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Financiado para publicación en acceso aberto: Universidade de Vigo/CISUG Bivalves and seagrasses can interact through diverse environmentally-modulated mechanisms. To assess the effects of climate warming on bivalve-seagrass interactions, we carried out a pioneering field experiment in which open top chambers (OTCs) were used to increase air and sediment temperature in a shellfish bed in NW Spain during two consecutive spring tides (16 days of exposure to OTCs). The temperature increase produced by OTCs was significant, as observed in the daily maximum and mean temperature and in degree hours, although the difference was greater in air and at the sediment surface (up to 8 ◦C and 3 ◦C, respectively) than at 5 cm depth (up to 1 ◦C). Warming was less acute in boxes with the seagrass Zostera noltei, which acted as a thermal buffer, reducing the mean temperature by 1 ◦C at the sediment surface in OTC boxes and control boxes (without OTCs). Although the short-term increase in temperature did not greatly affect physiological responses of Z. noltei, the carbohydrate reserves and nutrient content increased in the presence of clams. Growth of the native clam Ruditapes decussatus was significantly slower in OTC boxes with bare sediment, and the seagrass thus buffered the negative effect of warming on growth. The presence of Z. noltei may save clams from having to spend energy to burrow deeper to encounter cooler conditions, leaving more energy available for growth. Conversely, growth of the introduced clam R. philippinarum did not differ between habitats or treatments. Our findings confirm a twoway facilitative interaction that may be particularly important in relation to the resilience of both species in the current context of global warming. Ministerio de Ciencia e Innovación | Ref. RTI2018-095583-B-I00 Xunta de Galicia-FEDER | Ref. ED431C 2021/42 Xunta de Galicia | Ref. ED481A- 2020/199 NASA | Ref. 80NSSC20K0074

The increased frequency of heatwaves expected in the context of global warming will affect socio-ecological systems such as shellfish beds at intertidal seagrass meadows. A mesocosm experiment was performed to assess the effects of a simulated atmospheric heatwave during low tide on the bioturbation indicators and growth of the commercial juvenile native Ruditapes decussatus and the introduced clam R. philippinarum, and on their interactions with the seagrass Zostera noltei. Under the heatwave, heat dissipation at 5 cm depth was significantly greater in the sediments below Z. noltei than below bare sand, the photosynthetic efficiency (Fv/Fm) of Z. noltei decreased and the clams tended to grow less. Furthermore, after the heatwave clams below bare sand tended to burrow deeper than those below Z. noltei, indicating that seagrass provided a refuge for clams. Ruditapes philippinarum grew less, and did not burrow as deeply as R. decussatus, which may imply greater vulnerability to desiccation and heat at low tide. The particle displacement coefficient (PDC) of R. philippinarum indicated lower bioturbation values in Z. noltei than in bare sand and was a suitable bioturbation indicator for juvenile Ruditapes spp. clams. In Z. noltei coexisting with R. philippinarum, the Fv/Fm values were higher than without clams after a recovery period, which may be linked to the assimilation of phosphate excreted by the clams and suggests a facilitative interaction. No such interaction was observed with R. deccusatus, probably because of its deeper burrowing depth. The findings suggest reciprocal facilitative interactions between R. philippinarum and Z. noltei and the potential contribution of Z. noltei to the sustainability of clams under global warming scenarios, which may support management actions aimed at enhancing the coexistence between shellfishing activities and seagrass conservation. Agencia Estatal de Investigación | Ref. RTI2018-095583-B-I00 Xunta de Galicia | Ref. ED431C 2021/42 Xunta de Galicia | Ref. ED481A-2020/199 Universidade de Vigo/CISUG

The shifts in soil metabolism as a response to warming and wrack subsidies on Antarctic sedimentary shores have not been studied to date. With this aim, macroalgal deposits, as well as inorganic nutrients and CO2 emission were quantified along the shores of Port Foster, on Deception Island, Antarctic Peninsula. The results indicated a positive relationship between the amount of wrack supplies and sediment metabolism, measured both as CO2 emission through the sediment surface and as amount of inorganic nutrients released to the interstitial pore water. The effect of warming on algal wrack decay was analyzed in a manipulative field experiment where passive open-top chambers (OTCs) were used to increase soil temperature. By doing this, temperature raised by 0.9°C under patches of the red macroalgae Palmaria decipiens, whereas there was an increase of 2.4°C on bare sand. The results indicated that a small warming accelerated mineralization rates of C, N and P of the algal biomass, without significant changes in the bulk of inorganic nutrients released. Over 12 days of experiment, 8.3% of the total C in algal tissues was released as CO2 in the OTC plots, compared to 6.4% at ambient temperature. CO2 emission in bare sand plots warmed with OTCs was three times the amount measured in the ambient plots. Collembola was the dominant soil fauna, with densities negatively affected by warming and positively related to the organic content of sediment. This study confirms the key role of sandy shores in recycling ocean derived organic matter, highlighting the sensitivity of Antarctic ecosystems to a changing scenario of climate change that predicts significant increases in temperature over the next few decades.

