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11 resultados encontrados para: TEMA: Isótopos del nitrógeno
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1.
Tesis - Licenciatura
*En proceso técnico. Solicítelo con la bibliotecaria de SIBE-Villahermosa
Dinámica trófica de la laguna El Guanal mediante el uso de isótopos estables de carbono (δ13C) y nitrógeno (δ15N) en el sureste del Golfo de México / José Rodríguez de la Cruz
Rodríguez de la Cruz, José ; García Pech, Javier (director) ; Villa Peralta, Ana del Pilar (asesora) ;
Frontera, Centla, Tabasco : Instituto Tecnológico Superior de Centla , 2018
Clasificación: T/577.16097263 / R6
Bibliotecas: Villahermosa
Cerrar
SIBE Villahermosa
ECO050006412 (Disponible)
Disponibles para prestamo: 1
Nota: En proceso técnico. Solicítelo con la bibliotecaria de SIBE-Villahermosa
Resumen en español

Se realizó la caracterización de la estructura trófica de la Laguna El Guanal (LG) y el Canal Principal (CP) mediante el análisis de isótopos estables de carbono (δ13C) y nitrógeno (δ15N). En el CP se determinó que la principal fuente de carbono proviene del fitoplancton, mientras que en LG el Phragmites australis fue la principal fuente productora de energía mostrando valores enriquecidos de δ13C -13.78. Los valores de δ15N indicaron la posición trófica que ocupa cada especie colectada en el sistema, lo que dio como resultado una mayor diversidad en la red trófica de LG, en este sitio se encontró mayor abundancia de peces dulceacuícolas, en su mayoría la familia de los Cichlidae. Se determinó que en el segundo Nivel Trófico (NT) está constituido por consumidores primarios principalmente especies filtradoras (moluscos) mientras que en el NT intermedio se encontró la mayor abundancia de especies y solo una especie de crustáceo (Macrobrachium acanthurus) en el NT superior se encontraron dos especies, P. splendida y Hyporhamphus mexicanus ocupando esta última especie el NT tope (3.6). El CP presento una similitud en el NT, encontrando de igual forma en el segundo NT a los organismos filtradores (L. tampicoensis y P. alata), y en el NT intermedio las especies C. carpio, A. aeneus, D. petenense, A. alvarezi. Mientras que en los NT superiores se encontraron dos especies marinas (Centropomus undecimalis y Strongylura notata) con NT (3.2 y 3.4 respectivamente).

Índice

DEDICATORIA
AGRADECIMIENTOS
1.1 INTRODUCCIÓN
1.2. OBJETIVOS
1.2.1. Objetivo general
1.2.2. Objetivos específicos
1.3. Hipótesis
2. ANTECEDENTES
2.2. Marco contextual
2.2.2. Detritus
2.2.3. Dinámica Trófica
2.2.4. Diádromos
2.2.4.1. Anádromos
2.2.4.2. Anfídromos
2.2.4.3. Catádromo
2.2.5. Enriquecimiento isotópico
2.2.6. Espectrometría de masas
2.2.7. Hidrófitas
2.2.7.1. Hidrófitas enraizadas de hojas postradas
2.2.7.2. Hidrófitas enraizadas emergentes
2.2.7.3. Hidrófitas enraizadas sumergidas
2.2.7.4. Hidrófitas libremente flotadoras
2.2.8. Humedales
2.2.8.1. Humedal costero
2.2.8.2. Humedal estuarino
2.2.8.3. Humedal lacustre
2.2.8.4. Humedal palustre
2.2.8.5. Humedal ribereño
2.2.9. Isótopo
2.2.9.1. Isótopos de carbono (δ13C)

2.2.9.2. Isótopos de nitrógeno (δ15N)
2.2.9.3. Isótopos estables
2.2.10. Nivel trófico
2.2.11. Plantas C3
2.2.12. Plantas C4
2.2.13. Plantas CAM
2.2.14. Red trófica
2.2.15. Expresión δ13C
2.2.16. Expresión δ15N
3. METODOLOGÍA
3.1. Área de estudio
3.2. Colecta de muestras
3.3. Trabajo de laboratorio
3.3 Análisis de isótopos estables
3.4. Análisis de datos
4. RESULTADOS
4.1 Composición de isótopos estables en la estructura trófica de la red
4.2. Niveles tróficos de los grupos taxonómicos
5. DISCUSIÓN
6. CONCLUSIÓNES
6.1. RECOMENDACIONES
7. BIBLIOGRAFÍA


