Fiona Tomas - Academia.edu (original) (raw)
Papers by Fiona Tomas
Aquaculture Environment Interactions, Dec 3, 2020
Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which in... more Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as 'essential fish habitat', restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.
OCEANS 2021: San Diego – Porto, Sep 20, 2021
This paper describes a new methodology to monitor and assess marine sites of special ecological i... more This paper describes a new methodology to monitor and assess marine sites of special ecological interests, such as, those ecosystems formed by the meadows of Posidonia oceanica. This new procedure includes the use of Autonomous Marine Vehicles (AMV), image processing techniques and Convolutional Neural Networks (CNN) to explore extensive areas colonized with this seagrass, form 2D and 3D maps, and quantity, automatically, the bottom coverage of this species. This new approach starts a new paradigm in the task of qualifying and quantifying the state of certain benthic marine habitats since, compared with traditional and current methods performed by divers, ours decreases costs, infrastructures and personal security measures, and increases the mission time, the size of the covered areas, the amount and quality of gathered data and the accuracy in its later processing.
Phytochemistry, Apr 1, 2022
Differences in phenolic composition across different ontogenic stages can be crucial in determini... more Differences in phenolic composition across different ontogenic stages can be crucial in determining the interaction outcomes between plants and their surrounding biotic environment. In seagrasses, specific phenolic compounds have rarely been analyzed and remain unexplored in ontogenic stages other than non-reproductive adults. Furthermore, it is generally accepted that plants would prioritize defense (e.g., through increased phenolic content) on tissues or stages that are critical for plant fitness but how this affects nutritional quality or plant resources has been scarcely explored. We analyzed how phenolic composition, N and C content and carbohydrate resources varied among different life stages (i.e. old and young leaves of reproductive and non-reproductive plants, and leaves of seedlings) in the seagrass Posidonia oceanica. We identified five phenolic compounds, whose structures were established as hydroxycinnamate esters of tartaric acid. Also, our results show that in all examined ontogenic stages phenolic compounds have the same qualitative composition but inflorescences exhibit higher contents than vegetative tissues. We did not find a reduction in stored resources in reproductive plants, pointing to some kind of compensatory mechanism in the production or storage of resources. In contrast, seedlings seemed to have less phenolic compounds than reproductive plants, perhaps due to limited resources available to allocate to phenolic production. Our results demonstrate how different ontogenic stages change their investment in specialized phenolic compounds prioritizing different functions according to the needs and limitations of that stage.
Marine Pollution Bulletin, Sep 1, 2018
Seedlings are a key life stage in seagrasses, providing genetic diversity and being a useful tool... more Seedlings are a key life stage in seagrasses, providing genetic diversity and being a useful tool for restoration. We examined the influence of increased sediment nutrients and the presence of the invasive macroalga Caulerpa cylindracea on the success of in situ transplanting Posidonia oceanica seedlings in a six-month experiment. Our results indicate that one-year old seedlings successfully survive in the field and their survival and growth are positively affected by the presence of C. cylindracea. Furthermore, nutrient addition in the sediment had positive effects on both C. cylindracea (increasing its cover) and seedlings (increasing leaf development), and the increased C. cylindracea cover did not result in detrimental effects on seedlings. Therefore, biological invasions and nutrient addition do not reinforce each other in the short term to negatively impact transplanted seedlings, which highlights facilitative interactions between invasive algae and native seagrass and provides useful information for successful strategies of seagrass restoration.
Trabajo presentado en la Western Society of Naturalists Meeting, celebrada en San Diego, Californ... more Trabajo presentado en la Western Society of Naturalists Meeting, celebrada en San Diego, California, Estados Unidos, del 11 al 14 de noviembre de 2010
Scientific Reports, Dec 1, 2016
Under future increased CO 2 concentrations, seagrasses are predicted to perform better as a resul... more Under future increased CO 2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO 2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO 2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO 2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed.
Marine Pollution Bulletin, Apr 1, 2019
Science of The Total Environment
OCEANS 2021: San Diego – Porto
Marine Alien Invasive Species represent a main global threat tothe conservation of ecosystems, be... more Marine Alien Invasive Species represent a main global threat tothe conservation of ecosystems, being a major driver of biodiversity loss as well as causing important socioeconomic damages. INVHALI is an interdisciplinary national project with the aim of identifying the invasive algae Halimeda incrassata as well as other native species that coexist in the same environment using robots and artificial intelligence on images. This work presents preliminary results on: a) Halimeda incrassata detection and coverage estimation using deep learning neural networks, and b) mosaicking the areas surveyed with the robots. The mean error is estimated on −0.33% when using an object detection neural network and 2.46% when using a semantic segmentation neural network, demonstrating the validity of the used techniques and methodology.
FEMS Microbiology Ecology, Jun 24, 2020
Nutrient addition to eelgrass grown in mesocosm tanks changed the community structure of the root... more Nutrient addition to eelgrass grown in mesocosm tanks changed the community structure of the root-associated microbiome, enriching for populations with sulfur and nitrogen cycling potential.
