Effect Of Temperature,Salinity,pH And Algal Species On The Ingestion And Metabolism Of Two Marine Copepods

Marine copepods belong to Arthropods, Copepoda. They play an important role in stability of the marine ecosystem. Forming a main link between primary producers and higher trophic levels. Marine copepods, moveover, are rich in long chain poly-unsaturated fatty acids, easy propagation characteristics. Commercial hatcheries using them as live feeds. Besides, marine copepods are small, short life cycle, vulnerable to the effects of changes in environmental conditions, which make them as good organism models in the field of environmental toxicology. However, collecting from the wild can not meet the demand of toxicology experiments on a large number of single sample, long-term multi-generational exposure. Fundamental researchs such as ecology and physiology are required for reliable continuous culture. Futhermore, The exploration of culture conditions of marine copepods can also benefit from promoting large-scale production in aquaculture. Different species of marine copepods, even of the same species in different developmental stages, requires specific environmental conditions and food needs. We examine Calanoida copepod Schmackeria poplesia and Cyclopoida copepod Oithona similis. Focus on the impact of environmental factors (temperature, salinity and pH) on feeding, oxygen consumption and ammonia excretion.we want to provide theoretical support for the indoor cultivation of two species copepods. Meanwhile, we measured ingestion and reproduction of O.similis in different types of algae, a preliminary exploration of the proposed multi-generational culture of O. similis.The results of the present study:1. In the condition of Salinity30, pH8.10, S.poplesia (acclimation temperature12℃) and O.similis(acclimation temperature15℃), the optimum feeding temperature is15℃and25℃, respectively.2. O.similis compared to S.poplesia whether ingesting or metabolic level, have shown a temperature change tolerated.3. In the low-salt environment (salinity<30), the S.poplesia response to low salinity stress by increased food intake and metabolic; when salinity is below25, O.similis metabolism increases while feeding ability reduced in contrast. 4. In the high salt environment, the ingestion ability and O/N ratio of two copepods appears to reduced by more protein consumption, to withstand high salinity stress.5. Optimum feeding pH of O.similis and S.poplesia is9.00and8.00respectively; the oxygen consumption and ammonia excretion are stable with pH Change in O.similis, while the variation range of S.poplesia is relatively large.6. For S.poplesia., when the pH is lower than8.00,the ingestion, metabolism and O/N ratio appear to decrease, at a pH of6.00, the minimum value of O/N ratio is4. While when the pH is higher than8.00, although the feeding and metabolism appear to reduce the same, O/N ratio has continued to rise and has a maximum value59.7. For O.similis, the ingestion rate appeared to rise in the pH boost from9.00to8.00, while metabolic drop to the lowest level, which is more suitable for long-term survival. Continue to reduce the pH to acidic conditions, the metabolism of O.similis increased, In contrast ingestion rate decreased, demonstrated the physiological response to environmental stress reaction.8. When feeding with Isochrysis galbana defecation amount and nauplii production of O.similis female are the highest. The defecation amount of Phaeodactylum tricornutum group is similar to I.galbana group,while the nauplii production of P. tricornutum group is significantly low (P<0.05).9. Thalassiosira weissflogii group produced nauplii amount is the lowest,In contrast the group have maximum ingestion rate of6species of algae, illustrate the performance of the diatom T.weissflogii have suppression on reproduction of O.similis.