Toliara, Madagascar

University of Toliary
Toliara, Madagascar
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Terrana L.,University of Mons | Eeckhaut I.,University of Mons | Eeckhaut I.,University of Toliary
Zootaxa | Year: 2017

Eenymeenymyzostoma nigrocorallium n. sp. is the first species of myzostomid worm associated with black corals to be described. Endoparasitic specimens of E. nigrocorallium were found associated with three species of antipatharians on the Great Reef of Toliara. Individuals inhabit the gastrovascular ducts of their hosts and evidence of infestation is, most of the time, not visible externally. Phylogenetic analyses based on 18S rDNA, 16S rDNA and COI data indicate a close relation to Eenymeenymyzostoma cirripedium, the only other species of the genus. The morphology of E. nigrocorallium is very unusual compared to that of the more conventional E. cirripedium. The new species has five pairs of extremely reduced parapodia located on the body margin and no introvert, cirri or lateral organs. Individuals are hermaphroditic, with the male and female gonads both being located dorsally in the trunk. It also has a highly developed parenchymo-muscular layer on the ventral side, and the digestive system lies in the middle part of the trunk. A three-dimensional digital model of this worm's body plan has been constructed whereby the external morphology and in toto views of the observed organ systems (nervous, digestive and reproductive) can be viewed on-screen: © Copyright 2017 Magnolia Press.

Archibald D.B.,St. Francis Xavier University | Archibald D.B.,University of Adelaide | Collins A.S.,University of Adelaide | Foden J.D.,University of Adelaide | Razakamanana T.,University of Toliary
Journal of Geology | Year: 2017

The East African Orogen is one of the largest orogens that formed during the Ediacaran to Cambrian amalgamation of Gondwana. In the Mozambique Belt, the East African Orogen represents the amalgamation of Neoproterozoic India with the Congo-Tanzania-Bangweulu Block. In the Arabian-Nubian Shield, the orogen consists of a pre-Neoproterozoic continental terrane surrounded by Neoproterozoic juvenile oceanic arc–like terranes. A large ocean named the Mozambique Ocean divided these Neoproterozoic landmasses. Many oceanic sutures tie together the various terranes in the northern orogen, but the location of potential sutures become less obvious moving south. The ca. 100 My duration of subduction of the Mozambique Ocean resulted in voluminous magmatism in Madagascar, named the Imorona-Itsindro Suite, but the location of possible suture zones in Madagascar is controversial. Understanding the petrogenesis of this suite is critical for developing Neoproterozoic paleogeographic plate reconstructions. The Tonian age of the Imorona- Itsindro Suite is well documented, but the geochemistry of the suite provides ambiguous evidence for the tectonic setting. Geochemically, these rocks are predominantly calc-alkaline, with characteristics consistent with emplacement within a volcanic or continental arc. The suite has variable but mostly high87Sr/86Sr and low143Nd/144Nd signatures, indicating significant crustal involvement. Changes in subduction-zone dynamics, accompanied by variable crustal anatexis and assimilation, contributed to geochemical ambiguities that have prompted some authors to suggest an active rift as an alternative tectonic model. However, the geochemical signatures are more compatible with an Andean-like arc tectonic setting. We suggest that a prolonged history of subduction (1100 My) provided sufficient time for the continental arc to mature and for the development of shallow mantle source metasomatism. © 2017 by The University of Chicago.

McClanahan T.R.,Wildlife Conservation Society | Abunge C.,Wildlife Conservation Society | Rabearisoa A.,Wildlife Conservation Society | Mahatante P.,University of Toliary | And 2 more authors.
Ecology and Society | Year: 2014

