Anthropogenic landscape change and amphibian diversity in tropical montane biodiversity hotspots: insights from satellite remote sensing in the Madagascar highlands

The magnitude of anthropogenic landscape change in tropical montane biodiversity hotspots and its relationship with biodiversity is a global issue that remains ‘locked-in’ in the broad narrative of tropical change in Africa. Over a montane biodiversity hotspot of Madagascar highlands (Ankaratra Massif), we conducted analysis on land cover change with Landsat satellite sensor data to identify the magnitude of change (1995–2016) and on the habitat change–amphibian diversity relationship to understand links with biodiversity. The results evidenced that 17.8% of the biodiversity hotspot experienced change in land cover in only 20 years. That pressured the already threatened forests, particularly since 2005. Of the total forest area in 1995 (2062.7 ha), 21.5% was cleared by 2016 (1618.3 ha). Changes in forest cover followed a bidirectional pattern. While in the period 1995–2005, forests expanded at a rate of 2.0% year−1 (from 2062.7 to 2524.8 ha), the area declined between 2005 and 2016 at a rate of − 4.1% year−1, fourfold the rate reported nationally for Madagascar (− 1.1% year−1). Forest-to-shrubland transitions emerged as being of increasing concern to forest integrity. We identified a significant link between habitat change and amphibian diversity, but only for species richness. Counter to expectations, no significant relationship was found between species richness and deforestation rates, and between microendemism rates and any of the habitat change variables. Species richness responded to the spatiotemporal variability in vegetation dynamics represented by the standard deviation of the Normalized Differenced Vegetation Index (NDVI_std). Species richness was strongly negatively related to NDVI_std in the short-term (R2 = 0.91, p = 0.003) and long-term (R2 = 0.69, p = 0.03), increasing where the spatiotemporal variability in NDVI was lower. The magnitude of changes in this biodiversity hotspot suggests that region-specific assessments are necessary in the context of the tropical change narrative in Africa and should consider conservation policies tailored for local conditions. Reducing deforestation and land conversion rates through a management plan codesigned with local communities is urgent. Habitat change appears to impact on amphibian diversity by altering the functional attributes of the habitat and not just by reducing habitat extent. NDVI_std seems a relevant indirect metric for monitoring such change although other biophysical attributes obtained from satellite sensor data should be integrated and explored.info:eu-repo/semantics/acceptedVersio

Descriptions of two new Spinomantis frogs from Madagascar (Amphibia, Mantellidae), and new morphological data for S. brunae and S. massorum ; American Museum novitates, no. 3618

22 p. : ill. (some col.), map ; 26 cm.Includes bibliographical references (p. 20-21).New collections of Spinomantis frogs (Amphibia, Mantellidae, Mantellinae) have been made by us in northern Madagascar, and based on these collections we here describe two new species. One species, from northeastern Madagascar, has reduced dermal spines on the limbs and resembles S. massorum, but is diagnosed based on features including its shorter snout, proportionally longer hind limbs, reduced foot webbing, and different coloration. The other species, from the Tsaratanana Massif, is most similar to S. peraccae, but can be diagnosed based on features including its much larger body size, more extensive foot webbing and different coloration. We also redescribe two other poorly known species of Spinomantis: S. brunae and S. massorum. Both these rare species had been recently described based on a single and pair of type specimens respectively, and we here report on the morphology of new comparative material. For both the new and redescribed species, we summarize information on behavior, habits, individual variation, and distribution, and we also present a morphological identification key for the entire Spinomantis genus, which now includes 12 species. The new species from the Tsaratanana Massif is known only from a single site (Befosa River). Because this site is not protected within a reserve, we propose this forest be considered for inclusion within the ongoing protected area expansion program for Madagascar

Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar

International audienceAmphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians

Consistency of Published Results on the Pathogen Batrachochytrium dendrobatidis in Madagascar: Formal Comment on Kolby et al. Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar.

International audienceA recent paper by Kolby et al., surveying for Batrachochytrium dendrobatidis (Bd) and ranavirus in Madagascar, presents results for 508 amphibian specimens and 68 water bodies sampled during a 2-month period of the 2013–14 wet season. Kolby et al. did not detect Bd in any of the samples, presenting evidence that add to our understanding of Bd dynamics in Madagascar. Earlier in 2015, we published “Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar” in the journal Scientific Reports. We presented rigorous spatial and temporal surveillance data for 4,155 amphibians sampled across a 10-year period, and used two independent molecular diagnostics to demonstrate the occurrence of a molecular signature of Bd infection at multiple locations across the island. We focus here on solely the Bd results, which directly relate to our published study

The challenge of conserving amphibian megadiversity in Madagascar

Highly diverse and so far apparently untouched by emergent diseases, Malagasy frogs nevertheless are threatened by ongoing habitat destruction, making pro-active conservation actions especially important for preserving this unique, pre-decline, amphibian fauna

Habitat Fragments as Last Refuges for Amphibian Diversity

<p>In many largely deforested areas of Madagascar, small habitat fragments remain, which harbor significant amphibian diversity, and may allow the survival of yet undiscovered range-restricted species. So far no amphibian extinctions have been detected for Madagascar. A survey of the pictured forest fragment west of Ambatondrazaka in 2008 yielded 12 frog species, one of which is new to science.</p