Works presented

Summary
The Norway lobster, Nephrops norvegicus (Linnaeus, 1758) is a species of great commercial interest with a long tradition of exploitation in Galician waters that has experienced a great decline in recent decades. These organisms have a very limited capacity for movement, living in burrows dug in the sediment which its nature being one of the parameters that determine their presence by conditioning the construction of these structures. The following work seeks to analyse the relationship between the population density of the Norway lobster in Galicia (subdivided into two sections (north and south) differentiated by the 43rd parallel north), the percentage of fine sediment fraction (sampled using two methods: collector and dredge) and other abiotic parameters. It has been found that the presence and abundance of the Norway lobster in the north and south is conditioned by the percentage of silt and clay. Furthermore, a dome-type relationship has been observed between the abundance of Norway lobsters and the percentage of the fine fraction in the northern area sampled by collector, while in the southern area this relationship is less evident. In addition, a non-linear relationship with depth and a marked decline over time in Norway lobster’s abundance have been observed.

Direction
DOMINGUEZ CONDE, JESUS (Tutorships)
Otero Villar, Jaime (Co-tutorships)
González Herraiz, Isabel (Co-tutorships)

Court
BESTEIRO RODRIGUEZ, MARIA CELIA (Chairman)
BALBOA MENDEZ, SABELA (Secretary)
Rodriguez Diaz, Miguel Angel (Member)

Summary
This study analyzed the abundance and diversity patterns of the demersal species community along the northwest coast of Galicia, linking them with environmental, temporal, and spatial factors. Data from the Cigala Sentinel Campaigns conducted between 2017 and 2022 were used, covering a bathymetric range between 111 and 530 m. Abundance analyses were performed for the entire community and separately for each of the described taxonomic groups: osteichthyes, chondrichthyes, crustaceans, cephalopods, echinoderms, and others. All groups showed a significant relationship with depth, but no effect was observed for the entire community as a whole. Over the time series, a significant increase in general abundance and by group was detected, although methodological limitations should be considered when interpreting the results. The fishing area El Fondón and the northern part of Cape Finisterre recorded the highest diversity points in our study, with the latter being an area characterized by strong upwellings that result in high primary productivity.

Direction
DOMINGUEZ CONDE, JESUS (Tutorships)
Otero Villar, Jaime (Co-tutorships)
González Herraiz, Isabel (Co-tutorships)

Court
BESTEIRO RODRIGUEZ, MARIA CELIA (Chairman)
BALBOA MENDEZ, SABELA (Secretary)
Rodriguez Diaz, Miguel Angel (Member)

Summary
Determining the age of fish in natural environments is crucial for understanding their biology and ecology, and otoliths, by recording growth rings, represent a valuable tool in this process. However, their reliability must be validated for each species. This study analyzes the use of otoliths as a method for estimating age in zebrafish (Danio rerio) and their relationship with the organism’s actual growth. Zebrafish possess three pairs of otoliths (lapillus, asteriscus, and sagitta), but due to the fragility of the sagitta, the analysis focused on the first two. The results show that the lapillus is the most suitable otolith for age estimation, as its ring count correlates better with the fish’s actual age (R² lapillus = 0.6909 vs. R² asteriscus = 0.6481). However, the growth models generated indicate that while the lapillus predicts a more accurate maximum length (L∞ = 2.87 cm vs. 2.96 cm in the real model), it overestimates the growth rate (k = 8.46 years vs. 2.03 years in the real model), suggesting that it grows faster in proportion to the fish. On the other hand, the asteriscus predicts a growth rate closer to the actual one (k = 2.79 years) but overestimates the expected maximum length (L∞ = 3.95 cm vs. 2.96 cm in the real model). This suggests that while the asteriscus is optimal for predicting age, it does not accurately reflect the organism’s final size. Given the number of fish used (18), these data and the reliability of the models obtained could be improved by increasing the sample size, including older fish, and optimizing ring visualization techniques. In this regard, experiments were conducted using stains such as alizarin red (ARS) and tetracycline (TC-H), which are incorporated into the otolith during growth. However, the results were also insufficient, requiring better concentration adjustments. Overall, the results indicate that otolith growth in zebrafish follows an allometric pattern and suggest that the periodicity of ring formation changes with age: in young individuals (less than 94 days), rings appear almost daily, while in adults (over 371 days), they form every 2–3 days, which could be affecting the accuracy of age estimates. In conclusion, although the lapillus emerges as the best age indicator in zebrafish, its use still requires adjustments to improve accuracy. Future research should focus on optimizing ring reading and refining growth models to achieve more reliable estimates.

