Benthic primary production and nutrient cycling in sediments with benthic microalgae and transient accumulation of macroalgae

Dalsgaard, Tage

doi:10.4319/lo.2003.48.6.2138

Cited by 93 publications

(89 citation statements)

References 49 publications

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“…In these vegetated sediment systems, benthic microalgae are an important food source for crustacean and gastropod herbivores, which in turn are eaten by fish and crustaceans (52). Through the production of oxygen via photosynthesis, microphytobenthos also "indirectly" control key biogeochemical processes in the sediment (53,54) and, in theory, could counteract effects of expected global warming by sustaining net benthic autotrophy (46).…”

Section: Methodsmentioning

confidence: 99%

Consumers mediate the effects of experimental ocean acidification and warming on primary producers

Alsterberg

Eklöf

Gamfeldt

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

145

132

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It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e. g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities.food web | global warming | herbivory | species interaction | top-down

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Section: Methodsmentioning

confidence: 99%

Consumers mediate the effects of experimental ocean acidification and warming on primary producers

Alsterberg

Eklöf

Gamfeldt

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

145

132

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“…Nitrification rates were calculated by the sum of NO 3 -efflux and p 14 n, assuming absence of benthic microalgae (Rysgaard et al 2004). Ammonification has to be considered as a potential ammonification rate and was calculated dividing the TOU by the C/N ratio, assuming a CO 2 /O 2 ratio of 1.2 (Dalsgaard 2003). Denitrification efficiency (DE), sensu Eyre and Ferguson (2009), was calculated as the ratio between the DIN flux and the N 2 production via denitrification/anammox.…”

Section: Laboratory Analysis and Calculationsmentioning

confidence: 99%

“…4). This fraction could have been retained by adsorption, assimilated in the sediment by bacteria, or could have been lost from the sediment in the form of DON (Dalsgaard 2003). NH 4…”

Section: N Transformation Pathways In Himmerfjärdenmentioning

confidence: 99%

Seasonal oxygen, nitrogen and phosphorus benthic cycling along an impacted Baltic Sea estuary: regulation and spatial patterns

et al. 2014

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The regulatory roles of temperature, eutrophication and oxygen availability on benthic nitrogen (N) cycling and the stoichiometry of regenerated nitrogen and phosphorus (P) were explored along a Baltic Sea estuary affected by treated sewage discharge. Rates of sediment denitrification, anammox, dissimilatory nitrate reduction to ammonium (DNRA), nutrient exchange, oxygen (O 2 ) uptake and penetration were measured seasonally. Sediments not affected by the nutrient plume released by the sewage treatment plant (STP) showed a strong seasonality in rates of O 2 uptake and coupled nitrification-denitrification, with anammox never accounting for more than 20 % of the total dinitrogen (N 2 ) production. N cycling in sediments close to the STP was highly dependent on oxygen availability, which masked temperaturerelated effects. These sediments switched from low N loss and high ammonium (NH 4 ? ) efflux under hypoxic conditions in the fall, to a major N loss system in the winter when the sediment surface was oxidized. In the fall DNRA outcompeted denitrification as the main nitrate (NO 3 -) reduction pathway, resulting in N recycling and potential spreading of eutrophication. A comparison with historical records of nutrient discharge and denitrification indicated that the total N loss in the estuary has been tightly coupled to the total amount of nutrient discharge from the STP. Changes in dissolved inorganic nitrogen (DIN) released from the STP agreed well with variations in sedimentary N 2 removal. This indicates that denitrification and anammox efficiently counterbalance N loading in the estuary across the range of historical and present-day anthropogenic nutrient discharge. Overall low N/P ratios of the regenerated nutrient fluxes impose strong N limitation for the pelagic system and generate a high potential for nuisance cyanobacterial blooms.

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“…In general, substrate limitation is not considered rate limiting in coastal shallow water sediments, as a net flux of nutrients and DOC from the sediment to the water column is typical (Dalsgaard 2003). However, due to the tight spatial and temporal coupling between production and consumption of organic matter (e.g.…”

Section: Heterotroph Versus Phototroph Temperature Responsementioning

confidence: 99%

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

Hancke¹,

Glud²

2004

Aquat. Microb. Ecol.

118

113

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Short-term temperature effects on respiration and photosynthesis were investigated in intact diatom-dominated benthic communities, collected at 2 temperate and 1 high-arctic subtidal sites. Areal rates of total (TOE) and diffusive (DOE) O 2 exchange were determined from O 2 -microsensor measurements in intact sediment cores in the temperature range from 0 to 24°C in darkness and at 140 µmol photons m -2 s -1 . In darkness, the O 2 consumption increased exponentially with increasing temperature for both TOE and DOE, and no optimum temperature was observed within the applied temperature range. Q 10 was calculated from the linear slope in Arrhenius plots and ranged between 1.7 and 3.3 at the respective sites. The volume-specific rate (R dark,vol ) solely representing the biological temperature response was somewhat stronger, with Q 10 values of 2.6 to 5.2. The Q 10 values were overall not correlated to the in situ water temperature or geographical position. Accordingly, no difference in the temperature acclimation or adaptation strategy of the microbial community was observed. Slurred oxic sediment samples showed a Q 10 of 1.7 and were, hence, lower than estimates based on intact sediment core measurements. This can be ascribed to changes in physical and biological controls during resuspension. Gross photosynthesis was measured with the light-dark shift method at the 2 temperate sites. Both areal (P gross ) and volumetric (P gross,vol ) rates increased with temperature to an optimum temperature at 12 and 15°C, with a Q 10 for P gross of 2.2 and 2.6 for the 2 sites, respectively. The gross photosynthesis response could be categorised as psychrotrophic for both sites and no temperature adaptation was observed between the 2 sites. Our measurements document that temperature stimulates heterotrophic activity more than gross photosynthesis, and that the benthic communities gradually become heterotrophic with increasing temperature. This has implications for C-cycling in shallow water communities experiencing seasonal and diel temperature fluctuations.

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Benthic primary production and nutrient cycling in sediments with benthic microalgae and transient accumulation of macroalgae

Cited by 93 publications

References 49 publications

Consumers mediate the effects of experimental ocean acidification and warming on primary producers

Consumers mediate the effects of experimental ocean acidification and warming on primary producers

Seasonal oxygen, nitrogen and phosphorus benthic cycling along an impacted Baltic Sea estuary: regulation and spatial patterns

Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

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