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- A alga invasora Sargassum muticum e as macrófitas nativas do Sul de PortugalPublication . Paulo, D. S.; Santos, Rui; Silva, João; Engelen, AshwinA taxa de invasões biológicas marinhas tem vindo a aumentar desde o início do século 20. Desde então também a preocupação em compreender os impactos a nível económico e ecológico das espécies não nativas tem aumentado. O conhecimento da ecologia das espécies invasoras pode reduzir o seu impacto nas alterações provocadas nos ecossistemas e na interacção entre as espécies. A alga castanha Sargassum muticum (Yendo) Frensholt é considerada uma das mais agressivas entre as algas marinhas invasoras. Esta espécie originária do Japão foi detectada pela primeira vez na Europa em 1973, na costa sul de Inglaterra. Nos dias de hoje encontra-se distribuída por toda a Europa. Existe uma população estabelecida de S. muticum nos enclaves da zona intertidal do Parque Natural do Sudoeste Alentejano e Costa Vicentina (PNSACV), na costa sudoeste de Portugal, partilhando habitat com a alga castanha Cystoseira humilis. Recentemente foi detectada uma população subtidal de S. muticum no Parque Natural da Ria Formosa (PNRF), sul de Portugal, um sistema mesotidal dominado por três espécies de ervas marinhas: a intertidal Zostera noltii, e as subtidais Z. marina e Cymodocea nodosa. As respostas fotossintéticas da alga invasora e das macrófitas nativas foram comparadas sob as condições naturais de luz (0-1460 μmol m-2s-1) e temperatura (14, 18, 22 e 26ºC), de modo a determinar o potencial fotossintético da invasora. Para tal, amostras de S. muticum e C. humilis foram recolhidas nos enclaves de uma costa rochosa exposta na praia de Almograve (PNSACV), costa sudoeste de Portugal. As ervas marinhas Z. noltii, Z. marina e C. nodosa foram recolhidas recorrendo a técnicas de mergulho autónomo, no PNRF. Depois de colhidas as macrófitas foram colocadas numa câmara de crescimento durante quatro dias, com um fotoperíodo de 13:11 dia /noite, para aclimatação às condições de laboratório. A produção de oxigénio foi determinada numa câmara de incubação de 15ml, adaptada a um eléctrodo de oxigénio. A luz foi fornecida por um projector de diapositivos equipado com uma lâmpada de 150W. As diferentes intensidades luminosas foram obtidas através de filtros de densidade neutra. Para cada medição foram utilizados seis segmentos independentes de folhas de cada espécie de erva marinha e seis pontas de talo de cada alga castanha por réplica. Foram efectuados seis réplicas por espécie e por temperatura. A água dentro das câmaras de incubação, foi mantida a uma temperatura constante de 14, 18, 22 ou 26ºC dependendo do tratamento. Para obter curvas fotossintéticas de resposta à luz, foram aplicados em sequência 9 a 11 níveis de luz, desde 0 até 1460 μmol m-2s-1. No final de cada replicado, a luz era desligada para determinação da taxa de respiração no escuro. Para prevenir a saturação no interior das câmaras, a água foi mudada no final de cada nível de luz. A equação de Smith (1936) e Talling (1957) P=Pmax [αI/(Pmax2+(αI)2 )1/2] foi ajustada aos pontos para obtenção do modelo de evolução de produção de oxigénio (curva P-I), onde I é a irradiância (ou PPFD), α é o declive ascendente durante as irradiâncias limitantes e Pmax é a taxa fotossintética máxima. O ponto de meia saturação (Ik) foi obtido dividindo Pmax por α. O software SigmaPlot foi utilizado no ajuste das curvas. De modo a verificar as diferenças entre os parâmetros das curvas, entre as diferentes espécies e temperaturas testadas, foram efectuadas ANOVAs (α = 0,05) utilizando o programa estatístico SigmaStat. O ajuste das curvas P-I de S. muticum foi muito semelhante entre temperaturas, particularmente quando comparadas com as das ervas marinhas, que apresentaram uma muito maior variabilidade entre as temperaturas testadas. A análise dos dados demonstrou que S. muticum é uma espécie euritérmica para a gama de temperatura testada. A 18ºC a alga invasora provou ter um desempenho fotossintético superior quando comparada com a das ervas marinhas. É conhecido através de observações no campo que S. muticum atinge o seu tamanho máximo na iv Primavera. Nessa época do ano a água está em torno dos 18ºC. Com este estudo conclui-se que S. muticum está tão bem adaptado às condições de luz e temperatura do PNRF como as ervas marinhas nativas e que a 18ºC suplanta o seu desempenho. Assim do ponto de vista estritamente fotossintético conclui-se que na Primavera, a alga S. muticum tem a possibilidade de suplantar as ervas marinhas do PNRF, com potencial para se tornar numa invasão. Em relação à alga castanha Cystoseira humilis, a sua resposta à luz foi muito semelhante à de S. muticum. Contudo, a taxa fotossintética bruta, o Pmax e o Ik de C. humilis a 22ºC foi superior à de S. muticum. Concluindo-se que C. humilis está tão bem adaptada como S. muticum a 14, 18 e 26ºC e melhor a 22ºC. Assim do ponto de vista fotossintético C. humilis tem capacidade de competir em vantagem com esta alga invasora. Os dados apresentados neste estudo estão de acordo com as observações feitas no campo uma vez que a invasão no PNSACV está contida a alguns enclaves da zona entre marés. Pode-se concluir que no PNSACV S. muticum não tem uma performance fotossintética que lhe permita suplantar a nativa C. humilis. É recomendado que sejam efectuados outros estudos com aproximações diferentes, como o metabolismo das comunidades, a disponibilidade de substrato, o efeito de sombra e de herbivoria, de modo a fornecer uma explicação mais abrangente sobre a dinâmica desta invasão.
