Spring Bloom Period Research Articles

Ultraviolet-B radiation enhancement does not affect marine trophic levels during a winter-spring bloom

:Elevated UV-B radiation levels (~100% above ambient) generally failed to produce significantly different effects at different trophic levels in well-mixed mesocosms during the winter spring bloom period. Although not significantly different, several consistent trends were noted. Phytoplankton abundance, measured as total cell counts, and biomass, measured as in vivo fluorescence, tended to be reduced in UV-B enhanced treatments. Effects were significantly different for fluorescence (p < 0.05) during the bloom event but not abundance (p = 0.29) and not over the entire experiment. There was a tendency for the ratio of nanoplankton to microplankton biomass to be lower in UV-B enhanced systems (p = 0.16). Total copepod abundance (adults, copepodites and nauplii) and abundance of the dominant species, Acartia hudsonica (Giesbrecht), also tended to be lower in the treatment mesocosms. Significant differences (p < 0.05) in copepod abundance between controls and treatments were observed in the adult stage prior to and during the bloom event. Survival of winter flounder (Pleuronectes americanus [Walbaum]) eggs incubated at 0.1 and 0.5 m depths was significantly lower in UV-B elevated mesocosms (p < 0.05) while no significant differences were observed at greater depths (p = 0.55). Survival and growth of winter flounder larvae added to the mesocosms during the final three weeks of the experiment did not vary significantly between controls and treatment mesocosms.

Production pattern of alkenones in the Mediterranean Sea

Time‐series of downward alkenone fluxes have been investigated at 200 m depth over a one year sediment trap experiment, in the Northwestern Mediterranean Sea. Alkenone flux maxima occurred in autumn and to a lesser extent in May, during the spring bloom. Temperature estimates calculated from the UK′37 index revealed that alkenone producers preferentially develop in subsurface waters (at about 50 m) in spring, whereas the autumn alkenone production occurred upper in the water column (around 30 m). Examination of the core‐top UK′37 index values at various sites of the Northwestern Mediterranean basin, suggested that the spring bloom period do not significantly imprint the temperatures recorded in the sediments. The sedimentary temperature estimates would rather reflect annually integrated SST, with a major influence of the autumnal post‐bloom development of the coccolithophores in the euphotic zone.

Seasonal and environmental influences on antioxidative protection inPeridinium gatunense in Lake Kinneret

As the only freshwater lake in Israel, Lake Kinneret serves a number of important functions which directly rely upon the viability of the water. The annual outbreak of a dinoflagellate bloom strictly governs the nature of the macro and micro food web and ultimately determines water quality. The freshwater dinoflagellate Peridinium gatunense is subject to a wide range of environmental stresses throughout the spring bloom period. It was confirmed that SOD played an important antioxidative maintainance role throughout the bloom, especially during periods of relatively high photosynthetic activity (820 mg C m -2 day -1 ), when activity reached ∼500 Units SOD mg protein -1 . In addition, high light stress (>300 μmol photons m -2 s -1 ) induced SOD activity, despite the low dissolved inorganic carbon (DIC) concentrations at the end of the bloom (1.3 mM). Catalase activity was only significant at the end of the bloom, peaking at 120 μmol 02 mg protein -1 min -1 , when induced by photorespiratory activity. A series of experiments with Peridinium cultures showed that 2 x 10 -4 M ascorbate inhibited catalase activity >50% within 15 min incubation, both in vivo and in vitro. It is suggested that the high concentrations of ascorbate, found previously in Peridinium during early and mid-bloom (0.2-1.6 mM), not only eliminate H202 build-up, but also prevent (directly or indirectly) the induction of catalase.

