Biological interactions between fish and jellyfish in the northwester Mediterranean

Tesi per compendi de publicacions, amb diverses seccions retallades per drets dels editors.Jellyfish are important components of marine ecosystems, being a key link between lower and higher trophic levels. Jellyfish blooms occur sporadically and unpredictably in coastal areas and often have important socio-economic consequences for fisheries and tourism. This PhD thesis addresses some questions regarding the potential impact, positive and/or negative, that jellyfish have on fish populations in the Catalan coast (NW Mediterranean). Firstly, the natural diet of one of the most abundant jellyfish in the area, the scyphomedusa Pelagia noctiluca, was studied analyzing its gut contents and conducting biomarker analyses (stable isotopes and fatty acids). These results were complemented with laboratory experiments to calculate their digestion times and also with the records of fish larvae and jellyfish abundances in the field. All together, these results were used to estimate the potential feeding impact of P. noctiluca on fish eggs and larvae and competition between both groups of organisms. Results suggest that the potential consumption of ichthyoplankton by the jellyfish and competition between them may be high. Secondly, the association between the jellyfish Rhizostoma pulmo and Cotylorhiza tuberculata and the carangid fishes Trachurus mediterraneus, Trachurus trachurus and Caranx rhonchus was studied in detail. For this purpuse, field observations of jellyfish and their hosted fish were carried out during summer to describe fish behavior. Moreover, laboratory experiments were performed to determine the survival capability of the jellyfishassociated fish to the venom of their hosts. Finally, biomarker analyses were conducted to understand the significance of the association. All this information demonstrated the benefit of the association for the fish.Las medusas son componentes importantes de los ecosistemas marinos ya que son un vínculo clave entre el zooplancton más pequeño y los niveles tróficos superiores. Las proliferaciones de medusas ocurren esporádica e impredeciblemente en áreas costeras y con frecuencia tienen importantes consecuencias socioeconómicas para la pesca y el turismo. Esta tesis doctoral aborda algunas cuestiones relacionadas con el potencial impacto de las medusas, tanto positivo como negativo, sobre las poblaciones de peces en la costa catalana (NO Mediterráneo). En primer lugar, se estudió la dieta natural de una de las medusas más abundante en la zona, Pelagia noctiluca, analizando su contenido estomacal y sus biomarcadores (isótopos estables y ácidos grasos). Estos resultados se complementaron con sus tiempos de digestión (obtenidos mediante experimentos de laboratorio) y también con las abundancias en mar abierto de larvas de peces y medusas. En conjunto, estos resultados demostraron que el potencial impacto de depredación de P. noctiluca sobre huevos y larvas de peces es alto y que existe una probable competencia entre ambos grupos por el alimento. En segundo lugar, se estudió la asociación entre las medusas Rhizostoma pulmo y Cotylorhiza tuberculata y los peces carángidos Trachurus mediterraneus, Trachurus trachurus y Caranx rhonchus. Para ello, se estudió durante el período de verano el comportamiento en el mar de los peces asociados. Además, se realizaron experimentos de laboratorio para determinar la capacidad de supervivencia de estos peces al veneno de sus medusas anfitrionas. Finalmente, se realizaron análisis de biomarcadores para comprender la importancia de estas asociaciones. Toda esta información demostró el beneficio obtenido por los peces cuando se asocian a medusas.Postprint (published version

Interacciones biológicas entre medusas y peces y sus implicaciones ecológicas en el Mediterráneo Noroccidental

