Planktonic Ctenophora of the Madeira archipelago (Northeastern Atlantic)

Ctenophores are fragile gelatinous organisms whose diversity and distribution are relatively unknown. For the first time, the occurrence of four planktonic species, namely Ocyropsis crystallina, Eurhamphaea vexilligera, Cestum veneris, and Beroe sp., was reported from Madeira archipelago waters (NE subtropical Atlantic). This report represents the northernmost records in the Eastern Atlantic Ocean for O. crystallina and E. vexilligera.

Revalidation and redescription of Serranus knysnaensis Gilchrist, 1904, (Perciformes: Serranidae) with a new distribution record

A southwestern Indian Ocean (SWIO) percoid fish Serranus knysnaensis Gilchrist, 1904, was long synonymised with the comber, Serranus cabrilla (Linnaeus, 1758), from the eastern Atlantic Ocean, Mediterranean and Black Sea. However, when the species was brought out of synonymy by Heemstra & Heemstra (2004), reasons for this decision were not given. This study aims to revalidate the present taxonomic status of S. knysnaensis using morphological and molecular assessments. The two species are distinguished by the number of circumpeduncular scales (26–34 in S. knysnaensis versus 34–38 in S. cabrilla) and total gill rakers (18–22 versus 22–24). Serranus knysnaensis is also distinct from S. novemcinctus Kner, 1864, the other SWIO species of Serranus, based on total gill raker counts (18–22 versus 31–35). Genetic analysis of mitochondrial DNA barcode (COI) sequences for 17 Serranus species revealed three closely-related monophyletic clusters corresponding to S. cabrilla, S. novemcinctus and S. knysnaensis that were supported (P <0.001) by species delimitation methods. Even though the genetic distances among the three species were the lowest in the genus (1.60−1.99%), these species may be ecomorphs or lineages that have only recently diverged from each other. These three species also have allopatric distributions and our morphological and molecular data thus confirm that S. knysnaensis is a valid species.

Distinctive morphological characteristics of Fucus guiryi (Fucales, Phaeophyceae) from Canary Islands, subtropical eastern Atlantic Ocean

The brown macroalgae in the order Fucales include foundation species on rocky habitats of temperate regions. This work focused on Fucus guiryi, a recently described species segregated from F. spiralis in a molecular basis. It inhabits the upper intertidal zone from the eastern North Atlantic to the subtropical Canary Islands, where is considered its southern limit. We examined morphology and anatomy of vegetative and reproductive structures of F. guiryi from the Canary Islands. Several distinctive characteristics in habit existed between F. guiryi and other species of the genus distributed northwards, such as length and width of stipe and branches, number of branches, and morphology and number of receptacles. Anatomical features reported here for the first time exhibited subtle differences with temperate F. vesiculosus, F. spiralis and F. serratus. The morphology and arrangement of medulla, cortex and meristoderm were also distinctive for F. guiryi. Mucilage in cellular interstitial spaces constitutes good evidence that explains the presence of F. guiryi at its warmest distribution limit in the Canary Islands.

AGE AND GROWTH OF THE BLUE SHARK PRIONACE GLAUCA IN THE EASTERN ATLANTIC OCEAN

In this study, 292 blue sharks Prionace glauca (Linnaeus, 1758) (from 151 to 305 cm total length, TL) were collected off western Africa in the eastern central Atlantic Ocean between 1980 and 1982. Vertebral sections of females specimens ranged from 175 to 300 cm and males specimens ranged from 166 to 312 cm TL were processed and analyzed for age and growth parameters. Growth band pairs (translucent and opaque bands) were counted on the images photographed from the stained whole vertebrae using digital microscope called Digi Scope II. The band pairs after the birthmark were counted from 3 to 12 for males and from 4 to 13 for females. Growth parameters were derived using the Von Bertalanffy growth function (VBGF) based on FISAT and solver solution Microsoft excel and Ford Wall-Ford. VBGF was that which best fit the data. Parameters derived from the combination of observed and back-calculated lengths, K = 0.1, L_∞ = 386.4 cm and t_0 = −1.35 year for males and K = 0.12 year -1, L_∞= 355 cm and t_0 = –1.02 year for females were considered to best describe growth. The longevity was estimated to be at least 23.7 and 28.3 years for females and males respectively. The natural mortality rate was estimated to be 0.15 year - 1 and 0.18 year -1 for males and females respectively.

