Aquatic Ecology最新文献

Citizen science online platforms are increasingly making important sources of biological information available at the click of a button, allowing the interaction of volunteers and scientists to report and identify the world’s diversity. In this work, we combined the data available in citizen science platforms (iNaturalist and GelAvista) and the effort and collaboration of a diverse team of scuba-divers, scientists, and underwater photographers to report for the first time the presence of the stauromedusa Lipkea (Cnidaria: Staurozoa) in Portugal. Based on DNA (COI and 16S), we identified the species as Lipkea ruspoliana. However, the marginal lappets of some Portuguese specimens are similar to those of Lipkea sturdzii, a species described based on a single specimen in 1893 and never reported again. These results suggest that L. sturdzii is a synonym of L. ruspoliana, although further taxon and habitat sampling for genetic studies and investigations of intraspecific morphological variation are necessary. In addition, we provided data on species ecology, reviewed the records of Staurozoa from Portugal, and mapped the world geographic distribution of Lipkea. Staurozoa is a cryptic group of cnidarians, and Lipkea seems to be a particularly rare genus. Citizen science has proved to be a valuable contribution to studies on the group, enabling biological discussions that otherwise would be more challenging.

Invasive species are continuously introduced in several ecosystems from human activities. Aquaculture activities are noteworthy among the many different species introduction vectors currently in place, generating a pattern of constant, frequent or massive release of propagules into aquatic ecosystems, increasing species establishment success rates. Reported cases in marine or brackish ecosystems, however, are still scarce. As aquaculture constantly generate propagules with the ability to employ these facilities as corridors to further spread to interconnected brackish and freshwater ecosystems, colonising high salinity systems, this study aimed to compile evidence of Tilapiines detected in Brazilian coastal marine and brackish ecosystems. Nineteen records were obtained, with the presence of this invader suggested as higher following rainfall seasons. The widespread distribution of Tilapiines is relatively well-known in Brazilian freshwater ecosystems but, up to now, its potential to use brackish and marine ecosystems as ecological corridors has been described only experimentally. Our findings highlight the potential for a typically freshwater invader to spread through marine ecosystems, raising concerns regarding the licensing of aquaculture projects within rivers and estuaries, as tilapia may significantly affect native Brazilian biota.

Data collection by citizen scientists is emerging as an important practice for biodiversity detection, mapping, and compilation of big data in open online platforms such as iNaturalist, acting as a source of biodiversity discovery. However, the validation of species identification is a central issue for the scientific use of these data. Here we compared the list of marine species in the Western Atlantic Ocean obtained in iNaturalist with that generated from scientific collections to understand whether there are taxonomic bias favoring some types of organisms, and to understand the amount of trustful information at the species level in iNaturalist. We also present the first bioblitz results of marine biodiversity in Brazil, an iNaturalist Citizen Science campaign advertised by social media, as a case study. We found that marine taxa with higher richness were well represented in iNaturalist (Arthropoda, Mollusca and Chordata), nonetheless Annelida, Bryozoa, Nematoda, Nemertea, Platyhelminthes, Porifera, Chlorophyta, and Rhodophyta were under-represented. Taxa with small, cryptic, parasitic and/or sessile organisms were poorly represented. According to the methods applied in this study, we showed that 72% of the records are probably well identified, except for Bryozoa and Platyhelminthes. Brazilian marine records in iNaturalist add up to only 1/30 of the total West Atlantic records analyzed but there was a steep increase from 2021 to 2022, as a possible contribution of our bioblitz campaign especially for Arthropoda, Echinodermata, and Annelida. We conclude that the record of marine biodiversity by citizen scientists is a valuable tool, but the engagement of taxonomists is strongly recommended to increase the correct identification of species.

