May 24th 2014
Vravrona is a rather famous archaeological site 30 Km from Athens...
Here we did something different today: a celebration of its fish world! And with special reference to the migratory fishes in the small stream that passes near the site, the Erassinos River.
We celebrated WORD FISH MIGRATION DAY with a scientists' view of the fishes and stream. We sampled fishes using electrofishing at five points on the stream and got a small bunch of participants excited about nature, fishes, what we do....
And there was cause for celebration today: We discovered a "different" Erassinos river, relative to what we had sampled five years back.
The results:
a) Last time we sampled, we had no Marathon Minnows in the stream - an exception being a small population next the Artemis spring inflow (near HOS's wooden bridge, for those who now the site).
b) Last time we sampled we saw that the river was FULL of Mosquito Fish. A highly invasive alien species that is said to out-compete the similar sized - and globally threatened - Marathon Minnow....
c) Last time we sampled the channel of the stream was cleared of Phragmites reed and Mugilids had swam up nearly to the wooden bridge.
d) Last time we caught no eels.
Today we had:
a) Marathon Minnows were dominating the fish community - they were everywhere, abundant but usually small sized (mostly very young fishes). It was difficult to convince our select audience that these are highly threatened species!!!
b) We caught and observed less than ten Mosquito Fish. (An amazing scarcity of this overwise super-abundant fish!!!). Where did these invasive aliens go???
c) Phragmites has choked the river channel (This is the real big change since 5 years ago...). Mugilids came up only about 200 m from the estuary bridge-culvert. All Mugilids were tiny Striped Grey-mullets (Mugil cephalus). Today we had Marathon Minnows with the Mugilids even about 30 m. downstream of the estuary bridge-culvert (they were almost in brakish water...swimming over Posidonia debris...WOW!!!!).
d) We caught 5 Eels! And we didn't try hard. Young elvers (2) also. What a treat!! The most migratory of threatened fishes carefully caught and photographed.
All this has changed in a period of five years!!
Fantastic scientific questions, conservation-relevant questions- we will soon be back to Vravrona....
Cause for celebration!
*Our work was organized under the EcoFlow Project with help from the care-taking NGO, the Hellenic Ornithological Society. I want to thank participants from the Hellenic Centre for Marine Research, Athens University, and the Hellenic Ornithological Society. Another successful partnership. We will do better next time. Look at that last photo....we had a great time!
