Urban tourist beach ecosystems provide the essential service of recreation. These ecosystems also support critical ecological functions where biodiversity conservation is not usually a priority. The sudden lockdown due to the COVID-19 pandemic created a unique opportunity to evaluate the effects of human absence in these urbancoastal ecosystems. This study examined bioindicators from 29 urban tourist beaches in seven Latin-American countries and assesses their response to lockdown about some relevant anthropogenic stressors such as pollution, noise, human activities, and user density. The presence of animals and plants, as well as the intensity of stressors, were assessed through a standardized protocol during lockdown conditions. Additionally, the environmental conditions of the beaches before and during lockdown were qualitatively compared using multivariate non-parametric statistics. We found notable positive changes in biological components and a clear decrease in human stressors on almost all the beaches. Dune vegetation increased on most sites. Similarly, high burrow densities of ghost crabs were observed on beaches, except those where cleaning activity persisted. Because of the lockdown, there was an exceptionally low frequency of beach users, which in turn reduced litter, noise and unnatural odors. The observed patterns suggest that tourist beaches can be restored to natural settings relatively quickly. We propose several indicators to measure changes in beaches once lockdown is relaxed. Adequate conservation strategies will render the recreational service of tourist beaches more environmental-friendly.

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses.

SummaryThe essence of the generalised multivariate Behrens-Fisher problem (BFP) is how to test the null hypothesis of equality of mean vectors for two or more populations when their dispersion matrices differ. Solutions to the BFP usually assume variables are multivariate normal and do not handle high-dimensional data. In ecology, species' count data are often highdimensional, non-normal and heterogeneous. Also, interest lies in analysing compositional dissimilarities among whole communities in non-Euclidean (semi-metric or non-metric) multivariate space. Hence, dissimilarity-based tests by permutation (e.g., PERMANOVA, ANOSIM) are used to detect differences among groups of multivariate samples. Such tests are not robust, however, to heterogeneity of dispersions in the space of the chosen dissimilarity measure, most conspicuously for unbalanced designs. Here, we propose a modification to the PERMANOVA test statistic, coupled with either permutation or bootstrap resampling methods, as a solution to the BFP for dissimilarity-based tests. Empirical simulations demonstrate that the type I error remains close to nominal significance levels under classical scenarios known to cause problems for the un-modified test. Furthermore, the permutation approach is found to be more powerful than the (more conservative) bootstrap for detecting changes in community structure for real ecological datasets. The utility of the approach is shown through analysis of 809 species of benthic soft-sediment invertebrates from 101 sites in five areas spanning 1960 km along the Norwegian continental shelf, based on the Jaccard dissimilarity measure.

Although ascidians form a conspicuous part of sessile assemblages in the Caribbean, no specialized inventories have been developed in Venezuela, except for a list of 15 species reported from Margarita Island (1984). Here we present the results of a taxonomic workshop held in the Universidad de Oriente, Boca del Rio, Margarita Island during April 20-25 of 2009, sponsored by the NaGISA-Caribbean Sea program. La Restinga National park was surveyed and we found 29 species belonging to 19 genera and 10 families. The most abundant colonial species were Clavelina oblonga, Aplidium accarense, Polyclinum constellatum, Distaplia bermudensis, Symplegma rubra, S. brakenhielmi, Botrylloides nigrum and Ecteinascidia turbinata. Among the solitary ascidians Phallusia nigra, Ascidia curvata, Microcosmus exasperatus, Styela canopus, Styela sp.1 and Styela sp. 2 were the most abundant. The ascidian diversity in this lagoon is one of the highest for similar habitats in the Caribbean and seven species are new registers for Venezuela (Ascidia curvata, Ecteinascidia styeloides, Aplidium accarense, Distaplia stylifera, Trididemnum orbiculatum, Symplegma rubra, and S. brakenhielmi). One point of concern for the conservation of la Restinga National Park is the presence of possible introduced species, and some management procedures are suggested.

