Olivia Dabney

Marine habitats and ecosystems are increasingly being impacted by global climate change and the global spread of captive breeding. In this study, we focused on five typical Trachinotus species (Trachinotus anak, Trachinotus blochii, Trachinotus mookalee, Trachinotus goreenisi, Trachinotus ovatus) as research subjects. We utilized species distribution models and ecological niche models to predict the present and future potential distribution of these species, as well as to assess ecological niche overlap and evaluate the early warning of invasion by Trachinotus species. T. ovatus stands out with its broad distribution range and high adaptability to different environments. It occupies 1.114% of medium-high suitable areas, spanning 100,147 km2. Our predictions also suggest that T. ovatus would undergo a significant expansion (approximately 55% of the total area) under both past and future environmental scenarios, demonstrating a higher tolerance and adaptability to changes in ambient temperatures. It can be discerned that T. ovatus exhibits strong environmental adaptability, which may potentially lead to biological invasion along the southeastern coast of China. The T. anak, on the other hand, showed a higher expansion trend under high carbon dioxide concentrations (RCP8.5), indicating a certain convergence with carbon dioxide concentration. Our models showed that under future climatic conditions, T. ovatus would become the dominant species, with increased competition with T. mookalee and decreased competition with T. goreenisi, T. mookalee, and T. anak. Based on our findings and the net-pen culture mode of T. ovatus, we identified the hotspot habitat of T. ovatus to be located in the Indo-Pacific convergence zone. However, there is a possibility of an expansion trend towards the southeast coast of China in the future. Therefore, it is crucial to provide an early warning for the potential biological invasion of T. ovatus.

Recent advances in genomics are an essential contributor to the assessment of fish stocks by providing a fine-scale identification of the species' genetic boundaries. The blackspot seabream, Pagellus bogaraveo, is a commercial sparid distributed across the northeast (NE) Atlantic and the Mediterranean. Within the NE Atlantic, three P. bogaraveo stocks are currently defined: Azores; Atlantic Iberian waters; Celtic Sea and the Bay of Biscay. We used a genotyping-by-sequencing (GBS) approach to better define the spatial scale at which the species occurs in the NE Atlantic. Our findings revealed the existence of an additional genetic cluster in the eastern Atlantic (Gulf of Cádiz) that was not identified in previous studies based on mitochondrial DNA or microsatellite data. The combined effect of ocean circulation patterns, complex bathymetry and the existence of local upwelling may play an important role on the retention of blackspot seabream larvae and adults, providing an explanation for the genetic differentiation between the specimens caught off the Gulf of Cádiz and Peniche (Portugal). Results presented here revealed hidden intra-specific genetic differentiation and can inform a finer-scale sampling to determine the new stock boundaries in the Atlantic Iberian coasts.

Unraveling the effects of latitudinal and elevational gradients on species distribution has been a central topic in biogeography for decades. However, few studies have evaluated the effects of the interaction between both gradients on species distributions. The main goal of this study was to evaluate the interaction of latitude and elevation in a freshwater context using a regional dataset of Iberian inland fish species. For this purpose, we compiled occurrence data for the 15 most widespread (i.e., present in multiple basins) Iberian fishes. We used generalized linear models including elevation, latitude, their quadratic terms, the interaction between the two gradients, and the basin as sources of variation. Results revealed contrasting species-specific distribution patterns with differing importance of the elevation and latitudinal gradients. Latitude was particularly important in explaining the distribution patterns of Salmo trutta, while the distribution of diadromous species and invasive Gambusia holbrooki or Lepomis gibbosus was mainly mediated by elevation. We detected significant interaction between elevation and latitude for 11 out of the 15 studied species. Consequently, Iberian fish species occupy different elevational niche positions depending on latitude. For example, Salmo trutta and Oncorhynchus mykiss occupy intermediate and even lower reaches in the northernmost areas. However, their occurrence probability decreases at lower latitudes, despite they can occur in elevated areas in these regions (e.g., Baetic Mountains). Finally, we discuss the potential effects of climate change on distribution patterns of the Iberian fish species studied.

The Wallacean shortfall refers to the knowledge gap in biodiversity distributions. There is still limited knowledge for freshwater fish species despite the importance of focusing conservation efforts towards this group due to their alarming extinction risk and the increasing human pressure on freshwater ecosystems. Here, we addressed the Wallacean shortfall for freshwater fish faunas across Europe by using the completeness indicator derived from species accumulation curves to quantify the fish sampling efforts. The multiple potential drivers of completeness that were previously related to the sampling efforts for other species (i.e., population density, nature reserves, or distance to cities) were tested using a 10 × 10 km2 grid resolution, as well as environmental (e.g., climatic) factors. Our results suggested that although there was an overall spatial pattern at the European level, the completeness was highly country-dependent. Accessibility parameters explained the sampling efforts, as for other taxa. Likewise, climate factors were related to survey completeness, possibly pointing to the river conditions required for fish sampling. The survey effort map we provide can be used to optimize future sampling, aiming at filling the data gaps in undersampled regions like the eastern European countries, as well as to account for the current bias in any ecological modeling using such data, with important implications for conservation and management.

