Alaotra wetlands, Madagascar (photo: Pina Lammers); Madagascar Conservation & Development

Lake Alaotra wetlands: how long can Madagascar´s most important rice and fish production region withstand the anthropogenic pressure?

Pina L. Lammers, Torsten Richter, Patrick O. Waeber, Jasmin Mantilla-Contreras

Abstract


The Alaotra wetlands represent the biggest lake and wetland complex in Madagascar and are home of several endemic species. The region constitutes the largest rice production area and inland fishery of Madagascar. Rice and fish are the main local sources of income. While the population has increased fivefold during the last 40 years, the growing need for resources is continuously increasing the pressure on the wetland system. In this study, vegetation and water parameters were collected within three sites differing by level of degradation in order to evaluate the current ecological state of the wetland. The results show that high levels of ongoing anthropogenic disturbance are favoring the formation of a new plant community in the fringe area of the marsh belt. This area is now dominated by invasive species such as the water hyacinth (Eichhornia crassipes) which shows a mean coverage up to 53% and water ferns (Salvinia spp.) with a mean coverage up to 31.4%. Lake water levels were very low and decreased during the dry season to a mean level of only 3 cm in the littoral zone. Signs of eutrophication like hypoxia (mean saturation of only 22%), increased phosphate concentrations (1.18 mg L-1 ) and black colored, foul smelling water were observed. Under a likely scenario of growing anthropogenic pressures, it remains unclear what the current trends will bring for the wetland’s future.

RÉSUMÉ

La zone humide de l’Alaotra représente le plus grand lac et complexe de zones humides de Madagascar hébergeant plusieurs espèces endémiques. La région constitue la première production de riz et de pêche dulcicole de l’île. Le riz et les ressources piscicoles sont les principales sources de revenus locaux. L’effectif de la population humaine locale a été quintuplé au cours des dernières 40 années et les besoins en ressources ont augmenté en conséquence de sorte que les pressions sur la zone humide ont été exacerbées. Dans cette étude, des paramètres portant sur la végétation et l’eau du lac ont été collectés dans trois sites qui diffèrent par le niveau de dégradation pour évaluer l’état écologique actuel de la zone humide. Les résultats montrent que le niveau élevé des perturbations anthropiques favorise la formation d’une nouvelle communauté végétale sur la ceinture du marais. Cette zone est dominée par des espèces de plantes envahissantes à l’exemple de la jacinthe d’eau (Eichhornia crassipes) dont la couverture moyenne est de 53% et de la fougère d’eau (Salvinia spp.) avec une couverture moyenne de 31,4%. Les niveaux du lac sont bas et diminuent jusqu’à 3 cm de moyenne dans la zone littorale pendant la saison sèche. Des signes d’eutrophisation comme l’hypoxie (saturation moyenne de 22%), l’augmentation de la concentration de phosphate (1,18 mg L-1 ) et la présence d’eau de couleur noire et nauséabonde ont été observés. Dans un possible scénario avec une augmentation des pressions humaines, les tendances actuelles restent difficiles à comprendre pour l’avenir de la zone humide.


Keywords


Alaotra wetlands; human disturbance; invasive species; eutrophication; drawdown

Full Text:

PDF

References


Abdi, H. 2010. Holm’s sequential Bonferroni procedure. In: Encyclopedia of Research Design. N. J. Salkind (ed.), pp 1–8. Sage Publication, Thousand Oaks, California.

Adams, C. S., Boar, R. R., Hubble, D. S., Gikungu, M., Harper, D. M. et al. 2002. The dynamics and ecology of exotic tropical species in floating plant mats: Lake Naivasha, Kenya. Developments in Hydrobiology 168: 115–122. http://dx.doi.org/10.1007/978-94-017-2031-1_11

Andrianandrasana, H. T., Randriamahefasoa, J., Durbin, J., Lewis, R. E. and Ratsimbazafy, J. H. 2005. Participatory ecological monitoring of the Alaotra wetlands in Madagascar. Biodiversity Conservation 14, 11: 2757–2774. http://dx.doi.org/10.1007/s10531-005-8413-y

Araoye, P. A. 2009. The seasonal variation of pH and dissolved oxygen (DO2) concentration in Asa lake Ilorin, Nigeria. International Journal of Physical Sciences 4, 5: 271–274.

