Estimating the contribution of terrestrial organic matter in the South-Western margin of Baja California during the late Holocene

Galileo Rodríguez Amador Curso 2013/2014 Mª Dolores Gelado Caballero Alberto Sánchez González A Trabajo Fin de Título para la obtención del título Grado en Ciencias del Mar ESTIMATING THE CONTRIBUTION OF TERRESTRIAL ORGANIC MATTER IN THE SOUTH-WESTERN MARGIN OF BAJA CALIFORNIA DURING THE LATE HOLOCENE ESTIMATING THE CONTRIBUTION OF TERRESTRIAL ORGANIC MATTER IN THE SOUTH-WESTERN MARGIN OF BAJA CALIFORNIA DURING THE LATE HOLOCENE Datos personales del estudiante: Galileo Rodríguez Amador (galileo.rodri[email protected]lpgc.es) Estudiante de Grado de Ciencias del Mar Curso 2013/2014 Facultad de Ciencias del Mar, Universidad de Las Palmas de Gran Canaria. Participante en el programa de movilidad EEUU-America Latina, en la Universidad Autónoma de Baja California Sur (UABCS) y el Centro Interdisciplinario de Ciencias marinas, Instituto Politécnico Nacional (CICIMAR-IPN). Datos personales del tutor y cotutor: Mª Dolores Gelado Caballero Universidad de Las Palmas de Gran Canaria Facultad de Ciencias del Mar Departamento de Química Alberto Sánchez González CICIMAR-IPN Departamento de Oceanología Laboratorios de Biogeoquímica Ambiental X Galileo Rodríguez Amador Estudiante X Mª Dolores Gelado Caballero Tutor X Alberto Sánchez González Cotutor 1 Table of Contents Abstrac 3 Introduction 4 Study Case 5 Justification, hypothesis and objectives 6 Material and Methods 7 Results 10 Discussion 13 Conclussion 14 Acknowlegment 15 References 15 2 List of figures Figure 1. Study area showing the margin of Magdalena. 7 Figure 2. OMZ on the Pacific Coast of Mexico. Image taken from the web nodc.noaa.gov. 8 Figure 3. Age model adapted from van Geen et al 2003 and Marchitto et al 2007. 8 Figure 4. Temporal variation of organic carbon (top) and nitrogen (bottom)expressed as % in the marine sediment Magdalena margin during the last 5000 years. 11 Figure 5. C:N ratio (top) and N:C ratio (bottom) and δ13C (‰) values in the samples (black points) and reported range of C:N and N:C ratios and δ13C for marine and terrestrial OM in the boxes are presented. 12 Figure 6. Temporal variations of the contributions of OM of terrestrial origin: a) calculated with the equation of Schultz and Calder values (1976), b) and c) calculated with Perdue and Koprivnjak (2007) equations values. 13 List of tables Table 1. Marine and terrestrial standards of δ13C and N:C and C:N ratios. 10 Table 2. Organic Carbon and Nitrogen sediment composition (%) and δ13C values found in Magdalena margin. 10 Table 3. Reported values of %C, %N and δ13C in zones under influence of an OMZ. 14 3 Abstract The organic matter in the water column and sediment in transitional and marine environments in the ocean is described by a binary mixture of marine and terrestrial sources. The C:N ratio and δ13C of samples and sources is used in a linear equation to estimate the fraction of organic matter (OM) from land in aquatic and sedimentary environments. However, terrestrial OM is relatively depleted in N and this fraction has been seriously and systematically underestimated by this misinterpretation of the C:N ratio and δ13C. Additionally, the composition of the Earth's organic matter is not well known in the region of Magdalena, as is the case in many studies in arid areas with little or no input from rivers. In this work new data for reason N:C and δ13C core are shown severity collected at 700 m depth in order to evaluate the contribution of different sources of OM in the south-western Baja California margin, characterized by extensive oxygen minimum zone and high primary productivity. The N:C ratio suggests that the contribution of various land-based MO of between 19 and 57% during the late Holocene. The binary mixture the N:C ratio and δ13C of OM appears indicate that marine source remains the dominant source. Key Words: Sediment, N:C ratio, δ13C, Organic Matter, OMZ, Holocene 4 Introduction Understanding the dynamics of biogeochemical cycles of organic matter (OM) requires knowledge of