Casertanum pea clam
Pisidium casertanum
The Casertanum pea clam is the most widely distributed species of its genus, inhabiting nearly all types of freshwater habitats from small ponds to deep lakes. Its shell is typically oval to rounded and extremely variable in shape, often featuring fine concentric striations. It is known for its high tolerance to oxygen deficiency as well as varying pH levels and water hardness. As a filter feeder, it plays an essential role in the nutrient cycling of aquatic ecosystems.
Details
Identification
Shell usually oval, umbos located behind the middle, surface shiny or dull with fine ribs, color varies from whitish to grey-yellow.
Social behavior
Lives predominantly solitary buried in the sediment, but can occur in very high individual densities.
Diet
Filters detritus, bacteria, and microalgae (phytoplankton) from the water or takes up food particles directly from the sediment.
Overwintering
Remains in the sediment of the water body floor and reduces metabolic activity.
Ecology
Ecological role
Important primary consumer and decomposer that breaks down organic loads and serves as prey for higher trophic levels.
Natural predators
Fish (e.g., carp, tench), waterfowl, predatory leeches, and insect larvae.
Competitor species
Other Pisidium species and juvenile fingernail clams (Sphaerium).
Ecosystem service
Contributes to water clarification through filtration and supports nutrient remobilization in the sediment.
Threats
Habitat loss due to drainage, massive chemical pollution of water bodies, and invasive species.
Scientific profile
Profile
Distinguishing features
The most important features are the posterior position of the umbos and the shape of the cardinal teeth (C2 and C4 in the left valve). The shell is relatively thick-walled compared to other Pisidium species. The species forms numerous ecomorphoses, which can complicate identification; however, unlike P. personatum, it lacks the callus on the interior of the shell.
Diet
Fine detritus, bacteria, diatoms, and other phytoplankton.
Reproduction
Hermaphroditic with the capacity for self-fertilization. The species is ovoviviparous; fertilized eggs develop in specialized brood pouches on the mother's gills.
Role in food web
Primary consumer; converts microbial biomass and detritus into animal protein and serves as an important food source for higher trophic levels.
Protection & threats
Main threats
General degradation of water quality, massive eutrophication, destruction of small water bodies and spring habitats, desiccation due to climate change.
Conservation measures
Protection and restoration of water bodies, preservation of natural riparian structures, and avoidance of excessive nutrient input.