Memoria de tesis doctoral presentada por Uxue Tilves Matheu para obtener el título de Doctora en Ciencias del Mar por la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección de la Dra. Ana María Sabatés Freijó y de la Dra. Verónica Lorena Fuentes del Institut de Ciències del Mar (ICM-CSIC).-- 149 pages, appendices[EN] Jellyfish are important components of marine ecosystems, being a key link between lower and higher trophic levels. Jellyfish blooms occur sporadically and unpredictably in coastal areas and often have important socio-economic consequences for fisheries and tourism. This PhD thesis addresses some questions regarding the potential impact, positive and/or negative, that jellyfish have on fish populations in the Catalan coast (NW Mediterranean). [...][ES] Las medusas son componentes importantes de los ecosistemas marinos ya que son un vínculo clave entre el zooplancton más pequeño y los niveles tróficos superiores. Las proliferaciones de medusas ocurren esporádica e impredeciblemente en áreas costeras y con frecuencia tienen importantes consecuencias socioeconómicas para la pesca y el turismo. Esta tesis doctoral aborda algunas cuestiones relacionadas con el potencial impacto de las medusas, tanto positivo como negativo, sobre las poblaciones de peces en la costa catalana (NO Mediterráneo). [...]This student has been supported by a pre-doctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness). The research carried out in the present study has been developed in the frame of the FISHJELLY project, CTM2010-18874 and CTM2015-68543-RPeer Reviewe

Biological interactions between fish and jellyfish in the northwester Mediterranean

Tesi per compendi de publicacions, amb diverses seccions retallades per drets dels editors.Jellyfish are important components of marine ecosystems, being a key link between lower and higher trophic levels. Jellyfish blooms occur sporadically and unpredictably in coastal areas and often have important socio-economic consequences for fisheries and tourism. This PhD thesis addresses some questions regarding the potential impact, positive and/or negative, that jellyfish have on fish populations in the Catalan coast (NW Mediterranean). Firstly, the natural diet of one of the most abundant jellyfish in the area, the scyphomedusa Pelagia noctiluca, was studied analyzing its gut contents and conducting biomarker analyses (stable isotopes and fatty acids). These results were complemented with laboratory experiments to calculate their digestion times and also with the records of fish larvae and jellyfish abundances in the field. All together, these results were used to estimate the potential feeding impact of P. noctiluca on fish eggs and larvae and competition between both groups of organisms. Results suggest that the potential consumption of ichthyoplankton by the jellyfish and competition between them may be high. Secondly, the association between the jellyfish Rhizostoma pulmo and Cotylorhiza tuberculata and the carangid fishes Trachurus mediterraneus, Trachurus trachurus and Caranx rhonchus was studied in detail. For this purpuse, field observations of jellyfish and their hosted fish were carried out during summer to describe fish behavior. Moreover, laboratory experiments were performed to determine the survival capability of the jellyfishassociated fish to the venom of their hosts. Finally, biomarker analyses were conducted to understand the significance of the association. All this information demonstrated the benefit of the association for the fish.Las medusas son componentes importantes de los ecosistemas marinos ya que son un vínculo clave entre el zooplancton más pequeño y los niveles tróficos superiores. Las proliferaciones de medusas ocurren esporádica e impredeciblemente en áreas costeras y con frecuencia tienen importantes consecuencias socioeconómicas para la pesca y el turismo. Esta tesis doctoral aborda algunas cuestiones relacionadas con el potencial impacto de las medusas, tanto positivo como negativo, sobre las poblaciones de peces en la costa catalana (NO Mediterráneo). En primer lugar, se estudió la dieta natural de una de las medusas más abundante en la zona, Pelagia noctiluca, analizando su contenido estomacal y sus biomarcadores (isótopos estables y ácidos grasos). Estos resultados se complementaron con sus tiempos de digestión (obtenidos mediante experimentos de laboratorio) y también con las abundancias en mar abierto de larvas de peces y medusas. En conjunto, estos resultados demostraron que el potencial impacto de depredación de P. noctiluca sobre huevos y larvas de peces es alto y que existe una probable competencia entre ambos grupos por el alimento. En segundo lugar, se estudió la asociación entre las medusas Rhizostoma pulmo y Cotylorhiza tuberculata y los peces carángidos Trachurus mediterraneus, Trachurus trachurus y Caranx rhonchus. Para ello, se estudió durante el período de verano el comportamiento en el mar de los peces asociados. Además, se realizaron experimentos de laboratorio para determinar la capacidad de supervivencia de estos peces al veneno de sus medusas anfitrionas. Finalmente, se realizaron análisis de biomarcadores para comprender la importancia de estas asociaciones. Toda esta información demostró el beneficio obtenido por los peces cuando se asocian a medusas

Biological interactions between fish and jellyfish in the northwester Mediterranean

