The interplay of nutrients, dissolved inorganic carbon and algae in determining macrophyte occurrences in rivers

Kaijser, Willem; Lorenz, Armin W.; Birk, Sebastian; Hering, Daniel

doi:10.1016/j.scitotenv.2021.146728

Cited by 17 publications

(9 citation statements)

References 36 publications

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“…Hence, looking at composition of macrophytes assemblages over large spatial scales, DIC related variables (e.g. CO 2 , HCO 3 − , GH, KH; all absent in this dataset) can lead to clearly observable difference (Iversen et al, 2019;Kaijser et al, 2021) and correlation (Demars et al, 2012). The input of nutrients might positively relate to the depletion of CO 2 and an increase of HCO 3 − by increasing the biomass of primary producers and altering biogeochemical pathways; in such a case, the relation of macrophyte assemblages to surface water nutrients is obvious, but might not be causal (Demars et al, 2012;Kaijser et al, 2021).…”

Section: Discussionmentioning

confidence: 95%

“…At a pH of 8.4 all carbonic acid (H 2 CO 3 ) has been transferred to bicarbonate (HCO 3 − ), whilst CO 2 concentration is low. This restricts the carbon source for species, which are only able to utilize CO 2 (Maberly et al, 2015;Svitok et al, 2016;Kaijser et al, 2021). On the contrary, species such as C. demersum, E. nuttallii and M. spicatum can utilize HCO 3 − .…”

Section: Discussionmentioning

confidence: 99%

“…In lakes, increased surface water nutrients shift macrophyte assemblages from meadow forming species (isoetids or Characeae) to canopy forming species (Myriophyllum spicatum L. or Ceratophyllum demersum L.) and eventually to the dominance of phytoplankton (van Zuidam & Peeters, 2013;Verhofstad et al, 2017;Poikane et al, 2018). Rivers also suffer from excessive nutrient inputs that modify macrophyte assemblages through competition with algae and a multitude of indirect pathways (Hilton et al, 2006;Novak & Chambers, 2014;Kaijser et al, 2021). This is also reflected by the development of a multitude of trophic indices (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Reach hydromorphology: a crucial environmental variable for the occurrence of riverine macrophytes

2022

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Management measures targeting riverine macrophyte species often address dissolved nitrogen and phosphorus compounds. With recent reductions of nutrient pollution, effects of other variables have become more apparent. This study aims to shed light on the hierarchy of variables determining riverine macrophyte distribution, covering both surface water nutrients and a range of other variables, in a Central European landscape. We used a dataset of 1,371 monitoring samples to predict the presence and absence of 30 common macrophyte species with multiple random forest models. Besides surface water chemical variables (P-PO4, TN and pH), five reach hydromorphological variables (substrate, flow velocity, shading, width and depth) and a variable related to river size (distance from the river source) were use as predictors. The most important variables for the prediction of the species’ presence and absence were substrate, distance from the river source and flow velocity. Additionally, P-PO4 and shade were also important, whilst TN, pH, width and depth played only a minor role. River hydromorphology was more important than surface water chemistry for the occurrences of individual riverine macrophyte species, in particular under less extreme eutrophic conditions. Species occurrences were related to multiple interacting variables, amongst which hydromorphology often prevailed. Presence/absence of species and composition of assemblages cannot be attributed to surface water nutrients alone, even when considering river typologies. Therefore, the results support the conjecture that a broader approach considering a range of stressors is necessary to design restoration measures for management and enhancement of macrophyte diversity.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reach hydromorphology: a crucial environmental variable for the occurrence of riverine macrophytes

2022

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“…This is probably related to the low number of observations for these species in our dataset, not representing their real distribution. It is yet to be noted that various authors challenged the role of TP as explanatory factor for macrophyte distribution due to absence of a direct known mechanistic link and spurious correlations [ 60 – 62 ].…”

Section: Discussionmentioning

confidence: 99%

Environmental ranges discriminating between macrophytes groups in European rivers