Perceptions of the benefits of fisheries management restrictions were evaluated in coastal Madagascar to identify restrictions that are likely to be self- and community enforced. The survey focused on 24 Malagasy fishing villages adjacent to coral reefs. Resource users' perceptions of the benefits of restrictions were generally high and widespread, but some less positive perceptions were found in three villages located near marine protected areas. Perceptions of the benefits of gear restrictions had widespread support; closed areas, seasons, and minimum sizes of fish were less common; and restrictions on species were supported infrequently. We therefore advocate a management implementation approach that uses these scales of perceived benefits and prioritizes support for the most widely accepted restrictions most broadly, with the less accepted restrictions matched to specific supportive locations. At the village level, socioeconomic and wealth variables were not clearly associated with perceived benefits, which we suggest results from a stronger influence of village history than socioeconomic conditions. At the individual fisher level, however, there was evidence that experienced people involved in decision-making, having livelihood alternatives, and having permanent housing had more opinions and frequently were more supportive of management restrictions. Incorporating this information into forums and management plans is expected to increase the rate of adoption and compliance with needed fisheries restrictions. © 2014 by the author(s).

Collins A.S.,University of Adelaide | Collins A.S.,University of Sao Paulo | Kinny P.D.,Curtin University Australia | Razakamanana T.,University of Toliary
Gondwana Research | Year: 2012

Southern Madagascar is the core of a >1million km 2 Gondwanan metasedimentary belt that forms much of the southern East African Orogen of eastern Africa, Madagascar, southern India and Sri Lanka. Here the Vohibory Series yielded U-Pb isotopic data from detrital zircon cores that indicate that it was deposited in the latest Tonian to late Cryogenian (between ~900 and 640Ma). The deposition of the Graphite and Androyen Series protoliths is poorly constrained to between the late Palaeoproterozoic and the Cambrian (~1830-530Ma). The Vohibory Series protoliths were sourced from very restricted-aged sources with a maximum age range between 910 and 760Ma. The Androyen and Graphite Series protoliths were sourced from Palaeoproterozoic rocks ranging in age between 2300 and 1800Ma. The best evidence of the timing of metamorphism in the Vohibory Series is a weighted mean 206Pb/ 238U age of 642±8Ma from 3 analyses of zircon from sample M03-01. A considerably younger 206Pb/ 238U metamorphic age of 531±7Ma is produced from 10 analyses of zircon from sample M03-28 in the Androyen Series. This ~110Ma difference in age is correlated with the early East African Orogeny affecting the west of Madagascar along with its type area in East Africa, whereas the Cambrian Malagasy Orogeny affected the east of Madagascar and southern India during the final suturing of the Mozambique Ocean. © 2010 International Association for Gondwana Research.

Cerchio S.,New England Aquarium | Cerchio S.,Woods Hole Oceanographic Institution | Andrianarivelo N.,University of Toliary | Andrianantenaina B.,University of Toliary
Advances in Marine Biology | Year: 2015

The Indian Ocean humpback dolphin (Sousa plumbea) has been studied in several range states in the Southwest Indian Ocean, however little information exists on populations in Madagascar. Here, we review available literature and describe a study on S. plumbea conducted between 2004 and 2013 on the west coast of Madagascar, involving boat-based field surveys in the southwest and northwest regions, and interview surveys with local fishers from villages along most of the west coast. Field surveys in the southwest region of Anakao/St. Augustine Bay revealed low encounter rates and mean group size, and markedly declining trends in both from 1999 to 2013. Conversely, in the northwest region around Nosy Be and Nosy Iranja, encounter rates were higher, as were mean group sizes, suggesting an apparently more abundant and less impacted population. Interview surveys revealed by-catch of coastal dolphins along the entire west coast, including S. plumbea, as well as other species. Directed hunting, including drive hunts of groups of dolphins, was reported primarily in the southern regions, in the range of the Vezo Malagasy ethnicity; however, there was evidence of hunting starting in one area in the northwest, where hunting dolphins is normally considered taboo for the predominant Sakalava ethnicity. Thus, the conservation status of S. plumbea in Madagascar appears to be spatially heterogeneous, with some areas where the local population is apparently more impacted than others. Conservation measures are recommended to mitigate further decline in the southwest of Madagascar, while protecting habitat and ensuring resilience in the northwest. © 2015 Elsevier Ltd.

