Phytoplankton community dynamics in response to seawater intrusion in a tropical macrotidal river-estuary continuum

Sá, Ana Karoline D.S.; Feitosa, Fernando Antônio do Nascimento; Cutrim, Marco Valério Jansen; Flores‐Montes, Manuel; Costa, Denise dos Santos; Cavalcanti, Lisana Furtado

doi:10.1007/s10750-022-04851-7

Cited by 5 publications

(4 citation statements)

References 93 publications

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“…The mixing of freshwater and seawater resulted in large numbers of phytoplankton taxa (422) in QRE TFZ being transported from upstream river locations and downstream Hangzhou Bay, consistent with previous observations in other estuaries (Muylaert & Sabbe, 1999; Sá et al., 2022). Throughout the year, many freshwater, brackish‐water, coastal low‐salinity, euryhaline species and several offshore hyperhaline species (genera Neoceratium ) were observed.…”

Section: Discussionsupporting

confidence: 87%

“…This spatial difference in phytoplankton abundance matched the distribution of chlorophyll a in the lower reaches of QR (Lai et al, 2021;Zhang et al, 2021). Similar results were also found for other macrotidal estuaries, such as the Changjiang (Jiang et al, 2013), Youngsan (Sin et al, 2015) and Itapecuru river estuaries (Sá et al, 2022). The tidal bore and associated turbulence and sediment resuspension in QRE decreased significantly from the lower to the upper estuary (Xie & Pan, 2013), resulting in SPM increasing and SD decreasing from the upper to the lower TFZ (Figure 2).…”

Section: Environmental Drivers Of Phytoplankton Variationsupporting

confidence: 82%

“…Freshwater species were usually dominant in the low‐salinity (<0.5 PSU) upper estuary. Their abundances gradually decreased toward the lower estuary (Bharathi et al., 2022; Licursi et al., 2006; Muylaert et al., 2000), but some of them (particularly cyanobacteria) inhabited or extended into and accumulated in brackish (up to 5–10 PSU) waters and even highly saline (>15 PSU) lower estuary (Bharathi et al., 2022; Sá et al., 2022; Sellner et al., 1988). Coastal phytoplankton species also tolerate short term exposure to low salinity, regardless of the influence on photosynthesis and cell growth (Olli et al., 2019; Rijstenbil, 1988; Roshith et al., 2018).…”

Section: Discussionmentioning

confidence: 99%

“…These findings suggested that cyanobacteria variation in QRE TFZ was largely regulated by temperature, river flow and phosphorus. Several studies observed that cyanobacteria abundance and dominance increased in other rivers, TFZs and estuaries during periods of reduced river flow (Bormans et al, 2005;Bukaveckas et al, 2018;Sá et al, 2022;Valdes-Weaver et al, 2006). Li et al (2020) used a hydrodynamicecological model and found that high temperature and abundant nutrients and low river flow promoted cyanobacterial growth and bloom in QRE in 2004.…”

Section: Cyanobacteria Variation and Implications For Reducing The Ri...mentioning

confidence: 99%

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Physical Drivers of Monthly Variation in Phytoplankton Community in the Tidal Freshwater Zone of the Macrotidal Qiantang River Estuary, Eastern China: Implications for Reducing the Risk of Harmful Cyanobacterial Blooms

Jiang

Zhu

et al. 2023

JGR Oceans

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The Qiantang river estuary flows into Hangzhou Bay, on the East China Sea, and has one of the largest tidal bores worldwide. The tidal freshwater zone (TFZ) in this shallow macrotidal estuary is subjected to strong riverine and marine forcings. We investigated monthly variation of phytoplankton and environmental drivers in the upper and lower sections of TFZ during 2016. Large numbers of phytoplankton taxa (422) and genera (161) were identified. Diatoms were dominant in most months, but cyanobacteria abundance reached its greatest in warm months when runoff was low. Surprisingly, relatively high dominances of marine diatom species (e.g., Cyclotella stylorum, Skeletonema, and Thalassiosira) were observed in the TFZ with salinities usually <1 PSU. Microcystis contributed up to 50% to phytoplankton abundance in the upper TFZ in September, consistent with upstream bloom events. Abundances of phytoplankton and cyanobacteria were significantly negatively correlated with monthly runoff and sediment fluxes. Generalized additive models suggested that variation in phytoplankton abundance was largely explained by river flow, temperature and nutrients. Phytoplankton community composition varied significantly across different months and sections. Redundancy analysis indicated that temperature and flow rate explained more variation in phytoplankton community than other variables, but nutrients, Secchi depth and salinity also contributed significantly to the explained variation. Variance partitioning analysis confirmed that phytoplankton variation was largely regulated by physical variables rather than nutrients. These findings highlight the unexpectedly great phytoplankton species richness, dominance of marine diatoms, and physical drivers in the eutrophic macrotidal TFZ under strong tidal forcing.

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Section: Discussionsupporting

confidence: 87%