Direction
DOMINGUEZ CONDE, JESUS (Tutorships)
Rey Sanz, Javier (Co-tutorships)
Marí Beffa, Manuel (Co-tutorships)

Court
BESTEIRO RODRIGUEZ, MARIA CELIA (Chairman)
BALBOA MENDEZ, SABELA (Secretary)
Rodriguez Diaz, Miguel Angel (Member)

Summary
Climate change-induced marine heatwaves (MHWs) and habitat fragmentation are increasingly recognised as key drivers of ecological shifts in marine benthic ecosystems. This study investigates the individual and interactive effects of MHWs and habitat fragmentation on community dynamics, recovery potential, and vulnerability to biological invasions. Using Autonomous Reef Monitoring Systems (ARMS), benthic samples were collected from Faro de las Puercas (Gulf of Cádiz) to establish baseline conditions. Subsequently, synthetic assemblages were exposed to controlled mesocosm experiments simulating moderate (24C) and extreme (28C) MHW scenarios alongside habitat Fragmentation treatments. Finally, non-fragmented assemblages were deployed in a marina environment to assess post-disturbance recovery under natural conditions. Results from the mesocosm phase revealed that MHWs and fragmentation significantly influenced benthic community composition but had no significant effect on species richness or diversity indices. Fragmentation modified species distribution, increasing community heterogeneity without necessarily reducing biodiversity. No clear synergistic interaction between MHWs and fragmentation was observed, suggesting these stressors act independently. The post-experimental marina phase revealed the recruitment of five new species, including Bugula neritina (Linnaeus, 1758) and Clavelina cf. oblonga Herdman, 1880. Overall, the findings highlight that while MHWs alter species composition and habitat fragmentation reshapes structural heterogeneity, their combined impact does not exacerbate these effects. The lack of significant interactions between these stressors suggests that community responses may be mediated by species-specific tolerances rather than purely additive or synergistic effects.

Direction
DOMINGUEZ CONDE, JESUS (Tutorships)
Gestoso García, Ignacio José (Co-tutorships)
Carmona Barnosi, Leila María (Co-tutorships)

Court
BESTEIRO RODRIGUEZ, MARIA CELIA (Chairman)
BALBOA MENDEZ, SABELA (Secretary)
Rodriguez Diaz, Miguel Angel (Member)

Summary
The Kentish plover (Charadrius alexandrinus L) population in Galicia are experiencing a downfall in their numbers. This Galician population is mostly on a permanent resident status the year round, hence studying its distribution not only as a breeding species, but also as a wintering population is accurate. This research aims to determine the environmental factors (physical and meteorological) that hold influence in the presence and abundance of this species in the Galician shoreline during winter. The presence of this Kentish plover is determined by climatic factors regarding temperature, such as the daily range of temperature and the annual average temperature, whereas the variables concerning precipitation do not seem to conditionate the presence of this species in the Galician shoreline. Aside, the abundance can be explained by physical factors, which characterize the beaches where most individuals can be spotted. Beaches associated with lagoons and with larger spans have proved to be the factors that influence the most in the wintering populations. Contrarily, the presence of dune vegetation has shown a negative influence in the abundance of Kentish plover populations.

Direction
DOMINGUEZ CONDE, JESUS (Tutorships)

Court
FERNANDEZ ESCRIBANO, JOSE ANGEL (Chairman)
BASELGA FRAGA, ANDRES (Secretary)
ROMERO BUJAN, MARIA INMACULADA (Member)

