Offshore Communities Research Articles

Diversity, distribution and knowledge gaps of Polychaeta on the continental shelf of southern Namibia

This study investigated the diversity, composition and distribution patterns of polychaete macrofauna inhabiting unconsolidated sediments on the continental shelf of southern Namibia. During the austral summer of 2021, 910 Van Veen grab samples were collected from 91 sites in water depths ranging between 43 and 146 m. All benthic macrofauna (> 1 mm) were extracted, identified, enumerated and weighed. Polychaetes were the most abundant taxon, equating to 66% of total abundance and 37% of total biomass. A total of 83 712 polychaete specimens comprising 112 species, 80 genera and 33 families were collected. Several taxa identified were listed as putative cosmopolitans (19 taxa) or have known wide local distributions (10 taxa). Voucher specimens were collected for DNA barcoding to improve reference sequence libraries for the region. Hierarchical cluster analyses using both abundance and biomass data were undertaken to determine spatial distribution patterns in polychaete communities. Both datasets yielded similar results with polychaete assemblages divided into inshore and offshore communities, that were further subdivided at a local scale. Investigation of physical and chemical drivers suggested that polychaete communities in southern Namibia are structured to varying degrees by water depth, latitude, sediment composition, redox potential and organic content. Deeper stations comprised the highest diversity of polychaeta fauna. Species adapted to hypoxic conditions (e.g. Sigambra parva, Pararionospio pinnata, Diopatra cf. monroi and Nepthys cf. hombergii) dominated an area known as the mudbelt, where organically enriched silts and clays originating from the Orange River are deposited on the mid-shelf between the 40 and 120 m isobaths.

The Adoption of AISC 360 for Offshore Structural Design Practices

The offshore design standards for U.S. practices refer to AISC specifications when designing structural components with nontubular shapes. The widely used API RP-2A WSD standard (API, 2014) asks designers to use the 1989 AISC Specification. The newly published API RP-2A LRFD and RP-2TOP ask designers to use the 2010 AISC Specification. Although the 2010 AISC Specification has been partially adopted by API, the current offshore practice is still primarily dominated by the 1989 AISC Specification. The key issue hampering the offshore community’s full adoption of the 2010 AISC Specification is the relative ease of accounting for second-order effects in the 1989 AISC Specification. In 2019, API formed a Task Group dedicated to studying this issue, with the main findings summarized in this paper. By illustrating the key code check process in two examples with an easy-to-understand format, this paper aims to assist offshore structural engineers to better understand the latest AISC specification. The authors also hope that this paper will serve as a communication path between the offshore structural community and AISC for current and future standards’ adoption and harmonization.

Distinct Assembly Processes Structure Planktonic Bacterial Communities Among Near- and Offshore Ecosystems in the Yangtze River Estuary

The estuarine system functions as natural filters due to its ability to facilitate material transformation, planktonic bacteria play a crucial role in the cycling of complex nutrients and pollutants within estuaries, and understanding the community composition and assembly therein is crucial for comprehending bacterial ecology within estuaries. Despite extensive investigations into the composition and community assembly of two bacterial fractions (free-living, FLB; particle-attached, PAB), the process by which bacterioplankton communities in these two habitats assemble in the nearshore and offshore zones of estuarine ecosystems remains poorly understood. In this study, we conducted sampling in the Yangtze River Estuary (YRE) to investigate potential variations in the composition and community assembly of FLB and PAB in nearshore and offshore regions. We collected 90 samples of surface, middle, and bottom water from 16 sampling stations and performed 16S rRNA gene amplicon analysis along with environmental factor measurements. The results unveiled that the nearshore communities demonstrated significantly greater species richness and Chao1 indices compared to the offshore communities. In contrast, the nearshore communities had lower values of Shannon and Simpson indices. When compared to the FLB, the PAB exhibit a higher level of biodiversity and abundance. However, no distinct alpha and beta diversity differences were observed between the bottom, middle, and surface water layers. The community assembly analysis indicated that nearshore communities are predominantly shaped by deterministic processes, particularly due to heterogeneous selection of PAB; In contrast, offshore communities are governed more by stochastic processes, largely due to homogenizing dispersal of FLB. Consequently, the findings of this study demonstrate that nearshore and PAB communities exhibit higher levels of species diversity, while stochastic and deterministic processes exert distinct influences on communities among near- and offshore regions. This study further sheds new light on our understanding of the mechanisms governing bacterial communities in estuarine ecosystems.

