Ebro Delta Questionaire

1. When did the sea level stabilized in the Mediterranean? How old is the Ebro Delta? • The Mediterranean stabalized 4000 years ago
• The Mediterranean is rising at 1.5 millimetres per year • The Ebro delta dates back to the end of the last ice age it has constantly changed, with the 15th to 16th centuries being the periods of greatest growth for the Delta

2. Which man-induced phenomenon accelerated sediment built up in the Ebro Delta? • Building of Dunes (specifically in 1991)
• Construction of walkways on Dunes to fight against erosion • Removal of infrastructure located on the shore that prevents the normal development of the coastal dynamic • Logging of forests in central Spain because it increased erosion?

3. Which impacts have been caused in the Ebro Delta by the construction of a large number of dams in the Ebro river? • Sediment loss and erosion (sea level is expected to rise 1.5 millimetres per year and the delta is sinking due to the weight of the sediment by between 1-8 millimetres a year) • The surface of the delta isn’t stable because it is not growing from sediment, although the shape changes

4. Sturgeons vanished fro the Ebro delta 40 years ago and giant freshwater clams are highly endangered. Why? • Sturgeons vanished because dams have disrupted the Sturgeon migration for spawning so they can’t leave the delta to reproduce • Freshwater clams are highly endangered because their larvae were parasites of Sturgeons and stick to them in order to be transported upstream where they could grow • The only clams are those from before the Sturgeon vanishment

5. Many freshwater exotic species have been introduced in the Ebro Delta in the past 50 years, but no marine exotic species have been introduced. Why? • People wanted to improve the freshwater fauna by introducing freshwater predatory fish in hopes of increasing fishing in freshwater Marine ecosystems • The Delta had a higher diversity which means it already had a high commercial value 6. The mosquitofish was introduced in the Ebro Delta to fight a fatal illness. Which one? • Malaria, it can be stopped by killing mosquitoes and treating those infected to stop it from spreading

7. Submerged macrophytes vanished from coastal lagoons in the late 1970s but r recolonized them in the mid 1990s. Which processes were involved? Which was the impact of those changes on waterfowl abundance and diversity? • Pesticides and chemicals used by farmers as well as fertilizers from rice fields ran downstream into marshes • The chemicals increased nitrogen and phosphorus and thus increased phytoplankton growth which lead to the collapse of macrophytes • Lack of macrophytes decreased the duck population because they no longer had a food source • Fishing decrease was due to overfishing not to macrophyte collapse • A balance between fresh and salt water needs to be maintained in order to stay away from eutrophication because the ducks prefer fresh water grown macrophytes

8. The Ebro Delta supports a large fishing fleet. Will fish catch be affected by freshwater translocation southern Spain for irrigation? • Yes, the freshwater is better for plants but not for the over production of phytoplankton

9. Rice culture has a dramatic impact on the dynamics of the Ebro Delta. How is vegetation affected by rice culture? Which is the impact on the bird fauna? • Rice Fields need freshwater in the summer during the harvest and salt water I the winter which is the opposite of most deltas • Vegetation can decrease down stream due to eutrophication from the nutrients from the rice fields. Feeding habits of bird faunas increased with more organic harvesting of rice • Fresh water flow allows for more nutrient rich water which allows for plant and phytoplankton growth

10. The seagrass Posidonia oceanica is abundant north to Ebro Delta, but does not exist in the Ebro Delta. Furthermore, it is rare south to the delta. Why? • It needs increased salinity and clear waters with little nutrients which can only be found upstream of the delta not south of it or in it where there is a lot of freshwaters and nutrients from the rice fields and rivers

11. The seagrass Cymodocea nodosa inhabits the bays of the Ebro Delta, but in some areas it has been replaced by free-living green seaweeds. Why? • Outside of the bay by the sand is too loose to support the seagrass roots • In the bays of the delta the sand is much firmer and stays firm for as much as 10 inches

12. Which is the most relevant threat for the conservation of sand dunes? • Due to dams, sand dunes aren’t growing yet are being eroded by winds and water between the ocean and the main landmass • Tourists destroy the vegetation on the dunes and also contribute to the erosion

14. Why the fish living in the costal lagoons of the Ebro Delta have been overexploited? • Because of over fishing and commercial fishing