Papers by Francisco Arenas
Invasive species are recognized worldwide as great threats to natural communities and seriously c... more Invasive species are recognized worldwide as great threats to natural communities and seriously compromising the ecosystem services, while sometimes representing useful resources if duly valued. By exploring the knowledge on these species, understanding their dynamics, and predicting their behaviour, eventual prevention and mitigation measures might be addressed to control the presence and abundance of some non-indigenous species (NIS). The session "MARINE INVADERS-assessment and impact on aquatic ecosystems", included in the "International Meeting on Marine Research" (IMMR' 18), held at the Polytechnic of Leiria at the 4 th of July 2018 at Peniche, Portugal, is therefore, an excellent opportunity to gather scientists investigating NIS, exchanging experiences on the state-of-the-art of one of the most hot and trendy issues on global changes. This session aimed to bring into discussion the last findings concerning the latest technics used on the detection of this kind of biological pollution, but also on the quantification, the determination of the specific cellular compounds these NIS are rich in and its economic applicability, but also searching for innovative methods used to measure the negative and positive impact of invasive species on the recipient environment (e.g., competition for space, interference on ecosystems food web, new resource item). This problem, being global, having no borders, and presently in an escalating stage, represents a paramount issue threatening global ecosystems and economies with increasing information and researchers working on the topic. We expect MARINE INVADERS to be a great forum and an opportunity to discuss these topics, reinforcing and widening the dissemination of researcher's findings over the meeting's audience, while also providing the chance to further publish in a special issue of Ecological Indicators Journal, being prepared by the guest editors chairing this session.
Diversity and Distributions, 2021
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Diversity, 2020
Most of the biodiversity studies in the South European Atlantic Shelf ecoregion are limited to sh... more Most of the biodiversity studies in the South European Atlantic Shelf ecoregion are limited to shallow subtidal or intertidal habitats, while deeper reef habitats, also of relevant ecological importance, are particularly understudied. Macroalgal communities, associated fauna, and sea surface temperature were studied in deep reefs (25–30 m) at two locations in this ecoregion: Parcel, North of Portugal (41° N), and Tarifa, Southern Spain (35° N). Specifically, algal assemblages were assessed using biomass collection and associated ichthyofauna was assessed using visual census techniques using scuba. Seawater surface temperature was higher (>3 °C) in the southern region—Tarifa, compared to the northern region—Parcel. Our survey revealed 18 fish species and 23 algae species. The highest abundance of cold-water species (both macroalgae and fish species) was recorded in Parcel and warm-water species were dominant in Tarifa. In light of climate global trends, both regions might experien...
Ecological Indicators, 2020
Coastal ecosystems are subjected to multiple co-occurring anthropogenic stressors which potential... more Coastal ecosystems are subjected to multiple co-occurring anthropogenic stressors which potentially interact to produce complex impacts on the structure and functioning of biological communities. Seagrass meadows are among the most rapidly declining coastal habitats on Earth. In particular, high nutrient loadings, enhanced sedimentation and competition from blooming seaweeds, like the invasive red alga Gracilaria vermiculophylla, are claimed to be associated with this decline. In this study, we tested for individual and potential interactive impacts on the intertidal seagrass Zostera noltei of these three stressors using a factorial field experiment. We measured seagrass shoots density and biomass (both above and below ground seagrass biomass) as proxies of seagrass physical condition. We also examined changes in fauna assemblages. The study suggested that sediment loading had the most detrimental impacts on health of the seagrass meadows. The effect of seaweed addition was negative and denso-dependent. Deleterious effects of nutrient enrichment were less evident. Non-additive interactions were also noticeable for some of the structural traits measured. Particularly, nutrient enrichment changed the effect of the other stressors for some of the responses measured. The effect of the treatments was also perceptible in the associated fauna assemblages. The ubiquitous grazer Peringia ulvae was more abundant in treatments with sediment loading, but those sediment effects in the density of the small grazer were modulated by nutrient and seaweed addition levels. Finally, we suggest that more studies should test for synergistic effects of co-occurring stressors to better understand the direction and intensity of changes triggered by human activities in natural ecosystems.
