The rapid advancement of environmental DNA (eDNA) technology has transformed ecological research, particularly in aquatic ecosystems. However, the optimal sampling matrix (e.g., water or sediment) and the potential for eDNA to replace or complement traditional underwater visual census (UVC) remain unclear. Here, we integrate water eDNA, sediment eDNA, and UVC approaches to systematically compare the diversity of benthic macrofauna in the subtidal zones of the Nanji Islands, China. Our results show that sediment eDNA samples exhibited the highest species richness, while UVC had the lowest. Each method revealed distinct species profiles, with relatively few shared taxa at the order level and below. Environmental eDNA showed significant advantages in detecting key phyla such as Annelida and Arthropoda. In contrast, traditional UVC was crucial for identifying certain taxa, such as Bryozoa, which were undetectable by eDNA methods. The low overlap in species detected by these methods underscores their complementary nature, highlighting the necessity of integrating multiple approaches to achieve a more comprehensive and accurate biodiversity assessment. Future research should focus on refining eDNA techniques, such as developing more universal primers, to further enhance their applicability in biodiversity monitoring.

The depolymerized products and oligosaccharide fractions from sea cucumber fucosylated glycosaminoglycans (FGs) are promising anticoagulant candidates, and more novel FG-derived oligosaccharides from low-priced sea cucumbers are expected to be obtained. This study isolated 5−12 oligomers (OF1−OF3) with unusual branches from β-eliminative depolymerized products of Colochirus quadrangularis FG (CqFG). Detailed NMR analyses showed that OF1−OF3 consisted of a chondroitin 4,6-sulfates backbone and some sulfated fucosyl branches (FucS), including monosaccharides (α-l-Fuc_2S4S, α-l-Fuc_3S, α-l-Fuc_4S, α-l-Fuc_2S3S4S, and α-l-Fuc_2S) and a disaccharide D-Gal_3S4S-α1,3-l-Fuc_2S4S with the ratio of ~36:35:10:7:3:9, attached to the C-3 position of β-d-GlcA or its derivatives, such as α-l-Δ4,5GlcA and β-d-GlcA-ol. Unusually, α-l-Fuc_3S was the main FucS branch; no α-l-Fuc_3S4S branch was found, and α-l-Fuc_2S3S4S and α-l-Fuc_2S branches were also found in OF1–OF3. The OF2 and OF3 could strongly inhibit the intrinsic and common coagulation pathways. Intrinsic FXase is a target of OF2 and OF3 inhibiting the intrinsic coagulation pathways, and the unusual side chains may increase the intrinsic FXase inhibitory activity. OF2 and OF3 showed negligible bleeding risk, and less bleeding than heparin (HP), low-molecular-weight heparins (LMWHs), and CqFG. These findings support novel FG oligosaccharides with some unusual branches from low-priced sea cucumbers to be prepared as safer anticoagulants.

Azooxanthellate scleractinian corals, which lack symbiotic dinoflagellates, occur from shallow waters to deep-sea environments. In deep-sea benthic ecosyst

A new shallow-water gorgonian coral species in the family Acanthogorgiidae, Paraplexaura binyuani sp. nov., is described from a specimen collected at Huaguang Atoll in the South China Sea at a depth of 22 m. The new species is distinguished from its congeners by abundant polyp sclerites, predominantly flattened rods, and by the coenenchyme bearing numerous large spindles reaching up to 0.6 mm in length, which are approximately two to three times longer than those reported for most described species of Paraplexaura. Phylogenomic analyses based on ultraconserved elements (UCEs) recover Paraplexaura as monophyletic and place P. binyuani sp. nov. as sister to P. cryptotheca, consistent with its morphological distinctiveness and supporting its recognition as a separate species.

Recent phylogenomic studies have clarified many higher-level relationships within Octocorallia, but the generic boundaries of many acanthogorgiid-like taxa within Malacalcyonacea remain poorly defined. During shallow-water surveys along the coast of China, we collected three gorgonian colonies that could not be assigned confidently to any described genus on the basis of comparative morphology. Using an integrative approach combining colony, polyp, and sclerite morphology with ultraconserved element (UCE) phylogenomics, we recovered these specimens as a distinct lineage within Malacalcyonacea M8 Clade C, sister to the sampled Anthogorgia lineage comprising A. divaricata and A. ochracea with maximal support (SH-aLRT/UFBoot = 100/100). The new lineage is distinguished from its phylogenomic relatives by the following combination of characters: colony arborescent; polyps fully retractile in low conical calyces on all sides of the branches; anthocodial armature consisting of a collaret and points; calicular sclerites arranged in eight loose longitudinal bands; coenenchyme and calyces with warty or occasionally branched spindles, some blunt-ended. It differs morphologically from the most similar genus, Calicogorgia, in having calyces distributed on all sides of the branches (vs. laterally arranged) and calicular sclerites in eight loose longitudinal bands (vs. eight bands each composed of two distinct rows). We therefore establish Curvagorgia gen. nov. and describe Curvagorgia caerulea gen. et sp. nov. as the type species by monotypy.