Taxon-specific growth and selective microzooplankton grazing of phytoplankton in the Northeast Atlantic

Gaul, Wilhelm; Antia, Avan

doi:10.1016/s0924-7963(01)00061-6

Cited by 35 publications

(18 citation statements)

References 78 publications

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“…These values fall within the range of grazing estimates from other coastal ecosystems (Burkill et al, 1987;Anderson et al, 1991;McManus and Ederington-Cantrell, 1992;Strom and Strom, 1996;Murrell and Hollibaugh, 1998;Strom et al, 2001;Gaul and Antia, 2001). In addition, this study shows microzooplankton grazing behavior can be a structuring mechanism controlling the composition of microplankton communities.…”

Section: Discussionsupporting

confidence: 77%

Phytoplankton growth, microzooplankton herbivory and community structure in the southeast Bering Sea: insight into the formation and temporal persistence of an Emiliania huxleyi bloom

Olson

Strom

2002

Deep Sea Research Part II: Topical Studies in Oceanography

143

108

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Using the seawater dilution technique, we measured phytoplankton growth and microzooplankton grazing rates within and outside of the 1999 Bering Sea coccolithophorid bloom. We found that reduced microzooplankton grazing mortality is a key component in the formation and temporal persistence of the Emiliania huxleyi bloom that continues to proliferate in the southeast Bering Sea. Total chlorophyll a (Chl a) at the study sites ranged from 0.40 to 4.45 mg C l À1 . Highest phytoplankton biomass was found within the bloom, which was a mixed assemblage of diatoms and E. huxleyi. Here, 75% of the Chl a came from cells >10 mm and was attributed primarily to the high abundance of the diatom Nitzschia spp. Nutrient-enhanced total phytoplankton growth rates averaged 0.53 d À1 across all experimental stations. Average growth rates for >10 mm and o10 mm cells were nearly equal, while microzooplankton grazing varied among stations and size fractions. Grazing on phytoplankton cells >10 mm ranged from 0.19 to 1.14 d À1 . Grazing on cells o10 mm ranged from 0.02 to 1.07 d À1 , and was significantly higher at non-bloom (avg. 0.71 d À1 ) than at bloom (avg. 0.14 d À1 ) stations. Averaged across all stations, grazing by microzooplankton accounted for 110% and 81% of phytoplankton growth for >10 and o10 mm cells, respectively. These findings contradict the paradigm that microzooplankton are constrained to diets of nanophytoplankton and strongly suggests that their grazing capability extends beyond boundaries assumed by size-based models. Dinoflagellates and oligotrich ciliates dominated the microzooplankton community. Estimates of abundance and biomass for microzooplankton >10 mm were higher than previously reported for the region, ranging from 22,000 to 227,430 cells l À1 and 18 to 164 mg C l À1 . Highest abundance and biomass occurred in the bloom and corresponded with increased abundance of the large ciliate Laboea, and the heterotrophic dinoflagellates Protoperidinium and Gyrodinium spp. Despite low grazing rates on phytoplankton o10 mm within the bloom, the abundance and biomass of small microzooplankton (o20 mm) capable of grazing E. huxleyi was relatively high at bloom stations. This body of evidence, coupled with observed high grazing rates on large phytoplankton cells, suggests the phytoplankton community composition was strongly regulated by herbivorous activity of microzooplankton. Because grazing behavior deviated from size-based model predictions and was not proportional to microzooplankton biomass, alternate mechanisms that dictate levels of grazing activity were in effect in the southeastern Bering Sea. We hypothesize that these mechanisms included morphological or chemical signaling between phytoplankton and micrograzers, which led to selective grazing pressure. r

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Section: Discussionsupporting

confidence: 77%

Phytoplankton growth, microzooplankton herbivory and community structure in the southeast Bering Sea: insight into the formation and temporal persistence of an Emiliania huxleyi bloom

Olson

Strom

2002

Deep Sea Research Part II: Topical Studies in Oceanography

143

108

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“…4b) and the nonsignificant relationship of the residuals from m − µ GLMM regressed against body size (p = 0.693) lead us to conclude that the size-specific grazing mortality mainly depends on the size-specific growth rate but not on body size, which is consistent with previous studies indicating that the microphytoplankton size-specific grazing mortality is size-independent (Gutiérrez-Rodríguez et al, 2009McManus et al, 2007). In conclusion, microphytoplankton growth rate might be the most essential characteristic influencing the zooplankton prey selection behaviour (Burkill et al, 1987;Gaul and Antia, 2001;Lie and Wong, 2010;Strom, 2002;Strom and Welschmeyer, 1991), at least in the ECS. Nevertheless, we still caution our interpretation because body size and sizespecific growth rates show a significant, however small, positive relationship (Table 1).…”

Section: Scaling Of Size-specific Growth Rates (µ) and Mortality (M)supporting

confidence: 90%

Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

et al. 2013

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Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of −1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ∼0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by (1) differential grazing mortality of small versus large individuals, (2) differential growth rate of small versus large individuals, or (3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure

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“…The resulting high growth rates of the nongrazed taxa could have exceeded the loss rate of the grazed taxa, leading to apparently higher overall phytoplankton growth in the undiluted treatments with more grazers. It has been demonstrated that micro zooplankton may exhibit selective grazing on phytoplankton taxa, regardless of the relative abundance of the desired taxa (Burkill et al 1987, Verity 1991, Gaul & Antia 2001. Indeed, during our June 2008 experiments, when overall chl a-based phytoplankton growth rates were negative, the taxonspecific grazing rate was high (1.0 d −1 ) on small (<10 µm) diatoms while grazing rates were strongly negative for the other prey taxa (Fig.…”

Section: Phytoplankton Growth and Microzooplankton Grazing Over A Blomentioning

confidence: 63%

Microzooplankton grazing before, during and after a cyanobacterial bloom in Vancouver Lake, Washington, USA

Boyer¹,

Rollwagen‐Bollens²,

Bollens³

2011

Aquat. Microb. Ecol.

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Taxon-specific growth and selective microzooplankton grazing of phytoplankton in the Northeast Atlantic

Cited by 35 publications

References 78 publications

Phytoplankton growth, microzooplankton herbivory and community structure in the southeast Bering Sea: insight into the formation and temporal persistence of an Emiliania huxleyi bloom

Phytoplankton growth, microzooplankton herbivory and community structure in the southeast Bering Sea: insight into the formation and temporal persistence of an Emiliania huxleyi bloom

Scaling of growth rate and mortality with size and its consequence on size spectra of natural microphytoplankton assemblages in the East China Sea

Microzooplankton grazing before, during and after a cyanobacterial bloom in Vancouver Lake, Washington, USA

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