Effects of turbidity and introduced tilapia (Oreochromis spp) on macrophytes and invertebrates in a shallow tropical lake

Tropical freshwater wetlands are subject to multiple stressors but there is little information on which stressors cause wetland degradation. Increased turbidity is considered a major cause of degradation, but the effects of introduced fish are often overlooked. Tilapia are frequently introduced in tropical regions, especially species in the genus Oreochromis, and the ecological effects of introducing tilapia are poorly studied. We used enclosure experiments in a shallow lake in Madagascar to assess the effects of tilapia and turbidity on macrophytes and benthic invertebrates, and to test management interventions designed to increase both. Tilapia at high and low stocking densities had negative effects on survival of Charophyte algae and water lilies, but no direct effect on benthic invertebrate abundance or diversity. Invertebrate abundance was highest on submerged Charophytes, so herbivory by tilapia indirectly affected invertebrates. Turbidity affected Charophyte survival, and abundance and diversity of non-Dipteran insects. As a complication, tilapia may increase turbidity by re-suspending the lake sediment. Our results suggest that herbivory by tilapia is a plausible cause of the removal of macrophytes from the lake and an impediment to their re-establishment. Tilapia are widely introduced in tropical areas as a food resource. Our results demonstrate serious consequences to these introductions

Comportement De Territorialité De Propithecus Deckenii Dans Les Aires Protégées Complexe Tsimembo Manambolomaty Et Mandrozo

This study aims to understand the behavior territoriality of the lemur Decken's Sifaka Propithecus deckenii in the Protected Areas (PAs) Complexe Tsimembo Manambolomaty and Mandrozo in the central-west of Madagascar between November 2017 and April 2018, and between July and October 2018. The continuous focal animal sampling method was used to monitor eight groups of Sifakas, two groups of the intact habitat and two groups from the disturbed habitat in each PA. Scent marking frequencies per focal groups differs between the two habitats types and is influenced by sex in favor of males. Season does not impacted this activity. The home range (define by MCP and 95% Kernel density estimate) and core area varies between monitored groups and the daily path length can reach 234 ± 98 m to 362 ± 110 m. These parameters are not influenced by season and habitat types. However, the intensity of territory use does not have any variation among the studied groups. The mean average « defensibility index » value for P. deckenii is 1.74 ± 0.70 (n = 8). The studied species has ability to adjust their territorial behavior, despite the degradation of habitat in sustainable use zone

Protected area surface extension in Madagascar: Do endemism and threatened species remain useful criteria for site selection?

The ‘hotspot approach’ considers that endemism and threatened species are key factors in protected area designation. Three wetland and forest sites have been proposed to be included into Madagascar’s system of protected areas (SAPM – Système des Aires Protégées de Madagascar). These sites are Manambolomaty (14,701 ha) and Mandrozo (15,145 ha) in the west and Bemanevika (37,041 ha) in the north. Biodiversity inventories of these three sites recorded 243 endemic species comprised of 44 reptiles, 54 amphibians, 104 birds, 23 small mammals, 17 lemurs and one fish. Of these 243 species, 30 are threatened taxa comprising two Critically Endangered (CR), 11 Endangered (EN) and 17 Vulnerable (VU) species. The long term ecological viability of these sites has been shown by population stability of the two Critically Endangered flagship species, the Madagascar fish eagle (Haliaeetus vociferoides) in Manambolomaty and Mandrozo and the recently rediscovered Madagascar pochard (Aythya innotata) in Bemanevika. Other threatened species and high biological diversity also justifies their inclusion into Madagascar’s SAPM.RÉSUMÉL’endémisme et les espèces menacées constituent les éléments clef pour la création des aires protégées. Trois zones humides de Madagascar ainsi que leurs forêts avoisinantes sont proposées pour la protection sous le nouveau système des aires protégées malgaches connu sous le sigle SAPM (Système d’Aires Protégées de Madagascar) : Manambolomaty (14.701 ha) et Mandrozo (15.145 ha) à l’Ouest et Bemanevika (37.041 ha) dans le Nord. Les inventaires biologiques entrepris dans ces trois sites ont montré que 243 espèces y sont endémiques, avec 44 reptiles, 54 amphibiens, 104 oiseaux, 23 petits mammifères, 17 lémuriens et un poisson. Parmi ces 243 espèces, 30 sont menacées d’extinction avec deux qui sont en danger critique d’extinction (CR), 11 en danger (EN) et 17 vulnérables (VU). La survie écologique à long terme de ces sites a été avérée avec la découverte de la stabilité des populations des deux espèces indicatrices en danger critique d’extinction que sont le Pygargue de Madagascar (Haliaeetus vociferoides) à Manambolomaty et Mandrozo et une espèce récemment redécouverte, le Fuligule de Madagascar (Aythya innotata) à Bemanevika. La stabilité de plusieurs autres espèces menacées ainsi que la diversité biologique de ces sites justifient leur inclusion dans le SAPM. Les sept associations locales, deux à Manambolomaty, deux à Bemanevika et trois à Mandrozo, ont supporté le programme de suivi de ces sites ainsi que de ces espèces indicatrices en montrant ainsi leur engagement dans le processus de création des aires protégées. Le Peregrine Fund a travaillé dans ces sites en vue de mettre en synergie ses objectifs de conservation avec le développement socio-économique local