Seagrass carbon stocks are vulnerable to physical disturbance. We assessed the effect of clam harvesting on the organic carbon (Corg) stocks in surface sediments in four intertidal Zostera noltei meadows on the Iberian Atlantic coast (Spain and Portugal), by comparing undisturbed and harvested areas. We also monitored the spatial cover of the meadows throughout the growing season. Sedimentary Corg content and Corg stocks were about four times lower in intensively harvested areas than in control areas, but there were not differences between areas with low harvesting pressure and control areas. Reductions of 53–85% in sedimentary Corg stocks of Z. noltei meadows were caused by intensive clam harvesting. The effect of intensive clam harvesting on Corg stocks increased throughout the growing season, but the area covered by the seagrass increased from 21 to 37%, suggesting rapid recovery of seagrass canopies and potential recovery of sedimentary Corg stocks. Financiado para publicación en acceso aberto: Universidade de Vigo/CISUG Agencia Estatal de Investigación | Ref. RTI2018-095583-B-I00 Xunta de Galicia | Ref. ED431C 2021/42 Xunta de Galicia | Ref. ED481A-2020/199 Fundação para a Ciência e a Tecnologia | Ref. UIDB/04326/2020

Biodiversity loss is considered one of the main threats to marine ecosystems. In this framework of biodiversity decline, organisms that provide biogenic habitat play a relevant role by their capacity to structure assemblages and influence ecological processes. The Mediterranean mussel Mytilus galloprovincialis is considered an ecosystem engineer because it alters local environmental conditions maintaining habitat suitability for other organisms, and enhancing local biodiversity. Although it is widely recognized that mussel beds increase diversity, the drivers shaping these assemblages are poorly explored. We investigate whether mussel size homogenisation shapes the abundance, richness and structure of macrobenthic assemblages associated with mussel beds in two shores of the Galician coast (NW Spain). At each shore, two sites, 10 m apart, were selected and at each site, faunal assemblages were compared between mussel clumps showing shells of various sizes (control), and mussel clumps with closely similar-sized mussels, considered as homogenised. Homogenised clumps showed, in general, higher values in total number of individuals and species than control clumps. Regarding the effect of mussel size homogenisation on the multivariate structure of the assemblages, significant differences between control and homogenised clumps were found in three out of the four sites. Most relevant associated species usually reached higher abundances in homogenised clumps than control ones. Therefore, mussel size homogenisation influenced the structure of the macrofaunal assemblages associated with mussel beds but, its effect was context dependent (i.e., varied with sites). Information about the species contribution to dissimilarities among homogenised and control clumps was provided and the potential influence of sediment and algae on mussel clumps was discussed COMPETE 2020, FEDER | Ref. PTDC/CTA-AMB/30181/2017, n. 30181 Fundação para a Ciência e a Tecnologia | Ref. UIDB/ 04423/2020 Fundação para a Ciência e a Tecnologia | Ref. UIDP/04423/2020 Fundação para a Ciência e a Tecnologia | Ref. CEECIND/03893/ 2018

Sampling impediments and paucity of suitable material for molecular analyses have precluded the study of speciation and radiation of deep-sea species in Antarctica. We analyzed barcodes together with genome-wide single nucleotide polymorphisms obtained from double digestion restriction site-associated DNA sequencing (ddRADseq) for species in the family Antarctophilinidae. We also reevaluated the fossil record associated with this taxon to provide further insights into the origin of the group. Novel approaches to identify distinctive genetic lineages, including unsupervised machine learning variational autoencoder plots, were used to establish species hypothesis frameworks. In this sense, three undescribed species and a complex of cryptic species were identified, suggesting allopatric speciation connected to geographic or bathymetric isolation. We further observed that the shallow waters around the Scotia Arc and on the continental shelf in the Weddell Sea present high endemism and diversity. In contrast, likely due to the glacial pressure during the Cenozoic, a deep-sea group with fewer species emerged expanding over great areas in the South-Atlantic Antarctic Ridge. Our study agrees on how diachronic paleoclimatic and current environmental factors shaped Antarctic communities both at the shallow and deep-sea levels, promoting Antarctica as the center of origin for numerous taxa such as gastropod mollusks Harvard University | Ref. NSF DEB-1754278 Fundación Ramón Areces | Ref. beca postdoctoral National Science Foundation | Ref. NSF ANT-1043749