Marine Environmental Research, Dec 1, 2020
Frontiers in Marine Science, Aug 3, 2021
Herbivory has long been considered an important component of biotic resistance against macroalgae... more Herbivory has long been considered an important component of biotic resistance against macroalgae invasions in marine habitats. However, most of the studies on herbivory of invasive algae refer only to consumption by strictly herbivorous organisms, whereas consumption by omnivorous species has been largely ignored and rarely quantified. In this study, we assess whether the commonest omnivorous sparid species in the Mediterranean Sea are consuming the highly invasive alga, Caulerpa cylindracea, and determine both, its importance in their diet and their electivity toward it as a source of food. Our results confirm that three of the four fish species studied regularly consume C. cylindracea, but in most cases, the importance of C. cylindracea in the diet is low. Indeed, the low electivity values indicate that all species avoid feeding on the invasive alga and that it is probably consumed accidentally. However, despite animals and detritus being the main food for these sparid species, several individual specimens were found to have consumed high amounts of C. cylindracea. This suggests a potential role that these fish species, being really abundant in shallow rocky bottoms, may play in controlling, to some extent, the abundance of the invader.
Marine Pollution Bulletin, Nov 1, 2020
Applied and Environmental Microbiology, Jan 15, 2021
Limnology and Oceanography, Jan 15, 2019
Marine Pollution Bulletin, Sep 1, 2018
There is increasing uncertainty of how marine ecosystems will respond to rising temperatures. Whi... more There is increasing uncertainty of how marine ecosystems will respond to rising temperatures. While studies have focused on the impacts of warming on individual species, knowledge of how species interactions are likely to respond is scant. The strength of even simple two-species interactions is influenced by several interacting mechanisms, each potentially changing with temperature. We used controlled experiments to assess how plant-herbivore interactions respond to temperature for three structural dominant macrophytes in the Mediterranean and their principal sea urchin herbivore. Increasing temperature differentially influenced plant-specific growth, sea urchin growth and metabolism, consumption rates and herbivore preferences, but not movement behaviour. Evaluating these empirical observations against conceptual models of plant-herbivore performance, it appears likely that while the strength of herbivory may increase for the tested macroalga, for the two dominant seagrasses, the interaction strength may remain relatively unchanged or even weaken as temperatures rise. These results show a clear set of winners and losers in the warming Mediterranean as the complex factors driving species interactions change.
Aquaculture Environment Interactions, Dec 3, 2020
Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which in... more Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as 'essential fish habitat', restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.
OCEANS 2021: San Diego – Porto, Sep 20, 2021
This paper describes a new methodology to monitor and assess marine sites of special ecological i... more This paper describes a new methodology to monitor and assess marine sites of special ecological interests, such as, those ecosystems formed by the meadows of Posidonia oceanica. This new procedure includes the use of Autonomous Marine Vehicles (AMV), image processing techniques and Convolutional Neural Networks (CNN) to explore extensive areas colonized with this seagrass, form 2D and 3D maps, and quantity, automatically, the bottom coverage of this species. This new approach starts a new paradigm in the task of qualifying and quantifying the state of certain benthic marine habitats since, compared with traditional and current methods performed by divers, ours decreases costs, infrastructures and personal security measures, and increases the mission time, the size of the covered areas, the amount and quality of gathered data and the accuracy in its later processing.
Phytochemistry, Apr 1, 2022
Differences in phenolic composition across different ontogenic stages can be crucial in determini... more Differences in phenolic composition across different ontogenic stages can be crucial in determining the interaction outcomes between plants and their surrounding biotic environment. In seagrasses, specific phenolic compounds have rarely been analyzed and remain unexplored in ontogenic stages other than non-reproductive adults. Furthermore, it is generally accepted that plants would prioritize defense (e.g., through increased phenolic content) on tissues or stages that are critical for plant fitness but how this affects nutritional quality or plant resources has been scarcely explored. We analyzed how phenolic composition, N and C content and carbohydrate resources varied among different life stages (i.e. old and young leaves of reproductive and non-reproductive plants, and leaves of seedlings) in the seagrass Posidonia oceanica. We identified five phenolic compounds, whose structures were established as hydroxycinnamate esters of tartaric acid. Also, our results show that in all examined ontogenic stages phenolic compounds have the same qualitative composition but inflorescences exhibit higher contents than vegetative tissues. We did not find a reduction in stored resources in reproductive plants, pointing to some kind of compensatory mechanism in the production or storage of resources. In contrast, seedlings seemed to have less phenolic compounds than reproductive plants, perhaps due to limited resources available to allocate to phenolic production. Our results demonstrate how different ontogenic stages change their investment in specialized phenolic compounds prioritizing different functions according to the needs and limitations of that stage.
