Propagação clonal, conectividade e estrutura genetica em populações de Paramuricea clavata do Atlântico e Mediterrâneo

Doutoramento em Ciências do MarThe red gorgonian Paramuricea clavata is an engineering species, inhabiting rocky shore in the Mediterranean Sea and Portuguese coast of the Atlantic Ocean. The species was severely impacted by climatically induced mass mortality events in the NW Mediterranean. The general aim of the study was to investigate the genetic diversity of P. clavata in the Ligurian Sea (NW Mediterranean), a region highly impacted by past mass mortality events, and the Atlantic Ocean, where mass mortality was never observed due to generally lower water temperature. Microsatellites were used to study the contribution of clonal reproduction, connectivity pattern, genetic structure and diversity. Additionally one mitochondrial marker (Cytochrome Oxidase I) was used to compare the Atlantic and Mediterranean populations. The results revealed, that clonal propagation does not play an important role in P. clavata, since at four out of nine sites clones were not detected and the maximum prevalence of clones reached only 13%. The study failed to detect any genetic diversity loss in the P. clavata populations affected by mass mortality events. The migration pattern among sites affected by mass mortality and unaffected ones was described. The results confirmed that low larval dispersal capability in the red gorgonian may still be ecologically significant for population replenishment and persistence, enabling migration between local populations. This research has identified an important genetic break within the red gorgonian distribution. Both markers used in the present study, mtDNA and microsatellites, revealed the same discontinuity between the Mediterranean and Atlantic. Significant differences were found in the genetic diversity between the Mediterranean and Atlantic populations, with heterozygosity and allelic richness being slightly, but significantly, higher in the Mediterranean Sea, possibly as a result of colonization history or isolation of the Atlantic sites. The differences in genetic diversity were also detected between deep and shallow populations. Allelic richness increase with depth, being lower in the shallow, less stable populations due to past mortality events induced by warming and other interacting factors and higher in deeper, stable populations.The results should prove to be particularly valuable for the conservation of soft corals communities and thus the overall marine biodiversity.A gorgónia vermelha, Paramuricea clavata, é uma espécie engenheira que habita costas e recifes rochosos do Mediterrâneo e do Atlântico ao longo da costa de Portugal, a profundidades que variam entre 15 e os 80 m. Esta espécie foi severamente afetada, no Mediterrâneo NO, por eventos de mortalidade induzidos por variações climáticas recentes. O objetivo geral deste estudo foi a investigação da diversidade genética de P. clavata no Mar da Ligúria (Mediterrâneio NO), uma região altamente impactada por eventos de mortalidade em massa causados por temperaturas elevadas, e no Atlântico, onde mortalidade em massa nunca foi observada em consequência de temperaturas genericamente mais baixas. Foram utilizados microsatélites para o estudo da contribuição da reprodução clonal, padrões de conectividade, estrutura genética e diversidade genética. Adicionalmente, um marcador mitocondrial (Cytochrome Oxidase I) foi usado para comparar as populações do Atlântico e do Mediterrâneo. Os resultados revelaram que a propagação clonal não desempenha um papel importante em P. clavata, uma vez que em quatro dos nove sítios não foram detetados clones e que a máxima prevalência de clones detetada atingiu apenas 13%. No entanto, a prevalência de clones detectada no presente estudo foi maior do que o previamente relatado. O estudo não conseguiu detetar qualquer perda de diversidade genética nas populações de P. clavata afetadas por eventos de mortalidade em massa. Foi possível descrever o padrão de migração entre os sítios afetados pela mortalidade em massa e os não afetados. Os resultados confirmaram que a baixa capacidade de dispersão larvar na gorgónia vermelha pode ainda ser ecologicamente significante para a recolonização e persistência populacional, permitindo a migração entre populações locais. A troca de larvas foi mais comum entre recifes separados por 200-300m, mas também foi detectada entre locais separados por 20 km. Os dados indicaram ainda migrações comuns entre recifes localizados a menores profundidades, impactados por mortalidade em massa, e recifes mais profundos, não impactados, do mesmo local. A presente investigação identificou uma importante descontinuidade genética na distribuição da gorgónia vermelha, com ambos os marcadores utilizados no estudo, mtDNA e microsatélites, revelando a mesma descontinuidade entre o Mediterrâneo e o Atlântico. Foram também encontradas diferenças significativas na diversidade genética entre o Mediterrâneo e as populações do Oceano Atlântico, com a heterozigosidade e a riqueza alélica ligeiramente, mas significativamente, mais elevadas no Mediterrâneo, possivelmente como resultado da história da colonização ou isolamento dos locais do Atlântico. Finalmente, foram ainda detectadas diferenças na diversidade genética entre as populações superficiais e mais profundas. A riqueza alélica foi menor nas populações menos profundas, menos estáveis devido a eventos de mortalidade induzidos pelo aquecimento e por outros fatores, e maior nas populações mais profundas e estáveis. Estes resultados devem revelar-se particularmente valiosos para a conservação de comunidades de gorgónias e assim a biodiversidade marinha global.La gorgonia rossa Paramuricea clavata è una ‘engineering species’, vive sui fondali rocciosi del Mediterraneo e della costa portoghese dell’Oceano Atlantico. La specie è stata severamente impattata da eventi di mortalità di massa indotti dal CC nel Mediterraneo nord-occidentale. Lo scopo dello studio è stato di indagare la diversità genetica di P. clavata nel Mar Ligure (Mediterraneo nord-occidentale), una regione fortemente impattata da eventi di mortalità, e nell’Oceano Atlantico, dove eventi di mortalità non sono mai stati registrati grazie a valori di temperatura dell’acqua generalmente più bassi. Per studiare il contributo della riproduzione clonale, i pattern di connettività, la struttura e la diversità genetica sono stati usati i microsatelliti. In aggiunta, un marcatore mitocondriale (Cytochrome Oxidase I) è stato utilizzato per confrontare le popolazioni atlantiche con quelle mediterranee. I risultati hanno mostrato che la propagazione clonale non gioca un ruolo importante in P. clavata, in quanto in quattro siti su nove non sono stati individuati cloni e la predominanza massima di cloni ha totalizzato solo il 13%. Lo studio non ha riscontrato perdita di diversità genetica nelle popolazioni di P. clavata colpite da eventi di mortalità. Sono stati descritti i pattern di migrazione tra siti colpiti da mortalità e quelli non colpiti. I risultati hanno confermato che la bassa dispersione larvale nella gorgonia rossa può essere ancora ecologicamente significativa per il rifornimento e la persistenza di popolazioni, favorendo la migrazione tra popolazioni locali. Questa ricerca ha identificato un importante break genetico nella distribuzione della gorgonia rossa. Entrambi i marker usati in questo studio, mtDNA e microsatelliti, hanno rivelato la stessa discontinuità tra Mediterraneo ed Atlantico. Differenze significative sono state riscontrate nella diversità genetica tra popolazioni mediterranee e atlantiche, con eterozigosità e ricchezza allelica leggermente, ma significativamente più alte nel Mediterraneo, probabilmente come risultato della storia di colonizzazione o isolamento dei siti atlantici. Le differenze nella diversità genetica sono state riscontrate anche tra popolazioni profonde e superficiali. La ricchezza allelica aumenta con la profondità, risultando più bassa nelle popolazioni più superficiali, meno stabili a causa degli eventi di mortalità indotti dal riscaldamento e da altri fattori interagenti, e più alta nelle popolazioni più profonde e relativamente più stabili. I risultati sono di particolare interesse per la conservazione delle comunità di coralli molli e quindi nel complesso per la biodiversità marina

