Search

10th Sponge World Conference, 25-30 June 2017, Galway, Ireland.-- 1 page, The contribution of DOM to sponge feeding is now well documented1, 2 and uptake of labile DOC occurs in both high (HMA) and low (LMA) microbial abundance sponge3. In contrast, considerable DON uptake and nitrate excretion are observed only in HMA species. We used in situ and laboratory techniques to measure the dissolved and particulate nitrogen fluxes mediated by HMA and LMA sponges and constructed a partial ni- trogen budget for 14 sponges species from four different oceanic areas: North-East Pacific, North Sea, North- West Mediterranean Sea, and the Red-Sea. Regardless of the oceanographic settings, HMA sponges exhibited high plasticity in their ability to use the available dissolved nitrogen compounds. Under normal oxygenated conditions, NH4+ levels are low and most of nitrate excreted by HMA sponges is derived from full oxidation of DON; when NH4+ concentrations are high, its uptake represent an addition to the nitrification rates. The ubiquity of nitrification among the different geographical zones and the high rates of nitrate production as- sociated with HMA sponges suggest that it represents a relevant process for energy income and potentially microbial production within these sponges. We discuss the energetic consequences of these results considering the contribution of full oxidation of the organic matter for the sponge holobionts and the consequences for nutrient cycling. Our data suggest that the HMA sponges are unique among the metazoans in their nutritional plasticity and their ability to take advantage of the entire range of reduced compounds available in the water, provide them with a relevant additional energy source

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and detritus, and excreting particulate and dissolved compounds, they serve as important agents for benthic-pelagic coupling. Accurately measuring the compounds removed and excreted by suspension feeders (such as sponges, ascidians, polychaetes, bivalves) is crucial for the study of their physiology, metabolism, and feeding ecology, and is fundamental to determine the ecological relevance of the nutrient fluxes mediated by these organisms. However, the assessment of the rate by which suspension feeders process particulate and dissolved compounds in nature is restricted by the limitations of the currently available methodologies. Our goal was to develop a simple, reliable, and non-intrusive method that would allow clean and controlled water sampling from a specific point, such as the excurrent aperture of benthic suspension feeders, in situ. Our method allows simultaneous sampling of inhaled and exhaled water of the studied organism by using minute tubes installed on a custom-built manipulator device and carefully positioned inside the exhalant orifice of the sampled organism. Piercing a septum on the collecting vessel with a syringe needle attached to the distal end of each tube allows the external pressure to slowly force the sampled water into the vessel through the sampling tube. The slow and controlled sampling rate allows integrating the inherent patchiness in the water while ensuring contamination free sampling. We provide recommendations for the most suitable filtering devices, collection vessel, and storing procedures for the analyses of different particulate and dissolved compounds. The VacuSIP system offers a reliable method for the quantification of undisturbed suspension feeder metabolism in natural conditions that is cheap and easy to learn and apply to assess the physiology and functional role of filter feeders in different ecosystems., This work was supported by the Spanish Government project CSI-Coral [grant number CGL2013-43106-R to RC and MR] and by a F.P.U fellowship from "Ministerio de Educaciòn, Cultura y Deporte (MECD)" to TM. This is a contribution from the Marine Biogeochemistry and Global Change research group funded by the Catalan Government [grant number 2014SGR1029] and ISF grant 1280/13 and BSF grant 2012089 to G. Yahel.

Presentación para el 50th European Marine Biology Symposium, 21-25 September 2015, Helgoland, Germany.-- 15 pages, This work is supported by the project ENCHANGES (CGL2010-18466) from Ministerio de Economía y Competitividad of Spain. The author benefits of FPU fellowship from Ministerio de Educación, Cultura y Deporte of Spain

