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Recently, Gallagher et al. (2022) suggested that seaweed ecosystems are net heterotrophic carbon sources due to CO2 released from the consumption of external subsidies. Here we outline several flaws in their argument, which we believe confuse research on the blue carbon potential of seaweed ecosystems, and unjustifiably generate doubt around initiatives to protect and restore seaweed forests. Gallagher et al.'s evidence relies on 18 studies with highly variable measures of net ecosystem production, which do not statistically support their conclusion that most seaweed ecosystems are heterotrophic. This dataset is also inappropriate as it is incomplete and misrepresents seaweed ecosystems globally, particularly seaweed forests, which contribute disproportionately to global seaweed productivity. We maintain that the climate change mitigation value of an ecosystem depends on the net difference in CO2 uptake between the original ecosystem and its replacement ecosystem. We provide evidence that most seaweed ecosystems, which drawdown the largest carbon flux of any vegetated coastal habitat, are indeed net autotrophic ecosystems. We recognize that substantial uncertainties remain concerning the magnitude of CO2 drawdown by seaweed ecosystems and recommend that carbon fluxes around seaweed ecosystems should be considered more broadly and taken into account in estimates of their CO2 mitigation potential. [ABSTRACT FROM AUTHOR]

Transformative governance is key to addressing the global environmental crisis. We explore how transformative governance of complex biodiversity–climate–society interactions can be achieved, drawing on the first joint report between the Intergovernmental Panel on Climate Change and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services to reflect on the current opportunities, barriers, and challenges for transformative governance. We identify principles for transformative governance under a biodiversity–climate–society nexus frame using four case studies: forest ecosystems, marine ecosystems, urban environments, and the Arctic. The principles are focused on creating conditions to build multifunctional interventions, integration, and innovation across scales; coalitions of support; equitable approaches; and positive social tipping dynamics. We posit that building on such transformative governance principles is not only possible but essential to effectively keep climate change within the desired 1.5 degrees Celsius global mean temperature increase, halt the ongoing accelerated decline of global biodiversity, and promote human well-being. [ABSTRACT FROM AUTHOR]

We have supplemented available, concurrent measurements of fresh weight (W, g) and body carbon (C, g) (46 individuals, 14 species) and nitrogen (N, g) (11 individuals, 9 species) of marine gelatinous animals with data obtained during the global ocean MALASPINA 2010 Expedition (totalling 267 individuals and 33 species for the W versus C data; totalling 232 individuals and 31 species for the N versus C data). We then used those data to test the allometric properties of the W versus C and N versus C relationships. Overall, gelatinous organisms contain 1.13 ± 1.57% of C (by weight, mean ± SD) in their bodies and show a C:N of 4.56 ± 2.46, respectively, although estimations can be improved by using separate conversion coefficients for the carnivores and the filter feeders. Reduced major axis regression indicates that W increases isometrically with C in the carnivores (cnidarians and ctenophores), implying that their water content can be described by a single conversion coefficient of 173.78 gW(g C)-1, or a C content of 1.17 ± 1.90% by weight, although there is much variability due to the existence of carbon-dense species. In contrast, W increases more rapidly than C in the filter feeders (salps and doliolids), according to a power relationship W = 446.68C1.54. This exponent is not significantly different from 1.2, which is consistent with the idea that the watery bodies of gelatinous animals represent an evolutionary response towards increasing food capture surfaces, i.e. a bottom-up rather than a top-down mechanism. Thus, the available evidence negates a bottom-up mechanism in the carnivores, but supports it in the filter feeders. Last, N increases isometrically with C in both carnivores and filter feeders with C:N ratios of 3.89 ± 1.34 and 4.38 ± 1.21, respectively. These values are similar to those of compact, non-gelatinous organisms and reflect a predominantly herbivorous diet in the filter feeders, which is confirmed by a difference of one trophic level between filter feeders and carnivores, according to stable N isotope enrichment data. [ABSTRACT FROM AUTHOR]

