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Vast amounts of methane (CH 4) stored in submarine sediments are susceptible to release in a warming Arctic, further exacerbating climate change in a positive feedback. It is therefore critical to monitor CH 4 over pan-regional scales to detect early signs of CH 4 release. However, our ability to monitor CH 4 is hampered in remote northern regions by sampling and logistical constraints, and few good baseline data exist in many areas. From high-resolution atmospheric CH 4 measurements and discrete surface water samples, we estimated instantaneous sea–air CH 4 fluxes at various locations. We also created a baseline study of current background levels of CH 4 in North Atlantic waters based on the atmospheric CH 4 data over 22 d in summer 2021 on a roughly 5100 km voyage in the northern Labrador Sea and Baffin Bay between 55 and 72 ∘ N. In addition, we measured CH 4 concentrations across the water column at various stations. Measured atmospheric mixing ratios of CH 4 ranged from 1944 to 2012 ppbv, with a mean of 1966 ± 8 ppbv and a baseline of 1954–1981 ppbv. Dissolved CH 4 concentrations in the near-surface water peaked at 5.3 nmol L -1 within 1 km down-current of a known cold seep at Scott Inlet and were consistently oversaturated throughout the water column in Southwind Fjord, which is an area that has been recently affected by submarine landslides. Local sea–air CH 4 fluxes ranged from 0.003–0.119 µ mol m -2 d -1 , indicating that the ocean released only small amounts of CH 4 to the atmosphere at all stations. Atmospheric CH 4 levels were also driven by meteorological, spatial, and temporal variations, and both onshore and ocean-based contributions to atmospheric CH 4 mixing ratios are likely. Coupled high-resolution measurements of marine and atmospheric CH 4 data have the potential to provide ongoing monitoring in a region susceptible to CH 4 releases, as well as critical validation data for global-scale measurements and modelling. [ABSTRACT FROM AUTHOR]

Vast amounts of methane (CH4) stored in permafrost and submarine sediments are susceptible to release in warming Arctic, further exacerbating climate change in a positive feedback. It is therefore critical to monitor CH4 over panregional scales to detect early signs of CH4 release. However, our ability to monitor CH4 is hampered in remote northern regions by sampling and logistical constraints and few good baseline data exist in many areas. To create a baseline study of current background levels of CH4 in North Atlantic waters, we collected continuous real-time atmospheric CH4 data, along with ambient air temperature and wind parameters over 22 days in summer 2021 on a roughly 5100 km voyage in the northern Labrador Sea and Baffin Bay up to 71°N. In addition, we measured CH4 concentrations in the water column using discrete water samples at selected stations. Measured atmospheric mixing ratios of CH4 ranged from 1944.7 ppb to 2012.0 ppb, with mean of 1966.0±7.4 ppb and a baseline of 1954.2-1980.6 ppb. Dissolved CH4 concentrations in the near-surface water peaked at 56.58±0.05 nM within 1 km down-current of a known cold seep at Scott Inlet but were consistently super-saturated throughout the water column in Southwind Fjord, which is an area recently affected by submarine landslides. Local sea-air CH4 fluxes ranged from 0.1-14.1 µmol m-2 d-1 indicating that the ocean acted as a CH4 source to the atmosphere. Atmospheric CH4 levels were also driven by meteorological, spatial, and temporal variations. Highest atmospheric CH4 mixing ratios were detected in the Cumberland Sound in Nunavut, suggesting onshore sources from nearby waterbodies and wetlands, whereas ocean-based contributions at this location could not be ruled out. Coupled real-time measurements of marine and atmospheric CH4 data have the potential to provide ongoing monitoring in a region susceptible to CH4 releases, as well as critical validation data for global-scale measurements and modelling. [ABSTRACT FROM AUTHOR]