Arhonditsis, G., Brett, M. T. and Frodge, J. 2003. Environmental control and limnological impacts of a large recurrent spring bloom in Lake Washington, USA. Environmental Management 31, 5: 603–618. http://dx.doi.org/10.1007/s00267-002-2891-4

Bailey, R. G. and Litterick, M. R. 1993. The macroinvertebrate fauna of water hyacinth fringes in the Sudd swamps (River Nile, southern Sudan). Hydrobiologia 250, 2: 97–103. http://dx.doi.org/10.1007/BF00008231

Bakoariniaina, L. N., Kusky, T. and Raharimahefa, T. 2006. Disappearing Lake Alaotra: Monitoring catastrophic erosion, waterway silting, and land degradation hazards in Madagascar using Landsat imagery. Journal of African Earth Sciences 44, 2: 241–252. http://dx.doi.org/10.1016/j.jafrearsci.2005.10.013

Bland, J. M. and Altman, D. G. 1995. Multiple significance tests: the Bonferroni method. British Medical Journal 310: 170. http://dx.doi.org/10.1136/bmj.e509

Calvert, P. 2002. Water Hyacinth Control and Possible Uses. Technical Brief. International Technology Development Center, United Kingdom.

Chale, F. M. 2011. Preliminary studies on the ecology of Mbasa (Opsaridium microlepis (Gunther)) in Lake Nyasa around the Ruhuhu River. Journal of Ecology and the Natural Environment 3, 2: 58–62.

Chang, K. H., Imai, H., Ayukawa, K., Sugahara, S., Nakano, S. I. and Seike, Y. 2013. Impact of improved bottom hypoxia on zooplankton community in shallow eutrophic lake. Knowledge and Management of Aquatic Ecosystems 408, 3: 1–8. http://dx.doi.org/10.1051/kmae/2013038

Chaperon, P., Danloux, J. and Ferry, L. 1993. Fleuves et Rivières de Madagascar. Collection Monographie Hydrologique no.10, ORSTOM, Paris, France.

Charles, H. and Dukes, J. S. 2007. Impacts of invasive species on ecosystem services. In: Biological Invasions, W. Nentwid (ed.), pp 217–237. Springer, Berlin.

Chowdhary, S. and Sharma, K. K. 2013. Eichhornia crassipes as a most preferred habitat for macrobenthic invertebrates. Journal of Pharmaceutical and Scientific Innovation 2, 4: 70–72. http://dx.doi.org/10.7897/2277-4572.02458

Copsey, J. A., Jones, J. P., Andrianandrasana, H., Rajaonarison, L. H. and Fa, J. E. 2009a. Burning to fish: local explanations for wetland burning in Lac Alaotra, Madagascar. Oryx 43, 3: 403–406. http://dx.doi.org/10.1017/S0030605309000520

Copsey, J. A., Rajaonarison, L. H., Randriamihamina, R and Rakotoniaina, L. J. 2009b. Voices from the marsh: Livelihood concerns of fishers and rice cultivators in the Alaotra wetland. Madagascar Conservation & Development 4, 1: 25–30. http://dx.doi.org/10.4314/mcd.v4i1.44008

Dudgeon, D., Arthington, A. H., Gessner, M. O., Kawabata, Z. I., Knowler, D. J. et al. 2006. Freshwater biodiversity: importance, threats, status and conservation challenges. Biological Reviews 81, 2: 163–182. http://dx.doi.org/10.1017/S1464793105006950

Dugan, P. J. 1990. Wetland Conservation: A Review of Current Issues and Required Action. IUCN, Gland, Switzerland.

Durbin, J., Funk, S. M., Hawkins, F., Hills, D. M., Jenkins, P. D. et al. 2010. Investigations into the status of a new taxon of Salanoia (Mammalia: Carnivora: Eupleridae) from the marshes of Lac Alaotra, Madagascar. Systematics and Biodiversity 8, 3: 341–355. http://dx.doi.org/10.1080/14772001003756751

Dusart, J. 1963. Contribution à l'étude de l'adaptation des Tilapia (Pisces, Cichlidae) à la vie en milieu mal oxygéné. Hydrobiologia 21, 3–4: 328–341. http://dx.doi.org/10.1007/BF01025947

Efitre, J., Chapman, L. J., and Makanga, B. 2011. The inshore benthic macroinvertebrates of Lake Nabugabo, Uganda: seasonal and spatial patterns. African Zoology 36, 2: 205–216.