Bolt L.M.,University of Toronto | Sauther M.L.,University of Colorado at Boulder | Cuozzo F.P.,University of North Dakota | Youssouf Jacky I.A.,University of Toliary
Folia Primatologica | Year: 2015

The ring-tailed lemur (Lemur catta) is a group-living strepsirrhine primate endemic to Madagascar that faces considerable predation pressure from aerial and terrestrial predators. This species engages in mobbing and vigilance behavior in response to predators, and has referential alarm vocalizations. Because L. catta is female dominant, less is known about the alarm calls of males. We tested 3 hypotheses for male antipredator vocalization behavior on L. catta at the Bezà Mahafaly Special Reserve in Madagascar: the predator confusion, group maintenance, and predation risk allocation hypotheses. We found support for 2 hypotheses. When a male L. catta made an antipredator call, other group members vocalized in response. Dominant males did not make alarm calls at higher rates than subordinate males. Predators were more abundant on the western side of Parcel 1, but an even greater number of antipredator vocalizations occurred in this area than predator abundance warranted. We show that male L. catta consistently participated in group-level antipredator vocalization usage in high-risk locations. Although female L. catta are known to hold the primary role in group defense, male L. catta are also key participants in group-wide behaviors that may confuse or drive away predators. © 2015 S. Karger AG, Basel.

Morteani G.,TU Munich | Kostitsyn Y.A.,RAS Vernadsky Institute of Geochemistry and Analytical Chemistry | Gilg H.A.,TU Munich | Preinfalk C.,Ludwig Maximilians University of Munich | Razakamanana T.,University of Toliary
International Journal of Earth Sciences | Year: 2013

The phlogopite, diopside, calcite, anhydrite and apatite pegmatites of Ampandrandava and Beraketa are examples for the many other pegmatites of similar silicocarbonatitic composition found in the Bekily and Betroka-Beraketa Precambrian belts of southern Madagascar. The two studied pegmatites and associated syenites crystallised from immiscible silicocarbonatitic and peralkaline syenitic melts in a time span between 515 and 504 Ma in the final extensional phase of the Panafrican continental collision and connected metamorphic/metasomatic event. Model TNd ages suggest that the melts were produced by partial melting of 3. 5 Ga partially evaporitic continental crust. The studied pegmatites and genetically associated syenitic rocks are very rare examples for crustal silicocarbonatitic melts generated in a Panafrican collisional setting. The overwhelming majority of carbonatites and associated peralkaline rocks are mantle derived, much poorer in phosphate and sulfate and found in a cratonic environment. In light of the present results, genetic models for other sulfate- and phosphate-rich magmatic rocks (e. g., phlogopite-apatite-calcite mineralisations in the Grenville-Hasting formation in Canada and in the Sludyanka group in Eastern Siberia) should be reevaluated. © 2012 Springer-Verlag Berlin Heidelberg.

Parga J.A.,University of Toronto | Sauther M.L.,University of Colorado at Boulder | Cuozzo F.P.,University of North Dakota | Jacky I.A.Y.,University of Toliary | Lawler R.R.,James Madison University
American Journal of Physical Anthropology | Year: 2012

In light of historical and recent anthropogenic influences on Malagasy primate populations, in this study ring-tailed lemur (Lemur catta) samples from two sites in southwestern Madagascar, Beza Mahafaly Special Reserve (BMSR) and Tsimanampetsotsa National Park (TNP), were evaluated for the genetic signature of a population bottleneck. A total of 45 individuals (20 from BMSR and 25 from TNP) were genotyped at seven microsatellite loci. Three methods were used to evaluate these populations for evidence of a historical bottleneck: M-ratio, mode-shift, and heterozygosity excess tests. Three mutation models were used for heterozygosity excess tests: the stepwise mutation model (SMM), two-phase model (TPM), and infinite allele model (IAM). M-ratio estimations indicated a potential bottleneck in both populations under some conditions. Although mode-shift tests did not strongly indicate a population bottleneck in the recent historical past when samples from all individuals were included, a female-only analysis indicated a potential bottleneck in TNP. Heterozygosity excess was indicated under two of the three mutation models (IAM and TPM), with TNP showing stronger evidence of heterozygosity excess than BMSR. Taken together, these results suggest that a bottleneck may have occurred among L. catta in southwestern Madagascar in the recent past. Given knowledge of how current major stochastic climatic events and human-induced change can negatively impact extant lemur populations, it is reasonable that comparable events in the historical past could have caused a population bottleneck. This evaluation additionally functions to highlight the continuing environmental and anthropogenic challenges faced by lemurs in southwestern Madagascar. Copyright © 2011 Wiley Periodicals, Inc.

