Habitat complexity can boost biodiversity by providing a wide range of niches allowing species co-existence. Baltic Sea benthic communities are characterised by low species diversity. Thus the ...occurrence of the habitat forming macroalga Fucus vesiculosus may influence benthic communities and promote diversity. Here biodiversity estimates were obtained through conventional and eDNA approaches for the benthic assemblages associated with free-living Fucus and the adjacent bare-sediment habitats at six sites from the Northern Baltic Proper and the Gulf of Finland. Free-living F. vesiculosus habitats are heterogeneous with biodiversity estimates varying considerably among sites. The additional habitat complexity provided by F. vesiculosus tended to improve taxa richness as a result of additional epifauna assemblages, although macroinfaunal taxa richness and abundance was often reduced. Consequently the complex habitats provided by free-living F. vesiculosus often improve biodiversity, yet alters the composition of assemblages in soft sediment habitats and consequential ecosystem functioning. The study emphasised the disparity in biodiversity estimates achieved when employing different biodiversity approaches. Biodiversity estimates were more similar within approaches compared to between habitat types, with each approach detecting exclusive taxa. Consequently, biodiversity estimates can benefit from a multi-approach design where both conventional and eDNA approaches are employed in complement.
•Habitat forming free-living Fucus alters the benthic community in soft sediments.•Associated benthic assemblages vary markedly among free-living Fucus populations.•Conventional and eDNA approaches display disparate biodiversity estimates.•Baltic Sea biodiversity estimates benefit from a multi-approach design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The main aims of Marine Protected Areas (MPAs) are the conservation of natural habitats and their biological resources, together with the promotion of an eco-compatible economic fruition. In ...Mediterranean MPAs, the main threats for hard bottom benthic communities come from fishing and mass tourism, in terms of boating and SCUBA diving.
The Portofino MPA (Ligurian Sea, North-western Mediterranean Sea) is one of the top diving destinations in Europe and currently hosts an average of 40,000 dives per year, which are mainly carried out along coralligenous cliffs, a habitat of European Community interest, particularly vulnerable to mechanical damages due to the fragility of its numerous calcified species.
The aim of this paper is to evaluate the effects of recreational SCUBA diving on benthic ecosystems characterised by the presence of red coral and other associated fragile species. The impact was assessed through the analysis of the biomasses of target organisms (Corallium rubrum, Leptopsammia pruvoti, Madracis pharensis, and six species of bryozoans) whose fragments were found in the sediments at the base of the cliff. The amounts of these fragments inside the detritus in highly frequented sites were significantly higher than those measured in undisturbed sites, of up to 10 times. Our data suggested a recurrent mechanical action, with also very recent breakages, as demonstrated by the occurrence of living, freshly detached organisms.
Red coral and other calcified species may be sensitive also to natural (heavy storms) and human (fishing) mechanical pressures other than diving: the characterization of these impacts in the study sites, however, indicates divers frequentation as the major contributor to the damages inflicted and suggests the need for specific management measures.
•Evaluation of SCUBA diving effects on calcified, fragile species.•Comparison among two frequented and two pristine sites in the Portofino MPA.•Impact assessed comparing specimens' abundance on cliff and in underlying sediment.•Target species fragments in sediments 10 times higher in highly frequented dive spots.•MPA management urges to find a balance between fruition and mitigation of impacts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Habitats in three Baltic Sea Chemical Warfare dumpsites were described as Deep-Sea Muddy Sands.•All investigated basins belong to so-called “benthic-deserts”.•Multidisciplinary studies have been ...performed.•Dumpsites were investigated before, during and after a Major Baltic Inflow event.•Temporary Return of benthic macrofauna was observed in one basin.