Ekau, W., Auel, H., Pörtner, H. O. and Gilbert, D. 2010. Impacts of hypoxia on the structure and processes in the pelagic community (zooplankton, macro-invertebrates and fish). Biogeosciences 7: 1669–1699. http://dx.doi.org/10.5194/bg-7-1669-2010

El-Shabrawy, G. M. and Al-Ghanim, K. A. 2012. Aquatic Habitats in Africa. Animal Resources in Africa and Their Biodiversity. Encyclopedia of Life Supporting Systems (EOLSS) UNESCO.

Ferry, L., Mietton, M., Robison, L. and Erismann, J. 2009. Alaotra Lake (Madagascar) – Past, Present and Future. Annals of Geomorphology 53, 3: 299–318. http://dx.doi.org/10.1127/0372-8854/2009/0053-0299

Fisher, J. and Acreman, M. C. 2004. Wetland nutrient removal: a review of the evidence. Hydrology and Earth System Sciences 8, 4: 673–685. http://dx.doi.org/10.5194/hess-8-673-2004

Ganf, G. G. 1974. Rates of oxygen uptake by the planktonic community of a shallow equatorial lake (Lake George, Uganda). Oecologia 15, 1: 17–32. http://dx.doi.org/10.1007/BF00345226

Gaudet, J. J. 1977. Natural drawdown on Lake Naivasha, Kenya, and the formation of papyrus swamps. Aquatic Botany 3: 1–47. http://dx.doi.org/10.1016/0304-3770(77)90002-X

Gaudet, J. J. and Muthuri, F. M. 1981. Nutrient relationships in shallow water in an African lake, Lake Naivasha. Oecologia 49, 1: 109–118. http://dx.doi.org/10.1007/BF00376907

Geron, C., Owen, S., Guenther, A., Greenberg, J., Rasmussen, R. et al. 2006. Volatile organic compounds from vegetation in southern Yunnan Province, China: Emission rates and some potential regional implications. Atmospheric Environment 40, 10: 1759–1773. http://dx.doi.org/10.1016/j.atmosenv.2005.11.022

Gichuki, J., Omondi, R., Boera, P., Okorut, T., Matano, A. S. et al. 2012. Water Hyacinth Eichhornia crassipes (Mart.) Solms-Laubach dynamics and succession in the Nyanza Gulf of Lake Victoria (East Africa): Implications for Water Quality and Biodiversity Conservation. The Scientific World Journal 2012: #106429. http://dx.doi.org/10.1100/2012/106429

Gilinsky, E. 1984. The role of fish predation and spatial heterogeneity in determining benthic community structure. Ecology 65: 455–468. http://dx.doi.org/10.2307/1941408

Grieshaber, M. K., Hardewig, I., Kreutzer, U. and Pörtner, H. O. 1994. Physiological and metabolic responses to hypoxia in invertebrates. Reviews of Physiology, Biochemistry and Pharmacology 125: 43–147. http://dx.doi.org/10013/epic.11652

Guillera–Arroita, G., Lahoz–Monfort, J. J., Milner–Gulland, E. J. and Young, R. P. 2010. Monitoring and conservation of the critically endangered Alaotran gentle lemur Hapalemur alaotrensis. Madagascar Conservation & Development 5: 103–109. http://dx.doi.org/10.4314/mcd.v5i2.63140

Harper, D. M., Harper, M. M., Virani, M. A., Smart, A., Childress, R. B. et al. 2002. Population fluctuations and their causes in the African Fish Eagle (Haliaeetus vocifer (Daudin)) at Lake Naivasha, Kenya. Hydrobiologia 488: 171–180. http://dx.doi.org/10.1023/A:1023390800872

Hawkins, A. F. A., Andriamasimanana, R., Seing, S. T. and Rabeony, Z. 2000. The sad story of the Alaotra Little Grebe Tachybaptus rufolavatus. Bulletin of the African Bird Club 7, 2: 115–117.

Hill, L. G. 1969. Reactions of the American eel to dissolved oxygen tensions. Texas Journal of Science 20, 4: 305–313.

