Faafu Atoll Research Articles

Application of marine sponges for biomonitoring active pharmaceutical ingredients (APIs) in coral reefs. Optimization of an SPME and ESI-LC-MS/MS method

Chemical pollution is a threat to coral reefs. To preserve them, it is crucial to monitor novel contaminants and assess the related risks. The occurrence of active pharmaceutical ingredients (APIs) in coral reefs has been poorly investigated until now. Under this light, we tested the use of the marine sponge Cf. Hyrtios as bio-monitors and conducted a pilot study in the Faafu Atoll (Maldives). Analyses were carried out by in vivo solid-phase microextraction (SPME) and liquid chromatography (LC) electrospray ionization (ESI) tandem mass spectrometry (MS/MS). Twelve APIs were selected for method optimization. Limits of quantitation (LOQs) were in the 0.6 and 2.5 ng/g range, accuracy between 86.5 % and 104.7 %, and precision between 3.0 % and 14.9 %. All the sponges located in the inner reefs resulted contaminated with at least one API. Gabapentin and Carbamazepine displayed the highest detection rates, while Ketoprofen had the highest concentration (up to 15.7 ng/g).

Bioconcentration and cellular effects of emerging contaminants in sponges from Maldivian coral reefs: A managing tool for sustainable tourism

Tourism is the main income source for the Maldives, but concurrently, it represents a growing threat to its marine ecosystem. Here, we monitored the bioaccumulation of 15 emerging contaminants (ECs) in the Maldivian reef sponges Spheciospongia vagabunda collected in two resort islands (Athuruga and Thudufushi, Ari Atoll) and an inhabited island (Magoodhoo, Faafu Atoll), and we analysed their impact on different sponge cellular stress biomarkers. Caffeine and the insect repellent DEET were detected in sponges of all the islands, whereas the antibiotic erythromycin and the UV filter 4-methylbenzylidene camphor were found in resort islands only. Although concentrations were approximately a few ng/g d.w., we quantified various induced cellular effects, in particular an increase of the levels of the enzyme glutathione S-transferase involved in cell detoxification. Our results highlight the importance to increase awareness on ECs pollution, promoting the use of more environmental friendly products to achieving the sustainable development goals.

A conspicuously coloured new species of the Alpheus macrocheles group from the central Indian Ocean (Decapoda: Alpheidae).

A new snapping shrimp species of the Alpheus macrocheles (Hailstone, 1835) group is described based on a single adult male specimen collected on an exposed forereef near Magoodhoo Island, Faafu Atoll, Maldives. Alpheus dingabadi sp. nov. is one of several species of the A. macrocheles group characterised by the presence of a stout distoventral tooth on the merus of the third pereiopod, but can be separated from all of them by several morphological features, including the unusually long appendix masculina on the second pleopod, as well as by its conspicuous and highly diagnostic colour pattern.

Photographic Checklist, DNA Barcoding, and New Species of Sea Slugs and Snails from the Faafu Atoll, Maldives (Gastropoda: Heterobranchia and Vetigastropoda)

Baseline biodiversity data are key for ecological and evolutionary studies and are especially relevant for areas such as the Maldivian Archipelago in the Indian Ocean, which can act as a stepping-stone for the transport of widely distributed marine species. We surveyed the islands and reefs of the Faafu and Malé Atolls with snorkeling and scuba diving, collecting the two gastropod subclasses, Heterobranchia and Vetigastropoda. Our inventory comprises 104 species photographed alive to create an identification guide. We also provide COI barcodes for most species, adding novel sequence data for the Maldivian malacofauna. Half of our species represent new records for the Maldives, emphasizing how much diversity remains to be discovered. Species distributions reflect ecological rarity, with almost 60% of taxa only found in one site. We also compiled a comprehensive checklist of heterobranchs and vetigastropods of the Maldives based on literature records, resulting in 320 species, which, together with barcoding data, indicate several potential cryptic species in the Indo-Pacific. Six new species are described, the nudibranchs Limenandra evanescenti n. sp., Eubranchus putnami n. sp., Sakuraeolis marhe n. sp., Moridilla maldivensis n. sp., Tergiposacca perspicua n. sp., and the sacoglossan Costasiella fridae n. sp.