Chinook salmon (Oncorhynchus tshawytscha) is invading South America. Both the high plasticity and genetic diversity of introduced propagules have been hypothesized to be responsible for the success of this species’ invasion. Yet, the influence of environmental variability on the expressed phenology of the adult spawning migration has been overlooked in this region. Here, we examined the consistency in timing, duration, and relative abundance of adult salmon migrants and their associations with environmental river conditions and surrounding ocean in a regulated river system in Patagonia. We conducted monthly long-term snorkeling fish surveys (2010–2019) and collected associated environmental information from the river and ocean. We observed a recent increase in duration of the spawning migration and a decline in the relative abundance of adult migrants. A warming phase of the Southern Pacific Ocean (during the two previous years) was associated to an extended migration season, whereas a colder river in fall was associated to a lower number of adult migrants. Collectively, our findings suggest that rapid phenological shifts could occur in a recently established salmon population (circa 1980). This process could be explained by novel selective pressures and expression of life history traits in response to novel environmental regimes. Further long-term surveys of introduced salmon can aid in parsing the relationships between environmental regimes and the biology and persistence of these self-sustained populations.

Resource fluxes at the stream–riparian interface are a vital contributor to both systems’ energy budgets. The effect of distinct litter exposure patterns—direction of the riparia–stream movement and duration of exposure at each habitat—however, remains to be elucidated. In this field experiment, oak leaves in fine and coarse mesh bags were either exposed to a stream-to-riparia or riparia-to-stream movement sequence for distinct periods (2:6, 4:4, or 6:2 weeks). After 8 weeks, ash-free mass loss, microbial activity, and fungal biomass were compared in leaves undergoing inverse movement sequences (e.g., 2-week exposure to the riparian area at the beginning vs. end of the colonization period). Mass loss in coarse mesh bags was negatively affected when leaves were previously exposed to a short (2 weeks) terrestrial pre-conditioning period, despite higher microbial activity and fungal biomass, when compared to the inverse movement. This effect on mass loss was neutralized by longer terrestrial exposures that likely allowed for a more thorough conditioning of the leaves, through extended leaching and terrestrial microbial colonization. Our results suggest that terrestrial pre-conditioning periods of < 2 weeks lead to litter-quality legacy effects in tough leaves, to which aquatic communities respond through lower substrate degradation efficiency, hindering stream decomposition. Contrastingly, oak aquatic pre-conditioning, regardless of duration, provides riparian communities with a high-quality resource, promoting litter processing through grazing behavior. As climate-induced hydrological shifts may result in altered provision/quality of detritus subsidies at the stream–riparia interface, we suggest that assessments of decomposition dynamics should consider the entire litter conditioning history.

Both heavy metal pollution and plant invasion are serious global environmental problems. Nutrient availability has been shown to influence the performance of invasive plants in heavy metal polluted environments. However, it is still unclear whether the effects of nutrients differ between different forms. We conducted a greenhouse experiment to test the effects of cadmium (0.5, 1 and 2 mg L⁻¹) and nitrogen concentration (0.5, 2 and 8 mmol L⁻¹) as well as nitrogen form (ammonia nitrogen, nitrate nitrogen and glycine) on the invasive, widespread plant Alternanthera philoxeroides. Cadmium did not affect the overall growth of Alternanthera philoxeroides. In the presence of cadmium, plants grew better when provided with nitrate nitrogen than with ammonia nitrogen or glycine. Cadmium interacted with nitrogen level and nitrogen form to affect the growth. At medium (1 mg L⁻¹) and high (2 mg L⁻¹) cadmium levels, promotion of high level nitrate nitrogen (8 mmol L⁻¹) on plant growth was significantly reduced. Our results suggest that the growth performance of Alternanthera philoxeroides in cadmium polluted water is related to both nitrogen level and form. These findings could provide a basis for predicting the spread of Alternanthera philoxeroides in polluted water.