Aim Unravelling the ecological and historical factors that underlie species distributions has challenged ecologists for a long time. Thus, our objective is to understand the role of environmental variables explaining the distribution of three major eco-evolutionary groups of inland fishes (Darlington's divisions: primary, i.e. strict freshwater; secondary, i.e. salt-tolerant; and peripheral, i.e. diadromous and marine origin), and how these variables are related to fish traits. Location Iberian Peninsula. Taxon 51 native and 17 alien inland fish species from the Iberian Peninsula. Methods We modelled distributions of the most common inland fish species across the Iberian Peninsula to compare the importance of different predictors among the three Darlington's divisions and between native and alien species. To explore the importance of specific environmental variables in determining the distribution of different traits of inland fish, variable importances obtained from species distribution models were subjected to a redundancy analysis. Results Darlington's divisions differ significantly in salinity tolerance, in distribution overlap, in the importance of distribution predictors and associated life-history traits. Topographic and climatic variables were generally more important than land use and anthropogenic factors in explaining fish distributions. We found significant differences in the importance of variables explaining the distribution of native vs. alien species and especially among Darlington's divisions. River basin was most important for primary native and many alien species. Increasing mean temperature and damming were positively associated with the presence of tolerant, large-bodied and warm-water alien species from more hydrologically stable habitats. Main conclusions Despite marked differences in the distribution patterns of native and alien species, evolutionary and introduction histories as well as seawater tolerance are central factors explaining the current distribution of inland fishes. Darlington's divisions proved useful for addressing ecological and biogeographical questions at broader spatial scales.

Fisheries and aquaculture are facing many challenges worldwide, especially adaptation to climate change. Investigating future distributional changes of largely harvested species has become an extensive research topic, aiming at providing realistic ecological scenarios on which to build management measures, to help fisheries and aquaculture adapt to future climate-driven changes. Here, we use an ensemble modelling approach to estimate the contemporary and future distributional range of eight demersal fish species of high economic value in the Mediterranean Sea. We identify a cardinal influence of (i) temperature on fish species distributions, all being shaped by yearly mean and seasonality in sea bottom temperature, and (ii) the primary production. By assessing the effects of changes in future climate conditions under three Representative Concentration Pathway (RCP2.6, RCP4.5 and RCP8.5) scenarios over three periods of the twenty-first century, we project a contraction of the distributional range of the eight species in the Mediterranean Sea, with a general biogeographical displacement towards the North European coasts. This will help anticipating changes in future catch potential in a warmer world, which is expected to have substantial economic consequences for Mediterranean fisheries.

Understanding what determines range expansion or extinction is crucial to predict the success of biological invaders. We tackled this long-standing question from an unparalleled perspective using the failed expansions in Littorina saxatilis and investigated its present and past habitat suitability in Europe through Ecological Niche Modelling. This intertidal snail is a typically successful Atlantic colonizer and the earliest confirmed alien species in the Mediterranean Sea, where, however, it failed to thrive despite its high dispersal ability and adaptability. We explored the environmental constraints affecting its biogeography, identified potential glacial refugia in Europe that fuelled its post-glacial colonisations and tested whether the current gaps in its distribution are linked to local ecological features. Our results suggested that L. saxatilis is unlikely to be a glacial relict in the Mediterranean basin. Multiple Atlantic glacial refugia occurred in the Last Glacial Maximum, and abiotic environmental features such as salinity and water temperature have influenced the past and current distributions of this snail and limited its invasion of the Mediterranean Sea. The snail showed a significant overlap in geographic space and ecological niche with Carcinus maenas , the Atlantic predator, but distinct from Pachygrapsus marmoratus , the Mediterranean predator, further pointing to Atlantic-like habitat requirements for this species. Abiotic constrains during introduction rather than dispersal abilities have shaped the past and current range of L. saxatilis and help explaining why some invasions have not been successful. Our findings contribute to clarifying the processes constraining or facilitating shifts in species’ distributions and biological invasions.

The ongoing contemporary biodiversity crisis may result in much of ocean’s biodiversity to be lost or deeply modified without even being known. As the climate and anthropogenic-related impacts on marine systems accelerate, biodiversity knowledge integration is urgently required to evaluate and monit…

Amphipod crustaceans are an essential component of tropical marine biodiversity. However, their distribution and biogeography have not been analysed in one of the world’s largest tropical countries nested in the Coral Triangle, Indonesia. We collected and identified amphipod crustaceans from eight s…

Background Understanding the interplay between climate and current and historical factors shaping genetic diversity is pivotal to infer changes in marine species range and communities’ composition. A phylogeographical break between the Atlantic and the Mediterranean has been documented for several m…