Memoria de tesis doctoral presentada por Teresa Maria Morganti para obtener el título de Doctora en Ciencias del Mar por la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección del Dr. Rafael Coma Bau del Centre d’Estudis Avançats de Blanes (CEAB-CSIC) y la Dra. Marta Ribes Llordés del Institut de Ciències del Mar (ICM-CSIC).-- 177 pages, 1 annexe, [EN] Sponges play important roles in the functioning of marine ecosystem in which they are abundant. These roles range from stabilizers of substrate, to acting as major link between benthic and pelagic realms by filtering large quantities of water and retaining the particles with high efficiency. Despite sponges have been the focus of much interest in the past years our knowledge on sponge physiology is still poorly understood. This study focused on ecophysiology of five of the most prominent sponge species dwelling the coralligenous community in the NW Mediterranea Sea, and employed an energetic approach to understanding the complex interactions between physiological constrains and seasonal fluctuations of environmental factors experienced by the organism under natural conditions. In this thesis, we contributed to the still limited knowledge of energetic mechanisms that regulate seasonal dynamics and elucidated divergent metabolic profiles between high microbial (HMA) and low microbial (LMA) abundance species accordingly to their different adaptive life strategies. For this purpose we examined the in situ feeding, filtering and respiration activity over annual cycle. Firstly, we started by developing a system for quantifying the particulate and dissolved compounds processed by sponges under natural conditions. In terms of feeding, we observed that all species retained plankton at high efficiency and DOC was the main source of carbon. However, the nitrogen fluxes showed a markedly different trophic niche between the two groups: HMA species mostly rely on dissolved compound as main source of N, while LMA solely rely on particulate fractions. Interestingly, natural variation of sponge pump did not follow natural temperature changes. During the period of maximum temperature the sponge pump did not reach its maximum values, suggesting that intrinsic mechanism as a decrease in choanocytes during reproductive cycle may regulate this metabolic process. On the other hand respiration clearly showed a seasonal pattern following natural temperature fluctuation. Combined, these results allowed us to estimate the overall energy budget, which appeared to be regulated by an increase of energy demand in summer as well as the availability of dissolved organic carbon fraction in the water column. Our result also showed different limited energetic profiles between HMA and LMA species accordingly to their different feeding strategies. LMA species appeared to procure sufficient energy to meet metabolic requirements for maintenance and growth by filtering suspended particulates, and dissolved fraction represented an additional input of carbon when available. On the contrary the heterotrophic nutrition in the natural environment may be insufficient to meet basal metabolic requirements in HMA species, suggesting other metabolic pathways as relevant for the energy budget of these species, [CAT] Les esponges juguen un paper important en el funcionament del ecosistemes marins on hi son abundants. Les funcions atribuïdes a les esponges son molt diverses i inclouen entre altres actuar com estabilitzadores del substrat, així com fer de lligam entre la columna d’aigua i el bentos en l’anomenat acoblament bento pelàgic; aquest procés te lloc mitjançant una captura eficient de partícules i el retorn de compostos modificats per l’activitat metabòlica de les esponges. Tot i que les esponges han estat punt de mira en l’interès científic durant els darrers anys, s’identifica encara una manca de coneixement de la seva fisiologia. Aquesta tesi es centra en l’ecofisiologia de cinc especies d’esponges emblemàtiques del coral·ligen Mediterrani. Utilitzant una aproximació energètica s’ha avaluat les interaccions entre possibles limitacions fisiològiques en les esponges i fluctuacions estacionals en els paràmetres ambientals a les que estan sotmeses en la natura. En aquesta tesi contribuïm al coneixement encara limitat dels mecanismes energètics que regulen la dinàmica estacional de les esponges així com en aportar informació sobre el perfils metabòlics divergents entre les esponges amb alta (HMA) i baixa (LMA) concentració de microbis associats segons les seves diferents estratègies adaptatives. Amb aquest objectiu examinem in situ l’alimentació, la filtració i la respiració al llarg d’un cicle anual. En primer lloc comencem desenvolupant un sistema que permeti la quantificació de compostos particulats i dissolts processats per les esponges en el seu habitat natural. En termes d’alimentació hem observat que totes les especies retenen molt eficientment el plàncton i que el carboni orgànic dissolt (DOC) es la seva principal font de carboni. Respecte als fluxos de nitrogen s´ha trobat diferents nínxols tròfics entre especies amb diferent concentració de microbis associats: especies HMA depenen bàsicament de compostos dissolts com a font de nitrogen mentre que les especies LMA depenen de la fracció particulada. Curiosament, la variació en la tassa de filtració al llarg de l’any no segueix el cicle de temperatura. El període de temperatura mes alta no va coincidir amb les tasses de filtració mes elevades suggerint que altres mecanismes intrínsecs a les esponges, com pot ser una disminució en la quantitat de coanòcits durant el cicle de reproducció, podrien regular el metabolisme de les esponges. Per altra banda la respiració ha mostrat un patró estacional seguint les fluctuacions naturals de la temperatura. La combinació d’aquests resultats ens ha permès estimar el balanç energètic global, aquest sembla estar regulat per un increment en la demanda energètica a l’estiu coincidint amb un increment en la disponibilitat de carboni orgànic dissolt en la columna d’aigua. Els nostres resultats també han mostrat diferencies en el perfil de limitació energètica entre especies HMA i LMA coincidint amb les seves diferents estratègies en la captura de nutrients. Les especies LMA sembla que obtenen suficient energia per cobrir el seu metabolisme a partir de la matèria particulada de l’aigua, essent la fracció dissolta un aportació addicional de carboni. Contràriament en especies HMA la nutrició heterotròfica sembla ser insuficient per cobrir els requeriments metabòlics basals suggerint altres vies metabòliques rellevants per cobrir el balanç energètic, The author has been supported by a FPU pre-doctoral grant from “Ministerio de Educación, Cultura y Deporte (MECD)” from December 2011 to November 2015 (AP2010-4598). The research presented in this thesis was carried out in the framework of the project En-Change [grant number CGL2013-43106R to RC and MR]