Prvi nalaz tupousne barakude Sphyraena chrysotaenia (Klunzinger, 1884) i indopacifičke vrste ježinca Diadema setosum (Leske, 1778) u morskom zaštićenom području otoka Zakintos, Jonsko more, Grčka

In 2021, three specimens of the Lessepsian yellowstripe barracuda Sphyraena chrysotaenia and eight specimens of the Indo-Pacific needle-spined sea urchin Diadema setosum were recorded along the coasts of Zakynthos Island, some within the Marine Protected Area.U 2021. godini, tri primjerka lesepsijske tupousne barakude Sphyraena chrysotaenia i osam primjeraka indo-pacifičke vrste ježinca Diadema setosum su pronađeni u području oko otoka Zakintos, neki unutar morskog zaštićenog područja

Protistan Communities Within the Galápagos Archipelago With an Emphasis on Micrograzers

The Galápagos Archipelago is a globally significant biodiversity hotspot. However, compared to the relatively well-known megafauna, the distribution and ecological significance of marine protists in this system are poorly understood. To gain an understanding of the protistan assemblages across trophic modes, an intensive oceanographic survey was conducted in the Galápagos Marine Reserve (GMR) in October of 2018. The Equatorial Undercurrent (EUC)-influenced region had higher chlorophyll-a (Chl-a) concentrations than those of the eastern regions of the archipelago, along with higher abundances of protistan grazers. Specifically, proportions of autotrophic and potentially mixotrophic dinoflagellates were higher in the EUC, whereas in the eastern regions, heterotrophic dinoflagellates and chlorophytes dominated. Taxonomic composition and biochemical indicators suggested proportions of micrograzers and their associated heterotrophic biomass was higher in the oligotrophic, low Chl-a regions in the east. We also report observations from a dinoflagellate bloom in the western archipelago, which was heavily influenced by upwelling of the EUC. The red tide-forming dinoflagellate Scrippsiella lachrymosa was highly detected through light microscopy and DNA amplicon sequencing. In addition, the heterotrophic dinoflagellate Polykrikos kofoidii was detected and, based on cell densities observed in this study and grazing rates obtained from the literature, estimated to potentially graze up to 62% of S. lachrymosa bloom population. Our findings thus provide new insights into the composition of micrograzers and their potential roles in structuring protistan communities in the Galápagos Archipelago

Trapped DNA fragments in marine sponge specimens unveil North Atlantic deep-sea fish diversity

Sponges pump water to filter feed and for diffusive oxygen uptake. In doing so, trace DNA fragments from a multitude of organisms living around them are trapped in their tissues. Here we show that the environmental DNA retrieved from archived marine sponge specimens can reconstruct the fish communities at the place of sampling and discriminate North Atlantic assemblages according to biogeographic region (from Western Greenland to Svalbard), depth habitat (80–1600 m), and even the level of protection in place. Given the cost associated with ocean biodiversity surveys, we argue that targeted and opportunistic sponge samples – as well as the specimens already stored in museums and other research collections – represent an invaluable trove of biodiversity information that can significantly extend the reach of ocean monitoring.The study was supported by Grant NE/T007028/1 (SpongeDNA) from the UK Natural Environment Research Council to S.M. and A.R. A.R. was also supported by grants RYC2018-024247-I and PID2019-105769GB-I00 from the Spanish Ministry of Science and Innovation, in the framework of both MCIN/AEI/10.13039/50110001103 and ‘FSE invierte en tu futuro’, and an intramural grant from CSIC (PIE-202030E006).Peer reviewe