Polycyclic aromatic hydrocarbons (PAHs) are organic chemicals that can induce oxidative stress, genotoxicity, immunotoxicity, endocrine disruption, and developmental toxicity and are carcinogenic. Marine benthic macroinvertebrates are used as biomarkers for elucidating the level of environmental pollution due to their sedentary nature and ability to accumulate toxic compounds over an extended period. Antioxidant defence systems in macroinvertebrates protect cells from reactive oxygen species formed during oxidative stress, and they also counteract the effect of the pollutants through various physiological adaptations and differential expression of specific enzymes. A literature review on molecular studies on various marine benthic macroinvertebrates phyla was evaluated to understand their response to different PAH exposures. Literature shows that genomic tools can define toxicant-specific gene transcriptome variations, which can be utilized to identify the principal pathways that are affected. The review addresses analytical methods, similarities, and differences in antioxidant enzymes and the expression of various genes studied. The comprehensive analysis of literature reveals that several studies have explored the responses of organisms to PAH pollution; this included genes such as CYP450s, GST, SOD, GPx, CAT, and HSPs. Numerous studies have consistently demonstrated notable up-regulations in these genes, establishing their characterization as PAH-sensitive genes, highlighting the critical role played by them for cellular defence and detoxification mechanisms. PAHs can affect organisms depending on exposure time, kind, matrix, and pollutant dose. Benthic macroinvertebrates are robust bioindicators for PAH assessments; thus, environmental risk assessments need a standardized quality and assurance methodology for contamination exposures and biomarker interpretation.

Body elemental composition of consumers is a crucial parameter linking organisms’ attributes to environmental changes. Recent investigations have revealed substantial intraspecific variability in organismal stoichiometry, challenging the assumption that individuals within a population have similar elemental composition. Yet, disentangling the factors that promote intraspecific variation in organismal stoichiometry remains important. Here, we experimentally assessed the effect of diet elemental composition on the stoichiometric traits [percentage and ratios of carbon (C), nitrogen (N) and phosphorus (P)] of two omnivorous species, the red swamp crayfish (Procambarus clarkii) and the pumpkinseed sunfish (Lepomis gibbosus). Sunfish exhibited 6 times higher P and 1.6 times higher N contents than crayfish. Diet composition was an important driver of organismal stoichiometry variation within species, but its effect was also taxon-dependent. Our study revealed that the effects of diet variability on intraspecific stoichiometric traits are important but also contingent on the taxonomy.

Endocrine disruptors can alter biological functions in aquatic organisms at low levels. Triclosan, a commonly used active ingredient in personal care products around the world, is frequently detected in the environment. Likewise, 4-nonylphenol is used in products such as plastics, personal care products, and cleaning agents. Zooplankton species such as cladocerans are used in acute and chronic ecotoxicological assays. Daphnia laevis is a commonly found cladoceran in Mexican water bodies and has been used in previous ecotoxicological experiments. In this work, median effective concentration of triclosan and 4-nonylphenol (EC₅₀, 24 h) for immobilization for the cladoceran were derived. Based on the acute toxicity data (368.6 and 200 µg L⁻¹, respectively), three sublethal concentrations of both compounds (30, 60, 120 and 10, 20, 40 µg L⁻¹, respectively) were used to evaluate population responses. Population growth curves of D. laevis were affected significantly, indicating decreases in peak abundances in all treatments (0.5 for triclosan and 1 ind mL⁻¹ for 4-nonylphenol) compared to controls (2 ind mL⁻¹). The effect of the exposition of both endocrine disruptors was significant in the majority of the treatments; however, 4-nonylphenol was more toxic to D. laevis, than triclosan. This can be explained through the great number of interactions of binding sites on the amino acid, arginine kinase, contributing to the inhibition of the regulation of cellular energy used in survival and reproductive pathways of the cladoceran.

We quantified the feeding behavior (encounter, attack, capture and ingestion) and demographic parameters (survival and reproduction) of the predatory rotifer Asplanchna sieboldii fed on the prey Plationus patulus previously exposed to microplastics (MPs), Cd or their combination. As compared to controls, capture and ingestion rates of P. patulus by A. sieboldii decreased by 71 and 61%, respectively, with prey previously exposed to mixed MPs and Cd treatment. Life table data showed that the predator died earlier in controls than when fed on prey exposed to both Cd and microplastics. Regardless of the prey treatment, the offspring production by A. sieboldii increased as the available prey numbers increased (from 1 to 4 ind. ml⁻¹). Compared to controls, the fecundity rate of the predator decreased when contaminated prey was offered as food.