Grazer‐induced aggregation in diatoms

Grønning, Josephine; Kiørboe, Thomas

doi:10.1002/lol2.10282

Cited by 5 publications

(2 citation statements)

References 48 publications

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“…Diatoms have evolved a wide variety of inducible defenses against larger sized predators (e.g., copepods), including shell thickening (Grønning and Kiørboe 2020; Ryderheim et al 2022 a ), domoic‐acid production (Olesen et al 2022), chain‐shortening (Bergkvist et al 2012) and aggregation (Grønning and Kiørboe 2022). However, with the exception of aggregation, none of these seem to have negative effects on smaller protist grazers, such as dinoflagellates and ciliates (Olson and Lessard 2010; Pančić et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Microzooplankton grazers induce chain length plasticity in colonial diatoms

Ryderheim,

Huang,

Selander

et al. 2024

Limnology & Oceanography

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Many diatoms form long chains and the distribution of chain lengths within a species depends on several environmental factors, among them grazing risk. Larger grazers, such as copepods, efficiently handle and ingest even very long chains but are less efficient with individual cells, whereas most smaller grazers are unable to feed on chains exceeding a few cells in length. Copepod cues make several species shorten their chain length, and theory predicts that cues from small grazers should induce increased, but this remains to be tested, despite the importance of diatoms in marine food webs. Here, we expose three species of chain‐forming diatoms, Skeletonema marinoi, Chaetoceros affinis, and Thalassiosira rotula to cues from various actively feeding micrograzers and record their response. The effect of grazer presence on chain length varies depending on both the type of grazer and the diatom species. For example, S. marinoi increased its chain length when exposed to grazing cues from the heterotrophic dinoflagellate Gyrodinium dominans and the ciliate Euplotes sp. but not to a copepod nauplii (Temora longicornis). C. affinis also responded to cues from grazing G. dominans by increasing chain length, and the response increased with exposure time. Finally, T. rotula did not respond to grazing cues from G. dominans, but rather inhibited the dinoflagellates' ability to feed, presumably through the release of chemical compounds. Our results suggest that some chainforming diatoms can sense and appropriately respond to fast‐growing micrograzers, thus contributing to the success of diatoms in marine environments.

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Section: Discussionmentioning

confidence: 99%

Microzooplankton grazers induce chain length plasticity in colonial diatoms

Ryderheim,

Huang,

Selander

et al. 2024

Limnology & Oceanography

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“…Toward the end of the bloom, larger grazers such as copepods increase in numbers, and chain formation becomes obsolete (Ryderheim et al 2022). Thus, the strains responding by breaking up chains (Bergkvist et al 2012), increasing their stickiness, and sinking out of the photic zone away from grazing pressure will secure a large seed population for the next growth opportunity (Grønning and Kiørboe 2022). In a summer bloom of dinoflagellates, the dynamics will work differently.…”

Section: Means Of Coexistence Within Phytoplankton Populationsmentioning

confidence: 99%

Intraspecific genetic diversity and coexistence in phytoplankton populations

Ryderheim,

Kiørboe

2024

Limnology & Oceanography

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The past two decades have seen a drastic increase in the availability and use of genetic techniques to study phytoplankton communities. As a result, it is now well documented that phytoplankton populations are genetically diverse, despite predominantly asexual reproduction and minute morphological variation. Genetic variation can lead to variation also in phenotype, and some traits vary more among genotypes than between species. Trait‐based approaches tackle this by focusing on traits rather than on species. However, trait‐based models often have difficulty predicting and explaining the huge trait‐diversity among coexisting individuals competing for the same few resources. Thus, we ask the question: How do hundreds, if not thousands, of genotypes coexist in a highly competitive environment? In this review, we gather information on genetic and phenotypic variations in coexisting genotypes and elaborate on three mechanisms by which broad intraspecific genetic diversity may be possible: neutral mutations, environmental fluctuations, and trade‐offs among traits. These have all been applied on an interspecies level, and we discuss their use also among coexisting genotypes. We find that genetic diversity to be almost exclusively studied in blooming species and that clonal diversity frequently measure above 0.95 (i.e., 95% of individuals sampled are genetically different). Genetic diversity seems stable throughout blooms, suggesting that competitive exclusion is low or that new genetic material is frequently being introduced into populations. Further, we find high intraspecific trait‐variation in several key traits among coexisting strains but also that trait‐variation is often neglected in studies on phytoplankton, making coexistence difficult to predict.

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Species richness and intraspecific variation interactively shape marine diatom community functioning

Thomas,

Jacob,

Acevedo‐Trejos

et al. 2024

Limnol Oceanogr Letters

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Biodiversity generally increases productivity in ecosystems; however, this is mediated by the specific functional traits that come with biodiversity loss or gain and how these traits interact with environmental conditions. Most biodiversity studies evaluate the effects of species richness alone, despite our increasing understanding that intraspecific diversity can have equally strong impacts. Here, we manipulate both species richness and intraspecific richness (i.e., number of distinct strains) in marine diatom communities to explicitly test the relative importance of species and strain richness for biomass and trait diversity in six distinct temperature/nutrient environments. We show that species and strain richness both have significant effects on biomass and growth rates, but more importantly, they interact with each other, indicating that cross‐species diversity effects depend on within‐species diversity and vice versa. This intertwined relationship thus calls for more integrative approaches quantifying the relative importance of distinct biodiversity components and environmental context on ecosystem functioning.

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Grazer‐induced aggregation in diatoms

Cited by 5 publications

References 48 publications

Microzooplankton grazers induce chain length plasticity in colonial diatoms

Microzooplankton grazers induce chain length plasticity in colonial diatoms

Intraspecific genetic diversity and coexistence in phytoplankton populations

Species richness and intraspecific variation interactively shape marine diatom community functioning

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