Saint Peter And Saint Paul Archipelago Research Articles

An equatorial mid-Atlantic Ocean archipelago as nursery area for the cookiecutter shark: Investigating foraging strategies of neonates through bite mark inferences.

This study delves into the foraging ecology of the cookiecutter shark (Isistius brasiliensis) in the Saint Peter and Saint Paul Archipelago (SPSPA), assessing bite marks on pelagic fishes collected between March and September 2018. Examination of 200 individuals from five species revealed the shark's predilection for targeting adult fish, ensuring efficient removal of energy-rich tissue layers. However, a notable exception is Thunnus albacares, preyed on predominantly during its juvenile stage, possibly due to vertical spatial segregation. Recent bites were pervasive across species, with wahoo displaying a distinctive pattern. Cookiecutter shark bites predominantly targeted the lateral body portion (>55%) except for yellowfin tuna, which exhibited a preference for the ventral region (95%). The estimated length distribution suggests the SPSPA as a potential nursery area for cookiecutter sharks. Bite mark positions and frequencies may be linked to fish behavior, swimming velocity, and fishing gear strategy, highlighting the complex interplay in pelagic ecosystems.

Genetic diversity of polychaete annelids from the Saint Peter and Saint Paul Archipelago, Equatorial Atlantic, with description of a new species

The Saint Peter and Saint Paul Archipelago (SPSPA) is located in the mid-equatorial Atlantic and represents a potentially important area for biodiversity research; however, its species diversity remains poorly characterized. Particularly, neglected groups such as invertebrates have not been thoroughly registered or described. For instance, no species inventory is provided for Annelida, the phylum to which segmented worms belong. This study represents the first polychaete species inventory from SPSPA, including genetic and morphological data. We have generated COI mtDNA and 16S rDNA sequences intended as DNA barcode to molecularly identify polychaete species via different methods. First, we used the Barcode of Life Database (BOLD) identification tool; second, we calculated genetic distances and performed maximum likelihood trees with selected sequences from the Genbank database. We found that most species identified from SPSPA are strictly distributed in the Atlantic Ocean. Our methods proved that the accuracy of molecular identification was limited by the shortage of the annelid data available in BOLD and Genbank. Additionally, we describe a new species named Syllis belmontensis sp. nov. Overall, these results can be important resources for comparative studies on the distribution and genetic diversity of polychaetes worldwide.

Occurrence of Leach’s Storm-petrel Hydrobates leucorhous near the Saint Peter and Saint Paul Archipelago, Brazil

Storm-petrels demonstrate complex spatial dynamics, with some species moving among continents. We report a sighting of a Leach’s Storm-petrel Hydrobates leucorhous, recorded on a scientific expedition near the Saint Peter and Saint Paul Archipelago (SPSPA), the smallest Brazilian oceanic islands. Our species identification was based on A) morphological characteristics (plumage pattern and pronounced forked tail), B) other records of this species surrounding the SPSPA, and C) tracking studies of the at-sea distribution of this species, especially that of North Atlantic populations that cross equatorial regions during their migration and non-breeding periods. This report comprises the second of two documented accounts of Leach’s Storm-petrel in SPSPA waters. These records highlight knowledge gaps in the spatial dynamics of seabird species, an increased understanding of which might provide novel insights into species biogeography.

Mapping of surface radiogenic heat production from in situ gamma spectrometry and chemical data of exhumed mantle peridotites at the St. Peter and St. Paul archipelago (equatorial Atlantic)

