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A new species of the dinoflagellate genus Bysmatrum was isolated from tidal pool samples originating from Cape Peninsula, South Africa. This new species was investigated by light, scanning and transmission electron microscopy, and its phylogenetic affinities were analyzed using molecular data. Cells were pentagonal in ventral view, 25-45 μm long and 20-42.5 μm wide and only slightly flattened in a dorsiventral plane. The epitheca, in apical view, was almost circular, with a slight ventral depression. Plate tabulation (P O , X, 4′, 3a, 7″, 6c, 4s, 5′′′, 2′′′′) was typical for the genus Bysmatrum. Apical plate 1′ was heptagonal and broadly asymmetric, with an elongated, fingerlike extension at the base. The intercalary plates 2a and 3a were separated by a direct connection between plates 3′ and 4″. The thecal plates were perforated by pores of different sizes and ornamented with linearly arranged reticulations. Intercalary bands were smooth, and antapical plates were not indented. This new species differs from the five other known species of the genus Bysmatrum in morphology (e.g. the shape of apical plate 1′) and it occupies an isolated position in phylogenetic trees inferred by analyses of small-subunit ribosomal DNA (SSU-rDNA) sequence data. This also represents the first report of the SSU rDNA sequence for Bysmatrum arenicola.

The supratidal–intertidal sabkha of the Al-Kharrar area, Red Sea coast, Saudi Arabia, contains the evaporite minerals gypsum, anhydrite, and halite. Microbial mats flourish adjacent to the sabkha evaporites in tidal flats and pools of the Al Kharrar lagoon. Desiccation and decay of some microbial mats in tidal flat areas have led to precipitation of gypsum and halite there. The evaporite minerals have been precipitated through displacive, inclusive, and replacive growth within mud, sand, gravelly sand, and bioclastic sediment of the sabkha. Gypsum occurs as lenticular and tabular crystals whereas anhydrite occurs as nodular (individual, mosaic, and enterolithic) and pseudomorphs of lenticular gypsum crystals that grew displacively and replacively near the surface of the sabkha. Halite exists as a diagenetic cement within the sabkha sediment, or as primary rafts and skeletal crystals in desiccated tidal pools with salinity over 220‰. Microbial mats are growing on the surface of the upper tidal flat areas and in pools at a salinity range of 80–110‰, and they lead to biostabilization of the sediment. They have induced a range of sedimentary surface structures (MISS) including gas domes, reticulate patterns, tufts, pinnacles, wrinkles, and microbial shrinkage cracks. The occurrence, abundance, and association of evaporite minerals and MISS are controlled by local environmental factors such topography of the sabkha, emergence or submergence of tidal areas, surface area of the evaporite basin, contribution of meteoric water from floods from the adjoining Red Sea Mountains, and water salinity. These factors promote the growth of the microbial mats in the winter months, and deposition of evaporite minerals during summer months. Field and petrographic data indicate that the main recharge to the sabkha area is from tidal flow and water seepage from the Al-Kharrar lagoon. The results of this study indicate that within a small sabkha area of Al-Kharrar (3 × 17 km), a large variation in evaporite mineral types and morphologies grade into and are associated with MISS due to local environmental parameters. The interpretation of this association of evaporite minerals and MISS provides useful data for understanding the mechanisms responsible for precipitation of evaporite minerals and formation of MISS.

Rock pools are ephemeral freshwater habitats characterized by their small size, well-defined boundaries, and periodic desiccation, making them ideal model systems to answer numerous ecological questions. Although there are numerous studies on rock pool fauna around the world, tardigrades have only rarely been recorded. We conducted the first tardigrade-focused study on rock pools by quantitatively extracting and classifying them from rock pools in the Italian Apennines. Rock pools were divided into three types, based on maximum duration of their inundation period. Following the patterns usually observed with rock pool invertebrates, we tested the hypothesis that desiccation has a negative effect on prevalence, abundance, and diversity of tardigrades, and thus could alter the trophic structure of their communities. In contrast to what is commonly found for other animal groups in the same type of habitat, we found that tardigrades were more diverse and prevalent in shallower, more desiccation prone, rock pools. Moreover, the trophic structure of tardigrade communities was different among the different pool types. Lastly, we also provide DNA barcodes of the most commonly found taxa. Ultimately, our study demonstrates that tardigrade communities in rock pools provide a valuable model system for the study of abiotic factors influencing meiofauna communities.

