Arquipelago - Life and Marine Sciences

Apletodon gabonensis, a new species of clingfish (Teleostei: Gobiesocidae) from Gabon, eastern Atlantic Ocean

2020-05-07T10:09:00+01:00

The clingfish Apletodon gabonensis sp. nov. is described on the basis of seven specimens and colour photographs from Gabon, eastern Atlantic Ocean. The species is small, apparently not exceeding 20 mm total length; it is characterized by having 5 dorsal-fin rays, 4-5 anal-fin rays, 25-27 pectoral-fin rays, head width in males 2.6-4.7 in SL, anus in males with urogenital papilla present but not pronounced; snout long, broad, anteriorly truncate in male, narrower and rather pointed in female; preorbital length 1.8-3.8 in head length; conspicuous maxillary barbel absent in both sexes; disc with 10-12 rows of papillae in region A, 5 rows of papillae in region B, and 5-7 rows of papillae in region C. The new species is compared with the other species of the genus; a key to the males of the 6 known species of the eastern Atlantic genus Apletodon is presented.

Snake eels (Ophichthidae) of the remote St. Peter and St. Paul’s Archipelago (Equatorial Atlantic): Museum records after 37 years of shelf life

2020-05-07T10:09:03+01:00

Despite of its major zoogeographical interest, the biological diversity of central Atlantic oceanic islands are still poorly known because of its remoteness. Incomplete species inventories are a hindrance to macroecology and conservation because knowledge on species distribution are important for identifying patterns and processes in biodiversity and for conservation planning. Records of the snake-eel family Ophichthidae for the St. Peter and St. Paul’s Archipelago, Brazil, are presented for the first time after revision of material collected and deposited in a museum collection 37 yrs ago. Specimens of Apterichtus kendalli and Herpetoichthys regius were collected using rotenone on sand bottoms and one Myrichthys sp. was observed and photographed swimming over a rocky reef. Remarkably, these species were not seen or collected in the St. Peter and St. Paul’s Archipelago ever since despite the substantial increase of biological expeditions over the past two decades, suggesting that the unjustified rotenone sampling prohibition in Brazil is hindering advancement of the nation’s biological diversity knowledge.

First record of the Sculptured Mitten Lobster Parribacus antarcticus (Crustacea, Decapoda, Scyllaridae) from the Cabo Verde Islands (eastern Atlantic)

2020-05-07T10:08:58+01:00

The lobster genus Parribacus contains six living and one fossil species (Holthuis 1991; Chan 2010; Nyborg & Garassino 2017). In the Atlantic Ocean, only one living species is known, Parribacus antarcticus (Lund, 1793); it has been recorded in the western Atlantic from Florida to Brazil and recently also from the mid-Atlantic island of Ascension (Brown et al. 2016). It is nocturnal and is often found hiding in crevices during daytime (Holthuis 1991). We here note the presence of Parribacus antarcticus at the Cabo Verde Islands, the first record of the species from the eastern Atlantic.

The polychaete Lygdamis wirtzi at Ascension and St Helena Islands (Annelida, Polychaeta, Sabellariidae)

2020-05-07T10:08:55+01:00

Little is known about the polychaete fauna of the two mid-Atlantic Islands, Ascension and St Helena. Baird (1864), Monro (1930), and Hartmann-Schröder (1992) documented the polychaetes from Ascension Island while Day (1946) reported polychaetes from St Helena Island. Lastly, Yáñez-Rivera & Brown (2015) reported on Hermodice and Eurythoe from both Ascension and St Helena Islands. We do not know any other publications on polychaetes for these two remote islands.

A first assessment of operator compliance and dolphin behavioural responses during swim-with-dolphin programs for three species of Delphinids in the Azores

2020-05-07T10:08:52+01:00

The popularity of swim-with wild dolphin programs around the world is fast growing, with the studies required to investigate their impact lagging behind. In the Azores, species targeted include the short-beaked common (Delphinus delphis), the bottlenose (Tursiops truncatus) and the Atlantic spotted dolphin (Stenella frontalis). To evaluate the effects of this activity on local dolphin populations, and thus provide support for management decisions, dolphin response data were collected onboard commercial boats off São Miguel Island between 2013 and 2015. All three species revealed high degree of neutral and avoidance behaviours, and very low approach rates. Tursiops showed higher frequency of neutral responses than Delphinus, while Stenella both avoided and approached more frequently than the other species. When boats intersected the path of dolphin groups, avoidance responses were more likely and the duration of swims was shorter. Swims were also shorter when animals were resting and travelling, and when groups were smaller. The operators generally complied with the legislation, except in respect to the number of swim attempts per dolphin group, which was higher than the legal maximum. Improvement of the current legislation and concurrent reinforcement of controls is essential to avoid detrimental long-term effects of this activity on dolphin populations in the Azores.