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The Baltic Sea is a severely disturbed marine ecosystem that has previously been used as a dumping ground for Chemical Warfare Agents (CW). The presence of unexploded underwater ordnance is an additional risk factor for offshore activities and an environmental risk for the natural resources of the sea. In this paper, the focus is on descriptions of the marine habitat based on the observations arising from studies linked to the CHEMSEA, MODUM and DAIMON projects. Investigated areas of Bornholm, Gotland and Gdańsk Deeps are similarly affected by the Baltic Sea eutrophication, however, at depths greater than 70m several differences in local hydrological regimes and pore-water heavy metal concentrations between those basins were observed. During the lifespan of presented studies, we were able to observe the effects of Major Baltic Inflow, that started in December 2014, on local biota and their habitats, especially in the Bornholm Deep area. Reappearance of several meiofauna taxa and one macrofauna specimen was observed approximately one year after this phenomenon, however it's ecological effects already disappeared in March 2017. According to our findings and to the EUNIS Habitat Classification, the three reviewed areas should be characterized as Deep Sea Muddy Sands, while the presence of suspicious bomb-like objects both beneath and on top of the sediments confirms their CW dumpsite status.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Gazul is the shallowest mud volcano (MV) within the Shallow Field of Fluid Expulsion (SFFE) of the northeastern Gulf of Cádiz (NE Atlantic; 300–1200 m depth). The SFFE represents an important geo- ...and biodiversity area that was designated as a Site of Community Importance under the European Habitats Directive in 2014. In this study, geological features, habitats and associated biodiversity, as well as anthropogenic impacts, were characterized at Gazul MV from underwater imagery and multibeam bathymetry. Multivariate methods using the Bray-Curtis similarity index identified six main habitats, each of which harbored a characteristic faunal assemblage that included: (1) sandy ripple bottoms typified by the actiniarian Actinauge richardi; (2) sandy, muddy, coarse sand and bioclastic bottoms dominated by the solitary coral Flabellum chunii; (3) coarse sand and bioclastic bottoms, together with soft sediments covered by scattered methane-derived authigenic carbonates (MDACs) (mixed bottoms), characterized by the echinoid Cidaris cidaris; (4) hard bottoms comprising MDACs dominated by a wide variety of sponges and gorgonians; (5) coral-rubble bottoms typified by the presence of colonial scleractinian communities dominated by Madrepora oculata; and (6) mixed bottoms characterized by the presence of a styelid ascidian. Slope and water depth were the main factors explaining assemblages’ distribution, which was also supported by the presence of MDACs such as slabs, crusts and chimneys on the seafloor, as well as by the geomorphologic diversity of Gazul MV. The results highlight Gazul MV as an eco-biologically important area harboring different vulnerable marine ecosystem (VME) elements with indicator taxa such as scleractinians, sponges, gorgonians and black corals. ROV images revealed abandoned or lost fishing gears and marine debris on the seafloor, indicating anthropogenic impacts in Gazul MV and adjacent areas. Indeed trawling fisheries activities have also been detected in Vessel Monitoring System datasets. A fishery restricted area is recommended in Gazul MV due to the occurrence of diverse VMEs and species included in different conservation directives and conventions.