Marine aquaculture releases mollusc shell debris which can accumulate on the seabed. Due to its low degradability, mollusc shell debris becomes integrated into the sediment, modifying both its structure and associated biogeochemical processes. These changes are expected to influence the biological assemblages within the sediment, which play a key role in the biogeochemical processes due to bioturbation. We performed an in-situ experiment to test the effects of mollusc shell-hash on the bioturbation capacity of the macrofaunal assemblages within the sediments affected by marine aquaculture. The aquaculture facilities chosen were a fish farm in an oligotrophic area of the Mediterranean over a sandy sediment, and a mussel farm in the Atlantic located in an estuary over silty sediment. Mollusc shell-hash promoted macrofaunal assemblages with a high bioturbation potential, regardless of the influence of aquaculture. Nevertheless, in the sediment from the mussel-farm, the shell-hash did not have a marked effect on the macrofaunal assemblages. The effect of shell-hash on promoting macrofaunal communities with a high bioturbation potential capacity is therefore dependent on the existing environmental conditions in the area, including the natural organic matter input and grain size of the sediment. Shell-hash could be used a strategy to improve the ecosystem function of sediments as a circular economy-oriented management practice. This research was funded by the project CGL2015-70136-R from the Spanish National Agency for Research (MINECO/FEDER). CS was funded by the University of Alicante (Ref. UATALENTO 17-11).

Invasive macroalgae represent one of the major threats to marine biodiversity, ecosystem functioning and structure, as well as being important drivers of ecosystem services depletion. Many such species have become well established along the west coast of the Iberian Peninsula. However, the lack of information about the distribution of the invaders and the factors determining their occurrence make bioinvasions a difficult issue to manage. Such information is key to enabling the design and implementation of effective management plans. The present study aimed to map the current probability of presence of six invasive macroalgae: Grateloupia turuturu, Asparagopsis armata, Colpomenia peregrina, Sargassum muticum, Undaria pinnatifida, and Codium fragile ssp. fragile. For this purpose, an extensive field survey was carried out along the coast of the north-western Iberian Peninsula. Species distribution models (SDMs) were then used to map the presence probability of these invasive species throughout the study region on the basis of environmental and anthropogenic predictor variables. The southern Galician rias were identified as the main hotspots of macroalgal invasion, with a high probability of occurrence for most of the species considered. Conversely, the probability of presence on the Portuguese coast was generally low. Physico-chemical variables were the most important factors for predicting the distribution of invasive macroalgae contributing between 57.27 and 85.24% to the ensemble models. However, anthropogenic factors (including size of vessels, number of shipping lines, distance from ports, population density, etc.) considerably improved the estimates of the probability of occurrence for most of the target species. This study is one of the few to include anthropogenic factors in SDMs for invasive macroalgae. The findings suggest that management actions aimed at controlling these species should strengthen control and surveillance at ports, particularly in southern Galician rias. Early detection should be of main concern for risk assessment plans on the Portuguese coast., A. B. was supported by the Axencia Galega de Innovación (GAIN), Xunta de Galicia (grant ED481B 2018/68). This work was supported by the European Union through EASME Blue Labs project AMALIA—Algae-to-MArket Lab IdeAs (EASME/EMFF/2016/ 1.2.1.4/03/SI2.750419). The authors acknowledge financial support provided by the Portuguese Foundation for Science and Technology (FCT) through Strategic Project UID/MAR/04292/2019 granted to MARE – Marine and Environmental Sciences Centre, through MARINE INVADERS Project (PTDC/BIA-CBI/31144/2017), co-financed by COMPETE (POCI-01-0145-FEDER-031144), and the Integrated Programme of SR&TD “Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate” (reference Centro-01-0145- FEDER-000018), co-funded by Centro 2020 program, Portugal 2020, European Union, through the European Regional Development Fund.