2.
Tesis - Maestría
Estimación de la posición trófica y conectividad funcional mediada por pargos (Teleostei:Lutjanidae) en un sistema bahía-arrecife del Caribe / León Felipe Martínez Juárez
Martínez Juárez, León Felipe ; Schmitter Soto, Juan Jacobo (Director) ; Mercado Silva, Norman (asesor) ; Carrillo Bibriezca, Laura Elena (asesora) ;
Chetumal, Quintana Roo, México : El Colegio de la Frontera Sur , 2018
Clasificación: TE/597.72097267 / M3
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030008722 (Disponible)
Disponibles para prestamo: 1
Resumen en español

El objetivo de esta investigación fue encontrar diferencias en la dieta, posición trófica y movimientos potenciales de las especies de pargos presentes en tres ambientes del Caribe: canal Río Huach, Bahía de Chetumal-Corozal y laguna arrecifal adyacente. Empleamos isótopos estables de nitrógeno y carbono (δ15N, δ13C) en conjunto con la revisión del contenido estomacal y de la madurez gonadal. Se realizaron modelos isotópicos de mezcla para estimar la composición y origen de sus alimentos, así como evidencias de desplazamientos. Los pargos tuvieron una dieta compuesta casi en su totalidad por peces y crustáceos. Se observó una compensación en la contribución relativa por peso entre dichas presas. En los modelos de mezcla se reflejó como un aumento en el consumo de presas con un nivel trófico alto (consumidores secundarios) a costa de presas de nivel trófico bajo (consumidores primarios). Los resultados de isótopos mostraron que su dieta depende en mayor medida de los recursos de la zona en la que viven y en menor medida de la especie de pargo. Por lo anterior, los pargos se pueden considerar como mesodepredadores piscívoro-invertívoros. Lutjanus griseus y L. jocu fueron las especies más piscívoras y con posición trófica mayor, mientras que Ocyurus chrysurus tuvo una mayor dependencia en crustáceos y menor posición trófica. Sólo se encontraron evidencias de movimientos reproductivos en L. griseus, los ejemplares con gónadas próximas a desovar o desovadas tuvieron una composición isotópica distinta a la del resto de pargos del ambiente en el que fueron capturados. Observamos individuos muy pequeños de L. synagris sexualmente maduros dentro de la bahía, en lo que podrían ser agregaciones pre-reproductivas. En conjunto, las aproximaciones isotópicas y tradicionales resaltaron las diferencias en el uso de hábitat y recursos, incluyendo la conectividad funcional dada por el forrajeo y la reproducción de las especies de pargo

Índice

Resumen
Palabras clave:
Capítulo introductorio
Capítulo central: manuscrito enviado a Marine Ecology Progress Series
Trophic position and functional connectivity of snappers (Teleostei: Lutjanidae) in a bay-to-reef Caribbean system
Abstract
Key Words
INTRODUCTION
Ecological niche studies and their approaches
Stable isotopes and mixing models approach
Coastal ecosystems, ecohydrological connectivity and nursery areas
Regional context and fish
Objectives
MATERIAL AND METHODS
Study area
Study design and sampling
Sample processing for Stable Isotope Analysis (SIA)
Index of Relative Importance, Vacuity Index
Stable Isotope Analysis (SIA)
Trophic position and trophic fractionation
Gonadosomatic Index
Statistical
RESULTS
Stomach contents
Prey predominance in diet
Stable Isotope Mixing Models (SIMM)
Trophic position
Isotopic and non-isotopic evidence of recent reproductive migration
Statistical comparisons
DISCUSSION
Stomach content and relative importance
SIMM
Trophic position
Functional connectivity
Reproductive migrations
Habitat use and ecological traits
Management implications
CONCLUSIONS
Author contributions
Acknowledgments
Literature cited
Appendix A
Appendix B
Appendix C
Electronic supplement S3
Capítulo final Literatura adicional citada en los capítulos introductorio y final
Apéndice 1
Apéndice 2
Apéndice 3


3.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Evidence of intense suboxia and anoxia in a tropical bay of the Gulf of California
Sánchez, Alberto (autor) ; Rodríguez Figueroa, Griselda Margarita (autora) ; Shumilin, Evgueni N. (coaut.) ; Ortíz Hernández, Ma. Concepción (autora) ;
Contenido en: Continental Shelf Research Vol. 168 (September 2018), p. 21-27 ISSN: 0278-4343
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

