The relationship between phytoplankton diversity and community function in a coastal lagoon

The decrease of biodiversity related to the phenomena of global climate change is stimulating the scientific community towards a better understanding of the relationships between biodiversity and ecosystem functioning. In ecosystems where marked biodiversity changes occur at seasonal time scales, it is easier to relate them with ecosystem functioning. The objective of this work is to analyse the relationship between phytoplankton diversity and primary production in St. André coastal lagoon – SW Portugal. This lagoon is artificially opened to the sea every year in early spring, exhibiting a shift from a marine dominated to a low salinity ecosystem in winter. Data on salinity, temperature, nutrients, phytoplankton species composition, chlorophyll a (Chl a) concentration and primary production were analysed over a year. Modelling studies based on production-irradiance curves were also conducted. A total of 19 taxa were identified among diatoms, dinoflagellates and euglenophyceans, the less abundant group. Lowest diversities (Shannon– Wiener index) were observed just before the opening to the sea. Results show a negative correlation (p<0.05) between diversity and chlorophyll a (Chl a) concentration (0.2–40.3 mg Chl a m-3). Higher Chl a values corresponded to periods when the community was dominated by the dinoflagellate Prorocentrum minimum (>90% of cell abundance) and production was maximal (up to 234.8 mg C m-3 h-1). Maximal photosynthetic rates (Pmax) (2.0–22.5 mg C mg Chl a-1 h-1) were higher under lower Chl a concentrations. The results of this work suggest that decreases in diversity are associated with increases in biomass and production, whereas increases correspond to opposite trends. It is suggested that these trends, contrary to those observed in terrestrial and in some benthic ecosystems, may be a result of low habitat diversity in the water column and resulting competitive pressure. The occurrence of the highest photosynthetic rates when Chl a is low, under some of the highest diversities, suggests a more efficient use of irradiance under low biomass–high diversity conditions. Results suggest that this increased efficiency is not explained by potential reductions in nutrient limitation and intraspecific competition under lower biomasses and may be a result of niche complementarity

Grandes branquiópodes dulçaquícolas em Portugal: actualização da sua distribuição

