Dynamics of the 1990 winter/spring bloom in Chesapeake Bay

Abstract

The winterkpring bloom of 1990 in Chesapeake Bay. USA, was prolonged and well developed, relative to other recent years, along the axis of the Bay. However, the bloom did not occur uniformly along the axis of the Bay, but rather developed and dissipated at different times in different regions of the Bay. The peak of the bloom progressed northward and was observed in late March in South Bay, early April in Mid Bay, and not until mid May in North Bay. We measured biomass and nutrient concentrations and the rates of carbon, nitrogen, phosphorus, and silicon utilization during the development and dissipation of the bloom, and compared ratios of these rates to the elemental ratios of the incoming nutrients and the resulting particulate material. In North Bay, bloom development was probably delayed due to light limitation of carbon uptake. Nitrogen was delivered and utilized in excess of stoichiometric proportions in the northern part of the Bay, eventually leading to phosphorus and/or silicon limitation. In the mid portion of the Bay, the mean stoichiometric proportions of the particulate nutrients were similar to Redfield proportions, but ratios of uptake of nitrogen and phosphorus exceeded Redfield proportions by more than 20-fold, reflecting both the high uptake rates of nitrogen and low uptake rates of phosphorus in that region. However, only at the peak of the bloom in mid April did transient phosphorus limitation of growth occur at Mid Bay. In contrast, ratios of nitrogen to phosphorus uptake rates in South Bay were considerably below Redfield proportions, primarily due to the low availability and low uptake rates of nitrogen. Concentrations of Si(OH), in South Bay were also extremely low through the bloom period, and thus Si(OH), and nitrogen, as well as pod3-, limited growth there. In addition, temperature appeared to play a key role in the collapse of the diatom assemblage in mid May. During the early stages of the bloom in South Bay, No3-+ NOzcontributed >60% of the total nitrogen utilized, but by the end of the spring bloom period in May, over 50% of the nitrogen uthzed was urea alone. These data underscore the need to understand how freshwater flow, ambient nutrient concentrations, temperature, and light dlffer along the axis of the Bay to understand the differential timing and magnitude of bloom development in different regions of the Bay.

Phytoplankton variation and its relationship with the environment in Xiangxi Bay in spring after damming of the Three-Gorges, China

“…The algae biomass in Xiangxi Bay was often determined by the nitrogen concentration. Nitrate was used before ammonium when diatoms dominated the phytoplankton community (Glibert et al 1982(Glibert et al , 1995Boyer et al 1994). In the present study, this phenomenon also occurred when diatoms or dinoflagellates bloom occurred.…”

Dissolved and particulate organic matter source-age characterization in the upper and lower Chesapeake Bay: A combined isotope and biochemical approach

“…Algal biomarkers such as C 16 and C 20 fatty acids (16:1v7, 16:2, 16:3, and 20:5v3) and C 28 D 5,22 and C 28 D 5,24(28) sterols (Canuel and Martens 1993;Volkman et al 1998 and references therein) were most abundant in the low-flow POM sample from SQR (Tables 3 and 4), suggesting that riverine sources of algal material may assume greater importance during low-flow regimes, with diatoms likely the predominant group (Table 4). Although diatoms generally dominate during spring phytoplankton blooms in the bay, a shift from diatoms to cyanobacteria and microflagellates occurs as the season progresses (Glibert et al 1995). Other biomarkers generally attributed to phytoplankton, bacteria, and cyanobacteria such as 16:1v7 and 18:1v9 (Table 3), and to crustacean zooplankton such as cholesterol (Table 4), were also found in all bay UDOM and POM samples.…”

Late spring phytoplankton bloom in the Lower St. Lawrence Estuary:the flushing hypothesis revisited

“…(Boyer et al 1993), the James River Estuary in Virginia (Moon 1990) or in the Lower Hudson Estuary (Malone et al 1980). In addition, the differential timing of the General implications spring bloom between the lower, medium and upper Chesapeake Bay reported by Glibert et al (1995) may…”

“…the whole estuary and gulf System (Levasseur et al Malone et al 1980, Legendre et al 1982, Harding 1984, Thernault & Levasseur 1985. The reasoning of 1994, Glibert et al 1995), would mask the effect of Levasseur et al (1984) was based on the Sverdrupflushing on phytoplankton dynamics in shallow StratiRiley critical depth model but it also appears from fied estuaries.…”