- Complete mitochondrial genome of the branching octocoral Paramuricea grayi (Johnson, 1861), phylogenetic relationships and divergence analysisPublication . Coelho, Márcio; Ledoux, Jean-Baptiste; Boavida, Joana; Paulo, Diogo; Gómez-Gras, Daniel; Bensoussan, Nathaniel; López-Sendino, Paula; Cerrano, Carlo; Kipson, Silvija; Bakran-Petricioli, Tatjana; Garrabou, Joaquim; A, Serrão; Pearson, GarethThe Gray's sea fan, Paramuricea grayi (Johnson, 1861), typically inhabits deep littoral and circalittoral habitats of the eastern temperate and tropical Atlantic Ocean. Along the Iberian Peninsula, where P. grayi is a dominant constituent of circalittoral coral gardens, two segregating lineages (yellow and purple morphotypes) were recently identified using single-copy nuclear orthologues. The mitochondrial genomes of 9 P. grayi individuals covering both color morphotypes were assembled from RNA-seq data, using samples collected at three sites in southern (Sagres and Tavira) and western (Cape Espichel) Portugal. The complete circular mitogenome is 18,668 bp in length, has an A + T-rich base composition (62.5%) and contains the 17 genes typically found in Octocorallia: 14 protein-coding genes (atp6, atp8, cob, cox1-3, mt-mutS, nad1-6, and nad4L), the small and large subunit rRNAs (rns and rnl), and one transfer RNA (trnM). The mitogenomes were nearly identical for all specimens, though we identified a noteworthy polymorphism (two SNPs 9 bp apart) in the mt-mutS of one purple individual that is shared with the sister species P. clavata. The mitogenomes of the two species have a pairwise sequence identity of 99.0%, with nad6 and mt-mutS having the highest rates of non-synonymous substitutions.
- Open coast seagrass restoration. Can we do it? Large scale seagrass transplantsPublication . Paulo, Diogo; Cunha, Alexandra H.; Boavida, Joana; Serrao, Ester; Gonçalves, Emanuel J.; Fonseca, MarkSome of the major challenges in seagrass restoration on exposed open coasts are the choice of transplant design that is optimal for coastlines periodically exposed to high water motion, and understanding the survival and dynamics of the transplanted areas on a long time-scale over many years. To contribute to a better understanding of these challenges, we describe here part of a large-scale seagrass restoration program conducted in a Marine Park in Portugal. The goal of this study was to infer if it was possible to recover seagrass habitat in this region, in order to restore its ecosystem functions. To infer which methods would produce better long term persistence to recover seagrass habitat, three factors were assessed: donor seagrass species, transplant season, source location. Monitoring was done three times a year for 8 years, in which areas and densities of the planted units were measured, to assess survival and growth. The best results were obtained with the species Zostera marina transplanted during spring and summer as compared to Zostera noltii and Cymodocea nodosa. Long-term persistence of established (well rooted) transplants was mainly affected by extreme winter storms but there was evidence of fish grazing effects also. Our results indicate that persistence assessments should be done in the long term, as all transplants were successful (survived and grew initially) in the short term, but were not resistant in the long term after a winter with exceptionally strong storms. The interesting observation that only the largest (11 m(2)) transplanted plot of Z marina persisted over a long time, increasing to 103 m(2) in 8 years, overcoming storms and grazing, raised the hypothesis that for a successful shift to a vegetated state it might be necessary to overpass a minimum critical size or tipping point. This hypothesis was therefore tested with replicates from two donor populations and results showed effects of size and donor population, as only the larger planting units (PUs) from one donor population persisted and expanded. It is recommended that in future habitat restoration efforts large PUs are considered.