both the processes that control the distribution of the same as its source. At the bottom of the ocean margin sediments found that are rich in organic matter, both of marine origin and terrestrial origin (Smith et al., 2008). During the passage of the years, sedimentation buries this matter gradually, forming a register in which every centimeter of sediment may reflect from decades to centuries of information, depending on the area and its rate of sedimentation. In places with a high rate of sedimentation, sedimentary records have higher resolution, where every centimeter shows very few years (van Geen et al., 2003). This lets us know what changes occurred in short time scale. The Holocene is the current geological period, comprising almost the last 12.000 years. Its onset is characterized by climate change that marked the end of the last glaciation (Wanner et al., 2008). This work is focus on the late Holocene which started 3,000 years ago. The oceans are an important part of the carbon flux. Variations of carbon flux on a planetary scale ranging from millions of years for processes related to the earth's crust, to seconds or days for those related to the atmosphere-ocean interface and the photosynthesis (Sanchez and Carriquiry 2007). It is well known that photosynthetic organisms fix atmospheric CO2 to form organic molecules for vital development which are incorporate in their tissues. After the death of organisms, the organic matter is degraded being the sequestered C return as CO2 to the atmosphere. Occasionally in the marine environment, this process does not occur in the same way. The died organisms remains sink and are partially degraded in the water column and sediment. Finally they become part of the sediment, thus being trapped organic matter formed by photosynthetic processes (Zonneveld et al., 2010). It should be note, the organic matter in the sediment is a combination of marine and terrestrial inputs. One of the major sources is the primary production emerged in the water column, which after the death of the organisms and their fall to the bottom, will be part of the sediment. On the other hand, the rivers provide huge amounts of organic matter from the continental basins sweep along their course (Zonneveld et al., 2010). Moreover in arid regions where there is no river source, the contribution of organic matter from land may be dominated by wind pathway (Sánchez et al., 2013). Marine sediments can be used as temporary records that reflect real climate and global change (Ortiz et al., 2004). In the particular case of Magdalena margin, an exceptionally sedimentary high rate allow high resolution of temporary record because every centimeter of 5 sediment responds to a variation between 10 and 30 years of sedimentation (van Geen et al., 2003 ). However it should also be considered another factor, the low oxygen concentration which limits the degradation of organic matter falling into the water column and down in the sediment (Guíñez et al., 2010). That is the reason because the oxygen minimum zones (OMZ) play a crucial role in the preservation of organic matter in marine sediment. In addition, these low oxygen concentrations inhibit the presence of benthic organisms which produce the bioturbation of sediments. In consequence, the formation of distinct bands in the layers of accumulated particles and the preservation these sediments is realized (Soutar and Crill, 1977). To determine the source of the organic matter present in the sediment, the elemental and isotopic composition is analyzed. Knowing the δ13C and N: C ratio, is possible to infer the source of organic carbon and nitrogen since each source has a characteristic isotopic signature (Hu et al., 2006.). Traditionally, C: N ratio has been used to the determination of the sources of organic matter in the sediment. However, the fraction of terrestrial OC is underestimated by the C:N ratio because the terrestrial organic matter is relatively depleted in nitrogen. Some authors have suggested the use of atypical N:C ratio in order to correct this mentioned error (Koprivnjak and Perdue, 