Susana Cabaço | Independent Researcher (original) (raw)
Papers by Susana Cabaço
Marine Ecology Progress Series, 2005
We used population reconstruction techniques to assess for the first time the population dynamics... more We used population reconstruction techniques to assess for the first time the population dynamics of a seagrass, Cymodocea nodosa, exposed to long-term elevated CO2 near three volcanic seeps and compare them with reference sites away from the seeps. Under high CO2, the density of shoots and of individuals (apical shoots), and the vertical and horizontal elongation and production rates, were higher. Nitrogen effects on rhizome elongation and production rates and on biomass, were stronger than CO2 as these were highest at the location where the availability of nitrogen was highest. At the seep where the availability of CO2 was highest and nitrogen lowest, density of shoots and individuals were highest, probably due to CO2 effects on shoot differentiation and induced reproductive output, respectively. In all three seeps there was higher short- and long-term recruitment and growth rates around zero, indicating that elevated CO2 increases the turnover of C. nodosa shoots.
Cahiers De Biologie Marine, 2014
Marine Pollution Bulletin, 2013
The aim of this study was to develop an ecological quality index based on the seagrass Zostera no... more The aim of this study was to develop an ecological quality index based on the seagrass Zostera noltii (ZoNI) according to the WFD requirements. Eleven Z. noltii meadows of SW Iberian Peninsula under contrasting levels of anthropogenic disturbance were considered: 5 sites in Ria Formosa (Portugal), and 6 sites in Spain (Huelva and Cadiz). Environmental quality was assessed through nutrients of the water column and seagrass variables from different organization levels; those variables were analyzed using PCA (47% of explained variance on the first component) to calculate the ecological quality ratio (that was significantly correlated to the environmental variables, R(2)=0.51, p<0.01) and the ecological quality status of the sites. As a result, 4 sites were classified as good, 6 sites as moderate and 3 sites as poor ecological status. The developed index ZoNI showed to be suitable to assess the ecological status of estuarine and coastal systems in SW Iberian Peninsula reflecting their water quality.
Ecological Indicators, 2012
Seagrasses are clonal plants sharing a similar architecture and presenting a highly organised gro... more Seagrasses are clonal plants sharing a similar architecture and presenting a highly organised growth. Seagrass growth relies on the reiteration of ramets, which are composed of modules (ie leaves, piece of rhizome, roots, flowers or inflorescences). The understanding of the ...
ABSTRACT the survival, growth and production of the seagrass Zostera noltii were assessed in thre... more ABSTRACT the survival, growth and production of the seagrass Zostera noltii were assessed in three different culture media (sand, agar and seawater). Plants composed of 3 modules were placed in acrylic containers (n = 24 per treatment) and assigned into 3 replicate aquaria, kept in a growth chamber. Plant survival and growth were determined after 30 days and at the end of the experiment (60 days). Plant survival was high (> 80%) for the three culture media tested, during the experimental period. no significant differences were found in shoot production, internode production or rhizome elongation rates among the different culture media, even though all parameters decreased significantly with time. Plants in agar and sediment media (81% and 83%, respectively) showed higher branching during the first 30 days of experiment than plants cultured only in seawater (67%), but no significant differences were detected. no significant effects of the culture media or incubation time were found for the elongation of branches, and branch internode produc-tion. However, branch production rate decreased significantly with time. these results showed that a simple seawater medium can be used in laboratory microcosm experiments, particularly for short-term experiments (up to 30 days). Introduction Zostera noltii is a small seagrass species occurring along the intertidal and subtidal areas of estuaries and shallow coastal lagoons, from northern Europe to north-west Africa, and in the Mediterranean Sea (den hartog, 1970). its small size represents a big challenge for plant-specific fieldwork, especially in studies, which require a meticulous handling of the plants. Particular technical hitches arise when there is the need for tagging individual plants in the field, since rhi-zomes are too fragile to be tagged, often being broken or damaged. the difficulty in using tagging techniques limits the investigation of the demographic param-eters of this species such as growth, mortality and recruitment. Moreover, the dense and delicate system of rhizomes and roots within the muddy sediments, which frequently characterize Zostera noltii meadows, constitutes another major drawback while assessing the plant's belowground fraction. however, unlike many other seagrasses, its small size represents an enormous advantage for laboratory microcosm experiments, especially in terms of lab space facilities. Preparing culture media for laboratory microcosm experiments involves, most of the time, vast logistic and great human effort, such as bringing natural sedi-ments to the laboratory. A simple alternative is to grow the plants in seawater, but this does not seem quite representative of natural conditions, as seagrasses are rooted plants. this study aimed to assess the survival, growth and production of Zostera noltii plants in three different culture media, namely natural sediment, agar and seawater. leaf chlorophyll content was determined as a physiological indicator of the plant's condition.
Journal of Ecology, 2013
1. The available data from experimental and descriptive studies on seagrass biomass and density r... more 1. The available data from experimental and descriptive studies on seagrass biomass and density responses to nutrient enrichment was analysed to assess the intraspecific mechanisms operating within seagrass populations and if biomass-density relationships can provide relevant metrics for monitoring seagrasses. 2. The response of shoot biomass and density to nutrient enrichment was dependent on the type of study; the short-term positive response of biomass and density in experimental studies reveals context-specific nutrient limitation of seagrasses. The long-term negative response of descriptive studies probably results from ecosystem-scale events related to nutrient enrichment such as increased turbidity, algal blooms, epiphyte loads and anoxia. 3. Most seagrass species analysed lie in the non-thinning part of the theoretical biomass-density curves. A simultaneous increase of biomass and decrease of density, evidence of self-thinning, was only observed in 4 out of 28 studies. The a...