- Limited differences in fish and benthic communities and possible cascading effects inside and outside a protected marine area in Sagres (SW Portugal)Publication . Gil Fernandez, C.; Paulo, D.; Serrão, Ester; Engelen, AschwinMarine protected areas (MPAs) are a relatively recent fisheries management and conservation tool for conservation of marine ecosystems and serve as experimental grounds to assess trophic cascade effects in areas were fishing is restricted to some extent. A series of descriptive field studies were performed to assess fish and benthic communities between two areas within a newly established MPA in SW Portugal. We characterized benthic macroalgal composition and determined the size, density and biomass of the main benthic predatory and herbivorous fish species as well as the main benthic herbivorous invertebrates to assess indications of top-down control on the phytobenthic assemblages. Fish species were identical inside and outside the MPA, in both cases Sarpa salpa was the most abundant fish herbivore and Diplodus spp. accounted for the great majority of the benthic predators. However, size and biomass of D. spp. were higher inside than outside the MPA. The main herbivorous invertebrate was the sea urchin Paracentrotus lividus, which was smaller and predominantly showing a crevice-dwelling behaviour in the MPA. In addition, P. lividus size frequency distribution showed a unimodal pattern outside and a bimodal pattern inside the MPA. We found significant differences in the algal assemblages between inside and outside the MPA, with higher abundance of turf and foliose algae inside, and articulated calcareous and corticated macrophytes outside the MPA, but no differences in the invasive Asparagopsis spp. The obtained results show differences in predatory fish and benthic community structure, but not in species richness, inside and outside the MPA. We hypothesize these differences lead to variation in species interactions: directly through predation and indirectly via affecting sea urchins behavioural patterns, predators might drive changes in macroalgal assemblages via trophic cascade in the study area. However due to non-biological differences between the two areas it is difficult to suggest that the MPA causes increased biological parameters of targeted species and to assess predatory control and trophic cascade effects in areas where fishing pressure is reduced. It is therefor advisable to design MPAs so that their impacts can be scientifically evaluated in a proper fashion. (C) 2015 Elsevier Ltd. All rights reserved.
- The rediscovery of Caulerpa prolifera in Ria Formosa, Portugal, 60 years after the previous recordPublication . Cunha, A. H.; E, Varela-Álvarez; Paulo, D. S.; Sousa, Inês; Serrão, EsterThe westernmost occurrence of Caulerpa prolifera on the Atlantic European coast has been accepted in recent decades, to be Huelva province, southern Spain. In April 2011, this species was found in Ria Formosa, southern Portugal, extending its westernmost limit along the Iberian Peninsula coastline. In the course of research into this species it was discovered that this alga had been found in Ria Formosa in the 19th century by the naturalist Welwitsch and subsequently in the 1930s by others but it was never found in the many field studies conducted in Ria Formosa during the past few decades. The species had therefore either become extinct in the area or persisted as a cryptic undetected stage. In order to investigate the source of colonization and to verify the genetic identity, a partial cpDNA region (tufA gene) was sequenced. Comparisons of nucleotide similarity in sequences from the Ria Formosa and from populations of the Atlantic and Mediterranean confirmed the Caulerpa prolifera identification and gave clues about a possible origin of this population as deriving from expansion of a Mediterranean source rather than one from the western Atlantic.
- Recruit survival of Cymodocea nodosa along a depth gradientPublication . Paulo, Diogo; Manent, Pablo; Barrio, Juan M.; Serrão, Ester; Alberto, FilipeClonal plants can reproduce sexually and clonally, expressing different proportions of these different life histories in distinctive environments. In seagrass meadows, light attenuation hinders marine plant colonization in deeper areas of its vertical distribution. Therefore it is expected that the fluorescence maximum quantum yield of seedlings will be higher at deep limits of the meadow relative to shallower depths. We hypothesized that seagrass seedlings experience higher mortality in deeper areas of the meadows than at shallower levels. Our objective was to test survival of seagrass seedlings along a depth gradient in meadows of Cymodocea nodosa in the Canary Islands. Seedlings germinated in laboratory conditions, were transplanted to a natural meadow at three water depths: shallow (5 m), medium (8 m) and deep (12 m). Transplanted seedlings were monitored by measuring maximum quantum yield, leaf length, number of leaves per shoot and survival. Our data suggest that light does not hinder survival of seedlings along the depth gradient of the meadow. Before establishing clonal growth, seedlings in deeper areas had higher survival rates than those in shallow areas. Even though seeds are present at shallow depths and sexual allocation is high, sexual contribution can be lower than expected due to seedling loss.