Dissolved organic carbon on Georges Bank

Dissolved organic carbon (DOC) in sea water from Georges Bank was measured by a high temperature combustion/direct injection (HTC/DI) technique during the spring bloom period in April 1993. Concentrations in surface waters (72–85 μM) and deep waters (54–56 μM) were similar to DOC concentrations measured in the oligotrophic north-west Atlantic Ocean by a number of other investigators by various techniques. Although surface values for Chl- a concentrations ranged from 2 to 5 μg l −1, NO 3 − ranged from 3 to 9 μM and particulate organic carbon (POC) concentrations ranged from 1.0 to 10μM, DOC concentrations only varied by <18‰ DOC was slightly higher (∼5 μM) in the highly productive central bank region than in surrounding stratified surface waters. Relatively constant stable carbon isotopes (DO 13C = −22.0 ± 0.5 could not be used to identify a source for these small variations. Slight decreases of DOC (5–12μM) and dissolved organic nitrogen (DON) (0.5–1.0 μM) in filtered sea water kept in the dark was observed over six months, suggesting the presence of a small, labile pool of dissolved organic matter in addition to a large, more refractory reservoir of DOC (∼70 μM) during the spring bloom period on Georges Bank.

Diel feeding behavior of neritic copepods during spring and fall blooms in Akkeshi Bay, eastern coast of Hokkaido, Japan

In situ diel feeding behavior of neritic copepods was investigated using the gut fluorescence method, during spring and fall bloom periods in Akkeshi Bay, on the eastern coast of Hokkaido, Japan. Acartia omorii and Paracalanus sp. were the dominant species during the fall, and Pseudocalanus spp. and A. longiremis during the spring. During both bloom periods, diel rhythms were always observed for the gut pigment contents of these dominant copepods, although there were interspecific differences in the pattern. The maximum gut pigment content was always observed during the night and the minimum during the day. For all species, except Paracalanus sp., the average gut pigment content during the night was significantly higher (p<0.05) than during daytime by factors of between 1.5 and 2.7. There were no significant differences between the gut evacuation rate constants determined during the day and the night, and initial gut pigment content had no effect on the value of gut evacuation rate constants. The instantaneous ingestion rates of individual copepods calculated from gut pigment and the mean value of gut evacuation rate constants followed the same diel rhythms as gut pigment contents. Copepod daily ingestion rates were higher than the daily requirements for respiration during both bloom periods. Estimated daily ration was 40 to 91% of body carbon during the fall bloom, and 17 to 28% during the spring bloom. The higher daily rations during fall were probably due to the difference in in situ temperature (ca. 14°C).

Contamination of sediment trap fluxes by vertically migrating phototrophic micro-organisms in the coastal Baltic Sea

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 122:45-58 (1995) - doi:10.3354/meps122045 Contamination of sediment trap fluxes by vertically migrating phototrophic micro-organisms in the coastal Baltic Sea Heiskanen AS Sedimentation rates of phytoplankton and particulate organic carbon (POC) were studied in the northern Baltic Sea, SW coast of Finland, during the spring bloom and early summer periods in May and June 1988. Sediment traps were moored at 15 and 30 m depths, and the cylinders were either preserved with formaldehyde (F) or remained as unpreserved control cylinders (C). The phytoplankton spring bloom in May was dominated by motile dinoflagellates. Due to the high abundance and vertical migration of the chain-forming dinoflagellate Peridiniellacatenata, the POC fluxes measured by the F-cylinders were, on average overestimated by 12%, and at most by 32% during the spring period. Between 3 and 12% of the P. catenata population was estimated to migrate daily below 15 m depth; part of the population also reached 30 m depth. Another migrating phototrophic organism present in the water column was the ciliate Mesodiniumrubrum. Generally, a larger fraction of the M. rubrum population (2 to 26%) migrated, but they did not contaminate the measurements to the same degree as P. catenata (&LT3% of total POC fluxes) due to their lesser abundance in the water column. In June, Eutreptiella sp. (Euglenophyceae) had significantly higher cell numbers in the F- than in the C-cylinders. They were estimated to contaminate the POC fluxes up to 13% at 15 m depth (F-cylinder). The difference in the Eutreptiella cell numbers between the 2 treatments could have been partly due to increased copepod grazing rates inside the C-cylinders (up to 90% of the total difference if they fed on phytoflagellates only). Contamination caused by the total apparent vertical migration of P. catenata, M. rubrum and Eutreptiella sp. accounted for 17 and 12%, on average, of the total POC sedimentation (F-cylinders) at 15 and 30 m depths, respectively. This study indicates that vertical migration of the phototrophic micro-organisms can significantly bias sediment trap measurements in shallow coastal areas where sediment traps are often deployed within the vertical range of the migrating microplankton (i.e. above 30 to 40 m). Sediment traps · Sedimentation · Preservation · Swimmer contamination · Vertical migration · Dinoflagellates · Mesodiniumrubrum · Eutreptiella sp. Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 122. Publication date: June 15, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Comparison of the sedimentation of a diatom spring bloom and of a subsurface chlorophyll maximum

