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Mangrove Habitat (mangrove + habitat)
Selected AbstractsHabitat use, abundance, and persistence of Neotropical migrant birds in a habitat matrix in northeast BelizeJOURNAL OF FIELD ORNITHOLOGY, Issue 3 2010Camila Gómez-Montes ABSTRACT To ensure adequate protection of nonbreeding habitats used by Neotropical migratory landbirds, we must first address questions about habitat use and quality. On the Yucatan peninsula, migrants use many habitats, several of which remain unstudied, and methodological differences preclude interhabitat comparisons based on studies to date. We used distance sampling along line transects in six habitats in northeast Belize to examine use of previously unstudied habitats (e.g., salt marsh) by Neotropical migrants and to permit comparison across habitats. We calculated unadjusted and adjusted (for detectability) density estimates for individual migrant species and for all species combined to generate hypotheses about habitat quality based on the assumption that density and quality are positively correlated. Adjusted density estimates for all migrants were highest in black mangrove habitat (1799 ± 110 ind/km2), intermediate in three forest types and milpa (range 598,802 ind/km2), and lowest in salt marsh (207 ± 32.3 ind/km2). By combining density estimates with habitat availability in our study region, we estimated that evergreen forest and black mangrove supported 70% and 9% of the region's migrant population, respectively. At the species level, five of the 10 most common species had habitat preferences (>50% detections in one habitat). Given the diversity of habitat preferences among species and apparent seasonal movements, our results indicate that Neotropical migrants in northeast Belize are dependent on a matrix of interconnected habitats. RESUMEN Para asegurar la protección adecuada del hábitat no- reproductivo utilizado por aves migratorias Neotropicales terrestres, debemos responder preguntas sobre el uso y la calidad del hábitat. En la península de Yucatán, lasaves migratorias utilizan muchos hábitats, varios de los cuales aún continúan sin ser estudiados. Además las diferencias metodológicas evitan hacer comparaciones inter-hábitat basadas en los estudios que se han hecho hasta ahora. Utilizamos unmuestreo a lo largo de transectos de distancia variable, en seis hábitats, algunos previamente no estudiados (ej. ciénagas salobres), en el noreste de Belize para examinar y comparar el uso por parte de las migratorias Neotropicales, Calculamos estimados de densidad, ajustados y no ajustados (para detectabilidad), para especies particulares de migratorias y para todas las especies combinadas para generar una hipótesis sobre la calidad del hábitat basándonos en la presunción que la densidad estaría positivamente correlacionada con la calidad del hábitat. Los estimados de densidad ajustados para todos los migratorios fueron más altos en mangle negro (1799 ± 100 ind/km2), intermedios en tres tipos de bosque y milpa rango 598,802 ind/km2) y menores en ciénagas salobres (207 ± 32.3 ind/km2). Combinando los estimados de densidad con la disponibilidad de hábitats en nuestra región de estudio, estimamos que el bosque siempreverde y el mangle negro sostienen el 70% y 9% de los migratorios en la región, respectivamente. A nivel de especies, cinco de las 10 especies más comunes tienen preferencias de hábitat (>50% de las detecciones en un hábitat). Dada la diversidad de preferencias de hábitat entre especies y el aparente movimiento estacional, nuestros resultados indican que las aves migratorias Neotropicales en el noreste de Belize dependen de una matriz de hábitats interconectados. [source] Diversity, conservation status and threats to native oysters (Ostreidae) around the Atlantic and Caribbean coasts of South AmericaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2009Alvar Carranza Abstract 1.Despite the extensive literature on the ecology, systematics and culture of oysters worldwide, an assessment of their diversity, distribution and conservation status for the Atlantic and Caribbean coasts (i.e. depth <50 m) of South America is lacking. Such information is crucial because of the increasing coastal development that threatens most nearshore habitats throughout the region. 2.The available information on oysters on Atlantic and Caribbean coasts is reviewed with a focus on identifying regional conservation priorities based on ecological and socio-economic importance, as well as the magnitude of current or potential threats faced by oyster populations. The current status of ,- taxonomy within the Ostreidae was also examined. 3.Ten species of native Ostreidae (plus three introduced species) inhabit the coastal waters of the Atlantic and Caribbean coasts of South America. 