Scientia Marina, 2011
We investigated the seasonal (winter vs summer and within season) and spatial (between-pool) vari... more We investigated the seasonal (winter vs summer and within season) and spatial (between-pool) variability of benthic assemblages of rock pools at mid-intertidal level along the shore of Viana do Castelo (North Portugal). Physical traits of rock pools, including size, depth and position along the shore, were also compared between pools. While pools did not differ for any of the examined physical traits, results indicated a clear seasonal difference in the structure of assemblages, including a total of 49 macroalgal and 13 animal taxa. This finding was driven by six taxa that are more abundant in winter (the reefforming polychaete Sabellaria alveolata, the articulated coralline algae Corallina spp., the brown alga Bifurcaria bifurcata, the encrusting coralline alga Lithophyllum incrustans, the red alga Chondracanthus acicularis and the grazing snails Gibbula spp.) and four algal taxa that are more abundant in summer (the invasive brown Sargassum muticum, the green Ulva spp., the kelp Laminaria ochroleuca and the filamentous red Ceramium spp.). These data provide a new contribution to the knowledge of rock pool systems and have potential implications for monitoring programmes aimed at assessing ecological modifications related to natural and anthropogenic disturbances and for identifying processes responsible for the variability of rock pool assemblages.
Ecosystem functioning impacts of the invasive seaweed Sargassum muticum (Fucales, Phaeophyceae)
Journal of Phycology, 2013
Ongoing changes in natural diversity due to anthropogenic activities can alter ecosystem function... more Ongoing changes in natural diversity due to anthropogenic activities can alter ecosystem functioning. Particular attention has been given to research on biodiversity loss and how those changes can affect the functioning of ecosystems, and, by extension, human welfare. Few studies, however, have addressed how increased diversity due to establishment of nonindigenous species (NIS) may affect ecosystem function in the recipient communities. Marine algae have a highly important role in sustaining nearshore marine ecosystems and are considered a significant component of marine bioinvasions. Here, we examined the patterns of respiration and light-use efficiency across macroalgal assemblages with different levels of species richness and evenness. Additionally, we compared our results between native and invaded macroalgal assemblages, using the invasive brown macroalga Sargassum muticum (Yendo) Fensholt as a model species. Results showed that the presence of the invader increased the rates of respiration and production, most likely as a result of the high biomass of the invader. This effect disappeared when S. muticum lost most of its biomass after senescence. Moreover, predictability-diversity relationships of macroalgal assemblages varied between native and invaded assemblages. Hence, the introduction of high-impact invasive species may trigger major changes in ecosystem functioning. The impact of S. muticum may be related to its greater biomass in the invaded assemblages, although species interactions and seasonality influenced the magnitude of the impact.
Aquatic Botany, 2014
We tested the ability of juvenile sporophytes of two coexisting kelps native to Portugal, Laminar... more We tested the ability of juvenile sporophytes of two coexisting kelps native to Portugal, Laminaria ochroleuca and Saccorhiza polyschides, to adjust their photosynthesis and respiration to increasing sea water temperatures. These responses were measured for S. polyschides from both the subtidal and the intertidal habitat, and for L. ochroleuca from the intertidal habitat. L. ochroleuca showed a reduced ability to acclimatize to changing conditions, whereas S. polyschides demonstrated a larger physiological flexibility. These findings are connected with the life-history traits of these species. Additionally, optimum temperatures for the primary production of kelps were assessed, indicating higher values for inter-than subtidal S. polyschides. Significant physiological differences between inter-and subtidal S. polyschides were observed, based on metabolic rates of primary production and dark respiration. This study suggests that, under a warming climate scenario, responses can significantly vary for each species, and that L. ochroleuca is more susceptible to ocean warming than S. polyschides, due to larger acclimatization capacity of the latter.
