Search Results (10)

During a taxonomic revision on Caridina of East and Southeast Asia, a group of amphidromous and anchialine Caridina species, i.e., Caridina serratirostris, C. celebensis, C. rubella, C. troglodytes, C. magnovis, C. rintelenorum, and C. henriettae, widely distributed in the Indo-Pacific region has been found to exhibit distinct and unique morphological characters, e.g., rostra moderately long and straight, armed with many dorsal teeth, at least six of them on the carapace; telson terminating in a posteromedian projection; stylocerite long, reaching to or beyond the end of the basal segment of the antennular peduncle; and preanal carina with a spine, and with slender walking legs. Genetically, the group forms a monophyletic clade, either alone or together with the genus Marosina. The clade is well-separated from other species/species groups of Caridina. By taking a conservative taxonomic approach, the genus Marosina is thus redefined to accommodate members of the C. serratirostris species group. The revised genus Marosina can be separated from the typical Caridina species (represented by Caridina typus species group) by the structure of the endopod of the male first pleopod, which does not have an appendix interna, and the long stylocerite, which reaches to or beyond the end of the basal segment of the antennular peduncle, and the high number of postorbital teeth on the carapace. The paper provides a revised diagnosis of Marosina, with a key to all species assigned to it. Diagnosis, taxonomic remarks, habitat, and distribution information for all species are provided. The ecology, biogeography, and conservation of the genus are briefly discussed. Full article

Biodiversity patterns provide insights into the conservation value of ecosystems and also aid in an understanding of some research priorities. This research paper presents an exhaustive inventory of crustaceans and fish species from the Yucatan Peninsula’s epicontinental, underground, and anchialine aquatic systems. Using records spanning from 1936 to 2024, this study analyzed over 2600 entries across 670 aquatic systems, including cenotes, flooded cave lakes, springs, and wetlands. A total of 329 species were recorded, comprising 117 fish and 212 crustacean species. The richness and endemism of these species were assessed through a completeness analysis, utilizing non-parametric models (Chao 2, Jackknife 1, Bootstrap) to estimate potential species richness. Notably, the region exhibits high endemism, especially among crustaceans, with up to 50 species and 2 endemic families being unique to the Yucatan Peninsula. This study underscores the importance of the eastern YP for crustaceans and the central YP for fish, highlighting areas critical for conservation. These findings emphasize the need for further exploration, as the diversity of aquatic species remains incompletely understood. This comprehensive synthesis aims to inform future conservation strategies, environmental management, and regional planning efforts, particularly highlighting the vulnerability of these unique aquatic systems to environmental degradation. Full article

Within Polynoidae, a diverse aphroditiform family, the subfamily Macellicephalinae comprises anchialine cave-dwelling and deep-sea scaleworms. In this study, Lepidonotopodinae is synonymized with Macellicephalinae, and the tribe Lepidonotopodini is applied to a well-supported clade inhabiting deep-sea chemosynthetic-based ecosystems. Newly sequenced “genome skimming” data for 30 deep-sea polynoids and the comparatively shallow living Eulagisca gigantea is used to bioinformatically assemble their mitogenomes. When analyzed with existing scaleworm mitogenomes, deep-sea scaleworms exhibit increased gene order rearrangement events compared to shallow-water relatives. Additionally, comparative analyses of shallow-water vs. deep-sea polynoid substitution rates in mitochondrial protein-coding genes show an overall relaxed purifying selection and a positive selection of several amino acid sites in deep-sea species, indicating that polynoid mitogenomes have undergone selective pressure to evolve metabolic adaptations suited to deep-sea environments. Furthermore, the inclusion of skimming data for already known Lepidonotopodini species allowed for an increased coverage of DNA data and a representation of the taxa necessary to create a more robust phylogeny using 18 genes, as opposed to the six genes previously used. The phylogenetic results support the erection of Cladopolynoe gen. nov., Mamiwata gen. nov., Photinopolynoe gen. nov., Stratigos gen. nov., and Themis gen. nov., and emended diagnoses for Branchinotogluma, Branchipolynoe, Lepidonotopodium, and Levensteiniella. Full article