The expansion of the upper boundary of the oxygen minimum zone (OMZ) has been associated with the low solubility of oxygen in the surface ocean due to global warming in tropical regions. However, sedimentary records of δ15N of sinking particulate organic matter and sediments suggest that oxygen solubility is controlled by oceanographic forcing in the tropical equatorial region. To determine the intensification of the OMZ within its upper border, δ15N analysis of the organic matter in superficial sediments of La Paz Bay was carried out. In the present work, 115 samples of superficial sediment were collected in the interval of 2–407 m depth in La Paz Bay. The surface sediments were analysed for the nitrogen isotopic composition of their organic matter. Hypoxia conditions (< 60 μM) at 100 m to depth suggest an intense denitrification of the water column that it was reflected in the sedimentary δ15N. The δ15N of the organic matter is 1.5‰ greater in the bay than in the mouth of the Gulf of California, indicating greater denitrification towards the interior of the bay with respect to the gulf mouth. The intense suboxia/anoxia conditions have been maintained due to a well-mixed water column that promotes exported productivity in La Paz Bay.


4.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Variation in isotopic trophic structure and fish diversity in mangrove systems subject to different levels of habitat modification in the Gulf of California, Mexico
López Rasgado, Francisco Javier ; Lluch Cota, Salvador E. (coaut.) ; Balart, Eduardo F. (coaut.) ; Herzka, Sharon Z. (coaut.) ;
Contenido en: Bulletin of Marine Science Vol. 92, no. 4 (October 2016), p. 399-422 ISSN: 0007-4977
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Anthropogenic modification of mangrove systems can lead to decreased habitat quality, potentially affecting food web structure and ecosystem function. Based on carbon and nitrogen stable isotopes, we evaluated the trophic structure of the fish communities from three mangrove systems in southern Baja California, Mexico, subject to varying levels of habitat modification. We hypothesized that anthropogenic habitat modification leads to differences in niche space (and hence trophic structure). We applied a Bayesian approach to the calculation of community level isotope-based metrics of functional trophic structure and compared the results to a structural (Shannon-Wiener) index of diversity. Frequency distributions of stable isotope ratios revealed differences between the highly modified mangrove system and those with limited or no habitat modification. Comparison of the isotopic composition of the dominant fish species sampled in summer and winter indicated limited seasonal differences in this arid region. However, isotope-derived metrics of niche space were evaluated in the most highly modified mangrove system, suggesting a greater complexity in nutrient and primary production sources, a higher level of dietary specialization, and low functional redundancy. Fishes from the most pristine mangrove system exhibited highest diversity, a more limited range of isotopic values, and smaller measures of isotopic niche space, indicative of higher trophic redundancy. Comparison of the standardized (baseline-controlled) species-specific isotope ratios indicated that in 37% of cases isotopic differences persisted, further supporting our interpretation of variations in trophic structure. This research highlights that mangrove habitat modification has a marked influence on functional trophic diversity, as well as the fish community structure.


5.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Differences in food web structure of mangroves and freshwater marshes: evidence from stable isotope studies in the Southern Gulf of Mexico
Sepúlveda Lozada, Alejandra ; Mendoza Carranza, Manuel (coaut.) ; Wolff, Matthias (coaut.) ; Saint Paul, Ulrich (coaut.) ; Ponce Mendoza, Alejandro (coaut.) ;
Contenido en: Wetlands Ecology and Management Vol. 23, no. 2 (April 2015), p. 293-314 ISSN: 1572-9834
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Tropical coastal habitats like marshes, mangroves, and submerged grasses comprise diverse plant and animal communities and a certain degree of connectivity with other ecosystems. We compared the food web structure of a fringing mangrove-seagrass habitat and three fluvio-lagoons with marsh-eelgrass and mangrove-bare sediments during a dry season in Terminos Lagoon and Centla Wetlands, Southern Gulf of Mexico. Analysis of d13C and d15N stable isotopes in tissues of aquatic consumers, primary producers, and other carbon sources, in combination with isotope- based Bayesian methods, were performed to determine the main food sources and the isotopic niche of the consumers’ communities. Consumers in the man- grove-seagrass site showed high dependence on phytoplankton (average contribution 31 %), macroal- gae (20 %) and organic matter derived from seagrass- es (17 %). In the fluvio-lagoons, consumers showed high dependence on marginal vegetation (16–46 %). Phytoplankton and mangrove epiphytes comprised other important resources at these sites (with contri- butions of 24–44 %). The isotopic niche of consumers from the fringing mangrove-seagrass site did not overlap with those from the fluvio-lagoons. Moreover, despite the predominance of generalist consumers in all sites, differences in their isotopic niche area were observed, with consumers from the marsh-eelgrass site showing the narrowest. This suggests that con- sumer resource availability greatly differs in these habitats. Our results provide valuable information that help increase our understanding about the trophic structure in these important estuarine systems.