Summary
The production and release of defensive chemical compounds is a strategy employed by plants to protect themselves against their aggressors. In pines, the production and emission of terpenes are key functions in both direct and indirect resistance. However, there is limited knowledge about the factors that modulate the emission of these compounds. Advances in this field could lead to interesting applications for improving forest health. In this study, we experimentally investigated studied changes in terpene emission and foliar content following the induction of defenses in pine seedlings. The induction was carried out by applying methyl jasmonate (MeJa), an important phytohormone involved in herbivore damage signaling. We used plants from four families, which allowed for the collection of information regarding genetic variation. We selected 32 seedlings from four half-sister families. The experiment was conducted in four blocks, each containing two plants from each family (n=8), in a growth chamber. The volatiles were collected using carbon traps connected to air flow pumps. Sampling of volatile and foliar terpenes was carried out before and five days after the application of MeJa at a low concentration (5 mM). The solution was applied to half of the plants. The mono- and sesquiterpenes in needles and carbon traps were analyzed by gas chromatography with flame ionization detector (GC-FID). To identify the influence of variables on terpene levels, we applied generalized linear models (GLM) with fixed effects, and the correlation coefficient was calculated based on Pearson’s model. Upon analyzing the constitutive defenses (before induction), we found a significant family effect on the concentration of total terpenes, monoterpenes, and sesquiterpenes. Five days after the induction application, no significant changes were found in foliar concentration, although greater variation was observed between plants. The family effect on concentration remained for total terpenes and monoterpenes, and furthermore, a significant interaction effect between family and treatment was identified for these two categories. The induction resulted in a significant increase in the emission of monoterpenes and total terpenes, with the emission rate in induced plants being 3.6 times higher than in controls. We found a significant correlation between foliar concentration and the induced emission rate only for the monoterpene 3-carene, which was not observed for the other compounds. Terpene emission appears to be a rapid and MeJa-dependent induced mechanism, activated even when exposed to low MeJa concentrations. The family effect has a strong influence on the concentration of volatile terpenes in the leaves and persists after 5 days of plant exposure to low MeJa concentrations. The FamxMeJa interaction indicates a different sensitivity to MeJa between families that should be considered. The experimental procedure appears to be appropriate for future studies.

Direction
FERNANDEZ ESCRIBANO, JOSE ANGEL (Tutorships)
Sampedro Perez, Luís (Co-tutorships)

Court
FERNANDEZ ESCRIBANO, JOSE ANGEL (Chairman)
BASELGA FRAGA, ANDRES (Secretary)
ROMERO BUJAN, MARIA INMACULADA (Member)

Summary
The aim of this study was to analyse long-term changes (2001-2023) in the structure of a passerine bird community, both during wintering and breeding, in a reedbed habitat at the Anllóns river estuary (A Coruña, NW Spain) based on ringing data. For the wintering community we expected a priori a change in the origin of the birds (with a lower representation of birds from higher latitudes) within the context of modern warming. For this purpose, the 7 species with the most complete information were selected and the variation over time in mean size (and variance) of wing chord, eighth primary (P8), tarsus and wing/tarsus ratio were studied. For the breeding community, a change in composition caused by the general increase in Sus scrofa wild boar populations linked to the abandonment of the rural world was initially expected. To test this hypothesis, temporal changes in the Shannon index and variation in the relative abundances of the 9 breeding species were analysed. There was no evidence of change in the origin of birds in any of the species selected to test the first hypothesis, using body size as a proxy. In the case of the second hypothesis, the Shannon index remained roughly constant over time and relative community abundances also did not follow a consistent temporal pattern. We conclude that, contrary to initial expectations, both communities (wintering and breeding) have hardly changed over the 22-year study period. Such constancy suggests a lack of effect of climate warming in recent decades and points to the absence of substantial environmental changes in the estuary during the breeding period. The profound ecological changes associated with the abandonment of the countryside in recent decades do not seem to have affected the study area, probably because cultivation ceased more than 40 years ago, judging by the available aerial images from the 20th century, and plant succession is at an advanced stage. Wild boars do not seem to have influenced the breeding community as these birds do not breed strictly on the ground, although in some cases they nest close to the ground.