Hill, R., Webb, G. J. and Smith, A. M. 1987. Floating vegetation mats on a floodplain billabong in the Northern Territory of Australia. Hydrobiologia 150, 2: 153–164. http://dx.doi.org/10.1007/BF00006663

Howard-Williams, C. 1975. Vegetation changes in a shallow African lake: Response of the vegetation to a recent dry period. Hydrobiologia 47, 3–4: 381–398. http://dx.doi.org/10.1007/BF00039584

Howard-Williams, C. and Gaudet, J. J. 1985. The structure and functioning of African swamps. In: The ecology and management of African wetland vegetation. Denny, P. (ed.), pp 153–175. Springer, Netherlands.

Howard–Williams, C. and Lenton, G. 1975. The role of the littoral zone in the functioning of a shallow tropical lake ecosystem. Freshwater Biology 5, 5: 445–459. http://dx.doi.org/10.1111/j.1365-2427.1975.tb00147.x

Howard-Williams, C. and Thompson, K. 1985. The conservation and management of African wetlands. In: The ecology and management of African wetland vegetation. P. Denny (ed.), pp 203–230. Springer, Netherlands.

Huston, M. 1979. A general hypotheses of species diversity. American Naturalist 113, 1: 81–101.

INSTAT. 2013. Population et démographie de Madagascar. Institut National de la Statistique. http://www.instat.mg accessed 26 January 2014.

Jafari, N. 2010. Ecological and socio-economic utilization of water hyacinth (Eichhornia crassipes Mart Solms). Journal of Applied Sciences and Environmental Management 14, 2: 43–49. http://dx.doi.org/10.4314/jasem.v14i2.57834

Junk, W. J. 2002. Long-term environmental trends and the future of tropical wetlands. Environmental Conservation 29, 4: 414–435. http://dx.doi.org/10.1017/S03768922902000310

Katagira, F., Kyamanywa, S., Tenywa, J. S., Rajabu, C. A., Sombe, D. and Ndunguru, J. 2011. Impact of interspecific competition by compatriot aquatic weeds on water hyacinth Eichhornia crassipes (Martius) Solms growth and development in the Kagera River. International Journal of Biodiversity and Conservation 3, 8: 345–357.

Kebede, S., Travi, Y., Alemayehu, T. and Marc, V. 2006. Water balance of Lake Tana and its sensitivity to fluctuations in rainfall, Blue Nile basin, Ethiopia. Journal of Hydrology 316, 1–4: 233–247. http://dx.doi.org/10.1016/j.jhydrol.2005.05.011

Kusky, T. M., Toraman, E., Raharimahefa, T. and Rasoazanamparany, C. 2010. Active tectonics of the Alaotra–Ankay Graben System, Madagascar: Possible extension of Somalian–African diffusive plate boundary? Gondwana Research 18, 2: 274-294. http://dx.doi.org/10.1016/j.gr.2010.02.003

Lambert, E., Dutartre, A., Coudreuse, J. and Haury, J. 2010. Relationships between the biomass production of invasive Ludwigia species and physical properties of habitats in France. Hydrobiologia 656, 1: 173–186. http://dx.doi.org/10.1007/s10750-010-0440-3

Lamers, L. P. M., Tomassen, H. B. M. and Roelofs, J. G. M. 1998. Sulfate induced eutrophication and phytotoxicity in freshwater wetlands. Environmental Science and Technology 32, 2: 199–205. http://dx.doi.org/10.1021/es970362f

Lamers, L. P. M., Falla, S. J., Samborska, E. M., Van Dulken, I. A. R., Van Hengstum, G. and Roelofs, J. G. M. 2002. Factors controlling the extent of eutrophication and toxicity in sulfate-polluted freshwater wetlands. Limnology and Oceanography 47, 2: 585–593. http://dx.doi.org/10.4319/lo.2002.47.2.05

Larsson, P. and Lampert, W. 2011. Experimental evidence of a low-oxygen refuge for large zooplankton. Limnology and Oceanography 56, 5: 1682–1688. http://dx.doi.org/10.4319/lo.2011.56.5.1682

Lévêque, C. 1997. Biodiversity Dynamics and Conservation: The Freshwater Fish of Tropical Africa. Cambridge University Press, Cambridge.

