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The hydrography, water chemistry and plankton communities of Buzzards Bay, Massachusetts, USA, a temperate estuary (41-degrees-N), were studied over 45 cruises (10 October 1987 to 11 September 1990). Surface temperature varied from -2.0 to 27.26-degrees-C (n = 360), but because of shallow depth (mean = 10 m), strong wind and tidal mixing, the water...
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... were collected at all 8 stations sewage outfall exhibit substantial eutrophication on each of 45 cruises between 1 October 1987 and effects (Smayda 1989). Although information on 11 September 1990 (Table 1). All stations were specific, usually polluted, subsections of the bay con- sampled in a single day on each cruise. ...
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... These trends in the biofilm microbial community parallel that of the planktonic community in nearby waters. The abundance of heterotrophic bacteria in waters near Woods Hole was shown to increase rapidly in the late spring and summer months (Borkman & Turner 1993b), which could have been a signal, in part, to the dispersal of bacteria from biofilms. In addition, the abundance of their grazers also increased in lockstep (Borkman & Turner 1993b), which introduces the possibility that intensification in grazing rates during the summer could lead to greater mortality for biofilm microbes as well, thereby decreasing accumulation rates. ...
... The abundance of heterotrophic bacteria in waters near Woods Hole was shown to increase rapidly in the late spring and summer months (Borkman & Turner 1993b), which could have been a signal, in part, to the dispersal of bacteria from biofilms. In addition, the abundance of their grazers also increased in lockstep (Borkman & Turner 1993b), which introduces the possibility that intensification in grazing rates during the summer could lead to greater mortality for biofilm microbes as well, thereby decreasing accumulation rates. On the other hand, the eukaryotic phytoplankton community typically transitions from diatoms, which are known to contribute to microbial biofilms, to other classes of phytoplankton that might be less inclined toward settling (Turner et al. 2009); this could also lead to a decrease in accumulation rates. ...
The accumulation of microbial biofilms on ships' hulls negatively affects ship performance and efficiency while also playing a role in the establishment of even more detrimental hard-fouling communities. However, there is little quantitative information on how the accumulation rate of microbial biofilms is impacted by the balance of the rates of cell settlement, in situ production (ie growth), dispersal to surrounding waters and mortality induced by grazers. These rates were quantified on test panels coated with copper-based antifouling (AF) or polymer-based fouling-release (FR) coatings by using phospholipids as molecular proxies for microbial biomass. The results confirmed the accepted modes of efficacy of these two types of coatings. In a more extensive set of experiments with only the FR coatings, it was found that seasonally averaged cellular production rates were 1.5 ± 0.5 times greater than settlement and the dispersal rates were 2.7 ± 0.8 greater than grazing. The results of this study quantitatively describe the dynamic balance of processes leading to the accumulation of microbial biofilm on coatings designed for ships' hulls.
... The considerable variability may reflect increasing importance of other processes under conditions that supported higher chl a (White et al. 2006) or else that the weekly sampling period was less suitable at resolving bacteria dependence on presumed resources (phytoplankton) under bloom conditions . Bacteria in the Skidaway River estuary were also strongly correlated with water temperature (Table 3) as observed in Buzzards Bay (Turner and Borkman 1993), Narragansett Bay (Staroscik and Smith 2004 ), and Chesapeake Bay (Shiah and Ducklow 1994). At the community level, bacteria are often as suitable as photosynthetic nanoplankton as prey for heterotrophic nanoplankton . ...
The Skidaway River estuary, GA (USA), a tidally dominated subtropical system surrounded by exten-sive Spartina salt marshes, is experiencing steady increases in nutrients, chlorophyll, and particulate matter and decline in dissolved oxygen, associated with cultural eutrophica-tion. A long-term study is documenting changes in these parameters: previous papers Verity (Estuaries 25:944–960, 2002a, Estuaries 25:961–975, b) reported on hydrography, nutrients, chlorophyll, and particulate matter during 1986– 1996; plankton community responses are reported here. Phytoplankton, bacteria, heterotrophic nanoplankton and dinoflagellates, ciliates, and copepods exhibited strong seasonal cycles in abundance driven by temperature and resource availability, typically with summer maxima and winter minima. However, cultural eutrophication coincided with altered planktonic food webs as autotrophic and heterotrophic communities responded to increasing concen-trations and changing ratios of inorganic and organic nutrients, potential prey, and predators. Small (<8 μm) photosynthetic nanoplankton increased in absolute concen-tration and also relative to larger cells. In contrast, diatoms did not show consistent increases in abundance, despite significant long-term increases in ambient silicate concen-trations. Mean annual bacteria concentrations approximate-ly doubled, and eukaryotic organisms in the microbial food web (heterotrophic and mixotrophic flagellates, dinoflagel-lates, ciliates, and metazoan zooplankton) also increased. All plankton groups except copepods showed trends of increasing annual amplitudes between seasonal high and low values, with higher peak concentrations each year. These observations suggest that the eutrophication signal was gradually becoming uncoupled from regulatory mech-anisms. Theory and evidence from other more impacted waters suggest that, if these patterns continue, changes in the structure and function of higher trophic levels will ensue.