The seasonal pattern of sedimentation was determined over a 8-mo investigation period covering the productive season at a permanent station in the Southern Kattegat (Denmark) in 1990. The phytoplankton succession was characterised by a 4-mo long subsurface maximum associated with the pycnocline which was entirely dominated by the dinoflagellate Gyrodinium aureolum. The bulk sedimentation of organic matter took place during this period and accounted for >60% of the annual particulate organic carbon (POC) and particulate organic nitrogen (PON) sedimentation. The spring bloom period contributed 60% of the sedimentation of intact phytoplankton cells, but only 20% of the POC and PON sedimentation. A minor fraction of the sedimenting matter from the subsurface phytoplankton maximum consisted of intact phytoplankton (<20%), suggesting that the phytoplankton was processed by heterotrophs and that it was mainly products from this activity which contributed to thevertical flux of organic matter. The variation in oxygen concentration below the pycnocline coincided with the pattern of sedimentation with a delay of 3 to 6 wk.

RESPONSE OF CATALASE ACTIVITY TO ENVIRONMENTAL STRESS IN THE FRESHWATER DINOFLAGELLATE PERIDINIUM GATUNENSE1

ABSTRACTCatalase activity increased in Peridinium gatunense (formerly P. cinctum fa. westii) cells during the decline of the seasonal spring bloom period in Lake Kinneret. This was correlated with the low ambient total CO2 concentration. The relationship was confirmed in laboratory experiments where maximum catalase activity occurred under an atmosphere composed of 30% O2 and 0.003% CO2. Conversely, high CO2 concentrations inhibited catalase activity. The rise in catalase activity was not directly due to increasing environmental pH, as in vitro and in vivo measurements showed a characteristic broad pH curve with a constant activity from pH 6–10 for catalase.Photoinhibition of catalase occurred above 250 μmol photons · m−2· s−1. However, at high photoinactivating irradiances, photoinhibition was ameliorated under high pO2/pCO2. Such conditions prevail in the Kinneret at the end of the spring. We propose that the enhancement of photorespiration (under high pO2/pCO2) induces a temporary burst in catalase activity despite the progressively photoinhibitory conditions of early summer.

Temporal variability in copepod fecundity during two different spring bloom periods in coastal waters off Plymouth (SW England)

Temporal variability in copepod fecundity during two different spring bloom periods in coastal waters off Plymouth (SW England)

Interannual differences in prey taken by capelin, herring, and red salmon relative to zooplankton abundance during the spring bloom in a southeast Alaskan embayment

Capelin, herring, and red salmon diets were examined in relation to zooplankton abundance and biomass in the water column and surface layer of Auke Bay, Alaska, during the spring bloom period, 1987 and 1988 (April through mid-June). Euphausiid eggs were the dominant prey of capelin in mid-May 1987. Pseu-docalanus spp. and barnacle nauplii dominated during the rest of the season. Capelin consumed Calanus spp. and Metridia spp. in April and Pseudocaknus and Cen-tropages abdominalis in May and June 1988. During May and June 1987, herring were eating primarily barnacle larvae and Oikopleura spp. During April 1988, herring consumed primarily Calanus spp. and barnacle nauplii. In late April and early May they shifted to Pseudocalanus and Thysanoessa raschii, and in late May and June they consumed Centropages abdominalis and barnacle cyprids. Outmigrating red salmon fry consumed primarily Oikopleura during both years, along with substantial quantities of barnacle larvae. These dietary changes roughly correspond with variations in the abundance of prey taxa in the plankton samples. Likelihood measures of niche breadth indicated that capelin sometimes consume prey in approximately equal proportions to its abundance. Niche overlap between the herring and capelin was greatest in April and early May. Niche overlap was also high between herring and red salmon during June, when herring were in shallow water to breed.

