Houtman Abrolhos Research Articles

Wind mapping using the mesoscale WRF model in a tropical region of Brazil

This study details an evaluation of the onshore and offshore wind speed field in the state of Bahia, northeastern Brazil, using the WRF (Weather Research and Forecasting) mesoscale model, version 4.0. The simulations were run for a period of five years—between 2015 and 2020—with a horizontal resolution of 3 km, and were compared with data from 41 automatic surface stations for the onshore case. For the offshore case, data from a surface station located in the Abrolhos Archipelago were used. The winter period presents higher values of wind speed for the onshore region (9–14 m/s), and the northern and southwestern regions of the state stand out for the generation of wind energy. In the offshore case, spring presents the highest averages for wind speed (7–8 m/s), followed by the summer season, highlighting the maritime coast in the extreme south of the state (7–10 m/s). Furthermore, the nocturnal wind regime is more intense than the daytime one, indicating a great complementarity with solar energy. The year 2017 had the highest average values of wind speed in the region, being considered one of the warmest years without the influence of the El Nino phenomenon recorded globally since 1850. The hourly averages of onshore and offshore winds for the state of Bahia demonstrated the great wind potential of the region, with high and medium speeds at altitude, which were in accordance with the minimum attractiveness thresholds for investments in wind energy generation.

Morphostructure, emplacement and duration of the Abrolhos Magmatic Province: A geophysical analysis of the largest post-breakup magmatism of the South-Eastern Brazilian margin

The Abrolhos Magmatic Province (AMP), located in the Ocean Continent Transition (OCT) of the Brazilian South Atlantic rifted margin, is spatially extensive covering an area larger than 63,000 km2 and was emplaced in the Early Cenozoic, approximately 40 Ma after rifted margin formation in Early Cretaceous. The explanation for the origin of the AMP is that it forms part of a hotspot track that initiated at ~85 Ma in the Poxoréu region, an igneous province located ~1500 km to the west of the AMP, within Brazilian continental lithosphere and is presently located under Trindade and Martin Vaz Islands at the Vitoria-Trindade seamount chain (VTC). The aim of this work is to investigate the morphostructure, duration and spatial distribution of the AMP, exploring its significance for the margin evolution and possible origins. The magnetic, reflexion seismic and well data analysis show that the AMP consists of an assembly of large volcanic edifices formed during the Paleogene, each with individual diameters in excess of 50 km, sizes varying from 280 to 2100 km2, and formed by multiple volcanic events. The igneous bodies are mainly buried at different depths (from ~2 Km to 8 km below seafloor), while some emerge to form the Abrolhos Archipelago. The spatial arrangement of the igneous edifices of the AMP suggest that in its central part are the main feeders for the outer and shallower bodies at the borders which have a radial distribution. Their distribution seems to partially follow preexisting structural trends like Precambrian and Mesozoic weakness zones, represented by the onshore Paramirin Aulacogen, the Araçuaí and Ribeira belts, and the offshore rifting structures. These observations suggest an influence of lithosphere inheritance on the emplacement of the AMP. The tectono-stratigraphic architecture indicate margin uplift at Early Cenozoic related to the emplacement of the AMP, creating an elevated area. Mapped hydrothermal vents indicate AMP magmatic activity continued into the Neogene, and connect Abrolhos volcanism with that in the VTC located 650 km to the east. This and reported low S-wave velocity from tomographic model and anomalous dynamic topography suggest a distinct mantle thermal structure under the AMC and VTC. However, the spatial extent and duration of the AMP are inconsistent with a fixed hotspot mechanism and linear trail.

The Unique Amphipoda and Tanaidacea (Crustacea: Peracarida) Associated With the Brown Algae Dictyota sp. From the Oceanic Trindade Island, Southwestern Atlantic, With Biogeographic and Phylogenetic Insights

Oceanic islands are known by their unique evolutionary histories and high endemicity caused by isolation. This is the first survey on the biodiversity of Peracarida from Trindade Island, a volcanic island located about 1,160 km off the Brazilian coast, with the first reports of Tanaidacea from the island and the description ofSynapseudes isissp. nov. and three new species of Amphipoda (Ampithoe thaixsp. nov.,Elasmopus gabrielisp. nov., andEusiroides lucaisp. nov.). The results of the phylogenetic analysis ofSynapseudesbased on morphological characters and its biogeography through the Bayesian Binary MCMC analysis (BBM) suggested an Indo-Pacific origin for the genus. Finally, the biodiversity of Trindade Island is compared to that of the Abrolhos Archipelago, the closest islands from the coast on the continental shelf, suggesting a high endemicity of Peracarida, corresponding to 44% of Amphipoda and 50% of Tanaidacea species in the island of Trindade.