Low clonal propagation in Atlantic and Mediterranean populations of the red gorgonian Paramuricea clavata (Octocorallia)

Clonal propagation is a common feature of benthic marine organisms. In the present study, we investigated the contribution of clonal reproduction in the red gorgonian Paramuricea clavata. Mediterranean populations of P. clavata were severely affected by mass mortality events caused by increased water temperature in 1999 and 2003. The populations are characterized by slow growth and episodic recruitment, but after the observed mortalities, an unexpectedly high recovery rate was observed in the severely affected populations from the Ligurian Sea, NW Mediterranean. Ten years after the last mortality event, we investigated the contribution of clonal propagation in populations from the Ligurian Sea, where some populations were highly affected by mass mortality events, and from the Atlantic, where mortality was never observed. All individuals were genotyped for nine microsatellite loci. The contribution of clonal reproduction varied from 0% to 13% and did not differ significantly between affected and unaffected populations. We confirm by using genetic markers that clonal propagation in P. clavata is not common, and that the contribution of clones is too low to play an important role in red gorgonian reproduction and cannot contribute to population recovery at sites that have been affected by mass mortality events.Fundacao para a Ciencia e Tecnologia (FCT) under the COMPETE program - European Regional Development Fund [PTDC/BIA-BIC/114526/2009]; MARES Grant; Erasmus Mundus [FPA 2011-0016

Genetic diversity increases with depth in red gorgonian populations of the Mediterranean Sea and the Atlantic Ocean

