Seagrass as major source of transparent exopolymer particles in the oligotrophic Mediterranean coast

Abstract. The role of seagrass, Posidonia oceanica, meadows as a source of transparent exopolymer particles (TEPs) to Mediterranean coastal waters was tested by comparing the TEP dynamics in two adjacent coastal waters in the oligotrophic NW Mediterranean Sea, one characterized by oligotrophic open-sea waters and the other accumulating seagrass leaf litter, together with an experimental examination of TEP release by seagrass litter. TEP concentrations ranged from 4.6 to 90.6 µg XG (xanthan gum) Eq L−1, with mean (±SE) values of 38.7 (± 2.02) µg XG Eq L−1 in the site devoid of seagrass litter, whereas the coastal beach site accumulating leaf litter had > 10-fold mean TEP concentrations of 487.02 (± 72.8) µg XG Eq L−1. Experimental evaluation confirmed high rates of TEP production by P. oceanica litter, allowing calculations of the associated TEP yield. We demonstrated that P. oceanica is an important source of TEPs to the Mediterranean Sea, contributing an estimated 76 Gg C as TEPs annually. TEP release by P. oceanica seagrass explains the elevated TEP concentration relative to the low chlorophyll a concentration in the Mediterranean Sea.

[1]  L. Legendre,et al.  Transparent exopolymer particles: Effects on carbon cycling in the ocean , 2017 .

[2]  Francesc Peters,et al.  Horizontal and Vertical Distributions of Transparent Exopolymer Particles (TEP) in the NW Mediterranean Sea Are Linked to Chlorophyll a and O2 Variability , 2017, Front. Microbiol..

[3]  C. Duarte,et al.  Dissolved organic carbon fluxes by seagrass meadows and macroalgal beds , 2014, Front. Mar. Sci..

[4]  N. Marbà,et al.  Mediterranean seagrass (Posidonia oceanica) loss between 1842 and 2009 , 2014 .

[5]  G. D. Falco,et al.  Morphology and composition of beach-cast Posidonia oceanica litter on beaches with different exposures. , 2012 .

[6]  T. Berman,et al.  Transparent exopolymer particle (TEP) dynamics in the eastern Mediterranean Sea , 2011 .

[7]  C. Duarte,et al.  Significance of Bacterial Activity for the Distribution and Dynamics of Transparent Exopolymer Particles in the Mediterranean Sea , 2010, Microbial Ecology.

[8]  Kari B. Heinonen,et al.  Production of transparent exopolymer particles (TEP) by benthic suspension feeders in coastal systems , 2007 .

[9]  G. Navarro,et al.  Distribution of TEP in the euphotic and upper mesopelagic zones of the southern Iberian coasts , 2006 .

[10]  C. Duarte,et al.  Organic carbon metabolism and carbonate dynamics in a Mediterranean seagrass (Posidonia oceanica), meadow , 2006 .

[11]  Osvin Pečar,et al.  Transparent exopolymeric particles' distribution in the northern Adriatic and their relation to microphytoplankton biomass and composition. , 2005, The Science of the total environment.

[12]  D. Thornton.  Formation of transparent exopolymeric particles (TEP) from macroalgal detritus , 2004 .

[13]  C. Duarte.  How can beaches be managed with respect to seagrass litter , 2004 .

[14]  C. Duarte,et al.  European seagrasses: an introduction to monitoring and management , 2004 .

[15]  E. Villa,et al.  Transparent exopolymer particle (TEP) dynamics in relation to trophic and hydrological conditions in the NW Mediterranean Sea , 2003 .

[16]  M. Mateo,et al.  Posidonia oceanica ‘banquettes’: a preliminary assessment of the relevance for meadow carbon and nutrients budget , 2003 .

[17]  H. Grossart,et al.  Microbial ecology of organic aggregates in aquatic ecosystems , 2002 .

[18]  J. Middelburg,et al.  Carbon and nutrient deposition in a Mediterranean seagrass (Posidonia oceanica) meadow , 2002 .

[19]  U. Passow.  Transparent exopolymer particles (TEP) in aquatic environments , 2002 .

[20]  M. Pedrotti,et al.  Non‐Redfield C:N ratio of transparent exopolymeric particles in the northwestern Mediterranean Sea , 2001 .

[21]  U. Passow,et al.  Carbon and nitrogen content of transparent exopolymer particles (TEP) in relation to their Alcian Blue adsorption , 2001 .

[22]  Carlos M. Duarte,et al.  Detrital stocks and dynamics of the seagrass Posidonia oceanica (L.) Delile in the Spanish Mediterranean , 2001 .

[23]  Carlos M. Duarte,et al.  Seagrass Biomass And Production: A Reassessment , 1999 .

[24]  C. Duarte,et al.  The Mediterranean climate as a template for Mediterranean marine ecosystems: the example of the northeast Spanish littoral , 1999 .

[25]  F. Rassoulzadegan,et al.  Conceptual models for the biogeochemical role of the photic zone microbial food web, with particular reference to the Mediterranean Sea , 1999 .

[26]  U. Passow,et al.  The role of surface‐active carbohydrates in the formation of transparent exopolymer particles by bubble adsorption of seawater , 1998 .

[27]  M. Mateo,et al.  Detritus dynamics in the seagrass Posidonia oceanica: elements for an ecosystem carbon and nutrient budget , 1997 .

[28]  C. Duarte,et al.  Spatial and temporal variations in nutrient limitation of seagrass Posidonia oceanica growth in the NW Mediterranean , 1997 .

[29]  Carlos M. Duarte,et al.  The fate of marine autotrophic production , 1996 .

[30]  Alice L. Alldredge,et al.  A dye-binding assay for the spectrophotometric measurement of transparent exopolymer particles (TEP) , 1995 .

[31]  S. Myklestad.  Release of extracellular products by phytoplankton with special emphasis on polysaccharides , 1995 .

[32]  Alice L. Alldredge,et al.  Aggregation of a diatom bloom in a mesocosm: The role of transparent exopolymer particles (TEP) , 1995 .

[33]  Bruce E. Logan,et al.  The abundance and significance of a class of large, transparent organic particles in the ocean , 1993 .

[34]  J. L. Hansen,et al.  Phytoplankton aggregate formation: observations of patterns and mechanisms of cell sticking and the significance of exopolymeric material , 1993 .

[35]  M. Krom,et al.  Phosphorus limitation of primary productivity in the eastern Mediterranean Sea , 1991 .

[36]  P. Peduzzi,et al.  Decomposition and significance of sea-grass leaf litter (Cymodocea nodosa) for the microbial food web in coastal waters (Gulf of Trieste, Northern Adriatic Sea) , 1991 .

[37]  Timothy R. Parsons,et al.  A manual of chemical and biological methods for seawater analysis , 1984 .