The true costs of knowledge exchange – a checklist

Planning and budgeting knowledge exchange activities can often be a black box exercise, with activity occurring in an ad-hoc and un-costed fashion. Drawing on case studies of successful knowledge exchange projects, Denis Karcher and Chris Cvitanovic present a framework for where costs fall in knowledge exchange processes and a checklist for researchers looking to plan for knowledge exchange

Nitrogen eutrophication particularly promotes turf algae in coral reefs of the central Red Sea

While various sources increasingly release nutrients to the Red Sea, knowledge about their effects on benthic coral reef communities is scarce. Here, we provide the first comparative assessment of the response of all major benthic groups (hard and soft corals, turf algae and reef sands-together accounting for 80% of the benthic reef community) to in-situ eutrophication in a central Red Sea coral reef. For 8 weeks, dissolved inorganic nitrogen (DIN) concentrations were experimentally increased 3-fold above environmental background concentrations around natural benthic reef communities using a slow release fertilizer with 15% total nitrogen (N) content. We investigated which major functional groups took up the available N, and how this changed organic carbon (C-org) and N contents using elemental and stable isotope measurements. Findings revealed that hard corals (in their tissue), soft corals and turf algae incorporated fertilizer N as indicated by significant increases in delta N-15 by 8%, 27% and 28%, respectively. Among the investigated groups, C-org content significantly increased in sediments (+24%) and in turf algae (+33%). Altogether, this suggests that among the benthic organisms only turf algae were limited by N availability and thus benefited most from N addition. Thereby, based on higher C-org content, turf algae potentially gained competitive advantage over, for example, hard corals. Local management should, thus, particularly address DIN eutrophication by coastal development and consider the role of turf algae as potential bioindicator for eutrophication.Peer reviewe

Nitrogen fixation and denitrification activity differ between coral- and algae-dominated Red Sea reefs

Coral reefs experience phase shifts from coral- to algae-dominated benthic communities, which could affect the interplay between processes introducing and removing bioavailable nitrogen. However, the magnitude of such processes, i.e., dinitrogen (N-2) fixation and denitrification levels, and their responses to phase shifts remain unknown in coral reefs. We assessed both processes for the dominant species of six benthic categories (hard corals, soft corals, turf algae, coral rubble, biogenic rock, and reef sands) accounting for>98% of the benthic cover of a central Red Sea coral reef. Rates were extrapolated to the relative benthic cover of the studied organisms in co-occurring coral- and algae-dominated areas of the same reef. In general, benthic categories with high N-2 fixation exhibited low denitrification activity. Extrapolated to the respective reef area, turf algae and coral rubble accounted for>90% of overall N-2 fixation, whereas corals contributed to more than half of reef denitrification. Total N-2 fixation was twice as high in algae- compared to coral-dominated areas, whereas denitrification levels were similar. We conclude that algae-dominated reefs promote new nitrogen input through enhanced N-2 fixation and comparatively low denitrification. The subsequent increased nitrogen availability could support net productivity, resulting in a positive feedback loop that increases the competitive advantage of algae over corals in reefs that experienced a phase shift.Peer reviewe

High rates of carbon and dinitrogen fixation suggest a critical role of benthic pioneer communities in the energy and nutrient dynamics of coral reefs

Following coral mortality in tropical reefs, pioneer communities dominated by filamentous and crustose algae efficiently colonize substrates previously occupied by coral tissue. This phenomenon is particularly common after mass coral mortality following prolonged bleaching events associated with marine heatwaves. Pioneer communities play an important role for the biological succession and reorganization of reefs after disturbance. However, their significance for critical ecosystem functions previously mediated by corals, such as the efficient cycling of carbon (C) and nitrogen (N) within the reef, remains uncertain. We used 96 carbonate tiles to simulate the occurrence of bare substrates after disturbance in a coral reef of the central Red Sea. We measured rates of C and dinitrogen (N-2) fixation of pioneer communities on these tiles monthly over an entire year. Coupled with elemental and stable isotope analyses, these measurements provide insights into macronutrient acquisition, export and the influence of seasonality. Pioneer communities exhibited high rates of C and N(2)fixation within 4-8 weeks after the introduction of experimental bare substrates. Ranging from 13 to 25 mu mol C cm(-2) day(-1)and 8 to 54 nmol N cm(-2) day(-1), respectively, C and N(2)fixation rates were comparable to reported values for established Red Sea coral reefs. This similarity indicates that pioneer communities may quickly compensate for the loss of benthic productivity by corals. Notably, between 40% and 85% of fixed organic C was exported into the environment, constituting a vital source of energy for the coral reef food web. Our findings suggest that benthic pioneer communities may play a crucial, yet overlooked role in the C and N dynamics of oligotrophic coral reefs by contributing to the input of new C and N after coral mortality. While not substituting other critical ecosystem functions provided by corals (e.g. structural habitat complexity and coastal protection), pioneer communities likely contribute to maintaining coral reef nutrient cycling through the accumulation of biomass and import of macronutrients following coral loss. A freePlain Language Summarycan be found within the Supporting Information of this article.Peer reviewe

Nutrient pollution enhances productivity and framework dissolution in algae- but not in coral-dominated reef communities

Ecosystem services provided by coral reefs may be susceptible to the combined effects of benthic species shifts and anthropogenic nutrient pollution, but related field studies are scarce. We thus investigated in situ how dissolved inorganic nutrient enrichment, maintained for two months, affected community-wide biogeochemical functions of intact coral- and degraded algae-dominated reef patches in the central Red Sea. Results from benthic chamber incubations revealed 87% increased gross productivity and a shift from net calcification to dissolution in algae-dominated communities after nutrient enrichment, but the same processes were unaffected by nutrients in neighboring coral communities. Both community types changed from net dissolved organic nitrogen sinks to sources, but the increase in net release was 56% higher in algae-dominated communities. Nutrient pollution may, thus, amplify the effects of community shifts on key ecosystem services of coral reefs, possibly leading to a loss of structurally complex habitats with carbonate dissolution and altered nutrient recycling.Peer reviewe

