Nutrient availability as major driver of phytoplankton-derived dissolved organic matter transformation in coastal environment

Asmala, Eero; Haraguchi, Lumi; Jakobsen, Hans Henrik; Massicotte, Philippe; Carstensen, Jacob

doi:10.1007/s10533-017-0403-0

Cited by 31 publications

(33 citation statements)

References 56 publications

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“…Bacterial utilization of OM is selective, as the more bioavailable organic fractions are utilized first (Hansell 2013). This is apparent for phytoplanktonderived fresh autochthonous DOM, which is rapidly (hours-days) transformed from labile to more recalcitrant DOM by the heterotrophic bacteria (Asmala et al 2018).…”

Section: Organic Matter In the Coastal Environmentmentioning

confidence: 99%

Factors regulating the coastal nutrient filter in the Baltic Sea

Carstensen

Conley

Almroth‐Rosell³

et al. 2019

Ambio

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The coastal zone of the Baltic Sea is diverse with strong regional differences in the physico-chemical setting. This diversity is also reflected in the importance of different biogeochemical processes altering nutrient and organic matter fluxes on the passage from land to sea. This review investigates the most important processes for removal of nutrients and organic matter, and the factors that regulate the efficiency of the coastal filter. Nitrogen removal through denitrification is high in lagoons receiving large inputs of nitrate and organic matter. Phosphorus burial is high in archipelagos with substantial sedimentation, but the stability of different burial forms varies across the Baltic Sea. Organic matter processes are tightly linked to the nitrogen and phosphorus cycles. Moreover, these processes are strongly modulated depending on composition of vegetation and fauna. Managing coastal ecosystems to improve the effectiveness of the coastal filter can reduce eutrophication in the open Baltic Sea.

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Section: Organic Matter In the Coastal Environmentmentioning

confidence: 99%

Factors regulating the coastal nutrient filter in the Baltic Sea

Carstensen

Conley

Almroth‐Rosell³

et al. 2019

Ambio

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“…One possible mechanism for this is the so-called priming effect, where the introduction of labile carbon compounds (such as carbohydrates) enables utilization of other, more recalcitrant organic compounds (Guenet et al 2010;Steen et al 2016). This assumed coupling between eelgrass production and bacterial remineralization is supported by the marked increase in humic-like DOM in the units with the largest decrease in DOC concentration, which indicates the transformation of non-colored DOM to colored DOM (Shimotori et al 2009;Asmala et al 2018a). The metabolic response of the bacterial community to autochthonous DOM production is rapid; more than 50% of the DOC released by eelgrass can be remineralized on a daily basis (Ziegler and Benner 1999).…”

Section: Nutrients and Organic Mattermentioning

confidence: 99%

“…This seagrass-derived DOC is typically a highly bioavailable carbon source for heterotrophic bacteria (Ziegler and Benner 1999). Microbial processing of this autochthonous DOC changes its bulk chemical and optical characteristics rapidly, enabling the tracking of the extent of these processes within the system (Asmala et al 2018a). In addition to direct benthic-pelagic fluxes of nutrients and organic carbon, seagrasses influence various other biogeochemical processes in the sediment, including oxygen dynamics, mineralization of organic matter, ammonification, and nitrification-denitrification Kemp 1990, 1991;Marbà et al 2006;Hemminga and Duarte 2000;Boström et al 2014;Gustafsson and Norkko 2016;Staehr et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Role of Eelgrass in the Coastal Filter of Contrasting Baltic Sea Environments

