Evaluating phytoplankton dynamics in the Newport River estuary (North Carolina, USA) by HPLC-derived pigment profiles

Abstract

The composition and dynamics of phytoplankton assemblages during the spring bloom in a shallow, coastal-plain estuary were characterized by high-performance liquid chromatography (HPLC)-derived pigment profiles. From mid-February through the first week in June 1991, samples were collected twice weekly at 2 sites within the Newport River estuary, North Carolina, USA. Pigment profiles, reflecting phytoplankton assemblages dominated by diatoms, dinoflagellates, prymnesiophytes, cryptophytes, and chlorophytes, were compared to phytoplankton cell counts. There were significant ( p 5 0.0005, r 2 = 0.49 to 0 63) relationsh~ps between the taxon-specific pigment concentrations and the taxon-specific cell numbers HPLC-determined chlorophyll (chl) a biomass corresponded wlth the sum of the taxon-spec~fic chl a biomass ( p S 0.001, r2 = 0.95). Each taxon-specific biomass was calculated based on chl a:accessory pigment ratlos determined by regression analyses. Chl a biomass was also measured fluorometr~cally and compared with the HPLC results. Fluorometric analysis underestimated bio~nass when prymnesiophytes, cryptophytes, and chlorophytes dominated the phytoplankton. Despite the inherent environmental vanability of the estuarine sampling location, HPLC-derived pigment profiles did provide division-level phylogenetic assessment of large, short-term changes in the phytoplankton composition and detected assemblage responses to event-scale perturbation effects (e.g. precipitation, wind). These results demonstrate that even in highly variable environments HPLCbased pigment analysis is a valuable tool, providing complementary information to the traditional methodology of cell counting.

Seasonal niche strategy of the bloom-forming dinoflagellate Heterocapsa triquetra

“…8). This increase in diatom biomass was associated with the rapid increase in water temperatures that occurred in late March and appears to be a regular occurrence in North Carolina estuaries (Tester et al 1995. The beginning of the annual increase in copepod abundances also coincides with this rapid increase in ambient temperatures (Fig.…”

“…H. triquetra exploits these conditions and out-competes co-occurring species, even though some of the prevailing conditions, such as temperature and light, are suboptimal for phytoplankton growth (Hobbie 1971, Hobbie et al 1972, Campbell 1973, Kuenzler et al 1979, Lapennas 1980, Palumbo 1982, Pfaender & Paerl 1984, Stanley & Daniel 1985, Litaker et al 1993, Tester et al 1995. How H. triquetra exploits and responds to the various environmental conditions is discussed below.…”

“…Excess water was removed from the filters by blotting before freezing the samples at -80°C. The HPLC pigment profiles for each sample were determined using the methods described in Tester et al (1995) and Pinckney et al (1998).…”

“…Often this decline occurred by mid-to late February, with blooms seldom lasting beyond mid-March or the first week in April as water temperatures reached 17 to 19°C (Hobbie 1971, Hobbie et al 1972, Carpenter 1973, Kuenzler et al 1979, Tester et al 1995. Though the general period when the blooms declined was fairly similar, the causes appeared variable.…”

Detection of harmful algal blooms using photopigments and absorption signatures: A case study of the Florida red tide dinoflagellate, Gymnodinium breve

“…Demers ct al. 1991;Johnsen and Sakshaug 1993;Kroon et al 1993;Johnsen et al 1994a,b;Kroon 1994;Millie et al 1995a;Tester et al 1995). These analyses are complementary to microscopic analyses and are well suited for assessment programs because they facilitate rapid processing of large numbers of samples acquired over diverse spatial and temporal scales.…”