This work presents the first mapping of the radiogenic heat production (RHP) and the respective radiogenic heat flow (RHF) of the Saint Peter and Saint Paul Archipelago (SPSPA) located at 1°N in the Equatorial Atlantic Ocean. Using radiogenic heat producing elements (RPE) we inferred a radiogenic heat production ranging 0.08–0.68 μW/m3 (Median: 0.21 μW/m3 and Geometric mean: 0.25 μW/m3) by whole-rock chemical analysis and between 0.08 and 0.48 μW/m3 (Median: 0.19 μW/m3; Geometric mean: 0.19 μW/m3) by in situ Gamma radiation spectrometry. The mean of radiogenic heat production of mylonite rocks from SPSPA (0.22 μW/m3) is significantly higher than predicted values for ultramafic rocks as those largely outcropping in the SPSPA. This is probably due to the pervasive alteration of these rocks and the incorporation of little magma fractions during mylonitization. By converse, the average surface radiogenic heat flow (49.7 μW/m2) is lower than that predicted for the oceanic lithosphere, suggesting that the upper mantle contribution to the heat flow is also low in the SPSPA region. Based on the acquired data and the peculiar tectonics of the SPSPA we propose that the lithospheric mantle around the SPSPA area is colder than that surrounding the Equatorial Atlantic region.

Back from the dead? Not really. The tale of the Galapagos shark (Carcharhinus galapagensis) in a remote Brazilian archipelago

The Galapagos shark, Carcharhinus galapagensis (Snodgrass & Heller, 1905) is a large circumtropical species mostly found around oceanic islands. In Brazil, commercial fishing in the Saint Peter and Saint Paul Archipelago (SPSPA), located in the equatorial Mid-Atlantic Ridge, resulted in a drastic reduction in the number of carcharhinid sharks, and the once very abundant Galapagos shark was then considered locally extinct. In opposition to this premature conclusion, however, this study provides records of the species, as well as its abundance trends and patterns of distribution in the SPSPA from the period of supposed disappearance to nowadays. Results are based on fishermen interviews, video footage and catch data obtained during the shark monitoring program conducted in the archipelago from 2010 to 2019. Galapagos shark was the second most caught shark in SPSPA, showing that this species is not only still present but is also becoming again one of the most common shark species in the archipelago. No significant difference was observed in sex ratio and in the size frequency distribution of males and females. An apparent recovery of carcharhinid sharks was attested by all fishermen interviewed. This recovery was mainly noticed after the complete ban on elasmobranch fishing, in 2012, emphasizing the vulnerability of these species to fishing pressure. Further research on the biology, ecology, behavior, and distribution patterns of Galapagos sharks will greatly aid future decision-making regarding the management and conservation of the species, not only in SPSPA, but in all insular ecosystems.

Corrigendum to: Evidence of site fidelity and deep diving behaviour of scalloped hammerhead shark (Sphyrna lewini) around the Saint Peter and Saint Paul Archipelago, in the equatorial Mid-Atlantic ridge

Seven scalloped hammerhead sharks (Sphyrna lewini) were satellite tagged around the Saint Peter and Saint Paul Archipelago (SPSPA), located at the equatorial Mid-Atlantic ridge, to investigate their vertical and horizontal movements. All sharks remained in the surroundings of the SPSPA over the course of the 120-day monitoring period, suggesting a high degree of medium-term site fidelity. During this period, scalloped hammerhead sharks covered a wide extension of the water column, ranging from the mixed layer to the mesopelagic zone. All sharks remained in warm (>22°C) shallow layers most of the time, but also dove to depths greater than 150m, mostly at night, eventually reaching 728m (5.6°C) on two occasions. This study contributes important, novel information on the habitat use and movement patterns of scalloped hammerhead shark in Atlantic equatorial oceanic waters. It also highlights the potential of protecting key, large oceanic areas as a useful tool for the conservation of this endangered species.

Dancing with the devil: courtship behaviour, mating evidences and population structure of the Mobula tarapacana (Myliobatiformes: Mobulidae) in a remote archipelago in the Equatorial Mid-Atlantic Ocean

Abstract The present work aimed at studying the sicklefin devil ray (Mobula tarapacana) that aggregates seasonally in the Saint Peter and Saint Paul Archipelago (SPSPA). From December 2008 to June 2016, 827 rays were sighted through free diving visual census survey. From the total of the records, it was possible to identify the sex of 361 specimens, in which 215 were females and 146 were males. The disk width ranged from 2.40 m to 3.20 m with mean size of 2.60 m, for both males and females, indicating that the population is composed by sub-adults and adults. Using photo-identification of the pectoral-fins in the ventral side, 11 males and 44 females were identified and compared with each other, but no re-sight was detected. Recent mating scars were observed in males (n= 7) and females (n= 6), as well as courtship and pursuit behaviors, confirming that the SPSPA is an important area of aggregation and mating for M. tarapacana in the Atlantic Ocean.

