Description: Ocean manipulation to mitigate climate change may harm deep-sea ecosystems

Description: Highlights • Probeebei mirabilis with or without anemone as indicator of changed environment. • 26 years after disturbance population densities changed significantly. • Possible delayed response to anthropogenic disturbance experiment. • Need for long-term (〉30 yrs) monitoring surveys post-disturbance in the abyss. The deep Peru Basin is characterised by a unique abyssal scavenging community featuring large numbers of hermit crabs (Probeebei mirabilis, Decapoda, Crustacea). These are atypical hermit crabs, not carrying a shell, but on some occasions carrying an anemone (Actiniaria). The reason why some hermit crabs carry or not carry anemones is thought to be indicative of a changed environment, outweighing the cost/benefit of their relationship. Here we present the temporal variation of abundances of P. mirabilis with and without anemones, spanning more than two decades, following a benthic impact experiment. An overall decrease in hermit crab densities was observed, most noticeable and significant after 26 years and characterised by a loss of Actiniaria on the Probeebei mirabilis' pleon. Whether this is a delayed response to the benthic impact experiment carried out 26 years’ prior or a natural variation in the population remains to be corroborated by an extension of the time-series. Attention is drawn to the limitations of our knowledge over time and space of the abyssal community dynamics and the urgent necessity to fill in these gaps prior to any type of deep-sea exploitation.

Description: We report the results of an aquaria-based experiment testing the effects of low oxygen and suspended particles generated during a potential mining activities accident on the juveniles of the vent mussel Bathymodiolus azoricus. Mussels were collected from the Lucky Strike hydrothermal vent field (Azores, NE Atlantic) at 1700 m water depth in 2021. Mussels were maintained in 1 l aquaria and exposed to four experimental treatments for a period of two weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments and normal seawater oxygen ); (2) low oxygen (difference of 30 µmol from the normal oxygen concentration); (3) suspended polymetallic sulphide (PMS) particles; (4) Low oxygen + suspended polymetallic sulphide (PMS) particles. PMS particles were obtained by grinding PMS inactive chimney rocks collected at the hydrothermal vent field Lucky Strike. Particles types were in concentration of 420 mg/l on day 8 and day 11. The putative effects of low oxygen, PMS particles, and the cumulative effect(s) were evaluated through measurements of mussel physiological responses at the organism level (respiration derived from oxygen consumption, ammonium excretion derived from (NH3+NH4+ fluxes).

Description: We report the results of an aquaria-based experiment testing the effects of low oxygen and suspended particles generated during a potential mining activities accident on the juveniles of the vent mussel Bathymodiolus azoricus. Mussels were collected from the Lucky Strike hydrothermal vent field (Azores, NE Atlantic) at 1700 m water depth in 2021. Mussels were maintained in 1 l aquaria and exposed to four experimental treatments for a period of two weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments and normal seawater oxygen ); (2) low oxygen (difference of 30 µmol from the normal oxygen concentration); (3) suspended polymetallic sulphide (PMS) particles; (4) Low oxygen + suspended polymetallic sulphide (PMS) particles. PMS particles were obtained by grinding PMS inactive chimney rocks collected at the hydrothermal vent field Lucky Strike. Particles types were in concentration of 420 mg/l on day 8 and day 11. The putative effects of low oxygen, PMS particles, and the cumulative effect(s) were evaluated through measurements of bulk mussel tissue samples by stable isotopes and elemental analyses, as follows: Continuous flow isotope mass spectrometry (CF-IRMS) was performed on a SerconHydra 20–22 (Sercon, UK) and Isoprime IRMS stable isotope ratio mass spectrometer, coupled to a EuroEA (EuroVector, Italy) elemental analyser for online sample preparation by Dumas-combustion. Delta Calculation was performed according to δ = [(Rsample – Rstandard)/Rstandard]*1000, where R is the ratio between the heavier isotope and the lighter one. δ15 NAir values are referred to air, δ13 CVPDB values are referred to PDB (Pee Dee Belemnite), and δ18O are referred to -VSMOW. The reference materials used were IAEA C3, IAEA CH7; IAEA 600; IAEA N1 and N2; IAEA 601 and IAEA 602. EuroEA (EuroVector, Italy) elemental analyser was used for online sample preparation by Dumas-combustion. For the elemental analyses the Certified Reference Materials were Sulfanilamide for C, N, H, S and Atropine for O.

Description: Trait-based approaches that complement taxonomic-based studies have increased in popularity among the scientific community over the last decades. The collection of biological and ecological characteristics of species (i.e., traits) provides insight into species and ecosystem vulnerability to environmental and anthropogenic changes, as well as ecosystem functioning. While most of the available trait databases to date contain essential information to understand the functional diversity of a taxonomic group or functional group based on size, the FUN Azores trait database has an ecosystem-based approach that provides a comprehensive assessment of diverse fauna (meio-, macro-, and megafauna) from benthic and pelagic environments in the Azores Marine Park; including ridges, seamounts, and hydrothermal vents. We used a collaborative approach involving 30 researchers with different expertise to develop the trait database; which contains compiled data on 14 traits representing morphological, behavioral, and life history characteristics for 1210 species, across 10 phyla.

Description: This database contains functional traits of target and non-target fish species (Actinopterygii and Elasmobranchii) from the Azores archipelago, Portugal. The included traits are reproductive guilds, body shape, position in water column, mean temperature preference (ᵒC), generation time (years), maximum depth (m), trophic position, growth coefficient (K), size at first maturity (cm), food consumption (Q/B), fecundity, and maximum body size (cm). The traits scores were assigned based on databases provided by FishBase (Froese and Pauly, 2023), and Trindade-Santos et al. (2020). Additionally, relevant literature was also utilized. These traits were selected based on biological and ecological knowledge of species critical for ecological processes in marine ecosystems, as well as data availability. The selected traits are associated with fish functions including habitat use, locomotion, feeding, and life history.