Predator-induced defense decreases growth rate and photoprotective capacity in a nitrogen-limited dinoflagellate, Alexandrium minutum.

Some dinoflagellates produce toxic secondary metabolites that correlate with increased resistance to grazers. The allocation costs of toxin production have been repeatedly addressed, but with conflicting results. Few studies have considered the potential costs of this defense to the photosystem, even though defense toxins (e.

Antarctic krill sequester similar amounts of carbon to key coastal blue carbon habitats.

The carbon sequestration potential of open-ocean pelagic ecosystems is vastly under-reported compared to coastal vegetation 'blue carbon' systems. Here we show that just a single pelagic harvested species, Antarctic krill, sequesters a similar amount of carbon through its sinking faecal pellets as marshes, mangroves and seagrass. Due to their massive population biomass, fast-sinking faecal pellets and the modest depths that pellets need to reach to achieve sequestration (mean is 381 m), Antarctic krill faecal pellets sequester 20 MtC per productive season (spring to early Autumn).

A siliceous arms race in pelagic plankton.

Coevolution between predator and prey plays a central role in shaping the pelagic realm and may have significant implications for marine ecosystems and nutrient cycling dynamics. The siliceous diatom frustule is often assumed to have coevolved with the silica-lined teeth of copepods, but empirical evidence of how this relationship drives natural selection and evolution is still lacking. Here, we show that feeding on diatoms causes significant wear and tear on copepod teeth and that this leads to copepods becoming selective feeders.

Organismal trade-offs and the pace of planktonic life.

No one is perfect, and organisms that perform well in some habitat or with respect to some tasks, do so at the cost of performance in others: there are inescapable trade-offs. Organismal trade-offs govern the structure and function of ecosystems and attempts to demonstrate and quantify trade-offs have therefore been an important goal for ecologists. In addition, trade-offs are a key component in trait-based ecosystem models.

Foraging mechanisms in excavate flagellates shed light on the functional ecology of early eukaryotes.

The phagotrophic flagellates described as "typical excavates" have been hypothesized to be morphologically similar to the Last Eukaryotic Common Ancestor and understanding the functional ecology of excavates may therefore help shed light on the ecology of these early eukaryotes. Typical excavates are characterized by a posterior flagellum equipped with a vane that beats in a ventral groove. Here, we combined flow visualization and observations of prey capture in representatives of the three clades of excavates with computational fluid dynamic modeling, to understand the functional significance of this cell architecture.

Cross-basin and cross-taxa patterns of marine community tropicalization and deborealization in warming European seas.

Ocean warming and acidification, decreases in dissolved oxygen concentrations, and changes in primary production are causing an unprecedented global redistribution of marine life. The identification of underlying ecological processes underpinning marine species turnover, particularly the prevalence of increases of warm-water species or declines of cold-water species, has been recently debated in the context of ocean warming. Here, we track changes in the mean thermal affinity of marine communities across European seas by calculating the Community Temperature Index for 65 biodiversity time series collected over four decades and containing 1,817 species from different communities (zooplankton, coastal benthos, pelagic and demersal invertebrates and fish).

Responses of intraspecific metabolic scaling to temperature and activity differ between water- and air-breathing ectothermic vertebrates.

Metabolism underpins all life-sustaining processes and varies profoundly with body size, temperature and locomotor activity. A current theory explains some of the size-dependence of metabolic rate (its mass exponent, b) through changes in metabolic level (L). We propose two predictive advances that: (a) combine the above theory with the evolved avoidance of oxygen limitation in water-breathers experiencing warming, and (b) quantify the overall magnitude of combined temperatures and degrees of locomotion on metabolic scaling across air- and water-breathers.

The fluid dynamics of barnacle feeding.

Sessile barnacles feed by sweeping their basket-like cirral fan through the water, intercepting suspended prey. A primary component of the diet of adult barnacles is copepods that are sensitive to fluid disturbances and capable of escaping. How do barnacles manage to capture copepods despite the fluid disturbances they generate? We examined this question by describing the feeding current architecture of 1 cm sized Balanus crenatus using particle image velocimetry, and by studying the trajectories of captured copepods and the escapes of evading copepods.

The function of the feeding groove of 'typical excavate' flagellates.

Phagotrophic flagellates are the main consumers of bacteria and picophytoplankton. Despite their ecological significance in the 'microbial loop', many of their predation mechanisms remain unclear. 'Typical excavates' bear a ventral groove, where prey is captured for ingestion.

A trait-based approach to assess niche overlap and functional distinctiveness between non-indigenous and native species.

Our understanding of the community assembly processes acting on non-indigenous species (NIS), as well as the relationship with native species is limited, especially in marine ecosystems. To overcome this knowledge gap we here develop a trait-based approach based on the functional distinctiveness metric to assess niche overlap between NIS and native species, using high-resolution data on benthic invertebrate communities in the Baltic Sea. Our results show that NIS retain a certain degree of similarity with native species, but display one or a few singular unique traits (e.

Predation in a Microbial World: Mechanisms and Trade-Offs of Flagellate Foraging.

Heterotrophic nanoflagellates are the main consumers of bacteria and picophytoplankton in the ocean and thus play a key role in ocean biogeochemistry. They are found in all major branches of the eukaryotic tree of life but are united by all being equipped with one or a few flagella that they use to generate a feeding current. These microbial predators are faced with the challenges that viscosity at this small scale impedes predator-prey contact and that their foraging activity disturbs the ambient water and thus attracts their own flow-sensing predators.

