Mangrove interaction with saltmarsh varies at different life stages.

Mangroves and saltmarshes are two of the most relevant coastal habitats for humans. These ecosystems offer several services like coastal protection, climate mitigation, and nursery habitats for many artisanal and commercially exploited fish, crabs, and shellfish. They mostly dominate different latitudinal ranges but in several places around the world they co-occur and interact. Here, we summarize the current scientific knowledge on mangrove-saltmarsh ecological interactions and propose a conceptual model. We screened 1410 articles from 1945 to 2022 and selected 29 experiments that assessed mangrove-saltmarsh ecological interactions. Both positive and negative interactions are observed but there is variation along different mangrove life stages. Higher retention and establishment of mangrove propagules are found inside saltmarshes than on bare flats, i.e. facilitation, and these effects are higher at grass than at succulent saltmarsh species. Mangrove seedlings, saplings, or trees mostly compete with saltmarshes, negatively affecting mangrove growth. We propose a model with different outcomes considering the interaction between different mangrove's life stages and saltmarsh forms and discussed these interactions in the light of anthropogenic threats and climate change.

Phycotoxins and marine annelids - A global review.

Several species of microalgae can produce potent phycotoxins that negatively affect aquatic organisms and their consumers following different exposure routes, as well as toxicokinetic (TK) and toxicodynamic (TD) processes. Benthic organisms are especially vulnerable as they are exposed to both benthic and planktonic species causative of harmful algal blooms (HABs). While benthic algae can come into direct contact with annelids during substrate remobilization, planktonic cells can settle to the bottom mostly during senescence and/or encystment stages, and in shallow and calm waters. We performed a systematic, qualitative review of the literature on the phycotoxin TK and TD processes in marine annelids, summarizing the most relevant findings and general trends. Besides, by using innovative analytical/statistical approaches, we were able to detect patterns and gaps in the current literature, thus pointing to future research directions. We retrieved and analyzed studies involving diarrhetic shellfish toxins (DSTs), paralytic shellfish toxins (PSTs), brevetoxins (PbTXs), domoic acid (DA), as well as palytoxin and its congeners, the ovatoxins (treated together as PLTXs). It is worth mentioning that studies evaluating other phycotoxins (e.g., ciguatoxins, yessotoxins) were not found in the literature. The absence of data on PbTXs, PSTs and DA is the largest gap hampering TK assessment in annelids, although some relevant information on TD is already available. Whereas lethal effects from DSTs have not been reported, more potent toxins like PbTXs, PSTs, DA and those grouped as PLTX-like compounds can cause mortality and/or marked decrease in annelid abundance. In addition, phycotoxins have been linked to sublethal effects on annelid cells. Although very sparse, field and laboratory studies offer strong evidence that annelids may be reliable indicators of toxin exposure and their negative effects during both early and later stages of HABs in marine environments. Besides quickly responding to these compounds at both organismic and suborganismic levels, annelids are easily found in areas affected by HABs. The use of annelids in future investigations evaluating the action mechanisms of toxic microalgae on marine invertebrates should be thus encouraged. In this case, the choice for widely dispersed and numerically dominant species of annelids would strengthen the validation and extrapolation of results from risk assessments in areas affected by HABs worldwide.

Ten new species of Phyllodoce Lamarck, 1818 (Phyllodocidae, Annelida) from Brazil.

Herein we provide a taxonomic revision of Phyllodoce species from Brazil, describing 10 new species in addition to two new records, Phyllodoce longipes Kinberg, 1866 and Phyllodoce cf. madeirensis Langerhans, 1880. Phyllodoce sp. A. and Phyllodoce sp. B. are probably new but the number and condition of available specimens do not provide adequate and reliable diagnostic features for a formal description. These species have been collected in diverse marine and estuarine environments from shallow estuarine bottoms to continental shelf and slope sediments and submarine canyons from off southern and southeastern Brazil. A key to the fourteen species of Phyllodoce occurring in Brazil is also given.

Euryhalinity of subtropical marine and estuarine polychaetes evaluated through carbonic anhydrase activity and cell volume regulation.

Polychaete worms are widespread and diverse in marine and estuarine habitats subject to varying salinity, in areas influenced by tides, demanding physiological adjustment for internal homeostasis. They are typically considered and reported to be osmoconformers, but they are not often studied for their osmoregulation. Here, three species of polychaete worms from distinct coastal habitats have been investigated: the spionid Scolelepis goodbody (intertidal in saline, exposed sandy beaches), the nereidid Laeonereis culveri (estuarine polyhaline), and the nephtyid Nephtys fluviatilis (estuarine oligohaline). The general objective here was to relate ecological aspects and physiology of the studied species. Constitutive whole body osmolality and carbonic anhydrase activity (CAA, relevant for osmoregulation, acid-base balance and respiration) have been assayed. In addition, cell volume regulatory capacity (from whole body cell dissociation) was challenged under hypoosmotic and hyperosmotic shocks (50% intensity), with respect to isosmotic control. S. googdbody and L. culveri, the two species from most saline environments (marine/estuarine), showed higher CAA than N. fluviatilis, which, in turn, displayed a hyperosmotic gradient to water of salinity 15. Cells from S. goodbody and L. culveri showed regulatory volume decrease upon swelling, with S. goodbody showing the largest volume increase. As in other more studied marine invertebrate groups, polychaetes also show variability in their osmoregulatory physiology, related to distinct saline challenges faced in their coastal habitats.

