The role of stromatolites in explaining patterns of carbon, nitrogen, phosphorus, and silicon in the Sečovlje saltern evaporation ponds (northern Adriatic Sea)
- 217 Downloads
In summer 2007, biweekly benthic fluxes of the biogenic elements carbon (C), nitrogen (N), silicon (Si), and phosphorus (P) were studied in the Sečovlje saltern (salt-making facility) in the northern Adriatic Sea, Slovenia in order to determine the impact of stromatolite (“petola”) on the geochemical properties of saltern sediments.
Materials and methods
The brine and pore waters were analyzed for salinity, NH 4 + , NO 3 − , PO 4 3− , SiO 4 4− , total dissolved nitrogen, total dissolved phosphorus, and fluorescent dissolved organic matter. The sediment was analyzed for organic carbon (OC), total nitrogen (TN), total and organic phosphorus (OP), and biogenic Si concentrations, as well as values of δ 13COC and δ 15NTN.
Results and discussion
Nutrient concentrations in brine water increased along the salinity gradient due to different processes, such as the evaporative concentrations of seawater, bacterial activity, more pronounced transformation and degradation of organic matter, and regeneration of nutrients. The petola from the Sečovlje saltern, which is predominately composed of cyanobacterial and diatom communities, develops during the early evaporation stage and survives during high salinity and halite crystallization. Nitrogen fixation and P removal were the principal biogeochemical processes controlling dissolved inorganic N and P concentrations. At higher salinities, N limitation was more important. Microbes decomposed at higher salinities, and the remineralized N and P nutrients were released from surface pore waters to the brine. OP remineralization was also an important process influencing the distribution of PO 4 3− concentrations in pore waters deeper in the sediments. The increasing SiO 4 4− concentrations with increasing salinity in the brine waters were due to dissolution of diatom frustules, while the decrease in pore water SiO 4 4− was probably the consequence of microbial uptake.
This study provides a better understanding of nutrient cycling and the geochemical processes in the Sečovlje saltern.
KeywordsCyanobacteria Hypersaline environment Northern Adriatic Nutrients Stromatolites
- Canfield DE, Thamdrup B, Kristensen E (2005) Aquatic geomicrobiology. Adv Mar Biol 48:427–431Google Scholar
- Casillas-Martinez L, Gonzales ML, Fuentes-Figueroa Z, Castro CM, Nieves-Mendez D, Hernandez C, Ramırez W, Sytsma RE, Perez-Jimenez J, Visscher PT (2005) Community structure, geochemical characteristics and mineralogy of a hypersaline microbial mat, Cabo Rojo, PR. Geomicrobiol J 22:269–281CrossRefGoogle Scholar
- Coleman MU, White MA (1993) The role of biological disturbances in the production of solar salt. Seventh Symp Salt 1:623–631Google Scholar
- Faganeli J, Pezdič J, Ogorelec B, Dolenec T, Čermelj B (1999) Salt works of Sečovlje (Gulf of Trieste, northern Adriatic)—a sedimentological and biogeochemical laboratory for evaporitic environments. RMZ-Mater Geoenviron 46:491–499Google Scholar
- Giordano M, Beardall J (2006) Impact of environmental conditions on photosynthesis, growth and carbon allocation strategies of hypersaline species of Dunaliella. In Lekkas TD, Korovessis NA (eds) Proc. 1st Int Conf on the Ecological Importance of Solar Saltworks (CEISSA 06), Santorini Island, Greece, 20–22 October 2006, pp. 65–71Google Scholar
- Grasshoff PN, Ehrhardt M, Kremling K (1983) Methods of seawater analysis. Verlag Chemie, WeiheimGoogle Scholar
- Gunde-Cimerman N, Zalar P, De Hoog GS, Plemenitaš A (2000) Hypersaline waters in salterns: natural ecological niches for halophilic black yeasts. FEMS Microbiol Ecol 32:235–240Google Scholar
- Javor B (1989) Hypersaline environments - microbiology and biogeochemistry. Springer Verlag, Berlin, p 328Google Scholar
- Knoppers B, Landim de Souza WF, Landim de Souza MF, Rodriguez EG, da Cunha Viana Landim EF, Vieira AR (1996) In situ measurements of benthic primary production, respiration and nutrient fluxes in a hypersaline coastal lagoon of SE Brazil. Rev Bras Oceanogr 44:155–165Google Scholar
- Kovač N (2009) Chemical characterization of stromatolitic ‘petola’ layer (Sečovlje salt-pans, Slovenia) using FT-IR spectroscopy. Ann Ser Hist Nat 19:1–8Google Scholar
- Ladakis M, Dassenakis M, Pantazidou A (2006) Nitrogen and phosphorus in coastal sediments covered by cyanobacteria mats. J Soil Sci 6:46–54Google Scholar
- Lerman A (1979) Geochemical processes water and sediment environments. Wiley, New YorkGoogle Scholar
- Ogorelec B, Mišič M, Faganeli J (2000) Sečoveljske soline—geološki laboratorij v naravi. Ann Ser Hist Nat 10:243–252Google Scholar
- Oren A (1999) Bioenergetic aspects of halophilism. Microbiol Mol Biol Rev 63:334–348Google Scholar
- Schneider J (1979) Stromatolithic Milieus in Salinen der Nord-Adria (Sečovlje, Portorož, Jugoslawien). In: Krumbein W (ed) Oldenburger Symposium über Cyanobakterien, 1977,—Taxonomische Stellung und Ökologie. Universität Oldenburg, Oldenburg, pp 93–106Google Scholar
- Schneider J, Herrmann GA (1979) Saltworks—natural laboratories for microbiological and geochemical investigations during the evaporation of seawater. In: Coogan AH, Hauder L (eds) Fifth international symposium on salt. Northern Ohio Geological Society, Cleveland, pp 371–381Google Scholar
- Wollast R, Garrels RM (1971) Diffusion coefficient of silica in seawater. Nature 229:94–96Google Scholar