Seasonal cycling of zinc and cobalt in the south-eastern Atlantic along the GEOTRACES GA10 section

We report the distributions and stoichiometry of dissolved zinc (dZn) and cobalt (dCo) in sub-tropical and sub-Antarctic waters of the south-eastern Atlantic Ocean during austral spring 2010 and summer 2011/2012. In sub-tropical surface waters, mixed-layer dZn and dCo concentrations during early spring were 1.60 ± 2.58 nM and 30 ± 11 pM, respectively, compared with summer values of 0.14 ± 0.08 nM and 24 ± 6 pM. The elevated spring dZn concentrations resulted from an apparent offshore transport of elevated dZn at depths between 20–55 m, derived from the Agulhas Bank. In contrast, open-ocean sub-Antarctic surface waters displayed largely consistent inter-seasonal mixed-layer dZn and dCo concentrations of 0.10 ± 0.07 nM and 11 ± 5 pM, respectively. Trace metal stoichiometry, calculated from concentration inventories, suggests a greater overall removal for dZn relative to dCo in the upper water column of the south-eastern Atlantic, with inter-seasonally decreasing dZn / dCo inventory ratios of 19–5 and 13–7 mol mol−1 for sub-tropical surface water and sub-Antarctic surface water, respectively. In this paper, we investigate how the seasonal influences of external input and phytoplankton succession may relate to the distribution of dZn and dCo and variation in dZn / dCo stoichiometry across these two distinct ecological regimes in the south-eastern Atlantic.

Predicted Shifts in the Distributions of Atlantic Reef-Building Corals in the Face of Climate Change

Many species drive the diversity of ecosystems by adding structural complexity to the environment. In coral reefs, stony corals act as habitat-forming species, increasing niche availability for other organisms. Some coral species play key roles as reef builders due to their abundance or morpho-functional characteristics. Thus, changes in the distributions of these species can entail cascading effects in entire ecosystems. With climate change, many coral species are experiencing shifts in their distributions, threatening the preservation of coral reefs. Here, we projected the current and future distributions of three key reef builders of the Atlantic (Mussismilia hispida, Montastraea cavernosa, and the Siderastrea complex) under three relative concentration pathway scenarios: the most optimistic, the most pessimistic and one moderate scenario (RCP2.6, 4.5, and 8.5). Our models revealed that all the above species will undergo habitat loss in the future (2100) in the most pessimistic scenario, although new areas could become suitable, including regions in the eastern Atlantic Ocean. Additionally, when considering only its actual range of occurrence, M. hispida will lose habitats under all future scenarios. Moreover, in some regions of both the Tropical Northwestern Atlantic (TNA) and the Brazilian coast, these three species could disappear, with detrimental consequences for the associated communities. We highlight the need for an urgent change of course to guarantee functional reefs in the Atlantic in the future.

Raja mauritaniensis: a replacement name for Raja africana Capapé, 1977 (Rajiformes: Rajidae), a junior homonym of Raja africana Bloch & Schneider, 1801 (Myliobatiformes: Dasyatidae)

Raja africana Capapé, 1977 is a primary junior synonym of Raja africana Bloch & Schneider, 1801 and therefore permanently invalid (International Code of Zoological Nomenclature, article 57.2) and must be replaced. Raja africana Bloch & Schneider, 1801 was first described by Bloch & Schneider (1801: 367), based on a specimen from Guinea, West Africa (eastern Atlantic Ocean). The unique holotype is extant in the Zoologisches Museum of the Humboldt University, Berlin (ZMB 7837, a partial dry skin). The species was treated as valid as Urogymnus africanus (Bloch & Schneider 1801) by Compagno & Roberts (1984: 285), but later synonymized with Urogymnus asperrimus (Bloch & Schneider 1801) in the subfamily Urogymninae of the family Dasyatidae (Myliobatiformes) by Compagno (1986: 141), Capapé & Desoutter (1990: 63) and Séret (2016: 1418). It is widespread in the eastern Atlantic, Red Sea and Indo–West Pacific.