The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean

Turf algae are multispecies communities of small marine macrophytes that are becoming a dominant component of coral reef communities around the world. To assess the impact of turf algae on corals, we investigated the effects of increased nutrients (eutrophication) on the interaction between the Caribbean coral Montastraea annularis and turf algae at their growth boundary. We also assessed whether herbivores are capable of reducing the abundance of turf algae at coral-algae boundaries. We found that turf algae cause visible (overgrowth) and invisible negative effects (reduced fitness) on neighbouring corals. Corals can overgrow neighbouring turf algae very slowly (at a rate of 0.12 mm 3 wk−1) at ambient nutrient concentrations, but turf algae overgrew corals (at a rate of 0.34 mm 3 wk−1) when nutrients were experimentally increased. Exclusion of herbivores had no measurable effect on the rate turf algae overgrew corals. We also used PAM fluorometry (a common approach for measuring of a colony's “fitness”) to detect the effects of turf algae on the photophysiology of neighboring corals. Turf algae always reduced the effective photochemical efficiency of neighbouring corals, regardless of nutrient and/or herbivore conditions. The findings that herbivores are not capable of controlling the abundance of turf algae and that nutrient enrichment gives turf algae an overall competitive advantage over corals together have serious implications for the health of Caribbean coral reef systems. At ambient nutrient levels, traditional conservation measures aimed at reversing coral-to-algae phase shifts by reducing algal abundance (i.e., increasing herbivore populations by establishing Marine Protected Areas or tightening fishing regulations) will not necessarily reduce the negative impact of turf algae on local coral communities. Because turf algae have become the most abundant benthic group on Curaçao (and likely elsewhere in the Caribbean), new conservation strategies are required to mitigate their negative impact on coral communities

Astro-WISE: Chaining to the Universe

The recent explosion of recorded digital data and its processed derivatives threatens to overwhelm researchers when analysing their experimental data or when looking up data items in archives and file systems. While current hardware developments allow to acquire, process and store 100s of terabytes of data at the cost of a modern sports car, the software systems to handle these data are lagging behind. This general problem is recognized and addressed by various scientific communities, e.g., DATAGRID/EGEE federates compute and storage power over the high-energy physical community, while the astronomical community is building an Internet geared Virtual Observatory, connecting archival data. These large projects either focus on a specific distribution aspect or aim to connect many sub-communities and have a relatively long trajectory for setting standards and a common layer. Here, we report "first light" of a very different solution to the problem initiated by a smaller astronomical IT community. It provides the abstract "scientific information layer" which integrates distributed scientific analysis with distributed processing and federated archiving and publishing. By designing new abstractions and mixing in old ones, a Science Information System with fully scalable cornerstones has been achieved, transforming data systems into knowledge systems. This break-through is facilitated by the full end-to-end linking of all dependent data items, which allows full backward chaining from the observer/researcher to the experiment. Key is the notion that information is intrinsic in nature and thus is the data acquired by a scientific experiment. The new abstraction is that software systems guide the user to that intrinsic information by forcing full backward and forward chaining in the data modelling.Comment: To be published in ADASS XVI ASP Conference Series, 2006, R. Shaw, F. Hill and D. Bell, ed

Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships

Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These are Bryopsidella neglecta (Berthotd) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck, Hincksia onslowensis (Amsler et Kapraun)P.C. Silva, Syringoderma floridana Henry, Peyssonnelia harveyana J. Agardh, Cryptonemia seminervis(C. Agardh) J. Agardh, Botryodadia wynnei Ballantine, Gloiocladia blomquistii (Searles) R. E.Norris, PIahchrysis peltata (W. R. Taylor) P. Huv4 et H. Huv4, Leptofauchea brasiliensis Joly, and Sarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae,support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions

Effects of competition on pattern formation in the rock-paper-scissors game

We investigate the impact of cyclic competition on pattern formation in the rock-paper-scissors game. By separately considering random and prepared initial conditions, we observe a critical influence of the competition rate $p$ on the stability of spiral waves and on the emergence of biodiversity. In particular, while increasing values of $p$ promote biodiversity, they may act detrimental on spatial pattern formation. For random initial conditions, we observe a phase transition from biodiversity to an absorbing phase, whereby the critical value of mobility grows linearly with increasing values of $p$ on a log-log scale, but then saturates as $p$ becomes large. For prepared initial conditions, we observe the formation of single-armed spirals, but only for values of $p$ that are below a critical value. Once above, the spirals break up and form disordered spatial structures, mainly because of the percolation of vacant sites. Thus, there exists a critical value of the competition rate $p_{c}$ for stable single-armed spirals in finite populations. Importantly though, $p_{c}$ increases with increasing system size, because noise reinforces the disintegration of ordered patterns. In addition, we also find that $p_{c}$ increases with the mobility. These phenomena are reproduced by a deterministic model that is based on nonlinear partial differential equations. Our findings indicate that competition is vital for the sustenance of biodiversity and emergence of pattern formation in ecosystems governed by cyclical interactions.Comment: 7 two-column pages, 7 figures; accepted for publication in Physical Review

Pre-therapy fasting slows epithelial turnover and modulates the microbiota but fails to mitigate methotrexate-induced gastrointestinal mucositis

BACKGROUND: Recent findings by Tang et al. (2020) show dietary restriction (30%, 2 weeks) prevents methotrexate-induced mortality by modulation of the microbiota, specifically the expansion of Lactobacillus. While fundamentally insightful, upscaling this schedule is a major obstacle to clinical uptake. Here, we evaluate a safe and clinically achievable schedule of pre-therapy fasting for 48 h on microbiota composition, body composition and intestinal proliferation, and assess its impact on the severity of methotrexate-induced gastrointestinal mucositis using a validated preclinical rat model. METHODS: Age- and weight-matched male Wistar rats were treated with a sublethal dose of 45 mg/kg methotrexate with or without pre-therapy fasting. The impact of acute fasting on epithelial proliferation, body composition and the microbiota was assessed using plasma citrulline, Ki67 immunohistochemistry, miniSpec and 16S rRNA sequencing. The severity of gastrointestinal mucositis was evaluated using plasma citrulline and body weight. RESULTS: Whilst pre-therapy fasting slowed epithelial proliferation and increased microbial diversity and richness, it also induced significant weight loss and was unable to attenuate the severity of mucositis in both age- and weight-matched groups. In contrast to Tang et al., we saw no expansion of Lactobacillus following acute fasting. CONCLUSIONS: Our findings suggest that the beneficial effects of acute fasting are masked by the detrimental effects on body weight and composition and lacking influence on Lactobacillus. Future studies should consider alternative fasting schedules or aim to induce comparable microbial and mucosal manipulation without compromising body composition using clinically feasible methods of dietary or microbial intervention

Fasting before living-kidney donation:effect on donor well-being and postoperative recovery: study protocol of a multicenter randomized controlled trial

BACKGROUND: One of the main effectors on the quality of life of living-kidney donors is postoperative fatigue. Caloric restriction (CR) and short-term fasting (STF) are associated with improved fitness and increased resistance to acute stress. CR/STF increases the expression of cytoprotective genes, increases immunomodulation via increased anti-inflammatory cytokine production, and decreases the expression of pro-inflammatory markers. As such, nutritional preconditioning by CR or STF represents a non-invasive and cost-effective method that could mitigate the effects of acute surgery-induced stress and postoperative fatigue. To investigate whether preoperative STF contributes to a reduction in fatigue after living-kidney donation, a randomized clinical trial is indicated. METHODS: We aim to determine whether 2.5 days of fasting reduces postoperative fatigue score in subjects undergoing living-kidney donation. In this randomized study, the intervention group will follow a preoperative fasting regime for 2.5 days with a low-dose laxative, while the control group will receive standard care. The main study endpoint is postoperative fatigue, 4 weeks after living-kidney donation. Secondary endpoints include the effect of preoperative fasting on postoperative hospital admission time, the feasibility of STF, and the postoperative recovery of donor and recipient kidney function. This study will provide us with knowledge of the feasibility of STF and confirm its effect on postoperative recovery. DISCUSSION: Our study will provide clinically relevant information on the merits of caloric restriction for living-kidney donors and recipients. We expect to reduce the postoperative fatigue in living-kidney donors and improve the postoperative recovery of living-kidney recipients. It will provide evidence on the clinical merits and potential caveats of preoperative dietary interventions. TRIAL REGISTRATION: Netherlands Trial Register NL9262. EudraCT 2020-005445-16. MEC Erasmus MC MEC-2020-0778. CCMO NL74623.078.21 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-021-05950-x