Nutrient pollution enhances productivity and framework dissolution in algae- but not in coral-dominated reef communities

Ecosystem services provided by coral reefs may be susceptible to the combined effects of benthic species shifts and anthropogenic nutrient pollution, but related field studies are scarce. We thus investigated in situ how dissolved inorganic nutrient enrichment, maintained for two months, affected community-wide biogeochemical functions of intact coral- and degraded algae-dominated reef patches in the central Red Sea. Results from benthic chamber incubations revealed 87% increased gross productivity and a shift from net calcification to dissolution in algae-dominated communities after nutrient enrichment, but the same processes were unaffected by nutrients in neighboring coral communities. Both community types changed from net dissolved organic nitrogen sinks to sources, but the increase in net release was 56% higher in algae-dominated communities. Nutrient pollution may, thus, amplify the effects of community shifts on key ecosystem services of coral reefs, possibly leading to a loss of structurally complex habitats with carbonate dissolution and altered nutrient recycling.This work was supported by KAUST baseline funding to BHJ and by grant Wi 2677/9-1 from the German Research Foundation (DFG) to C

A systematic literature review of climate change research on Europe's threatened commercial fish species

Climate change poses a major challenge for global marine ecosystems and species, leading to a wide range of biological and social-ecological impacts. Fisheries are among the well-known sectors influenced by multiple effects of climate change, with associated impacts highly variable among species and regions. To successfully manage fisheries, scientific evidence about the potential direct and indirect impacts of climate change on the species targeted by fisheries is needed to inform decision-making processes. This is particularly pertinent for fisheries within European seas, as they include some of the fastest warming water bodies globally, and are thus experiencing some of the greatest impacts. Here, we systematically examine the existing scientific climate-related literature of 68 species that are both commercially important in European seas and considered threatened ac-cording to the IUCN Red List to understand the extent of information that is available to inform fisheries management and identify critical knowledge gaps that can help to direct future research effort. We also explore the climate and fishing vulnerability indices of species as potential drivers of current scientific attention. We found no literature for most of these species (n = 45), and for many others (n = 19) we found fewer than five papers studying them. Climate change related research was dominated by a few species (i.e., Atlantic salmon, European pilchard, and Atlantic bluefin tuna) and regions, such as the Northeast Atlantic, revealing a highly uneven distribution of research efforts across European seas. Most studies were biologically focused and included how abundance, distribution, and physiology may be affected by warming. Few studies incorporated some level of social-ecological information. Moreover, it appears that research on species with high climate and fishing vulnerabilities is not currently prioritized. These results highlight a gap in our understanding of how climate change can impact already threatened species and the people who depend on them for food and income. Our findings also suggest that future climate-specific adaptation measures will likely suffer from a lack of robust information. More research is needed to include all the species from our list, their relevant geographic regions, and subsequent biological and social-ecological implications.La Caixa Foundation LCF/BQ/DI21/11860039, LA/P/0101/2020, ID 100010434info:eu-repo/semantics/publishedVersio

High plasticity of nitrogen fixation and denitrification of common coral reef substrates in response to nitrate availability

Nitrogen cycling in coral reefs may be affected by nutrient availability, but knowledge about concentrationdependent thresholds that modulate dinitrogen fixation and denitrification is missing. We determined the effects of different nitrate concentrations (ambient, 1, 5, 10 mu M nitrate addition) on both processes under two light scenarios (i.e., light and dark) using a combined acetylene assay for two common benthic reef substrates, i.e., turf algae and coral rubble. For both substrates, dinitrogen fixation rates peaked at 5 mu M nitrate addition in light, whereas denitrification was highest at 10 mu M nitrate addition in the dark. At 10 mu m nitrate addition in the dark, a near-complete collapse of dinitrogen fixation concurrent with a 76-fold increase in denitrification observed for coral rubble, suggesting potential threshold responses linked to the nutritional state of the community. We conclude that dynamic nitrogen cycling activity may help stabilise nitrogen availability in microbial communities associated with coral reef substrates.Peer reviewe

Trends in South Pacific fisheries management

International audienceWhile categorized as Small Island Developing States, South Pacific Island nations are the custodians of major ocean areas containing marine resources of high commercial and environmental significance. Yet, these resources are threatened by climate change, overfishing, Illegal, Unreported and Unregulated (IUU) fishing, as well as habitat destruction. The study, carried out in the early stage of the interdisciplinary research project SOCPacific (https://socpacific.net), aims to: a) identify the main policies on which fisheries management is currently based in the South Pacific, particularly in Fiji, New Caledonia and Vanuatu; b) investigate the evolution over time of key issues covered in these policies and related to coastal and/or offshore fisheries sectors; c) trace disconnections on the matter between legally binding instruments and non-binding strategies. A list of more than 200 documents relevant to regional fisheries management was gathered and separated into legally binding instruments and non-binding strategies. Legal instruments focused more on offshore issues (tuna fisheries and IUU fishing) and increasingly covered IUU fishing issues, confirming that tuna fisheries have an established hard policy arena. In strategies pertaining to coastal fisheries, community involvement appears as a key topic and a clear overall trend towards increasingly addressing climate change was spotlighted. Sustainability, community involvement, climate change, and food security issues are more covered in strategies than in legal instruments. Topics mostly addressed in relation to coastal areas are not substantially covered in legal instruments, suggesting that establishing binding measures might not be deemed as beneficial as strategies in coastal fields