Jellyfish are important components of marine ecosystems, being a key link between lower and higher trophic levels. Jellyfish blooms occur sporadically and unpredictably in coastal areas and often have important socio-economic consequences for fisheries and tourism. This PhD thesis addresses some questions regarding the potential impact, positive and/or negative, that jellyfish have on fish populations in the Catalan coast (NW Mediterranean). Firstly, the natural diet of one of the most abundant jellyfish in the area, the scyphomedusa Pelagia noctiluca, was studied analyzing its gut contents and conducting biomarker analyses (stable isotopes and fatty acids). These results were complemented with laboratory experiments to calculate their digestion times and also with the records of fish larvae and jellyfish abundances in the field. All together, these results were used to estimate the potential feeding impact of P. noctiluca on fish eggs and larvae and competition between both groups of organisms. Results suggest that the potential consumption of ichthyoplankton by the jellyfish and competition between them may be high. Secondly, the association between the jellyfish Rhizostoma pulmo and Cotylorhiza tuberculata and the carangid fishes Trachurus mediterraneus, Trachurus trachurus and Caranx rhonchus was studied in detail. For this purpuse, field observations of jellyfish and their hosted fish were carried out during summer to describe fish behavior. Moreover, laboratory experiments were performed to determine the survival capability of the jellyfishassociated fish to the venom of their hosts. Finally, biomarker analyses were conducted to understand the significance of the association. All this information demonstrated the benefit of the association for the fish.Las medusas son componentes importantes de los ecosistemas marinos ya que son un vínculo clave entre el zooplancton más pequeño y los niveles tróficos superiores. Las proliferaciones de medusas ocurren esporádica e impredeciblemente en áreas costeras y con frecuencia tienen importantes consecuencias socioeconómicas para la pesca y el turismo. Esta tesis doctoral aborda algunas cuestiones relacionadas con el potencial impacto de las medusas, tanto positivo como negativo, sobre las poblaciones de peces en la costa catalana (NO Mediterráneo). En primer lugar, se estudió la dieta natural de una de las medusas más abundante en la zona, Pelagia noctiluca, analizando su contenido estomacal y sus biomarcadores (isótopos estables y ácidos grasos). Estos resultados se complementaron con sus tiempos de digestión (obtenidos mediante experimentos de laboratorio) y también con las abundancias en mar abierto de larvas de peces y medusas. En conjunto, estos resultados demostraron que el potencial impacto de depredación de P. noctiluca sobre huevos y larvas de peces es alto y que existe una probable competencia entre ambos grupos por el alimento. En segundo lugar, se estudió la asociación entre las medusas Rhizostoma pulmo y Cotylorhiza tuberculata y los peces carángidos Trachurus mediterraneus, Trachurus trachurus y Caranx rhonchus. Para ello, se estudió durante el período de verano el comportamiento en el mar de los peces asociados. Además, se realizaron experimentos de laboratorio para determinar la capacidad de supervivencia de estos peces al veneno de sus medusas anfitrionas. Finalmente, se realizaron análisis de biomarcadores para comprender la importancia de estas asociaciones. Toda esta información demostró el beneficio obtenido por los peces cuando se asocian a medusas

Alimentación del ctenóforo invasor Mnemiopsis leidyi: predación sobre larvas de peces