Londo, G. 1976. The decimal scale for releves of permanent quadrats. Vegetatio 33, 1: 61–64. http://dx.doi.org/10.1007/BF00055300

Lung'Ayia, H., Sitoki, L. and Kenyanya, M. 2001. The nutrient enrichment of Lake Victoria (Kenyan waters). Hydrobiologia 458, 1–3: 75–82. http://dx.doi.org/10.1023/A:1013128027773

Mailu, A. M. 2001. Preliminary assessment of the social, economic and environmental impacts of water hyacinth in the Lake Victoria Basin and the status of control. In: Biological and Integrated Control of Water Hyacinth Eichhornia crassipes, pp 130–139. ACIAR Proceedings N. 102, Australia.

Mangas–Ramirez, E. and Elias–Gutierrez, M. 2004. Effect of mechanical removal of water hyacinth (Eichhornia crassipes) on the water quality and biological communities in a Mexican reservoir. Journal of Aquatic Health and Management 7, 1: 161–168. http://dx.doi.org/10.1080/14634980490281597

Marcus, N. H. 2001. Zooplankton: responses to and consequences of hypoxia. In: Coastal and Estuarine Studies: Coastal Hypoxia, Consequences for Living Resources and Ecosystems. N. N. Rabalais and R. E. Turner (eds.), pp 49–60. American Geophysical Union, Washington, DC. http://dx.doi.org/10.1029/CE058p0049

Masifwa, W. F., Twongo, T. and Denny, P. 2001. The impact of water hyacinth, Eichhornia crassipes (Mart) Solms on the abundance and diversity of aquatic macroinvertebrates along the shores of northern Lake Victoria, Uganda. Hydrobiologia 452, 1–3: 79–88. http://dx.doi.org/10.1023/A:1011923926911

Miller, D., Poucher, S. and Coiro, L. 2002. Determination of lethal dissolved oxygen levels for selected marine and estuarine fishes, crustaceans, and a bivalve. Marine Biology 140, 2: 287–296. http://dx.doi.org/10.1007/s002270100702

Mitsch, W. J. and Gosselink, J. G. 2000. The value of wetlands: importance of scale and landscape setting. Ecological Economics 35, 1: 25–33. http://dx.doi.org/10.1016/S0921-8009(00)00165-8

Moreau, J. 1979. Le lac Alaotra à Madagascar: cinquante ans d’aménagement des pêches. Cahiers ORSTOM. Série Hydrobiologie. ORSTOM, Paris.

Moreau, J. 1980. Essai d’application au lac Alaotra (Madagascar) d’un modèle d’étude de pêcheries pour les plaines d’inondation intertropicales. Cahier ORSTOM. Hydrobiologie 13, 1–2: 83–91.

Moss, B., Kosten, S., Meerhof, M., Battarbee, R., Jeppesen, E. et al. 2011. Allied attack: climate change and eutrophication. Inland Waters 1, 2: 101–105.

Mutschler, T. 2003. Lac Alaotra. In: The Natural History of Madagascar. S. M. Goodman and J. P. Benstead (eds.), pp 1530–1534. The University of Chicago press, Chicago.

Mutschler, T. and Feistner, A. T. C. 1995. Conservation status and distribution of the Alaotran gentle lemur Hapalemur griseus alaotrensis. Oryx 29, 4: 267–274. http://dx.doi.org/10.1017/S0030605300021268

Mutschler, T., Feistner, A. T. C. and Nievergelt, C. M. 1998. Preliminary field data on group size, diet and activity in the Alaotran gentle Lemur Hapalemur griseus alaotrensis. Folia Primatologica 69, 5: 325–330. http://dx.doi.org/10.1159/000021647

Njambuya, J. and Triest, L. 2010. Comparative performance of invasive alien Eichhornia crassipes and native Ludwigia stolonifera under non limiting nutrient conditions in Lake Naivasha, Kenya. Hydrobiologia 656: 221–231. http://dx.doi.org/10.1007/s10750-010-0430-5

Nievergelt, C. M., Mutschler, T., Feistner, A. T. C. and Woodruff, D. S. 2002. Social system of the Alaotran gentle lemur (Hapalemur griseus alaotrensis). American Journal of Primatology 57, 4: 157–176. http://dx.doi.org/10.1002/ajp.10046

Njiru M., Othina, A., Getabu, A., Tweddle, D. and Cowx, I. G. 2002. Is the infestation of Water hyacinth, Eichhornia crassipes a blessing to Lake Victoria? In: Management and Ecology of the Lake Reservoirs Fisheries. I. G. Cowx (ed.), pp 255–63. Oxford Fishing News Books. Blackwell Science, Tokyo.