Coccolithophore assemblages and a new species of Alisphaera from the Faafu Atoll, Maldives, Indian Ocean

Coccolithophore assemblages were investigated from the Faafu Atoll in November 2018. The surface waters were sampled around the islands of Magoodhoo and Adanga, from the coast to the open water towards both the lagoon and the ocean, as well as waters up to 40 m depth at selected stations. Coccolithophores were scarce close to the coast (0.1–4 × 103 coccospheres/l), increased in abundance towards both the lagoon and the open ocean (20–44 × 103 coccospheres/l) and showed no clear depth trend. The assemblages were dominated by Gephyrocapsa oceanica with a large contribution by species that are typically reported from the mid- to lower-photic zone, i.e., primarily Oolithotus antillarum, followed by Calciosolenia spp., Michaelsarsia adriaticus, Calciopappus rigidus, Ophiaster spp. and Algirosphaera robusta. As for other tropical settings, Emiliania huxleyi made a minor contribution. Taxa that are common in the upper layers of oligotrophic stratified settings like Umbellosphaera spp., Discosphaera tubifera and Rhabdosphaera clavigera were scarce. Overall, such assemblages displayed the characteristics of neritic settings, with high trophic resources and elevated water turbidity, even though the measured chlorophyll-a concentration was low throughout the investigated area.

Reef complexity influences distribution and habitat choice of the corallivorous seastar Culcita schmideliana in the Maldives

AbstractThe cushion seastar Culcita schmideliana has gained major attention in the last few years because of its selective predation on juvenile corals, as well as its ability to generate large demographic assemblages, causing delays in coral recovery after large mortality events in the Republic of Maldives. However, a lack of data regarding the factors affecting its distribution and habitat selection still persists in this area. Here, we adopted a novel approach in the study of corallivorous seastar habitat selection that combined ecological and digital photogrammetry data. In this regard, we tested 3 different parameters as factors influencing seastar habitat choice in the South-East region of Faafu Atoll, Republic of Maldives, namely prey abundance, Linear Rugosity Index (LRI), and Average Slope (AS). The analysis of selectivity coefficient (Ei) of seastars for different habitat types showed a preference for reefs characterized by medium AS values (Ei = 0.268), a LRI included between 2 and 2.5 (Ei = 0.180), and a juvenile coral density ranging between 10 and 20 colonies m−2 (Ei = 0.154). A multiple linear regression analysis showed that different AS and LRI values explained the 43.1% (R2 = 0.431, P = 0.007) and the 48.1% (R2 = 0.481, P = 0.024) of variance in seastars abundance, respectively, while juvenile coral densities did not significantly affect this (R2 = 0.132, P = 0.202). These results provide new information on the distribution and behaviour of an important corallivore of Maldivian reefs, such as C. schmideliana.

Observation of a coral-dwelling gall crab (Cryptochiridae) in a dead coral host highlights their vulnerability to reef degradation

Coral-associated fauna contributes greatly to coral reef biodiversity. Many species are obligately associated with their hosts on which they depend for food and/or refuge from predators. Their close relationship with their hosts makes them vulnerable to coral mortality. Here I report a coral-dwelling gall crab (Cryptochiridae) inhabiting a partially dead Echinopora Lamarck, 1816 coral, at Magoodhoo Island, Faafu Atoll, Maldives. Cryptochirids are thought to feed off the mucus provided by their coral host, although some questions about their feeding biology remain. This observation highlights that these crabs remain associated with a dead host, even if it can no longer provide nutrients. The strong host association makes gall crabs vulnerable to widespread habitat degradation.

Marine Fouling Characteristics of Biocomposites in a Coral Reef Ecosystem

AbstractCoral reefs are among the most diverse ecosystems in the world. The diversity of life found in the habitats created by corals is so large that the reefs are known as the “rainforests of the sea.” Unfortunately, severe natural and anthropogenic changes such as ocean warming, acidification, coral diseases, and plastic pollution are extremely detrimental to this ecosystem. To enrich the ambient conditions of the corals and boost their growth, the potential of two biocomposites is evaluated based on biodegradable polyurethane and silicone matrices as scaffolds for the growth of oceanic organisms. Furthermore, their degradation is investigated within the coral reefs of Faafu Atoll, Republic of Maldives. The observations indicate that there are a significant number of organisms that settle and grow on these biocomposites in the Maldivian lagoon, both of an animal and photosynthetic nature. The biocomposites have the potential to become suitable scaffolds for diverse hard bottom fouling organisms. Moreover, the presence of coral larvae on the biocomposites suggests that during their biodegradation, these biocomposites can support the growth of organisms, generating a suitable environment for triggering the birth of new corals.