6.
- Artículo con arbitraje
Conservative nutrient use by big-leaf mahogany (Swietenia macrophylla king) planted under contrasting environmental conditions
Medina, Ernesto ; Cuevas Viera, Elvira (coaut.) (1950-) ; Lugo, Ariel E. (coaut.) ; Terezo, Evaristo (coaut.) ; Jiménez Osornio, Juan José María (coaut.) ; Macario Mendoza, Pedro A. (coaut.) ; Montañez Escalante, Patricia Irene (coaut.) ;
Contenido en: Revista Árvore Vol. 38, no. 3 (May/June 2014), p. 479-488 ISSN: 0100-6762
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
ECO030001038 (Disponible)
Disponibles para prestamo: 1
PDF
Resumen en: Inglés | Frances |
Resumen en inglés

We analyzed the nutritional composition and isotope ratios (C and N) of big-leaf mahogany (Swietenia macrophylla King) leaves in plantations established on contrasting soils and climates in Central America (State of Quintana Roo, Yucatán, México) and South America (State of Pará, Brazil). The objective was to determine the adaptability of this species to large differences in nutrient availability and rainfall regimes. Nutrient concentrations of leaves and soils were determined spectrophotometrically, and isotope ratios were measured using mass spectrometric techniques.In Pará soils were sandier, and acidic, receiving above 2000 mm of rain, whereas in Quintana Roo soils were predominantly clayey, with neutral to alkaline pH due to the underlying calcareous substrate, with about 1300 mm of rain. Leaf area/weight ratio was similar for both sites, but leaves from Quintana Roo were significantly smaller. Average N and K concentrations of adult leaves were similar, whereas Ca concentration was only slightly lower in Pará in spite of large differences in Ca availability. Leaves from this site had slightly higher P and lower Al concentrations. Differences in water use efficiency as measured by the natural abundance of 13C were negligible, the main effect of lower rainfall in Quintana Roo seemed to be a reduction in leaf area. The N isotope signature (δ15N) was more positive in Pará than in Quintana Roo, suggesting higher denitrification rates in the former. Results reveal a calciotrophic behavior and a remarkable capacity of mahogany to compensate for large differences in soil texture and nutrient availability.

Resumen en frances

Analisou-se a composição nutricional e isotópica (C e N) de folhas de mogno (. Swietenia macrophylla King) em plantações estabelecidas em solos e climas contrastantes na América Central (Quintana Roo, Yucatán, México) e na América do Sul (Pará, Brasil). O objetivo foi determinar a adaptabilidade dessa espécie para grandes diferenças na disponibilidade de nutrientes e regimes de chuva. As concentrações de nutrientes das folhas e solos foram determinadas espectrofotometricamente, e razões isotópicas foram medidas utilizando espectrometria de massa. No Pará, os solos foram mais arenosos e ácidos, recebendo acima de 2.000 mm de chuva, enquanto em Quintana Roo os solos foram predominantemente argilosos, com pH neutro a alcalino, devido ao substrato calcário subjacente, com cerca de 1.300 mm de chuva. A razão área/peso foliar foi semelhante para ambos os sítios de estudo, mas em Quintana Roo as folhas foram significativamente menores. Concentrações de N e K em folhas adultas foram semelhantes. A concentração de Ca foi apenas ligeiramente inferior no Pará, apesar das grandes diferenças na disponibilidade de Ca. Folhas desse sítio possuíam concentrações ligeiramente maiores de P e menores de Al. Diferenças na eficiência do uso da água medida pela δ13C foram insignificantes, e o principal efeito da menor precipitação em Quintana Roo parece ser uma redução na área foliar. Assinatura isotópica do N (δ 15N) foi mais positiva no Pará, que em Quintana Roo, sugerindo maiores taxas de desnitrificação no primeiro sítio de estudo. Os resultados revelaram comportamento calciotrófico e uma notável capacidade do mogno para compensar as grandes diferenças de textura e disponibilidade de nutrientes do solo.