2007). Usual values reported for δ13C of organic matter from terrestrial plants varies between - 26 ‰ and -28 ‰ with an average of 27 ‰ and for organic matter of planktonic organisms the values ranging from -20 ‰ to -22 ‰ (Hu et al 2009).In the other hand, the C: N ratio of the organic material of marine origin have values between 5 and 8 in OM with a terrestrial origin they are > 15 . Study case In this work we study the core samples collected with gravity in the margin of Magdalena, a region influenced by OMZ and characterized by a high rate of sedimentation (van Geen et al., 2003). Several studies have addressed the characterization of carbon fluxes and organic matter during the last 50000 (Sanchez and Carriquiry 2007) in this region. Despite that not many have achieved reliably determine the source of organic matter in this area remaining yet to establish whether its origin lies in land-based or marine sources. Moreover some data obtained in this area might not have been properly interpreted as C:N ratio was used to origin proxy which, as already noted above, likely underestimates the 6 contribution of terrestrial organic matter because nitrogen levels are quite low in that OM (Koprivnjak and Perdue, 2007). Justification, hypothesis and objectives Although it is true that the quantitative and qualitative description of accumulation rates Organic Carbon, Organic Nitrogen, Organic Phosphorous, etc. which have been made in previous work in this region to characterize the OM has relevance, more efforts are still needed to establish the origins of OM and for better understanding of the variables that control the fluxes of carbon in this region. Furthermore, the composition of marine sediment and the quantitative differences between the sources of each of the components of the OM should be established to use as a temporal recording of climate changes at regional and global scale and establish future scenarios based on that knowledge. Depending on the origin of organic matter found in sediments and its variation over time relationships with changes in climate and marine production, and fluvial and dust OM input could be ascertained Our hypothesis is based on the fact that the biogeochemical tracers used for characterization of marine sediment in the region of Magdalena so far have been insufficient to establish totally the cycle of organic matter during the Holocene. The study of sedimentary records gravity cores collected in the southwestern margin of the peninsula of Baja California during the last 5000 years should reveal the influence of the contribution of terrestrial material through the combined application of techniques for elemental and isotopic analysis of the N: C ratio. The proposed objectives are: 1. Concluding the sources of organic matter δ13C based on and N: C ratio in the range of Magdalena. 2. Differentiate between sources of organic matter from land and sea in the range of Magdalena. 3. Estimate the contributions of organic matter from land in the range of Magdalena. 7 Material and Methods Study Area This work was carried out with samples from the margin of Magdalena region located on the peninsula of Baja California on the Pacific Ocean side (Figure 1). This area is affected by hydrographic features that determines the California Current that extends approximately between 48 ° and 23 ° N. Its circulation is controlled by the cell of high atmospheric pressure in the North Pacific and the cells of low pressure in the Aleutians. The average speed of the current is less than 25 cm s-1, the average surface temperature in winter is ~ 13 º C, while in summer is about 20 º C. The wind system promotes the appearing of upwelling which promotes high primary productivity along the stream (Lynn and Simpson, 1987). Figure 1. Study area showing the margin of Magdalena. From the biogeochemical point of view, Magdalena margin are characterized by high primary productivity, favouring the development of OMZ (O2 <2μmol/kg) (Fig. 2) located between 400 and 800 m depth (van -Geen et al., 2003; Carriquiry and Sánchez, 2007). This OMZ has beenwell