XVII Simposio Ibérico de Estudios de Biología Marina (SIEBM), 11-14 September 2012, Donostia-San SebastiánMnemiopsis leidyi es una especie de ctenóforo nativo de la costa Atlántica de América (Purcell et al. 2001). Esta especie tiene una alta tolerancia a las condiciones ambientales, pudiendo habitar en aguas con temperaturas que varían de 0ºC a 32ºC y salinidades desde ≤ 2 a 38. Dada esta característica, M.leidyi ha sido capaz de invadir diferentes mares del mundo (Costello et al. 2012) y su presencia ha tenido un importante impacto negativo en los ecosistemas de algunas de las zonas invadidas. En estas áreas, se ha observado una reducción de la biomasa del zooplancton, cambios en su composición, e incluso el colapso de las pesquerías debido a su depredación sobre larvas y huevos de peces, tal como ocurrió en el Mar Negro (Shiganova, 1998; Shiganova & Bulgakova, 2000; Shiganova, 2005; Roohi et al., 2008; Roohi et al., 2010). En julio del 2009 fue reportada por primera vez la presencia de M. leidyi a lo largo de la costa mediterránea española. Durante el verano del 2010 éste ctenóforo reapareció en el Delta del Ebro, esta vez sobreviviendo al invierno, lo que sugiere un establecimiento de la especie en la zona (Marambio et al. en preparación). Dadas las características de esta especie, es de gran interés la interacción que M. leidyi pueda tener sobre las poblaciones de peces costeros. Para ello, es necesario determinar las tasas de alimentación sobre larvas de peces. Con este objetivo, se han realizado una serie de experimentos con larvas de dos especies de peces, Sparus aurata y Dicentrarchus labrax. Se ha medido el tiempo de digestión de ambas presas bajo diferentes condiciones de temperatura y salinidad. Las condiciones han sido: 35; 37,7 y 38 de salinidad y en cada una de las salinidades 4 temperaturas: 12, 21, 25 y 28ºC, valores que se ajustan a las condiciones que se encuentran a lo largo del año en la costa Catalana. Los resultados indican que el tiempo de digestión de M. leidyi puede variar entre 4 y 6 horas. Se observan diferencias entre ambas especies de peces, siendo el tiempo de digestión de S. aurata menor que el de D. labrax. También se observan diferencias entre las distintas condiciones experimentales. Así, el tiempo de digestión es menor a altas temperaturas y baja salinidad. La información sobre los tiempos de digestión es esencial para poder inferir las tasas de alimentación de M.leidyi junto con la información de su dieta natural a partir del estudio de los contenidos estomacales. A su vez estos resultados constituyen los primeras datos sobre la interacción entre este gelatinoso y larvas de pez siendo además estas aproximaciones una importante contribución a los aspectos ecológicos de esta especie invasora en las costas EspañolasPeer reviewe

Trophic ecology of Trachurus mediterraneus juveniles associated with the jellyfish Rhizostoma pulmo and Cotylorhiza tuberculata

9 pages, 6 figures, 2 tablesThis study analyses the trophic ecology of the horse mackerel (Trachurus mediterraneus) juveniles associated with two jellyfish species, Rhizostoma pulmo and Cotylorhiza tuberculata, in the NW Mediterranean. The aim was to know whether the natural diet composition of the hosted fish could be influenced by the jellyfish species and to explore if the fish could feed on the host jellyfish. Samplings were carried out off the coast of Barcelona in summer 2011 at depths of up to 10 m. Juveniles associated with C. tuberculata showed a higher feeding incidence and number of ingested prey than those associated with R. pulmo. The relative importance of the different prey varied depending on the jellyfish species with which fish were associated. In juveniles associated with C. tuberculata, the diet was similar to the composition of the ambient zooplankton, with the cladocera Evadne spp. and Calanoida copepods as the most important prey. However, juveniles associated with R. pulmo fed mainly on Calanoida and Harpacticoida copepods. These differences could be related to the depth-associated behaviour of each jellyfish species, with R. pulmo particularly making deeper living plankton accessible to the horse mackerel juveniles. The presence of nematocyst cells in the juvenile gut contents suggests that they fed on the host jellyfish, either directly on the jellyfish tissue or accidentally when they remove the prey captured by the jellyfish oral arms. Our results provide a better understanding of the associations between jellyfish and juvenile fish which can have important effects on fish population dynamicsThis work was supported by the Spanish Ministry of Economy and Competitiveness (CTM2010-18874 and CTM2015-68543-R). JM was supported by a predoctoral FI-AGAUR fellowship of the University and Research Grants Management Agency (AGAUR) of the Government of Catalonia (Generalitat de Catalunya) (FI_B_00412)Peer Reviewe

Characterization of the association between fish juveniles and jellyfish in the Catalan coast (NW Mediterranean)