7.
Capítulo de libro - Memoria en extenso
*Solicítelo con su bibliotecario/a
Impacto antropogénico en ambientes marinos tropicales: uso de isótopos estables de nitrógeno
Sánchez Martínez, Alberto de Jesús ; Márquez, Mariana (coaut.) ; Talavera Sáenz, Ana Luisa (coaut.) ; Ortíz Hernández, Ma. Concepción (coaut.) ;
Contenido en: Memorias/proceedings. X simposio latinoamericano de química analítica ambiental y sanitaria Puebla, Puebla, México : Universidad Autónoma de Tabasco : Universidad Michoacana de San Nicolás de Hidalgo : Universidad de Guanajuato, Academia de Ingeniería, c2013 p. 127-132
Nota: Solicítelo con su bibliotecario/a
Resumen en español

La contribución de nitrógeno enriquecido en 15N está directamente relacionada con el incremento de la descarga de agua residual (DAR) en áreas con mayor desarrollo turístico (Cancún, >3 millones de turistas por año de 2007 a 2011 y 0.7 millones de población residente) y decrece hacia Mahahual (~0.4 millones de turistas por año en 2007 a 2011 and 0.25 millones de población residente). El ß15N de Thalassia testudinum proveniente de sitios con diferentes niveles de desarrollo turístico y población, es comparado para detectar aportes de N de DAR. El ß15N de T. testudinum fue significativamente más bajo en Mahahual que en Cancún. Por lo tanto se sugiere que Mahahual pueden ser usados como línea base del seguimiento isotópico sobre la presión ambiental del ecosistema marino. El aporte de N antropogénico tiene el potencial en impactar, tanto ambiental como económicamente las praderas de pastos marinos y los arrecifes de coral a lo largo de la costa de Quintana Roo y el Caribe.

Resumen en inglés

The contributions of nitrogen enriched in 15N are directly related to the increase of wastewater discharge (WD) inputs in areas with high tourism development (Cancun, >3 million tourists per year from 2007 to 2011 and 0.7 million of resident population) and decreased towards Mahahual (about 0.4 million tourists per year in 2007 to 2011 and 0.25 million of resident population). We compared the ß15N from Thalassia testudinum collected at sites with different levels of tourism development and population to detect the N inputs of WD. The ß15N from T. testudinum was significantly lower at Mahahual than Cancun. Therefore is suggested that Mahahual may be used as a baseline isotopic monitoring over environmental pressure on the marine ecosystem. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.


8.
- Artículo con arbitraje
Stable nitrogen isotopes in the turtle grass Thalassia testudinum from the Mexican Caribbean: implications of anthropogenic development
Sánchez Martínez, Alberto de Jesús ; Ortíz Hernández, Ma. Concepción (coaut.) ; Talavera Sáenz, Ana Luisa (coaut.) ; Aguíñiga García, Sergio (coaut.) ;
Contenido en: Estuarine, Coastal and Shelf Science Available Vol. 135 (December 2013), p. 86–93 ISSN: 0272-7714
PDF
Resumen en: Inglés |
Resumen en inglés

Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of tourism development (Nichupte Lagoon in Cancun) and decreased toward Bahia Akumal and Tulum. The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos. In areas of the lowest development and with tourist activity restricted, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were relatively enriched compared to Mahahual and Puerto Morelos. Therefore, Puerto Morelos and Mahahual may be used for baseline isotopic monitoring where tourist activities are growing and can lead to environmental pressure on the reef lagoon ecosystem. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.


9.
- Artículo con arbitraje
Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico
Mendoza Carranza, Manuel ; Hoeinghaus, David J. (coaut.) ; Garcia, Alexandre M. (coaut.) ; Romero Rodríguez, Ángel (coaut.) ;
Contenido en: Neotropical Ichthyology Vol. 8, no. 1 (2010), p. 171-178 ISSN: 1982-0224
PDF
Resumen en: Inglés | Portugués |
Resumen en inglés