Using bomb[sup.14]C dating and growth ring counting methods, we Calculate life spans and growth rates of six species of deep-sea corals collected at depths of between 400 and 900 m from the continental slope of Newfoundland and Labrador. Bamboo corals (Acanella arbuscula, Keratoisis ornata) and antipatharians (Stauropathes arctica) secrete concentric growth rings in their axial skeletons, which were proven to form annually for K. ornata and S. arctica. These species had the lowest radial growth rates of 33 [+ or -] 11 to 75 [+ or -] 11[micro]m x [year.sup-1]. Primnoa resedaeformis and Paramuricea spp. had higher radial growth rates of 83 [+ or -] 6 to 215 [+ or -] 37 [micro]m x [year.sup.-1]. Paragorgia arborea had the highest radial growth rate of 830 [+ or -] 120 [micro]m x [year.sup.-1]. Axial growth rates ranged from 0.56 [+ or -] 0.05 cm x [year.sup.-1] for a specimen of Paramuricea spp. to 2.61 [+ or -] 0.45 cm x [year.sup.-1] for a specimen of Primnoa resedaeformis. Life spans ranged from 18 [+ or -] 4 years for a live-collected P. resedaeformis to 200 [+ or -] 30 years for a subfossil specimen of K. ornata. Because all of the corals were from heavily fished areas, it is likely that age distributions are biased towards smaller and younger colonies. Recovery of deep-sea corals from fishing-induced damage will take decades to centuries. L'utilisation de methodes de datation basees sur le [14.sup]C des essais nucleaires et le denombrement des anneaux de croissance nous a permis de determiner la duree de vie et les taux de croissance de six especes de coraux marins d'eau profonde recoltees sur la pente continentale de Terre-Neuve et du Labrador, a des profondeurs de 400 m a 900 m. Les Coraux bambous (Acanella arbuscula, Keratoisis ornata) et antipathariens (Stauropathes arctica) secretent des anneaux de croissance concentriques sur leur squelette axial et il est demontre que chez K. ornata et S. arctica ces anneaux se forment annuellement. Ces especes possedent les taux de croissance radiale les plus bas, de 33 [+ or -] 11 [micro]m x [an.sup.-1] a 75 [+ or -] 11 [micro]m x [an.sup.1]. Primnoa resedaeformis et Paramuricea spp. ont des taux de croissance radiale plus eleves, 83 [+ or -] 6 [micro]m x [an.sup.-1] a 215 [+ or -] 37 [micro]m x [an.sup.-1]. Paragorgia arborea presente le taux de croissance radiale le plus eleve, 830 [+ or -] 120 [micro]m x [an.sup.-1]. Les taux de croissance axiale varient de 0,56 [+ or -] 0,05 cm x [an.sup.-1] chez un specimen de Paramuricea spp. a 2,61 [+ or -] 0,45 cm x [an.sup.-1] chez un specimen de P. resedaeformis. Les durees de vie vont de 18 [+ or -] 4 annees chez un P. resedaeformis recolte vivant a 200 [+ or -] 30 ans pour un specimen subfossile de K. ornata. Puisque tous les coraux proviennent de regions soumises a une peche intensive, il est vraisemblable que les distributions d'age favorisent les colonies plus petites et plus jeunes. La recuperation des coraux marins d'eau profonde des dommages infliges par la peche prendra des decennies et meme des siecles. [Traduit par la Redaction], Introduction In recent years there has been increasing interest in the ecology and biology of deep-sea or cold-water coral ecosystems (Freiwald and Roberts 2005; Roberts et al. 2006). Off eastern [...]

The trophic behavior of some deep-sea Newfoundland cold-water corals was explored using fatty acid (FA) and lipid profiles. No significant effect of geographic location and/or depth was identified in lipid or FA composition. However, differences were detected between and within taxon groups in hexa- or octocoral subclasses. Phospholipids constituted the main lipid class in all groups except black-thorny corals which had less structural lipids likely due to their morphology (stiff axes) and slower growth rates. Within each subclass, major differences in the identity of dominant FAs were detected at the order level, whereas differences between species and taxon groups of the same order were mainly driven by a variation in proportions of the dominant FA. Soft corals and gorgonians (Order Alcyonacea) were close in composition and are likely relying on phytodetritus resulting from algae, macrophytes and/or foraminifera, while sea pens (Order Pennatulacea) seem to consume more diatoms and/or herbivorous zooplankton with the exception of Pennatula sp. In the hexacoral subclass, black-thorny corals (Stauropathes arctica) differed significantly from the stony-cup corals (Flabellum alabastrum); S. arctica was seemingly more carnivorous (zooplankton markers) than F. alabastrum, which appears omnivorous (phyto- and zooplankton markers). Our results suggest that deep-sea corals are not as opportunistic as expected but have some selective feeding associated with taxonomy. [ABSTRACT FROM AUTHOR]

Coral cover on Caribbean reefs has declined rapidly since the early 1980's. Diseases have been a major driver, decimating communities of framework building Acropora and Orbicella coral species, and reportedly leading to the emergence of novel coral assemblages often dominated by domed and plating species of the genera Agaricia, Porites and Siderastrea. These corals were not historically important Caribbean framework builders, and typically have much smaller stature and lower calcification rates, fuelling concerns over reef carbonate production and growth potential. Using data from 75 reefs from across the Caribbean we quantify: (i) the magnitude of non-framework building coral dominance throughout the region and (ii) the contribution of these corals to contemporary carbonate production. Our data show that live coral cover averages 18.2% across our sites and coral carbonate production 4.1 kg Ca CO3 m−2 yr−1. However, non-framework building coral species dominate and are major carbonate producers at a high proportion of sites; they are more abundant than Acropora and Orbicella at 73% of sites; contribute an average 68% of the carbonate produced; and produce more than half the carbonate at 79% of sites. Coral cover and carbonate production rate are strongly correlated but, as relative abundance of non-framework building corals increases, average carbonate production rates decline. Consequently, the use of coral cover as a predictor of carbonate budget status, without species level production rate data, needs to be treated with caution. Our findings provide compelling evidence for the Caribbean-wide dominance of non-framework building coral taxa, and that these species are now major regional carbonate producers. However, because these species typically have lower calcification rates, continued transitions to states dominated by non-framework building coral species will further reduce carbonate production rates below 'predecline' levels, resulting in shifts towards negative carbonate budget states and reducing reef growth potential. [ABSTRACT FROM AUTHOR]