Lake Ontario’s nearshore zooplankton: Community composition changes and comparisons to the offshore

In large lake systems the nearshore habitat is an intermediate zone between the shoreline and offshore, is an important nursery for larval fish, and is highlighted as an area in need of research in the Laurentian Great Lakes. In this study, we used two long-term monitoring programs to characterize the nearshore zooplankton community composition using seasonal data (May – October) and to compare the nearshore and offshore zooplankton community composition changes over time (1998 – 2019) to determine if the changes were synchronized. In the nearshore, we found the highest zooplankton biomass during the late summer/early fall (August 27th – Oct 6th), compared to mid-summer (July 1st – Aug 26th) and late spring (May 20th – June 30th). In the summer, the nearshore zooplankton community was dominated by cladocerans while copepods dominated the offshore community. From 1998 to 2019, both nearshore and offshore copepods shifted from a cyclopoid to a calanoid-dominated state, but the details of this change were different. For example, taxon-specific analysis revealed that despite reduced cyclopoids in both habitats, Mesocyclops edax increased in the nearshore. Additionally, taxon-specific analysis suggested the changes occurred an average of three years earlier in the nearshore. Using Analysis of Similarity, the nearshore and offshore summer zooplankton community compositions became increasingly distinct over time. Results from this study highlight the uniqueness of the nearshore in large lake systems, the importance of seasonal and long-term monitoring, and the potential of the nearshore as an early indicator of offshore changes.

Mediterranean onshore–offshore gradient in the composition and temporal turnover of benthic molluscs across the middle Piacenzian Warm Period

Abstract The mid-Piacenzian Warm Period (mPWP: 3.3–3.0 Ma) is the most recent geological analogue of ongoing climate change and has been the subject of considerable interest for numerical models of the climate system. To verify the effect of the mPWP on diversity and temporal turnover of marine benthic communities, we evaluated changes in species-level abundance and the composition of Mediterranean Pliocene molluscs prior, during and after the mPWP. The Pliocene onshore–offshore gradient in species composition did not change during the mPWP (and continued basically unchanged up to the present day in the Mediterranean Sea), with most dominant species occupying the same rank in a given environment. During the mPWP, species evenness generally increased towards offshore environments. Within the three time intervals, temporal similarity is greater in offshore environments, except during the mPWP when offshore communities also exhibited greater dissimilarity. The temporal turnover in composition decreased again with depth as global temperatures decreased after the mPWP. The structure of mPWP communities suggests that warming and sea-level rise contributed to the expansion of vegetated bottoms (onshore) and shelly and coralligenous bottoms (offshore). Although the effects of mPWP warming did not change the onshore–offshore gradient in the long term, its effect disproportionately affected deeper environments, in contrast to colder climate regimes.

Can microplastics in offshore waters reflect plastic emissions from coastal regions?