“El Aerolito” is the most biodiverse cenote cave globally, home to Poecilia velifera and Gambusia yucatana. However, their trophic niches and interactions remain undescribed. A total of 53 P. velifera and 38 G. yucatana were analyzed for stable isotopes, along with water samples for chlorophyll, silicates, and physical–chemical parameters. Data were collected during the norths, rainy, and dry seasons in the year 2023. Isotopic niches were calculated, and a PCA analysis was used to assess environmental factors. P. velifera showed δ¹³C values of −25.4‰, −25.7‰, and −24.5‰, whereas G. yucatana exhibited −24.8‰, −24.0‰, and −24.2‰ across seasons. Niche size varied, with the largest during the norths and smallest during the rainy season, indicating seasonality. PCA linked environmental parameters (e.g., temperature and dissolved oxygen) to resource availability, suggesting niche shifts due to rainfall. Mangroves and insects contributed to the isotopic signals, with shifts observed during the dry and rainy seasons. The highest water parameter values occurred during the dry and rainy seasons, while the lowest was during the norths. The system, nutrient-poor and lacking chlorophyll production, relies on external sources. The study concludes that isotopic niches are dynamic and seasonally influenced by abiotic factors, especially rainfall. Full article

Tropical marine lakes are small land-locked marine waterbodies occurring in karstic coastal areas. During biodiversity surveys in 12 marine lakes in Raja Ampat, Southwest Papua province, Indonesia, we recorded at least 37 species belonging to 29 genera of hard corals. Their observed associated symbiont fauna consisted of bivalve molluscs and polychaete worms. Marine lake temperature ranged from 30.0 to 32.5 °C, acidity from pH 7.6 to 8.1, and salinity from 26.4 to 33.2 ppt. This study provides the first inventory of the marginal coral communities in the extreme habitat of marine lakes, under chronic extreme environmental conditions of higher temperatures, land-based nutrient loads, and sedimentation. Full article

Marine and anchialine caves host specialized faunal communities with a variable degree of endemism and functional specialization. However, biodiversity assessments on this habitat are scarce, particularly in relation to small-sized cryptic fauna (such as amphipods), which often play a key role in benthic ecosystems. The present article compiles all records of marine and brackish-water amphipods inhabiting marine and anchialine caves along the Mediterranean basin, combining information extracted from a literature review with newly acquired records. A total of 106 amphipod species has been reported (representing approximately 20% of the Mediterranean amphipod species), mostly from the North-Western Mediterranean. Examination of new material from marine caves in Greece has yielded 14 new records from the East Ionian and Aegean Sea. Most of the reported species display wide ecological amplitude in terms of habitat and substrate preferences, feeding habits as well as bathymetric and geographical distribution. In contrast, only 17 amphipod species have been reported from marine-brackish waters in anchialine caves, predominantly represented by cave specialists with a narrow spatial distribution and distinct morphological traits. Our overall knowledge on amphipods inhabiting Mediterranean caves is far from complete so that new and valuable findings are expected to occur as new caves are explored. Full article

Staphylococcus aureus are human facultative pathogenic bacteria and can be found as contaminants in the environment. The aim of our study was to determine whether methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolated from coastal beach and river waters, anchialine pools, sand, and wastewater on the island of Hawaiʻi, Hawaiʻi, are a potential health risk. Samples were collected from three regions on Hawaiʻi Island from July to December 2020 during the COVID-19 pandemic and were characterized using whole-genome sequencing (WGS). From WGS data, multilocus sequence typing (MLST), SCCmec type, antimicrobial resistance genes, virulence factors, and plasmids were identified. Of the 361 samples, 98.1% were positive for Staphylococcus spp. and 7.2% were S. aureus positive (n = 26); nine MRSA and 27 MSSA strains were characterized; multiple isolates were chosen from the same sample in two sand and seven coastal beach water samples. The nine MRSA isolates were multi-drug resistant (6–9 genes) sequence type (ST) 8, clonal complex (CC) 8, SCCmec type IVa (USA300 clone), and were clonally related (0–16 SNP differences), and carried 16–19 virulence factors. The 27 MSSA isolates were grouped into eight CCs and 12 STs. Seventy-eight percent of the MSSA isolates carried 1–5 different antibiotic resistance genes and carried 5–19 virulence factors. We found S. aureus in coastal beach and river waters, anchialine pools, and sand at locations with limited human activity on the island of Hawaiʻi. This may be a public health hazard. Full article