BRUVS reveal locally extinct shark and the way for shark monitoring in Brazilian oceanic islands.

Here we present records of sharks obtained using baited remote underwater stereo-video systems (stereo-BRUVS) at two Brazilian oceanic islands. Fourteen of the 60 deployments recorded 19 sharks in Trindade Island. In Saint Peter and Saint Paul Archipelago (SPSPA), two pelagic and two demersal deployments recorded two and one shark, respectively, including the locally extinct Galapagos shark Carcharhinus galapagensis. Stereo-BRUVS should be considered as adjuncts to other non-invasive methods to monitor shark populations.

Incidence of anthropogenic material in Sula leucogaster nests in a distant archipelago of Brazil

Anthropogenic debris has been affecting fauna in different ways. We investigate the frequency of anthropogenic material in nests of a brown booby (Sula leucogaster) colony in the Saint Peter and Saint Paul Archipelago (SPSPA), Rio Grande do Norte, Brazil in February 2015 and November 2016. The items were classified according to type (threadlike plastic, sheet plastics, hard fragments, foamed synthetics and miscellaneous) and color. In 2015, a total of 30 anthropogenic items were found in 20.4% of the nests. In nests containing debris, miscellaneous items were found in 73.6% of nests. White/clear was the most common color, 52.6% of nests containing debris had items of this color. In 2016, 45 anthropogenic items were observed in 13.3% of the nests. Threadlike plastic was found in 59.2% of nests. Blue/purple was the most common color (55.5%). Even far from the Brazilian coast, the S. leucogaster colony has been affected by marine pollution.

Zooplankton biomass around marine protected islands in the tropical Atlantic Ocean

Zooplankton biomass (as wet weight) was studied around marine protected islands in the tropical Atlantic Ocean. The study was based on 96 zooplankton samples collected during a 3-year period; specifically, 2010 was considered a year of thermal stress, and 2012 and 2014 were considered years without thermal stress. The analysis showed that zooplankton biomass varied significantly among protected areas, where the smallest and most isolated archipelago among the tropical islands, Saint Peter and Saint Paul Archipelago (SPSP), had approximately twice the biomass of Fernando de Noronha Archipelago (FN) and three times that of Rocas Atoll (RA). The position of SPSP near the equatorial divergence zone, the seasonal occurrences of phytoplankton blooms east of the Equator, the contribution of the productive waters that SPSP receives from the African coast under the influence of the South Equatorial Current (SEC) system and the local upwelling effect induced by the presence of the island were considered to be the factors responsible for the high pelagic productivity in this remote archipelago. Differences between day and night were also recorded. The high nocturnal biomass was considered an effect of the capture of larger-sized animals, which are considered to be strong migrators. The lowest zooplankton biomass was recorded in 2010 and was considered an apparent effect of the high sea surface temperature observed in that year. However, the interaction between spatial and interannual factors showed that, in FN and SPSP, the zooplankton biomass was lower in the year under thermal stress (2010). In contrast, RA presented a higher biomass value in this period. We suggest that this increase in zooplankton biomass is the result of the contribution of autochthonous sources (e.g., as a consequence of local physical events, such as current wakes, recorded during this period at RA and responsible for the increase in local planktonic productivity) and allochthonous sources (e.g., organisms supplied by FN via the zonal current).