described in the work of accumulation of organic carbon and calcium carbonate by Sanchez et al. (2013) 14 related with the occurrence of important phenomena of upwelling in this area (Lynn and Simpson, 1987). In the last 5000 years there has been an increase of OC and N, which is consistent with previous works (Carptanis et al 2011, Ortiz et al., 2004) Table 3. Reported values of %C, %N and δ13C in zones under influence of an OMZ. References Location (depth) %OC %N δ13C Pichevin (2010) Nicaragua (863m) 7.5±0.4 0.8±0.06 -20.4 ± 0.3 Tehuantepec (719 m) 5.2±0.5 0.56±0.08 -19.01±0.1 Arellano (2011) Mazatlán (454 m) 6.3±1.0 0.67±0.1 Hendy (2004) Pta. Concepción (955 m) 2.5±0.2 Ricuarte (2013) Bahia de La Paz (415 m) 3.7±0.7 0.58±0.1 -20.6±0.9 %OC Max Min Addison (2012) Alaska goulf (680 m) 0.5 0.9 0.3 One possibility for the inconsistent results using Schultz and Calder (based on δ13C) and Perdue Koprivnjak (based on C:N and N:C ratios) could be due to those terrestrial plants or phytoplankton organisms that are not included in the present estimations. Consequently, marine and terrestrial C: N, N:C and δ13C standards should be revised. Otherwise, efforts for producing a more precise determination of the origin of the organic compounds found in the sediments, could be necessary. For example, OM may be analyzed for the presence of long chain hydrocarbons typical in terrestrial plant tissues (Meyers et al., 2001) Conclussions In the present work the variations in the composition of the OM in sediments collected in the margin of Magdalena corresponding with the last 5000 years have been established. Moreover, it has been proved that the highest input of OM is from marine primary production and this source is the dominant trend observed through the time period. Although an important part of the previous work in the area has been carried out using δ13C and C:N ratio, new tracers including N:C ratio, quantification of chemical species as long chain hydrocarbons, etc. will be necessary in future works in order to clarify the variations of OM in a short time scale. More efforts are required to define properly methods to calculate the dominant sources of OM.. 15 Acknowledgments I wish to thank the Faculty of Marine Sciences for the formation I have been given during the degree in Marine Sciences. The University of Las Palmas de Gran Canaria and the mobility program in Latin America – EEUU for giving me the opportunity to do this work abroad and to discover the wonders of Baja California Sur, Mexico. To the Research Center for Marine Sciences (CICIMAR) and IPN for allowing me to work in their facilities togetuer with qualified staff. My enterprise tutor, Research and Production II tutor and TFG’s co-tutor, Dr. Alberto Sánchez González for his help and support given to me during the development of this work in its research group. And of course to M ª Dolores Caballero Gelado for her invaluable work as a mentor and guide me in this project. References Addison, J. A., Finney B. P., Dean W. E., Davies M. H., Mix A. C, Stoner J. S., and Jaeger J. M. (2012), Productivity and sedimentary d15N variability for the last 17,000 years along the northern Gulf of Alaska continental slope, Paleoceanography, 27, PA1206, doi:10.1029/2011PA002161. Arellano Torres E., Pichevin L. and Ganeshram R. S., 2011. High-resolution opal records from the Eastern Tropical Pacific provide evidence or silicic acid leakage from HNLC regions during glacial periods.Quaternary Science Reviews 30, 1112-1121, doi: 10.1016/j.quascirev.2011.02.00 Arnarson T.S. and Keil R.G. 2007. Changes in organic matter–mineral interactions for marine sediments with varying oxygen exposure times. Geochimica et Cosmochimica Acta.71: 3545-3556. Cartapanis O., Tachikawa K. and Bard E. 2011. Northeastern Pacific oxygen minimum zone variability over the past 70 kyr: Impact of biological production and oceanic ventilation. Paleoceanography, 26, PA4208, doi:10.1029/2011PA002126. Dubois S., Savoye N., Grémare A., Plus M., Charlier K., Beltoise A. and Blanchet H. 2012. Origin and composition of sediment organic matter in a coastal semi-enclosed ecosystem: An elemental and isotopic study at the ecosystem space scale. Journal of Marine Systems. 