The proliferation of a number of pressures affecting the ocean is leading to a growing concern that the state of the ocean is compromised, which is driving society into pessimism. Ocean calamities are disruptive changes to ocean ecosystems that have profound impacts and that are widespread or global in scope. However, scrutiny of ocean calamities to ensure that they can be confidently attributed to human drivers, operate at widespread or global scales, and cause severe disruptions of marine social-ecosystems shows that some of the problems fail to meet these requirements or that the evidence is equivocal. A number of biases internal and external to the scientific community contribute to perpetuating the perception of ocean calamities in the absence of robust evidence. An organized auditing of ocean calamities may deliver a more precise diagnosis of the status of the oceans, which may help to identify the most pressing problems that need be addressed to conserve a healthy ocean. [ABSTRACT FROM AUTHOR]

We estimated the bacterial production and losses to predators along an open ocean trophic gradient from coastal upwelling waters to oligotrophic waters in the Subtropical Northern Atlantic Ocean. Two zonal sections (21 and 26°N) extending from the NW African shelf to the Open Atlantic Ocean at 26°W were sampled during September–October 2002 (autumn), and May–June 2003 (spring). The main goal was to elucidate whether the impacts of bacterial losses were more important in upwelling rather than in offshore waters. Whereas temperature and salinity decreased and nutrient concentrations increased from offshore to the coastal upwelling regions, phytoplankton, ciliate and bacterial biomass followed a similar trend increasing towards the upwelling zone. In addition, heterotrophic nanoflagellate biomass, bacterial production and grazing rates on bacteria did not follow this pattern, although the highest activities were recorded at upwelling stations. However, at the stations not affected by upwelling the average impact on bacteria expressed as a percentage of bacterial production consumed by predators in autumn and spring (values that varied between 70% ± 6% and 129% ± 15%, respectively) was significantly higher than at the upwelling stations (where it ranged between 49% ± 7% and 68% ± 5%, respectively). Our results suggest that in the upwelling areas bacteria escape from predators and growth cannot be balanced by grazing, while it is at the oligotrophic open ocean stations when, on occasions, grazing can overcome bacterial production. [ABSTRACT FROM PUBLISHER]

Nitrogen fixation by the diazotrophic community in the subtropical NE Atlantic, including the Canary Current region, was investigated during two oceanographic cruises, RODA I (summer 2006) and RODA II (winter 2007). The first evaluated the role of the Canary eddy fields in the growth of nitrogen-fixing Trichodesmium and their rates of nitrogen fixation and of the unscreened whole diazotrophic community. The second cruise was designed to look at the variability of these processes in the subtropical NE Atlantic study area that is influenced by atmospheric transport of African aerosols. During RODA I, significantly higher mean nitrogen fixation rates of unscreened whole surface water (P < 0.05, t-test) were observed at oligotrophic far-field stations than in the nutrient-enriched eddies, but the pattern was not consistent with nitrogen fixation rates of >50 µm samples (Trichodesmium) integrated over depth. However, correlation analyses showed decreasing rates of nitrogen fixation rates of >50 µm samples (Trichodesmium) at stations with higher NH4+ concentrations, suggesting that combined N seemed to be an important regulator affecting nitrogen fixation rates. Temperature was also correlated with the abundance of Trichodesmium. Iron (from dust deposition), which has been reported in previous studies to stimulate N2 fixation, did not show any correlation with N2 fixation rates or with the abundance of Trichodesmium. [ABSTRACT FROM PUBLISHER]

During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historical context to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference for changes in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms. [ABSTRACT FROM AUTHOR]

Defining biogeographic provinces to understand the history and evolution of communities associated with a given kind of ecosystem is challenging and usually requires a priori assumptions to be made. We applied network theory, a holistic and exploratory method, to the most complete database of faunal distribution available on oceanic hydrothermal vents, environments which support fragmented and unstable ecosystems, to infer the processes driving their worldwide biogeography. Besides the identification of robust provinces, the network topology allowed us to identify preferential pathways that had hitherto been overlooked. These pathways are consistent with the previously proposed hypothesis of a role of plate tectonics in the biogeographical history of hydrothermal vent communities. A possible ancestral position of the Western Pacific is also suggested for the first time. Finally, this work provides an innovative example of the potential of network tools to unravel the biogeographic history of faunal assemblages and to supply comprehensive information for the conservation and management of biodiversity. [ABSTRACT FROM PUBLISHER]