Freshwater system of coral inhabited island: Availability and vulnerability (Magoodhoo Island of Faafu Atoll – Maldives)

Freshwaters constitute a fundamental and extremely limited resource for atoll islands' population. The interplay of climatic and human-driven processes, which affect both the quantity and the quality of freshwater resources, may exacerbate the problem of water security and availability. This work evaluated the effects of good spectrum of anthropic impacts on groundwater quality in a typical and representative native inhabited island (c.a. 850 people) of Maldives, analyzing and interpreting hydrological and hydrochemical data, collected during a specific field survey on 51 sampling points after a rainy season. The island groundwater is constituted by a thin asymmetric lens, periodically recharged by rain. The lifestyle of people and water exploitation seem to be sustainable, even if groundwater resources are already experiencing moderate contamination and, limited to some areas, heavy pollution. The sources of impacts have been identified in diffuse organic matter contamination due to a poor domestic wastewater treatment, farming (poultry) and gardening activities. To face these impacts, it is essential to build a sewer system paired with a possibility to recycle wastewater reducing water over-exploitation. The collaborative and educational initiatives organization, at different levels, can increase the capacity for planning a sustainable development.Our results provide useful information for sustainable management plans to preserve freshwater resources of the island, which conservation is especially important considering the context of the future lifestyle changes and climatic scenarios for the Maldives. These findings can be extended by analogy to others atoll islands.

Water Resource Management and Sustainability: A Case Study in Faafu Atoll in the Republic of Maldives

This paper contributes to the existing literature in proposing an integrated approach to water management and energy renewable production in a fragile environment. After the 2004 tsunami, in many outer islands in The Republic of Maldives, the lens freshwater natural reservoir was deeply damaged. Currently, the populations of rural atolls use rainwater and water in plastic bottles imported from the mainland for drinking. To provide safe and sustainable drinking water, we analyze the feasibility of two different actions: a desalination system fed by a diesel plant or by a photovoltaic (PV) plant with batteries. The current situation (business as usual, (BAU)) is also evaluated and taken as a benchmark. After illustrating the technical and economic features of desalination and PV plants, a financial and environmental analysis is conducted on the two alternatives plus BAU, showing that the desalination fed by the PV plant results in optimization both on the financial and the environmental side. The levelized cost of water (LCOW) and the CO2 levelized emissions of water (LEOW) are calculated for each alternative. The case study is developed in Magoodhoo Island, Faafu Atoll and can be extended to other islands in The Republic of Maldives and in general to small island developing states (SIDS).

A Mesophotic Hotel: The Octocoral Bebryce cf grandicalyx as a Host

Mesophotic coral reefs are ecosystems found below 30 m and down to 150 m depth. Even though interest in these ecosystems has increased in recent years, several aspects still need further attention, including symbiotic associations. During survey of the upper mesophotic reefs in Faafu Atoll, Republic of Maldives, we observed a stable, and likely mutualistic, association between the octocoral Bebryce cf grandicalyx, a sponge belonging to the family Suberitidae, and the hydrozoan Zanclea timida. Additionally, several other organisms were found dwelling on the octocoral and sponge surface, including amphipods, barnacles, entoprocts, flatworms, brittle stars, and foraminiferans. These photographs illustrate the article “A mesophotic hotel: the octocoral Bebryce cf grandicalyx as a host” by D. Maggioni, S. Montano, O. Voigt, D. Seveso and P. Galli published in Ecology. https://doi.org/10.1002/ecy.2950

Geophysical approach to study the potential ocean wave-induced liquefaction: an example at Magoodhoo Island (Faafu Atoll, Maldives, Indian Ocean)