Transatlantic Movement of Domestic PIGEONS Columba livia domestica

Historically, Domestic pigeon (Columba livia domestica Gmelin,1789) (Columbiformes, Columbidae) breeders use the species to promotes race competitions which over the time could select traits to increase the flight performance and spatial orientation capabilities. Although the species has remarkable navigational abilities, it is possible that these birds sometimes become disoriented pushing the individuals to fly off-course and over distances larger than usual. Here we report a Domestic Pigeon ringed in the Canary Islands (Spain) observed in the Abrolhos Archipelago, eastern Brazil, and compiled similar events (N = 5) in the Southwest Atlantic Ocean coast. Our results indicate that these events are largely unnoticed in the scientific literature as most of them were found in non-scientific newspaper and academic conferences, thus, untraceable from scientific databases as Scopus and Google Scholar. As domestic pigeons are possible intermediate hosts of diseases, we encourage the creation of a systematized database of this kind of movements of these birds, including the profile of these vagrants and the circumstances in which these events occur, which can be a basis to be used for scientists and decision makers.

Genomic evidence of recent hybridization between sea turtles at Abrolhos Archipelago and its association to low reproductive output

Hybridization between sea turtle species occurs with particularly high frequency at two adjacent nesting areas in northeastern Brazil. To understand the outcomes of hybridization and their consequences for sea turtle conservation, we need to evaluate the extent of hybridization occurrence and possible deleterious effects in the hybrid progeny. Thus, we investigated the hypothesis of the existence of a new hybrid spot offshore of Brazil’s northeastern coast. The Abrolhos Archipelago is surrounded by the largest and richest coral reefs in the South Atlantic and is known to be a nesting site for loggerhead turtles (Carettacaretta). In this study, we performed a multidisciplinary investigation into levels of hybridization in sea turtles and their reproductive output in the Abrolhos beaches. Genetic data from mitochondrial DNA (mtDNA) and six autosomal markers showed that there are first-generation hybrid females nesting in Abrolhos, resulting from crossings between hawksbill males (Eretmochelysimbricata) and loggerhead females, and backcrossed hatchlings from both parental species. The type and extent of hybridization were characterized using genomic data obtained with the 3RAD method, which confirmed backcrossing between F1 hybrids and loggerhead turtles. The reproductive output data of Abrolhos nests suggests a disadvantage of hybrids when compared to loggerheads. For the first time, we have shown the association between hybridization and low reproductive success, which may represent a threat to sea turtle conservation.

The brutal events on Houtman Abrolhos following the wreck of the Batavia in 1629.

The flagship of the Dutch East India Company (VOC), the Batavia, was wrecked on the morning of the 4th of June 1629 on an isolated reef of the Houtman Abrolhos islands off the coast of Western Australia. The majority of crew and passengers (180-250, including 30 women and children) were able to reach an island which they called Batavia's Graveyard (now known as Beacon Island). After the commander, Francisco Pelsaert, sailed to Batavia for help, Jeronimus Cornelisz took control. Over the next several months his men raped and murdered at least 125 captive shipwrecked passengers and crew. Upon Pelsaert's return Cornelisz and the ringleaders were tried, had their hands severed, and were executed by hanging. Recent archeological excavations have revealed the nature of the attacks and provided scientific validation of some of the alleged incidents. The Batavia mutiny represents a particularly heinous mass murder in the annals of Australia's maritime history.

