How does increasing temperature affect the toxicity of bisphenol A on Cryptomonas ovata and its consumer Daphnia magna?

The global rise in plastic production has led to significant plastic deposition in aquatic ecosystems, releasing chemical compounds as plastics degrade. Among these, bisphenol A (BPA) is a major global concern due to its endocrine-disrupting effects and widespread presence in aquatic environments. Furthermore, the toxicity of BPA on aquatic organisms can be modulated by global change stressors such as temperature, which plays an essential role in the metabolism of organisms, including the degradation and accumulation of toxic compounds. In this study, we aimed to understand how temperature can modulate the toxic effect of BPA on a phytoplankton species (Cryptomonas ovata) and how this effect can be transferred to its herbivorous consumer (Daphnia magna). To do this, we first determined the sensitivity of C. ovata over a BPA gradient (0-10 mg L-1). Subsequently, we experimentally determined how the increase in temperature (+5ºC) could modify the toxic effect of BPA on the physiology, metabolism and growth of the phytoplankton. Finally, we investigated how this effect transferred to the growth rate of D. magna through food. Our results show a negative effect of BPA on C. ovata from 5 mg BPA L-1, affecting its photosynthetic yield of photosystem II, net primary production, respiration, and growth. This effect was accelerated when the temperature was higher. Additionally, the growth rate of D. magna also decreased when fed on C. ovata grown in the presence of BPA and high temperature. Our results indicate that high temperature can accelerate the toxic effects of BPA on organisms located at the base of the food web and this effect could be transferred to higher levels through food.

Constant and fluctuating high temperatures interact with Saharan dust leading to contrasting effects on aquatic microbes over time.

Mediterranean lakes are facing heightened exposure to multiple stressors, such as intensified Saharan dust deposition, temperature increases and fluctuations linked to heatwaves. However, the combined impact of dust and water temperature on the microbial community in freshwater ecosystems remains underexplored. To assess the interactive effect of dust deposition and temperature on aquatic microbes (heterotrophic bacteria and phytoplankton), a combination of field mesocosm experiments covering a dust gradient (five levels, 0-320 mg L-1), and paired laboratory microcosms with increased temperature at two levels (constant and fluctuating high temperature) were conducted in a high mountain lake in the Spanish Sierra Nevada, at three points in time throughout the ice-free period. Heterotrophic bacterial production (HBP) increased with dust load regardless of the temperature regime. However, temperature regime affected the magnitude and nature of the interactive Dust×T effect on HBP. Specifically, constant and fluctuating high temperature showed opposing interactive effects in the short term that became additive over time. The relationships between HBP and predictor variables (soluble reactive phosphorus (SRP), excreted organic carbon (EOC), and heterotrophic bacterial abundance (HBA)), coupled with an evaluation of the mechanistic variable photosynthetic carbon use efficiency by bacteria (%CUEb), revealed that bacteria depended on primary production in nearly all treatments when dust was added. The %CUEb increased with dust load in the control temperature treatment, but it was highest at intermediate dust loads under both constant and fluctuating high temperatures. Overall, our results suggest that while dust addition alone strengthens algae-bacteria coupling, high temperatures lead to decoupling in the long term at intermediate dust loads, potentially impacting ecosystem function.

Eelgrass-associated mesograzers limit the distribution of bloom-forming Ulva via top-down control of its early life stages.

Macroalgal blooms pose a threat to coastal ecosystems worldwide, especially in highly eutrophic environments. Excess nutrients often facilitate the proliferation of opportunistic algae, but in some systems grazing activity counterbalances its effects. I evaluated the regulating role of mesograzers associated with eelgrass (Zostera marina) in Elkhorn Slough, a eutrophic estuary where Ulva spp. blooms are frequent during the upwelling season. I monitored recruitment and transplant success of Ulva spp. along transects placed across the edge of the largest Z. marina bed. Changes in abundance of Ulva spp. on transplants differed spatially and seasonally, and were significantly correlated with density of both small and large invertebrate groups. Grazing affected not only adult Ulva spp. but also its early developmental stages, leading to decreased Ulva spp. abundance on transplants and minimal recruitment inside the Z. marina bed.

Validation of the Preverbal Visual Assessment (PreViAs) questionnaire.

BACKGROUND: Visual cognitive integrative functions need to be evaluated by a behavioral assessment, which requires an experienced evaluator. The Preverbal Visual Assessment (PreViAs) questionnaire was designed to evaluate these functions, both in general pediatric population or in children with high risk of visual cognitive problems, through primary caregivers' answers. AIM: We aimed to validate the PreViAs questionnaire by comparing caregiver reports with results from a comprehensive clinical protocol. STUDY DESIGN: A total of 220 infants (<2 years old) were divided into two groups according to visual development, as determined by the clinical protocol. Their primary caregivers completed the PreViAs questionnaire, which consists of 30 questions related to one or more visual domains: visual attention, visual communication, visual-motor coordination, and visual processing. Questionnaire answers were compared with results of behavioral assessments performed by three pediatric ophthalmologists. RESULTS: Results of the clinical protocol classified 128 infants as having normal visual maturation, and 92 as having abnormal visual maturation. The specificity of PreViAs questionnaire was >80%, and sensitivity was 64%-79%. More than 80% of the infants were correctly classified, and test-retest reliability exceeded 0.9 for all domains. CONCLUSIONS: The PreViAs questionnaire is useful to detect abnormal visual maturation in infants from birth to 24months of age. It improves the anamnesis process in infants at risk of visual dysfunctions.

Development of the Preverbal Visual Assessment (PreViAs) questionnaire.

BACKGROUND: Visual cognitive functions of preverbal infants are evaluated by means of a behavioral assessment. Parents or primary caregivers may be appropriate to certify the acquisition of certain abilities. AIMS: To develop the PreViAs (Preverbal Visual Assessment) questionnaire to assess visual behavior of infants under 24 months of age and to assess the normative outcomes for each item at each age. STUDY DESIGN: The process was divided into three phases: scale development (items and domains generation), pilot testing, and exploratory analysis. RESULTS: The final version of the PreViAs questionnaire consisted of 30 items, each related to one or more of four domains (visual attention, visual communication, visual-motor coordination, and visual processing). For the exploratory analysis, 298 children (159 boys and 139 girls) were recruited. Their ages ranged from 0.1 to 24 months (mean, 11.2 months). Internal consistency of the questionnaire was high for all domains (Cronbach's α coefficients of 0.85-0.94). CONCLUSIONS: The PreViAs questionnaire is a useful scale for assessing visual cognitive abilities of infants under 24 months of age. It is easy and feasible to complete by primary caregivers.