In Varano lagoon (Puglia, Italy) the bivalve Loripes lacteus (Linnaeus, 1758) constitutes the most
abundant species among the organisms of the benthic macrofauna. This work presents the results
of five years (from 2001 at 2006) of observations on the abundance, size/age population structure
and spatial distribution of this species within the basin (6500 ha). L. lacteus is one of the most
common and frequent bivalve species in Mediterranean lagoons. It typically occurs in reduced
sediments where it is able to live at low oxygen concentration due to a particular respiratory pigment
haemoglobin. Lucinid bivalves house symbiotic, sulphur-oxydizing chemoautotrophic bacterias in
their gills, which contribute substantially to their nutrition.
2 - The design was to perform two sampling campaignes on yearly basis during the intermediate seasons
(Spring and Autumn), when possible. Each sampling was realized collecting 53 sampling units taken
from 53 stations distributed regularly over the lagoon surface. Each sampling unit consisted in all
the individuals contained in a solid 15 x 15 x 20 cm of sediment and held on 1 mm mesh.
3 - Growth patterns were determined with the Bhattacharya method which uses modal progression
analysis from size frequency distribution.
4 - The results showed a spatial distribution of L. lacteus which occurred in patches and changed among
samples. The population analysis showed two modal classes for each sampling time.
5 - L. lacteus is an “r” strategy species with small size, brief life cycle, with great capacity of recovery
after environmental crises.
