EDP Foz-Tua: Dragonflies and Damselflies (Odonata) - Ecological Monitoring Program (2011-2017)

Study Extent

The data were collected within a 5-km buffer around the lower Tua River valley (Northeast Portugal), up to 45 km from the mouth in the municipalities of Carrazeda de Ansiães, Vila Flor, Alijó, Murça and Mirandela.

Sampling

Sampling was designed to cover the main habitat types for Dragonflies and Damselflies in and around the lower River Tua valley affected by the Foz Tua dam and in the Ferradosa stream (Douro basin). Each sampling point was visited twice per year in spring (April-June) and summer (July-August). The sampling aimed to detect both adults and larvae/exuvia of the target species. Adults were monitored during their flight period, between 9:30 and 16:30, on days with appropriate weather conditions (temperature above 13ºC, light wind, little cloudiness, no rain or fog), with a hand-held net. Sampling took place for 15 minutes, during which the sighted individuals were recorded within a 5m range, and the sorrounding vegetation was carefully prospected. Reproductive behavior (individuals in tandem and ovoposition) and territorial behaviors were duly recorded. Specimens were identified in the field using appropriate guides Observations made in a non-systematic manner, particularly during the study area, were also recorded. All individuals were releasad after identification. Larval samples were collected using a hand-held net with a circular section of approximately 30 cm in diameter and 1 square-mm mesh. Also, 15-minute sweeps of the margins in each river/stream were performed in the opposite direction of the current, in order to sample different habitats (rock zones, vegetation). Two replicates were taken at each point, in places with the same characteristics, but not coincident. The samples were screened in the field and the relevant material fixed in situ with 80% alcohol for later identification in the laboratory. The collection of the exuvia was done by prospection of the vegetation around the water line for 15 minutes, in order to verify the presence of this type of structures. These were collected and stored in vials, duly labeled, for later identification in the laboratory, using specialized bibliography.

Quality Control

All identifications were performed by qualified technicians

Method steps

1. To be completed

The taxonomic coverage of this dataset spans 1 phylum, 1 class, 1 order, 10 families, 23 genera and 40 species.

1. Arthropoda
   rank: phylum
2. Odonata
   rank: order
3. Aeshnidae
   rank: family
4. Calopterigidae
   rank: family
5. Coenagrionidae
   rank: family
6. Cordulegastridae
   rank: family
7. Corduliidae
   rank: family
8. Gomphidae
   rank: family
9. Lestidae
   rank: family
10. Libellulidae
    rank: family
11. Macromiidae
    rank: family
12. Platycnemididae
    rank: family

The data were collected within a 5-km buffer around the valley of the River Tua (Northeast Portugal), in Trás-os-Montes e Alto Douro region, up to 50 km from the mouth, in the municipalities of Carrazeda de Ansiães, Alijó, Murça, Vila Flor and Mirandela.