Supplement 1. Taxonomic classification and photographic guide of species registered as epibionts on mangrove roots from Parque Nacional Laguna de La Restinga and Parque Nacional Morrocoy, Venezuela. Adequate taxonomic classification of species was based mainly with local inventories. Most of these studies are undergraduate thesis, books and published papers. Also, personal communications with experts was necessary for some taxa. For sponges, the most important inventories were done by Díaz et al. (1985), Díaz et al. (2003), Pérez (2007) and Young (2010). For tunicates, the only relevant study was carried out by Rocha et al. (2010). Similarly, for anemones, the only reference belongs to González-Muños et al.

Aim We evaluated whether patterns of species diversity (α, β and γ) of rocky shore assemblages followed latitudinal gradients (i.e. LDGs) along the South American coasts, and tested hypotheses related to potential processes sustaining or disrupting the expected LDG pattern at various spatial scales. Location Coasts of South America. Taxon Macroalgae and sessile/slow‐moving macrofauna on intertidal rocky shores. Methods We evaluated changes in species composition across 143 sites. The degree of replacement and loss of species at different spatial scales (i.e. coasts, regions and sites) were estimated to help distinguish among ecological, historical and evolutionary hypotheses for explaining LDGs. Furthermore, components of diversity and taxonomic distinctness were measured, and variability in these measures was decomposed using analysis of covariance. Finally, we examined relationships between diversity and a suite of environmental and anthropogenic variables to identify potential mechanisms that may be responsible for the reported spatial relationships. Results Species composition varied with latitude, and this variability was relatively consistent on both coasts. At all spatial scales, replacement of species was the dominant phenomenon (>95%), rather than loss in the total number of species (<5%). LDGs were strongly dependent on the diversity component and the spatial scale: generally, positive for regional β‐diversity, negative for α‐diversity and site β‐diversity. Sea surface temperature (SST) was the variable that best explained patterns of diversity along both coasts (14%–22%), but other regional and local environmental variables associated with river discharges, upwelling, confluence of currents, tides and anthropogenic pressures also accounted for an important portion of variation (5%–14% each). Main conclusions Species diversity of South American rocky shores followed, with interruptions, LDGs. The trend of those LDGs, however, depended on the scale and metric used to describe diversity. It is proposed that patterns of LDGs at various scales are not the result of a single overarching process but are strongly influenced by local and regional processes. Although the most evident environmental gradient was the decrease in SST towards the south, it was demonstrated that regional and local environmental variables were also important for understanding the increase in regional β‐diversity towards the tropics.

The effectiveness of the immune defense of Litopenaeus vannamei previously reared in biofloc or in a traditional clear seawater rearing system was assessed after a bacterial challenge with a pathogenic strain of Vibrio harveyi. The changes caused by its previous rearing system condition or the challenge were assessed in terms of metabolites (glucose, cholesterol, acylglycerides, protein), hemocyanin, the antioxidant defense system (superoxide dismutase, and catalase), and gene expression related to immune response (superoxide dismutase, alpha2 macroglobulin, prophenoloxidase, hemocyanin, and penaeidin‐3a). The biofloc rearing system was associated with a significant increase in protein, the antioxidant defense system, and the superoxide dismutase, alpha2 macroglobulin, and prophenoloxidase genes. For shrimp previously reared in biofloc, a positive interaction with the presence or absence (control) of V. harveyi significantly affected the hemocyanin concentration, and the interaction between the two rearing systems in shrimp challenged with the bacteria produced a higher transcription of the hemocyanin gene. Likewise, biofloc and clear seawater maintained a higher transcription of prophenoloxidase gene after the bacterial challenge. In the absence of the bacteria, shrimp of the biofloc group produced a higher transcription of the penaeidin‐3a gene. V. harveyi caused hepatopancreatic lesions and mortalities only in shrimp previously reared in clear seawater. These results suggest that biofloc helps to prevent the development of disease by improving the shrimp immune response.

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