The marine macroalgae of Cabo Verde archipelago: an updated checklist

2020-05-07T10:08:50+01:00

An updated list of the names of the marine macroalgae of Cabo Verde, an archipelago of ten volcanic islands in the central Atlantic Ocean, is presented based on existing reports, and includes the addition of 36 species. The checklist comprises a total of 372 species names, of which 68 are brown algae (Ochrophyta), 238 are red algae (Rhodophyta) and 66 green algae (Chlorophyta). New distribution records reveal the existence of 10 putative endemic species for Cabo Verde islands, nine species that are geographically restricted to the Macaronesia, five species that are restricted to Cabo Verde islands and the nearby Tropical Western African coast, and five species known to occur only in the Maraconesian Islands and Tropical West Africa. Two species, previously considered invalid names, are here validly published as Colaconema naumannii comb. nov. and Sebdenia canariensis sp. nov.

Hawksbill (Eretmochelys imbricata) and Green Turtle (Chelonia mydas) Nesting and Beach Selection at Príncipe Island, West Africa

2020-05-07T10:08:48+01:00

Hawksbills (Eretmochelys imbricata) and green turtles (Chelonia mydas) are the predominant nesting sea turtle species on the beaches of Príncipe Island in the Gulf of Guinea. The extent of nesting has been largely unknown, but such information is essential for management and conservation. Our study is the first island-wide nesting assessment. Results from the survey, conducted from 1 December 2009 to 18 January 2010 (during peak nesting season), show that the potential suitable nesting area (10 km) is scattered around the island’s 50 beaches. Sea turtles nested on 32 of the beaches (hawksbills, 20; green turtles, 28) and used 7.5 km of the suitable nesting habitat (hawksbills, 5.8 km; green turtles, 7.0 km). We estimated that 101 (95% CI = 86–118) clutches were deposited by 17-29 hawksbills and 1088 (95% CI = 999–1245) clutches were deposited by 166-429 green turtles on Príncipe from November 2009 to February 2010 (nesting season). Long-term green turtle nest count data collected from 2007/08 to 2015/16 suggest a positive trend. Analyses of clutch densities in relation to beach characteristics suggested that both species preferred areas where human presence is lower, which coincided with the most sheltered areas. These findings should be used to inform coastal planning and minimize impacts on nesting beaches, as Príncipe is currently targeted for tourism development. Overall, results highlight that Príncipe beaches are very important for the conservation of West African hawksbill and green turtle populations.

First record of an Odontaspidid shark in Ascension Island waters

2020-05-07T10:08:44+01:00

The occurrence of the poorly understood shark species Odontapsis ferox is reported at an oceanic seamount in the central south Atlantic, within the Exclusive Economic Zone of Ascension Island. The presence of the species at this location is confirmed by the discovery of a tooth embedded in scientific equipment, and footage of at least one animal on autonomous underwater video. The new record of this shark species at this location demonstrates the knowledge gaps which still exist at many remote, oceanic structures and their candidacy for status as important conservation areas.

Short term effects of irradiance on the growth of Pterocladiella capillacea (Gelidiales, Rhodophyta)

2020-05-07T10:08:41+01:00

Pterocladiella capillacea has been economically exploited for agar extraction in the Azores for many years. Harvesting dropped to a full stop in the early 1990s due to a population collapse, but restarted in 2013. Since then it has been intensively harvested and overexploitation must be prevented, with both sustainable harvesting and effective cultivation practices. This study represents the first attempt to determine optimal conditions for P. capillacea production in the Azores, and evaluates its vegetative growth in two experiments using von Stosch’s medium designed to test entire thallus and tips portions response to different irradiances (30, 70 and 150 μmol photons m^-2 s^-1). The best relative growth rate (RGR) was recorded at 150 μmol photons m⁻² s⁻¹ for the entire thalli and tips after two-weeks and three-weeks, respectively, indicating that an acclimation period is necessary to assure the growth of this alga under experimental conditions. Higher RGR was obtained at higher irradiance (3.98 ± 2.10% fm day^-1), but overall, growth rates were low or negative. Epiphytes were a serious problem towards the end of the entire thallus experiments, where Feldmannia irregularis proliferate at all irradiances. Future cultivation approaches complemented with other relevant environmental factors (e.g. pH, photoperiod, salinity), are recommended.