Seasonal movements and metapopulation structure of the Australian fairy tern in Western Australia

The Australian fairy tern metapopulation in Western Australian is distributed over an extensive stretch of coastline (≤2500km). Using mark–recapture and coordinated community-based resightings of marked birds, this study reveals important insights into the seasonal movement, interchange and key locations used by Australian fairy terns. The Western Australian metapopulation consists of a widely distributed, partially migratory spring/summer-breeding population and a smaller, winter-breeding, sedentary population on the Pilbara coast. The spring/summer-breeding population winters, primarily, around the northern islands of the Houtman Abrolhos, before migrating to breeding areas as far south as Point Malcolm on the eastern south coast and as far north as the Ningaloo coast (Exmouth). Thus, in Western Australia, Australian fairy terns from the same population reproduce in both tropical and temperate marine regions. Associations between birds, persisting over multiple seasons, suggest that group adherence may be an important behavioural trait of these small terns. Based on the recent use of breeding sites and the likely spatial extent of exchange of breeding adults and natal recruits, seven ‘neighbourhoods’ are proposed, which likely represent the best units to underpin a conservation strategy for this threatened coastal seabird. The combination of small population size, strong area fidelity and the potential for strong group adherence among individuals are important considerations for the development of effective conservation strategies in Western Australia. Maintaining the Australian fairy tern population size within the suggested management units is critical for the long-term conservation of this species.

The Zeewijk Story and the Missing Second Wreck

The Dutch East India Company (VOC) ship Zeewijk was wrecked on Half Moon Reef in the Pelsaert (southern) Group of the Houtman Abrolhos islands off the Western Australian coast in 1727. The survivors were able to land on a nearby island, where they eventually built a rescue boat and finally reached their intended destination of Batavia (modern Jakarta) nine months later. At the time of the wreck, the survivors reported evidence of another shipwreck in the area. This paper describes these chronological events, the archaeological investigations and surveys of the site; and it attempts to analyse the veracity of the evidence of a second wreck.

Environmental correlates of reptile variation on the Houtman Abrolhos archipelago, eastern Indian Ocean

AbstractAimTo examine the relationships between island environmental attributes, both biotic and abiotic, and three measures of reptilian variation—species assemblage, species richness and body size distributions.LocationHoutman Abrolhos archipelago, Western Australia.TaxonReptiles.MethodsNineteen islands were sampled from 2002 to 2012 using foraging and trapping. Body size (snout‐vent length) was measured on first capture. Island size varied from 0.3 to 587 ha, encompassing the three geomorphic island types, the three bathymetric groups and a range of other environmental attributes.ResultsFrom about 1,500 captures, 24 reptile species were recorded, including three previously undocumented on the archipelago, and 54 records of species not previously recorded on specific islands. Four significantly different reptile assemblage groups were identified. These were highly correlated with geomorphological composition—two groups encompassing the three large aeolianite islands; another the high rock islands and the largest composite island; and a fourth consisting of the remaining composite islands with one very small high rock island. Both assemblage and richness on islands were significantly correlated with island area, geomorphology and native plant species richness. Of the 13 species captured frequently, 11 showed statistically significant inter‐island variation in body size, and two exhibited sexual dimorphism. In three species, size was also correlated with environmental attributes, including reptile species richness, native plant richness, geomorphology and island area. Six of the eleven species captured on the two largest islands (both aeolianite) differed in size on these adjacent islands.Main ConclusionsHigh inter‐island variation in body size and assemblage composition suggest strong differential selection since the most recent isolation event at 6,500 bp. Anthropogenic disturbances over the last 150 years have resulted in several island extinctions. Species assemblage and richness are strongly associated with environmental attributes. Inter‐island body size variation in three species revealed idiosyncratic responses to environmental pressures. Results provide guidance for effective conservation and management strategies, and evidence for the extinction debts inherent in more recently fragmented mainland habitats.

Partial mortality of intertidal corals due to seasonal daytime low water levels at the Houtman Abrolhos Islands

Extensive partial mortality of intertidal corals was observed at the Houtman Abrolhos Islands, Western Australia, associated with extended and recurrent daytime low water levels from September to November 2018. Branching Acropora corals on shallow leeward reef platforms were emersed during the middle of day during the Austral spring due to diurnal tidal influences, seasonal mean sea-level minima associated with the southward flowing Leeuwin Current and interannual variability related to the El Nino–Southern Oscillation. Pre-emersion total live coral cover was estimated to be ~ 35%, dominated by Acropora (~ 24%). Post-emersion, live Acropora cover decreased to 11.1% (± 1.5 SE) and total cover to 21.7% (± 0.8 SE). Mortality of non-acroporid corals which were lower in the water column was not observed. Partial coral mortality associated with seasonal low tides and interannual variability in mean sea level is a universal process and under-reported driver of temporal variability in coral cover on intertidal reef platforms.

