Regulation of algal structure and function by nutrients and grazing in a boreal wetland

Rober, Allison R.; Wyatt, Kevin H.; Stevenson, R. Jan

doi:10.1899/10-166r.1

Cited by 24 publications

(36 citation statements)

References 47 publications

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“…Crayfish activity enhanced this process, but facilitated the growth of filamentous algae rather than phytoplankton. Furthermore, according to Rober et al (2011), filamentous algae development is also enhanced by invertebrate grazer reduction. A similar reduction occurred in our experiment (Fig.…”

Section: Discussionmentioning

confidence: 99%

Temporary pond ecosystem functioning shifts mediated by the exotic red swamp crayfish (Procambarus clarkii): a mesocosm study

2015

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International audienceTemporary ponds, acknowledged for their conservation value, are colonized by the invasive crayfish Procambarus clarkii. We have tested the consequences of this colonization for the ecosystem under two contrasted scenarios: one single individual arrival or three individuals arrival. We recreated the temporary pond ecosystem in 1 m(2) tanks to investigate the impact of the two crayfish densities. We studied the macrophyte community composition and abundance, chlorophyll a and total suspended solids concentrations, and the diversity and functional composition of micro-crustacean and macro-invertebrate communities. We observed a reduction of macrophyte biomass in experimental crayfish mesocosms in comparison with control tanks, nearly 80 and 40% less in 3 and 1 crayfish/m(2) tanks, respectively. The macrophyte community shifted, followed by a filamentous algae development, an increase of bare sediment and turbidity in crayfish tanks. The macro-invertebrate community suffered a richness loss of 28 and 22%, in 3 and 1 crayfish/m(2) tanks, respectively. Functionally, macro-invertebrate diversity reduction most strongly affected the grazer, detritivore and predator trophic groups. Microcrustaceans seemed not to be affected by the introduction of the crayfish. The introduction of the crayfish greatly altered the ecosystem structure and subsequently the ecosystem functioning

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Section: Discussionmentioning

confidence: 99%

Temporary pond ecosystem functioning shifts mediated by the exotic red swamp crayfish (Procambarus clarkii): a mesocosm study

2015

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“…Our hypothesis that nutrient drawdown was due to algal sequestration is supported by the increase in algal productivity and nutrient content immediately following the spike in nutrient levels, and then by the rapid reduction in water-column nutrient levels following the increase in algal productivity. The ability of algae to rapidly respond to and assimilate nutrients from the water column has been well documented in wetlands receiving external nutrient inputs (Richardson 2010; Rober et al 2011). In the Florida Everglades, algae can sequester P rapidly (Noe et al 2001), making it almost undetectable in the water column only a few meters from the source (Gaiser et al 2004).…”

Section: Discussionmentioning

confidence: 99%

Contributions of algae to GPP and DOC production in an Alaskan fen: effects of historical water table manipulations on ecosystem responses to a natural flood

et al. 2011

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The role of algae in the metabolism of northern peatlands is largely unknown, as is how algae will respond to the rapid climate change being experienced in this region. In this study, we examined patterns in algal productivity, nutrients, and dissolved organic carbon (DOC) during an uncharacteristically wet summer in an Alaskan rich fen. Our sampling was conducted in three large-scale experimental plots where water table position had been manipulated (including both drying and wetting plots and a control) for the previous 4 years. This study allowed us to explore how much ecosystem memory of the antecedent water table manipulations governed algal responses to natural flooding. Despite no differences in water table position between the manipulated plots at the time of sampling, algal primary productivity was consistently higher in the lowered water table plot compared to the control or raised water table plots. In all plots, algal productivity peaked immediately following seasonal maxima in nutrient concentrations. We found a positive relationship between algal productivity and water-column DOC concentrations (r (2) = 0.85, P < 0.001). Using these data, we estimate that algae released approximately 19% of fixed carbon into the water column. Algal exudates were extremely labile in biodegradability assays, decreasing by more than 55% within the first 24 h of incubation. We suggest that algae can be an important component of the photosynthetic community in boreal peatlands and may become increasingly important for energy flow in a more variable climate with more intense droughts and flooding.

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“…Disturbance associated with nutrient inputs often lead to unintended consequences in aquatic ecosystems, including increased abundance of benthic algae (Raven and Taylor 2003, Worm and Lotze 2006, Rober et al 2011. Few places exist where this fact is more apparent than in the lower Laurentian Great Lakes where increased water clarity and nutrient availability associated with increases in the abundance of invasive dreissenid mussels have resulted in greater benthic algal biomass along the shoreline (e.g., Malkin et al 2010).…”

Section: Implications Of Exudate Release For the Laurentian Great Lakmentioning

confidence: 99%

Effects of nutrient limitation on the release and use of dissolved organic carbon from benthic algae in Lake Michigan

et al. 2014

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Compared to phytoplankton, relatively little information exists about the importance of benthic algae as a source of dissolved organic C (DOC) in lakes. We enriched outdoor tanks with N and P in a full factorial design (unenriched, +N, +P, N+P) to evaluate effects of nutrients on the release, composition, and decomposition of DOC from Cladophora glomerata (L.) Kütz. in Lake Michigan. After 10 d of enrichment, biomass-specific rates of gross primary productivity (GPP) were significantly greater in the N+P treatment than in the +N or +P treatments. The fraction of fixed C released as DOC was ∼37% of GPP in the N+P treatment, which was similar to material collected from the lake (initial samples). Biomass-specific rates of DOC release did not vary significantly with treatment, whereas GPP declined in the nutrient-limited treatments (+N, +P, and unenriched). Consequently, DOC release represented a higher percentage of GPP (>100%) under severe nutrient limitation. Specific ultraviolet (UV) absorbance, an indicator of aromatic compounds, indicated that DOC from material grown in the N+P treatment (DOC N+P ) was more labile than DOC from material grown in the +N treatment (DOC +N ). Both DOC N+P and DOC +N supported an exponential increase in bacterial density during a 19-d incubation, but DOC N+P was used more rapidly and supported higher bacterial density than DOC +N . Cladophora has become a major contributor to primary production in the shallow nearshore areas of the lower Laurentian Great Lakes, and our data suggest that ≥⅓ of this productivity is available for the benthic microbial loop as DOC. The amount of DOC released remains relatively constant as nutrient limitation reduces productivity, but the nutrient status of the alga affects the quality of DOC as a substrate for heterotrophic bacteria.

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Regulation of algal structure and function by nutrients and grazing in a boreal wetland

Cited by 24 publications

References 47 publications

Temporary pond ecosystem functioning shifts mediated by the exotic red swamp crayfish (Procambarus clarkii): a mesocosm study

Temporary pond ecosystem functioning shifts mediated by the exotic red swamp crayfish (Procambarus clarkii): a mesocosm study

Contributions of algae to GPP and DOC production in an Alaskan fen: effects of historical water table manipulations on ecosystem responses to a natural flood

Effects of nutrient limitation on the release and use of dissolved organic carbon from benthic algae in Lake Michigan

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