Energy flow through the SE Kattegat: A comparative examination of the eutrophication of a coastal marine ecosystem

Energy flow through the major compartments of the ecosystem of the south-east Kattegat has been assessed based on observations made between 1985–1989. In this increasingly eutrophic semi-estuarine coastal area, energy inputs are dominated by autochthonous production during the spring and autumn bloom periods (>90%), and by allochthonous fluvial sources during the winter (>50%). An unbalanced annual carbon budget is presented, which demonstrates the predominance of infaunal benthic suspension feeders in the shallow areas (above 13 m), where their demand alone is 2.4 times the calculated carbon supply to the sediment. Benthic demand does not diminish below 13 m, but the proportion utilized by macrofaunal deposit feeders and meiofauna increases with lower suspension feeder demand, emphasizing the close coupling between pelagos and benthos at all depths in this system. Excess benthic demand over planktonic production is assumed to be met by lateral imports across the system boundaries. Intermittent summer hypoxia below the halocline (mean depth 15 m) has a severe effect on the benthos of the area, leading to a reduction in epifaunal predation prior to the reduction of macrobenthic organisms. Such events lead to the temporary accumulation of sedimentary carbon before late autumnal mixing initiates the reoxygenation and eventual recolonization of the affected areas. Comparisons with published carbon budgets for the Chesapeake Bay and the Baltic Sea suggest major differences between the relative roles of pelagos, and benthos in these systems. In the Baltic, which is fuelled predominantly by autochthonous processes, pelagic carbon flows are about 4 times those of the benthos. Allochthonous inputs predominate throughout much of the year in the Chesapeake Bay, where pelagic flows are proportionately 1.5 × those of the benthos, whereas in the SE Kattegat benthic flows exceed those within the pelagos by about 25. The higher populations of epifaunal and nektonic predators found in the SE Kattegat system, as opposed to the other two systems, is a corollary of the greater energy flows through the benthic components. The demonstrable vulnerability to anoxia of these commercially important organisms emphasizes the sensitivity of such coastal systems to the consequences of increased nutrient inputs.

Nutrient Interactions and Phytoplankton Growth during the Spring Bloom Period in Lake Erken, Sweden

Factorial enrichment experiments with nitrate-N, phosphate-P and selenite-Se, were conducted in situ, with natural phytoplankton assemblages, during two consecutive spring-bloom periods (1983 and 1984) in Lake Erken, Sweden. Nutrient conditions, biomass indicators and algal physiological status, in experiments and in lake water, were compared. Characteristic peaks of phytoplankton, dominated by diatoms, developed in the lake in both years. In 1984, chlorophyll a biomass (30 μgl−1) reached almost twice that of 1983 (17 μgl−1). Inorganic P resources were depleted in both years, but inorganic N was exhausted only in 1984. In 1983, Stephanodiscus hantzschii GRUN v. pusillus GRUN. KRIEGER completely dominated the biomass peak. In 1984, Melosira islandica v. helvetica O. MULL occurred in great numbers along with S. hantzschii v. pusillus. The growth rate of S. hantzschii v. pusillus, surplus phosphorus dynamics and potential alkaline phosphatase activity were different during the two spring periods. In the experiments, eight alternative nutrient situations were tested during four phases of the natural phytoplankton development. The algae responded to enrichments during the entire phytoplankton bloom in 1983 and 1984. Nutrient interactions were important, especially in 1983, and occurred most frequently during the late exponential phase, biomass maximum and declining phase in both years. Interactions between N and P were most common in 1983, occurring during the late exponential phase and biomass maximum. N and Se interaction occurred occasionally. Interactions between P and Se were more frequent in 1983 than in 1984. When nutrients interacted, the combined effect was generally smaller than the sum of their individual effects. P deficiency indicators and the experiments showed clearly that the bloom of 1983 was P limited. In 1984 no such clear pattern was found.