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This work analyzes the time series of wind speeds in different regions of the state of Bahia and the Abrolhos Archipelago, Brazil, through the use of the DFA technique (Detrended Fluctuation Analysis) to verify the existence of long-range correlations and associated power laws. The time series of wind velocities are derived from measurements with hourly means that are acquired in three towers equipped with anemometers at heights of 80, 100, 120 and 150 m, and in the Abrolhos Archipelago with measurements taken at 10 m. These measurements are then compared with numerical simulations of the wind speed obtained with the WRF mesoscale model (Weather Research and Forecasting model). In the onshore case, the results of the application of the DFA technique in the measured and simulated datasets show correlations with power laws in two regions of distinct scales (subdiffusive and persistent) for both time series. It is suggested that this occurs due to the mesoscale effects and local circulations acting on the planetary boundary layer, where the turbulence in the daily cycle is generated by thermal (buoyancy) and mechanical (wind shear) forcing. However, in regions that are not subject to local-effect conditions, such as small islands far from the mainland, the synoptic effects are the most important and active in the maritime boundary layer, so the series of real and simulated datasets exhibit only subdiffusive behavior.

Preliminary observations of corallivorous Drupella cornus feeding aggregations at Rottnest Island, Western Australia

Predation by the corallivorous gastropod Drupella cornus is well studied in the tropical and subtropical waters of the Indo-Pacific, including Ningaloo Reef and the Houtman Abrolhos Islands, Western Australia. In 1983, Drupella was not found in the Pocillopora colonies of Rottnest Island (Black and Prince 1983), and there has only been one record of D. cornus on Rottnest Island until today. We show the first feeding aggregations of D. cornus on these higher-latitude reefs of Rottnest Island, and highlight the importance of these findings.

Analysis of long-range correlations of wind speed in different regions of Bahia and the Abrolhos Archipelago, Brazil

This work analyzes the time series of wind speeds in different regions of the state of Bahia and the Abrolhos Archipelago, Brazil, through the use of the DFA technique (Detrended Fluctuation Analysis) to verify the existence of long-range correlations and associated power laws. The time series of wind velocities are derived from measurements with hourly means that are acquired in three towers equipped with anemometers at heights of 80, 100, 120 and 150 m, and in the Abrolhos Archipelago with measurements taken at 10 m. These measurements are then compared with numerical simulations of the wind speed obtained with the WRF mesoscale model (Weather Research and Forecasting model). In the onshore case, the results of the application of the DFA technique in the measured and simulated datasets show correlations with power laws in two regions of distinct scales (subdiffusive and persistent) for both time series. It is suggested that this occurs due to the mesoscale effects and local circulations acting on the planetary boundary layer, where the turbulence in the daily cycle is generated by thermal (buoyancy) and mechanical (wind shear) forcing. However, in regions that are not subject to local-effect conditions, such as small islands far from the mainland, the synoptic effects are the most important and active in the maritime boundary layer, so the series of real and simulated datasets exhibit only subdiffusive behavior.

Environmental changes reflected by sedimentary geochemistry for the last one hundred years of a tropical estuary

Abstract Based on multiple proxies, such as major and trace elements, mineralogy, Corg/Ntotal ratio and δ13C, we assessed the natural and anthropogenic depositional record in a tropical estuary (Caravelas, Brazil). The Caravelas estuary was once a pristine area of highly important ecological role, due to its mangroves and proximity to the largest reef system in the South Atlantic (Abrolhos Archipelago). However, during the past decades, the estuary has been subjected to both natural and anthropogenic impacts, such as a natural opening of an inlet and changes in land use. This study is based on three dated cores, taken from the inlet to the main channel. A shift in the organic and inorganic proxies, in the early 1960s, shows the impact of this natural opening on the hydrodynamics and sediment distribution. Furthermore, there is a clear spatial pattern in the contribution of the main sources to the organic matter content in the cores: the core collected further away from the inlet shows a strong C3 plant contribution while the ones recovered closer show a higher marine influence. Only a slight increase in enrichment factors of the selected trace metals has been observed and they have been attributed to land use changes rather than direct inputs from industrial and urban sources. Such information is vital for the effective management of coastal systems, mainly when considering natural and ongoing anthropogenic changes in its forcing conditions that are exacerbated by climate change.