94: 64-73. Guíñez M., Valdés J. and Siffedine A. 2010. Variabilidad espacial y temporal de la materia orgánica sedimentaria, asociada a la Zona de Mínimo Oxígeno (ZMO), en un ambiente costero del norte de la corriente de Humboldt, bahía de Mejillones, Chile. Latinoamerican Journal of Aquatic Research. 38: 242-253. 16 Hendy, I. L.,. Pedersen T. F, Kennett J. P. and Tada R. (2004), Intermittent existence of a southern Californian upwelling cell during submillennial climate change of the last 60 kyr, Paleoceanography, 19, PA3007, doi:10.1029/2003PA000965. Hu J., Peng P., Jia G., Mai B. and Zhang G. 2006. Distribution and sources of organic carbon, nitrogen and their isotopes in sediments of the subtropical Pearl River estuary and adjacent shelf, Southern China. Marine Chemistry.98: 274-285. Hu J., Sun X., Peng zz G. and Chivas A.R. 2009. Spatial and temporal variation of organic carbon in the northern South China Sea revealed by sedimentary records Jianfang. Quaternary International. 206: 46-51. Lynn, R. J., & Simpson, J. J. 1987. The California Current System: The seasonal variability of its physical characteristics. Journal of Geophysical Research: Oceans. 92: 12947-12966. Marchitto, T. M., Lehman S. J., Ortiz J. D., Flückiger J. and van Geen A., 2007. Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise, Science: 316, 1456-1459 Meyers, P. A., and Teranes, J. L., 2001. Sediment organic matter. Tracking environmental change using lake sediments, 2: 239-269 Ortiz J.D., DelViscio J., Dean W. Carriquiry J.D., Marchitto T., Zeng Y. and van Geen A. 2004. Enhanced marine productivity off western North America during warm climate intervals of the past 52 k.y. Geology, 32, 521-524, Perdue E.M. and Koprivnjak J.F. 2007. Using the C/N ratio to estimate terrigenous inputs of organic matter to aquatic environments. Estuarine, coastal and Self Science. 73: 65-72. Pichevin, L. E., Ganeshram R. S., Francavilla S., Arellano-Torres E., Pedersen T. F., and Beaufort L. (2010), Interhemispheric leakage of isotopically heavy nitrate in the eastern tropical Pacific during the last glacial period. Paleoceanography, 25: PA1204, doi:10.1029/2009PA001754. Ricaurte-Villota C, González-Yajimovich O, Sánchez, A., 2013. Coupled Response of Rainfall and Denitrification to Solar Forcing during the Holocene in Alfonso Basin. Ciencias Marinas 39: 151-164 Rodríguez-Sanz L., Mortyn P.G., Herguera J.C., and Zahn R. 2013. Hydrographic changes in the tropical and extratropical Pacific during the last deglaciation. Paleoceanography. 28:529-538 Sánchez A, González-Yajimovich O., Balart E., B. López-Ortiz E., Aguíñiga-García S. and Ortiz-Hernández M.C. 2013. Acumulación de carbono orgánico total y carbonato de calcio en la zona de oxígeno mínimo del Pacífico nororiental mexicano. Revista Mexicana de Ciencias Geológicas, 30: 222-232. 17 Sánchez A. and Carriquiry J. 2007. Acumulación de Corg, Norg, Porg y BSi en la margen de Magdalena, BCS (México), durante los últimos 26 ka. Ciencias Marinas.33: 23-25 Sánchez A. and Carriquiry J. 2007. Flujos de carbono orgánico sedimentario a lo largo del margen continental del Pacífico Nororiental Mexicano durante los últimos 50,000 años. En: B. Hernández-De la Torre, G. Gaxiola-Castro, G. (eds.), Carbono en Ecosistemas Acuáticos de México, INE, CICESE. Sánchez A. and Carriquiry J. 2010. Ópalo biogénico sedimentario: etapas isotópicas marinas 1– 5. En: G. Gaxiola, R. Durazo (eds.), Dinámica del Ecosistema Pelágico frente a Baja California: 1997-2007, INE, CICESE. Sánchez A., Carriquiry J. and López-Ortiz E. 2010. Variabilidad climática y la acumulación de carbono orgánico en el sector sur de la Corriente de California durante las etapas isotópicas marinas 1, 2 y 3. Boletín de la Sociedad Geológica Mexicana. 