Dissolved organic matter release in a Posidonia oceanica meadow

Barrón, Cristina; Duarte, Carlos M.

doi:10.3354/meps07715

Cited by 94 publications

(103 citation statements)

References 56 publications

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“…Sampling was made near the shore, where organic matter pools could be affected by seagrass (Posidonia oceanica) DOC release (cf. Barrón & Duarte 2009). Nevertheless, nutrient concentrations, chl a, BP, and BR were all within the range of values previously measured in open water sites in the NW Mediterranean (Lemée et al 2002, Navarro et al 2004, Alonso-Saez et al 2008.…”

Section: Discussionmentioning

confidence: 99%

Temperature and phosphorus regulating carbon flux through bacteria in a coastal marine system

Kritzberg¹,

Arrieta²,

Duarte³

2010

Aquat. Microb. Ecol.

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The aim of this study was to explore the variation and regulation of bacterial carbon processing at a coastal oligotrophic site of the Island of Majorca in the Mediterranean Sea. In situ bacterial production (BP), respiration (BR), growth efficiency, and carbon demand in relation to environmental parameters were studied over an annual cycle. In addition, the response of bacterial carbon processing to an experimental resource (phosphate) and temperature manipulations was tested. While concentrations of dissolved organic carbon (DOC) and phosphorus were fairly stable over the year, BP and BR varied 65-fold and 79-fold, respectively. Addition of phosphate stimulated both BP and BR during most of the year, suggesting that phosphorus limitation keeps a tight rein on bacterial DOC utilization. Both BP and BR responded positively to a 2°C experimental increase, but at higher temperature increases BP and BR leveled off or decreased. In situ BP and BR were positively related to temperature, suggesting that elevated water temperature would yield increased BP and BR. BR responded more strongly to temperature than BP, suggesting that increased temperature may result in a decrease in bacterial growth efficiency. KEY WORDS: Bacterial carbon processing · Bacterial growth efficiency · Temperature regulation · Resource regulation · Phosphorus limitation Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 58: [141][142][143][144][145][146][147][148][149][150][151] 2010 substrates regulates bacterial C processing (Vallino et al. 1996), as total DOC pools are orders of magnitude greater than BCDs in most aquatic ecosystems. For example, some substrates require enzymatic hydrolysis before uptake (Middelboe & Sondergaard 1993), and different organic molecules exhibit different energy to C ratios, which will pose limits to bacterial utilization and growth efficiency (Vallino et al. 1996). Moreover, bacteria may regulate the catabolism of organic substrates to attain the correct intracellular stoichiometry with respect to nutrients, such that substrates with high nutrient to C ratio should be more efficiently utilized as they better satisfy the high nutrient demand of bacteria (bacterial C:N:P 50:10:1, Fagerbakke et al. 1996). As predicted by ecological stoichiometric theory, BGE has been shown to decline with increasing C:N and C:P ratios of natural organic substrates (Kroer 1993, Lennon & Pfaff 2005. When the nutrient content of the organic substrates is too low, the presence of inorganic nutrients may result in higher substrate utilization and growth efficiency (Kroer 1993, Kragh et al. 2008. On the basis of a large cross system analysis, del Giorgio & Cole (1998) concluded that BGE is controlled mainly by BP and is related to the availability of nutrients and organic C, suggesting that bacterial C processing is predominantly controlled by resources.Temperature is an ever-present factor affecting all chemical and biochemical processes and influencing bacterial C processing thr...

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Section: Discussionmentioning

confidence: 99%

Temperature and phosphorus regulating carbon flux through bacteria in a coastal marine system

Kritzberg¹,

Arrieta²,

Duarte³

2010

Aquat. Microb. Ecol.