Metataxonomic and metagenomic analysis of mangrove microbiomes reveals community patterns driven by salinity and pH gradients in Paranaguá Bay, Brazil.

While environmental drivers regulate the structure of mangrove microbial communities, their exact nature and the extent of their influence require further elucidation. By means of 16S rRNA gene-based sequencing, we determined the microbial taxonomic profiles of mangroves in the subtropical Paranaguá Bay, Brazil, considering as potential drivers: salinity, as represented by two sectors in the extremes of a salinity gradient (<5 PSU and >30 PSU); proximity to/absence of the prevailing plants, Avicennia schaueriana, Laguncularia racemosa, Rhizophora mangle, and Spartina alterniflora; and the chemical composition of the sediments. Salinity levels within the estuary had the strongest influence on microbial structure, and pH was important to separate two communities within the high salinity environment. About one fourth of the total variation in community structure resulted from covariation of salinity and the overall chemical composition, which might indicate that the chemical profile was also related to salinity. The most prevalent bacterial phyla associated with the mangrove soils analyzed included Proteobacteria, Actinobacteria, Chloroflexi, Bacteroidetes, Acidobacteria, and Cyanobacteria. Taxonomic and functional comparisons of our results for whole-genome sequencing with available data from other biomes showed that the studied microbiomes cluster first according to biome type, then to matrix type and salinity status. Metabolic functions were more conserved than organisms within mangroves and across all biomes, indicating that core functions are preserved in any of the given conditions regardless of the specific organisms harboring them.

Oxidative stress in two tropical species after exposure to diesel oil.

Recent offshore petroleum exploration has increased the risks of oil spills worldwide. We investigated biomarker responses to diesel oil exposure in two tropical and subtropical species, the clam Anomalocardia flexuosa and the polychaete Laeonereis culveri. Animals were exposed to oil-spiked sediment at two different concentrations (0.5 L and 1.0 L m-2). Activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx); glutathione transferase (GST); and lipid peroxides (LPO) were assessed in bivalve digestive glands and polychaete whole-body homogenates at 36 and 60 h of exposure. Significant variation in enzymatic antioxidant activity depended on the sampling time after exposure. No similar response patterns, either increases or decreases, were detected for the two target species, and biomarker responses were species-specific. L. culveri showed clearer patterns in its antioxidant response and should be prioritized over other species in biomonitoring studies involving oil exposure. Understanding the temporal variability of these biomarkers is a necessary action before implementing them as indicators measures in oil contamination biomonitoring programs. Our results provide a better understanding of biomarker responses in subtropical species, evidencing their potential use as sentinels of oil contamination.

Dissecting the distribution of brittle stars along a sewage pollution gradient indicated by organic markers.

We have assessed variation in brittle star distribution patterns along a contamination gradient identified by fecal steroids and aliphatic hydrocarbons in Paranaguá Bay, southern Brazil. A hierarchical design using multiple spatial scales (centimeters-kilometers) was applied. Generalized linear mixed models (GLMMs) were used to investigate the spatial and temporal variability of brittle stars. Main principal components from the contamination and environmental matrices were used to investigate the best explanatory dataset. The abundance of brittle stars was significantly lower in sites with high concentrations of fecal steroids and aliphatic hydrocarbons. The best model fitting always included components from the contamination gradients, which precludes a purely environmental driving of brittle star abundance. Variability in spatial scales lower than kilometers was probably driven by sediment characteristics. We highlighted the importance of a robust multi-scale sampling design for a better biological indication of coastal contamination.

Description of three new species of Eumida Malmgren, 1865 (Phyllodocidae, Annelida) from Southern and Southeastern Brazil.

We describe three new species of Eumida from shallow estuarine and shelf bottoms from south and southeastern Brazil as part of a regional survey of the family Phyllodocidae. Previous regional records of Eumida sanguinea (Örsted, 1843) are herein referred to Eumida dracodermica sp. nov. The two species differ in the size of the prostomium, the distribution of micropapillae on the proboscis, and the shape of the dorsal cirri. Eumida macrophthalma sp. nov. has much larger eyes than the other two species described herein. The dorsal cirri on anterior median segments are rounded and on median and posterior segments they are asymmetrical and cordiform, longer than the dorsal cirri in Eumida dracodermica sp. nov. The lanceolate median dorsal cirri in Eumida delicata sp. nov. are only shared with E. ockelmanni Eibye-Jacobsen, 1987. It is also possible to diagnose the three species by their dorsal whitish pigmentation patterns on the first segments of living or well conserved animals.

Spatial variability of three benthic indices for marine quality assessment in a subtropical estuary of Southern Brazil.