Constraints on the availability of freshwater and land plants and animals to feed the 9.2 billion humans projected to inhabit Earth by 2050 can be overcome by enhancing the contribution the ocean makes to food production. Catches from ocean fisheries are unlikely to recover without adequate conservation measures, so the greater contribution of the oceans to feeding humanity must be derived largely from mariculture. For the effort to be successful, mariculture must close the production cycle to abandon its current dependence on fisheries catches; enhance the production of edible macroalgae and filter-feeder organisms; minimize environmental impacts; and increase integration with food production on land, transferring water-intensive components of the human diet (i.e., production of animal protein) to the ocean. Accommodating these changes will enable the oceans to become a major source of food, which we believe will constitute the next food revolution in human history. [ABSTRACT FROM AUTHOR]

Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions. They also serve as "coastal canaries," global biological sentinels of increasing anthropogenic influences in coastal ecosystems, with large-scale losses reported worldwide. Multiple stressors, including sediment and nutrient runoff, physical disturbance, invasive species, disease, commercial fishing practices, aquaculture, overgrazing, algal blooms, and global warming, cause seagrass declines at scales of square meters to hundreds of square kilometers. Reported seagrass losses have led to increased awareness of the need for seagrass protection, monitoring, management, and restoration, However, seagrass science, which has rapidly grown, is disconnected from public awareness of seagrasses, which has lagged behind awareness of other coastal ecosystems. There is a critical need for a targeted global conservation effort that includes a reduction of watershed nutrient and sediment inputs to seagrass habitats and a targeted educational program informing regulators and the public of the value of seagrass meadows. [ABSTRACT FROM AUTHOR]

The trophic relation between prokaryotes and heterotrophic nanoflagellates was studied during two latitudinal cruises in the central Atlantic Ocean. The losses to predation on prokaryotes were determined in 12 locations covering a wide range of trophic situations, from ultraoligotrophic [<0.05 mg chlorophyll a (Chl a) m–3] to moderately eutrophic waters (>1 mg Chl a m–3). In these locations, the abundance of prokaryotes (P) covaries with that of heterotrophic nanoflagellates, thus suggesting that resources controlled the abundance of heterotrophic nanoflagellates (HNF). Besides, the losses to predation were positively related to prokaryotic and heterotrophic nanoflagellate biomass, which points toward higher consumption rates associated with larger concentrations of preys and predators. Conversely, declining trends between prokaryotic production (PP) and the fraction of this production lost to predation revealed higher relative losses in the environments with lower productions. Our study shows for the central Atlantic that 35% of prokaryotic biomass (BP), equating to between 40 and 83% of PP can be ingested daily and that 55% of the variability observed in the rate of prokaryotic loss to predation was related with the HNF. As predators graze on many prey types, in an oligotrophic system containing many prey species but little numeric loading, there will still be prey for predators but not enough hosts for viruses. In this sense, our study confirms the importance of the prey–predator relationship between prokaryotes and heterotrophic nanoflagellates in the flow of carbon of the less productive regions of the ocean. [ABSTRACT FROM AUTHOR]

