Resumen en inglés

In the live food laboratory of the University of Córdoba, experiments were carried out to establish the effect on specific fecundity, hatching success and morphometric characteristics of the calanoid tropical copepod Acartia tonsa (Bahía de Cispatá) of T1 microalgae diets: Isochrysis galbana (IG), T2: Chaetoceros muelleri (CHA), and T3: the mixture of both algae (IG+CHA) in proportion (1:1) at a concentration of 1500 micrograms of carbon per liter (μgCL−1). likewise, the hatching of eggs spawned and stored at low temperature was evaluated. Experiment 1. The specific fecundity was determined in 225 adult copepods fed with the experimental diets, distributed in three chambers of 6 wells (5 mL/pz) for a total of 18 experimental units; during 5 days the eggs were harvested every 24 hours in each unit, with a record of Female Eggs-1day-1. Experiment 2. Egg hatching was determined in 80 to 100 eggs collected in each experimental diet and distributed in three chambers of 6 wells (10 mL/pz), 48 hours later in each unit the hatched nauplii were quantified under a microscope. Experiment 3. The morphometric characteristics of eggs, nauplii, females, and adult males of A. tonsa, were recorded under a microscope with a micrometric eyepiece in 20 copepods collected at different stages of development on each experimental diet. Experiment 4. The hatching of eggs spawned at five temperatures (18, 20, 23, 26 and 29 °C) and stored cold (2-4 0C) for 4 weeks, was determined weekly in adults housed in triplicate in containers of 2 L at 2.5 copepods.mL−1, fed with the microalga Isochrysis galbana at 1500 μgCL−1. Experiment 1. The highest fecundity was recorded on the third day for T1 (15.0 ± 7.0 eggs day-1 female-1) and T3 (14.0 ± 8.0 eggs female-1 day-1), followed by T2 (6.0±3.0 eggs day-1 female-1) on the first day. Experiment 2. The highest hatching percentage was recorded for T2 (78.8 ± 11.0%), followed by T1 (72.8 ± 7.4%) and T3 (69.2 ± 13.2%). Experiment 3. The diameter of the egg ranged between 85.7 ± 2.0 µm (T2) and 84.3 ± 2.2 µm (T1). The body length (LC) in nauplii ranged between 112.4 ± 8.52 µm (T2) and 115.2 ± 8.2 µm (T3). The females presented a total length (TL) between 997.5 ± 16.0 µm (T1) and 976.3 ± 27.5 µm (T3), and the males a TL between 850.0 ± 31.4 µm (T1) and 843.8±39.6 µm (T3). Experiment 4. At a temperature of 18 °C the highest hatching success was recorded for eggs stored in cold during the four weeks (87.3; 85.9; 83.0 and 73.2%). Microalgae diets for the copepod A. tonsa allowed adequate fecundity and hatching success of the eggs produced. Hatching of cold-stored resting eggs was affected by spawning temperature.