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainFish-jellyfish association is described as a temporary symbiosis believed to protect the fishes from predators and to provide them of food. Such biological interactions were studied close to Barcelona (Spain) during the summer period from 2011 to 2014. Jellyfish and their associated fishes were collected, counted, identified and measured; fish juvenile¿s behaviour was described by visual observations and videotaping; biomarkers were also analysed to determine both groups diet. Juveniles of Trachurus mediterraneus, Trachurus trachurus, and Caranx rhonchus were found associated to the scyphomedusae Rhizostoma pulmo and Cotylorhiza tuberculata. In both jellyfish species, the size of T. mediterraneus ranged between 8 and 56 mm, being small size classes (12-32 mm) predominant in C. tuberculata. No clear pattern was found between the number of fish and the medusa size but they were more abundant when swimming with C. tuberculata. Observations on juvenile behaviour showed they swam around jellyfish and they got into their oral arms when they scared. The study of these associations will help to understand the potential effect of jellyfish blooms in the survival and recruitment of some fish speciesPeer Reviewe

Trophic ecology of Pelagia noctiluca: a biomarkers study

5th International Jellyfish Bloom Symposium, 30 May to 3 June 2016, Barcelona.-- 1 pageThe syphozoan Pelagia noctiluca is one of the most abundant jellyfish in the Mediterranean Sea and it is known for being predator of zooplankton, including ichthyoplankton. Its abundance seem to be increasing in the NW Mediterranean Sea in the last decades and its impact on marine ecosystem is under continuous study. The objective of the present study is to identify the trophic relationships between ephyrae and adults of P. noctiluca and the main representative zooplankton groups (mainly fish larvae) using biomarkers (stable isotopes and fatty acids) as complementary approaches of gut contents, in order to have a broader view of these interactions. Zooplankton samples were collected using a Mocnness net and P. noctiluca specimens were individually sampled from the surface using a long hand net during the expedition FISHJELLY conducted from 17 June – 4 July 2011 all along the Catalan Coast (NW Mediterraneran). Results of linear mixing models (SIAR) showed that P. noctiluca is an omnivorous jellyfish that feed on a wide wariety of prey, showing a similar isotopic signature of fish larvae and with salps as the main food source for adults medusae and small crustaceans for ephyare. Moreover, fatty acid patterns confirmed these results, also reflecting differences in their diet composition. Zooplankton composition in the field and different feeding strategies between developmental stages would explain these differences. The similarity in the isotopic signatures between jellyfish and fish larvae suggests a competition between both groups, although predation on fish larvae has been demonstrated. The results of the different approached will be discussed on this paperPeer Reviewe

Associations between fish and jellyfish in the NW Mediterranean

14 pages, 7 figures, 4 tablesFish–jellyfish associations were studied close to Barcelona (NW Mediterranean) during the summer period from 2008 to 2014. Jellyfish and their associate juvenile fish were collected, identified, counted, and measured. Fish behaviour was described by visual field observations and laboratory experiments were performed to determine the survival of the associated fish after being in contact with the jellyfish. In addition, the possible contribution of jellyfish to the dietary composition of the fish was assessed using a combination of biomarkers. Trachurus mediterraneus, Trachurus trachurus, and Caranx rhonchus were associated with the jellyfish Rhizostoma pulmo and Cotylorhiza tuberculata. Trachurus mediterraneus was the most frequent species and their size during the association ranged between 8.4 and 66 mm standard length. The size and number of T. mediterraneus were slightly correlated with the size of R. pulmo, but not with that of C. tuberculata, although more numerous fish were found swimming with C. tuberculata. Behaviour studies showed that juvenile fish swam around jellyfish and into their oral arms seeking shelter without suffering any pain. This survival capability was corroborated by experimental work in which all the specimens of T. mediterraneus survived after being in contact with both jellyfish species. Stable isotopes and fatty acids also revealed an important contribution of R. pulmo and C. tuberculata to T. mediterraneus diet. Defining better the associations between jellyfish and juvenile fish will help to understand the effects of the association on the survival and recruitment of fish species potentially ecologically and economically relevantThis work was supported by the projects CTM2010-18874 and CTM2015-68543-R (Spanish Ministry of Economy and Competitiveness). UT was supported by a predoctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness)Peer Reviewe