In the ocean, the variability of environmental conditions found along depth gradients exposes populations to contrasting levels of perturbation, which can be reflected in the overall patterns of species genetic diversity. At shallow sites, resource availability may structure large, persistent and well-connected populations with higher levels of diversity. In contrast, the more extreme conditions, such as thermal stress during heat waves, can lead to population bottlenecks and genetic erosion, inverting the natural expectation. Here we examine how genetic diversity varies along depth for a long-lived, important ecosystem-structuring species, the red gorgonian, Paramuricea clavata.Agência financiadora CESAM UID/AMB/50017/2019 Portuguese Foundation for Science and Technology FEDER, within the PT2020 Partnership Agreement FEDER, within the Compete 2020 Pew Marine Fellowship (USA) National Geographic Channel through project Deep Reefs, a National Geographic/Waitt grant W153-11 InAqua Conservation Fund (Oceanario de Lisboa) European Regional Development Fund (COMPETE program) Portuguese Foundation for Science and Technology SFRH/BPD/111003/2015 CCMAR/Multi/04326/2013 UID/MAR/04292/2013 PTDC/BIA-BIC/114526/2009 MARES Grant Joint Doctorate programme under Erasmus Mundus by Ghent University FPA 2011-0016info:eu-repo/semantics/publishedVersio

The understorey of gorgonian forests in mesophotic temperate reefs

1. In the Mediterranean Sea, dense populations of the gorgonian Paramuricea clavata shape marine animal forests, characterizing the seascapes of coralligenous habitats. Despite concerns for its health, with several anthropogenic threats and recent mass mortality events, mainly triggered by thermal anomalies, the understorey of its forests and the ecological processes that they promote are still little known. Here, the abundance and composition of epibenthic assemblages inside and outside P. clavata forests were investigated across the central and western Mediterranean Sea, by applying a multifactorial sampling design. 2. In spite of the large variability in the structures of epibenthic assemblages at local and regional scales, the gorgonian understoreys share some common features, such as higher abundances of calcareous builder organisms and reduced invasion by the non\u2010indigenous alga Caulerpa cylindracea, compared with the adjacent unforested rocky bottoms. Paramuricea clavata showed non\u2010linear density\u2010dependent relationships with algal turfs and non\u2010encrusting algae belonging to the genus Peyssonnelia. Moreover, by entrapping benthic mucilaginous aggregates with their branches, these gorgonians risk topical necrotic lesions, but may reduce the suffocation risks for understorey organisms. 3. Overall, P. clavata forests may enhance bioconstruction processes and increase resistance and resilience of the benthic assemblages in the Mediterranean coralligenous habitats. This species and its forests, together with their understoreys, should be considered as essential elements of the ecology of the Mediterranean Sea, and therefore worthy of specific and effective protection measures. 4. Conservation strategies should reduce the risk of mechanical damage by regulating fishing activities, anchorages, and scuba diving where gorgonian forests are present. Moreover, when evident alterations are documented, restoration actions should be implemented to recover the integrity of gorgonian forests

Genetic diversity and local connectivity in the mediterranean red gorgonian coral after mass mortality events

Estimating the patterns of connectivity in marine taxa with planktonic dispersive stages is a challenging but crucial task because of its conservation implications. The red gorgonian Paramuricea clavata is a habitat forming species, characterized by short larval dispersal and high reproductive output, but low recruitment. In the recent past, the species was impacted by mass mortality events caused by increased water temperatures in summer. In the present study, we used 9 microsatellites to investigate the genetic structure and connectivity in the highly threatened populations from the Ligurian Sea (NW Mediterranean). No evidence for a recent bottleneck neither decreased genetic diversity in sites impacted by mass mortality events were found. Significant IBD pattern and high global F-ST confirmed low larval dispersal capability in the red gorgonian. The maximum dispersal distance was estimated at 20-60 km. Larval exchange between sites separated by hundreds of meters and between different depths was detected at each site, supporting the hypothesis that deeper subpopulations unaffected by surface warming peaks may provide larvae for shallower ones, enabling recovery after climatically induced mortality events

Mediterranean bioconstructions along the Italian coast

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning

High genetic differentiation of red gorgonian populations from the Atlantic Ocean and the Mediterranean Sea

<p>Patterns of genetic variation within a species may be used to infer past events in the evolutionary history of marine species. In the present study we aimed to compare the genetic diversity of the red gorgonian <i>Paramuricea clavata</i> in the Atlantic Ocean and the Mediterranean Sea. For genetic markers we used microsatellites and a mitochondrial gene fragment. Our results revealed a distinct genetic composition and diversity between the Mediterranean and the Atlantic. The Mediterranean samples had higher microsatellite heterozygosity, allelic richness and private allelic richness. The hypotheses that can explain these patterns are the isolation of Atlantic populations and/or a founder effect. Additionally, a clear difference was obtained from the mitochondrial locus, since sequences from Atlantic and Mediterranean samples diverged by 1%, which is high for soft corals.</p

Sampling sites in the Mediterranean.

<p>Reefs impacted by mass mortality events (in black) and healthy reefs (in white).</p

AMOVA.

<p>AMOVA.</p

Pairwise F_ST values.

<p>Pairwise F_ST values.</p