Biology subjects

Montilla, L. M.

Publications and source records attributed to Montilla, L. M..

5 recordsLinked to original sources

bioRxiv2025

Nitrification in a seagrass-sponge association

AO_SCPLOWBSTRACTC_SCPLOWIn the Mediterranean Sea, the demosponge Chondrilla nucula can occur in close association with the native seagrass Posidonia oceanica. C. nucula harbors a diverse and abundant microbial community, including potential nitrifiers. Thus, the sponge may contribute to the nitrogen (N) demand of the seagrass holobiont. In this study, we investigated potential nitrification rates (PNR) and inorganic N fluxes within this association at a site where C. nucula covered 18 {+/-} 3 % of the seagrass meadow area, during plant growth (spring) and senescence (autumn). Using incubation experiments with 15N-labeled ammonium, we measured PNR and inorganic N of the seagrass-sponge association, and of sponge and seagrass independently, under light and dark conditions. We supplemented these experiments with 16s rRNA gene amplicon sequencing to characterize the microbial community of the sponge. PNR was exclusively measured when the sponge was present (alone or in association with the seagrass). PNR was highest in the dark and when C. nucula was associated with the seagrass, ranging from 21 {+/-} 7 to 267 {+/-} 33 nmol N g DW-1 h-1 in spring and autumn, respectively. Sponge-mediated PNR can support 8% of the N demand of the P. oceanica holobiont during growth and 47 % during senescence. We identified key nitrifying bacterial and archaeal groups as members of the sponges microbial community. While C. nucula released inorganic N, potentially sustaining the seagrass, it benefitted from dissolved organic carbon released by P. oceanica. These results suggest that the interaction between C. nucula and P. oceanica is mutually beneficial, ultimately supporting and stabilizing the seagrass ecosystem.

ecology↗

bioRxiv2024

Reciprocal nutritional benefits in a sponge-seagrass association

Sponges commonly form associations within seagrass meadows, but their potential impact on seagrass productivity and nutrient cycles remains poorly understood. This study investigates the association between the demosponge Chondrilla nucula and the Mediterranean seagrass Posidonia oceanica in two sampling occasions during the plant growth (spring) and senescence (autumn) seasons at a small inlet near Naples, Italy, where the sponge grows conspicuously within the seagrass bed. We found a non-linear relationship between the benthic cover of the sponge and the seagrass, with higher C. nucula cover linked to intermediate P. oceanica cover, suggesting spatial dependence. P. oceanica showed higher net primary production (NPP) in spring, while C. nucula was net heterotrophic in spring but exhibited slightly positive NPP in autumn. NPP remained stable when the two organisms were associated, regardless of the season. C. nucula consistently contributed inorganic nutrients to the association in the form of phosphate, ammonium, and substantial nitrate, recycling nutrients that potentially benefited P. oceanica in its growth season. In return, the seagrass consistently provided dissolved organic carbon, which aided sponge nutrition in spring. These findings suggest reciprocal benefits in the interaction between C. nucula and P. oceanica, with nutrient exchange facilitating a facultative mutualism that potentially supports and stabilizes the productivity of the seagrass ecosystem. SIGNIFICANCE STATEMENTThis study provides a novel exploration of the reciprocal interactions between the demosponge Chondrilla nucula and the Mediterranean seagrass Posidonia oceanica, revealing a facultative mutualism mediated by nutrient exchange. Our findings show a non-linear spatial dependence between sponge and seagrass cover and demonstrate the sponges substantial contributions of inorganic nutrients (phosphate, ammonium and conspicuous nitrate) to the seagrass, particularly during its productive spring season. In return, P. oceanica supplies dissolved organic matter, aiding sponge nutrition. This study uniquely quantifies these reciprocal nutrient exchanges across the plant growth and senescence seasons, demonstrating how such interactions stabilize net primary production and support ecosystem functioning. These insights address a critical gap in understanding the role of sponge-seagrass associations in nutrient cycling, highlighting their significance for the resilience, productivity, and metabolic balance of coastal ecosystems under changing environmental conditions.

ecology↗

bioRxiv2023

Accelerated Nitrogen Cycling on Seagrass Leaves in a High-CO2 World

Seagrass meadows form highly productive and diverse ecosystems in coastal areas worldwide, where they are increasingly exposed to ocean acidification (OA). Efficient nitrogen (N) cycling and uptake are essential to maintain plant productivity, but the effects of OA on N transformations in these systems are poorly understood. Here we show that complete N cycling occurs on leaves of the Mediterranean seagrass Posidonia oceanica, with OA affecting both N gain and loss while the prokaryotic community structure remains largely unaffected. Daily leaf-associated N2 fixation contributed to 35% of the plants N demand under ambient pH, whereas it contributed to 45% under OA. Nitrification potential was only detected under OA, and N-loss via N2 production increased, although the balance remained decisively in favor of enhanced N gain. Our work highlights the role of the N-cycling microbiome in seagrass adaptation to OA, with key N transformations accelerating towards increased N gain.

ecology↗

bioRxiv2019

Transects, quadrats, or points? What is the best combination to get a precise estimation of a coral community?

The characteristics of coral reef sampling and monitoring are highly variable, with numbers of units and sampling effort varying from one study to another. Numerous works have been carried out to determine an appropriate effect size through statistical power, however, always from a univariate perspective. In this work, we used the pseudo multivariate dissimilarity-based standard error (MultSE) approach to assess the precision of sampling scleractinian coral assemblages in reefs of Venezuela between 2017 and 2018 when using different combinations of number of transects, quadrats and points. For this, the MultSE of 36 sites previously sampled was estimated, using four 30m-transects with 15 photo-quadrats each and 25 random points per quadrat. We obtained that the MultSE was highly variable between sites and is not correlated with the univariate standard error nor with the richness of species. Then, a subset of sites was re-annotated using 100 uniformly distributed points, which allowed the simulation of different numbers of transects per site, quadrats per transect and points per quadrat using resampling techniques. The magnitude of the MultSE stabilized by adding more transects, however, adding more quadrats or points does not improve the estimate. For this case study, the error was reduced by half when using 10 transects, 10 quadrats per transect and 25 points per quadrat. We recommend the use of MultSE in reef monitoring programs, in particular when conducting pilot surveys to optimize the estimation of the community structure.

ecology↗

bioRxiv2018

Analysis of 50 years of coral disease research visualized through the scope of network theory

Coral disease research encompasses five decades of undeniable progress. Since the first descriptions of anomalous signs, we have come to understand multiple processes and environmental drivers that interact with coral pathologies. To gain a better insight into the knowledge we already have, we explored how key topics in coral disease research have been related to each other using network analysis. We reviewed 719 papers and conference proceedings published from 1965 to 2017. From each study, four elements determined our network nodes: 1) studied disease(s); 2) host genus; 3) marine ecoregion(s) associated with the study site; and 4) research objectives. Basic properties of this network confirmed that there is a set of specific topics comprising the majority of research. The top five diseases, genera, and ecoregions studied accounted for over 48% of the research effort in all cases. The community structure analysis identified 15 clusters of topics with different degrees of overlap among them. These clusters represent the typical sets of elements that appear together for a given study. Our results show that while some coral diseases have been studied considering multiple aspects, the overall trend is for most diseases to be understood under a limited range of approaches, e.g. bacterial assemblages have been considerably studied in Yellow and Black band diseases while immune response has been better examined for the aspergillosis-Gorgonia system. Thus, our challenge in the near future is to identify and resolve potential gaps in order to achieve a more comprehensive progress on coral disease research.

ecology↗