Evidence of site fidelity and deep diving behaviour of scalloped hammerhead shark (Sphyrna lewini) around the Saint Peter and Saint Paul Archipelago, in the equatorial Mid-Atlantic ridge

Seven scalloped hammerhead sharks (Sphyrna lewini) were satellite tagged around the Saint Peter and Saint Paul Archipelago (SPSPA), located at the equatorial Mid-Atlantic ridge, to investigate their vertical and horizontal movements. All sharks remained in the surroundings of the SPSPA over the course of the 120-day monitoring period, suggesting a high degree of medium-term site fidelity. During this period, scalloped hammerhead sharks covered a wide extension of the water column, ranging from the mixed layer to the mesopelagic zone. All sharks remained in warm (>22°C) shallow layers most of the time, but also dove to depths greater than 150m, mostly at night, eventually reaching 728m (5.6°C) on two occasions. This study contributes important, novel information on the habitat use and movement patterns of scalloped hammerhead shark in Atlantic equatorial oceanic waters. It also highlights the potential of protecting key, large oceanic areas as a useful tool for the conservation of this endangered species.

Seasonal aggregation and diel activity by the sicklefin devil ray Mobula tarapacana off a small, equatorial outcrop of the Mid-Atlantic Ridge.

The present study aimed to analyse occurrence patterns, relative abundance and habitat use by the sicklefin devil ray Mobula tarapacana in the Saint Peter and Saint Paul Archipelago (SPSPA), Brazil, located in the Mid-Atlantic Ridge. Sampling was conducted between December 2008 and December 2012 by surface surveys and tagging with conventional tags and acoustic transmitters. Mobula tarapacana were sighted in the SPSPA year round but the highest frequency of occurrence was observed from January to June, probably due to greater food availability during this season. However, M. tarapacana might also use the area for reproductive purposes based on evidence of mating behaviour. The residency period of tagged rays measured by three autonomous acoustic receivers deployed around SPSPA spanned from 1 to 74 days with most of the detections occurring during daytime. These results suggest that the SPSPA could be an ecologically-important aggregation area for M. tarapacana, possibly providing the species with a feeding or resting habitat while transiting in the equatorial Atlantic Ocean.

Earthquake Magnitude Relationships for the Saint Peter and Saint Paul Archipelago, Equatorial Atlantic

We have investigated several relationships between ML, M(NEIC) and Mw for the earthquakes locally recorded in the Saint Peter and Saint Paul Archipelago (SPSPA), Equatorial Atlantic. Because we only have one station in the area, we could not derive attenuation relations for events recorded at different distances at different stations. Our approach was then to compare our ML estimates with magnitudes reported by NEIC. This approach produced acceptable results particularly for epicentral distance smaller than 100 km. For distances greater that 100 km, there is a systematic increase in the residuals probable due to the lack of station correction and our inability to accurately estimate Q. We also investigate the Mw—M(NEIC) relationship. We find that Mw estimates using S-wave produce smaller residuals when compared with both M(NEIC). Finally, we also investigate the ML—Mw relationship and observe that given the data set we have, the 1:1 holds. We believe that the use of the present methodologies provide consistent magnitude estimates between all the magnitudes investigated that could be used to better assess seismic hazard in the region.

Microseismic noise in the Saint Peter and Saint Paul Archipelago, equatorial Atlantic

Microseismic noise, also known as ambient seismic noise, are continuous vibrations mostly composed of Rayleigh waves pervasively recorded in the mili Hertz to 1 Hz frequency range. Their precise source mechanisms are under investigations and related to atmospheric perturbations and ocean gravity waves. Our purpose is to show the behavior of the microseismic noise recorded in the Saint Peter and Saint Paul Archipelago (SPSPA) with respect to wind intensity and ocean waves height in this region, between the North and South Atlantic Ocean. We have recorded both primary microseisms (PM) 0.04–0.12 Hz and the secondary microseisms (SM) 0.12–0.4 Hz during almost four years (2012–2015) and we used frequency, temporal, spatial and statistical correlation analysis to do qualitative and quantitative analysis with respect to wind speed intensity and significant wave height for the same periods. The results indicate a good correlation between the PM and the SM noise in the region particularly during the winter in the Northern Hemisphere and a poor correlation during the summer. We have also shown that probably most of the PM are generated in the SPSPA itself. We note that the intensity of SM recorded in SPSPA appears to have a seasonal behavior with the summer and winter in the Northern Hemisphere, and seems to influence the correlation between the PM and the SM, suggesting that the sources of the PM and the SM are not related to the same atmospheric event and from different places. PM generation would occur near the SPSPA whilst the SM would have distant sources towards the North Atlantic.