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“…Gross primary production (GPP; mean ± SD), respiration (R) and P/R ratio (P = GPP), at each station and sampling event. GPP and R values were obtained from Apostolaki et al (2010a) se quester annually more carbon than unvegetated (i.e void of seagrass or macroalgae) communities , Barrón & Duarte 2009), implying that considerably more carbon is stored in P. oceanica than in bare sediments. In our case, the control meadow showed 9 times higher annual NCP than the adjacent unvegetated community (Apostolaki et al 2010b), emphasizing the high C sink capacity of this meadow.…”

Section: Discussionmentioning

confidence: 99%

Reduced carbon sequestration in a Mediterranean seagrass (Posidonia oceanica) ecosystem impacted by fish farming

Apostolaki¹,

Holmer

Marbà³

et al. 2011

Aquacult. Environ. Interact.

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We studied the relationship between sediment nutrient enrichment and carbon sequestration, using the ratio of gross primary production to respiration (P/R), in a fishfarming impacted and an unaffected Mediterranean seagrass (Posidonia oceanica) ecosystem in the Aegean Sea, Greece. Carbon (C), nitrogen (N) and phosphorus (P) sedimentation, nutrient pools in sediment and dissolved nutrients in pore water were significantly and positively intercorrelated, indicating close linkage between sedimentation and sediment nutrient pools in seagrass meadows. C, N and P sediment pools were significantly enhanced in the impacted meadow throughout the year, even during winter when fish farming activity was low. In the impacted sediment, the increase in C and N was higher than P, reflecting a faster remineralization and uptake of P than C and N. The ecosystem P/R ratio decreased exponentially with sediment nutrient enrichment. Threshold values are given for C, N and P sedimentation rates and sediment pools, and for N and P concentrations in pore waters, after which P/R ratio in the seagrass meadow decreases below 1, indicating a shift from autotrophy to heterotrophy with sediment nutrient enrichment. Such a regime shift indicates a loss of storage capacity of the seagrass ecosystem, jeopardizing the key role of P. oceanica as a carbon sink in the Mediterranean.

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“…Net community production (NCP) was estimated as oxygen production in the light incubation. We report estimates of NCP per 12-h period, since we did not measure nighttime community respiration, which is likely to be lower and nonlinearly related to daytime respiration (Barron and Duarte 2009). Oxygen consumption in the dark incubation was used as an estimate of community respiration (CR).…”

Section: Methodsmentioning

confidence: 99%

Partitioning of primary production among giant kelp (Macrocystis pyrifera), understory macroalgae, and phytoplankton on a temperate reef

Miller¹,

Reed²,

Brzezinski³

2010

Limnology & Oceanography

112

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We experimentally investigated the response of phytoplankton and understory macroalgae to canopies of giant kelp, Macrocystis pyrifera, by following changes in their biomass and net primary production over 17 months in 600-m 2 plots where giant kelp was continually removed or left intact and allowed to vary naturally. Production by phytoplankton was two times greater and understory algae five times greater where Macrocystis was removed relative to the intact forest. Understory biomass, but not phytoplankton biomass, was suppressed inside the forest, leading to a higher magnitude of effect on net primary production (NPP) by understory relative to phytoplankton. Following a natural decline of the Macrocystis canopy by winter storms, understory macroalgae and phytoplankton increased production in the Macrocystis control plot. This response was delayed for both groups, with phytoplankton production increasing in spring and understory increasing later during summer. The longer delay for understory macroalgae was likely due to restrictions in the timing of macroalgal recruitment and their slower growth rates compared with phytoplankton and with increased competition for light resulting from greater light absorption by the spring phytoplankton bloom. Surprisingly, total ecosystem production that included NPP by Macrocystis, phytoplankton, and understory algae did not differ between the Macrocystis control and removal plots for much of the study. NPP by understory algae, which comprised the bulk of the ecosystem NPP in the Macrocystis removal plot, can compensate to varying degrees for the loss of Macrocystis production following its removal by winter storms.

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Dissolved organic matter release in a Posidonia oceanica meadow

Cited by 94 publications

References 56 publications

Temperature and phosphorus regulating carbon flux through bacteria in a coastal marine system

Temperature and phosphorus regulating carbon flux through bacteria in a coastal marine system

Reduced carbon sequestration in a Mediterranean seagrass (Posidonia oceanica) ecosystem impacted by fish farming

Partitioning of primary production among giant kelp (Macrocystis pyrifera), understory macroalgae, and phytoplankton on a temperate reef

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