Summer micro- and mesozooplankton from the largest reef system of the South Atlantic Ocean (Abrolhos, Brazil): Responses to coast proximity

Zooplankton samples were collected in summer and in three distinct Neotropical areas (the coastal reef arc, the outer reef arc and the Abrolhos Archipelago). Two stations in each sampling area were established (a reef station and an outer station) to sampling zooplanktonic assemblage with two different mesh sizes (64- and 200-μm plankton nets). Approximately 110 taxa were identified, and the assemblages from the two nets were significantly different. Zooplankton abundances were three orders of magnitude higher in the 64-μm net samples with an average abundance of 217,000 ± 93,418 ind m−3 (64-μm net) and 189 ± 122 ind m−3 (200-μm net). A permutational multivariate analysis of variance (PERMANOVA) of the zooplankton community structure revealed significant differences between all three regions and showed a heterogeneous distribution of these animals, even though no significant differences were observed in terms of abundance for both net catches (two-way ANOVA, P > 0,05). SIMPER analyses showed that most highly abundant taxa occurred in all sampling areas. Though, some other taxa were clearly identified as characteristic of a particular area by their relative frequency, rather than relative abundance. It is hypothesized that variations in suspended particle concentration play an important role in the observed differences in community composition. Our results suggest that the pelagic components of these reef zooplankton assemblages may be as important as demersal zooplankters to benthic-pelagic coupling. Because the much higher abundance of the microzooplankton assemblages compared to the mesozooplankton is a common feature of reef communities, the studies that use only coarse nets miss assessing the contribution of a large and important portion of the reef zooplankton assemblage and therefore misinterpret the community as a whole.

Distribution and patterns of migration of a tropical seabird community in the Eastern Indian Ocean

We present the first detailed data on the distribution and migration patterns of four pelagic seabird species in the Eastern Indian Ocean—the Lesser Noddy (Anous tenuirostris melanops), Brown Noddy (Anous stolidus), Wedge-tailed Shearwater (Ardenna pacifica) and Bridled Tern (Onychoprion anaethetus) breeding at the Houtman Abrolhos and the Wedge-tailed Shearwater breeding at Varanus Island, Western Australia—tracked using geolocators during their respective non-breeding periods. Lesser Noddies remained largely in the general vicinity or slightly to the south of the colony in their non-breeding season (February–September). Brown Noddies spent their non-breeding period (March–August) in the Northwest Shelf area of Western Australia, around 950 km north of the colony. In contrast, Bridled Terns and most Wedge-tailed Shearwaters undertook extensive non-breeding migrations. Wedge-tailed Shearwaters occupied waters adjacent or to the north of their nesting sites or migrated 4200 km northwest into the equatorial central Indian Ocean near the Ninety East Ridge during the non-breeding season (late April to mid-November). These same areas were used during the sabbatical summer by Wedge-tailed Shearwaters that had deferred breeding. Bridled Terns spent their non-breeding period (April–September) in the Celebes Sea, 3800 km north of the Houtman Abrolhos. The results are discussed in the context of potential marine threats to the different species during the non-breeding period.

New records of association between caridean shrimps (Decapoda) and sponges (Porifera) in Abrolhos Archipelago, northeastern Brazil

New records of association between caridean shrimps (Decapoda) and sponges (Porifera) in Abrolhos Archipelago, northeastern Brazil

Does fish behaviour bias abundance and length information collected by baited underwater video?

