Publications

Variable response of Red Sea coral communities to recent disturbance events along a latitudinal gradient

Seaweed forests are carbon sinks that can mitigate CO2 emissions

The paper — Seaweed ecosystems may not mitigate CO2 emissions (Gallagher et al., 2022) — claims that seaweed ecosystems are carbon sources rather than carbon sinks because ‘respiration subsidies’ (from inputs of allochthonous organic carbon) create negative net ecosystem production. That is, that seaweed ecosystems produce more CO2 than they draw down, and thus may not mitigate CO2 emissions. They make this claim using a compiled dataset which shows that, on average, seaweed ecosystems are net heterotrophic. However, their assessment is flawed and conceptually misleading as key terms are misinterpreted, the data presented are biased, and the conclusions are not supported statistically. Here we discuss four flaws in the argument presented by Gallagher et al., which we believe risk confusing further research on seaweed blue carbon and unjustifiably seeding doubt around motivations and initiatives to protect and restore seaweed forests.

Temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean

Abstract. The temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperature gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, the highest rates being observed during the spring transect. The overall mean integrated GPP / CR ratio was 1.39 ± 0.27 decreasing from winter to summer, and the NCP for the subtropical North Atlantic Ocean during the cruises exhibits net autotrophy (NCP > 0) in about two-thirds (66%) of the total sampled communities. Also, we reported the activation energies describing the temperature dependence of planktonic community metabolism, which was generally higher for CR than for GPP in the subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Furthermore, we made a comparison of activation energies describing the responses to in situ temperature in the field (EaCR = 1.64 ± 0.36 eV) and those derived experimentally by temperature manipulations (EaCR = 1.45 ± 0.6 eV), which showed great consistency.

Carbon and nutrient fluxes across tropical river-coastal boundaries

Diversity and Sources of Airborne Eukaryotic Communities (AEC) in the Global Dust Belt over the Red Sea

Abstract Airborne eukaryotic communities (AEC), rank among the least studied aerobiological components, despite their adverse impacts on human health and the environment. Here, we describe the AECs in the global dust belt, the area between the west coast of North Africa and Central Asia, which supports the highest dust fluxes on the planet. We sampled atmospheric dust over 14 months (fall 2015–fall 2016) from onshore and offshore locations of the Red Sea, the only waterbody that entirely encompassed in the global dust belt. We also sampled surface water samples to determine the potential transfer of taxa across the air-sea interface. To target the eukaryotes, we performed Miseq sequencing of atmospheric dust and surface water samples. Analysis of amplicon sequencing indicates a total pool of 18,816 sequence variants (SVs). Among 33 unique eukaryotic phyla in the AEC over the Red Sea, the most dominant taxa were Streptophyta, Apicomplexa, and Ascomycota. Aerosol eukaryotes originated from various sources and formed more diverse communities than eukaryotic communities of the Red Sea surface water. AECs were dominated by phylotypes released from plant material and soils, and including taxa reported to be harmful to human health. The AEC composition was significantly influenced by sampling locations and seasonal conditions but not by the origin of the air masses nor dust loads. This work is original and uses state-of-the-art methods and very powerful NGS- bioinformatics and statistical approaches. The selected study site has high interest and it has been well chosen because of the unique combination of high loads of dust deposition, being the only fully contained seawater body in the area acting as a sink for the atmospheric dust, and the lack of riverine inputs and watershed effects empathizing the role of atmospheric inputs in the ecology of the system.

Isotopic footprints (15N/14N, 13C/12C) in the marine biomass: the base of the trophic chain.

Population age structure and rhizome growth of Cymodocea nodosa in the Ria Formosa (southern Portugal)

Towards a unifying pan-arctic perspective: A conceptual modelling toolkit

Diterpenes featuring the spatane, seco-spatane and prenylcubebane carbocycles from the invasive brown alga Rugulopteryx okamurae

Seagrass colonization: patch formation and patch growth in Cymodocea nodosa

Thls study demonstrates that patch development in a Mediterranean con~munity of Cymodocea nodosa (Ucria) Ascherson, growing over highly mobile sandy sediments, proceeds by colonization by seedlings (0.047 m-' yr-'), and subsequent patch development by the surviving seedlings (< 10 %).Increased patch cover is obtalned by fast growlng rhizomes (average elongat~on = 1.6 m yr-'), and coalescence of neighbour patches.Honzontal patch growth varied substantially among patches due to enhanced patch elongat~on with Increasing patch slze, whereas growth vanance withln patches was attributable to interannual d~fferences consistent among d~fferent patches.Comparisons of the measured patch spread rates with those for other seagrasses specles show substantial variability (> 2 orders of m a g n ~t u d e ) in horizontal growth rates that ~m p l ~e s broad d~fferences in the potent~al for recovery among seagrass species