This study is based largely on 20 years of field and laboratory work, with surveys conducted by the authors and some other researchers. During this period several studies dealing with freshwater large branchiopods (FLB) were carried out, resulting in scientific publications and project reports. The distribution of FLB in Portugal was presented in 2 international scientific meetings, but apart from a first paper by Vianna-Fernandes in 1951 and an update done by ourselves in 1999 concerning the southwest Portugal, no other information has been published. Therefore, this work intends to bring up to date the known distribution of this faunal group in freshwater temporary systems. This is pertinent because of the recent revision of the taxon Triops cancriformis on the basis of genetic analyses. The Portuguese populations were assigned either to the Portuguese endemism T. vicentinus, or to T. baeticus, the more widely spread Iberian species, both belonging to the T. mauritanicus complex. Furthermore, a new species, Tanymastigites lusitanica was found and described in Portugal. More recently, a male free (or, at least, a strongly female-biased) metapopulation of T cancriformis was discovered in a rice field in the central region of Portugal. Here we present an updated status of FLB species of Portuguese temporary lentic systems and their distribution, plotted on a UTM (10 x 10 km) grid. A total of 505 sites (temporary ponds or assemblages of closely located, not individual temporary pools) have been surveyed (455 by us). In 241 of these (47.7%) at least one species of FLB was found on at least one occasion. Of the 505 sites, only 87 are located north of the Tagus River and of these, at least one species was found in only 17 (19.5%). South of the Tagus River (Alentejo and Algarve), 53.6% of the sites were inhabited by at least one species. This list comprises 7 anostracans, 2 spinicaudatans and 4 notostracans, including 3 species endemic to the Iberian Peninsula and another 3 to Portugal.O presente trabalho é, maioritariamente, o resultado de 20 anos de trabalho de campo e de laboratório, com campanhas realizadas pelos autores e por outros investigadores. Durante este período foram realizados vários estudos de que resultaram diversas publicações e relatórios de projectos. O conhecimento da distribuição dos grandes branquiópodes dulçaquícolas (GBD) em Portugal baseia-se num primeiro artigo de 1951 de Vianna-Fernandes e de uma actualização do conhecimento publicada por nós em 1999 e relativa ao sudoeste de Portugal. A sua actualização foi posteriormente apresentada em dois encontros científicos internacionais, mas nunca foi publicada. Assim, este trabalho pretende actualizar o conhecimento sobre a distribuição, em Portugal, deste grupo faunístico de sistemas lênticos temporários. Esta intenção é pertinente, visto que, na última década, o taxon Triops cancriformis foi revisto com base em análises genéticas. As populações portuguesasforam atribuídas quer ao endemismo português T. vicentinus, quer a T. baeticus, a espécie com distribuição mais alargada na península ibérica, ambas anteriormente incluídas no complexo T. mauritanicus. Além destas, uma nova espécie, Tanymastigites lusitanica foi descoberta e descrita em Portugal. Mais recentemente, foi encontrada num campo de cultivo de arroz na região central de Portugal, uma metapopulação de T. cancriformis aparentemente composta unicamente por fêmeas. Apresenta-se neste trabalho o estado actual do conhecimento sobre a distribuição dos GBD de sistemas lênticos temporários portugueses, em mapas de quadrícula UTM (10 × 10 km). Foram prospectados um total de 505 sítios (charcos temporários ou conjuntos de charcos com localização próxima, não individualizável), 455 pelos autores. Em 241 deles (47.7%) foi observada a presença de pelo menos uma espécie de GBD numa ocasião. Dos 505 sítios, apenas 87 estão localizados a Norte do rio Tejo, e nestes apenas em 17 (19.5%) foi detectada a presença de pelo menos 1 espécie de GBD. A sul do rio Tejo (Alentejo e Algarve), em 53.6% dos sítios foi encontrada pelo menos uma espécie de GBD. Esta lista inclui 13 espécies (7 Anostraca, 2 Spinicaudata e 4 Notostraca), entre as quais 3 endemismos ibéricos e outros 3 endemismos portugueses.FCT - Foundation for Science and Technology [UID/Multi/04326/2013, UID/MAR/04292/2013]LIFE + Nature Project "Conservacao de charcos temporarios na costa Sudoeste de Portugal""Estudo da Ecologia das Lagoas Temporarias do Sudoeste de Portugal"-Protocolo de colaboracao CCMAR-PNSACV, ICN funding"Identificacao dos Elementos de Conservacao (Fauna de Crustaceos Filopodes e Anfibios) nos Char cos temporarios do Parque Natural do Vale do Guadiana e Areas limitrofes"-Protocolo de colaboracao CCMAR-ICN, ICN funding"Estudo dos Grandes Branquiopodes das Lagoas Temporarias na area de influencia dos Parques Naturais do Tejo Internacional e da Serra de Aires e Candeeiros"PNTIPNSAC chiefdomsConsorcio BIO3 / Matos, Fonseca & Associados, Estudos e Projector, Lda-"Plano de Conservacao para os Charcos Temporarios Mediterranicos na regido de implementacao do EFMA", EDIA fundinginfo:eu-repo/semantics/publishedVersio

The relationship between phytoplankton diversity and community function in a coastal lagoon