The abundance and distribution of intertidal canopy-forming macroalgae are threatened by the increase in sea surface temperature and in the frequency and intensity of heatwaves caused by global warming. This study evaluated the physiological response of predominant intertidal macroalgae in the NW Iberian Peninsula (Bifurcaria bifurcata, Cystoseira tamariscifolia and Codium tomentosum) to increased seawater temperature during immersion and increased air temperatures during consecutive emersion cycles. We combined field mensuration and laboratory experiments in which we measured mortality, growth, maximum quantum yield and C:N content of the macroalgae. Air temperature was a critical factor in determining physiological responses and survivorship of all species, whereas high seawater temperature had sublethal effects. Cystoseira tamariscifolia suffered the greatest decreases in Fv/Fm, growth and the highest mortality under higher air temperatures, whereas C. tomentosum was the most resistant and resilient species. Two consecutive cycles of emersion under atmospheric heatwaves caused cumulative stress in all three macroalgae, affecting the physiological performance and increasing the mortality. The potential expansion of the warm-temperate species B. bifurcata, C. tamariscifolia and C. tomentosum in the NW Iberian Peninsula in response to increasing seawater temperature may be affected by the impact of increased air temperature, especially in a region where the incidence of atmospheric heatwaves is expected to increase.

Microbial biofilms can be key mediators for settlement of macrofoulers. The present study examines the coupled effects of microbial biofilms and local environmental conditions on the composition, structure and functioning of macrofouling assemblages. Settlement of invertebrates over a gradient of human-impacted sites was investigated on local biofilms and on biofilms developed in marine protected areas (MPAs). Special attention was given to the presence of non-indigenous species (NIS), a global problem that can cause important impacts on local assemblages. In general, the formation of macrofouling assemblages was influenced by the identity of the biofilm. However, these relationships varied across levels of anthropogenic pressure, possibly influenced by environmental conditions and the propagule pressure locally available. While the NIS Watersipora subatra seemed to be inhibited by the biofilm developed in the MPA, Diplosoma cf. listerianum seemed to be attracted by biofilm developed in the MPA only under mid anthropogenic pressure. The obtained information is critical for marine environmental management, urgently needed for the establishment of prevention and control mechanisms to minimize the settlement of NIS and mitigate their threats. Xunta de Galicia | Ref. I2C-B Xunta de Galicia | Ref. FEDER ED431D 2017/20 Xunta de Galicia | Ref. ED431C 2017/46 Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação (ARDITI) | Ref. M1420-09-5369-FSE-000001 European Regional Development Fund | Ref. M1420-01-0145-FEDER-000001 Fundação para a Ciência e Tecnologia | Ref. UIDB/04292/2020 Fundação para a Ciência e a Tecnologia | Ref. CEECINST/00098/2018

This work was supported by the European Union through EASME Blue Labs project AMALIA - Algae-to-MArket Lab IdeAs (EASME/EMFF/2016/1.2.1.4/03/SI2.750419). Further support was provided by Fundação para a Ciência e a Tecnologia (FCT) through the Strategic Project UID/MAR/04292/2013 and project MARINE INVADERS – The impact and mechanisms of success of the invasive seaweed Asparagopsis armata on coastal environments (POCI-01-0145-FEDER-031144). The project was also partly funded by the Integrated Programme of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018) cofunded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund, and Operational Programme MAR2020 through project MACAU (MAR-04.03.01-FEAMP-0128). These funding bodies were not directly involved in the development of the current study. Data on the number of licences and people landing in the Berlengas Natural Park were provided by Instituto da Conservação da Natureza e das Florestas and Life Berlengas, LIFE13/NAT/PT/000458, funded by LIFE program. The authors thank J. Pascual for assistance during SCUBA diving fieldwork, A. R. Larrinaga for developing the distribution maps, and E. Pérez and A. Fuentes for their assistance in laboratory sampling Marine ecosystems are facing major anthropogenic disturbances, including loss of biodiversity, eutrophication, and biological invasions. Thus, attention has raised on marine conservation actions to preserve habitat resilience and biodiversity. Marine Protected Areas (MPAs) play an essential role in marine conservation as they are usually designated to provide marine ecosystem resilience of native communities to human-induced impacts (including non-native introductions) while contributing with positive effects on other ecosystem services. The introduction of a new species in novel marine habitats has been attributed to biotic, abiotic, and anthropogenic factors. In the present study, the effects of native functional diversity, wave exposure were studied, and for the first time, marine protection was addressed concerning the invasion success of six macroalgae in two MPAs in the NW Iberian Peninsula. The correlation between the presence/absence of some native functional groups and the invasion success of some invasive species highlighted the importance of conserving native canopy-formers. Despite local differences, wave exposure did not affect invasion success. The protection provided by both MPAs was very limited to prevent the establishment and spread of the most abundant invasive macroalgae. Therefore, stricter management plans should be implemented to ensure native ecosystem resilience within the MPAs. info:eu-repo/semantics/publishedVersion