Rapid accretion of dissolved organic carbon in the Springs of Florida: the most organic-poor natural waters

Abstract. The concentration of dissolved organic carbon (DOC) in groundwater emanating as spring discharge at several locations in Florida, USA, and the net rate of DOC increase in the downstream receiving waters were measured as part of a larger investigation of carbon dynamics in flowing waters. Springs with high discharge (&gt;2.8 m3 s−1) were found to be the most organic-poor natural waters yet reported (13 ±1.6 μmol C L−1), while springs with lesser discharge exhibited somewhat higher DOC concentrations (values ranging from 30 to 77 μmol C L−1). DOC concentrations increased rapidly downstream from the point of spring discharge, with the calculated net areal input rate of DOC ranging from 0.04 to 1.64 mol C m−2 d−1 across springs. Rates of DOC increase were generally greater in those springs with high discharge rates. These input rates compare favorably with values reported for gross primary production in these macrophyte-dominated spring systems, assuming that 17% of macrophyte primary production is lost, on average, as DOC. The measures reported here are possible only because of the remarkably low DOC levels in the up-surging groundwaters and the short residency times of the water in the spring-runs themselves.

Seawater carbonate chemistry and oxygen concentrations in the Greenland tidal pools

UN Decade on Ecosystem Restoration 2021–2030—What Chance for Success in Restoring Coastal Ecosystems?

OPINION article Front. Mar. Sci., 20 February 2020Sec. Marine Ecosystem Ecology Volume 7 - 2020 | https://doi.org/10.3389/fmars.2020.00071

Synergistic effects of hypoxia and increasing CO2 on benthic invertebrates of the central Chilean coast

Ocean acidification and hypoxic events are an increasing worldwide problem, but the synergetic effects of these factors are seldom explored. However, this synergetic occurrence of stressors is prevalent. The coastline of Chile not only suffers from coastal hypoxia but the cold, oxygen-poor waters in upwelling events are also supersaturated in CO2, a study site to explore the combined effect of ocean acidification and hypoxia. We experimentally evaluated the metabolic response of different invertebrate species (2 anthozoans, 9 molluscs, 4 crustaceans, 2 echinoderms) of the coastline of central Chile (33°30’S, 71°37’W) to hypoxia and ocean acidification within predicted levels and in a full factorial design. Organisms were exposed to 4 different treatments (ambient, low oxygen, high CO2, and the combination of low oxygen and high CO2) and metabolism was measured after 3 and 6 days. We show that the combination of hypoxia and increased pCO2 reduces the respiration significantly, compared to a single stressor. The evaluation of synergistic pressures, a more realistic scenario than single stressors, is crucial to evaluate the effect of future changes for coastal species and our results provide the first insight on what might happen in the next 100 years.

A sea of ice

Fully-Automated Fluorimetric Determination of Aluminum in Seawater by In-Syringe Dispersive Liquid–Liquid Microextraction Using Lumogallion

A sensitive and selective automated in-syringe dispersive liquid-liquid microextraction (DLLME) method is presented. It was successfully applied to the determination of aluminum in coastal seawater samples. The complete analytical procedure including sampling, buffering, reaction of the analyte with fluorescence reagent lumogallion (LMG), extraction, phase separation, and quantification was completely automized and carried out within 4 min. DLLME was done using n-hexanol as an extracting solvent and ethanol as a dispersing solvent in a 1:8 v/v percent mixture. The Al-LMG complex was extracted by an organic solvent and separated from the aqueous phase within the syringe of an automated syringe pump. Two devices were specially developed for this work. These were (a) the fluorescence detector and accompanying flow cell for the organic phase enriched with the reaction product and (b) a heating device integrated into the holding coil to accelerate the slow reaction kinetics. The limits of detection (3σ) and quantification (10σ) were 8.0 ± 0.5 nmol L(-1) and 26.7 ± 1.6 nmol L(-1), respectively. The relative standard deviation for eight replicate determinations of 200 nmol L(-1) Al(3+) was <1.5%. The calibration graph using the preconcentration system was linear up to 1000 nmol L(-1) with a correlation coefficient of 0.999. Ambient concentrations of samples were quantifiable with found concentrations ranging from 43 to 142 nmol L(-1). Standard additions gave analyte recoveries from 97% to 113% proving the general applicability and adequateness of the analyzer system to real sample analysis.

Erratum: Oxygen dynamics in the rhizosphere of Cymodocea rotundata (Marine Ecology Progress Series (1998) 169 (283-288))

Resilience of Small Islands: Unveiling Nature-Based Solutions for Sustainable Futures