Environmental DNA persistence and fish detection in captive sponges

Large and hyperdiverse marine ecosystems pose significant challenges to biodiversity monitoring. While environmental DNA (eDNA) promises to meet many of these challenges, recent studies suggested that sponges, as “natural samplers” of eDNA, could further streamline the workflow for detecting marine vertebrates. However, beyond pilot studies demonstrating the ability of sponges to capture eDNA, little is known about the dynamics of eDNA particles in sponge tissue, and the effectiveness of the latter compared to water samples. Here, we present the results of a controlled aquarium experiment to examine the persistence and detectability of eDNA captured by three encrusting sponge species and compare the sponge's eDNA capturing ability with established water filtration techniques. Our results indicate that sponges and water samples have highly similar detectability for fish of different sizes and abundances, but different sponge species exhibit considerable variance in performance. Interestingly, one sponge appeared to mirror the eDNA degradation profile of water samples, while another sponge retained eDNA throughout the experiment. A third sponge yielded virtually no DNA sequences at all. Overall, our study suggests that some sponges will be suitable as natural samplers, while others will introduce significant problems for laboratory processing. We suggest that an initial optimization phase will be required in any future studies aiming to employ sponges for biodiversity assessment. With time, factoring in technical and natural accessibility, it is expected that specific sponge taxa may become the “chosen” natural samplers in certain habitats and regions.This study was supported by grant NE/T007028/1 from the UK Natural Environment Research Council. A.R. was also supported by the Spanish Ministry of Science and Innovation grant (RYC2018-024247-I) and CSIC intramural grant (202030E006).Peer reviewe

Optimized DNA isolation from marine sponges for natural sampler DNA metabarcoding

Marine sponges have recently been recognized as natural samplers of environmental DNA (eDNA) due to their effective water filtration and their ubiquitous, sessile, and regenerative nature. However, laboratory workflows for metabarcoding of sponge tissue have not been optimized to ensure that these natural samplers achieve their full potential for community survey. We used a phased approach to investigate the influence of DNA isolation procedures on the biodiversity information recovered from sponges. In Phase 1, we compared three treatments of residual ethanol preservative in sponge tissue alongside five DNA extraction protocols. The results of Phase 1 informed which ethanol treatment and DNA extraction protocol should be used in Phase 2, where we assessed the effect of starting tissue mass on extraction success and whether homogenization of sponge tissue is required. Phase 1 results indicated that ethanol preservative may contain unique and/or additional biodiversity information to that present in sponge tissue, but blotting tissue dry generally recovered more taxa and generated more sequence reads from the wild sponge species. Tissue extraction protocols performed best in terms of DNA concentration, taxon richness, and proportional read counts, but the non-commercial tissue protocol was selected for Phase 2 due to cost-efficiency and greater recovery of target taxa. In Phase 2 overall, we found that homogenization may not be required for sponge tissue and more starting material does not necessarily improve taxon detection. These results combined provide an optimized DNA isolation procedure for sponges to enhance marine biodiversity assessment using natural sampler DNA metabarcoding.This study was funded by the UK Natural Environment Research Council grant NE/T007028/1. A.R. was also supported by the Spanish Ministry of Science and Innovation grant (RYC2018-024247-I) and CSIC intramural grant (202030E006). M.B.A. was supported by the National Agency for Research and Development (ANID), fellowship program Postdoctorado en el extranjero/2019-74200143.Peer reviewe

Little samplers, big fleet: eDNA metabarcoding from commercial trawlers enhances ocean monitoring

The global need to monitor the status of marine resources is a priority task in marine management, but most ocean surveys still rely on costly and time-consuming capture-based techniques. Here we test a novel, easy-to use device to collect eDNA on board of bottom trawl fishing vessels, during normal fishing operations, quickly and easily: custom-made rolls of gauze tied to a hollow perforated spherical probe (the ‘metaprobe’) that placed inside the fishing net aims to gather traces of genetic material from the surrounding environment. We collected six samples from three central Tyrrhenian sites. Using an established fish-specific metabarcoding marker, we recovered over 70% of the caught species and accurately reconstructed fish assemblages typical of the different bathymetric layers considered. eDNA metabarcoding data also returned a biodiversity ‘bonus’ of mostly meso- pelagic species, not catchable by bottom trawls. Further investigation is needed to upscale this promising approach as a powerful tool to monitor catch composition, assess the distribution of stocks, and generally record changes in fish communities across the oceans