Temporal variation patterns and bioturbatory activity of polychaete assemblages have been insufficiently studied. Two subtidal fine-sediment sites have been sampled in order to describe and compare polychaete temporal variation patterns. In order to estimate bioturbation potential (BP), a new approach is proposed that aims maximum versatility for comparative studies. Both assemblages differed significantly in terms of temporal variation of sedimentary and faunal attributes. The most exposed site was dominated by species characteristic of muddy-fine sand and presented a seasonal pattern with higher densities and BP values from mid-summer to early winter. The most sheltered and muddy site was dominated by Paradoneis lyra and presented an irregular temporal variation. Signs of moderate organic enrichment were found, particularly in the less exposed site. Spatial and temporal variations appear to be related to sediment features and hydrodynamic stress, which also affect BP of each assemblage. Our results suggest that the bioturbatory activity of polychaetes is more extensive and relevant in finer sediments.

Due to the economic importance of the mussel Mytilus galloprovincialis in the Spanish aquaculture, there is a growing interest in developing alternative methods to ensure the supply of good-quality biological material and to minimize the uncertainty and variability that might be a source of economic risk for this sector. The aim of this work was to develop a successful cryopreservation protocol for Mytilus galloprovincialis larvae and study long-term effects by assessing survival and development post cryobanking. We evaluated the effect of previously studied cryoprotecting agent, Ethylene glycol (EG) for cryopreservation of trochophore larvae and D-veliger larvae 48 h and 72 h old, following an existing preliminary protocol for M. galloprovincialis mussel trochophores. The protocol selected for cryopreservation consisted on holding at 4 °C for 2 min, then cooling at 1 °C/min to −12 °C, holding for 5 min, then cooling at −35 °C with a rate of 1 °C/min, then plunging into liquid nitrogen for storage. Thawing took place by immersion in 35 °C water bath. With this protocol the initial percentage of short-term developed a D-larvae (48 h incubation post-thaw) was 48.9 ± 7.6% with 10% EG + 0.2 M Trehalose (TRE). This initial test only studied the trochophore larvae until they reached the D-stage (48 h old); in the present experiment experiments, we replicated this study but also carried out a long-term larval rearing with cryopreserved trochophore larvae in comparison to fresh larvae. This experiment allowed a comparative post-freezing analysis of both larval development and survival. Larval settlement was also characterized after 13 days. The data revealed that until settling, the survival of the cryopreserved larvae was slightly lower than the 2.8% reported in the larval rearing for Greenshell™ mussel. Over time, there was an initial difference in size of cryopreserved larvae when compared to controls, but from day 17 onwards the size between both types of larvae began to stabilize. Attending to settlement, we obtained a 64% of success of cryopreserved larvae respect to the control.

Spatial variability of environmental factors and macrobenthos, using species and functional groups, was examined over the same scales (100s of cm to >100 km) in intertidal sediments of two transitional water systems. The objectives were to test if functional groups were a good species surrogate and explore the relationship between environmental variables and macrobenthos. Environmental variables, diversity and the multivariate assemblage structure showed the highest variability at the scale of 10s of km. However, abundance was more variable at 10s of m. Consistent patterns were achieved using species and functional groups therefore, these may be a good species surrogate. Total carbon, salinity and silt/clay were the strongest correlated with macrobenthic assemblages. Results are valuable for design and interpretation of future monitoring programs including detection of anthropogenic disturbances in transitional systems and propose improvements in environmental variable sampling to refine the assessment of their relationship with biological data across spatial scales.

