Carlos Navarro-Barranco

Long-distance dispersal, low connectivity and molecular evidence of a new cryptic species in the obligate rafter Caprella andreae Mayer, 1890 (Crustacea: Amphipoda: Caprellidae)

The amphipod Caprella andreae Mayer, 1890 was recorded for the first time in Southern Iberian Peninsula (36°44′15″N, 3°59′38″W). This species is the only obligate rafter of the suborder Caprellidea and has been reported to attach not only to floating objects such as ropes or driftwoods but also to turtle carapaces. Mitochondrial and nuclear markers were used to examine dispersal capabilities and population genetic structure of C. andreae across seven localities in the Mediterranean and Atlantic Ocean collected from floating substrata with different dispersal patterns. The strong population differentiation with no haplotypes shared between populations suggests that C. andreae is quite faithful to the substratum on which it settles. In addition, the proportionally higher genetic diversity displayed in populations living on turtles as well as the presence of highly differentiated haplotypes in the same turtle population may be indicative that these populations survive longer, which could lead C. andreae to prefer turtles instead of floating objects to settle and disperse. Therefore, rafting on floating objects may be sporadic, and ocean currents would not be the most important factor shaping patterns of connectivity and population structure in this species. Furthermore, molecular phylogenetic analyses revealed the existence of a cryptic species whose estimates of genetic divergence are higher than those estimated between C. andreae and other congeneric species (e.g. Caprella dilatata and Caprella penantis). Discovery of cryptic species among widely distributed small marine invertebrates is quite common and, in this case, prompts for a more detailed phylogenetic analysis and taxonomic revision of genus Caprella. On the other hand, this study also means the first record of the gammarids Jassa cadetta and Elasmopus brasiliensis and the caprellid Caprella hirsuta on drifting objects.

Effects of light pollution on the emergent fauna of shallow marine ecosystems: Amphipods as a case study

Light pollution from coastal urban development is a widespread and increasing threat to biodiversity. Many amphipod species migrate between the benthos and the pelagic environment and light seems is a main ecological factor which regulates migration. We explore the effect of artificial lighting on amphipod assemblages using two kind of lights, LED and halogen, and control traps in shallow waters of the Great Barrier Reef. Both types of artificial light traps showed a significantly higher abundance of individuals for all species in comparison to control traps. LED lights showed a stronger effect over the amphipod assemblages, with these traps collecting a higher number of individuals and differing species composition, with some species showing a specific attraction to LED light. As emergent amphipods are a key ecological group in the shallow water environment, the impact of artificial light can affect the broader functioning of the ecosystem.

Amphipod community associated with invertebrate hosts in a Mediterranean marine cave

The present study explored the amphipod communities associated with the dominant host invertebrates inhabiting a marine cave of South Spain in order to describe their species composition and distribution patterns. Although they play a key role in the structure of mobile epifaunal communities inhabiting most rocky reef ecosystems, this component of marine caves communities has often been overlooked. Colonies of six sessile species were collected: Astroides calycularis, Parazoanthus axinellae, Pentapora fascialis, Aldeonella calveti, Filograna implexa, and Ircinia fasciculata. In each sample the mobile epifaunal community (mainly focusing on the amphipod group) was characterized, with Arthropoda and Amphipoda being the dominant phylum and order, respectively. Among amphipods, the gammarid Lembos websteri and the caprellids Phtisica marina and Pseudoprotella phasma were the most abundant species. The endangered coral Astroides calycularis showed the most distinctive amphipod community and multivariate analysis highlighted the existence of significant differences in the amphipod assemblages among invertebrate hosts in the cave. However, no host-specific species were found. Benthic hosts inside the cave are mainly used as a refuge by amphipods and all the sessile species studied seem to play an equivalent facilitation role. To what extent changes in the composition of sessile species may affect other associated species was also discussed.

