Phytoplankton photosynthesis, productivity, and species composition in a eutrophic estuary: comparison of bloom and non-bloom assemblages

Gallegos, CL

doi:10.3354/meps081257

Cited by 52 publications

(39 citation statements)

References 24 publications

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“…The model with plausible parameters (Table 4) reproduced the essential features of the bloom. A local minimum in the data that was not reproduced in the inodel occurred near 29 June, which is probably associated with a shift of community dominance from dinoflagellates to cryptomonads and other autotrophic microflagellates (Malone et al 1988, Gallegos 1992, or other loss processes (sedimentation, senescence) not incorporated in the model. Similarly, there was an ephemeral autumnal bloom which was present in only 1 sampling and was localized to segment 4 (Gallegos unpubl.).…”

Section: Resultsmentioning

confidence: 99%

Seasonal progression of factors limiting phytoplankton pigment biomass in the Rhode River estuary, Maryland (USA). II. Modeling N versus P limitation

Gallegos¹,

Jordan²

1997

Mar. Ecol. Prog. Ser.

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Pre\~iously reported experiments demonstrated that N addition enhanced phytoplankton growth rate more frequently and to a greater extent than did addition of P alone. Here w e develop a modcl of nutrient-limited net phytoplankton production for the Rhode River estuary, Maryland (USA). to determine the sensitivity of observed patterns to changes in the manner in which nutrients are delivered to the system The model successfully reproduced the seasonal pattern of phytoplankton chlorophyll variation for an average year, the relatlve timlng of P and N limitat~on, and the ~nterannual val-1-ability in the timing of the shift from P to N limitation. Manipulat~on of nutrient sources In the model suggested that the disappearance of N at the seaward boundary of the estuary is sufficient to produce the shift from P to N I~inltation. Raising the modeled N:P ratio of sediment nutrient release to a value greater than that of the phytoplankton biolnass caused CO-liinltation by both N and P in the sumnler, but no manipulations produced lim~tation solely by P in the summer. In the model, different computed indicators of nutrient limitation (i.e. ratios of available N:P, physiological ~ndicators of internal nutrient pools, and computed growth stimulation by nutrient additions) generally identified the same nutrient as limiting at a particular time. The model demonstrates how observed shifts in nutrient limitation result from changes In delivery of N and P from the watershed, from the sediment, and from incoming phytoplankton.

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Section: Resultsmentioning

confidence: 99%

Seasonal progression of factors limiting phytoplankton pigment biomass in the Rhode River estuary, Maryland (USA). II. Modeling N versus P limitation

Gallegos¹,

Jordan²

1997

Mar. Ecol. Prog. Ser.

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“…The majority of the samples were collected from the Rhode River, which is a turbid, eutrophic (Gallegos 1992) subestuary on the western shore of the Chesapeake Bay in Maryland. The primary sampling site (Sta.…”

Section: Methodsmentioning

confidence: 99%

“…However, a more detailed data set is needed to test this hypothesis. Previous studies in the Rhode River have documented brief (i.e., several day) phytoplankton blooms, which are induced by episodic nutrient enrichment (Gallegos 1992;Gallegos et al 1992), and short-term forcing of photosynthesis is probably a general feature of shallow estuarine environments (MacIntyre et al 2000).…”

Section: Comparison With Other Biological Weighting Functions-mentioning

confidence: 99%

“…A similar analysis based on the correlation of a det (340) and K d for PAR in the Rhode River indicates that changes in water transparency had less impact on the seasonal variation of PAR (Table 3). Seasonal variation of nutrient availability is well established for the Rhode River (Gallegos et al 1992;Jordan et al 1992). In particular, nitrate is usually abundant in the late fall through early spring but low the rest of the year (except for episodic watershed events).…”

Section: Seasonal Variation In Biological Weighting Functions-p-mentioning

confidence: 99%

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Ultraviolet radiation sensitivity of photosynthesis in phytoplankton from an estuarine environment

