Every now and then I get interested enough in language to ask questions of our hosts. There are various French language terms for enclosed (as opposed to flowing) bodies of water, including plan d’eau, lac and étang. The term plan d’eau seems to be applied to a body of water most often providing recreational facilities, but I’d wondered if there was a difference between lac [literally lake] and étang [pond, according to our dictionary]. Étang = pond is clearly not quite accurate because we’ve visited the Étang des Aulnes which approaches the size of an inland sea [slight literary exaggeration] and would never be described in English as a pond. I put my question to farmer Luc.
Luc’s explanation was that an étang is formed naturally whereas a lac is manmade/dammed. I’ll go along with this for the moment while I look for a few more examples.
As well as keeping a close eye on farmer Luc’s lac one other nearby lac that we have been visiting is the Lac de Lenclas. Both certainly fit Luc’s definition, both being formed by a digue [dyke]. The Lac de Lenclas is surrounded on its other sides by a bend in a section of La Rigole, the engineering masterpiece of a small canal that feeds water into the high point of the Canal du Midi. Lac de Lenclas was the first place I ever saw the captivating Violet Darter (Trithemis annulata). Thus, it holds a special place in my heart. This year it surpassed any expectation and has certainly become the star spot for Odonata round here, producing a few southern specialists, one of which was particularly unexpected.
The first celebrity I spotted, working La Rigole just beside the car park, was a Southern Skimmer (Orthetrum brunneum), a species which I’ve seen only twice before. Working our way along the digue to do a circuit of the lake, we did find a couple of Violet Darters, too.
My biggest surprise came part way round the circuit when, watching the common-as-muck Western Demoiselles (Calopteryx xanthostoma) flitting about, I fancied I spotted a demoiselle of the wrong colour. I took a distant snap – it was, of course, incorrectly positioned on the far side of the canal – for later scrutiny. Towards the end of our circuit, however, later scrutiny became unnecessary when we saw what was clearly a Copper Demoiselle (Calopteryx haemorrhoidalis). Quelle surprise!
During our circuit we’d be seeing various clubtails flying around, too, and I’d snapped as many as possible. I had recognized clubtail relative, another of the Gomphidae, a Small Pincertail (Onychogomphus forcipatus), but the clubtail identities required closer examination. I was surprised to find that this area was home to three different clubtail species – 4 Gomphs in all. This is perhaps due to there being essentially two different types of habitat in the small standing lake and the gently flowing canal.
Our first day’s haul for the Lac de Lenclas was 16 species but we added two more on a second visit making 18 in all. Good news.
Sadly (for me, anyway), farmer Luc’s lac could hardly be in starker contrast. During our three week stay, we have actually seen nine identified species which, by itself might imply that all is well. However, seven of those species have only been seen as singletons or, at best, twos. Furthermore, we haven’t seen them regularly. For example, there was an Orange Featherleg (Platycnemis acutipennis) flitting about the campsite two weeks ago but I’ve not seen it since. Similarly, we did spot a couple of Willow Emeralds (Lestes viridis) but we haven’t now seen one for over a week. Only two species have been seen regularly and those in modest numbers: Black-tailed Skimmers (Orthetrum cancellatum) and Blue-tailed Damselflies (Ischnura elegans). An almost complete crash compared to its former count of 18 species recorded by ourselves.
Add to this the complete lack of water birds and really the only life left in this vegetation-free lac is fish and a small, apparently ageing population of frogs. Sad news.
Farmer Luc seems to know his lac is “dead/dying”; at one evening gathering Nadine asked me why the dragonfly population was so low. I did what I could to explain in the hope that some corrective action might result.