This paper presents an application of geophysical techniques to determine the liquefaction potential of the surface sand layer under wave loading in an atoll island, Magoodhoo Island (Faafu Atoll). Measurements of background noise (H/V technique), seismic refraction profiles (tomography), surface wave inversion and electrical resistivity tomography were applied to study the properties of the substratum. Geotechnical analysis provided the relative soil density (Dr = 55%) and the grading curves; the comparison of these parameters with geophysical data, allowed to identify indicative features related to ground liquefaction phenomena. Microtremor measurements calculated a fundamental site resonance in the frequency range of 1.42–23.19 Hz. Velocity profiles showed that bedrock interface depth varies from approximately z = 35 m north-east of the island, to z = 25 m south-west, while in the most north-eastern external area, it was not detected. These results suggested a significant lateral variability of the site seismic response throughout the study area. Liquefaction triggering with wave heights varying between 2.0 and 3.0 m and 70–300 cycles was calculated. Also, considering an average wave period of 6 s, liquefaction was more likely after 7–30 min. The soil vulnerability index Kg was also used to evaluate the soil liquefaction hazard suggesting that the north-eastern island sector is more susceptible to liquefaction, confirmed also by the building damage status as compared to other areas of the island. The results obtained in the survey highlight that in an atoll island, where potential disasters can be caused by several natural causes, saturated loose sands lose their strength and stiffness if subjected to wave loading.

Microplastics as a threat to coral reef environments: Detection of phthalate esters in neuston and scleractinian corals from the Faafu Atoll, Maldives

The impact of microplastics (MPs) on reef-building corals are still largely unknown. The scientific literature provides evidence from lab feeding trials that coral may ingest MPs. Several adverse effects, i.e., necrosis and bleaching, have also been highlighted. However, field studies are limited. Here, we investigated for the first time the possible correlation between MP seawater contamination and the presence of phthalic acid esters (PAEs), a class of MP-associated contaminants, in scleractinian corals. The survey was carried out in a remote coral reef atoll in the Indian Ocean located in the Maldivian archipelago, considered as a case study. MPs and PAEs were monitored in subsurface neustonic tow samples and scleractinian corals across twelve sampling sites. The results showed widespread MP contamination and the presence of appreciable levels of PAEs in the scleractinian corals sampled inside the atoll rim near an inhabited island, which correlated with the highest MP concentration.

New insights into the ecology and corallivory of Culcita sp. (Echinodermata: Asteroidea) in the Republic of Maldives

Although corallivory is recognized as a threat affecting the structure and integrity of coral reef habitats, ecological data on most species of coral consumers remain limited, slowing down the development of conservation and restoration strategies of the reef ecosystems. In this study, the population distribution and corallivorous behaviour of the cushion sea star Culcita sp. were investigated in the south region of Faafu Atoll, Maldives. Most sea stars were found on reef slopes within 0–10 m depth and in areas characterized by low live coral cover. Several coral genera were preyed on by the sea star. Although most of the consumed corals belong to the genus Acropora, a feeding preference for the genera Pocillopora and Pavona and a consistent avoidance of the genus Porites were observed. Furthermore, the majority of the prey corals were small colonies (< 10 cm diameter), even though Culcita sp. appeared to be capable of partially consuming larger colonies. Dietary preferences for specific coral colonies or genera have the potential to generate local shifts in coral community composition and structure and may affect reef recovery following natural and anthropogenic disturbance in an already impacted environment such as the Maldivian reefs.

Microplastic and charred microplastic in the Faafu Atoll, Maldives

Microplastics are recognized as a growing threat for the marine environment that may even affect areas generally considered pristine. In this work we surveyed the microplastic contamination in the Faafu Atoll (Maldives, Indian Ocean) across twelve sampling station, located either inside or outside the reef rim. Sediments and seawater samples were collected. Despite the remoteness of the atoll, the scarce local population and low touristic annual afflux, the detected average abundance were 0.32 ± 0.15 particles/m3 in the surface water and 22.8 ± 10.5 particles/m2 in the beach sediments. Polymers identified through Fourier-Transform Infrared spectroscopy were mostly polyethylene, polypropylene, polystyrene, polyvinylchloride, polyethyleneterephtalate, and polyamide. Elastomeric residues and charred microparticles were also found. In particular, the charred microparticles were prevalently located nearby the inhabited island and they might be considered a peculiarity of the area, related to local practice of burning plastic waste at the shoreline.