Asmala

Gustafsson

Norkko

et al. 2019

Estuaries and Coasts

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Coastal ecosystems act as filters of nutrients from land to the open sea. We investigated the role of eelgrass (Zostera marina) metabolism in the coastal filter transforming nitrogen, phosphorus, and organic carbon. Field campaigns following identical methodologies were carried out at two contrasting coastal locations: the mesohaline and nutrient-rich Roskilde Fjord, Denmark, and the mesotrophic brackish Tvärminne archipelago, Finland. Over the 24-h in situ benthic incubations, we measured oxygen concentrations continuously and assessed changes in DOM characteristics and net fluxes of carbon, nitrogen, and phosphorus. Ecosystem metabolism modeled on the basis of the O 2 data showed that the systems were either net heterotrophic (Roskilde Fjord; − 1.6 and − 2.4 g O 2 m −2 day −1 in eelgrass meadow and bare sand, respectively) or had balanced primary production and respiration (Tvärminne; 0.0 and 0.2 g O 2 m −2 day −1 ). Overall, initial nutrient stoichiometry was a key factor determining benthic-pelagic fluxes of nutrients, which exacerbated the deviations from Redfield ratios of N and P, indicating an efficient use of the limiting nutrient. A net diel uptake of dissolved inorganic N was observed at both locations (− 2.3 μmol l −1 day −1 in Roskilde Fjord and − 0.1 μmol l −1 day −1 in Tvärminne). Despite minor changes in dissolved organic carbon concentrations during the incubations, a marked increase of fluorescent DOM was observed at both locations, suggesting rapid heterotrophic processing of the DOM pool. Our results underline that the biogeochemical role of eelgrass in the coastal filter is not inherent, but strongly dependent on the environmental conditions.

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“…However, since river water contains both inorganic nutrients and dissolved organic matter, freshwater inflows or flooding could either promote large or small phytoplankton cells. Moreover, where natural bacterial communities also make a significant part of the food web then the conversion of organic matter and the changes in bioavailability of it may also be critical factors (Asmala et al, 2013;Traving et al, 2017;Asmala et al, 2018). Thus overall, the phytoplankton response may be governed by the magnitude of the inflow and the inorganic nutrient and organic matter concentration in the river water.…”

Section: Introductionmentioning

confidence: 99%

Response of Coastal Phytoplankton to High Inflows of Terrestrial Matter

Paczkowska¹,

Brügel²,

Rowe

et al. 2020

Front. Mar. Sci.

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Climate change scenarios project that precipitation will increase in northern Europe, causing amplified inflows of terrestrial matter (tM) and inorganic nutrients to coastal areas. How this will affect the plankton community is poorly understood. A mesocosm experiment was carried out to investigate the influence of two levels of tM inputs on the composition, size-structure and productivity of a natural coastal phytoplankton community from the northern Baltic Sea. The tM addition caused browning of the water and decreased underwater light levels, while the concentrations of dissolved organic carbon (DOC) and inorganic nutrients increased. Microphytoplankton were promoted by tM addition, while in the controls picophytoplankton dominated the phytoplankton community. Inorganic nutrient availability was instrumental in defining the phytoplankton community composition and size-structure. As a response to tM addition, the phytoplankton increased their chlorophyll a content. This physiological adaptation helped to maintain high primary production rates at the low tM enrichment, but at the high tM load the primary production decreased as did the biomass of mesozooplankton. The ciliate biomass was high when the mesozooplankton biomass was low, indicating that a trophic cascade occurred in the system. Structural equation modeling showed that tM borne DOC promoted ciliates, while primary and bacterial production were disfavored. Thus, DOC originating from soils had an indirect negative effect on the mesozooplankton by reducing their food availability. Although, a positive correlation between heterotrophic bacteria and phytoplankton suggested coupling between phytoplankton produced carbon and heterotrophs growth. The results from our study indicate that river-borne DOC and inorganic nutrients have a large impact on the phytoplankton community, driving the system to the dominance of large diatoms. However, since river-borne humic substances cause browning of the water, phytoplankton increase their light harvesting pigments. At moderate inflow this helps to support the primary production, but at high inflows of terrestrial material the primary production will decrease. As high river inflows have been projected to be a consequence of climate change, we foresee that primary production will decrease in coastal areas in the future, and the impacts of such changes on the food web could be significant.

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Nutrient availability as major driver of phytoplankton-derived dissolved organic matter transformation in coastal environment

Cited by 31 publications

References 56 publications

Factors regulating the coastal nutrient filter in the Baltic Sea

Factors regulating the coastal nutrient filter in the Baltic Sea

Role of Eelgrass in the Coastal Filter of Contrasting Baltic Sea Environments

Response of Coastal Phytoplankton to High Inflows of Terrestrial Matter

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