Journal of Plankton Research

http://plankt.oxfordjournals.org

List of Papers (Total 2,340)

Daphnia’s challenge: survival and reproduction when calcium and food are limiting

Calcium levels have declined in boreal lakes in North America and Europe due to soil mineral leaching, logging and climate change. Crustacean zooplankton species with high-calcium demand such as Daphnia, are particularly vulnerable to calcium-related stress. In a factorial design, we tested the effects of three calcium concentrations (2.5, 1.0 and 0.5 mg/L Ca) and two food levels...

Trophic positions of mesozooplankton across the North Atlantic: estimates derived from biovolume spectrum theories and stable isotope analyses

The structure of marine pelagic food webs determines the fate of organic carbon and productivity, but it is difficult to measure. We compared two common methods (stable isotope analyses, SIAs, and biovolume spectrum theories, BSTs) of estimating trophic positions (TPs) of mesozooplankton. Two sets of stations across the North Atlantic (Iceland Basin, Irminger Basin, Labrador Sea...

Size-scaling of macromolecules and chemical energy content in the eukaryotic microalgae

The macromolecular composition and cell size of microalgae can influence their competitive interactions for nutrients and food quality for predators. Here we quantify the cell volume and dry weight based size-scaling of protein, lipid, carbohydrate and chemical energy content of eukaryotic microalgae from data extracted from the scientific literature. Across all the microalgae...

Phytoplankton assemblage during the North Atlantic spring bloom assessed from functional gene analysis

The spring bloom in the North Atlantic develops over a few weeks in response to the physical stabilization of the nutrient-replete water column and is one of the biggest biological signals on earth. The composition of the phytoplankton assemblage during the spring bloom of 2008 was evaluated, using a microarray, on the basis of functional genes that encode key enzymes in nitrogen...

Planktonic protists: little bugs pose big problems for biodiversity assessments

The view that current species inventories (lists of binomial species) of planktonic protists significantly underestimate true diversity is widespread. However, the existence of synonyms in species lists, due to repeated descriptions of the same form, and polymorphism in which different “forms” or life-history stages are but one species, are generally underappreciated. Recent...

Species-rich meta-communities of the diatom order Thalassiosirales in the Arctic and northern Atlantic Ocean

The marine planktonic diatom order Thalassiosirales are used as climate proxies with reported characteristic temperate and Polar species. However, a systematic analysis of the genetic variability and species limits is lacking. Here, we combined molecular and morphological approaches to identify Thalassiosirales from 7 Beaufort Sea sea-ice samples and 27 water-column samples...

Predator-specific reversibility of morphological defenses in Daphnia barbata

Inducible defenses are a common phenotypically plastic response to a heterogeneous predation risk. Once induced, these defenses cannot only lose their benefit, but even become costly, should the predator disappear. Consequently, some organisms have developed the ability to reverse their defensive traits. However, despite extensive research on inducible defenses, reports on...

Metabolically active, non-nitrogen fixing, Trichodesmium in UK coastal waters during winter

Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed between January and April 2014 in the western English Channel. Sequencing of the heterocyst differentiation (hetR) and 16S rRNA genes placed this community within the Clade IV Trichodesmium, an understudied clade previously found only in low numbers in warmer waters. Nitrogen fixation...

A major Calanus finmarchicus overwintering population inside a deep fjord in northern Norway: implications for cod larvae recruitment success

High Calanus finmarchicus abundances were recorded in wintertime in Vestfjorden, close to the main cod breeding grounds off Lofoten and Vesterålen, northern Norway. The mean abundance for locations with water depth >500 m was ∼37000 ind. m−2 (range: 26700–49000 ind. m−2). To our knowledge, this is the first report of massive overwintering of C. finmarchicus on the Norwegian shelf...

Effects of climate variability on cladoceran zooplankton and cyanobacteria in a shallow subtropical lake

In peninsular Florida, USA, rainfall is coupled with the Pacific Sea Surface Temperature Anomaly (SSTA), and rainfall affects mean depth and residence time of shallow lakes. We examined effects of two cycles of variation in rainfall using a 15-year data set from a shallow eutrophic lake dominated by small zooplankton, cyanobacteria and omnivorous fish. In high rainfall periods...

Unexpected prevalence of parasite 18S rDNA sequences in winter among Antarctic marine protists

Parasites are not typically considered to be important components of polar marine ecosystems. It was therefore surprising when 18S rDNA surveys of protists in the West Antarctic Peninsula in winter revealed high abundances of parasite sequences. Parasite sequences made up, on average, over half (52%) of sequence reads in samples from deep water in winter. Winter surface water and...