62: 391-398. Sánchez A., López-Ortiz B.E., Aguíñiga-García S. and Balart E. 2013.Distribution and composition of organic matter in sediments of the oxygen minimum zone of the Northeastern Mexican Pacific: paleoceanographic implications. Journal of Iberian Geology, 39, 111-120. Smith S.V., Ibarra-Obando S.E., Díaz-Castañeda V., Aranda-Manteca F.J. Carriquiry J.D., Popp B.N. and Gonzalez-Yajimovich O 2008.Sediment Organic Carbon in Todos Santos Bay, Baja California, Mexico. Esuaries and Coast. 31: 719-727. van Geen A., Zheng Y., Bernhard J.M., Cannariato K.G., Carriquiry J., Dean W.D., Eakins B.W., Ortiz J.D. and Pike J. 2003. On the preservation of laminated sediments along the western margin of North America. Paleoceanography, 18: (4), 1098, doi:10.1029/2003PA000911, 2003. Zonneveld K.A.F., Versteegh G.J.M., Kasten S., Eglinton T.I., Emeis K.C., Huguet C., Koch B.P., de Lange G.J., de Leeuw J.W., Middelburg J.J., Mollenhauer G., Prahl F.G., Rethemeyer J., and Wakeham S.G. 2010. Selective preservation of organic matter in marine environments; processes and impact on the sedimentary record. Biogeoscience. 7:483-511 Web: World Ocean Circulation Experiment Global Data Resource <http://www.nodc.noaa.gov/woce/wdiu/> 18 Memoria final del TFG GRADO EN CIENCIAS DEL MAR. ASIGNATURA: 40630 – Trabajo Fin de Grado 1. Descripción de las actividades desarrolladas durante la realización del TFT El trabajo fue realizado en el departamento de Oceanología, en los laboratorios de Química Orgánica y Química Inorgánica a cargo del Dr. Alberto Sánchez González. Durante mi estancia me encargué de: - Pretratamiento y tratamiento de muestras de sedimento: a) Secado de muestras en estufa a 50º C. b) Homogenización de las mismas con mortero y almacenado en tubos de Eppendorf. c) Digestiones ácidas con ácido clorhídrico al 3,7% (1 ml por cada 4 gramos de sedimento aproximadamente y dejar actuar un día a temperatura ambiente) para análisis de carbono. Se repetía 3 veces la adición de ácido y al cuarto día se pasaba al enjuagado con agua destilada en la centrifugadora (20 minutos a 4000 rpm a 25ºC). d) Por último pesado y empaquetado para el análisis, el cual consiste en el uso de cápsulas de estaño donde se introduce la cantidad de sedimento pertinente para el análisis, en mi caso 5 mg para nitrógeno y entre 1 y 3 mg para carbono. Luego se cierran esas cápsulas con sumo cuidado haciendo uso de pinzas y están listas para el análisis. - Calibrado de equipos analíticos: siendo el espectrofotómetro del visible (modelo Spectronic 200, casa comercial Thermo Scientific), el espectrofotómetro de masas (modelo Delta V Plus, casa comercial Thermo Scientific y el analizador elemental de combustión (casa comercial Costech Instruments). - Análisis de muestras por duplicado: un análisis para nitrógeno y otro para carbono. Almacenamiento de datos con Excel y procesamiento de datos con el software del analizador elemental (Isodat). - Revisión bibliográfica de artículos científicos relacionados con la temática de mi TFG . 2. Formación recibida: Durante los meses de prácticas, fui capacitado en distintas técnicas de pretratamiento y tratamiento de muestras, al igual que en el calibrado de los aparatos analíticos como el espectrofotómetro de masas y el analizador elemental. También tuve la oportunidad de practicar técnicas aprendidas durante el Grado. Técnicas nuevas aprendidas durante el TFG: - Homogenización con mortero 19 - Pesado y empaquetado de muestras solidas - Uso de analizador elemental y espectrofotómetro de masas. Técnicas aprendidas durante el Grado de Ciencias del Mar y aplicadas durante el TFG: - Uso de espectrofotómetro - Secado de muestras - Enjuagado con centrifugadora - Uso del material común del laboratorio - Limpieza y esterilizado de material de laboratorio tras su uso. También asistí semanalmente a seminarios impartidos en el centro de investigación con distintas temáticas relacionadas con el mar: pesquerías, migración de mamíferos marinos, distribución de elementos traza en el Golfo de California, dinámica de corrientes en el margen pacifico de Baja California, etc. Bajo recomendación de mi tutor de empresa, acudí a 4 clases sobre isotopos estables centradas en el análisis de isótopos de 18O, 13C, 15N en matrices orgánicas y sedimentarias. Estas clases eran impartidas por mi tutor de empresa y estaban relacionadas con mi trabajo de investigación ya que usaba el análisis de isótopos de 13C, 15N y la razón N:C en sedimentos para determinar el aporte terrestre de materia orgánica al margen de Magdalena en los últimos 4000 años aproximadamente. 