Impoverished mobile epifaunal assemblages associated with the invasive macroalga Asparagopsis taxiformis in the Mediterranean Sea

There is an increasing concern about the ecosystem consequences of altering macroalgal assemblages. Many macrophytes are foundation species in coastal habitats, supporting much of the biodiversity of these ecosystems by providing essential resources such as food and habitat. The addition of invasive species strongly contributes to habitat modification, but the bottom-up impacts of non-native macroalgae on higher trophic levels remains difficult to predict. The main aim of this study was to evaluate the effects of the invasive macroalga Asparagopsis taxiformis on biodiversity by comparing the mobile macrofauna inhabiting this species to the dominant native species Halopteris scoparia. This is the first comprehensive study of the possible effects of this widespread invasive species on higher trophic levels. A hierarchical sampling design with two different spatial scales was conducted to explore the consistency of the patterns observed. Fifty-nine species belonging to superorder Peracarida were found, accounting 90% of all organisms. A. taxiformis hosted an impoverished epifaunal assemblage in comparison to that associated with the native seaweed, showing significantly lower values of diversity, abundance and number of epifaunal species across study locations. The structure of the associated macrofauna (both in terms of species composition, variability among samples and relative abundance of the species) was also different. Our results highlighted the strong influence of A. taxiformis in the resident community, with differences among the two macroalgae in all the parameters considered. Finally, our results also reflect a biotic homogenization of the epifaunal assemblages associated to A. taxiformis, a scarcely explored consequence of invasive processes in marine environments. Future studies exploring the cascading effects of the observed changes in the epifaunal assemblages would be necessary in order to estimate system responses to macroalgal invasions.

Habitat selection of intertidal caprellid amphipods in a changing scenario

Habitat selection is a complex process, dependent on numerous fluctuating conditions and key to species coexistence. In a changing global scenario, it will greatly determine the fate of marine organisms and hence is an important subject to be explored. The present study evaluates host specificity of two caprellid amphipod species, Caprella grandimana and Caprella takeuchii, dwelling on a rocky intertidal where the calcifying macroalgae Jania rubens and Ellisolandia elongata show opposite seasonal fluctuation patterns throughout the year. To avoid confounding preference with other factors, the substrate selection experimental design included both multiple choice and non-choice treatments. Macroalgal structure analyses using fractals and interstitial space index were included in the study, as substrate complexity is a main factor driving preference for epifauna. Caprella grandimana actively selected J. rubens, whereas C. takeuchii did not show any preference; both behaviours remaining consistent regardless of the original substrate. Preference for J. rubens is probably owed to its interstitial space and thalli characteristics, as the complexity analysis suggested, since these allow for better refuge against predators and a more suitable surface for grasping. Meanwhile, the plasticity of C. takeuchii seems to favor an ongoing taking over of its congener at the time of the year when J. rubens drops. We highlight the need for rigor when performing substrate selection experiments; the importance of including habitat selection lessons in conservation strategies and modelling studies dealing with global change; and the risk in generalizing results within the family or genus level, which is occasionally inadequate for understanding the functioning of the ecosystem as a whole.

Long-term dynamics in a soft-bottom amphipod community and the influence of the pelagic environment

The processes and patterns seen in coastal benthic communities can be strongly influenced by the overlying pelagic environmental conditions. Integrating long-term biological and environmental data (both benthic and pelagic) can give insight into the specific relationships between key benthic functional groups and natural temporal changes in the marine environment. The identity and abundance of amphipod species found at Station L4 (Western English Channel) were tracked for 7 years (2008-2014), whilst simultaneously, annual changes in phytoplankton biomass, water temperature, salinity and chlorophyll a concentration were also characterized. The main species were persistent and showed little variability along the study period. Overall, however, there were significant changes in the structure of the whole community between sampling times, highlighting the importance of less numerically-dominant species in driving temporal variability. Surprisingly, the current study did not detect a significant influence of the phytoplankton biomass on benthic amphipod dynamics. On the other hand, there was a clear and constant correlation between bottom water temperatures and amphipod abundance. This pattern is different from that observed in other detritivorous species at L4, highlighting the complexity of benthic-pelagic coupling and the high variability of the response to pelagic conditions among different groups. As a result of the biogeographic position of the Western English Channel, the key role of amphipods in benthic communities, the influence of the temperature in their populations dynamics, as well as the solid baseline provided here and in previous studies, the monitoring of long-term amphipod dynamics in the English Channel could be a valuable tool to evaluate the biological effect of climate change over marine benthic communities.