Marine Pollution Bulletin, Sep 1, 2018
Seedlings are a key life stage in seagrasses, providing genetic diversity and being a useful tool... more Seedlings are a key life stage in seagrasses, providing genetic diversity and being a useful tool for restoration. We examined the influence of increased sediment nutrients and the presence of the invasive macroalga Caulerpa cylindracea on the success of in situ transplanting Posidonia oceanica seedlings in a six-month experiment. Our results indicate that one-year old seedlings successfully survive in the field and their survival and growth are positively affected by the presence of C. cylindracea. Furthermore, nutrient addition in the sediment had positive effects on both C. cylindracea (increasing its cover) and seedlings (increasing leaf development), and the increased C. cylindracea cover did not result in detrimental effects on seedlings. Therefore, biological invasions and nutrient addition do not reinforce each other in the short term to negatively impact transplanted seedlings, which highlights facilitative interactions between invasive algae and native seagrass and provides useful information for successful strategies of seagrass restoration.
Trabajo presentado en la Western Society of Naturalists Meeting, celebrada en San Diego, Californ... more Trabajo presentado en la Western Society of Naturalists Meeting, celebrada en San Diego, California, Estados Unidos, del 11 al 14 de noviembre de 2010
Scientific Reports, Dec 1, 2016
Under future increased CO 2 concentrations, seagrasses are predicted to perform better as a resul... more Under future increased CO 2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO 2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO 2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO 2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed.
Marine Pollution Bulletin, Apr 1, 2019
Science of The Total Environment
OCEANS 2021: San Diego – Porto
Marine Alien Invasive Species represent a main global threat tothe conservation of ecosystems, be... more Marine Alien Invasive Species represent a main global threat tothe conservation of ecosystems, being a major driver of biodiversity loss as well as causing important socioeconomic damages. INVHALI is an interdisciplinary national project with the aim of identifying the invasive algae Halimeda incrassata as well as other native species that coexist in the same environment using robots and artificial intelligence on images. This work presents preliminary results on: a) Halimeda incrassata detection and coverage estimation using deep learning neural networks, and b) mosaicking the areas surveyed with the robots. The mean error is estimated on −0.33% when using an object detection neural network and 2.46% when using a semantic segmentation neural network, demonstrating the validity of the used techniques and methodology.
FEMS Microbiology Ecology, Jun 24, 2020
Nutrient addition to eelgrass grown in mesocosm tanks changed the community structure of the root... more Nutrient addition to eelgrass grown in mesocosm tanks changed the community structure of the root-associated microbiome, enriching for populations with sulfur and nitrogen cycling potential.
Marine Environmental Research, Dec 1, 2020
Frontiers in Marine Science, Aug 3, 2021
Herbivory has long been considered an important component of biotic resistance against macroalgae... more Herbivory has long been considered an important component of biotic resistance against macroalgae invasions in marine habitats. However, most of the studies on herbivory of invasive algae refer only to consumption by strictly herbivorous organisms, whereas consumption by omnivorous species has been largely ignored and rarely quantified. In this study, we assess whether the commonest omnivorous sparid species in the Mediterranean Sea are consuming the highly invasive alga, Caulerpa cylindracea, and determine both, its importance in their diet and their electivity toward it as a source of food. Our results confirm that three of the four fish species studied regularly consume C. cylindracea, but in most cases, the importance of C. cylindracea in the diet is low. Indeed, the low electivity values indicate that all species avoid feeding on the invasive alga and that it is probably consumed accidentally. However, despite animals and detritus being the main food for these sparid species, several individual specimens were found to have consumed high amounts of C. cylindracea. This suggests a potential role that these fish species, being really abundant in shallow rocky bottoms, may play in controlling, to some extent, the abundance of the invader.
Marine Pollution Bulletin, Nov 1, 2020
Applied and Environmental Microbiology, Jan 15, 2021
Limnology and Oceanography, Jan 15, 2019
Marine Pollution Bulletin, Sep 1, 2018
There is increasing uncertainty of how marine ecosystems will respond to rising temperatures. Whi... more There is increasing uncertainty of how marine ecosystems will respond to rising temperatures. While studies have focused on the impacts of warming on individual species, knowledge of how species interactions are likely to respond is scant. The strength of even simple two-species interactions is influenced by several interacting mechanisms, each potentially changing with temperature. We used controlled experiments to assess how plant-herbivore interactions respond to temperature for three structural dominant macrophytes in the Mediterranean and their principal sea urchin herbivore. Increasing temperature differentially influenced plant-specific growth, sea urchin growth and metabolism, consumption rates and herbivore preferences, but not movement behaviour. Evaluating these empirical observations against conceptual models of plant-herbivore performance, it appears likely that while the strength of herbivory may increase for the tested macroalga, for the two dominant seagrasses, the interaction strength may remain relatively unchanged or even weaken as temperatures rise. These results show a clear set of winners and losers in the warming Mediterranean as the complex factors driving species interactions change.