Understanding how local conditions and dispersal dynamics structure communities of passively dispersing aquatic invertebrates remains uncertain, especially in aridland systems. In these systems, dispersal is irregular and successful colonization is subject to priority effects. To investigate these factors, we compared rotifer species composition from Chihuahuan Desert rock pools, playas, and tanks. (1) We found 132 species with high beta-dissimilarity among sites (> 0.8). (2) Correlation between species richness and habitat area was significant, but weak, for all sites. (3) Dissimilarity analyses, supported by negative Dispersal-Niche Continuum Index (DNCI) values, showed that stochastic processes dominate community assembly. (4) We examined influence of three important environmental variables on richness and community structure: hydroperiod, algal mat and macrophyte development, and conductivity; we also examined how rotifer trophi type (a functional trait) affected DNCI and identified indicator species. Hydroperiod was important for playas and tanks, but not rock pools. Conductivity had a strong influence. Richness was greatest in habitats with highest amounts of vegetation. Environmental factors explained ~12% of variation in community composition, indicating that while deterministic processes are significant, stochastic processes dominate in these systems. We provide a conceptual model that highlights the distinctive of nature aquatic communities in aridlands compared to temperate regions.

The diversity of symbiotic dinoflagellate Symbiodiniaceae hosted by anthozoans is known to be driven by the environment where the hosts are found. This study examined how environmental variations (<1 to 100s m) can influence the diversity of Symbiodiniaceae within the zoantharian Palythoa tuberculosa. We monitored the dominant Symbiodiniaceae lineages within tagged P. tuberculosa colonies near the Hija River mouth and adjacent coastal reefs at Mizu gama, Okinawa, Japan, between July 2016 and April 2018. Seven sites were chosen based on depth and distance from the river mouth, with 5 tagged colonies at each site. Water parameters of tidal pools (TPs) at the river mouth, especially temperature, were significantly different from other sites. Surprisingly, P. tuberculosa colonies at TPs were more resilient to bleaching during summers compared to colonies at other shallow sites. We observed different Cladocopium psbAncr lineages hosted by the tagged P. tuberculosa, with TPs colonies usually hosting one Cladocopium lineage (designated as lineage 4). Colonies from the deep sites and other shallow sites hosted mostly Cladocopium lineages 1 (generalist) and 2 (riverine specialist). Throughout the study period, the shallow colo nies (included TPs) recorded higher rates of switching dominant Cladocopium lineages (mostly to lineage 1), whereas most deep colonies did not switch their dominant Cladocopium lineages. Our results show that Cladocopium lineage 1, previously reported as a generalist lineage in terms of environmental parameters, could also be an opportunist lineage during periods of host stress. Our study confirms that Cladocopium lineage flexibility likely helps the resilience of P. tuberculosa in such variable environments.

Light availability and habitat complexity are two key drivers of community assembly. Urbanisation has been shown to affect both, with important consequences to ecological communities. On the intertidal, for instance, studies have shown that light intensity is greater on natural rocky shores than on less complex artificial habitats (seawalls), though different habitats can also experience similar light intensities, for example when shaded by urban structures. Understanding therefore how these factors individually, and combined, affect communities is important to understand the mechanisms driving changes in community structure, and consequently provide solutions to tackle the increasing homogenisation of habitats and lightscapes in urbanised spaces through smart infrastructure designs. Here, we assessed how different light levels affect the recruitment of communities in rock pools and on emergent rock on an intertidal rocky shore. We cleared 30 patches of emergent rock and 30 rock pools and manipulated light using shades with different light transmissions (full light, procedural control, 75%, 35%, and 15% light transmission, full shade) and assessed mobile and sessile communities monthly for 6 months. Effects of reducing light levels were generally stronger on rock than in pools. Fully shaded plots supported double the amount of mobile organisms than plots in full sunlight, in both habitats. Algal cover was higher in pools compared to rock, and at intermediate light levels, but effects varied with site. This study highlights the importance of variable light conditions and different habitats for rocky shore communities, which should be considered in future coastal developments to retain natural biodiversity.