Hubert N.,University of Reunion Island | Hubert N.,University of Perpignan | Meyer C.P.,Smithsonian Institution | Bruggemann H.J.,University of Reunion Island | And 6 more authors.
PLoS ONE | Year: 2012

Diversity in coral reef fishes is not evenly distributed and tends to accumulate in the Indo-Malay-Philippines Archipelago (IMPA). The comprehension of the mechanisms that initiated this pattern is in its infancy despite its importance for the conservation of coral reefs. Considering the IMPA either as an area of overlap or a cradle of marine biodiversity, the hypotheses proposed to account for this pattern rely on extant knowledge about taxonomy and species range distribution. The recent large-scale use of standard molecular data (DNA barcoding), however, has revealed the importance of taking into account cryptic diversity when assessing tropical biodiversity. We DNA barcoded 2276 specimens belonging to 668 coral reef fish species through a collaborative effort conducted concomitantly in both Indian and Pacific oceans to appraise the importance of cryptic diversity in species with an Indo-Pacific distribution range. Of the 141 species sampled on each side of the IMPA, 62 presented no spatial structure whereas 67 exhibited divergent lineages on each side of the IMPA with K2P distances ranging between 1% and 12%, and 12 presented several lineages with K2P distances ranging between 3% and 22%. Thus, from this initial pool of 141 nominal species with Indo-Pacific distribution, 79 dissolved into 165 biological units among which 162 were found in a single ocean. This result is consistent with the view that the IMPA accumulates diversity as a consequence of its geological history, its location on the junction between the two main tropical oceans and the presence of a land bridge during glacial times in the IMPA that fostered allopatric divergence and secondary contacts between the Indian and Pacific oceans. © 2012 Hubert et al.

Ratheesh-Kumar R.T.,Indian Institute of Science | Ishwar-Kumar C.,Indian Institute of Science | Windley B.F.,University of Leicester | Razakamanana T.,University of Toliary | And 2 more authors.
Gondwana Research | Year: 2015

The present study contributes new constraints on, and definitions of, the reconstructed plate margins of India and Madagascar based on flexural isostasy along the Western Continental Margin of India (WCMI) and the Eastern Continental Margin of Madagascar (ECMM). We have estimated the nature of isostasy and crustal geometry along the two margins, and have examined their possible conjugate structure. Here we utilize elastic thickness (Te) and Moho depth data as the primary basis for the correlation of these passive margins. We employ the flexure inversion technique that operates in spatial domain in order to estimate the spatial variation of effective elastic thickness. Gravity inversion and flexure inversion techniques are used to estimate the configuration of the Moho/Crust-Mantle Interface that reveals regional correlations with the elastic thickness variations. These results correlate well with the continental and oceanic segments of the Indian and African plates. The present study has found a linear zone of anomalously low-Te (1-5. km) along the WCMI (~1680. km), which correlates well with the low-Te patterns obtained all along the ECMM. We suggest that the low-Te zones along the WCMI and ECMM represent paleo-rift inception points of lithosphere thermally and mechanically weakened by the combined effects of the Marion hotspot and lithospheric extension due to rifting. We have produced an India-Madagascar paleo-fit representing the initial phase of separation based on the Te estimates of the rifted conjugate margins, which is confirmed by a close-fit correlation of Moho geometry and bathymetry of the shelf margins. The matching of tectonic lineaments, lithologies and geochronological belts between India and Madagascar provide an additional support for the present plate reconstruction. © 2014 International Association for Gondwana Research.

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