The decrease of biodiversity related to the phenomena of global climate change is stimulating the scientific community towards a better understanding of the relationships between biodiversity and ecosystem functioning. In ecosystems where marked biodiversity changes occur at seasonal time scales, it is easier to relate them with ecosystem functioning. The objective of this work is to analyse the relationship between phytoplankton diversity and primary production in St. André coastal lagoon – SW Portugal. This lagoon is artificially opened to the sea every year in early spring, exhibiting a shift from a marine dominated to a low salinity ecosystem in winter. Data on salinity, temperature, nutrients, phytoplankton species composition, chlorophyll a (Chl a) concentration and primary production were analysed over a year. Modelling studies based on production-irradiance curves were also conducted. A total of 19 taxa were identified among diatoms, dinoflagellates and euglenophyceans, the less abundant group. Lowest diversities (Shannon– Wiener index) were observed just before the opening to the sea. Results show a negative correlation (p<0.05) between diversity and chlorophyll a (Chl a) concentration (0.2–40.3 mg Chl a m-3). Higher Chl a values corresponded to periods when the community was dominated by the dinoflagellate Prorocentrum minimum (>90% of cell abundance) and production was maximal (up to 234.8 mg C m-3 h-1). Maximal photosynthetic rates (Pmax) (2.0–22.5 mg C mg Chl a-1 h-1) were higher under lower Chl a concentrations. The results of this work suggest that decreases in diversity are associated with increases in biomass and production, whereas increases correspond to opposite trends. It is suggested that these trends, contrary to those observed in terrestrial and in some benthic ecosystems, may be a result of low habitat diversity in the water column and resulting competitive pressure. The occurrence of the highest photosynthetic rates when Chl a is low, under some of the highest diversities, suggests a more efficient use of irradiance under low biomass–high diversity conditions. Results suggest that this increased efficiency is not explained by potential reductions in nutrient limitation and intraspecific competition under lower biomasses and may be a result of niche complementarity

Acerca de falas da terra. Ecologia e tradição

O projecto Falas da Terra - Ecologia e Tradição surgiu quando à disciplina de Literatura Tradicional Oral apeteceu o transborde: a detecção de paradigmas ambientais, a descrição da fisionomia da terra. • quer enquanto solo arável: terra, corpo feminino lavrado e semeado pelo corpo masculino (o arado e a semente) ou terra tal como a quadra seguinte reiteradamente a refere: Eu sou devedor à terra A terra me está devendo A terra me paga em vida E eu pago à terra em morrendo.* Também o órgão por excelência do ser humano (porque garantia do amor e, por isso, da vida), o coração, é, no Cancioneiro, apresentado como herdade, coutada, terra literalmente cavada para semear saudades, sempre com o objectivo alfaiar - ou não fosse o lugar da fala o lugar do encontro, do diálogo: O meu coração é terra Hei-de mandá-lo cavar Para semear saudades Que tenho de te falar

Evaluation of ammonium and phosphate release from intertidal and subtidal sediments of a shallow coastal lagoon (Ria Formosa – Portugal): a modelling approach

During an annual cycle, overlying water and sediment cores were collected simultaneously at three sites (Tavira, Culatra and Ramalhete) of Ria Formosa’s intertidal muddy and subtidal sandy sediments to determine ammonium, nitrates plus nitrites and phosphate. Organic carbon, nitrogen and phosphorus were also determined in superficial sediments. Ammonium and phosphate dissolved in porewater were positively correlated with temperature (P < 0.01) in muddy and sandy sediments, while the nitrogen-oxidized forms had a negative correlation (P < 0.02) in muddy sediments probably because mineralization and nitrification/denitrification processes vary seasonally. Porewater ammonium profiles evidenced apeak in the top-most muddy sediment (380 lM) suggesting higher mineralization rate when oxygen is more available, while maximum phosphate concentration (113 lM) occurred in the sub-oxic layer probably due to phosphorus desorption under reduced conditions. In organically poor subtidal sandy sediments, nutrient porewater concentrations were always lower than in intertidal muddy sediments, ranging annually from 20 lMto 100 lM for ammonium and from 0.05 lM to 16 lM for phosphate. Nutrient diffusive fluxes predicted by a mathematical model were higher during summer, inbothmuddy (104 nmol cm–2d–1––NH4+; 8 nmol cm–2 d–1––HPO4–2) and sandy sediments (26 nmol cm–2 d–1––NH4+; 1 nmol cm–2 d–1––HPO4–2), while during lower temperature periods these fluxes were 3–4 times lower. Based on simulated nutrient effluxes, the estimated annual amount of ammonium and phosphate exported from intertidal areas was three times higher than that released from subtidal areas (22 ton year–1––NH4+; 2 ton year–1––HPO4–2), emphasizing the importance of tidal flats to maintain the high productivity of the lagoon. Global warming scenarios simulated with the model, revealed that an increase in lagoon water temperature only produces significant variations (P < 0.05) for NH4+ in porewater and consequent diffusive fluxes, what will probably affect the system productivity due to a N/P ratio unbalance