Bermuda is an Eocene age volcanic island in the western North Atlantic, entirely capped by Pleistocene eolian limestone. The oldest and most highly karstified limestone is a 2 km² outcrop of the Walsingham Formation containing most of the island’s 150+ caves. Extensive networks of submerged cave passageways, flooded by saltwater, extend under the island. In the early 1980s, cave divers initially discovered an exceptionally rich and diverse anchialine community inhabiting deeper sections of the caves. The fauna inhabiting caves in the Walsingham Tract consists of 78 described species of cave-dwelling invertebrates, including 63 stygobionts and 15 stygophiles. Thus, it represents one of the world’s top hotspots of subterranean biodiversity. Of the anchialine fauna, 65 of the 78 species are endemic to Bermuda, while 66 of the 78 are crustaceans. The majority of the cave species are limited in their distribution to just one or only a few adjacent caves. Due to Bermuda’s high population density, water pollution, construction, limestone quarries, and trash dumping produce severe pressures on cave fauna and groundwater health. Consequently, the IUCN Red List includes 25 of Bermuda’s stygobiont species as critically endangered. Full article

Anchialine sinkholes provide insight into coastal aquifer systems and coastal mixing processes. Aquifer microbial community function is usually inferred from hydrochemical information, but there are few direct studies of microbial communities in the Floridan Aquifer. Hospital Hole is a 43 m-deep stratified sinkhole under the Weeki Wachee River, FL, with three distinct brackish layers: a hypoxic layer, a chemocline and a sulfidic anoxic layer. Illumina sequencing and bioinformatic tools were used to reconstruct metabolic functions and interactions of microbial communities in each layer. Each layer appears to originate from different parts of the coastal mixing zone and has a distinct microbial community with unique functions, which are influenced by the respective hydrochemistry. Sulfide oxidation and nitrate reduction are the most abundant functions. Syntrophy between methane oxidizers, methanogens and sulfate reducers is present. Similarities between the hydrochemistry and potential connectivity of Hospital Hole and the Floridan Aquifer coastal mixing zone suggest that microbial communities of Hospital Hole could be a surrogate for the coastal mixing zone of the aquifer in the absence of direct studies. Understanding how groundwater microbial communities react to saltwater intrusion and nutrient flux will be useful in predicting how coastal aquifer regions might react to anthropogenic change. Full article

We report the first integrated proteomic and transcriptomic investigation of a crustacean venom. Remipede crustaceans are the venomous sister group of hexapods, and the venom glands of the remipede Xibalbanus tulumensis express a considerably more complex cocktail of proteins and peptides than previously thought. We identified 32 venom protein families, including 13 novel peptide families that we name xibalbins, four of which lack similarities to any known structural class. Our proteomic data confirm the presence in the venom of 19 of the 32 families. The most highly expressed venom components are serine peptidases, chitinase and six of the xibalbins. The xibalbins represent Inhibitory Cystine Knot peptides (ICK), a double ICK peptide, peptides with a putative Cystine-stabilized α-helix/β-sheet motif, a peptide similar to hairpin-like β-sheet forming antimicrobial peptides, two peptides related to different hormone families, and four peptides with unique structural motifs. Remipede venom components represent the full range of evolutionary recruitment frequencies, from families that have been recruited into many animal venoms (serine peptidases, ICKs), to those having a very narrow taxonomic range (double ICKs), to those unique for remipedes. We discuss the most highly expressed venom components to shed light on their possible functional significance in the predatory and defensive use of remipede venom, and to provide testable ideas for any future bioactivity studies. Full article