol is implemented and used by all participants. The same fishing gear and the same working methods are used. In addition, to calculate an index for herring and sprat larvae (0 groups), each participating vessel operates with a MIK net during the night (Methot Isaac Kidd). For 20 years, the southern part of the North Sea has been allocated to the French vessel and since 2007, the Eastern Channel has been integrated to the whole sampled area. As interactions and circulation of stock between these two areas are important, Eastern Channel is often associated the North Sea for stock assessment. Herring for example which is exploited all the year in the North Sea comes into the Channel during November and December for reproduction. More precise information on larvae indices will be obtained when this area is sampled. In order to study the whole marine ecosystem of the North Sea and English Channel, some additional studies are carried out during the Survey on the R/V Thalassa. For example, the Continuous Underwater Fish Eggs Sampler device (CUFES) is used to study fish spawning areas. Abundance and distribution of the winter planktonic community (phyto and zoo plankton) and a monitoring study on the structure and distribution of the benthic macroinvertebrates community are also carried out. At last, more samples are done for the Marine Strategy framework since 2015

International Bottom Trawl Survey (IBTS2020-Q1). French cruise report

IBTS surveys (International Bottom Trawl Survey) are carried out within an international framework. Main countries bordering the North Sea participate to it according to the European Community regulations (EC N°1543/2000 and N° 1639/2001) which specify that countries from E.U. have to carry out surveys at sea in order to evaluate abundance and stocks distribution, independently of commercial fisheries data. The first target of the IBTS survey is to have a diagnosis on the main commercial fish stock and to calculate abundances index by age for these species. This survey started in the years 70’s and gradually standardised. Since the years 80’s, a common protocol is implemented and used by all participants. The same fishing gear and the same working methods are used. In addition, to calculate an index for herring and sprat larvae (0 groups), each participating vessel operates with a MIK net during the night (Methot Isaac Kidd). For 20 years, the southern part of the North Sea has been allocated to the French vessel and since 2007, the Eastern Channel has been integrated to the whole sampled area. As interactions and circulation of stock between these two areas are important, Eastern Channel is often associated the North Sea for stock assessment. Herring for example which is exploited all the year in the North Sea comes into the Channel during November and December for reproduction. More precise information on larvae indices will be obtained when this area is sampled. In order to study the whole marine ecosystem of the North Sea and English Channel, some additional studies are carried out during the Survey on the R/V Thalassa. For example, the Continuous Underwater Fish Eggs Sampler device (CUFES) is used to study fish spawning areas. Abundance and distribution of the winter planktonic community (phyto and zoo plankton) and a monitoring study on the structure and distribution of the benthic macroinvertebrates community are also carried out. At last, more samples are done for the Marine Strategy framework since 2015