Direction
MARTÍNEZ ABRAÍN, ALEJANDRO (Tutorships)
Maestro Saavedra, Miguel Ángel (Co-tutorships)

Court
FERNANDEZ ESCRIBANO, JOSE ANGEL (Chairman)
BASELGA FRAGA, ANDRES (Secretary)
ROMERO BUJAN, MARIA INMACULADA (Member)

Summary
As forested habitats in Galicia have developed over the past decades towards a rise of plantations for production purposes, different articles have addressed the topic of the effect of native forested habitats and plantations on biodiversity. Nevertheless, there has been little attention towards mixed habitats, comprising of a mixture of autochthonous and alien species. This study analyses the differences between species abundance, richness and composition across a range of four types of forested habitats: eucalyptus globulus plantations (EP), oak forests (CP, dominated by Quercus robur), and mixed forested habitats: oak forests with dispersed eucalyptus (CM) and eucalyptus plantations with dispersed oaks (EM). To carry out this study, bird vocalizations were registered with audio recorders throughout 32 sites, 8 sites for each type of habitat, at different moments during the day. From the samples collected, the number and duration of the vocalizations were gathered for each site as a measure of species abundance, and species were identified from each recording to obtain values of species richness and species composition for each site. After collecting the data, different statistical analyses were made for studying species abundance and richness (ANOVA, Fisher’s test and Tukey’s test), rarefaction curves and Chao2 indicator were used, and different analyses were made to study species composition (ANOSIM, NMDS and CDA). These analyses revealed that the habitat has a significant effect on species richness, number of vocalizations and species composition, but not on the duration of vocalizations. Mixed formations, CM and EM, had the highest abundance and highest alpha richness, but these values aren’t significantly different compared to oak forests. Nevertheless, there are significant differences between EP and the other habitats (with all of them or only with CM and EM, depending on the statistical analysis used). EP had the lowest abundance and lowest alpha richness, although its total richness wasn’t the lowest. Moreover, EP has the biggest difference in species composition compared to the rest of the habitats. It has species related to shrubs and adapted to human disturbed habitats, and it shows lower relative frequence of specialist and generalist forest bird species. The surprising capacity of mixed forested habitats to harbour bird biodiversity shown in this study, invites to reflect upon their effect on regional biodiversity conservation and on the implications these results have for forest management, when knowing that eucalypts have proven to have negative effects on ecosystems as they behave as an invasive species in Southern Europe. Results showing significant improvement of bird communities in eucalypt plantations and mixed habitats encourage to aim forest management measures in that direction, which could in turn have a considerable effect on biodiversity on these plantations, reducing its negative impact significantly. Future research can focus on improving the actual knowledge on mixed forested habitats in Galicia, studying their effects on other taxonomic groups.

Direction
Calviño Cancela, María (Tutorships)
Martín Herrero, Julio (Co-tutorships)

Court
FERNANDEZ ESCRIBANO, JOSE ANGEL (Chairman)
BASELGA FRAGA, ANDRES (Secretary)
ROMERO BUJAN, MARIA INMACULADA (Member)

Summary
Dryopteris guanchica and Dryopteris aemula are two relict pteridophyte species associated with humid forests with oceanic influence. In order to understand the factors that determine their distribution, this work approaches the characteristics of their bioclimatic niche by means of ecological niche modeling (ENM) to infer their possible past distribution since the late Pleistocene as well as their future distribution in different climate change scenarios. At the same time, the ecological niche was studied in greater geographic detail by means of ecosystem function attributes (EFAs), to evaluate aspects related to the conservation of the species. The revision of herbarium material, used to incorporate territorial presences to the models, revealed, apart from numerous incorrect determinations, the existence of D. guanchica specimens with an atypical morphology, whose niche was analyzed independently. The results show that D. aemula has always had a wider distribution along the European Atlantic arc, while D. guanchica has a more restricted and fragmented distribution. The island of Madeira, the island of Tenerife in the Canary Islands archipelago and the northwest coast of the Iberian Peninsula emerge as key potential refuges in the history of the two species.Future projections show significant contractions in currently occupied areas. The combination of habitat suitability and connectivity analysis identified critical areas for conservation, linked to optimal thermophilic oak woodland habitat quality, supporting the expansion of current conservation areas (SCAs) to ensure the preservation of these threatened ferns. These results highlight the vulnerability of relict ferns to climate change and the need to integrate ENMs and EFAs to improve conservation strategies.

Direction
SERRANO PEREZ, LUIS MIGUEL (Tutorships)

Court
FERNANDEZ ESCRIBANO, JOSE ANGEL (Chairman)
BASELGA FRAGA, ANDRES (Secretary)
ROMERO BUJAN, MARIA INMACULADA (Member)