... Intra-annual temperature control of bacterioplankton biomass and its production has been derived from several field studies based on observed correlations (Findlay et al. 1991, White et al. 1991, Ducklow & Shiah 1993, Hoch & Kirchman 1993, Turner & Borkman 1993. In contrast to this evidence, correlations between phytoplankton carbon fixation and bacterial biomass production are lacking. ...
Field data from a 1.5 yr intensive study of 1 coastal (0 to 20 m) and 2 offshore stations (0 to 100 m) in the northern Baltic were analysed. Specific interest was paid to the difference in the spatiotemporal variation of bacterioplankton and its controlling factors. Less than 31% of the annual bacterial biomass production (P-b) occurred in the photic zone during the productive season at the offshore stations. This suggested an uncoupling between P-b and phytoplankton carbon fixation, which was further supported by the lack of a significant correlation between these variables in the photic zone. The basin with high allochthonous loading and long residence time showed high P-b relative to autochthonous carbon fixation and low variance of P-b and bacterial abundance (N-b), suggesting an important contribution of terrestrial dissolved organic carbon to the carbon and energy supply. Bacterial per capita growth rate (r(c)) was highest during spring, while P-b was highest during summer at all stations. The seasonal variation in P-b was mainly explained by variation in the r(c), rather than in N-b. A positive correlation of N-b with temperature. and a negative correlation with salinity, suggested that >61% of the seasonal variation in N-b was a consequence of the formation of a stratified photic zone with a higher carrying capacity. Temperature limitation of r(c) only occurred in the stratified photic zone, suggesting that other growth factors were sufficient during this period. A density limitation of the maximum r(c) was observed at all stations during autumn and winter in both depth layers, suggesting competition to be of periodic importance. Bacterioplankton with a low r (intrinsic growth rate) and high K (carrying capacity) strategy dominated when sedimenting particles were a major resource in the aphotic zone, while the opposite strategy dominated during winter at low cell densities, when dissolved substrates were the major resource.
... We observed high concentrations of chlorophyll in WIS sediments during spring (Fig. 5, left) indicating the presence of fresh algal material, although this chlorophyll may have come from the deposition of planktonic algal material, the presence of benthic diatoms, or both. Diatoms were present at WIS in the spring of 1989 (personal observation) and in 1990 (Banta et al., 1994) and the bottom of Buzzards Bay is within the euphotic zone (> 1% surface light) throughout much of the year (Turner and Borkman, 1993). Inputs of fresh algal organic matter from benthic sources have also been shown to have a similar stimulatory effect on denitrification rates (Jorgensen and Sorensen, 1985) as does the settlement of phytoplankton blooms on the sediment surface, so whether the algal material was of planktonic or benthic origin, denitrification rates were likely to have been stimulated in the spring at WIS. Benthic diatoms present during the spring may have had a second potential effect on N recycling at WIS. Benthic algae might have taken up DIN both from the overlying water (possibly the N03-uptake we measured in March and early May) and from the DIN released by organic matter decomposition (Andersen and Kristensen, 1988; Sundback et al., 1991). ...
... Benthic respiration rates in Buzzards Bay thus reflected the current mineralization of a small amount of reactive organic matter that was recently deposited, but not easily measurable within the bulk pool of refractory organic matter within the sediment. For example, benthic respiration rates and pigment concentrations differed between stations in August 1989 by factors of 1.5 and 2, respectively, while POC concentrations differed by a factor of 8. Furthermore, lower benthic respiration rates and thus slower rates of organic matter decomposition are consistent with lower concentrations of chlorophyll a in the water column and lower rates of primary production in Buzzards Bay compared to many other coastal environments (Roman and Tenore, 1978; Borkman and Turner, 1993). Phytoplankton pigments appear to be much better indicators of the deposition of fresh, labile planktonic organic matter than bulk sediment parameters such as POC in Buzzards Bay. ...