Evaluation of ammonium and phosphate release from intertidal and subtidal sediments of a shallow coastal lagoon (Ria Formosa – Portugal): a modelling approach

During an annual cycle, overlying water and sediment cores were collected simultaneously at three sites (Tavira, Culatra and Ramalhete) of Ria Formosa’s intertidal muddy and subtidal sandy sediments to determine ammonium, nitrates plus nitrites and phosphate. Organic carbon, nitrogen and phosphorus were also determined in superficial sediments. Ammonium and phosphate dissolved in porewater were positively correlated with temperature (P < 0.01) in muddy and sandy sediments, while the nitrogen-oxidized forms had a negative correlation (P < 0.02) in muddy sediments probably because mineralization and nitrification/denitrification processes vary seasonally. Porewater ammonium profiles evidenced apeak in the top-most muddy sediment (380 lM) suggesting higher mineralization rate when oxygen is more available, while maximum phosphate concentration (113 lM) occurred in the sub-oxic layer probably due to phosphorus desorption under reduced conditions. In organically poor subtidal sandy sediments, nutrient porewater concentrations were always lower than in intertidal muddy sediments, ranging annually from 20 lMto 100 lM for ammonium and from 0.05 lM to 16 lM for phosphate. Nutrient diffusive fluxes predicted by a mathematical model were higher during summer, inbothmuddy (104 nmol cm–2d–1––NH4+; 8 nmol cm–2 d–1––HPO4–2) and sandy sediments (26 nmol cm–2 d–1––NH4+; 1 nmol cm–2 d–1––HPO4–2), while during lower temperature periods these fluxes were 3–4 times lower. Based on simulated nutrient effluxes, the estimated annual amount of ammonium and phosphate exported from intertidal areas was three times higher than that released from subtidal areas (22 ton year–1––NH4+; 2 ton year–1––HPO4–2), emphasizing the importance of tidal flats to maintain the high productivity of the lagoon. Global warming scenarios simulated with the model, revealed that an increase in lagoon water temperature only produces significant variations (P < 0.05) for NH4+ in porewater and consequent diffusive fluxes, what will probably affect the system productivity due to a N/P ratio unbalance

Analysis of coastal lagoon metabolism as a basis for management

This work was carried out in a shallow eutrophic coastal lagoon (St. André lagoon, SW Portugal) which is artificially opened to the sea each year in early spring. Macrophytes, mainly Ruppia cirrhosa, are keystone species in this ecosystem covering up to 60% of its total area with peak biomasses over 500 g DWm−2. The main objectives were to study ecosystem metabolism, to evaluate the metabolic contribution to the community of the macrophyte stands and their influence in the development of thermal stratification and bottom oxygen depletion. The work combined an experimental and a modelling methodology. The experimental approach included open water, mesocosm and microcosm seasonal experiments. During these experiments several physical, chemical and biological parameters were monitored in the lagoon and in plastic enclosures (mesocosms) for periods of 24 hours. The microcosm experiments followed the light-dark bottle technique. The simultaneous use of these different methodologies allowed the analysis of the contribution of the planktonic and benthic compartments to the ecosystem’s oxygen budget. The modelling work was based on the mathematical simulation of heat and gas exchanges in a vertically resolved water column, under different macrophyte densities. Several simulations were carried out, in order to investigate the importance of the macrophytes in the development of water column stratification and anoxia. The simulation results suggest that macrophytes may greatly influence thermocline and oxycline development. This influence is proportional to their biomass and canopy height. It is suggested that controlled macrophyte biomass removal of up to 25% of available biomass in summer, may be useful in preventing bottom anoxia without compromising benthic net primary production

Estimation of secondary production of the Faro/ Ancão artificial reefs

The secondary productivity of reef epifauna is one of the least investigated aspects in artificial reef research. During the first 12 months after the deployment of the Faro/Ancao (Algarve, Portugal) artificial reef, we assessed the effect of substratum orientation on the secondary production of epibenthos, using the Boysen-Jensen method. Whenever the method could not be applied, secondary production was estimated by the P/B ratio. The results showed that the epibenthic production was higher on the horizontal surface throughout the study. However, at the end of the study period, the mean production showed similar values. The horizontally oriented surfaces showed a mean production between 128 and 103 g m-2 yr-1, while at the vertical surfaces the mean production varied between 103 and 98 g m-2 yr-1. Furthermore, the mean annual production was extrapolated for all the Algarve artificial reef complex, and we concluded that after one year of deployment theses artificial reefs were able to generate around 5 MT of epibenthic fauna