4.Oyster species were ranked according to their biological/ecological and socio-economic value and conservation status within 10 distinct ecoregions. Crassostrea gasar in the Eastern Brazil ecoregion, C. rhizophorae in the Central Caribbean ecoregion and Ostrea puelchana in the North Patagonian Gulfs ecoregion should receive the highest priority for immediate conservation action due to extensive loss of mangrove habitat in the two former regions and evidence of decline of one of the most important populations for the latter. The need for a standardized methodology to assess the status of oyster populations throughout the ecoregions is identified. 5.On a local scale, the allocation of territorial use rights for fisheries under a collaborative/voluntary community framework is strongly advocated to fulfil management, conservation and poverty alleviation goals in these developing countries. Copyright © 2008 John Wiley & Sons, Ltd. [source] Mud crab pen culture: replacement of fish feed requirement and impacts on mangrove community structureAQUACULTURE RESEARCH, Issue 8 2010Jurgenne H Primavera Abstract Brackishwater pond culture has been a major factor in mangrove loss in Southeast Asia, hence, the need to develop environment-friendly technologies such as mud crab Scylla (Portunidae) culture in mangrove pens exists. This study evaluated the effects of mud crab netpen systems in central Philippines on mangrove macroflora, and the replacement of dietary fish with low-cost pellets. Wild or hatchery-sourced Scylla olivacea and Scylla serrata were stocked at 0.5,0.8 m,2 in 167,200 m2 nylon netpens (2.3 cm stretched mesh) in Avicennia -dominated mangrove habitats. The feeding treatments were: (A) Zarraga: (1) no feeding (natural productivity), (2) no feeding for 1 month+supplementary feeding, (3) fish biomass and (4) low-cost pellets, and (B) Batan: (1) fish biomass and (2) pellets+fish biomass. Feeds were given ad libitum twice daily. Growth and survival rates of S. olivacea in Zarraga pens were not significantly different among treatments, although crabs fed fish biomass had the highest survival, body weight and production. Similarly, growth and survival of S. serrata were not significantly different between the Batan treatments. Economic analysis of the latter gave a 38.5% return on investment (ROI) and 2.6 years payback period (PP) for pellets+fish biomass treatment compared with 27.5% ROI and 3.6 years PP for fish alone. Sensitivity analysis showed an improved economic performance of the pellets+fish biomass treatment by increasing the survival rate. Evaluation of mangrove community structure showed that crab culture reduced species diversity, numbers and biomass of seedlings and saplings, but not of mangrove trees. Therefore, mud crab pen culture is recommended for mangrove sites with mature trees, but not seedlings and saplings, and low-cost pellets can reduce dependence on fish biomass. [source] RNA/DNA ratio of crabs as an indicator of mangrove habitat qualityAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009Valter Amaral Abstract 1.Pollution of mangrove ecosystems puts their future and that of local communities at risk. Only the use of informed and integrative approaches will successfully maintain and restore these valuable ecosystems. 2.Biochemical indicators of organism physiological condition have been widely used to evaluate habitat quality and for early detection of the impact of stressors. Mangrove crabs may be useful bioindicators of the quality of mangrove habitats, as they are characteristic and ecologically important organisms in mangrove environments. 3.The physiological condition (evaluated by the RNA/DNA ratio) of Perisesarma guttatum (Grapsidae) and Uca annulipes (Ocypodidae) was assessed to determine its potential as an indicator of habitat quality in one polluted and two relatively unpolluted Mozambican mangroves, during the rainy and dry seasons. 4.Both species showed seasonal effects on RNA/DNA ratio, but only U. annulipes was significantly affected by pollution. RNA/DNA ratio of U. annulipes may thus be a useful indicator of pollution and seasonality in mangrove habitats. There was a synergistic negative effect of the rainy season and pollution on the RNA/DNA ratio of U. annulipes. Due to higher DNA, rather than lower RNA contents, the RNA/DNA ratio of P. guttatum was always significantly lower than that of U. annulipes. 5.The knowledge gathered in this study can be used in integrative strategies, policies and programmes aiming to sustain, maintain and restore mangrove areas, and for the evaluation of mangrove habitat quality. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||