•Gazul MV presents a high geomorphological variability and diversity of bottom types.•Six main epibenthic assemblages have been identified conforming habitats.•Hard bottoms of the MV edifice contain the most biodiverse assemblages.•Cold-water coral communities are dominated by Madrepora oculata.•Gazul MV harbors different vulnerable marine ecosystem elements and indicators.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bottom fishing such as trawling and dredging may pose serious risks to the seabed and benthic habitats, calling for a quantitative assessment method to evaluate the impact and guide management to ...develop mitigation measures. We provide a method to estimate the sensitivity of benthic habitats based on the longevity composition of the invertebrate community. We hypothesize that long-lived species are more sensitive to trawling mortality due to their lower pace of life (i.e., slower growth, late maturation). We analyze data from box-core and grab samples taken from 401 stations in the English Channel and southern North Sea to estimate the habitat-specific longevity composition of the benthic invertebrate community and of specific functional groups (i.e., suspension feeders and bioturbators), and examine how bottom trawling affects the longevity biomass composition. The longevity biomass composition differed between habitats governed by differences in sediment composition (gravel and mud content) and tidal bed-shear stress. The biomass proportion of long-lived species increased with gravel content and decreased with mud content and shear stress. Bioturbators had a higher median longevity than suspension feeders. Trawling, in particular by gears that penetrate the seabed >2 cm, shifted the community toward shorter-lived species. Changes from bottom trawling were highest in habitats with many long-lived species (hence increasing with gravel content, decreasing with mud content). Benthic communities in high shear stress habitats were less affected by bottom trawling. Using these relationships, we predicted the sensitivity of the benthic community from bottom trawling impact at large spatial scale (the North Sea). We derived different benthic sensitivity metrics that provide a basis to estimate indicators of trawling impact on a continuous scale for the total community and specific functional groups. In combination with high resolution data of trawling pressure, our approach can be used to monitor and assess trawling impact and seabed status at the scale of the region or broadscale habitat and to compare the environmental impact of bottom-contacting fishing gears across fisheries.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, ...technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life--SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO(2) and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO(2) and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Global coastal ecosystems are under accelerating pressure from human activities and climate change. In this study we explore a long-term time series (mostly 1990–2016) from major Norwegian rivers, ...together with coastal time series from the Norwegian Skagerrak coast. The aims are to: 1) analyse long-term trends in riverine loadings to Skagerrak, changes in coastal water quality and pelagic and benthic species composition, and 2) to describe the relationships between human drivers (eutrophication and coastal darkening) and community structure of benthic communities. Riverine discharge and transport increased by 23–85% over the time period, corresponding to a 40–78% increase in concentrations of suspended particulate material in coastal waters and reduced surface salinity, connected to the reported coastal darkening of coastal waters. There was a worsening in ecological status for hard-bottom benthic communities (0–30 m) and a reduction in the lower growth depth limit of several macroalgae species. A structural shift in the community composition from macroalgae towards increased abundance of animals was found to be related to coastal darkening and reduced eutrophication. The concentration of coastal inorganic nutrients (DIN, PO4) declined by 27–36%, in response to management efforts to reduce eutrophication in European regional seas. Results indicate that reduced eutrophication was related to increased ecological status of the deep soft-bottom community (350 m), with a reduction in opportunistic polychaetes and an increase in filter feeding bivalves. This work highlights how climate change and other human-induced changes in a boreal ecosystem intensifies land-ocean interactions, and calls for more adaptive monitoring, where traditional water quality programs and policies need to evolve iteratively as new information emerges and the major drivers of the systems change.
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•Riverine discharge and transports increased from 1990 to 2016.•Corresponding long-term increase in suspended and particulate organic matter in receiving coastal waters.•Worsening in ecological status of hard-bottom communities and reduction in lower growth depth limit for macroalgae species.•Shows how climate change can intensify land-ocean interactions with implications on potential to achieve good environmental status.•Structural shifts in hard- and soft-bottom species composition related to coastal darkening and reduced eutrophication.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We analyzed composition and variations in benthic macrofaunal communities along a transect of the entire length of the Vema-Fracture Zone on board of RV Sonne (SO-237) between December 2014 and ...January 2015 in order to test whether the Mid-Atlantic Ridge serves as a barrier limiting benthic taxon distribution in the abyssal basins on both sides of the ridge or whether the fracture zone permits the migration of species between the western and eastern abyssal Atlantic basins. The Puerto Rico Trench, much deeper than the surrounding abyssal West Atlantic, was sampled to determine whether the biodiversity of its hadal macrofauna differs from that of the abyssal Atlantic.
