Trait-based approaches advance ecological and evolutionary research because traits provide a strong link to an organism’s function and fitness. Trait-based research might lead to a deeper understanding of the functions of, and services provided by, ecosystems, thereby improving management, which is vital in the current era of rapid environmental change. Coral reef scientists have long collected trait data for corals; however, these are difficult to access and often under-utilized in addressing large-scale questions. We present the Coral Trait Database initiative that aims to bring together physiological, morphological, ecological, phylogenetic and biogeographic trait information into a single repository. The database houses species- and individual-level data from published field and experimental studies alongside contextual data that provide important framing for analyses. In this data descriptor, we release data for 56 traits for 1547 species, and present a collaborative platform on which other trait data are being actively federated. Our overall goal is for the Coral Trait Database to become an open-source, community-led data clearinghouse that accelerates coral reef research.

Understanding the diversity and functioning of Arctic sea ice ecosystems is vital to evaluate and predict the impact of current and future climate change. In the microscopic communities inhabiting the brine channels inside sea ice, nematodes often dominate numerically and act as bacterivores and herbivores. Despite nematodes great abundances and known ecological roles, molecular tools have not been applied to investigate their species diversity in sea ice. In an attempt to begin establishing a molecular baseline for species diversity of sea ice nematodes, we Sanger sequenced 74 specimens from four locations around Svalbard (European Arctic), using the 18S rRNA barcode. Currently available nucleotide reference databases are both underpopulated with representative marine nematode taxa and contain a substantial number of misidentified organisms. Together, these limitations inhibited the ability to identify marine specimens collected in this study with certainty. Nevertheless, our molecular data indicate the presence of two genera in sea ice on Svalbard—TheristusandHalomonhystera.While it is possible that the latter represents a novel ice nematode species, future studies, including morphometric analysis, are needed to verify our molecular findings. We leverage the assignment of molecular information to robustly identify nematodes and provide the first insight into the diversity of sea ice nematodes in the European Arctic. We advocate for an intensified cooperation between molecular and morphological taxonomists to expedite the establishment of baseline surveys that are required to predict biological consequences of the diminishing sea ice habitat in the future.

Coastal marine ecosystems are increasingly affected by rising temperatures, declining oxygen and other human-driven stressors, which can alter predator–prey interactions. In the Baltic Sea, native fish and invasive comb jellies interact within a changing physical environment, with outcomes likely impacted by their different hypoxia tolerances. We investigated whether the abundant, native three-spined stickleback (Gasterosteus aculeatus) feeds on larvae (~400 μm) of the invasive comb jelly Mnemiopsis leidyi. Experiments were conducted under normoxic (100% O2) and moderate hypoxic (30% O2) conditions. We here present the first evidence of fish predation on M. leidyi larvae. Oxygen conditions had a significant impact on feeding rates (P < 0.001) and hypoxia led to a 68% and 69% reduction in G. aculeatus feeding on M. leidyi and the copepod Acartia tonsa, respectively. Consequently, while sticklebacks can ingest M. leidyi larvae, even moderate hypoxia will reduce its predation pressure on M. leidyi larvae and moreover reduce its potential to compete with larger M. leidyi for the common copepod prey A. tonsa.