Encapsulated Amazonian Microalgae Reduce Ammonia and Improve Survival of Female Poecilia reticulata During Simulated Transport

Cobos M.; Guerra M.J.; Pizarro L.J.; Panduro G.R.; Ampudia D.E.; Espinoza-Campos F.O.; Castro C.G.; Castro J.C. · Fishes (2026) · DOI: 10.3390/fishes11060331

Resumen

The accumulation of un-ionized ammonia (NH3) during the transport of live ornamental fish poses a critical threat to animal welfare and post-transport survival. This study evaluated the efficacy of calcium alginate-encapsulated native Amazonian microalgae, Ankistrodesmus sp., Chlorella sp., Scenedesmus sp., and Synechococcus sp., for NH3 bioremediation during a 15-day simulated transport of female Poecilia reticulata. Biometric endpoints were selected using a four-criterion framework, identifying specific growth rate by weight (SGRW), specific growth rate by length (SGRL), and Fulton’s condition factor (K) as essential non-redundant parameters. Time-weighted average (TWA) NH3 served as the primary dose variable for four-parameter log-logistic modeling fitted to biological replicate means (n = 15). Ankistrodesmus sp. and Scenedesmus sp. maintained 97.8% survival and restricted TWA NH3 to 0.036 and 0.047 mg/L, respectively, whereas the empty capsule control reached 6.7% survival and 0.150 mg/L TWA NH3. Kruskal–Wallis tests on biological replicate means confirmed significant treatment effects on all biometric endpoints (SGRW: H(4) = 13.50, ε2 = 0.950; SGRL: H(4) = 13.50, ε2 = 0.95; p < 0.01). Chronic EC50 values of 0.10505 mg/L NH3 (SGRW; Adj-R2 = 0.828) and 0.09967 mg/L NH3 (SGRL; Adj-R2 = 0.812) were established, representing approximately 7.8% and 7.4% of the female-specific acute LC50 (1.34 mg/L NH3), respectively, yielding chronic-to-acute ratios of approximately 13 for both growth endpoints and confirming that sublethal growth impairment precedes lethality. Partial disruption of the calcium alginate capsule matrix was observed from day 5 onward; the relative contributions of encapsulated and free-cell fractions were not quantified. Under the experimental conditions tested, 15-day simulated transport of female P. reticulata under controlled illumination and without feeding, calcium alginate-encapsulated Ankistrodesmus sp. and Scenedesmus sp. treatments represent effective, scalable, and residue-free alternatives to chemical ammonium neutralization for comparable ornamental fish transport scenarios; extension to dark commercial air transport or other species requires further experimental validation.

Instituciones: Universidad Nacional de la Amazonía Peruana