Presentacion para el 9th European Marine Biology Symposium (49TH EMBS), 7-12 september 2014, S. Petersburg, Russia.-- 1 page
The latitudinal variation (35° to 28°N) in the rate of diffusive nitrate supply across the thermocline and the associated variation in the uptake rate of nitrate and ammonium in the Central Atlantic was studied. The calculated diffusive nitrate flux showed a sharp latitudinal gradient, with the lowest nitrate supply (0.00037 μ mol m −3 d −1 ) in the South Atlantic subtropical gyre and the highest values (23.5 μ mol m −3 d −1 ) between the Equator and 15°N. The uptake rate of nitrate was inhibited at high irradiance at most stations. Both nitrate and ammonium uptake rates were lowest (about 3 and 10 umol m −3 d −1 , respectively) at the southern end of the transect and increased (about 20 and 55 μ mol m −3 d −1 , respectively) towards the Equator, with this increase being much greater for ammonium than for nitrate uptake. The f ‐ratio was highest (≈0.4) just south of the Equator and lowest (≈0.03) at the southern end of the transect. The slope between total uptake rate of dissolved inorganic nitrogen and gross primary production, calculated from O 2 ‐based measurements, in surface waters (4.72 ± 1.54) was somewhat lower, but not significantly so, than the expected C/N ratio of 6.6. The average uptake rate of nitrate did not differ significantly from the average estimated diffusive supply of nitrate to the biogenic layer over the Central Atlantic. However, the nitrate uptake rate increased as the ⅓ power of the diffusive nitrate flux to the biogenic layer. As a result, nitrate uptake far exceeded (by up to 100‐fold) the nitrate flux to the biogenic layer in the stations where the supply of nitrate was lowest. The excess nitrate uptake averaged 0.65 ± 0.24 mmol NO 3 m −2 d −1 (range, 0.05–1.9 mmol NO 3 m −2 d −1 ), which must be supplied through atmospheric deposition and other perturbation events. This excess nitrate uptake is relatively large compared to the diffusive supply in the most unproductive areas, where external nitrate inputs fuel the new production. In contrast, these sources of nitrate are far less significant where high diffusive fluxes suffice to maintain high nitrate uptake rates.
The dark ocean, the waters below 200 m depth, comprises about 95% of the volume of the ocean, but its contribution to the metabolism of the ocean is poorly quantified. Here we show that the respiration rate of microplankton declines exponentially at a rate of 0.53 km −1 in the dark ocean, and is enhanced at the interface between the mesopelagic and the abyssal layers (1,000–2,000 m). The respiratory CO 2 production in the dark ocean, estimated at 20 to 33.3 Gt C yr −1 , renders it a major component of the carbon flux in the biosphere.
The meadows formed by seagrasses have characteristics that make them a suitable habitat for many species of animals. The high primary productivity of the seagrasses, augmented with that of epiphytic and benthic algae, ensures an abundant supply of organic matter that can be used as the basic energy source for more or less complicated food webs. Moreover, the three-dimensional structure of the vegetation, with its network of roots and rhizomes and often dense leaf canopy, offers hiding places that protect against predation, and also provides substrate for attachment. The vegetation structure, furthermore, confers physical and chemical qualities to the environment that may attract fauna: currents within the canopy are reduced, the sediment is stabilized and often fine grained, and irradiance conditions are modified. In this chapter we will first take a closer look at the general abundance and species richness of the fauna associated with seagrass meadows, before turning to the faunal groups that have received major attention, i.e. fishes, crustaceans and molluscs. The association of sea cows and turtles with seagrass beds will also be discussed. The significance of seagrass meadows as a habitat and foraging area is a recurrent theme in these sections. In the final part of the chapter, the ways in which the fauna affect the functioning of the seagrasses will be addressed.
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 171:97-108 (1998) - doi:10.3354/meps171097 Root production and belowground seagrass biomass Carlos M. Duarte1,*, Martín Merino2, Nona S. R. Agawin3, Janet Uri3, Miguel D. Fortes3, Margarita E. Gallegos4, Nùria Marbá5, Marten A. Hemminga5 1Centro de Estudios Avanzados de Blanes, CSIC, Camí de Santa Bárbara s/n, E-17300 Blanes, Girona, Spain 2Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, 04510 México D.F., México 3Marine Science Institute, CS, University of The Philippines, Diliman, Quezon City, The Philippines 4Departamento de Hidrobiología, Universidad Autónoma Metropolitana - Iztapalapa, Michoacán y Purísima, Col. Vicentina, AP 55-535, 09340 México D.F., México 5Netherlands Institute of Ecology, Centre for Estuarine and Coastal Ecology, Vierstraat 28, 4401 EA Yerseke, The Netherlands *E-mail: duarte@ceab.csic.es ABSTRACT: The root and rhizome biomass of the seagrass species present in 3 mixed and 2 monospecific meadows representative of different floras (Spanish Mediterranean, Mexican Caribbean, Kenyan coast, and the South China Sea off The Philippines) was examined to test for the existence of general patterns in the distribution of their biomass in the sediments, and to test a simple approach based on age determinations to estimate root production. The thickness of the roots was scaled to the thickness of the seagrass rhizomes (r = 0.92, p < 0.001). Root and rhizome biomass were high (>100 and >200 g DW m-2, respectively) for the mixed meadows examined; these belowground structures had a projected surface area often exceeding 1 m2 m-2 when roots and rhizomes were considered together, and they formed a dense web of root material comprising several hundred meters per square meter. Belowground biomass showed considerable vertical stratification within the sediments, with a tendency for the larger species to extend deeper into the sediments than smaller ones. This tendency for segregation should reduce the potential interspecific competition for sediment resources, which is likely to be greater in the uppermost layers, where the belowground biomass is more evenly distributed among species. The rate of adventitious root production on vertical shoots varied from species that produced a root on almost every node to species that produced 1 adventitious root for every 10 nodes. Root production--both on horizontal rhizomes and vertical shoots--was substantial, with the combined root production approaching, or exceeding, 1000 g DW m-2 yr-1. The resulting root turnover was quite high, with most values ranging between 2 and 10 yr-1, indicative of a characteristic turnover time of months for the root compartment. The estimates of root production derived here often exceed those of rhizome production and reach values comparable to leaf production, clearly demonstrating that root production is an important component (up to 50%) of total seagrass production. KEY WORDS: Seagrass · Roots · Rhizomes · Biomass · Production Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 171. Publication date: October 01, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.
