Organic matter processing through an estuarine system: Evidence from stable isotopes (δ13C and δ15N) and molecular (lignin phenols) signatures

Stable carbon (C) and nitrogen (N) isotopes in plants are important indicators of plant water use efficiency and N acquisition strategies. While often regarded as being under environmental control, there is growing evidence that evolutionary history may also shape variation in stable isotope ratios (δ13C and δ15N) among plant species. Here we examined patterns of foliar δ13C and δ15N in alpine tundra for 59 species in 20 plant families. To assess the importance of environmental controls and evolutionary history, we examined if average δ13C and δ15N predictably differed among habitat types, if individual species exhibited intraspecific trait variation (ITV) in δ13C and δ15N, and if there were a significant phylogenetic signal in δ13C and δ15N. We found that variation among habitat types in both δ13C and δ15N mirrored well-known patterns of water and nitrogen limitation. Conversely, we also found that 40% of species exhibited no ITV in δ13C and 35% of species exhibited no ITV in δ15N, suggesting that some species are under stronger evolutionary control. However, we only found a modest signal of phylogenetic conservatism in δ13C and no phylogenetic signal in δ15N suggesting that shared ancestry is a weaker driver of tundra wide variation in stable isotopes. Together, our results suggest that both evolutionary history and local environmental conditions play a role in determining variation in δ13C and δ15N and that considering both factors can help with interpreting isotope patterns in nature and with predicting which species may be able to respond to rapidly changing environmental conditions.

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Stable isotopes (δ13C and δ15N) in black coral as new proxies for environmental record

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2021.112007 ◽

2021 ◽

Vol 164 ◽

pp. 112007

Author(s):

Dan Wu ◽

Fenfen Zhang ◽

Xiaodi Zhang ◽

Xiubao Li ◽

Hui Huang ◽

...

Keyword(s):

Stable Isotopes ◽

Δ13c And Δ15n ◽

Black Coral

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Carbon and nitrogen stable isotopes of copepods in a tidal estuarine system in Maryland, USA

Regional Studies in Marine Science ◽

10.1016/j.rsma.2021.101620 ◽

2021 ◽

Vol 42 ◽

pp. 101620

Author(s):

Blessing O. Edje ◽

Paulinus Chigbu

Keyword(s):

Stable Isotopes ◽

Estuarine System ◽

Nitrogen Stable Isotopes ◽

Carbon And Nitrogen ◽

Tidal Estuarine System

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Nutrient behavior in a highly-eutrophicated tropical estuarine system

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x3416 ◽

2016 ◽

Vol 28 (0) ◽

Cited By ~ 5

Author(s):

Nilva Brandini ◽

◽

Ana Paula de Castro Rodrigues ◽

Ilene Matanó Abreu ◽

Luiz Carlos Cotovicz Junior ◽

...

Keyword(s):

Organic Matter ◽

Chlorophyll A ◽

River Mouth ◽

Nutrient Concentrations ◽

Phytoplankton Production ◽

Small Scale ◽

Estuarine System ◽

Temperature Conductivity ◽

Se Brazil ◽

Iguaçu River

Abstract Aim: There are few studies dealing with the biogeochemical processes occurring in small estuaries receiving high sewage loading in tropical regions. The aim of this investigation was to characterize the biogeochemical behavior of nutrients in superficial waters collected at the Iguaçu estuarine system, during specific conditions (neap tide), located at the inner sector of a heavily eutrophicated embayment (Guanabara Bay, SE Brazil). Methods Physical and chemical variables were measured in situ (pH, temperature, conductivity, salinity, total dissolved solids, transparency, dissolved oxygen), whereas suspended particulate matter, chlorophyll a, phaepigments and nutrients (carbon, nitrogen and phosphorus forms) were measured in laboratory across the mesohaline estuarine gradient. Results The Iguaçu River mouth is in a high stage of eutrophication, considering nutrient concentrations, chlorophyll a and transparency of water column. Results indicate a transition from heterotrophic conditions to autotrophic conditions, since the nutrients concentrations showed a decreasing pattern along the saline gradient, while the chlorophyll an increased over the transects. The pH values and chlorophyll : phaeopigments ratios are significantly related to the amount and quality of organic matter contents, especially at transects under strong marine influence. More than 95% of the dissolved and total nitrogen concentrations are represented by NH4+ contributions, which are related to the ammonification of organic matter contents in this region, indicating the existence of untreated sewage loads in this area. Conclusion In this study, the Iguaçu River seemed to contribute with high inputs of nutrients that support important phytoplankton production at the inner regions of the bay related to the CO2 sink and autotrophic metabolism, showing the importance of verifying the biogeochemical behaviors of nutrients in estuarine areas, even in small scale.

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Linking patterns of freshwater discharge and sources of organic matter within the Río de la Plata estuary and adjacent marshes

Marine and Freshwater Research ◽

10.1071/mf16286 ◽

2017 ◽

Vol 68 (9) ◽

pp. 1704 ◽

Cited By ~ 5

Author(s):

Leandro Bergamino ◽

Mark Schuerch ◽

Adriana Tudurí ◽

Silvina Carretero ◽

Felipe García-Rodríguez

Keyword(s):

Organic Matter ◽

Surface Sediments ◽

Sediment Cores ◽

Freshwater Discharge ◽

C3 Plants ◽

Estuarine System ◽

Rio De La Plata ◽

Río De La Plata ◽

La Plata ◽

Matter Transport

We investigated carbon isotopic ratios (δ13C) v. carbon to nitrogen (C : N) ratios for surface sediments throughout a large estuarine system (Río de la Plata, RdlP), combined with sediment cores from adjacent marshes to infer main carbon sources. We also evaluated the influence of the El Niño–Southern Oscillation (ENSO) and associated high freshwater-discharge events on the organic-matter transport within the estuary. The isotopic pattern in surface sediments of the RdlP showed the upper reaches to be influenced by riverine particulate matter (δ13C range: –24 to –26‰). Similarly, in the sediment cores from marshes of the upper reaches, δ13C values decreased from –24‰ in ancient sediments to –28‰ in recent sediments, reflecting an increased contribution of organic matter from land, including C3 plants and freshwater phytoplankton, during the past 50 years. However, the lower reaches represent a depositional environment of marine algae (δ13C range: –21 to –23‰), with no influence of detritus from adjacent marshes, indicating minor erosion of the marshes in the lower reaches operating as carbon-sink habitats. Our isotopic analysis showed that the transport and deposition of terrigenous organic matter within the RdlP and adjacent marsh habitat appear to be both temporally and spatially linked to hydrology patterns.

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