Ogutu-Ohwayo, R., Hecky, R. E., Cohen, A. S. and Kaufman, L. 1997. Human impacts on the African great lakes. Environmental Biology of Fishes 50, 2: 117–131. http://dx.doi.org/10.1023/A:1007320932349

Pausas, J. G. and Austin, M. P. 2001. Patterns of plant species richness in relation to different environments: An appraisal. Journal of Vegetation Science 12, 2: 153–166. http://dx.doi.org/10.2307/3236601

Payne, A. I. 1986. The Ecology of Tropical Lakes and Rivers. Wiley, Chichester, U.K.

Peck, D. 2004. Madagascar designates its third Ramsar Site. Lemur News 9: 3.

Petr, T. 2000. Interactions between Fish and Aquatic Macrophytes in Inland Waters. A review. FAO Fisheries, Technical Paper 396, Rome.

Philippart, J. C. and Ruwet, J. C. 1982. Ecology and distribution of tilapias. In: ICLARM Conference Proceedings. R. S. V. Pullin and R. H. Lowe-Mc Connell (eds.), pp 15–59. Manila.

Pidgeon, M. 1996. An ecological survey of Lake Alaotra and selected wetlands of central and eastern Madagascar in analyzing the demise of Madagascar pochard Aythya innotata. WWF/Missouri Botanical Garden, St. Louis.

Plan Régional de Développement. 2005. Région Alaotra-Mangoro, Province Autonome de Toamasina. Unpubl. Report.

Prepas, E. E. and Charette, T. 2003. Water Bodies: Causes, Concerns, Controls. In: Treatise on Geochemistry. H. D. Holland, K. K. Turekian, (eds.), pp 311–331. Elsevier. http://dx.doi.org/10.1016/B0-08-043751-6/09169-6

Qureshi, N. A. and Rabalais, N. N. 2001. Distribution of zooplankton on a seasonally hypoxic continental shelf. In: Coastal and Estuarine Studies: Coastal Hypoxia, Consequences for Living Resources and Ecosystems. N. N. Rabalais and R. E. Turner (eds.), pp 61–76. American Geophysical Union, Washington, DC. http://dx.doi.org/10.1029/CE058p0061

Rakotoarisoa, T. F., Waeber, P. O., Richter, T. and Mantilla-Contreras, J. 2015. Water hyacinth (Eichhornia crassipes), any opportunities for the Alaotra wetlands and livelihoods? Madagascar Conservation & Development. 10, S3128–136. http://dx.doi.org/10.4314/mcd.v10i3s.5

Ralainasolo, F. B. 2004. Action des effets anthropiques sur la dynamique de la population de Hapalemur griseus alaotrensis ou Bandro dans son habitat naturel. Lemur News 9: 32–35.

Ralainasolo, F. B., Waeber, P. O., Ratsimbazafy, J., Durbin, J. and Lewis, R. 2006. The Alaotra gentle lemur: Population estimation and subsequent implications. Madagascar Conservation & Development 1, 1: 9–10. http://dx.doi.org/10.4314/mcd.v1i1.44044

Ramsar. 2007. Signatories and Sites http://www.ramsar.org accessed 15 January 2014.

Ranarijaona, H. L. T. 2007. Concept de modèle écologique pour la zone humide Alaotra. Madagascar Conservation & Development 2, 1: 25–42. http://dx.doi.org/10.4314/mcd.v2i1.44128

Ratsimbazafy, J. H., Ralainasolo, F. B., Rendigs, A., Mantilla-Contreras, J., Andrianandrasana, H. et al. 2013. Gone in a puff of smoke? Hapalemur alaotrensis at great risk of extinction. Lemur News 17: 14–18.

