Ability to Swim (Not Morphology or Environment) Explains Interspecific Differences in Crinoid Arm Regrowth

Regrowth of body parts occurs in almost every phylum of the animal kingdom, but variation in this process across environmental, morphological, and behavioral gradients remains poorly understood. We examined regeneration patterns in feather stars – a group known for a wide range of morphologies and behaviors and up to a forty-fold difference in arm regeneration rates – and found that the variation in arm regeneration rates is best explained by swimming ability, not temperature, food supply, morphology (total number of arms and number of regenerating arms), or degree of injury. However, there were significant interactive effects of morphology on rates of regeneration of the main effect (swimming ability). Notably, swimmers grew up to three-fold faster than non-swimmers. The temperate feather star Florometra serratissima regenerated faster under warmer scenarios, but its rates fell within that of the tropical species suggesting temperature can account for intraspecific but not interspecific differences. We urge comparative molecular investigations of crinoid regeneration to identify the mechanisms responsible for the observed interspecific differences, and potentially address gaps in stem cell research

The CFOSAT Project : a cooperation to assess wave directional spectra and surface winds

International audienc

Seagrass blue carbon stocks in the German Baltic Sea

A total of 169 sediment cores (30 cm length; 5.5 cm inner diameter) were sampled in seagrass meadows (n = 110 cores) and nearby unvegetated sediments (n = 59 cores). Nine cores (with some exceptions) were collected at each site, from three sublocations: (1) in the high-density part of the meadow (“dense seagrass” hereafter), (2) low density or fringe of the meadow (“sparse seagrass” hereafter), and (3) adjacent unvegetated sediments at least 5 m from seagrass (“unvegetated”). Dense and sparse seagrass sublocations are collectively referred to as “seagrass-vegetated” sediments or sublocations. Sediment cores taken within the seagrass meadow were sampled at least 10 m apart from each other. Several biophysical parameters were collected alongside each core, including seawater depth, sediment grain size, current velocity at the seafloor, and seagrass complexity. The measure of “seagrass complexity” was defined as the product of seagrass canopy height and shoot density, to obtain the sum of leaf heights within a unit of area (in m/m2). Cores were collected between 1 and 5 m seawater depth manually via self-contained underwater breathing apparatus (SCUBA) divers pounding impact-resistant PVC tubes into the sediment with a rubber mallet. Sediment total Corg was determined using an Elemental Analyzer (EURO EA Elemental Analyzer)

The effects of primary and secondary bacterial exposure on the seahorse (Hippocampus erectus) immune response

Highlights: • Transcriptomic immune response assessments in seahorse (Hippocampus erectus). • Seahorses exposed in two phases to heat-killed Vibrio and Tenacibaculum strains. • Adaptive immune memory evidence (double-exposed) and increased naivety to Tenacibaculum. • Upregulated gene expression pertaining to potential innate ‘trained immunity’. • Trained immunity potential compensator for deduced MHC II loss of function. Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism

Substantial seagrass blue carbon pools in the southwestern Baltic Sea include relics of terrestrial peatlands

Seagrass meadows have a disproportionally high organic carbon (Corg) storage potential within their sediments and thus can play a role in climate change mitigation via their conservation and restoration. However, high spatial heterogeneity is observed in Corg, with wide differences seen globally, regionally, and even locally (within a seagrass meadow). Consequently, it is difficult to determine their contributions to the national remaining carbon dioxide (CO2) budget without introducing a large degree of uncertainty. To address this spatial heterogeneity, we sampled 20 locations across the German Baltic Sea to quantify Corg stocks and sources in Zostera marina seagrass-vegetated and adjacent unvegetated sediments. To predict and integrate the Corg inventory in space, we measured the physical (seawater depth, sediment grain size, current velocity at the seafloor, anthropogenic inputs) and biological (seagrass complexity) environments to determine regional and local drivers of Corg variation. Here, we show that seagrass meadows in Germany constitute a significant Corg stock, storing on average 7,785 g C/m2, 13 times greater than meadows from other parts of the Baltic Sea, and fourfold richer than adjacent unvegetated sediments. Stocks were highly heterogenous; they differed widely between (by 10-fold) and even within (by 3- to 55-fold) sites. Regionally, Corg was controlled by seagrass complexity, fine sediment fraction, and seawater depth. Autochthonous material contributed to 78% of the total Corg in seagrass-vegetated sediments, and the remaining 22% originated from allochthonous sources (phytoplankton and macroalgae). However, relic terrestrial peatland material, deposited approximately 6,000 years BP during the last deglaciation, was an unexpected and significant source of Corg. Collectively, German seagrasses in the Baltic Sea are preventing 8.14 Mt of future CO2 emissions. Because Corg is mostly produced on-site and not imported from outside the meadow boundaries, the richness of this pool may be contingent on seagrass habitat health. Disturbance of this Corg stock could act as a source of CO2 emissions. However, the high spatial heterogeneity warrants site-specific investigations to obtain accurate estimates of blue carbon and a need to consider millennial timescale deposits of Corg beneath seagrass meadows in Germany and potentially other parts of the southwestern Baltic Sea

Netto-Null-2050 Wegweiser - Strategische Handlungsempfehlungen und mögliche Wege für ein CO2-neutrales Deutschland bis 2050

Spätestens seit dem Pariser Klimaabkommen (UNFCCC, 2015) im Jahr 2015 ist Klimaschutz in aller Munde. Die aktuellen Erkenntnisse des Band 1 des 6. IPCC-Sachstandsberichts (IPCC, 2021) unterstreichen diese Notwendigkeit: Der Klimawandel ist menschengemacht. Schnelle CO2-Minderung ist notwendiger denn je. Von der lokalen über die EU bis zur globalen Ebene soll bis 2050 – oder sogar schon früher – die Null unterm Strich sein: Alle Emissionen von Kohlendioxid – und auch anderen Treibhausgasen – sind dann so weit wie nur möglich reduziert und die CO2-Konzentration in der Atmosphäre steigt nicht mehr an. Eines ist jedoch Fakt: Auf dem Weg dahin werden sich nicht alle CO2-Emissionen vermeiden lassen und auch am Ende bleiben CO2-Emissionen übrig. Wie reduzieren wir also CO2 und was machen wir mit dem „Rest“, um auf Null zu kommen? Genau darauf gibt dieser Bericht Antworten