Shrimp culture is quite important and popular across the world. This study aimed to evaluate the growth-promoting potential of synthesized selenium nanoparticles from Spirulina platensis extract (SP-SeNPs) as a food source for Pacific whiteleg shrimp (Litopenaeus vannamei). However, pollution is considered a significant element affecting shrimp health and development. The effectiveness of SP-SeNPs in alleviating the negative effects of cadmium toxicity was also evaluated. Firstly, the shrimps (about 120 individuals with 6.0 ± 0.12 g of initial weight) were divided randomly into four groups in triplicates (30 shrimps/ treatment). The control group (SP-SeNPs—0 mg/kg diet) and three treatments were fed dietary SP-SeNPs (0.250, 0.50, and 1.0 mg/kg diet) for 56 days. Growth performance, digestive enzymes activities (protease, amylase, and lipase), and other biochemical components (total protein, lipid, amino acids, and carbohydrate) were evaluated. After 56 days of growth, another 150 adult shrimps were used under laboratory conditions to determine median lethal concentration of cadmium (96 h LC₅₀), and 30 individuals were treated with cadmium (1/2 of LC₅₀, 0.2 mg L⁻¹) for 10 days only. Tissue samples were collected for measuring catalase (CAT), total antioxidant capacity (TAC), superoxide dismutase (SOD), malondialdehyde (MDA) levels, cadmium bioaccumulation, and histopathological investigation. The results illustrated that the application of SP-SeNPs as feed additives at varying levels significantly improved growth performance (high weight gain, specific growth rate, and low feed conversion rates) relative to the control group. Furthermore, dietary SP-SeNPs enhanced digestive enzyme activities and the concentrations of biochemical components more than the control group. Upon concurrent exposure to cadmium, the antioxidative status was significantly enhanced, and histopathological alterations were mitigated. In conclusion, this study recommended supplementation of SP-SeNPs at 0.50 mg/kg diet to enhance optimal growth rate, digestive enzyme activities, levels of antioxidants in Litopenaeus vannamei, and mitigate the pathological alternations induced with Cd toxicity.

Atrazine is a herbicide commonly used on grain crops. It has been identified as a potential endocrine disruptor, especially in freshwater species. However, there is little research on its endocrine disruptor effect in crustaceans. The current study was designed to estimate the median lethal concentration of atrazine (96-h LC50) and to assess the response of the freshwater crayfish Procambarus clarkii as a bioindicator for endocrine disruptors by measuring levels of steroid hormones, total protein, changes in Cytochrome P450 1B1, and histopathology of the ovary and testis. The results showed that the 96-h LC50 of atrazine for male and female P. clarkii was 10.62 and 12.66 mg L−1, respectively. LC10 (1.06 and 1.27mg/l) and LC25 (2.66 and 3.17 mg/l) values for males and females, were chosen for sublethal studies for 28 days. The results indicated that females are more tolerant to atrazine than males. Testosterone and total protein levels were significantly lower, while estradiol and progesterone levels were significantly higher in atrazine-exposed crayfish compared to the control. Also, the levels of CYP450 1B1 increased significantly in the testis, ovary, and hemolymph. The most noticeable histopathological changes in the testis were distorted architecture, spermatogonia distribution disruption in some testicular acini, Vacuolation, and hyperplasia. In the ovary, the separation between the ovarian epithelium and oogenetic pouch and lysis in the ovarian epithelium was noted. These parameters could be used as biomarkers to assess herbicide toxicity. Furthermore, P. clarkii could be used as an indicator of endocrine-disrupting chemicals in waterways.

Heavy metals pollution has major health consequences for wildlife. This study aimed to evaluate the concentration of heavy metals including arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and selenium (Se) in soil samples, as well as kidney and blood samples of the cattle egret (Bubulcus ibis) at two sites in Sharkia Province, Egypt: urban site (I) and rural site (II) during summer and winter 2021-2022. Some hematological and biochemical parameters, and renal ultrastructural alternations of the birds were evaluated. The results showed that the highest metal concentrations were recorded in the soil of the both sites in the summer. Metal concentrations in the soil, and kidney and blood samples of site "I" were significantly higher than those of site "II", except for Cr that was found in low levels. Alarming concentrations for As, Pb, and Se levels were found in the kidney samples of egrets in both sites. Egrets collected from site "I" showed a significant decrease in the red blood cell count (RBCs), hematocrit (Hct) value, and hemoglobin content (Hb), and an increase in the white blood cell count (WBCs), and serum creatinine and urea levels when compared to those of site "II". Furthermore, severe damage and enlargement in the renal tissues were observed in the cattle egrets of site "I" when compared to those of site "II". Based on these findings the heavy metals contamination in the surrounding environment can be predicted by alterations in hematological parameters and kidney functions in Cattle egret.