Indices based on macrobenthic responses to disturbance remain to be adequately tested for the detection of spatial variability by robust sampling designs. We present herein a congruence test to real-world data of the widely used indices AMBI, M-AMBI and BENTIX in tidal flats of a subtropical estuary. We used a hierarchical sampling design to evaluate the spatial variability of the indices in response to distinct levels of sewage contamination. Indices were then tested for correlations with chemical proxies of contamination and for the similarity of responses. BENTIX and M-AMBI produced over- and underestimations of ecological status. We found a low degree of similarity among indices as an expression of the spatial variation of macrofaunal assemblages on their performances. Only AMBI varied at the contamination scale (10(3)m) and was congruent with physical-chemical proxies. Ambiguous responses indicated effects of natural inputs of organic matter rather than environmental quality associated to sewage.

A new empirical index for assessing the vulnerability of peri-urban mangroves.

Environmental vulnerability can be understood as a function of exposure to impacts and the sensitivity and adaptive capacity of ecological systems towards environmental tensors. The present study empirically evaluated the vulnerability of forest stands that make up the subtropical Perequê River mangrove (Paranaguá Bay, S Brazil) as the basis for a more appropriate management of its resources. This mangrove is located in the coastal municipality of Pontal do Paraná (Paraná, Brazil) and is part of the Perequê River Mangrove Natural Park, which is still not under a management plan. This study aimed to contribute to the future management plan of this conservation unit through an environmental diagnosis and an empirical evaluation of its vulnerability. The primary data, collected from 51 plots of 100 m(2) each, involved the evaluation of: 1) the exposure to solid waste, deforestation, trails, landfills, and constructions; 2) the degree of sensitivity according to the environmental conditions of each plot; and 3) the adaptive capacity according to the recovery and reproductive potential and structural complexity of the forests. These data were integrated to compose the empirical index of environmental vulnerability (VI) expressed as VI = (SI + EI) - ACI where SI is the sensitivity sub-index, EI is the exposure sub-index, and ACI is the adaptive capacity sub-index. Empirical indices calculated for local forests varied significantly due to differences in values of SI, EI and ACI. This variability defines the local mangrove as a mosaic of vulnerability conditions and suggests that the planning and implementation of local management actions consider such environmental heterogeneity. Applying or extending these actions should be based on local forest conditions at short spatial scales and should not be applied to the mangrove as a whole.

Is the distribution of the lancelet Branchiostoma caribaeum affected by sewage discharges? An analysis at multiple scales of variability.

Spatial variation in the density and biomass of Branchiostoma caribaeum was analyzed along a sewage contamination gradient identified by fecal steroids in a subtropical estuary, southern Brazil. Sampling, repeated in the austral winter and summer, followed a hierarchical design nested at four spatial scales (sector>1 km; area>100 m; site>10 m; replicate<1 m). Density and biomass were significantly lower at sites characterized by high concentrations of fecal steroids. The best combinations of variables that explained the biological similarities among sites involved contamination indicators. Most of the variation of biological data was found at the smallest scales and could be related with the sediment texture. Our study highlighted the usefulness of a multi-scale perspective to evaluate distribution patterns of benthic invertebrates as a biological indication of environmental pollution. Gradient analyses at larger spatial scales may be invalidated by the patchy distribution of benthic fauna if they do not account for such small scale variability.

Reciprocal experimental transplantations to assess effects of organic enrichment on the recolonization of benthic macrofauna in a subtropical estuary.

Coastal benthic habitats are usually in a state of continuous recolonization as a consequence of natural disturbances or human activities. Recolonization patterns can be strongly affected by the quality of the sediment. We evaluated herein the macrobenthic recolonization of organically enriched sediments through a manipulative experiment involving reciprocal transplants between contaminated and non-contaminated intertidal areas. Regardless of the experimental treatments, the density of the polychaete Capitella sp. was extremely high in the contaminated area as well as the density of the gastropod Cylichna sp. in the non-contaminated area. We rejected the hypothesis that differences in sediment quality would determine macrofaunal recolonization at least in the considered scales of space in meters and time in weeks. The recolonization process in a subtropical estuarine environment was strongly dependent on the migration of adults present in the sediments adjacent to the experimental units.

Effects of an experimental in situ diesel oil spill on the benthic community of unvegetated tidal flats in a subtropical estuary (Paranaguá Bay, Brazil).

The effects of diesel oil on benthic associations from unvegetated tidal flats in a subtropical estuary were experimentally evaluated using a Multivariate Before and After/Control and Impact Model (M-BACI). Impacted treatments were contrasted with controls in 14 successive periods before and after the oil spill. An acute effect was recorded just after the impact, but the recovery to pre-disturbance population levels was extremely fast. The increase in the total density of the benthic community after the disturbance was the result of an increase in the densities of Heleobia australis, oligochaetes, and ostracods, observed in both impacted and control treatments, as a reflection of background variability and not the presence of the contaminant. The experimental spill had little influence on the biological descriptors of the benthic associations, which were resilient or tolerant to oil disturbance at the temporal (147 days) and spatial (cm²) scales used in the experiment.