Baited remote underwater stereo-video systems (stereo-BRUVs) are commonly used to sample fish assemblages across areas of differing fish densities with little consideration of how intraspecific and interspecific behaviours may influence estimates of abundance and body-size distribution. To investigate these potential biases, the current study compared the abundances and body-size distributions of seven target carnivorous species and six lower trophic level non-target species, across sites with high and low densities of large-bodied target species, using Stereo-BRUVs. Samples were collected inside and outside of an area closed to fishing at the Houtman Abrolhos Islands, Western Australia. Densities of large-bodied target species were found to be higher inside the closed fishery area, compared to similar areas outside. The presence of large-bodied target species did not appear to influence the body-size distribution of conspecifics, or the abundance and body-size distribution of small-bodied non-target species throughout the deployments. The abundance of large-bodied target species was found to peak earlier in deployments within the closed area than the areas open to fishing. This difference may be due to the higher relative density with the closed area, which may result in shorter arrival times as fish move towards the baited video, and/or to behavioural differences, as fish within the closed area may approach the baited video more readily. This potential behavioural difference between areas closed and open to fishing has important implications for duration of baited video sampling times, and we suggest that shorter deployments times (<15min) are less likely to bias abundance estimates of fishery target species.

Taxonomy and phylogeny of calcareous sponges (Porifera: Calcarea: Calcinea) from Brazilian mid-shelf and oceanic islands

Despite the enormous economic, scientific and strategic value of the Brazilian oceanic and mid-shelf islands (BOMIs), the biological communities of these islands are still poorly known. An example is their fauna of calcareous sponges (Porifera: Calcarea), with only six species described up to date. In the present study, we analysed the Calcinean sponges from the mid-shelf Abrolhos Archipelago and four of the five Brazilian oceanic islands (São Pedro e São Paulo Archipelago, Fernando de Noronha Archipelago, Rocas Atoll, and Trindade Island), using both morphological and molecular approaches for taxonomy. Fourteen species were found, of which 12 are new to science: Arturia trindadensis sp. nov., Borojevia tenuispinata sp. nov., B. trispinata sp. nov., Clathrina insularis sp. nov., C. lutea sp. nov., C. mutabilis sp. nov., C. zelinhae sp. nov., Ernstia citrea sp. nov., E. multispiculata sp. nov., E. rocasensis sp. nov., E. sanctipauli sp. nov., and E. solaris sp. nov. These results raised in 63% the species richness of calcareous sponges from the BOMIs. Clathrina aurea and Leucetta floridana were recollected and the former had its geographical distribution expanded. The molecular tree obtained confirmed the morphological identifications and allowed a discussion about the evolution of morphological characters, and the usefulness of some of those characters in the taxonomy of Calcinea.

Genetically diverse herpesviruses in South American Atlantic coast seabirds.

Different herpesviruses have been associated with respiratory and enteric disease and mortality among seabirds and waterfowl. In 2011, a respiratory disease outbreak affected 58.3% (98/168) of the Magellanic penguins undergoing rehabilitation due to an oil spill off the southern Brazilian coast. Etiology was attributed to a novel herpesvirus identified by histopathology, immunohistochemistry, electron microscopy and molecular studies with partial DNA sequencing. Since migration, rehabilitation and translocation may facilitate the spread of pathogens between populations and trigger the onset of clinical disease in animals with latent infections, investigation of herpesvirus occurrence in asymptomatic seabirds was performed. Samples from free-ranging seabirds were collected in Argentinian Patagonia (Magellanic penguins) and the Abrolhos Archipelago in Brazil (Brown boobies, Masked boobies, Red-billed tropicbirds, White-tailed tropicbirds and South American tern). Furthermore, asymptomatic seabirds housed at the facility where the outbreak occurred were also sampled. In total, 354 samples from eight seabird species were analyzed by PCR for herpesvirus. Four different sequences of herpesviruses were identified, one in Yellow-nosed Albatross, one in Boobies and Tropicbirds and two in Magellanic penguins. Magellanic penguin herpesvirus 1 was identified during the penguin outbreak at the rehabilitation facility in Brazil, while Magellanic penguin herpesvirus 2 was recovered from free-ranging penguins at four reproduction sites in Argentina. Phylogenic analysis of the herpesviruses sequences tentatively identified suggested that the one found in Suliformes and the one associated with the outbreak are related to sequences of viruses that have previously caused seabird die-offs. These findings reinforce the necessity for seabird disease surveillance programs overall, and particularly highlight the importance of quarantine, good hygiene, stress management and pre-release health exams in seabirds undergoing rehabilitation.