Michael N. Dawson

We present a genome assembly from a specimen of Pseudorhiza aurosa (Cnidaria; Scyphozoa; Rhizostomeae; Lychnorhizidae). The genome sequence has a total length of 183.49 megabases. The whole assembly is scaffolded into 18 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 13.73 kilobases. From the metagenome data, we recovered two high-quality metagenome-assembled genomes (MAGs).

We present a genome assembly from a specimen of Anthopleura xanthogrammica (giant green anemone; Cnidaria; Anthozoa; Actiniaria; Actiniidae). The genome sequence has a total length of 290.04 megabases. Most of the assembly (97.36%) is scaffolded into 19 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 20.04 kilobases. Gene annotation of this assembly by Ensembl identified 25,034 protein-coding genes.

We present a genome assembly from a specimen of Pelagia noctiluca (Mauve Stinger; Cnidaria; Scyphozoa; Semaeostomeae; Pelagiidae). The genome sequence has a total length of 357.08 megabases. Most of the assembly (94.91%) is scaffolded into 21 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 16.7 kilobases. Gene annotation of this assembly by Ensembl identified 19 573 protein-coding genes.

Insular aquatic habitats have the potential to expand upon current theory by providing alterna/tive perspectives on island biogeographical processes. Here, we investigate whether marine lakes—seawater surrounded by land—show patterns expected for ‘complete’ (e.g., ‘true’ oceanic islands) or ‘habitat’ islands using species, phylogenetic, and functional diversity of fishes. We surveyed 22 locations across three location types: stratified lakes and mixed lakes (i.e., islands) and ocean (i.e., mainland). Stratified lake communities were depauperate in species, and distinct in the proportion of traits related to colonization, environmental persistence, and niche competition; they are akin to ‘complete’ islands. Mixed lake communities had higher species richness and redundancy in traits when compared to stratified lake communities, and substantial turnover in beta diversity of species, lineages, and traits when compared to the mainland ocean communities; they are akin to ‘habitat’ islands. While two categories of marine lakes—stratified and mixed—were defined a priori based on physical structure and roughly correspond to ‘complete’ and ‘habitat’ islands, communities indicate variation within, and possibly a gradation between location types, including overlapping confidence intervals and outlier cases along primary axes of variation. Such gradation in marine lakes may be attributable to the youth and small size of these marine islands (2 ) relative to the ‘complete’ islands common to island biogeography theory (predominantly > 1 my and > 1 km ² ). Marine islands, therefore, may be defined from a biophysical perspective of communities as providing an emerging perspective with the potential to elucidate the community assembly of young islands generally. Fish communities in stratified lakes are distinguished from mixed lakes and ocean communities by their species, phylogenetic, and functional diversity. Stratified lake communities share attributes of ‘true’ oceanic islands, such as being geographically isolated, species-poor, and potential hotspots of endemism, in contrast to mixed lake communities that exhibit similarities with ‘habitat’ islands, having high connectivity, being relatively species-rich, lacking endemicity, and having trait redundancy. Stratified lakes do not share relationships with area and age as in mature and large islands; instead, they may illustrate the dynamics of small and young islands. Island biogeography theory is relevant beyond classical terrestrial island types; by applying the theory to marine systems, we can better explore the processes shaping young island communities, which are historically understudied. An island may be identified best by how organisms experience and respond to the geographical and environmental conditions.

We present a genome assembly from a specimen of Nausithoe racemosa (coronate scyphozoan jellyfish; Cnidaria; Scyphozoa; Coronatae; Nausithoidae). The assembly contains two haplotypes with total lengths of 4 784.66 megabases and 4 868.20 megabases. Most of haplotype 1 (97.34%) is scaffolded into 20 chromosomal pseudomolecules. Haplotype 2 was assembled to scaffold level. The mitochondrial genome has also been assembled, with a length of 13.97 kilobases. From the metagenome data, we recovered one high-quality metagenome-assembled genome.

We present a genome assembly from an individual Aurelia sp. 4 Dawson et al ., 2005 (moon jellyfish; Cnidaria; Scyphozoa; Semaeostomeae; Ulmaridae). The genome sequence has a total length of 462.10 megabases. Most of the assembly (99.99%) is scaffolded into 21 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 16.88 kilobases. From the metagenome data, we recovered 3 bins, of which 2 were high-quality MAGs.

We present a genome assembly from an individual Aurelia sp. 3 sensu Dawson et al . (2005) (scyphozoan jellyfish; Cnidaria; Scyphozoa; Semaeostomeae; Ulmaridae). The genome sequence has a total length of 512.46 megabases. Most of the assembly (98.35%) is scaffolded into 22 chromosomal pseudomolecules. The mitochondrial genome has also been assembled, with a length of 16.64 kilobases.From the metagenome data, we recovered three bins, of which two were high-quality MAGs.

We present a genome assembly from a specimen of Catostylus mosaicus (blue blubber; Cnidaria; Scyphozoa; Rhizostomeae; Catostylidae). The genome sequence has a total length of 217.98 megabases. Most of the assembly (99.58%) is scaffolded into 21 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.3 kilobases in length. Gene annotation of this assembly on Ensembl identified 16,715 protein-coding genes. The binned metagenomes included Anaplasmataceae bacterium, Rhodococcus qingshengii and a high-quality Gammaproteobacteria bacterium metagenome-assembled genome (MAG).

The rough limpet, Lottia scabra, a generalist grazer in the upper intertidal zone of the northeastern Pacific, spans the California Transition Zone, where southern warm-water populations gradually replace northern cold-water ones, providing a valuable system for studying genomic adaptation. We present the first high-quality reference genome for L. scabra, making a significant advancement over previously available molecular resources for both L. scabra and the genus Lottia. We used PacBio HiFi long reads and Omni-C chromatin proximity sequences to assemble a genome comprising 70 scaffolds spanning 414.08 Mb, with an N50 of 5.33 Mb and a completeness of 96.4% single-copy ortholog genes. The assembly contains 10 chromosome-scale scaffolds, consistent with previously published karyotypes of sister taxa. This high-quality genome will enhance our understanding of the mechanisms underlying adaptation to environmental differences and species responses to environmental change, with implications for coastal biodiversity conservation.