Abstract. The relationship between the partial pressure of carbon dioxide (pCO2) and dissolved organic carbon (DOC) concentration in Brazilian lakes, encompassing 225 samples across a wide latitudinal range in the tropics, was tested. Unlike the positive relationship reported for lake waters, which was largely based on temperate lakes, we found no significant relationship for low-latitude lakes (< 33°), despite very broad ranges in both pCO2 and DOC levels. These results suggest substantial differences in the carbon cycling of low-latitude lakes, which must be considered when upscaling limnetic carbon cycling to global scales.
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 294:9-22 (2005) - doi:10.3354/meps294009 Patterns of publication effort in coastal biogeochemistry: a bibliometric survey (1971 to 2003) Jean-Pierre Gattuso1,*, Nelly A. Dawson1, Carlos M. Duarte2, Jack J. Middelburg3 1Laboratoire d'Océanographie, CNRS-Université de Paris 6, BP 28, 06234 Villefranche-sur-Mer Cedex, France2IMEDEA (CSIC-UIB), Instituto Mediterraneo de Estudios Avanzados, C/ Miquel Marques 21, 07190 Esporles (Islas Baleares), Spain3The Netherlands Institute of Ecology (NIOO-KNAW), Postbus 140, 4400 AC Yerseke, The Netherlands *Email: gattuso@obs-vlfr.fr ABSTRACT: A bibliographic database comprising 17604 references on biogeochemistry and disturbances in coastal ecosystems was compiled for the period 1971 to 2004 from the Aquatic Science and Fisheries Abstracts and the Web of Science databases. The coastal ocean received increased attention starting in the early 1990s, as shown by the increase in the rate of publication, both in absolute number (2-fold increase of the yearly rate) and relative to the publication rate of all disciplines (3-fold increase). The number of publications on each ecosystem type and the geographic location of study sites are not proportional to their respective surface area. By this measure, estuaries and the open continental shelf are, respectively, over- and under-investigated, and the research effort is disproportionately high in some areas (e.g. the North Atlantic Ocean and Mediterranean Sea, the subjects of 41% of the publications) and low in other areas (e.g. high-latitude coastal zones and the western Pacific). The cycling of inorganic nutrients is the biogeochemical process receiving the highest research effort (46% of the publications). Although controversial, exchanges with the atmosphere, including CO2, have been poorly investigated, with only 1.3% of the publications. The magnitude of scientific community publishing increased 13-fold during the period of investigation, also demonstrating the growing interest in coastal biogeochemistry and disturbances. Moreover, the lists of authors have become longer, perhaps indicating research projects wider in scope. Senior authors from 137 countries contributed papers; the EU25 and the USA contributed about 1/3 of the publications each. The number of publications per million inhabitants is highly correlated to the gross domestic product per inhabitant, but some countries perform better (the Scandinavian countries, Australia, New Zealand and Canada) or less well (Japan, the USA and Italy) than average. The number of citations of the publications is highly variable and indicates that barriers between disciplines still exist. At least 2 specialized journals (Estuaries and Estuarine, Coastal and Shelf Science) are among the most relevant journals, but Marine Ecology Progress Series is the single most important source of literature in the fields of coastal biogeochemistry and disturbances. This diagnostic should be useful to the research community and funding agencies to address the present imbalances in research allocation and to steer attention to geographical areas and processes that remain poorly investigated. Only then can the role of the coastal ocean on the global biogeochemical cycles and its response to climatic and anthropogenic disturbances be clarified. KEY WORDS: Bibliometry · Coastal ecosystems · Biogeochemistry · Disturbances · Journals · Citations · Study sites · Affiliation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 294. Online publication date: June 09, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.
Blue Carbon is a term coined in 2009 to draw attention to the degradation of marine and coastal ecosystems and the need to conserve and restore them to mitigate climate change and for the other ecosystem services they provide. Blue Carbon has multiple meanings, which we aim to clarify here, which reflect the original descriptions of the concept including (1) all organic matter captured by marine organisms, and (2) how marine ecosystems could be managed to reduce greenhouse gas emissions and thereby contribute to climate change mitigation and conservation. The multifaceted nature of the Blue Carbon concept has led to unprecedented collaboration across disciplines, where scientists, conservationists and policy makers have interacted intensely to advance shared goals. Some coastal ecosystems (mangroves, tidal marshes and seagrass) are established Blue Carbon ecosystems as they often have high carbon stocks, support long-term carbon storage, offer the potential to manage greenhouse gas emissions and support other adaptation policies. Some marine ecosystems do not meet key criteria for inclusion within the Blue Carbon framework (e.g. fish, bivalves and coral reefs). Others have gaps in scientific understanding of carbon stocks or greenhouse gas fluxes, or currently there is limited potential for management or accounting for carbon sequestration (macroalgae and phytoplankton), but may be considered Blue Carbon ecosystems in the future, once these gaps are addressed.