Marine Ecology Progress Series, 2001
Hawkins 1991) and freshwater (e.g. Lock 1993) environments. Such films are 3-dimensional structur... more Hawkins 1991) and freshwater (e.g. Lock 1993) environments. Such films are 3-dimensional structures made up of bacteria, diatoms, cyanobacteria and protozoa embedded in a muco-polysaccharide matrix
PLOS ONE, 2015
Understanding the consequences of fragmentation of coastal habitats is an important topic of disc... more Understanding the consequences of fragmentation of coastal habitats is an important topic of discussion in marine ecology. Research on the effects of fragmentation has revealed complex and context-dependent biotic responses, which prevent generalizations across different habitats or study organisms. The effects of fragmentation in marine environments have been rarely investigated across heterogeneous habitats, since most studies have focused on a single type of habitat or patch. In this study, we assessed the effects of different levels of fragmentation (i.e. decreasing size of patches without overall habitat loss). We measured these effects using assemblages of macro-invertebrates colonizing representative morphological groups of intertidal macroalgae (e.g. encrusting, turf and canopy-forming algae). For this purpose, we constructed artificial assemblages with different combinations of morphological groups and increasing levels of fragmentation by manipulating the amount of bare rock or the spatial arrangement of different species in mixed assemblages. In general, our results showed that 1) fragmentation did not significantly affect the assemblages of macroinvertebrates; 2) at greater levels of fragmentation, there were greater numbers of species in mixed algal assemblages, suggesting that higher habitat complexity promotes species colonization. Our results suggest that predicting the consequences of fragmentation in heterogeneous habitats is dependent on the type and diversity of morphological groups making up those habitats.
Journal of Phycology, 2015
The allocation of resources to different life-history traits should represent the best compromise... more The allocation of resources to different life-history traits should represent the best compromise in fitness investment for organisms in their local environment. When resources are limiting, the investment in a specific trait must carry a cost that is expressed in trade-offs with other traits.
Oceanography and Marine Biology - An Annual Review, 2015
Spatial and temporal variation of kelp forests and associated macroalgal assemblages along the Portuguese coast
Marine and Freshwater Research, 2015
Journal of Sea Research, 2015
Predation is one of the most important factors in determining structure and dynamics of communiti... more Predation is one of the most important factors in determining structure and dynamics of communities on intertidal rocky shores. Such regulatory role may be of special relevance in novel communities resulting from biological invasions. Non-indigenous species frequently escape natural predators that limit their distribution and abundance in the native range. However, biological interactions also can limit the establishment and spread of non-native populations. There is a growing concern that climate change might affect predator-prey interactions exacerbating the ecological impacts of non-indigenous species. However, mechanisms underlying such interactions are poorly understood in marine ecosystems. Here, we explored if past environmental stress, i.e., increasing temperature and decreasing pH, could affect the vulnerability of two mussel prey, the native Mytilus galloprovincialis and the non-indigenous Xenostrobus securis, to predation by the native dogwhelk Nucella lapillus. In addition, we evaluated the consequences on the feeding behaviour of N. lapillus. First, we exposed monospecific assemblages of each mussel species to combined experimental conditions of increasing temperature and decreasing pH in mesocosms for 3 weeks. Then assemblages were placed on a rocky shore and were enclosed in cages with dogwhelks where they remained for 3 weeks. Despite the lack of preference, consumption was much greater on the native than on the invasive mussels, which barely were consumed by dogwhelks. However, this trend was diverted when temperature increased. Thus, under a coastal warming scenario shifts in dogwhelks feeding behaviour may help to contain invader's populations, especially in estuarine areas where these predators are abundant.
Early patterns of recovery from disturbance in intertidal algal assemblages: consistency across regions within a marine province
Marine Ecology Progress Series, 2014
Biodiversity, Taxonomy, Environmental Assessment, and Biotechnology, 2014
Recent shifts in the distribution and abundance of marine macroalgae in the northern Iberian Peni... more Recent shifts in the distribution and abundance of marine macroalgae in the northern Iberian Peninsula and Canarias in response to climate change Palabras clave: cambio climático, biogeografía, macroalgae.
Impact & Feedbacks of Invasion and Climate Change on Algal Assemblages: Experimental Approaches
Interactive Effects of Solar Uvr and Temperature on Three Different Morpho-Functional Macroalgae Grown Under Modified CO2 and Nutrient Regimes
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Papers by Francisco Arenas