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The effect of emergent compounds and climate change in aquatic organisms with different early life history strategies

Final Report Summary - EARL (The effect of emergent compounds and climate change in aquatic organisms with different early life history strategies)

Main Results:
Diclofenac sodium (DS) and Clofibric acid at environmental concentrations (10 and 20 µg/l, respectively) do not have any effect on survival, duration of development, growth and body mass of larvae under optimal environmental conditions. However, under environmental stress (food limitation), DS reduced larval survival.
Clotrimazole (CLZ) has toxic effect at lower concentrations (0.14 µg/l) than Diclofenac sodium and Clofibric acid. CLZ at low concentration decreased the larval growth rate in P. serratus larvae. These effects were stronger under environmental stress. CLZ decreased larval survival and larval body mass under food limitation and osmotic stress, respectively. In particular, this compound affects development as it modifies intermoult duration and the number of larval instars required to reach the first juvenile stage. Monitoring the future changes in concentrations of CLZ may constitute a priority for programmes of environmental monitoring.
The effects of these emergent compounds on larvae appear to be compound-specific and species dependent: At high concentrations, DS decreased growth rate in P. serratus, and growth rate and larval body mass in P. longirostris; AC increased duration of development in P. longirostris and decreased growth rate and larval body mass in P. varians; CLZ affected the survival, growth rate and body mass in P. serratus.

Effects of emergent compounds on growth and development of early life stages were stronger when organisms were under some additional stress. At high concentration and under some type of stress survival was affected by DS, AC and CLZ. Additionally, CLZ had more toxic effects: increased duration of development, decreased growth rate and larval body mass under daily variation of temperature in P. varians larvae and decreased growth rate under food limitation in P. serratus larvae.
Mixture effects were stronger compared to effects of exposure at one of these pharmaceutical in P. varians larvae. At daily variation of temperature, the mixture of these three compounds at low concentration increased duration of development and at high concentration also decreased clearly larval growth rate and larval body mass.
Some effects of emergent compounds appeared later during juvenile phase. At daily variation of temperature, P. varians larvae which were exposed to CLZ did not show any significant effects but significant reductions of growth rate and larval body mass were exhibited in juveniles. Also other effects as growth rate and larval body mass were exacerbated reduced in juveniles compared to larvae.
This project manifested the importance to test environmental risk assessment taking into account species specific habitat conditions, the mixture of different emergent compounds and consider more than one stage (embryonic, larval, juvenile or adult) in species with complex life cycle.

The work carried out to achieve the project's objectives were split in different experiments according to the species and the stressful environmental condition:
0.- Preliminary results: Effects of clofibric acid (CA) and diclofenac sodium (DS) at low and high concentrations on larvae of the three species of crustacean decapods at 2 temperatures (18°C and 24°C) and 2 salinities depending on the species (i.e. 20 and 32 for both Palaemon serratus and P. longirostris; and 5 and 32 for Palaemonetes varians).
1. - Experiment 1 (January-March 2012): Effects of AC, DS and CLZ at low and high concentrations at 2 temperature (18˚C and 24˚C) and 2 salinities (20 PSU and 32 PSU) in the common prawn Palaemon serratus.
2. - Experiment 2 (June-July 2012): Effects of AC, DS and CLZ using low and high concentrations in combination with a stressful environmental condition (food limitation) in larvae of crustacean decapods using as a model species the common prawn (P. serratus).
3. - Experiment 3 in larvae of the saltmarshes shrimp P. varians (July-August 2012): Effects of AC and DS at high concentrations and mixing them at low and high concentrations, 2 temperatures (18˚C and 24˚C) and 2 salinities (5 PSU and 32 PSU). Effects of low and high concentrations of AC, DS, CLZ and mixing AC and DS at 5 PSU of salinity and variable temperature of 12:12 h 18C:24C simulating daily changes temperature of marshes. This experiment was designed to test possible accumulated effects after metamorphosis.
4. - Experiment 4 in larvae of the estuarine shrimp P. longirostris (June-July 2013): Effects of AC and DS at high concentrations and mixing them at low and high concentrations, at 2 temperature (18˚C and 24˚C) and salinity 20 PSU. Effects of low and high concentrations of CLZ at 18˚C and salinity 20 PSU.
The exposure to pharmaceuticals is carried out as follows: a control treatment (without pharmaceuticals) and specimens exposed to environmentally relevant concentrations of the three selected pharmaceutical compounds and also concentrations 20-40 times higher than those found in nature to explore thresholds concentrations that lead to sublethal effects.

Socio-economic implications and methodological relevance of the “Earl” project:

The results of this project have high relevance on the impact water quality on the human society and economy. The selected species are abundant along the European coast and are also ecological and economically important. The higher toxicity of Clotrimazole compared to Diclofenac or Clofibric on physiological traits on larvae of these crustacean decapods are relevant to impulse the analysis the occurrence of Clotrimazole in European coastal waters. Clotrimazole could affect individuals and populations that are relevant for aquaculture and fisheries research with a high impact on economy. Our results may give general indications of the potential effects on other species of crustacean decapods with a high economic importance on Penaeus species. The present project should therefore be a milestone for the development of this line of research in Europe.

This project increases our understanding of the impact of climate-driven variables and anthropogenic stress on these species. Aquatic species which inhabit coastal ecosystems are commonly under some environmental stress. Our results show how effects of emergent compounds on growth and development of early life stages were stronger when organisms were under some additional stress. Additionally, some effects of emergent compounds appeared later during juvenile phase. An assessment of the effects of emergent compounds should take into account some type of stress in the experimental design and consider more than one stage (embryonic, larval, juvenile or adult) in species with complex life cycle.

The inclusion of larval biology has been novel since this is a new and developing field of research, where techniques to successfully rear larvae were developed recently. At present research on larval biology and trait-mediated effects in the marine environment are scarce, especially in Europe and for species of economic importance. Future research on the effects of pharmaceuticals on physiological process or on the effect of pollution on ecosystems should follow our methodology as a guide.