- A well-kept treasure at depth: precious red coral rediscovered in Atlantic deep coral gardens (SW Portugal) after 300 yearsPublication . Boavida, Joana; Paulo, Diogo; Aurelle, Didier; ARNAUD-HAOND, Sophie; Marschal, Christian; Reed, John; Gonçalves, J. M. S.; Serrão, EsterThe highly valuable red coral Corallium rubrum is listed in several Mediterranean Conventions for species protection and management since the 1980s. Yet, the lack of data about its Atlantic distribution has hindered its protection there. This culminated in the recent discovery of poaching activities harvesting tens of kg of coral per day from deep rocky reefs off SW Portugal. Red coral was irregularly exploited in Portugal between the 1200s and 1700s, until the fishery collapsed. Its occurrence has not been reported for the last 300 years.
- Sexual reproduction vs. clonal propagation in the recovery of a seagrass meadow after an extreme weather eventPublication . Paulo, Diogo; Diekmann, Onno; Ramos, Ana; Alberto, Filipe; Serrao, EsterMarine flowering plants can reproduce sexually and clonally, and the relative contribution of these two modes can be dependent on the environmental conditions. Zostera marina, a seagrass widely distributed in the northern hemisphere, can form annual and perennial meadows with different proportions of sexual versus clonal propagation depending on the environmental disturbance regime. We study the hypothesis that the contribution of sexual propagation varies during the recovery of a seagrass meadow. In this case study, we compare the proportion of sexual versus clonal propagation of a perennial Z. marina meadow before its disappearance due to winter storms and after recovery. Before disturbance, genotypic diversity was high, indicating frequent sexual reproduction events likely to create an abundant seed bank. Seedling germination allowed the population to recover after the extreme disturbance. As months passed, seedlings became rare and finally absent, giving place to adult shoots. In an advanced stage of colonization, the shoots colonized the area by vegetative growth, which lowered the genotypic diversity. Despite this reduction over time, the genotypic diversity of the new meadow is still high, demonstrating the importance of sexual reproduction in meadow recovery and persistence.
- First description of seagrass distribution and abundance in Sao Tome and PrincipePublication . Alexandre, Ana; Silva, João; Ferreira, Rogério; Paulo, Diogo; Serrao, Ester; Santos, RuiSeagrass meadows in Sao Tome and Principe, eastern Atlantic Ocean, are described here for the first time. Specifically, we quantified the biomass and density of seagrasses, characterized the plant morphology and measure their nutrient content as a proxy of the nutrient environmental conditions where the meadows develop. The seagrass Halodule wrightii was found in two locations of the northeastern coast of the island of Sao Tome: 1) developing throughout an estimated area of 1500 ha surrounding Cabras islet, at a depth range of 4-10 m, on sandy bottom; and 2) at Santana bay with an area of 1500 m(2) at 5-10 m depth, on sandy bottom. A highly morphologically different population of Halodule wrightii was found on the northeastern coast of the island of Principe, off Abade beach, covering an area of 135 m2 at 4 m depth. Further research is needed to assess if this is a different species. Shoot biomass and density was 10 and 4-fold higher in Sao Tome than in Principe, respectively. CN ratios of above and belowground tissues of plants collected in Sao Tome were also significantly higher than in Principe. The carbon content of Halodule leaves from Sao Tome and Principe (41%) was much higher than that reported for other Halodule species, suggesting that meadows may have an important ecological role for carbon fixation. The presence of H. wrightii in Sao Tome and Principe raises ecological and evolutionary questions that warrant further research.
- Less is more: seagrass restoration success using less vegetation per areaPublication . Mourato, Carolina; Padrão, Nuno; Serrao, Ester A.; Paulo, DiogoSeagrass restoration in open coast environments presents unique challenges. Traditional sod transplant designs, though relatively successful in these environments, are impractical for large-scale restoration due to high biomass requirements. Here, we develop the checkers design, which aims to optimise the usage of biomass by transplanting fewer sods in a checkerboard pattern. We established six plots (9 m2 each) for each species (Zostera marina and Zostera noltei), with 25 sods in each plot. The area, percent cover, density, and leaf length were measured at 1, 6, and 12 months. The plots located on the seaward end of the transplant design vanished over the winter, suggesting location-dependent survival influenced by winter storms. Nevertheless, both species exhibited increased percentages of cover, density, and vegetated area after one year, with variations between species. Z. noltei showed a slower expansion but greater resilience to winter, while Z. marina displayed a higher density and cover over the first 6 months but experienced area loss during the winter. Despite these differences, both species survived and increased vegetated areas after one year, indicating the viability and promise of the checkers method for large-scale restoration. However, careful consideration of location or storm-mitigating measures is essential for the successful implementation of this method.