The composition of the macrofauna from the epibenthic sledge catches yielded a total of 21,332 invertebrates. Crustacea occurred most frequently (59%) with 12,538 individuals followed by Annelida (mostly Polychaeta) (26%) with 5491 individuals, Mollusca (7%) with 1458 individuals, Echinodermata (4%) with 778 individuals, Nematoda (2%) with 502 individuals and Chaetognatha (1%) with 152 and Porifera (1%) with 131 individuals. All other taxa occurred with overall less than ten individuals (Hemichordata, Phoronida, Priapulida, Brachiopoda, invertebrate Chordata, Echiurida, Foraminifera (here refereed to macrofaunal Komokiacea only), Chelicerata, Platyhelminthes). Within the Crustacea, Peracarida (62.6%) with 7848 individuals and Copepoda (36.1%) with 44,526 individuals were the most abundant taxa. Along the abyssal Vema-Fracture Zone macrofaunal abundances (ind./1000m2) were generally higher on the eastern side, while the highest normalized abundance value was reported in the Puerto Rico Trench at abyssal station 14-1 2313 individuals/1000m2. The lowest abundance was reported at station 11-4 with 120 ind./1000m2 located at the western side of the Vema-Fracture Zone. The number of major macrofaunal taxa (phylum, class) ranged between five (stations 12-5, 13-4 and 13-5 at hadal depths in the Puerto Rico Trench) and 14 (station 9-8) in the western abyssal basin of the Vema-Fracture Zone. Differences are seen in the distribution of Porifera at macrofaunal level between eastern and western sides of the Vema-Fracture Zone. Macrofaunal composition of the study area is compared with data from other expeditions in the Atlantic and the northwest Pacific Ocean.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
As coral reef communities change and reorganise in response to increasing disturbances, there is a growing need for understanding species regimes and their contribution to ecosystem processes. Using ...a case study on coral reefs at the epicentre of tropical marine biodiversity (North Sulawesi, Indonesia), we explored how application of different biodiversity approaches (i.e., use of major taxonomic categories, high taxonomic resolution categories and trait-based approaches) affects the detection of distinct fish and benthic communities. Our results show that using major categories fails to identify distinct coral reef regimes. We also show that monitoring of only scleractinian coral communities is insufficient to detect different benthic regimes, especially communities dominated by non-coral organisms, and that all types of benthic organisms need to be considered. We have implemented the use of a trait-based approach to study the functional diversity of whole coral reef benthic assemblages, which allowed us to detect five different community regimes, only one of which was dominated by scleractinian corals. Furthermore, by the parallel study of benthic and fish communities we provide new insights into key processes and functions that might dominate or be compromised in the different community regimes.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Non‐random community changes are becoming more frequent in many ecosystems. In coral reefs, changes towards communities dominated by other than hard corals are increasing in frequency, with severe ...impacts on ecosystem functioning and provision of ecosystem services. Although new research suggests that a variety of alternative communities (i.e. not dominated by hard corals) exist, knowledge on the global diversity and functioning of alternative coral reef benthic communities, especially those not dominated by algae, remains scattered. In this systematic review and meta‐analysis of 523 articles, we analyse the different coral reef benthic community changes reported to date and discuss the advantages and limitations of the methods used to study these changes. Furthermore, we used field cover data (1116 reefs from the ReefCheck database) to explore the biogeographic and latitudinal patterns in dominant benthic organisms. We found a mismatch between literature focus on coral‐algal changes (over half of the studies analysed) and observed global natural patterns. We identified strong biogeographic patterns, with the largest and most biodiverse biogeographic regions (Western and Central Indo‐Pacific) presenting previously overlooked soft‐coral‐dominated communities as the most abundant alternative community. Finally, we discuss the potential biases associated with methods that overlook ecologically important cryptobenthic communities and the potential of new technological advances in improving monitoring efforts. As coral reef communities inevitably and swiftly change under changing ocean conditions, there is an urgent need to better understand the distribution, dynamics as well as the ecological and societal impacts of these new communities.
In coral reefs, changes towards communities dominated by other than hard corals are increasing in frequency, with severe impacts on the ecosystems. Here, we performed a systematic review and meta‐analysis to analyse the coral reef benthic community changes reported to date and discuss the advantages and limitations of the methods used. Our results show strong biogeographic patterns, with the largest and most biodiverse biogeographic regions presenting previously overlooked soft‐coral dominated communities as the most abundant alternative (i.e. dominated by other than hard corals) community.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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