Benthic flux rates measured at 12 sites in Buzzards Bay during August 1989 varied by less than a factor of two for benthic respiration and less than a factor of three for DIN release. The only environmental factor that emerged from path analysis as related (negatively) to the spatial pattern of benthic flux rates in August was water depth. The combination of seasonal and spatial observations indicate that the processes oxidizing organic matter in Buzzards Bay sediments are controlled by temperature and the delivery of labile organic matter to the sediment surface. Benthic flux rates in Buzzards Bay were generally low, but N recycling efficiency was high, relative to similar coastal environments. -from Authors
Applications of numerical models to predict and eventually manage the onset, duration, and consequences of toxic phytoplankton events of coastal ecosystems require knowledge of both the ecophysiological properties of the specific organisms and the biophysical processes, which allow them to accumulate large biomass, despite the presence of other competitors. Harmful algal blooms are not always just local events. Furthermore, independent in situ plankton data sets from the Gulf of Mexico (GOM) and Mediterranean Sea over six decades, together with adjunct satellite color data, other nitrogen isotope signals of plankton and sediments, extant circulation models, and phytoplankton biomarkers within sediment cores of this similar ecosystem, all confirm the complex western GOM eutrophied sequence of phytoplankton succession.
Monthly sampling for ichthyoplankton was conducted at 8 stations in Buzzards Bay, Massachusetts, from October 1987 to September 1993 using a 48 cm diameter plankton net with 0.102 mm mesh. From October 1992 to September 1993, an additional 75 cm diameter net with 0.202 mm mesh was also towed to compare mesh selectivity. Stations included two with heavy anthropogenic impact, the urbanized inner harbor of New Bedford, Massachusetts, and over New Bedford's offshore sewage outfall, as well as other nearshore shallow and offshore deep stations in comparatively pristine areas of the bay. Fish larvae from 32 genera were identified. Fish eggs were counted but not identified. There was a pronounced summer peak in larval abundance dominated by cunner Tautogolabrus adspersus, anchovy Anchoa sp. and tautog Tautoga onitis. A smaller winter/early spring peak was dominated by sand lance Ammodytes sp. This pattern was evident for all 6 years of the study. The assemblage of fish larvae found in Buzzards Bay differed from that in Cape Cod Bay, lending support to the concept of Cape Cod as a faunal boundary. The 2 differently sized nets used during the last year of the study did not catch significantly different numbers of fish larvae per ml, but length frequency distributions of 4 abundant species of larvae revealed that the smaller mesh net caught significantly smaller Anchoa sp. The larger mesh net collected significantly more species of fish larvae. A comparison of annual mean catches of 4 species did not reveal significant changes in abundance over 6 yr.
From October 1987 through September 1998, phytoplankton composition, inorganic nutrients, temperature, salinity, water clarity, and chlorophyll a (chl a) + phaeopigments were monitored during 141 monthly cruises in Buzzards Bay, Massachusetts, USA. There were large seasonal and interannual variations in nitrate, silicate and phytoplankton abundance and composition. There were no consistent interannual patterns of recurrent spring blooms, measured as either chl a or phytoplankton cell abundance. Rather, blooms of various taxa were sporadic, particularly diatom blooms in the late summer and fall. Other parameters were similar bay-wide on a given day, and over seasons and years for stations away from New Bedford Harbor, but concentrations of ammonium, phosphate, and chl a were elevated at the New Bedford sewage outfall, prior to its conversion to secondary treatment in September 1996. After conversion, increased water transparency and decreased levels of ammonium indicated improved water quality at the outfall. Bay-wide chl a and nitrate had significant declines over time from the late 1980s to the late 1990s. There were no significant linear trends with time for annual means of temperature, but there was a significant trend of increased warming in spring. Phytoplankton abundance (0.012 to 26.0 x 10(6) cells l(-1), 1988 to 1998) was higher than reported in other coastal waters of New England, due to preservation that did not destroy the delicate microflagellates and phytoflagellates which dominated phytoplankton abundance. Potentially harmful algal species included diatoms of the genus Pseudo-nitzschia, and the dinoflagellate Alexandrium fundyense. Buzzards Bay is a favorable habitat for phytoplankton in that it is well-mixed and well-illuminated, and nutrient-replete.