Growth, development and distribution of the euphausiids Thysanoessa raschi (M. Sars) and Thysanoessa inermis (Kr�yer) in the southeastern Bering Sea

The distribution and abundance of the euphausiids Thysanoessa raschi and Thysanoessa inermis in the shelf waters of the southeastern Bering Sea were investigated during spring and summer of 1980 and 1981. Experiments were conducted during the study to describe the reproduction, growth and development of these species. T. inermis was the dominant euphausiid species observed over the outer shelf region; it began spawning in early April while T. raschi dominated the euphausiids over the middle shelf and began spawning in mid or late May. The seasonal progression in spawning followed the seasonal development of temperature; however, spawning did not begin earlier in 1981 which was a warmer year than 1980. Average egg production of T. raschi ranged from 3.4% to 3.8% dry body weight of the female per day during the first three days after capture. Secondary production estimates for T. raschi females ranged from 4.2% to 5.2% dry body weight per day in 1980 and 5.9% to 6.0% dry body weight per day in 1981. A sharp decline in the abundance of adolescent and adult euphausiids over the middle shelf during the spring bloom period when food appeared to be abundant suggests that predation by diving birds, pollack. Tanner crabs, whales and seals effectively controls the euphausiid population.

Dissolved and particulate DNA dynamics during a spring bloom in the Antarctic Peninsula region, 1986–1987

Dissolved and particulate DNA (D-DNA and P-DNA, respectively) concentrations were measured at 69 stations in a 25,000 km 2 section of Bransfield Strait, during the austral summer period (December 1986 to March 1987). During the development of the seasonal spring bloom of phytoplankton (December and January), surface water P-DNA (0.2–202μm) exhibited an order-of-magnitude concentration gradient, from values of ≥25 μg DNA I −1 in the productive coastal water near the northern end of Gerlache Strait to ≥4 μg DNA l −1 in the more oligotrophic waters of Drake Passage. P-DNA concentrations were highly correlated with other biochemical indices of microbial biomass (e.g. chlorophyll α and ATP). A majority (≥50%) of the P-DNA was contained in the 0.2–20 μm size category. Estimates derived from DNA:ATP ratios and from direct measurements of bacterial cell abundance suggest that most of the P-DNA during the spring bloom period was associated with living phytoplankton cells, with little, if any, non-living, P-DNA. In contrast to these characteristics of the spring bloom period. P-DNA during post-bloom conditions (March) was low (4–6 μg DNA l −1) and nearly constant throughout our study area, was nearly exclusively (≥80%) contained in the 0.2–20 μm size category, and was nearly exclusively (≥90%) comprised of non-living DNA. D-DNA was ubiquitously distributed in the near-surface waters throughout the RACER study area in December, with concentrations ranging from 6 to 16 μg DNA l −1. However, there was no spatial correlation with either microbial biomass or microbial productivity. By January, surface water D-DNA concentrations had decreased to values ≤10% of the December values (≤1 μg DNA l −1 and by the February to March sampling periods, D-DNA was undectetable throughout our study areas (≤0.1 μg DNA l −1). The dynamics of the D-DNA pools were not well correlated with microbial biomass and production. Rather, the seasonal D-DNA distributions appeared to be controlled by the advection of D-DNA enriched water masses across our study area in December, followed by replacement with D-DNA depleted waters. We hypothesize that the early season D-DNA may be derived from microbial communities in melting ice or from diagenesis in shallow benthic habitats. The results of a box model calculation of P-DNA and D-DNA inventories and fluxes in Bransfield Strait suggest that the northern Gerlache Strait is a major exporter of P-DNA, either as a result of horizontal advection or active transport of macrozooplankton populations.