Trophic role of demersal mesopredators on rocky reefs in an equatorial Atlantic Ocean island

The decrease in the number of sharks around Saint Peter and Saint Paul Archipelago (SPSPA) may impact food web structure. We investigated trophic relationships in the shallow rocky reefs of the SPSPA using stable isotopes and stomach contents with a particular focus on three abundant mesopredators: Caranx lugubris, Enchelycore nigricans and Muraena pavonina. Food web structure was described using samples of the most abundant basal resources, fishes and invertebrates, which were collected in April and October 2012. Individuals of the three focal species (n = 138: C. lugubris, n = 56; E. nigricans, n = 18; M. pavonina, n = 64) were collected during four expeditions to SPSPA (April and October of 2011 and 2012). Results suggest that this shallow water food web is supported by trophic pathways originating from benthic resources. Stable isotope data suggest potential competitive interactions between the whitespot moray and the other two mesopredators. Conversely, stomach content data suggest little niche overlap in the three focal species, but these data must be interpreted carefully because of the small sample sizes and restricted temporal sampling windows. All three mesopredators have a significant, albeit weak, relationship between body size and δ15N, suggesting ontogenetic diet shifts. These data contribute baseline information to assess shifts in food web structure that may stem from top predator decline in this unique ecosystem.

Seasonal-Dial Shifts of Ichthyoplankton Assemblages and Plastic Debris around an Equatorial Atlantic Archipelago

Seasonality was a stronger influence in the ichthyoplankton assemblages around the Saint Peter and Saint Paul Archipelago (SPSPA) than distance from the islands. Plastic debris were ubiquitous and although it presented diel trends, no other spatiotemporal patterns was showed. Larval Oxyporhamphus micropterus was the most important taxa (29.37% of the total catch), followed by Ceratoscopelus warmingii and Entomacrodus vomerianus. Exocoetidae eggs represented 41.01%. Mesopelagic fish larvae dominated the community. Myctophidae had the highest species richness (15). Four larval fish assemblages occured: (1) nighttime demersal/bathydemersal (Anguillidae, Congridae); (2) daytime mesopelagic/bathypelagic/epipelagic (Myctophidae, Cyclothone acclinidens); (3) daytime epipelagic (Exocoetidae, Coryphaena hippurus, Thunnus albacares) and (4) nighttime reef and demersal (Blennidae, Pomacentridae, Lutjanidae). The dry season (lower temperature, higher chlorophyll a and higher SW wind velocity) influenced the first two assemblages. The rainy season (higher temperatures and lower NW wind velocity) influenced the last two. Nighttime abundance of dominant species in the rainy season suggests diel vertical migration nearshore. Plastics were 2.12 times more abundant than the most abundant fish larvae. Comparable amounts of larvae and plastics in the water column increase the chances of interaction between these two compartments and might disturb the local marine food web and promote the transfer of microplastic from one habitat to another, especially when smaller taxa contaminated by ingested fragments are preyed by migratory animals such as marine birds and tuna. A study around the area concluded that at least a part of the plastic debris can have local source due to fishing activities. Small-scale oceanographic mechanisms such as the interaction between the topography and currents (SEC and EUC) seem to be responsible for the retention of fish eggs, fish larvae and plastics around SPSPA.

A Black Kite Milvus migrans on the Saint Peter and Saint Paul Archipelago, Brazil

he Black Kite Milvus migrans is a widespread migratory raptor found over much of the Old World. Vagrants have been widely recorded far from its main migratory routes. Here, we report the occurrence of a Black Kite in the Brazilian Saint Peter and Saint Paul Archipelago (SPSPA) in April/May 2014. The bird remained for 32 days in the SPSPA, disappearing at the end of the rainy season. It looked healthy for most of this period and was once seen preying on a seabird chick. We speculate that the species was likely drifted off course by SW tradewinds, which may be responsible for the displacement of several other Old World bird species to the archipelagos of the west equatorial Atlantic, located in the Intertropical Convergence Zone. On the northwest African coast, trade winds are tangent to the western European-west African migratory flyway, which is used by M. m. migrans in its seasonal movements between Europe and Africa. We cannot, however, rule out ship-assistance for all or part of its journey to the archipelago. This is the first record of a Black Kite in Brazilian territory, although the species remains unknown on the American mainland.