Global warming threatens community stability and biodiversity around the globe. Knowledge of the mechanisms underlying the responses to rising temperatures depends heavily on generic food-web models that do not account for changes in network structure along latitudes and temperature gradients. Using 124 marine rock-pool food webs sampled across four continents, we show that despite substantial variation in ambient temperature (mean 11.5–28.4 °C), similar empirical food-web and body-mass structures emerge. We have used dynamic modelling to test whether communities from warmer regions are more sensitive to warming and found a general hump-shaped relationship between simulated biodiversity and temperature (gradient from 0–50 °C). This implies that an expected anthropogenic global warming of 4 °C should increase biodiversity in arctic to temperate regions while biodiversity in tropical regions should decrease. Interestingly, simulations of synthetic networks did not yield similar results, which stresses the importance of considering the specificities of natural food webs for predicting community responses to environmental changes.Global warming will affect food-web structure and species persistence, and real world data is needed for better prediction. Combining species counts and temperature data from rock pools with dynamic modelling predicts biodiversity increases in arctic to temperate regions and declines in the tropics.

Little is known of the macrobenthos supported within stingray feeding pits. Compared to adjacent unpitted areas during low tide, macrobenthic abundance and biodiversity within the stingray pits might be expected to be (i) greater , the water-retaining pits functioning like rock pools; (ii) no different , since macrofaunal recolonisation can occur very rapidly; or (iii) less , consequent on the substratum changes that typify depressions in soft sediments. In both (i) and (iii) differences in composition of the supported assemblages would be expected, though not in (ii). To differentiate between these alternative hypotheses, faunal characteristics within intertidal stingray pits were compared to those in the adjacent background sandflat in Moreton Bay, Queensland, where the prey of the rays are the decapod crustaceans Trypaea and Mictyris that otherwise structure the benthic system. Results generally (though not totally) support hypothesis (ii), it being consistently found that feeding pits supported less macrobenthic abundance than the surrounding sandflat but subequal taxon density, evenness and patchiness of their faunas, and their taxonomic compositions were very similar. Such feeding pits undoubtedly structure many intertidal sandflats and increase both their topographical complexity and their habitat diversity, but this is not reflected in increased macrobenthic biodiversity.

The analysis of a natural motor action is always difficult, especially when different motor programs are combined within the same interaction with the environment. We analyzed the behavior of an octopus, Abdopus sp., filmed in tidal pools in Okinawa, Japan, which used the kinematic primitives of rotation and translation of its hydrostatic arms, and combined these kinematic behaviors serially and in parallel to ‘slap’ at fish in the wild. In total, 19 slaps were analyzed. The kinematics of arm movement were measured in both external and animal-centered reference frames, while the octopus was slapping at the fish. By combining these primitives, the octopus is able to maintain flexibility while controlling only a few degrees of freedom, a concept we term ‘flexible rigidity’. This slapping action supports Flash and Hochner’s embodied organization view of motor behavior, as well as their idea that motor primitives can combine syntactically to form a complex action. The octopus’s ability to use sensory feedback from the position of a moving fish target, along with the feed-forward motor primitives, allows for the building of complex actions at dynamic equilibrium with the environment. Over all, these findings lead to a more realistic view of how a complex behavior allows an animal to coordinate with its environment.

Invasive organisms may cause ecologic, economic, and public health harm. Aedes japonicus is an invasive mosquito species of known ecologic and public health importance that has widely spread throughout the eastern USA since initially being recognized in Connecticut in 1998. Here, we report the known distributions of Ae. japonicus within the Great Smoky Mountains National Park (GSMNP) since its initial recognition in the park in 2004. From 2006 to 2022, we sampled eggs, larvae, and adult life stages through targeted, haphazard, and convenience collections. Through these efforts, we surveyed 23 (54.7%) of the 42 watersheds within the GSMNP. Aedes japonicus was present in 19 (82.6%) of the sampled watersheds, and the species was confirmed, in some instances, at the same location over multiple years, suggesting it remains entrenched. This species was observed in 45.2% of the GSMNP watersheds at elevations ranging from 347 to 1,478 m. Naturally occurring containers (i.e., riverine rock pools) were common collection sites in this study. The results of our findings are presented in the context of the species distribution within the park, the public health relevance given the GSMNP’s public visitation rate (>12 million annually), potential species interactions, and the persistence of this species over the multiyear study.