DNA metabarcoding provides a rapid and effective identification tool of macroinvertebrate species. The accuracy of species-level assignment, and consequent taxonomic coverage, relies on comprehensive DNA barcode reference libraries, which, due to incompleteness, are currently a recognized limitation for metabarcoding applications. In this study, we assembled a comprehensive reference library of DNA barcodes for Atlantic Iberia marine macroinvertebrate species, assessed gaps in species coverage and examined data ambiguities. Initially, an Iberian species checklist for the three dominant groups of marine macroinvertebrates was compiled, comprising 2827 species (926 Annelida, 638 Crustacea and 1263 Mollusca). A total of 18162 DNA sequences of the cytochrome c oxidase subunit I barcode region (COI-5P) matching the species checklist were compiled in a BOLD dataset, where taxonomic discordances were evaluated and cases of deep intraspecific divergence flagged. Gap-analysis showed that 63% of the Iberian macroinvertebrate species still lack a DNA barcode. Coverage gaps varied considerably across taxonomic groups with Mollusca displaying the highest sequence representation in the dataset (427 species, 49% of the total number of sequences), and Crustacea the highest species coverage with 338 species barcoded (53% of the checklist). In contrast, Polychaeta displayed the lower levels of completion (288 species, 16% of the total number of sequences). In total, 1545 Barcode Index Numbers (BINs) were assigned to 1053 barcoded species, of which 66% were taxonomically concordant, 26% displayed multiple BINs and 8% were discordant. Overall, results show that there is still a large portion of marine invertebrate taxa in this region of Europe pending barcode coverage, even considering only the dominant groups. However, the most notable finding was the relevant proportion of species flagged for significant intraspecific divergence and possible hidden diversity. The annotated reference library and gap-analysis here provided can there, This study was supported by the project The NextSea [NORTE-01-0145-FEDER-000032], under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was supported by the "Contrato-Programa'' UIDB/04050/2020 funded by national funds through the FCT I.P. SD and PEV work was supported by national funds through the Portuguese Foundation for Science and Technology (FCT, I.P.) in the scope of the project NIS-DNA [PTDC/BIA-BMA/29754/2017]. BRL benefitted from an FCT fellowship PD/BD/127994/2016. MALT benefitted from an FCT fellowship co-financed by European Social Fund (ESF) SFRH/BD/131527/2017.

The Ninth Symposium on Polar Science/Ordinary sessions: [OB] Polar biology, Wed. 5 Dec. / 2F Auditorium, National Institute of Polar Research

EASME/EMFF/2016/1.2.1.4/016 Negative impacts of marine invasions include loss of genetic diversity, ecosystem functions/processes, and/or community structure and, consequently, a threat to global biodiversity through biotic homogenization. Recent studies indicate that invasive macroalgae make up a significant proportion of marine invasive species. Marine Protected Areas (MPAs) have been proved to have positive effects on marine biodiversity conservation; however, their role in preventing biological invasions, especially macroalgae, is still poorly understood. In this context, we studied the effects of protection and wave exposure on the abundance of six invasive macroalgae (Grateloupia turuturu, Asparagopsis armata, Colpomenia peregrina, Sargassum muticum, Undaria pinnatifida, and Codium fragile ssp. fragile) at two MPAs of the western Iberian Peninsula, one located along the Spanish coast (Illas Atlánticas) and the other on the Portuguese coast (Berlangas). The results showed opposite effects of protection and wave-exposure at the two MPAs. Greater biomass of invasive macroalgae was found at semiexposed areas outside the reserve in the Spanish MPA, whereas in the Portuguese reserve, biomass (especially of A. armata) was significantly greater inside the reserve, mainly at semiexposed sites. These differences highlight the importance of understanding the functioning of reserves to apply proper conservation management policies in order to preserve the MPAs resilience. info:eu-repo/semantics/publishedVersion

