World Oceans Day 2020

Cresci et al. show that glass eels are able to use their magnetic compass to imprint the magnetic direction of tidal flows at the estuaries of the streams where they develop into yellow eels. The authors hypothesize that this ability helps glass eels to maintain their position in an estuary and to migrate upstream.

Vittoria Roncalli et al. used transcriptomics to study the acclimatization of a pre-adult copepod to the highly variable environment of the northern Gulf of Alaska. They find differences in expression of metabolic genes, particularly those involved in lipid metabolism, in different regions of the Gulf.

Subhajit Basu et al. provide evidence for mutualistic interactions between the nitrogen-fixing marine cyanobacteria Trichodesmium and associated bacteria in using iron from dust. Adding siderophores increases iron oxide dissolution and iron uptake, benefiting both Trichodesmium and the associated bacteria.

Samuel Green, Rafael Duarte et al. use models of fish vision to quantify camouflage in green and red chameleon prawns against seaweed backgrounds. They find that while color change occurs over longer periods of time, prawns modify their behaviour in the short term to select color-matching backgrounds.

Rowan Whittle et al. present fossil evidence of new isocrinid (sea lily) species from Antarctica and Australia. They show that isocrinid migration from shallow to deep water occurred at different times across the globe, spanning the Cretaceous-Paleogene to the Eocene/Oligocene.

Broman, Bonaglia et al. report a large-scale study of the micrometazoan community in the oxygen-poor, sulfidic Baltic Sea dead zone that is the largest in the world. They find that animals including nematodes and zooplankton are adapted to survive in this sediment, suggesting dead zones may be important biological resources upon recovery.

Hettle et al. investigate the ability of marine Pseudoalteromonas sp. to metabolise carrageenan, a polysaccharide abundant in red algae. They isolate and characterise previously unstudied strains and find that the recently identified κ/ι-carrageenan specific polysaccharide utilization locus (CarPUL) is required for growth on carrageenan, and biochemically map out many of the steps.

Cheryl L Ames, Anna Klompen et al. describe cassiosomes, stinging cell structures in the mucus of the upside-down jellyfish Cassiopea xamachana. They show that these motile cell masses consist of an outer epithelial layer largely composed of nematocytes surrounding centralized clusters of endosymbiotic dinoflagellates.

Rui Zhang et al. demonstrate that reduced viral pressure decreases the diversity of deep-sea bacterioplankton in the western Pacific Ocean. This study suggests that viruses sustain a diverse microbial community in deep-sea environments.

Torres-Águila et al. report that embryo development of the appendicularian chordate Oikopleura dioica is affected by biotoxins released by phytoplankton blooms. This work shows that these biotoxins may impact marine food webs and that defensome genes of appendicularians could be used to monitor the genetic stress of natural populations.

Berge et al. find that the normal working-light from a ship impacts on the vertical distribution of macrozooplankton and pelagic fish communities around the ship at three stations during the Arctic Polar Night. These data suggest bias from such effects should be taken into account when performing surveys and stock assessments in the Arctic.

Martínez et al. use DNA metabarcoding and a phylogeny-based approach to demonstrate the effects of tourist access on meiofauna diversity of beaches in Asinara National Park. Their results show that tourist frequentation decreases meiofaunal diversity at the shallow “swash” zone, and can be used to inform tourist access and management of beaches.

Yael Rosenberg et al. examine the effect of artificial light at night on coral reef biological processes. They find that genes involved in regulating the cell cycle and cell growth are differentially expressed when corals are exposed to ecological light pollution.

Masami Fujiwara et al. investigate the prevalence and distribution of nearly 150 fish and marine invertebrate species along the Gulf of Mexico over 35 years. They find that the expansion of tropical species into this region due to climate-mediated factors is increasing species diversity.

Estelle. S. Kilias et al. show that chytrid fungi exhibiting swimming tales are primarily encountered at sites influenced by sea ice melt and that its representation positively correlates with sea ice-associated diatoms. This study predicts that chytrid representation within its Arctic communities may increase as ice retreats further.

Sasha Tetu et al. have examined the effects of plastic leachate exposure on the marine bacteria Prochlorococcus, the most abundant photosynthetic organism on Earth. They find plastic leachates impair growth, photosynthetic capacity and cause global changes in transcription.

Jessica Ericson et al. examine the viability of Antarctic krill when exposed to near-future levels of ocean acidification for one year. These lab-based simulations of future ocean acidification show that adult krill actively maintain their body acid-base balance, enhancing their resilience.

Ellegaard et al. discuss the potential for using ancient environmental DNA (eDNA), combined with resurrection ecology, to analyse trophic interactions and evolutionary adaptation to changing environments. Their Review suggests that these techniques will improve our ability to predict genetic and phenotypic adaptation to environmental stress.

Francisco Nascimento et al. present changes to meiobenthic community composition following disturbance of tropical seagrass meadows. They show that shading and simulated grazing have a major impact on the trophic structure of the nematode and polychaete communities of sediments in seagrass habitats

Avery Paxton et al. test the effects of artificial reefs on abundance and biomass of fish on the southeastern coast of the USA. They report that deep artificial reefs are associated with high numbers and biomasses of tropical and subtropical fishes, likely caused by an increase in prey availability on artificial reefs.

Rupert A. Collins et al. show that environmental DNA degrades faster in the inshore urban environment than the ocean-influenced offshore environment. This study suggests that environmental DNA can be reliably detected for two days, providing an optimal time window of high local fidelity.

Javidpour et al. use high-frequency field data, geochemical-isotopic analysis, and modeling of prey–predator dynamics of the comb jelly in the western Baltic Sea to show that adult comb jellies cannibalize their own larvae. This shift to cannibalism allows adults to build nutrient reserves for periods of prey scarcity and sheds light on the ability of this invasive species to thrive amidst environmental fluctuations.

Ian Salter et al. report a quantitative comparison of environmental DNA (eDNA) and demersal trawl surveys for detecting Atlantic cod in oceanic waters. Their results suggest that this approach could contribute to regional assessments of commercially important fish species.