The Mollusca of Galicia Bank (NE Atlantic Ocean)

An illustrated checklist of the Mollusca of Galicia Bank, a large and deep seamount off the NW Iberian Peninsula, is provided. The studied material was collected in 8 samples of Seamount 1 cruise (1987), 7 samples of ECOMARG 0709 (2009) and 36 samples of BANGAL 0711 (2011), between 615 and 1768 m. A total of 212 species are known to occur at the Galicia Bank (1 Monoplacophora, 7 Solenogastres, 3 Polyplacophora, 132 Gastropoda, 54 Bivalvia, 6 Scaphopoda, and 9 Cephalopoda), 21 of which from previous studies only. Four species are described as new, 34 species are first record in Spanish waters and another 20 species first record for the Northern Spanish waters. Over 7500 specimens, representing 104 species, were collected alive, and 87 species were represented by empty shells only. Only 53 species were detected in both Seamount 1 and BANGAL 0711; most of the species are rare and more species can be expected if exploration is continued. There is a marked difference in species composition between the summit platform (615‒1000 m) and the deeper part below 1500 m, with some genera (e.g., Colus and Limopsis) represented by alternative species. Endemism, if any, is very low and most of the species are widespread.

Fast and Reliable Identification of Ammonia Phylotypes T1, T2 and T6 Using a Stereomicroscope: Implication for Large-Scale Ecological Surveys and Monitoring Programs

Among benthic foraminifera, the genus Ammonia is characterized by high morphological variability which makes it particularly challenging to recognize using traditional morphology-based taxonomy. Despite the joint efforts made by both molecular and morphological taxonomists, it is still hard to identify different phylotypes based on their morphology. A new method was developed recently to discriminate three NE Atlantic phylotypes of Ammonia (T1, T2, and T6). This method is based on two morphometrical parameters using scanning electron microscope (SEM) images (i.e., the average pore diameter and the elevation of sutures on the spiral side), resulting individuals being correctly assigned to their phylotype in more than 90% of cases. In this study, we assess the possibility of implementing these criteria using a stereomicroscope. Phylotype assignations by SEM and stereomicroscopic identifications are in accordance for 62.6% of the scrutinized foraminifera and increase up to 79.5% when only the phylotype T6 is considered. Though the stereomicroscopic identification of Ammonia phylotypes based on these two morphological parameters needs to be cross-validated using molecular tools, this approach noticeably allows the identification of an individual 3 to 7 times faster than using a SEM. The ratio between accuracy and efficiency, an issue that is also attributable to the use of the rose Bengal staining method, suggests prioritizing the use of stereomicroscope identifications in large foraminiferal surveys. Finally, in the context that Ammonia phylotype T6 potentially being an alien species in Europe, this method will help to quickly identify Ammonia phylotypes; hence contributing to monitor the presence of T6 in different regions and then, offering interesting research perspectives to assess the timing and/or the progression of the possible invasion.

Sharks, rays and chimaeras of the Seine and Unicorn seamounts (NE Atlantic Ocean)

Background Seamounts are underwater mountains which typically rise rather steeply at least several hundred meters above the deep-sea floor. These geological features interrupt water flow and hence may induce changes in the circulation of different water masses, in turn causing different physical and biological effects. For this reason, seamounts are biodiversity hotspots, housing a wide number of species, as is with the case of the Seine and Unicorn seamounts, which are a part of the Madeira-Tore seamount chain located between Portugal mainland, southwestern Europe and Madeira archipelago (NE Atlantic). Methods Fisheries independent surveys allowed the collection of Chondrichthyes specimens from the Seine and Unicorn seamounts. Individuals were caught over the course of two research cruises, first in 2004 and later in 2017, with species distribution ranging from the summit down to 2500 m of depth. Results Fifteen species belonging to 7 different taxonomical families were collected in the two surveyed areas. Two species were recorded for the first time and added to the checklist of the Seine seamount (Centrophorus granulosus and Somniosus rostratus), and three species for the Unicorn seamount (C. granulosus, Centroscymnus coelolepis and Centroselachus crepidater). Distribution and frequency of occurrence for the collected species were evaluated in relation to depth. Conclusions This work is a valuable contribution to the knowledge of seamount-associated fish fauna. Moreover, the checklist of sharks, rays and chimaeras was updated for the Seine and Unicorn seamounts, summing up 20 species.

Spatial and Temporal Variability in the Occurrence and Abundance of European Hake Larvae, Merluccius merluccius, on the Galician Shelf (NE Atlantic)

The European hake (Merluccius merluccius) is represented as one of the most valuable fisheries in the Galician shelf. We analyzed the distribution, abundance, and environmental conditions of the southern-stock European hake larvae from the Galician shelf during the two main spawning peaks, winter-spring and summer, based on the data from three ichthyoplankton surveys (March 2012, March 2017, and June 2017). A total of 395 larvae in March 2012, 121 in March 2017, and 69 in June 2017 were captured. The northeast section of the study area, close to Estaca de Bares, primarily between 100 and 200 m isobaths, had the highest presence of the European hake larvae in all surveys. Generalized additive models (GAMs) indicated that the occurrence of larvae was significantly different between the surveys and was associated negatively with the temperature, while the abundance of larvae was significantly different between sampling years and was the highest at a temperature around 13.36°C and at sea surface heights of about −0.48 m. Studies of the distribution of early life stages and their relation to external conditions are essential to the understanding of the complex process of recruitment, especially in the exploited species and in highly dynamic environments like the Galician shelf.

Arrival and proliferation of the invasive seaweed Rugulopteryx okamurae in NE Atlantic islands

The present study reports the recent occurrence and expansion of Rugulopteryx okamurae in the Azores archipelago (NE Atlantic). Morphological and molecular characters confirmed the species identification. Quick surveys around the island of São Miguel showed that it has successfully colonized the island and is quickly expanding. In some locations, R. okamurae is currently the dominant organism smothering all other benthic biota and posing a serious threat to the benthic ecosystems across the region. The species first record dates from 2019 near the main harbour of the island, suggesting that its introduction was driven by human-assisted transport, via boat ballast waters or adhered to ship hulls and likely originating from the Mediterranean populations that have been proliferating in recent years across the Strait of Gibraltar.