Mangrove and seagrass habitats are important components of tropical coastal zones worldwide, and are conspicuous habitats of Centla Wetland Biosphere Reserve (CWBR) in Tabasco, Mexico. In this study, we examine food webs in mangrove- and seagrass-dominated habitats of CWBR using stable isotope ratios of carbon and nitrogen. Our objective was to identify the importance of carbon derived from mangroves and seagrasses to secondary production of aquatic consumers in this poorly studied conservation area. Carbon and nitrogen isotope ratios of basal sources and aquatic consumers indicated that the species-rich food webs of both habitats are dependent on riparian production sources. The abundant Red mangrove Rhizophora mangle appears to be a primary source of carbon for the mangrove creek food web. Even though dense seagrass beds were ubiquitous, most consumers in the lagoon food web appeared to rely on carbon derived from riparian vegetation (e.g. Phragmites australis). The introduced Amazon sailfin catfish Pterygoplichthys pardalis had isotope signatures overlapping with native species (including high-value fisheries species), suggesting potential competition for resources. Future research should examine the role played by terrestrial insects in linking riparian and aquatic food webs, and impacts of the expanding P. pardalis population on ecosystem function and fisheries in CWBR. Our findings can be used as a baseline to reinforce the conservation and management of this important reserve in the face of diverse external and internal human impacts.

Resumen en portugués

Manguezais e pradarias de gramíneas são importantes componentes das zonas costeiras tropicais em todo o mundo, sendo habitats comuns nos “Pântanos de Centla”, uma Reserva da Biosfera localizada em Tabasco, México. Nesse trabalho, são investigadas as teias alimentares de habitats dominados por manguezais e pradarias de gramíneas, através de isótopos estáveis de carbono e nitrogênio, tendo como objetivo identificar a importância do carbono derivado desses produtores para a produção aquática secundária nessa unidade de conservação tão pouco estudada. As razões isotópicas de carbono e nitrogênio das fontes basais e dos consumidores aquáticos indicam que as teias alimentares, ricas em espécies, de ambos os habitats, são dependentes da produção ripária. O abundante mangue-vermelho Rhizophora mangle parece ser a fonte primária de carbono no habitat dominado por manguezais. Em contraste, muito embora as pradarias de gramíneas sejam conspícuas no ambiente lagunar estudado, muitos dos consumidores da teia alimentar nessa região parecem depender do carbono oriundo da vegetação ripária (e.g. Phragmites australis). A espécie de bagre exótica Pterygoplichthys pardalis possui assinaturas isotópicas que se sobrepõem a das espécies nativas (incluindo algumas de elevado valor comercial na pesca), sugerindo competição potencial por recursos. Novas investigações deveriam avaliar o papel dos insetos terrestres como elo de conexão entre as teias alimentares da mata ripária e do ambiente aquático, bem como os impactos da expansão da população de P. pardalis sobre o funcionamento do ecossistema e das pescarias no “Pântano de Centla”. Considerando os múltiplos impactos antrópicos na região, os resultados obtidos no presente trabalho podem ser utilizados como uma base de referência em programas de gerenciamento e conservação da diversidade nessa importante Reserva da Biosfera.


10.
Artículo
Stable isotopes in jumbo squid (Dosidicus gigas) beaks to estimate its trophic position: comparison between stomach contents and stable isotopes
Ruiz-Cooley, R. Iliana ; Markaida Aburto, Unai (coaut.) ; Gendron, D. (coaut.) ; Aguíñiga, Sergio (coaut.) ;
Contenido en: Journal of the Marine Biological Vol. 86. no. 2 (2006), p. 437-445 ISSN: 0025-3154
Resumen en: Inglés |
Resumen en inglés

Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quanti¢ed C and Nisotope ratios in muscle, and stomach content analysis revealed that larger-sized maturing squid showed a higher trophic position than medium-sized individuals. However, a discrepancy between stomach contents versus stable isotope analyses was found in evaluating trophic relationships. Simple dilution models as a function of growth were used to estimate the C and N renewal dietary shift for jumbo squid. Estimates of the initial C and N pools in D. gigas with an initial age of 70 days and 210 days indicated isotopic shifts of 32% after a threefold biomass increase and 25% after a fourfold biomass increase, respectively. Additionally, beak samples of jumbo squid were evaluated as an alternative tissue to estimate squid trophic position using stable isotopes. The results showed a signi¢cant correlation between stable isotope ratios from muscle and beak samples. Muscle isotope values were higher than beak by 1%and 4% for d13C and d15N respectively. A test with jumbo squid beaks collected from a stomach of a stranded sperm whale con¢rmed the viability of this method.