Insights about the genetic diversity and population structure of an offshore group of common bottlenose dolphins (Tursiops truncatus) in the Mid-Atlantic.

Although the genus Tursiops has a worldwide distribution and is globally well-studied, some dolphin populations continue to face high risks of decline. Hence, it is necessary to assess the genetic diversity and structure of this genus to properly assess its conservation status and to implement appropriate management actions. In Brazil, genetic studies on this group remain rare, particularly for populations inhabiting offshore waters. Saint Peter and Saint Paul Archipelago (SPSPA) is a small group of islands located in the Mid- Atlantic Ridge, where recent studies of the Tursiops truncatus group indicate that individuals are resident throughout the year around the archipelago, exhibiting considerable site fidelity. A previous study with this group indicated that the individuals form an isolated population. To test this hypothesis, and describe the genetic diversity of SPSPA individuals, we assessed 12 microsatellite loci and a portion of the mitochondrial control region. Bayesian analysis revealed that SPSPA bottlenose dolphins form a unique population. In a phylogeographic perspective, we found that individuals from SPSPA shared mtDNA haplotypes with inshore and offshore individuals from North Atlantic, suggesting that they are not currently isolated from their conspecifics. Mirroring mtDNA findings, microsatellite analysis revealed that most of the pairs of individuals sampled seem to be unrelated (83.8%) and no indication of inbreeding, what would be expected if a small population such as SPSPA was reproductively isolated.

Floristic composition of crustose coralline algae from the St. Peter and St. Paul Archipelago, a summit of the Mid-Atlantic Ridge

Crustose Coralline Algae (CCA) are important constituents of tropical coral reef environments throughout the world’s oceans, acting as structural reinforcement and recruitment cues. Despite their importance and their ubiquity, very little is known of the biodiversity of CCA in remote areas of the world’s oceans. On the Saint Peter and Saint Paul Archipelago (SPSPA), located in the central equatorial Atlantic Ocean, CCA occur abundantly in intertidal rock pools and the surrounding subtidal zones. This study represents the first attempt at detailing the CCA species composition for the archipelago along a depth interval between 0 to 70 m. Seven taxa of CCA were identified: Corallinaceae sp., Hydrolithon rupestre, Hydrolithon sp., Lithophyllum johansenii, Lithothamnion muelleri, Mesophyllum engelhartii, and Titanoderma pustulatum pustulatum. A decrease in CCA species richness and change in species composition was seen from shallow to deeper zones that can be explained by a significant reduction in temperature and photon irradiance observed bellow 30 m depth.

Copepod distribution and production in a Mid-Atlantic Ridge archipelago.

The Saint Peter and Saint Paul Archipelago (SPSPA) are located close to the Equator in the Atlantic Ocean. The aim of this study was to assess the spatial variations in the copepod community abundance, and the biomass and production patterns of the three most abundant calanoid species in the SPSPA. Plankton samples were collected with a 300 µm mesh size net along four transects (north, east, south and west of the SPSPA), with four stations plotted in each transect. All transects exhibited a tendency toward a decrease in copepod density with increasing distance from the SPSPA, statistically proved in the North. Density varied from 3.33 to 182.18 ind.m-3, and differences were also found between the first perimeter (first circular distance band) and the others. The total biomass varied from 15.25 to 524.50 10-3 mg C m-3 and production from 1.19 to 22.04 10-3 mg C m-3d-1. The biomass and production of Undinula vulgaris (Dana, 1849), Acrocalanus longicornis Giesbrecht, 1888 and Calocalanus pavo (Dana, 1849) showed differences between some transects. A trend of declining biodiversity and production with increasing distance from archipelago was observed, suggesting that even small features like the SPSPA can affect the copepod community in tropical oligotrophic oceanic areas.