Marine microplastic pollution is a major environmental challenge that threatens marine ecosystems and human health. Several models have been used to calculate and predict the theoretical amount of plastic waste discharged into the sea by coastal countries. Unlike earlier theoretical models of source discharge, we used the method of data normalisation to focus on the actual distribution of microplastics and their potential ecological risk in offshore surface waters. Our findings indicate that the average normalised abundance of microplastics in near-shore region of Bohai Sea was greater than the average normalised abundance of microplastics in the seas near the Yangtze River Delta urban agglomeration and the Pearl River Delta urban agglomeration. Moreover, the average amount of plastic waste discharged from terrestrial sources to the ocean per kilometre exhibited the following order: Bohai Rim urban agglomeration (150.90) (tonnes km−1) < the Pearl River Delta urban agglomeration (274.30) (tonnes km−1) < Yangtze River Delta urban agglomeration (577.44) (tonnes km−1). Further, the average microplastics abundance in offshore areas of different countries and the amount of plastic discharged per kilometre of the coastline were significantly negatively correlated, implying that microplastics were not necessarily abundant in coastal areas where large amounts of plastic are discharged into the sea. Hydrodynamic conditions had the greatest influence on the distribution of microplastics in offshore surface waters. The transport of nutrient salts from terrestrial areas to offshore waters was also influenced by hydrodynamics, with enrichment patterns in offshore areas exhibiting similar to those of microplastics. Therefore, when the offshore microplastic accumulation area overlapped with the nutrient salt enrichment zone, the health risk associated with the consumption of edible fish from offshore communities increased. In view of these findings, coastal countries must implement policies to reduce marine plastic waste emissions and develop management strategies based on their local pollution levels.

Spatial and temporal distribution of mesozooplankton in the coastal waters of Cyprus (Eastern Mediterranean)

This study provides elements on the spatial and temporal mesozooplankton variability during a three-year study, encompassing vertical hauls from 50 m deep to the surface from four coastal locations of Cyprus. The total mesozooplankton abundance fluctuated between 190.4 and 882.5 individuals m-3. A total of 90 holoplanktonic and meroplanktonic taxa were recorded. Copepods dominated in the community and accounted for 71.7% of the total mesozooplankton, followed by appendicularians, molluscs, cladocerans, and siphonophores, which contributed 8.04%, 5.48%, 4.60%, and 3.31%, respectively. There were no statistically significant differences among the four sampling sites for any of the mesozooplanktonic taxa, though seasonal and interannual differences were recorded for several of them. The community composition reinforced the evidence for a higher resemblance of the Cyprus mesozooplankton to the offshore communities of the northern and central Levantine Sea and those around Rhodes Island, instead of the northeastern Mediterranean coastal areas. Comparisons of the seasonal abundance variation of the mesozooplankton taxa with other coastal areas of the Levantine Sea are provided. Considering the seasonality of the mesozooplankton, there was a separation of the taxa into distinct groups representing the summer, the winter-spring, and the autumn periods. The temperature was the most important variable that shaped the formation of the distinct seasonal groups of taxa, while chlorophyll-α, dissolved oxygen, and salinity contributed to a lesser extent. Chlorophyll-α concentrations verified the oligotrophic character of the area and seem to be unaffected by inland inputs. The mesozooplankton community showed a spatial consistency, probably as the result of the open sea influence, and seems to be regulated mainly by the properties of the central Levantine pelagic waters and less by terrestrial inputs of inland waters.

Influence of nutrient supply on plankton microbiome biodiversity and distribution in a coastal upwelling region

The ecological and oceanographic processes that drive the response of pelagic ocean microbiomes to environmental changes remain poorly understood, particularly in coastal upwelling ecosystems. Here we show that seasonal and interannual variability in coastal upwelling predicts pelagic ocean microbiome diversity and community structure in the Southern California Current region. Ribosomal RNA gene sequencing, targeting prokaryotic and eukaryotic microbes, from samples collected seasonally during 2014-2020 indicate that nitracline depth is the most robust predictor of spatial microbial community structure and biodiversity in this region. Striking ecological changes occurred due to the transition from a warm anomaly during 2014-2016, characterized by intense stratification, to cooler conditions in 2017-2018, representative of more typical upwelling conditions, with photosynthetic eukaryotes, especially diatoms, changing most strongly. The regional slope of nitracline depth exerts strong control on the relative proportion of highly diverse offshore communities and low biodiversity, but highly productive nearshore communities.

Long: Influence of water masses on the summer structure of the seabird community in the northeastern Chukchi Sea.