Dinoflagellates were counted and identified in >20 mum samples from Buzzards Bay, Massachusetts, USA, from October 1987 to September 1988. Eight stations were sampled at monthly or twice-monthly intervals. Dinoflagellates were the most abundant organisms in the >20 mum microplankton samples (excluding diatoms), comprising up to 99% of total organisms. A total of 46 dinoflagellate species from 19 genera were recorded, and there were dinoflagellate blooms throughout the year. Bloom-forming taxa included Gymnodinium sanguineum, Heterocapsa triquetra, Prorocentrum minimum, and Prorocentrum triestinum. Mean annual dinoflagellate abundance was 9.7 x 10(3) cells l-1, but blooms reached concentrations of 10(5) cells l-1. Dinoflagellates were most abundant from spring to fall, and dinoflagellate blooms developed in between diatom blooms, coinciding with increasing silicate concentrations. This suggests that after silicate depletion by diatom blooms, dinoflagellates were able to exploit an undersaturated phytoplankton niche. Dinoflagellates were much more abundant at the New Bedford sewage outfall and in New Bedford Harbor than in the rest of the bay. The effect of concentrating dinoflagellate samples with a 20 mum mesh screen was examined by comparisons of abundance of selected taxa in screened and unscreened whole-water samples concentrated by sedimentation. There were no significant differences between screened and whole-water samples (2-way ANOVA for paired comparisons) for total dinoflagellates, or for 5 abundant taxa.
As part of a larger study of hydrography, water chemistry and plankton in Buzzards Bay, Massachusetts, USA, we quantified levels of nutrients (ammonium, nitrate, nitrite, orthophosphate, silicate), chlorophyll a and phaeopigments from 1 October 1987 to 11 September 1990 (n = 1080 for each parameter). Although there were considerable monthly, seasonal and interannual fluctuations of some variables, certain trends were apparent. Ammonium comprised up to 99.79 % (mean = 75.79 %) of total dissolved inorganic nitrogen (DIN = NH4+ + NO3- + NO2-). This was due to nutrient loading at one station from a sewage outfall, and to resuspension of benthic nutrients due to shallow depth and frequent mixing throughout the entire bay. Nitrate levels were maximal in winter, whereas those of orthophosphate were higher during the warmer months. Both variables exhibited interannual variation. Silicate exhibited sustained bay-wide summer increases in all 3 years, followed by precipitous declines in autumn. Inverse relationships between silicate and diatoms during 1987 to 1988 suggest that silicate fluctuations were biologically related, in that the summer increase was a rebound from heavy utilization during the spring diatom bloom, and the autumn silicate decline was due to utilization by a fall diatom bloom. Chlorophyll a levels were comparatively high (>5.0 mg 1-1) and relatively uniform throughout the bay except for higher concentrations near the sewage outfall, or within an enclosed harbor where a hurricane dike appears to increase residence times of phytoplankton blooms by reducing circulation. Buzzards Bay is a habitat favorable to high phytoplankton production because shallow depth and frequent mixing result in a water column that is holomictic and euphotic throughout most of the year, and the sediments act as a nutrient pump injecting ammonium and other remineralized nutrients into the water column.
Tintinnids were collected from Buzzards Bay, Massachusetts, USA, from October 1987 to September 1988. Tintinnids were collected by screening 3 l of seawater with a 20 mum mesh. Eight stations throughout the bay were sampled at monthly or twice-monthly intervals. A total of 30 species of tintinnids were recorded, half of which were members of the genus Tintinnopsis. Tintinnid abundances ranged from 0 to 3.3 x 10(3) cells l-1. Tintinnids were least abundant at the Cape Cod Canal and in northern Buzzards Bay, and most abundant at the New Bedford sewage outfall. Unlike dinoflagellates, tintinnids did not show higher abundances in New Bedford Harbor than in the main part of the bay. The effect of screening tintinnid samples with a 20 mum mesh screen was examined by comparisons of abundance of tintinnids in screened and unscreened whole-water samples concentrated by gravitational sedimentation. Tintinnid abundance estimates were significantly higher in the screened samples.