Poor physiological acclimatization to climate change has led to shifts in the distributional ranges of various species and to biodiversity loss. However, evidence also suggests the relevance of non-climatic physical factors, such as light, and biotic factors, which may act in interactive or additive way. We used a mechanistic approach to evaluate the ecophysiological responses of four seaweed species (three dominant intertidal fucoids, Fucus serratus, Ascophyllum nodosum, Bifurcaria bifurcata, and the invasive Sargassum muticum) to different conditions of grazing, light irradiance and ultraviolet (UV) radiation. We performed a large-scale mesocosm experiment with a total of 800 individual thalli of macroalgae. The factorial experimental design included major algal traits, photoacclimation, nutrient stoichiometry and chemical defence as response variables. Few significant effects of the factors acting alone or in combination were observed, suggesting a good capacity for acclimatization in all four species. The significant effects were generally additive and there were no potentially deleterious synergistic effects between factors. Fucus serratus, a species currently undergoing a drastic contraction of its southern distribution limit in Europe, was the most strongly affected species, showing overall lower photosynthetic efficiency than the other species. The growth rate of F. serratus decreased when UV radiation was filtered out, but only in the presence of grazers. Moreover, more individuals of this species tended to reach maturity in the absence of grazers, and the nitrogen content of tissues decreased under full-spectrum light. Only the phlorotannin content of tissues of B. bifurcata and of exudates of A. nodosum, both slow-growing species, were positively affected by respectively removal of UVB radiation and the presence of grazers. The findings for S. muticum, a well-established invasive seaweed across European coasts, suggested similar physiological response of this fast-growing species to different levels of grazing activity and light quality/intensity. As expected, this species grew faster than the other species. Bifurcaria bifurcata and A. nodosum only showed minor effects of light quality and grazing on phlorotannins content, which suggests good resistance of these two long-lived species to the experimental conditions. Mechanistic approaches that are designed to analyse interactive effects of physical and biotic factors provide an understanding of physiological responses of species and help to improve the confidence of predictive distribution models.

The Ria de Vigo is a semi-enclosed bay with high primary productivity due to the influence of coastal upwelling-downwelling dynamics. The area is heavily populated and affected by numerous human activities, which lead to sediment modification. Epibenthic megafauna from the non-estuarine zones of this bay has been studied in order to describe its spatial distribution, testing possible differences between inner and outer areas. With that purpose, 75 sites have been sampled by means of a towing dredge. Megafauna was identified to the lowest taxonomic level possible, and each taxon counted and weighted. 113 different taxa were identified and a high spatial heterogeneity was observed in terms of abundance, biomass, taxa richness, diversity and evenness. Suspension-feeding molluscs dominated the innermost part of the studied area, and were substituted by echinoderms towards the external zones; this spatial pattern was also reflected in the results of multivariate analyses. These shifts in taxonomic and trophic guild composition of the assemblages have been tentatively related to differences in pollution levels and primary productivity along the main axis of the bay.

Antarctic benthos has been a main target in Antarctic research, but very few quantitative studies have been carried out in the littoral zone, which may be seasonally covered by macroalgae. In this work, we studied (1) cover and biomass of the macroalgae Iridaea cordata and Adenocystis utricularis, and (2) composition of macrobenthic assemblage associated with these macroalgal species at three locations at King George Island: Mareograph Beach (1 M), Tank’s Bay (2R) and Ardley Bay (3R). Iridaea cordata was collected by completely detaching the algae from the substrate, while A. utricularis was scraped. Adenocystis utricularis covered more than 80 % of the substrate at all locations, while coverage of Iridaea cordata was below 53 % or absent (3R). Fresh biomass of I. cordata was 0.8–61.4 g/individual and 4.7–93.0 g/100 cm2 for A. utricularis. The assemblage associated with both macroalgae differed significantly between sites. The studied fauna was composed mainly of amphipods, gastropods and bivalves. Species diversity was higher in the community associated with A. utricularis. A total of ~27 ind/g DW were found associated with I. cordata, while ~112 ind/g DW were found associated with A. utricularis. The most abundant groups associated with I. cordata were amphipods at 1 M (57 %) and gastropods at 2R (46 %). Both groups were responsible for the dissimilarity between localities (62.50 %). The most abundant groups associated with A. utricularis were the gastropods at all localities reaching up to 82 % at 1 M. This study provides a first baseline on the diversity and abundance of benthic assemblages associated with intertidal macroalgae in the southwest of King George Island.

Within the COST action EMBOS (European Marine Biodiversity Observatory System) the degree and variation of the diversity and densities of soft-bottom communities from the lower intertidal or the shallow subtidal was measured at 28 marine sites along the European coastline (Baltic, Atlantic, Mediterranean) using jointly agreed and harmonized protocols, tools and indicators. The hypothesis tested was that the diversity for all taxonomic groups would decrease with increasing latitude. The EMBOS system delivered accurate and comparable data on the diversity and densities of the soft sediment macrozoobenthic community over a large-scale gradient along the European coastline. In contrast to general biogeographic theory, species diversity showed no linear relationship with latitude, yet a bell-shaped relation was found. The diversity and densities of benthos were mostly positively correlated with environmental factors such as temperature, salinity, mud and organic matter content in sediment, or wave height, and related with location characteristics such as system type (lagoons, estuaries, open coast) or stratum (intertidal, subtidal). For some relationships, a maximum (e.g. temperature from 15–20°C; mud content of sediment around 40%) or bimodal curve (e.g. salinity) was found. In lagoons the densities were twice higher than in other locations, and at open coasts the diversity was much lower than in other locations. We conclude that latitudinal trends and regional differences in diversity and densities are strongly influenced by, i.e. merely the result of, particular sets and ranges of environmental factors and location characteristics specific to certain areas, such as the Baltic, with typical salinity clines (favouring insects) and the Mediterranean, with higher temperatures (favouring crustaceans). Therefore, eventual trends with latitude are primarily indirect and so can be overcome by local variation of environmental factors.