2022

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Riverine macrophytes form distinct species groups. Their occurrence is determined by environmental gradients, e.g. in terms of physico-chemistry and hydromorphology. However, the ranges of environmental variables discriminating between species groups (“discriminatory ranges”) have rarely been quantified and mainly been based on expert judgement, thus limiting options for predicting and assessing ecosystem characteristics. We used a pan-European dataset of riverine macrophyte surveys obtained from 22 countries including data on total phosphorus, nitrate, alkalinity, flow velocity, depth, width and substrate type. Four macrophyte species groups were identified by cluster analysis based on species’ co-occurrences. These comprised Group 1) mosses, such as Amblystegium fluviatile and Fontinalis antipyretica, Group 2) shorter and pioneer species such as Callitriche spp., Group 3) emergent and floating species such as Sagittaria sagittifolia and Lemna spp., and Group 4) eutraphent species such as Myriophyllum spicatum and Stuckenia pectinata. With Random Forest models, the ranges of environmental variables discriminating between these groups were estimated as follows: 100–150 μg L-1 total phosphorus, 0.5–20 mg L-1 nitrate, 1–2 meq L-1 alkalinity, 0.05–0.70 m s-1 flow velocity, 0.3–1.0 m depth and 20–80 m width. Mosses were strongly related to coarse substrate, while vascular plants were related to finer sediment. The four macrophyte groups and the discriminatory ranges of environmental variables fit well with those described in literature, but have now for the first time been quantitatively approximated with a large dataset, suggesting generalizable patterns applicable at regional and local scales.

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“…Thus, it is an ideal area for studying C-P interactions. DOC entering coastal water may affect P cycling by altering dissolved oxygen (DO) and microbial activities (Kaijser et al, 2021). For example, the decomposition of organic matter (OM; rich in C) is an oxygen-consuming process that creates low DO conditions, which could potentially favor sediment P release (Li et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Dissolved Organic Carbon Loading Stimulates Sediment Phosphorus Mobilization and Release: Preliminary Evidence From Xiangshan Port, East China Sea

Dong

Wang

et al. 2022

Front. Environ. Sci.

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Increasing concentrations of dissolved organic carbon (DOC) have been observed in coastal ecosystems worldwide over the past decade, and tight coupling of the carbon (C) and phosphorus (P) biogeochemical cycle has been recognized in aquatic ecosystems. However, there is still no consensus regarding the potential effects of DOC loading on sediment P release. In a 2-month mesocosm experiment, we tested the effects of DOC enrichment on sediment P release in six glass aquariums. Two treatments were set: Control (without sodium acetate (Na(CH3COO)) addition) and Na(CH3COO) addition (equivalent to 5 mg C L−1). The results showed the following: 1) DOC loading stimulated sediment P mobilization and release, as indicated by increases in the labile P recorded for 7-cm-deep sediment using diffusive gradients in thin films, the flux of P across the sediment–water interface, and the total P concentrations in the overlying water; and 2) stimulated alkaline phosphatase activity, increased P-solubilizing bacteria proportion, and decreased dissolved oxygen concentration were likely the primary mechanisms behind the DOC-stimulated sediment P mobilization and release. These results provide insight into the promotion of sediment P release induced by C addition. Further studies investigating the quantitative relationships between DOC loadings and P release are needed to fully elucidate the coupled roles of C and P, especially those based on large-scale field investigations with broader C forms and loadings.

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The interplay of nutrients, dissolved inorganic carbon and algae in determining macrophyte occurrences in rivers

Cited by 17 publications

References 36 publications

Reach hydromorphology: a crucial environmental variable for the occurrence of riverine macrophytes

Reach hydromorphology: a crucial environmental variable for the occurrence of riverine macrophytes

Environmental ranges discriminating between macrophytes groups in European rivers

Dissolved Organic Carbon Loading Stimulates Sediment Phosphorus Mobilization and Release: Preliminary Evidence From Xiangshan Port, East China Sea

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