Analysis of coastal lagoon metabolism as a basis for management

This work was carried out in a shallow eutrophic coastal lagoon (St. André lagoon, SW Portugal) which is artificially opened to the sea each year in early spring. Macrophytes, mainly Ruppia cirrhosa, are keystone species in this ecosystem covering up to 60% of its total area with peak biomasses over 500 g DWm−2. The main objectives were to study ecosystem metabolism, to evaluate the metabolic contribution to the community of the macrophyte stands and their influence in the development of thermal stratification and bottom oxygen depletion. The work combined an experimental and a modelling methodology. The experimental approach included open water, mesocosm and microcosm seasonal experiments. During these experiments several physical, chemical and biological parameters were monitored in the lagoon and in plastic enclosures (mesocosms) for periods of 24 hours. The microcosm experiments followed the light-dark bottle technique. The simultaneous use of these different methodologies allowed the analysis of the contribution of the planktonic and benthic compartments to the ecosystem’s oxygen budget. The modelling work was based on the mathematical simulation of heat and gas exchanges in a vertically resolved water column, under different macrophyte densities. Several simulations were carried out, in order to investigate the importance of the macrophytes in the development of water column stratification and anoxia. The simulation results suggest that macrophytes may greatly influence thermocline and oxycline development. This influence is proportional to their biomass and canopy height. It is suggested that controlled macrophyte biomass removal of up to 25% of available biomass in summer, may be useful in preventing bottom anoxia without compromising benthic net primary production

Feeding ecology of Nereis diversicolor (O.F. Müller) (Annelida, Polychaeta) on estuarine and lagoon environments in the southwest coast of Portugal

A ecologia alimentar de Nereis diversicolor (O.F. Müller, 1776) (Annelida: Polychaeta) foi estudada num período de 14 meses em três sistemas estuarino-lagunares da costa Sudoeste de Portugal (Odeceixe, Aljezur e Carrapateira). A análise do conteúdo digestivo revelou uma variação da dieta de acordo com os locais estudados, época do ano e com o tamanho dos indivíduos. Não houve diferenças nos conteúdos de machos e fêmeas. Foram encontrados em todas as estações amostradas um total de trinta itens, mas apenas cinco revelaram uma ocorrência superior à 1%. Estes foram: muco (56.3%), areia (17.6%), detritos vegetais (10.7%), Nereididae (7.7%) e Corophium sp. (1.8%). N. diversicolor evidenciou hábitos filtradores, em todas as estações amostradas embora na Carrapateira tenham sido detectadas percentagens de carnivoría ligeiramente superiores às encontradas em Odeceixe e Aljezur. O principal conteúdo do tracto digestivo foi o muco (complexo alimentar que aglutina matéria orgânica, bactérias, fungos e fitoplâncton). ------ ABSTRACT ------ The feeding ecology of Nereis diversicolor (O. F. Müller, 1776) (Annelida: Polychaeta) was studied over 14 months at three estuarine-lagoon systems of the Southwest coast of Portugal (Odeceixe, Aljezur and Carrapateira). The analyses of digestive tract revealed that diet change according to site, period of the year and individual sizes. There are no differences in the digestive contents between sexes. In all sampling stations a total of thirty items were found, but only five shown an occurrence superior to 1%. These were: mucus (56.3%), sand (17.6%), vegetable detritus (10.7%), Nereididae (7.7%) and Corophium sp. (1.8%). N. diversicolor was detected in all sampling stations with a filter-feeding behaviour, although in Carrapateira there is evidence of slightly higher carnivore behaviour than in Odeceixe and Aljezur. Mucus (a food complex including organic matter, bacteria, fungi and phytoplankton) was the main gut content