The stellar content, metallicity and ionization structure of HII regions

Observations of infrared fine-structure lines provide direct information on the metallicity and ionization structure of HII regions and indirectly on the hardness of the radiation field ionizing these nebulae. We have analyzed a sample of Galactic and Magellanic Cloud HII regions observed by the Infrared Space Observatory (ISO) to examine the interplay between stellar content, metallicity and the ionization structure of HII regions. The observed [SIV]10.5/[SIII]18.7 mum and [NeIII]15.5/[NeII]12.8 mum line ratios are shown to be highly correlated over more than two orders of magnitude. We have compared the observed line ratios to the results of photoionization models using different stellar energy distributions. The derived characteristics of the ionizing star depend critically on the adopted stellar model as well as the (stellar) metallicity. We have compared the stellar effective temperatures derived from these model studies for a few well-studied HII regions with published direct spectroscopic determinations of the spectral type of the ionizing stars. This comparison supports our interpretation that stellar and nebular metallicity influences the observed infrared ionic line ratios. We can explain the observed increase in degree of ionization, as traced by the [SIV]\[SIII] and [NeIII]\[NeII] line ratios, by the hardening of the radiation field due to the decrease of metallicity. The implications of our results for the determination of the ages of starbursts in starburst galaxies are assessed.Comment: 9 pages; accepted for publication in A&A; figure 3 modifie

Three-micron spectra of AGB stars and supergiants in nearby galaxies

The dependence of stellar molecular bands on the metallicity is studied using infrared L-band spectra of AGB stars (both carbon-rich and oxygen-rich) and M-type supergiants in the Large and Small Magellanic Clouds (LMC and SMC) and in the Sagittarius Dwarf Spheroidal Galaxy. The spectra cover SiO bands for oxygen-rich stars, and acetylene (C2H2), CH and HCN bands for carbon-rich AGB stars. The equivalent width of acetylene is found to be high even at low metallicity. The high C2H2 abundance can be explained with a high carbon-to-oxygen (C/O) ratio for lower metallicity carbon stars. In contrast, the HCN equivalent width is low: fewer than half of the extra-galactic carbon stars show the 3.5micron HCN band, and only a few LMC stars show high HCN equivalent width. HCN abundances are limited by both nitrogen and carbon elemental abundances. The amount of synthesized nitrogen depends on the initial mass, and stars with high luminosity (i.e. high initial mass) could have a high HCN abundance. CH bands are found in both the extra-galactic and Galactic carbon stars. None of the oxygen-rich LMC stars show SiO bands, except one possible detection in a low quality spectrum. The limits on the equivalent widths of the SiO bands are below the expectation of up to 30angstrom for LMC metallicity. Several possible explanations are discussed. The observations imply that LMC and SMC carbon stars could reach mass-loss rates as high as their Galactic counterparts, because there are more carbon atoms available and more carbonaceous dust can be formed. On the other hand, the lack of SiO suggests less dust and lower mass-loss rates in low-metallicity oxygen-rich stars. The effect on the ISM dust enrichment is discussed.Comment: accepted for A&

Global Phylogenomic Assessment of \u3ci\u3eLeptoseris\u3c/i\u3e and \u3ci\u3eAgaricia\u3c/i\u3e Reveals Substantial Undescibed Diversity at Mesophotic Depths

Background: Mesophotic coral communities are increasingly gaining attention for the unique biological diversity they host, exemplified by the numerous mesophotic fish species that continue to be discovered. In contrast, many of the photosynthetic scleractinian corals observed at mesophotic depths are assumed to be depth-generalists, with very few species characterised as mesophotic-specialists. This presumed lack of a specialised community remains largely untested, as phylogenetic studies on corals have rarely included mesophotic samples and have long suffered from resolution issues associated with traditional sequence markers. Results: Here, we used reduced-representation genome sequencing to conduct a phylogenomic assessment of the two dominant mesophotic genera of plating corals in the Indo-Pacific and Western Atlantic, respectively, Leptoseris and Agaricia. While these genome-wide phylogenies broadly corroborated the morphological taxonomy, they also exposed deep divergences within the two genera and undescribed diversity across the current taxonomic species. Five of the eight focal species consisted of at least two sympatric and genetically distinct lineages, which were consistently detected across different methods. Conclusions: The repeated observation of genetically divergent lineages associated with mesophotic depths highlights that there may be many more mesophotic-specialist coral species than currently acknowledged and that an urgent assessment of this largely unstudied biological diversity is warranted