We used data collected during a variety of research cruises in the northeastern Chukchi Sea and contributed to the Distributed Biological Observatory to explore the influence of the seasonal change in water masses on the development of the seabird community during the summer. Surveys that included seabird observations and hydrographic sampling were conducted from Alaska’s northwestern coast to ~220 km offshore during 2008–2018. Species composition varied geographically, shifting from a nearshore community that included short-tailed shearwaters, loons, and seaducks to an offshore community dominated by crested auklets. Crested auklets were remarkably consistent in their occupation of Hanna Shoal among years and remained in the area throughout the summer. Short-tailed shearwaters exhibited the greatest seasonal and interannual variation in abundance and distribution of the 35 species recorded. They were concentrated south of 71°N and within 50 km of shore in August and tended to spread throughout the region in September. Surface-feeding species like gulls, fulmars, and phalaropes were 1–2 orders of magnitude less abundant and had wider distributions than birds that feed by diving. Including information about hydrography improved the fit of models of seabird density. Seabirds, especially those that breed in the Bering Sea, generally were more abundant in areas dominated by moderate-salinity Bering Sea Water than nearshore in low-salinity Alaska Coastal Water. The distribution of seabirds across the northeastern Chukchi Sea reflected the heterogeneity of oceanic habitats and prey availability over the shallow shelf. Our results will inform efforts to develop ecosystem models that incorporate oceanographic conditions to predict ongoing consequences of climate change.

Non-native Dreissena associated with increased native benthic community abundance with greater lake depth

Although the typical interaction between non-native invasive species and native species is considered to be negative, in some cases, non-native species may facilitate native species. Zebra and quagga mussels (Dreissena spp.) are aggressive invaders in freshwater systems, and they can alter energy flow by diverting nutrients from pelagic to benthic food-webs. In the last two decades, quagga mussels have largely replaced zebra mussels in shallow regions of the Laurentian Great Lakes and colonized deeper waters previously devoid of all dreissenids. Here, we aim to characterize potential positive effects of dreissenids in relation to depth on the benthic community in lakes Michigan and Huron. For this study, we used benthic survey data collected from Lake Michigan in 2015 and Lake Huron in 2017 and annual U.S. EPA Great Lakes National Program Office Long-term Biology Monitoring Program data for both lakes from 1998 to 2019. Benthic species richness and abundance (excluding dreissenids) in both lakes were almost three-fold higher in the nearshore (<70 m) compared to offshore (>70 m) communities. We found that, even though abundance of benthic invertebrates decreased with increased depth, total benthos density and biomass were higher in the presence than in the absence of quagga mussels in both lakes. Moreover, increased quagga mussel density and biomass with depth offset the lower benthos density and biomass at deeper depths, and samples with dreissenids had high densities of oligochaetes in both nearshore and offshore communities. These patterns are consistent with facilitative effects of quagga mussels on both shallow and deep-water benthic communities.

A microbial perspective on the local influence of Arctic rivers and estuaries on Hudson Bay (Canada)

A clear divide typically exists between freshwater and marine microbial communities, with transitional communities found in estuarine zones. The estuarine communities can derive from inflowing rivers and the sea via tidal mixing and incursions or be comprised of unique brackish species, depending on flow regimes and retention time within an estuary. Only a few studies have been carried out in the Arctic, where moderate salinities associated with the influence of seasonal ice melt could potentially favor marine microbes adapted to lower salinities in fresh-to-saltwater transition zones irrespective of river flows and tidal mixing. To test this idea, we examined early summer microbial communities in 2 western Hudson Bay (Canada) river-to-sea systems: the Churchill and Nelson river systems. Both rivers originate from the same headwaters, suggesting similar catchment conditions, but differ in geomorphology and hydroelectric diversions that induce very different flow and stratification regimes. Using amplicons of the V4 region of the 16S rRNA gene, we identified distinct riverine bacterial communities that were significantly different from the 2 associated estuaries and offshore communities. In the much smaller Churchill Estuary, the microbial community showed a marked influence of freshwater microbial species, along with marine influences. In contrast, in the larger high-flow Nelson River Estuary, riverine bacterioplankton were less evident in the estuary, where the marine signal was much stronger. The marine samples in both systems differed somewhat consistently with the phenology of the phytoplankton bloom in the Bay and tended to harbor distinct attached and free-living bacterial communities. Our results highlight the relevance of river flow and estuarine circulation on selection of bacterial species in estuaries, with ecological implications for food web functionality and biogeochemical cycles in the Anthropocene, where flow regimes would be affected by larger climatic variability.

