Long-term exposure of the red cherry shrimp Neocaridina davidi to diclofenac: impact on reproductive potential

ZANITTI, MARINA; MEDESANI, DANIEL A.; RODRIGUEZ, ENRIQUE M; LÓPEZ GRECO, LAURA SUSANA

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC

Pharmaceutically active compounds are an important group of emerging pollutants that represent a serious threat to freshwater and marine ecosystems worldwide. Non-steroidal anti-inflammatory drugs (e.g., diclofenac) occupy the first place in environmental presence, compared to other pharmaceuticals. The current study was aimed at studying the long-term effects of diclofenac (DCF) on Neocaridina davidi, concerning its reproductive output especially across successive generations. Both ovigerous females and males of this species were exposed to 0 (control), 0.1, or 1 mg/L of DCF. The experiment comprised 63 days, in order to allow embryo development until hatching in a first reproductive cycle, a subsequent ovarian re-maturation, followed by mating, embryo development, and a second hatching. Shrimps were daily inspected to record egg loss, hatching and new spawning. Recently hatched juveniles were counted and the lecithotrophic index (area of the hepatopancreas occupied by lipid droplets in mm2/total area of cephalothorax in mm2) was quantified. After this, all juveniles were fixed in formalin 5% to analyze morphological abnormalities. At the end of the assay, shrimps were fixed in Bouin, and ovaries were dissected. All oocytes were counted, classified as initial (pre-vitellogenic) or advanced (vitellogenic) and the oocyte´s area was measured. At the highest concentration, the percentage of females with a second spawn, observable from day 45 (full re-maturation takes place approximately 45 d after a previous spawning) increased significantly, while the time between spawns was significantly reduced at both concentrations assayed. However, the ovaries showed a significantly lower proportion of advanced oocytes in females exposed to 1 mg/L, as compared to control. Concerning hatching, the percentage of ovigerous females that had successful hatching was reduced at 1 mg/L of DCF, especially for the first spawn. For the second spawn, the low number of juveniles hatched from females exposed to 1 mg/L showed a significantly higher incidence of morphological abnormalities, such as hydropsy and underdeveloped appendages. Taken together, these results showed that even when DCF was able to produce earlier spawns, the reproductive output of each spawn was reduced.