Nesting biology and food habits of the Peregrine Falcon Falco peregrinus radama in the south-west and central plateau of Madagascar

We studied nesting biology, behaviour, and diet of the Peregrine Falcon Falco peregrinus radama in Madagascar during two breeding seasons at Tsimanampetsotsa Natural Reserve in the south-west (n = 2 nests) and at Tritriva Lake (n = 1 nest) on the central plateau from July to November 1999 and June to October 2000, respectively. Pair formation took place in May at Tritiva and in June at Tsimanampetsotsa. Mating periods spanned 75 days in the south-west and 43 days on the central plateau. Eggs were laid during July on the high plateau and in August in the south-west. The incubation period at the two nests was 33 and 35 days, respectively. Five young hatched in two nests, three on the central plateau in August and a minimum of two in the south-west in September. Two young fledged successfully at 42 days of age at the south-west nest and the three young at the high plateau succumbed to unknown causes. The two fledged young dispersed at 64 days of age. The Peregrine Falcon diet in Madagascar varied between the two sites: in the south-west 100% (n = 353 birds; 19 species) of identified prey was composed of native birds and 99% (n = 94; 2 species) of identified prey at the central plateau site was almost exclusively domestic chickens Gallus gallus. Ostrich 2007, 78(1): 7–1

Nest characteristics of Yellow-billed Kites Milvus aegyptius in the Manambolomaty Lakes Complex, western Madagascar

We studied the nesting biology of Yellow-billed Kites Milvus aegyptius in the Manambolomaty Lakes Complex of western Madagascar during 2002 and 2003. We recorded 64 nesting attempts. In 2003, 33% (n = 39 nests) of the occupied nests were from the previous breeding season. The average time for building new nests was 57 d (SD = 30.6; range 18–83 d; n = 5 nests). Males contributed 75% of the nesting material. All nests were built of dry sticks and other unique nest materials. During the nest building period, 83% (n = 241) of the dry sticks were collected less than 50 m from the nest tree. The unique nest material was collected from the ground and delivered to the nest 10 d prior to egg-laying. The average distance between neighbouring nests was 264 m (SD = 270.8, range = 26–1 081, n = 33 nests). Yellow-billed Kite nests averaged 9.6 m (SD = 2.4; range 4–14.8 m; n = 64 nests) above ground level and 64% (41 of 64 nests) were in tamarind trees (Tamarindus indica). Nest trees mean DBH was 63.9 cm (SD = 28.1, range 25–200 cm; n = 64 nests).Keywords: Manambolomaty Lakes Complex, Milvus aegyptius, nest characteristics, western Madagascar, Yellow-billed KiteOSTRICH 2013, 84(1): 79–8

Effects of turbidity and introduced tilapia (

Tropical freshwater wetlands are subject to multiple stressors but there is little information on which stressors cause wetland degradation. Increased turbidity is considered a major cause of degradation, but the effects of introduced fish are often overlooked. Tilapia are frequently introduced in tropical regions, especially species in the genus Oreochromis, and the ecological effects of introducing tilapia are poorly studied. We used enclosure experiments in a shallow lake in Madagascar to assess the effects of tilapia and turbidity on macrophytes and benthic invertebrates, and to test management interventions designed to increase both. Tilapia at high and low stocking densities had negative effects on survival of Charophyte algae and water lilies, but no direct effect on benthic invertebrate abundance or diversity. Invertebrate abundance was highest on submerged Charophytes, so herbivory by tilapia indirectly affected invertebrates. Turbidity affected Charophyte survival, and abundance and diversity of non-Dipteran insects. As a complication, tilapia may increase turbidity by re-suspending the lake sediment. Our results suggest that herbivory by tilapia is a plausible cause of the removal of macrophytes from the lake and an impediment to their re-establishment. Tilapia are widely introduced in tropical areas as a food resource. Our results demonstrate serious consequences to these introductions

Traditional uses of the plants consumed by Propithecus deckenii (Peters, 1870) in Mandrozo Protected Area, western Madagascar

This study focused on the diet of Decken’s sifaka (Propithecus deckenii) and was carried out in Mandrozo Protected Area (MPA), in western Madagascar. The main objective was to identify the plants consumed by sifakas and their traditional uses by the local people within and surrounding MPA. For this purpose, we observed and recorded the feeding behavior of four groups of sifakas in two forest fragments (Andapabe and Ampiliravao), during two periods: from March to April 2018 for the wet season and from September to October 2020 for the dry season, using the Focal Animal Sampling method. Sifakas consumed 37 plant species belonging to 20 families and 31 genera and they ate mainly the plant leaves. We found that the sifaka’s diet is more diversified during wet season. We also interviewed 168 local persons from eight villages and recorded their ethnobotanical knowledge on the plant species eaten by sifakas. Local people utilized 70% (n=26) of the plant species eaten by sifakas. Five categories of human uses were recorded: house construction and tools for domestic use, phytotherapy, making of handicrafts, as food sources and traditional culture. Among these, the construction of houses and tools for domestic use and traditional medicine constitute the main mentioned human uses by the queried locals. For the indigenous people, three species of trees: Dalbergia humbertii, Tamarindus indica and Cedrelopsis grevei were used as part of their habits and customs