Spatial variability in distribution and prevalence of skeletal eroding band and brown band disease in Faafu Atoll, Maldives

Indo-Pacific coral diseases are currently considered one of the 15 globally important threats requiring conservation attention. The coral reefs of the Maldives are experiencing a local decline, with the presence of some coral diseases reported only recently. We investigated the spatial variability in prevalence and distribution of two protozoan diseases, skeletal eroding band (SEB) and brown band disease (BrB), in three islands in the Faafu Atoll: an inhabited island (Magoodhoo), an uninhabited island (Adanga) and a resort island (Filitheyo). Our study revealed a low level of mean disease prevalence for both diseases (<1 %), with Magoodhoo and Adanga being the most affected by BrB and SEB, respectively. However, our preliminary temporal investigations revealed an increment of both coral diseases in Adanga during the last 4 years. Furthermore, we observed different spatial patterns between the two diseases, with SEB positively correlated to dead coral coverage. Finally, Acropora was the most affected coral genus, hosting both coral diseases. Considering that Acropora is the most abundant genus in the archipelago and many other areas in the Indo-Pacific, this finding highlights the need for particular conservation efforts for this genus. These results represent just a first step in the assessment of Maldivian coral disease epidemiology, and more detailed analyses of regional differences in diseases prevalence are needed to further explore their impacts on Maldivian coral reefs.

Ingolfiellamaldivensis sp. n. (Crustacea, Amphipoda, Ingolfiellidae) from coral reef sand off Magoodhoo island, Maldives.

A new species of marine interstitial wormshrimp, Ingolfiella maldivensis, is described from coral sand on the inner and outer reef off Magoodhoo island, Faafu atoll, Maldives. Six females were found and compared to other species from the Maldives and those bordering the Indian Ocean and beyond. Morphological resemblance ties it to a species from the Caribbean island of Curaçao. Both species are found in shallow sublittoral interstitial spaces.

Slow progression of black band disease in Goniopora cf. columna colonies may promote its persistence in a coral community

Coral diseases have been little investigated in the Indian Ocean and especially in the Republic of Maldives, where they were firstly observed in 2010. Through repeated monitoring, we observed a peculiar slow progression of Black Band Disease in several large colonies of the reef-building coral Goniopora cf. columna in the Maldivian reefs of Magoodhoo Island (Faafu Atoll). We argue that this may ensure the local persistence of the disease, possibly promoting long-term mortality of other, more susceptible coral species.

A checklist of phytoplankton species in the Faafu atoll (Republic of Maldives)

1 - Phytoplankton is considered as a natural bioindicator of water quality because of its sensitivity and its complex and rapid response to change of environmental conditions. 2 - The aim of this study was to investigate and provide important new information about the checklist of phytoplankton species in different lagoons of the Faafu atoll in Maldivian archipelago. 3 - A total of 140 phytoplankton taxa were identified. In terms of species richness, dinoflagellates were the largest group with 55 identified taxa belonging to 22 genera. Coscinodiscophyceae recorded 38 taxa belonging to 14 genera; Bacillariophyceae represented by 18 taxa belonging to 10 genera and Fragilariophyceae recorded 11 taxa belonging to 8 genera. Most of the other classes were poorly represented with only one or , at most, two taxa for each genus.

First report of coral diseases in the Republic of Maldives

Little is known about coral diseases in the Indian Ocean region, especially in the Republic of Maldives. This study aimed at documenting the presence of coral diseases in the archipelago of the Maldives. Surveys for lesions in scleractinians conducted at 8 sites around Magoodhoo Island (Faafu Atoll) in October and November 2010 led to the identification of 5 coral diseases and 1 anomalous pigmentation response affecting 8 hard coral genera. White syndrome, skeleton-eroding band disease, black band disease, and Porites dark discoloration response were the most commonly observed conditions. In contrast with several reports of other reef systems, the overall observed prevalence of coral diseases was rather low (<2%), with individual prevalence ranging from 0.7% for skeleton-eroding band to 0.18% for Porites dark discoloration response. These data represent the first report of coral diseases for the Republic of Maldives.