Banaszak

Neale

2001

Limnology & Oceanography

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We have studied temporal variation in the sensitivity of phytoplankton photosynthesis to inhibition by ultraviolet radiation (UV; 280-400 nm) using biological weighting functions (BWFs) that quantify the biological effect of different wavelengths of UV. Variations in irradiance-dependent BWFs were evaluated for natural phytoplankton assemblages from the Rhode River, a shallow subestuary of the Chesapeake Bay, Maryland, from October 1994 to July 1996. Phytoplankton assemblages were sensitive to UV throughout the year. Rhode River assemblages are inhibited more strongly in the UV-B (280-320 nm), particularly below 300 nm, but there is a significant influence well into the UV-A (320-400 nm). There was no inhibition of phytoplankton photosynthesis by photosynthetically available radiation (400-700 nm), but there was significant seasonal variation in the saturated rate of photosynthesis (P ) and in the light saturation parameter (E s ). There was little variation in seasonal average BWFs through the Ϫ2 ]) and in the spectral shape or relative effect of UV-B versus UV-A, which may be due to changes in species composition, light, temperature, and nutrient availability. Comparison of the most sensitive assemblage (spring) with the least sensitive assemblage (winter) indicates that these BWFs are close to the upper and lower bounds in sensitivity for irradiance-dependent BWFs from all natural and cultured phytoplankton populations. The average, absolute spectral weightings for inhibition of photosynthesis in assemblages from the Rhode River are similar to an average BWF for Antarctic assemblages.

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“…For counting, 1 to 10 ml were settled (minimum 4 h) and viewed at a magnification of 512ϫ under an inverted microscope (Gallegos 1992). Here we only report concentrations of the dominant bloom organism, P. minimum, as well as empty thecae of P. minimum as an indicator of increasing detritus toward the termination of the bloom (see Results).…”

Section: Optical Monitoringmentioning

confidence: 99%

Impact of the Spring 2000 phytoplankton bloom in Chesapeake Bay on optical properties and light penetration in the Rhode River, Maryland

Gallegos

Jordan

2002

Estuaries

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Accelerating eutrophication manifest as increasing frequency and magnitude of phytoplankton blooms threatens living resources in many estuaries. Effects of large blooms can be difficult to document because blooms are often unexpected and do not always coincide with scheduled sampling programs. Here we use continuously monitored salinity distributions and optical properties to study the spring bloom of the red tide dinoflagellate, Prorocentrum minimum, in the Rhode River, Maryland, a tributary embayment of upper Chesapeake Bay. Salinity distributions, together with weekly cruise measurements of nutrient concentrations, indicate that the bloom commenced with an influx of nitrate at the mouth due to the arrival of a freshet from the Susquehanna River. Arrival of this freshet at the mouth set up an unstable, inverse salinity gradient within the Rhode River. Continuously monitored absorption and scattering spectra indicated that increases in chlorophyll within the Rhode River initially were due to the influx of chlorophyll that had developed in the main stem of the bay. After the influx, much higher concentrations and steep spatial gradients developed within the Rhode River, subsequent to reduced mixing that accompanied re-establishment of a normal estuarine salinity gradient. We used the monitored absorption and scattering coefficients to determine the effect of the bloom on light attenuation coefficients in the Rhode River. The bloom resulted in a nearly three-fold increase in attenuation coefficient. Attenuation was dominated by chlorophyll in the early stages of the bloom and by detritus after the termination of the bloom. Although the bloom lasted only 20 d, the elevated attenuation coefficients due to the bloom exceeded values that would permit growth of submersed vascular plants for a period of about 45 d.

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Phytoplankton photosynthesis, productivity, and species composition in a eutrophic estuary: comparison of bloom and non-bloom assemblages

Cited by 52 publications

References 24 publications

Seasonal progression of factors limiting phytoplankton pigment biomass in the Rhode River estuary, Maryland (USA). II. Modeling N versus P limitation

Seasonal progression of factors limiting phytoplankton pigment biomass in the Rhode River estuary, Maryland (USA). II. Modeling N versus P limitation

Ultraviolet radiation sensitivity of photosynthesis in phytoplankton from an estuarine environment

Impact of the Spring 2000 phytoplankton bloom in Chesapeake Bay on optical properties and light penetration in the Rhode River, Maryland

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