Reinthal, P. N. and Stiassny, M. L. J. 1991. The freshwater fishes of Madagascar: a study of an endangered fauna with recommendations for a conservation strategy. Conservation Biology 5, 2: 231–243. http://dx.doi.org/10.1111/j.1523-1739.1991.tb00128

Rendigs, A., Reibelt, L. M., Ralainasolo, F. B., Ratsimbazafy, J. H. and Waeber, P. O. 2015. Ten years into the marshes – Hapalemur alaotrensis conservation, one step forward and two steps back? Madagascar Conservation & Development 10, S1: 13–20. http://dx.doi.org/10.4314/mcd.v10i1.s3

René de Roland, L. A., Thorstrom, R., Razafimanjato, G., Rakontondratsima, M. P. H. and The Seing Sam. 2009. Surveys, distribution and current status of the Madagascar Harrier Circus macrosceles in Madagascar. Bird Conservation International 19, 4: 309–322. http://dx.doi.org/10.1017/S095927090900817X

Roggeri, H. 1995. Tropical Freshwater Wetlands: A Guide to Current Knowledge and Sustainable Management. Kluwer Academic Publishers, Dordrecht, Netherlands.

Roman, M. R., Pierson, J. J., Kimmel, D. G., Boicourt, W. C. and Zhang, X. 2012. Impacts of hypoxia on zooplankton spatial distributions in the northern Gulf of Mexico. Estuaries and coasts 35, 5:1261–1269. http://dx.doi.org/10.1007/s12237-012-9531-x

Rommens, W., Maes, J., Dekeza, N. and Ingelbrecht, P. 2003. The impact of water hyacinth (Eichhornia crassipes) in a eutrophic subtropical impoundment (Lake Chivero, Zimbabwe). I. Water Quality. Fundamental and Applied Limnology 158, 3: 373–388. http://dx.doi.org/10.1127/0003-9136/2003/0158-0373

Sambasiva Rao, A. 1988. Evapotranspiration rates of Eichhornia crassipes (Mart.) Solms, Salvinia molesta ds Mitchell and Nymphaea lotus (L.) Willd. Linn. in a humid tropical climate. Aquatic Botany 30, 3: 215–222. http://dx.doi.org/10.1016/0304-3770(88)90052-6

Schindler, D. W. 2006. Recent advances in the understanding and management of eutrophication. Limnology and Oceanography 51, 1: 356–363. http://dx.doi.org/10.4319/lo.2006.51.1_part_2.0356

Schramm, H. L. and Jirka, K. J. 1989. Effects of aquatic macrophytes on benthic macroinvertebrates in two Florida lakes. Journal of Freshwater Ecology 5: 1–12. http://dx.doi.org/10.1080/02705060.1989.9665208

Sheppard, A. W., Shaw, R. H., and Sforza, R. 2006. Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption. Weed Research 46, 2: 93–117. http://dx.doi.org/10.1111/j.1365-3180.2006.00497.x

Smirnov, N. N. 2013. Physiology of the Cladocera. Academic Press. London, UK.

Smith, V. H., Joye, S. B. and Howarth, R. W. 2006. Eutrophication of freshwater and marine ecosystems. Limnology and Oceanography 51, 1: 351–355. http://dx.doi.org/10.4319/lo.2006.51.1_part_2.0351

Søndergaard, M., Jensen, P. J. and Jeppesen, E. 2001. Retention and internal loading of phosphorus in shallow, eutrophic lakes. The Scientific World Journal 1: 427–442. http://dx.doi.org/10.1100/tsw.2001.72

Søndergaard, M., Bjerring, R. and Jeppesen, E. 2013. Persistent internal phosphorus loading during summer in shallow eutrophic lakes. Hydrobiologia 710, 1: 95–107. http://dx.doi.org/10.1007/s10750-012-1091-3

Stahl, J. B. 1979. Black water and two peculiar types of stratification in an organically loaded strip-mine lake. Water Research 13, 5: 467–471. http://dx.doi.org/10.1016/0043-1354(79)90040-X

Stalder, L. C. and Marcus, N. H. 1997. Zooplankton responses to hypoxia: behavioral patterns and survival of three species of calanoid copepods. Marine Biology 127, 4: 599–607. http://dx.doi.org/10.1007/s002270050050

Talling, J. F. 2001. Environmental controls on the functioning of shallow tropical lakes. Hydrobiologia 458 1–3: 1–8. http://dx.doi.org/10.1023/A:1013121522321

Talling, J. F. 2009. Electrical conductance – a versatile guide in freshwater science. Freshwater Reviews 2, 1: 65–78. http://dx.doi.org/10.1608/FRJ-2.1.4