In this paper we evaluated the composition and abundance of molluscs associated with beds of the red algae Gigartina, located in the South Shetland Islands (Antarctic Peninsula) and the Strait of Magellan (southern Chile). During the summer season of 2013, samples were obtained by scuba diving using a 0.25 m2 quadrat, arranged randomly within the bed. We extracted a total of 15 quadrats per sampling site. For Antarctic Peninsula beds the most abundant species were the bivalve Lissarca miliaris (233 individuals) and the gastropod Laevilacunaria antarctica (94 individuals), while for Strait of Magellan beds the most abundant species was the polyplacophoran Callochiton puniceus (36 individuals). Comparative analysis between the two molluscan assemblages showed significant differences in the faunal composition between the Antarctic Peninsula and Strait of Magellan (f = 64.474; p = 0.0001). Therefore, molluscs reported in both areas are characteristic of their respective biogeographic area. Finally, Gigartina species play an important role in the formation of patterns of abundance and diversity of the communities associated with them.

Uromunna naherba sp. nov. is described from eelgrass beds (Zostera marina and Z. noltii) of the NW Iberian Peninsula. This is the second species of the genus reported from the NE Atlantic, after U. petiti. The new species was more abundant on rhizomes than on the leaves of the plants. Seasonal samples show that ovigerous females are present throughout the year, but become more abundant in late spring and summer, when adult males decrease in frequency. Ovigerous females appear in only one size class. Owing to the yearly productivity cycle of the eelgrasses, these data suggest that the species is semelparous and completes its lifecycle within 1 year. The taxonomic characters of the genus are discussed.

Subtidal sediments of Isla del Coco (Cocos Island), Costa Rica were described in their grain size, sorting, organic matter, and carbonates from 27 dredge samples (3–75 m), collected in April 2010. The organic matter range between 1.37–3.31% and carbonates presented a mean of 74±17%. The sorting was moderately or poorly. The grain size ranged between 0.1–1.1mm. The pattern is that sediment change from inner to mouth of bays. Carbonates and gravel fractions increased offshore and organic matter have high values inner the bays. Input of vegetal debris and mud was from the rivers of this island covered with rain and cloud forest.

The mollusc assemblages inhabiting two fine-sediment bottoms in the Ria de Aldan (NW Iberian Peninsula) were quantitatively sampled to test hypotheses about influence of sediment in faunal composition, seasonal variation and amensalist relationships. Both trophic guilds and life habits were considered for functional group classifications of the mollusc species found. The two assemblages were found to have differences in both numerically dominant species and general structure. Among numerically dominant species, Kurtiella bidentata was the only one present in numbers at both sites; it was second to Chamelea striatula at the site with the coarsest sediment and the top dominant at the one which had higher organic content, there followed by Thyasira flexuosa. There were significant changes in abundance, number of species and diversity indexes during the study period; maximum values of abundance occurred in autumn. Seasonal variations in univariate faunal parameters and functional groups were also correlated with those in sediment features and sediment heterogeneity was identified as a key factor to explain diversity of the assemblages. The extensive mussel raft culture in the area seemed not to affect negatively either abundance or diversity and might favour higher diversity by increasing the heterogeneity of the sediment through the supply of mussel shells. Hydrodynamic regime of the embayment is suggested to be a relevant factor in determining differences between the structures of assemblages. Seasonal changes in this regime would lead to major changes in the characteristics of the sediment and therefore in the mollusc assemblages. Higher intensity and frequency of these changes seem to promote a closer relationship between the assemblage and the sediment, as well as a tighter coupling between functional and taxonomic structure of the former. The existence of amensalist relationships was dismissed for both assemblages as no negative relationships between trophic guilds were found.