Seasonal coupling of organic matter production and particle flux in the western Bransfield Strait, Antartica

Simultaneous measurements of seasonal depletions in dissolved inorganic carbon (ΣCO 2), nitrogen [NO 3 − + NO 2 −] and phosphate (HPO 4 2−) and concentrations of C, N and P collected using sediment traps at five representative sites in a 25,000 km 2 sector of the western Bransfield Strait over a 4-month period have allowed us to evaluate the coupling between primary production and particle flux. During the spring bloom period (December to January), we observed a substantial removal of ΣCO 2, [NO 3 − + NO 2 −] and HPO 4 2− corresponding to a net upper water column (0–50 m) seasonal production of 8410 mmol C m −2, 827 mmol N m −2 and 53.1 mmol P m −2. This equates to an average C:N:P ratio of 158:15.6:1. These C:N (and C:P) ratios are higher than the expected Redfield ratios and also exceed the C:N and C:P ratios directly measured for suspended and sinking particles. We hypothesize a coupled formation of carbon-rich dissolved organic matter as a sink for approximately 30–50% of the ΣCO 2 removed during net photosynthesis. The rapid production and accumulation of phytoplankton in the northern portion of Gerlache Strait during the spring bloom resulted in a substantial pCO 2 undersaturation ( pCO 2 ≤ 100 μatm) compared to surface samples collected from lower productivity areas in Drake Passage ( pCO 2 ≥ 325 μatm). Nevertheless, CO 2 invasion from the atmosphere was minimal, in part due to the fact that there was little or no wind-driven mixing at this time of the year. Particulate C, N, P and ATP fluxes derived from free-floating sediment traps, revealed a substantial variability in time and space. The greatest seasonal variation occurred at the stations with the highest rates of primary production. For example, both the highest (31.1 mmol C m −2 day −1) and lowest (<3.0 mmol Cm −2 day −1) rates of POC flux were measured in the northern portion of Gerlache Strait; the other sites exhibited moderate (4.1–12.5 mmol C m −2 day −1) but more constant fluxes during the period of our observations. Nevertheless, the total seasonally integrated C and N fluxes were nearly identical (1.3–1.5 mol C m −2 and 0.16 mol N m −2). For the northern Gerlache Strait station, new production was 26% of total production during the December to January spring bloom period.

Copepod feeding patterns before and during a spring bloom in Bedford Basin, Nova Scotia

Samples of zooplankton were collected at frequent ~ntervals in the top 30 m of Bedford Basin over one 48 h and two 24 h sampling periods in February, early March and late March, 1986. Measurements of gut pigment content showed that Pseudocalanus sp. and Acartia sp. in early March had bimodal diurnal feeding rhythms, with peaks in activity at around dawn and dusk, while in February and in late March they appeared to be feeding more-or-less continuously. The sampling series covered the period of the algal spring bloom and maximal ambient chlorophyll concentrations measured in the top 30 m increased from 3.5 pg I-' in February to 21.0 pg I-' in early March, decreasing to 12.8 pg I-' in late March. We suggest that the diurnal feeding rhythms found in early March resulted from an imbalance between the ability of copepods to ingest food, which would have incrt,ased rapidly during the early spring bloom as phytoplankton levels increased, and their capacity to digest it. Later on in the bloom period, it seems that ingestion and digestion rates became bdlanced again so that diurnal rhythms were not apparent in late March. Such an effect may have been due to adaptive processes occurring in the digestive physiology of the copepods a s the result of exposure to high food concentrations, or perhaps to changes in the composition of the food itself. Related laboratory experiments showed that hunger and light intensity both affected feechng behavior in vitro in a way consistent with that observed In situ

Do continental shelves export organic matter?

It has been suggested that biological production and consumption of organic matter is not balanced in coastal marine ecosystems1,2. If, as suggested, 90% of the phytoplankton produced during the spring bloom period were exported, excess organic carbon would be sequestered on the continental slope below the permanent thermocline. Here we summarize the shelf-edge exchange processes (SEEP) experiment, designed to test the export hypothesis. The absence of a positive imbalance in the organic carbon budget, reinforced by modest sediment deposition and biomass on the continental slope, led us to reject the concept. Only a small fraction of continental shelf phytodetritus is exported; that not consumed in the spring is for the most part used on the continental shelf during the ensuing stratified season. The original hypothesis failed to recognize the contribution of pelagic microbial consumption and the lag in coupling between seasonal production and consumption processes.