Marine Ecology Progress Series, 2005
We used population reconstruction techniques to assess for the first time the population dynamics... more We used population reconstruction techniques to assess for the first time the population dynamics of a seagrass, Cymodocea nodosa, exposed to long-term elevated CO2 near three volcanic seeps and compare them with reference sites away from the seeps. Under high CO2, the density of shoots and of individuals (apical shoots), and the vertical and horizontal elongation and production rates, were higher. Nitrogen effects on rhizome elongation and production rates and on biomass, were stronger than CO2 as these were highest at the location where the availability of nitrogen was highest. At the seep where the availability of CO2 was highest and nitrogen lowest, density of shoots and individuals were highest, probably due to CO2 effects on shoot differentiation and induced reproductive output, respectively. In all three seeps there was higher short- and long-term recruitment and growth rates around zero, indicating that elevated CO2 increases the turnover of C. nodosa shoots.
Cahiers De Biologie Marine, 2014
Marine Pollution Bulletin, 2013
The aim of this study was to develop an ecological quality index based on the seagrass Zostera no... more The aim of this study was to develop an ecological quality index based on the seagrass Zostera noltii (ZoNI) according to the WFD requirements. Eleven Z. noltii meadows of SW Iberian Peninsula under contrasting levels of anthropogenic disturbance were considered: 5 sites in Ria Formosa (Portugal), and 6 sites in Spain (Huelva and Cadiz). Environmental quality was assessed through nutrients of the water column and seagrass variables from different organization levels; those variables were analyzed using PCA (47% of explained variance on the first component) to calculate the ecological quality ratio (that was significantly correlated to the environmental variables, R(2)=0.51, p<0.01) and the ecological quality status of the sites. As a result, 4 sites were classified as good, 6 sites as moderate and 3 sites as poor ecological status. The developed index ZoNI showed to be suitable to assess the ecological status of estuarine and coastal systems in SW Iberian Peninsula reflecting their water quality.
Ecological Indicators, 2012
Seagrasses are clonal plants sharing a similar architecture and presenting a highly organised gro... more Seagrasses are clonal plants sharing a similar architecture and presenting a highly organised growth. Seagrass growth relies on the reiteration of ramets, which are composed of modules (ie leaves, piece of rhizome, roots, flowers or inflorescences). The understanding of the ...
ABSTRACT the survival, growth and production of the seagrass Zostera noltii were assessed in thre... more ABSTRACT the survival, growth and production of the seagrass Zostera noltii were assessed in three different culture media (sand, agar and seawater). Plants composed of 3 modules were placed in acrylic containers (n = 24 per treatment) and assigned into 3 replicate aquaria, kept in a growth chamber. Plant survival and growth were determined after 30 days and at the end of the experiment (60 days). Plant survival was high (> 80%) for the three culture media tested, during the experimental period. no significant differences were found in shoot production, internode production or rhizome elongation rates among the different culture media, even though all parameters decreased significantly with time. Plants in agar and sediment media (81% and 83%, respectively) showed higher branching during the first 30 days of experiment than plants cultured only in seawater (67%), but no significant differences were detected. no significant effects of the culture media or incubation time were found for the elongation of branches, and branch internode produc-tion. However, branch production rate decreased significantly with time. these results showed that a simple seawater medium can be used in laboratory microcosm experiments, particularly for short-term experiments (up to 30 days). Introduction Zostera noltii is a small seagrass species occurring along the intertidal and subtidal areas of estuaries and shallow coastal lagoons, from northern Europe to north-west Africa, and in the Mediterranean Sea (den hartog, 1970). its small size represents a big challenge for plant-specific fieldwork, especially in studies, which require a meticulous handling of the plants. Particular technical hitches arise when there is the need for tagging individual plants in the field, since rhi-zomes are too fragile to be tagged, often being broken or damaged. the difficulty in using tagging techniques limits the investigation of the demographic param-eters of this species such as growth, mortality and recruitment. Moreover, the dense and delicate system of rhizomes and roots within the muddy sediments, which frequently characterize Zostera noltii meadows, constitutes another major drawback while assessing the plant's belowground fraction. however, unlike many other seagrasses, its small size represents an enormous advantage for laboratory microcosm experiments, especially in terms of lab space facilities. Preparing culture media for laboratory microcosm experiments involves, most of the time, vast logistic and great human effort, such as bringing natural sedi-ments to the laboratory. A simple alternative is to grow the plants in seawater, but this does not seem quite representative of natural conditions, as seagrasses are rooted plants. this study aimed to assess the survival, growth and production of Zostera noltii plants in three different culture media, namely natural sediment, agar and seawater. leaf chlorophyll content was determined as a physiological indicator of the plant's condition.
Journal of Ecology, 2013
1. The available data from experimental and descriptive studies on seagrass biomass and density r... more 1. The available data from experimental and descriptive studies on seagrass biomass and density responses to nutrient enrichment was analysed to assess the intraspecific mechanisms operating within seagrass populations and if biomass-density relationships can provide relevant metrics for monitoring seagrasses. 2. The response of shoot biomass and density to nutrient enrichment was dependent on the type of study; the short-term positive response of biomass and density in experimental studies reveals context-specific nutrient limitation of seagrasses. The long-term negative response of descriptive studies probably results from ecosystem-scale events related to nutrient enrichment such as increased turbidity, algal blooms, epiphyte loads and anoxia. 3. Most seagrass species analysed lie in the non-thinning part of the theoretical biomass-density curves. A simultaneous increase of biomass and decrease of density, evidence of self-thinning, was only observed in 4 out of 28 studies. The a...