Studies of fishermen’s economic loss due to oil spills

Offshore oil-drilling activities have a significant potential to generate pollutants which of them is from oil spills. Oil spills in the coastal ecosystem harm the marine ecosystem and human activities. The disrupted environment of the waters by the oil spills causes social-economic losses, specifically impacting the decline of fishery products and the community’s living standard on the coast. The immediate economic effect of the oil spills is, among others, the death of marine organisms due to the oil layers on the water surface, causing economic losses to the fishermen. The decline in the marine environment quality is directly proportional to the decrease in fishermen’s incomes. The purpose of this research is to evaluate the fishermen’s economic losses caused by the oil spills. The research method used is the mixed method which is a combination of quantitative and qualitative methods. The outcome of this research is not only the damage of oil spills to the environment, but it also causes an economic impact on the people around the affected area. The connection between the environmental damage and the community’s income is due to the offshore community’s reliance on natural resources as their source of income. The average of the difference fishermen’s losses after oil spills has reached 76% or Rp. 177,875/trip, which is due to the decrease in the fish caught so that the fishermen could not sell them.

Protist communities along freshwater–marine transition zones in Hudson Bay (Canada)

One of the most striking ecological divides on Earth is between marine and nearby freshwater environments, as relatively few taxa can move between the two. Microbial eukaryotes contribute to biogeochemical and energy cycling in both fresh and marine waters, with little species overlap between the two ecosystems. Arctic and sub-Arctic marine systems are relatively fresh compared to tropical and temperate systems, but details of microbial eukaryote communities along river-to-sea transitions are poorly known. To bridge this knowledge gap, we investigated three river-to-sea transitions (Nelson, Churchill, and Great Whale Rivers) in sub-Arctic Hudson Bay through 18S rRNA amplicon sequencing to identify microbial eukaryotes along the salinity and biogeochemical gradients. Salinity acted as the principal dispersal barrier preventing freshwater microorganisms from colonizing marine coastal waters, with microbial eukaryote communities of the three rivers clustering together. Just offshore, communities clustered by coastal regions associated with nutrient concentrations. Analysis of indicator species revealed that communities in the nitrate-depleted coastal water off the Churchill and Great Whale Rivers were dominated by heterotrophic taxa and small photosynthetic protists. In contrast, the Nelson offshore community was characterized by a high proportion of the diatom Rhizosolenia. A distinct community of heterotrophic protists was identified in the three estuarine transition zones, suggesting specialized estuarine communities. Such specialization was most marked in the Nelson River system that was sampled more intensely and showed estuarine circulation. The autochthonous community was composed of the bacterial grazers Katablepharis, Mataza, and Cryothecomonas, as well as brackish species of the diatoms Skeletonema and Thalassiosira. These findings suggest that flow regulation on the Nelson River that modifies estuarine circulation would affect estuarine community composition and distribution in the transition zone.