Boldness and physiological variation in round goby populations along their Baltic Sea invasion front.

The round goby (Neogobius melanostomus) is a fish native to the Ponto-Caspian region that is highly invasive through freshwater and brackish habitats in northern Europe and North America. Individual behavioural variation appears to be an important factor in their spread, for example a round goby's personality traits can influence their dispersal tendency, which may also produce variation in the behavioral composition of populations at different points along their invasion fronts. To further analyze the drivers of behavioral variation within invasive round goby populations, we focused on two populations along the Baltic Sea invasion front with closely comparable physical and community characteristics.

Gelatinous larvacean zooplankton can enhance trophic transfer and carbon sequestration.

Larvaceans are gelatinous zooplankton abundant throughout the ocean. Larvaceans have been overlooked in research because they are difficult to collect and are perceived as being unimportant in biogeochemical cycles and food-webs. We synthesise evidence that their unique biology enables larvaceans to transfer more carbon to higher trophic levels and deeper into the ocean than is commonly appreciated.

Negative and positive interspecific interactions involving jellyfish polyps in marine sessile communities.

Sessile marine invertebrates on hard substrates are one of the two canonical examples of communities structured by competition, but some aspects of their dynamics remain poorly understood. Jellyfish polyps are an important but under-studied component of these communities. We determined how jellyfish polyps interact with their potential competitors in sessile marine hard-substrate communities, using a combination of experiments and modelling.

Rapid upwards spread of non-native plants in mountains across continents.

High-elevation ecosystems are among the few ecosystems worldwide that are not yet heavily invaded by non-native plants. This is expected to change as species expand their range limits upwards to fill their climatic niches and respond to ongoing anthropogenic disturbances. Yet, whether and how quickly these changes are happening has only been assessed in a few isolated cases.

Mapping intertidal macrophytes in fjords in Southwest Greenland using Sentinel-2 imagery.

Changes in the distribution of coastal macrophytes in Greenland, and elsewhere in the Arctic are difficult to quantify as the region remains challenging to access and monitor. Satellite imagery, in particular Sentinel-2 (S2), may enable large-scale monitoring of coastal areas in Greenland but its use is impacted by the optically complex environments and the scarcity of supporting data in the region. Additionally, the canopies of the dominant macrophyte species in Greenland do not extend to the sea surface, limiting the use of indices that exploit the reflection of near-infrared radiation by vegetation due to its absorption by seawater.

Seasonal variability of phytoplankton community response to thermal discharge from nuclear power plant in temperate coastal area.

Nuclear power plants (NPPs) developed rapidly worldwide in the last half-century and have become one of the most important electric power sources. Thermal discharge from NPPs increases the temperature of receiving waters, directly and indirectly affecting phytoplankton community. Seasonal and interannual variation in environmental factors in temperate areas makes it challenging to determine the effects of thermal effluents from NPPs on coastal phytoplankton.

Acoustic tethering of microorganisms.

We show how to construct and apply a setup to acoustically tether and enable behavioral observations of individual microorganisms using simple laboratory equipment and a standard light microscope. We explore the capability of the setup with the freely swimming dinoflagellate Alexandrium minutum as the study organism. The setup allows us to tether cells in focus in the mid-plane of the sample chamber and make observations of individual organisms at high magnification without affecting their flagellar beat frequencies.

Economic expenditures by recreational anglers in a recovering atlantic bluefin tuna fishery.

The recent return of Atlantic bluefin tuna to northern Europe following the recovery of the east Atlantic stock has sparked substantial public and scientific interest. This is particularly true for recreational anglers in Denmark, who often consider Atlantic bluefin tuna to be the catch of a lifetime. This attitude has previously sustained a substantial recreational fishery for bluefin tuna with annual tournaments in Denmark, which peaked in the 1950s before the subsequent collapse of the stock during the 1960s.

Evolution of toxins as a public good in phytoplankton.

Toxic phytoplankton blooms have increased in many waterbodies worldwide with well-known negative impacts on human health, fisheries and ecosystems. However, why and how phytoplankton evolved toxin production is still a puzzling question, given that the producer that pays the costs often shares the benefit with other competing algae and thus provides toxins as a 'public good' (e.g.

Costs and benefits of predator-induced defence in a toxic diatom.

Phytoplankton employ a variety of defence mechanisms against predation, including production of toxins. Domoic acid (DA) production by the diatom spp. is induced by the presence of predators and is considered to provide defence benefits, but the evidence is circumstantial.

The formation of avian montane diversity across barriers and along elevational gradients.

Tropical mountains harbor exceptional concentrations of Earth's biodiversity. In topographically complex landscapes, montane species typically inhabit multiple mountainous regions, but are absent in intervening lowland environments. Here we report a comparative analysis of genome-wide DNA polymorphism data for population pairs from eighteen Indo-Pacific bird species from the Moluccan islands of Buru and Seram and from across the island of New Guinea.

Disentangling tropicalization and deborealization in marine ecosystems under climate change.

As climate change accelerates, species are shifting poleward and subtropical and tropical species are colonizing temperate environments. A popular approach for characterizing such responses is the community temperature index (CTI), which tracks the mean thermal affinity of a community. Studies in marine, freshwater, and terrestrial ecosystems have documented increasing CTI under global warming.