Metabarcoding of marine zooplankton: prospects, progress and pitfalls

Metabarcoding (large-scale taxonomic identification of complex samples via analysis of one or few orthologous DNA regions, called barcodes) is revolutionizing analysis of biodiversity of marine zooplankton assemblages. Metabarcoding relies on high-throughput DNA sequencing (HTS) technologies, which yield millions of DNA sequences in parallel and allow large-scale analysis of...

Identifying copepod functional groups from species functional traits

We gathered information on the functional traits of the most representative copepod species in the Mediterranean Sea. Our database includes 191 species described by 7 traits encompassing diverse ecological functions: minimal and maximal body length, trophic group, feeding type, spawning strategy, diel vertical migration and vertical habitat. Cluster analysis in the functional...

Behavioral responses of freshwater calanoid copepods to the presence of ultraviolet radiation: avoidance and attraction

Binary choice experiments under natural solar radiation were used to test short-term behavioral responses of freshwater calanoid copepods to ultraviolet radiation (UV). Responses of the nine species from 15 populations spanning North and South America included both UV attraction and UV avoidance, and varied among habitats, species and populations. Copepods from more transparent...

Large biomass of small feeders: ciliates may dominate herbivory in eutrophic lakes

The importance of ciliates as herbivores and in biogeochemical cycles is increasingly recognized. An opportunity to observe the potential consequences of zooplankton dominated by ciliates arose when winter fish kills resulted in strong suppression of crustaceans by young planktivorous fish in two shallow lakes. On an annual average, ciliates made up 38–76% of the total...

UV radiation changes algal stoichiometry but does not have cascading effects on a marine food chain

Ultraviolet (UV)-B levels are still increasing at high and polar latitudes where ozone depletion continues. Changes in the quality of algae at the base of the food web can have a cascading effect on higher trophic levels. We examined whether UV radiation altered the synthesis of fatty acids (FA) and mycosporine-like amino acids (MAAs), as well as the C:N elemental stoichiometry...

Is chain length in phytoplankton regulated to evade predation?

Formation of cell chains in phytoplankton is ecologically important, but no single factor driving the evolution of chain formation has been identified. Chain length in the diatom Skeletonema marinoi declines in response to grazer cues, which reduces grazing losses in simple laboratory incubations. Here we explore a more ecologically relevant scenario with fluctuating populations...

Thalassorheology, organic matter and plankton: towards a more viscous approach in plankton ecology

Rheology is the study of how materials deform, particularly those materials not conforming to ideal solid or ideal liquid models. This is the case for much ocean water, due largely to the presence of organic exopolymeric substances, including mucilage, derived mostly from phytoplankton and bacterioplankton. This material makes the water more viscous and gives it elasticity...

Autumnal bottom-up and top-down impacts of Cyanea capillata: a mesocosm study

Jellyfish are effective predators on mesozooplankton and release large amounts of dissolved organic matter. Nevertheless, jellyfish initiated trophic cascades and bottom-up influences impacting lower trophic levels have received limited attention. We conducted a mesocosm experiment to quantify simultaneous top-down and bottom-up effects of a common jellyfish, Cyanea capillata, in...

What are jellyfish really eating to support high ecophysiological condition?

The feeding ecology of Blackfordia virginica was evaluated concurrently with their ecophysiological condition in a temperate estuary. The diet of B. virginica is composed not only of metazooplankton, as commonly observed for other jellyfish species, but also of phytoplankton, ciliates and detritus. This feeding behavior might explain their good nutritional condition and...

Pelagic population dynamics of Aurelia sp. in French Mediterranean lagoons

The pelagic dynamics of the cosmopolitan scyphozoan Aurelia sp. was investigated in three French Mediterranean lagoons, Thau, Berre and Bages-Sigean, which harbour resident populations. The annual cycles showed a common univoltine pattern in all lagoons where the presence of pelagic stages in the water column lasted ∼8 months. Field observations showed a release of ephyrae in...

Reproduction rates under variable food conditions and starvation in Mnemiopsis leidyi: significance for the invasion success of a ctenophore

The ctenophore Mnemiopsis leidyi is characterized by high growth rates and a large reproductive capacity. However, reproductive dynamics are not yet well understood. Here, we present laboratory data on food-dependent egg production in M. leidyi and egg hatching time and success. Further, we report on the reproduction of laboratory-reared and field-caught animals during starvation...

Feeding and starvation in the native ctenophore Bolinopsis infundibulum and the introduced Mnemiopsis leidyi in the North Sea: implications for ctenophore transport in ships' ballast water

Two lobate ctenophores, Bolinopsis infundibulum and Mnemiopsis leidyi, occur in the North Sea. Stomach contents of field-collected B. infundibulum were recorded and clearance rates for cladocerans and copepods calculated. In starvation experiments, daily body carbon losses of 2.2 and 1.2% and total carbon content losses of 76 and 63% were observed for B. infundibulum (after 68...