Keystone species of coastal ecosystems from the Bay of Biscay

Estuarine and coastal ecosystems play a fundamental role in human activities. Since millions of people depend on the numerous resources they offer (i.e., fisheries, transportation, and recreational activities), these ecosystems are also exposed to a high anthropogenic pressure. In order to better monitor and regulate such pressures, it is critical to improve our understanding of the functioning of these ecosystems. This is especially important for microorganisms, considering, for instance, their important roles in biogeochemical cycles. In this study we investigate estuarine and coastal microbial communities along the coast of the Basque Country using eDNA metabarcoding of bacterioplankton and microbenthos samples along a time series, from locations that present different degrees of disturbance. Metabarcoding of the 16S and 18S rRNA gene was carried out, and the OTU and taxa tables generated were used to reconstruct ecological networks, representing potential biological interactions. These ecological networks were used to identify on one hand the species that play a major role in the maintenance of the whole community structure (keystones), and on the other, complex network modules affected by environmental impacts. Here, we define keystone taxa as those that presented the highest ratio between the degree of connectivity (number of associations they established within the network) and their relative abundance. The underlying aim of this study is to develop novel “bioindicators” based on taxa that are both sensitive to impacts and important for community structure. Results of two seawater communities, one from offshore waters and the other from the coast, showed similar bacterial composition at family level, dominated by Flavobacteraceae and Rhodobacteraceae. Nevertheless, their ecological network properties differed strongly: for a similar number of taxa that established associations, the conectance was similar in both communities, but the number of associations in the coastal community was twice as high as for the offshore one, resulting in a higher modularity. Identified keystone taxa were taxonomically different between both communities: those from the coastal community belonged to Protobacteria, Bacteroidetes, Firmicutes, and Fusobacteria phyla, while the keystones from the offshore community belonged to Proteobacteria, Actinobacteria, Chloroflexi, Thaumarchaeota, PAUC34f and Verrucomicrobia. Moreover, we identified “connector” taxa that presented the highest values of betweenness centrality. These taxa, without having a high degree of connectivity, may be important for the interaction structure because they connect modules, i.e., highly connected subnetworks within the whole network. Further, hierarchical clustering was performed to identify seasonal trends and to better understand the associations retrieved. Taxa with different seasonal preference often grouped together in the same modules, which indicates that modularity was not caused primarily by seasonality.

Biodiversity loss leads to reductions in community‐wide trophic complexity

AbstractWith increasing biodiversity loss occurring worldwide, there is a need to understand how these losses will affect ecosystem structure and function. Biodiversity loss leads to changes in species interactions and alters the trophic complexity of food webs. These alterations to trophic complexity can be described by changes to the diversity of food resources and the diversity of trophic levels. To understand how biodiversity affects trophic complexity of food webs, we used 10 islands across the Aleutian Archipelago to compare the alternate state communities found in kelp forest ecosystems (kelp forest and urchin barren communities) and then compared these to natural reference communities without local benthic production (their associated offshore communities). We constructed food webs for each community across the Aleutian Archipelago using primary producer and consumer carbon (δ13C, a proxy for food sources to a consumer) and nitrogen (δ15N, a proxy for consumer trophic level) stable isotope values. Our findings suggest that biodiversity loss (i.e., phase change from kelp forest to urchin barren) leads to reductions in trophic complexity, which was similar to naturally occurring communities with low local resource biodiversity. This was expressed by lower consumer isotopic dietary niche areas, especially omnivores and herbivores, and lower omnivore and carnivore trophic levels within the urchin barren communities. We clarify how biodiversity promotes food resources and increases trophic levels and complexity through critical trophic conduits.

History of Deer Herd Reduction for Tick Control on Maine’s Offshore Islands

The incidence of Lyme disease in Maine is associated with high abundance of blacklegged (deer) ticks, which in turn has been partly attributed to local overabundance of white-tailed deer. With evidence from Monhegan Island that the complete removal of deer reduced ticks and risk of contracting Lyme disease, nine other offshore communities initiated efforts to cull deer. We reviewed and summarized available histories of deer management on Maine’s offshore islands. Concern about Lyme disease provided the overarching impetus for deer culls. Culls mostly occurred on islands that have no regular firearms hunting season, island communities have been challenged to control deer numbers, and social acceptance of deer culls varied. Integrated tick management (ITM) is the key to controlling ticks, but statewide ITM policy is lacking. Formation of vector control districts with statewide ITM policy would support all communities in Maine.