Zooplankton abundance, biomass (biovolume) and taxonomic composition were studied within an annual cycle (August 1995–October 1996) in the Bay of Blanes (northwest Mediterranean). Weekly zooplankton sampling included oblique tows made with a 200 μm Juday–Bogorov net, and vertical tows made with a 53 μm net, to adequately sample both mesoplankton and the smaller zooplankton fractions. Total zooplankton abundance showed high variability, lacking any clear seasonal pattern. However, the different species within the zooplankton community displayed a clear succession throughout the year. In general, cyclopoid copepods (Oithona spp.) and cladocerans (Peniliaavirostris) dominated the summer and autumn communities, whereas in winter and spring, calanoid copepods (Clausocalanus spp., Paracalanus sp. and Centropages typicus) were predominant. The zooplankton annual cycle in the Bay of Blanes does not resemble those of other Mediterraneanlittoral areas, probably due to the inherent particularity and variability associated with open coastal environments. On average, the abundance of organisms estimated with a traditional 200 μm Juday–Bogorov net was 8.1 times lower than the values obtained with a 53 μm net. Even if only organisms >200 μm collected in the 53 μm tows were considered, the total abundance within the 53 μm net was still 4.4 times higher than the estimates from the Juday–Bogorov net. These results suggest the need for accurate samplings of the entire zooplankton assemblage when characterizing the structure and dynamics of zooplanktonic communities. [ABSTRACT FROM PUBLISHER]

In this article, the author focuses on the boundaries between scientific evidence and belief in the researches for marine extinctions. Topics discussed include contribution to ocean protection through rigorous analysis of ocean calamities; ignorance of scholarship showing evidence for calamities by researcher Jennifer Jacquet, and eutrophication and hypoxia failing in providing evidence.

The recurrent lack of isolation by distance reported at regional scale in seagrass species was recently suggested to stem from stochastic events of large-scale dispersal. We explored the usefulness of phylogenetic information contained in microsatellite loci to test this hypothesis by using the Genetic Diversity Spectrum (GDS) on databases containing, respectively, 7 and 9 microsatellites genotypes for 1541 sampling units of Posidonia oceanica and 1647 of Cymodocea nodosa. The simultaneous increase of microsatellite and geographic distances that emerges reveals a coherent pattern of isolation by distance in contrast to the chaotic pattern previously described using allele frequencies, in particular, for the long-lived P. oceanica. These results suggest that the lack of isolation by distance, rather than the resulting from rare events of large-scale dispersal, reflects at least for some species a stronger influence of mutation over migration at the scale of the distribution range. The global distribution of genetic polymorphism may, therefore, result predominantly from ancient events of step-by-step (re)colonization followed by local recruitment and clonal growth, rather than contemporary gene flow. The analysis of GDS appears useful to unravel the evolutionary forces influencing the dynamics and evolution at distinct temporal and spatial scales by accounting for phylogenetic information borne by microsatellites, under an appropriate mutation model. This finding adds nuance to the generalization of the influence of large-scale dispersal on the dynamics of seagrasses. [ABSTRACT FROM PUBLISHER]

The gray mangrove [Avicennia marina (Forsk.) Vierh.] is the most widely distributed mangrove species, ranging throughout the Indo-West Pacific. It presents remarkable levels of geographic variation both in phenotypic traits and habitat, often occupying extreme environments at the edges of its distribution. However, subspecific evolutionary relationships and adaptive mechanisms remain understudied, especially across populations of the West Indian Ocean. High-quality genomic resources accounting for such variability are also sparse. Here we report the first chromosome-level assembly of the genome of A. marina. We used a previously release draft assembly and proximity ligation libraries Chicago and Dovetail HiC for scaffolding, producing a 456,526,188-bp long genome. The largest 32 scaffolds (22.4–10.5 Mb) accounted for 98% of the genome assembly, with the remaining 2% distributed among much shorter 3,759 scaffolds (62.4–1 kb). We annotated 45,032 protein-coding genes using tissue-specific RNA-seq data in combination with de novo gene prediction, from which 34,442 were associated to GO terms. Genome assembly and annotated set of genes yield a 96.7% and 95.1% completeness score, respectively, when compared with the eudicots BUSCO dataset. Furthermore, an FST survey based on resequencing data successfully identified a set of candidate genes potentially involved in local adaptation and revealed patterns of adaptive variability correlating with a temperature gradient in Arabian mangrove populations. Our A. marina genomic assembly provides a highly valuable resource for genome evolution analysis, as well as for identifying functional genes involved in adaptive processes and speciation. [ABSTRACT FROM AUTHOR]