Talling, J. F. and Talling, I. B. 1965. The chemical composition of African lake waters. Internationale Revue der gesamten Hydrobiologie und Hydrographie 50, 3: 421–463. http://dx.doi.org/10.1002/iroh.19650500307

Thouvenot, L., Haury, J., and Thiebaut, G. 2013. A success story: water primroses, aquatic plant pests. Aquatic Conservation: Marine and Freshwater Ecosystems 23, 5: 790–803. http://dx.doi.org/10.1002/aqc.2387

Toft, J. D., Simenstad, C. A., Cordell, J. R. and Grimaldo, L. F. 2003. The effects of introduced water hyacinth on habitat structure, invertebrate assemblages, and fish diets. Estuaries 26, 3: 746–758. http://dx.doi.org/10.1007/BF02711985

Turner, R. K., Van Den Bergh, J. C., Söderqvist, T., Barendregt, A., van der Straaten, J. et al. 2000. Ecological-economic analysis of wetlands: scientific integration for management and policy. Ecological Economics 35, 1: 7–23. http://dx.doi.org/10.1016/S0921-8009(00)00164-6

Van der Valk, A. G. 2012. The biology of freshwater wetlands. Oxford University Press, New York.

Vareschi, E. 1982. The ecology of Lake Nakuru (Kenya). III Abiotic factors and primary production. Oecologia 55, 1: 81–101. http://dx.doi.org/10.1007/BF00386722

Verberk, W. C. E. P., Siepel, H. and Esselink, H. 2008a. Life-history strategies in freshwater macroinvertebrates. Freshwater Biology 53, 9: 1722–1738. http://dx.doi.org/10.1111/j.1365-2427.2008.02035.x

Verberk, W. C., Siepel, H. and Esselink, H. 2008b. Applying life-history strategies for freshwater macroinvertebrates to lentic waters. Freshwater Biology 53, 9: 1739–1753. http://dx.doi.org/10.1111/j.1365-2427.2008.02036.x

Verheyen, E., Blust, R. and Doumen, C. 1985. The oxygen uptake of Sarotherodon niloticus L. and the oxygen binding properties of its blood and hemolysate (Pisces: Cichlidae). Comparative Biochemistry and Physiology Part A: Physiology 81, 2: 423–426. http://dx.doi.org/10.1016/0300-9629(85)90158-6

Villamagna, A. M., and Murphy, B. R. 2010. Ecological and socio-economic impacts of invasive water hyacinth (Eichhornia crassipes): a review. Freshwater Biology 55, 2: 282–298. http://dx.doi.org/10.1111/j.1365-2427.2009.02294.x

Villamagna, A. M., Murphy, B. R., and Karpanty, S. M. 2012. Community-level waterbird responses to water hyacinth (Eichhornia crassipes). Invasive Plant Science and Management 5, 3: 353–362. http://dx.doi.org/10.1614/IPSM-D-11-00085.1

Waeber, P. O. and Hemelrijk, C. K. 2003. Female dominance and social structure in Alaotran gentle lemurs. Behaviour 140, 10: 1235–1246. http://dx.doi.org/10.1163/156853903771980576

Wallace, A. P. C., Milner-Gulland, E. J., Jones, J. P. G., Bunnefeld, N., Young, R. E. 2015. Quantifying the short-term costs of conservation interventions for fishers at Lake Alaotra, Madagascar. PLoS ONE 10, 6: 1–15. http://dx.doi.org/10.1371/journal.pone.0129440

WHO 2011. Guidelines for drinking-water quality – 4th ed. World Health Organization Press, Geneva, Switzerland. Available at http://www.who.int/water_-sanitationhealth/publications/2011/dwq_guidelines/en

Wilmé, L. 1994. Status, distribution and conservation of two Madagascar bird species endemic to Lake Alaotra: Delacour's grebe Tachybaptus rufolavatus and Madagascar pochard Aythya innotata. Biological Conservation 69, 1: 15–21. http://dx.doi.org/10.1016/0006-3207(94)90324-7

Yu, K. L. and Woo, N. Y. S. 1985. Effects of ambient oxygen tension and temperature on the bimodal respiration of an air-breathing teleost, Channa maculata. Physiological Zoology 58, 2: 181–189. http://www.jstor.org/stable/30158565




Madag. conserv. dev.
ISSN: 1662-2510