Discussion: A review on the behaviour of helical piles as a potential offshore foundation system

Helical piles have emerged as an attractive foundation system for offshore applications with renewed interest from the offshore community. Significant research gap currently exists in transferring this technology offshore and this paper discusses how existing and emerging knowledge can be successfully used to bridge some of the gaps. We focus on the Coupled Eulerian Lagrangian (CEL) large deformation finite element (LDFE) modelling technique that is commercially available and can be used to model the three-dimensional installation process with consideration of strain rate and softening effects in soft offshore clays. A helical pile of L = 7.5 m long is modelled with one or two large-diameter helices (D = 2 m) attached to a central shaft of d = 0.5 m in diameter.The net effect of strain rate and softening is to increase the installation torque. The measured torque is within the range of 200–400 kN.m for the offshore clay and the pile geometry studied. Additional helices increase the uplift force but to a lesser degree than that of the measured torque. Remoulding induced strength reduction is found to be within the range of 25–33% of the intact clay strength. Issues of extracting and reusing offshore helical pile foundations are discussed.

Threespine Stickleback of the White Sea: Population Characteristics and Role in the Ecosystem

This review summarizes and analyzes data on the threespine stickleback Gasterosteus aculeatus L. of the White Sea, which is currently the most abundant fish in the region and, therefore, plays an important role in inshore and offshore communities. The threespine stickleback was abundant in the 1920s–1940s; its numbers declined significantly between the late 1960s and late 1990s and have increased again since then, showing a positive correlation with water temperature. In order to reveal the mechanisms of changes in the population of this species and to assess its role in the marine ecosystems, various aspects of the population biology of the species (interannual and seasonal population dynamics, spatial heterogeneity, age and sex structure, lipid and fatty acid status, homing, and fluctuating asymmetry), as well as its interactions with other organisms (feeding characteristics of adults and juveniles, role in feeding predatory fish, association with eelgrass, parasite composition and spatial distribution, and relationships with competing species) are analyzed.

Distributive Justice, Community Benefits and Renewable Energy: The Case of Offshore Wind Projects

Renewable energy projects bring about benefits to society as a whole, yet they affect citizens living in their vicinity. Negative externalities associated with renewable energy projects, such as noise or visual impact, cause local resistance to them. Community benefits bring about an element of distributive justice to these affected citizens and their communities as a form of compensation vis-a-vis these negative effects. This chapter analyzes the role, nature and modalities of community benefits regarding offshore wind projects by using the North Sea as a case study. It shows how different countries adopt diverse approaches in a varied regulatory landscape, and how new technological renewable energy solutions influence the types of benefits granted as well as their scope and extent. It concludes by demonstrating that even if offshore wind farms are located further offshore community benefits are still awarded by project developers and states as elements of energy justice and, recognition of citizens’ rights and expectations.

Power Flow Optimization for an Offshore Multi-energy System

Qu, B.; Zhong, M.; Jia, H.; Yan, H.; Zhang, J., and Sun, Y., 2019. Power flow optimization for an offshore multi-energy system. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 585–596. Coconut Creek (Florida), ISSN 0749-0208.The increase of offshore PV and wind power installation capacity can increase the uncertainty and randomness of the power system. Therefore, it is necessary to study the offshore multi-energy system. A traditional offshore community with hybrid energy storage system (HESS) installation usually participates in demand response program to improve system economy. However, due to the high price and low discharge power of the HESS, it cannot response to the loads effectively. This paper introduces water electrolysis and on-board hydrogen storage technologies to an offshore multi-energy system, so as to effectively optimize the operation of system. Subsequently, to analyze the impact of climate change on system operation, the concept of loads matching degree is firstly defined. Finally, this paper gives a suggestion for an existed offshore multi-energy system on how to reasonably increase renewable generation system installation capacity. Results show that compared with the traditional offshore multi-energy system, the improved system can significantly reduce system operation costs and carbon emissions by 23.02% and 48.43%, respectively. Additionally, with the increase of loads matching degree, offshore system optimal operation costs, carbon emissions and the amount of hydrogen produced by water electrolysis reduce significantly. Finally, the growth of renewable energy generation capacity can lead to the reduce of emissions and increase of operating costs.