3. Nivel de integración e implicación dentro del departamento y relaciones con el personal. El nivel de integración e implicación con el personal del departamento y el laboratorio fue bastante satisfactorio. Todos se mostraron receptivos ante mis dudas y sugerencias, y fueron muy atentos formándome para las labores que realicé durante mi estancia. El departamento se componía de aproximadamente 26 personas, pero sólo tuve una relación más estrecha con mi tutor y su grupo de investigación, la jefa de laboratorio, el técnico superior del laboratorio y alumnos de maestría (máster). Los descansos facilitaron la integración personal con los otros alumnos de maestría y las salidas de campo con los demás grupos de investigación. En los seminarios conocí a distintos profesores de otros departamentos y en las clases de isótopos entablé relación con otros alumnos de máster y doctorado. Gracias a ello pude conocer los distintos trabajos que realizaban y la variedad de usos que le daban al análisis de isotopos: análisis climáticos en matrices coralinas con 18O, determinación de alimentación en tiburones y tortugas con isótopos de 15N, determinación de fuentes de contaminación con isótopos de 15N. 4. Aspectos positivos y negativos más significativos relacionados con el desarrollo de las prácticas. 20 Aspectos positivos: aprender sobre el trabajo que existe detrás del mundo de la investigación, y valorar dicho trabajo. El haber trabajado en equipo y de manera autónoma, con las responsabilidades que acarrean ambas situaciones: Trabajar en equipo me ha permitido relacionarme con el resto del laboratorio y con otros grupos de investigación y tener una visión más holística. Además, tienes las responsabilidad de que tu equipo de trabajo y tus superiores dependen de tu trabajo al igual que yo dependo del suyo. En cambio trabajar solo me ha aportado más disciplina de trabajo y más responsabilidad a la hora de tratar muestras con las que desarrollas tu investigación, pues los despistes y descuidos pueden frenarte o incluso obligarte a reiniciar el trabajo. También te da más libertad a la hora de optimizar técnicas, siempre y cuando no alteren los resultados. Aspectos negativos: me gustaría haber aprendido más variedad de técnicas experimentales durante el transcurso de mis prácticas. 5. Valoración personal del aprendizaje conseguido a lo largo de la práctica. Me ha parecido una experiencia enriquecedora desde el punto de vista profesional, académico y personal: - Profesional: conocer el trabajo que hay detrás de todos los resultados que vemos en el papel o presentaciones en pantallas y la dedicación y responsabilidad que requiere la producción de datos científicos de calidad. - Académico: aprender técnicas de laboratorio y los principios teóricos en los que se basan, poder usar lo aprendido durante el curso en un ámbito más laboral y comprender el fin del trabajo realizado. - Personal: El tratar con otras personas en el grupo de investigación y fuera de él, intercambiar conocimientos de nuestro trabajo y poder discutir acerca de ellos, y conocer las motivaciones y los objetivos que los impulsan a trabajar en el ámbito de la investigación marina. Además, al realizar las prácticas externas y el TFG en Baja California Sur, México me ha permitido conocer la cultura de este país, su forma de vida, su deliciosa gastronomía y la cantidad de vida salvaje que se observa cerca de la ciudad. Sus hermosas playas donde acampar y las aguas repletas de biodiversidad, desde pequeños peces globo hasta grandes tiburones ballena. Y por supuesto compartir todas estas experiencias con la encantadora gente de México que he conocido y con la que he entablado amistad. Sinceramente gracias a la asignatura y lo aprendido en ella he adquirido una mayor confianza y seguridad a la hora de desempeñar el trabajo de laboratorio y de campo.