19 of 42

See the open mouth of my suitcase
Sayin' leave this place
– Soul Asylum, from 'Leave Without A Trace'

Minnesota Department of Natural Resources information on the mussels of the Minnesota River states that 19 of 42 native species are extirpated from the watershed. This shocking statistic is a direct result of land use in the watershed. Today's observation, a Giant Floater (Pyganodon grandis), comes from an adjacent watershed, that of the Cannon River. A recent survey of the Cannon River lists fifteen species as still being present; it's uncertain what species have been lost. Just as in the song lyric quoted above, a dead mussel, the two parts of the shell still attached at the hinge but open, resembling an empty suitcase, presents a strong image of departure.

This particular species, however, is not yet threatened. Giant Floaters are still very common because they are generalists and can be found in small streams, impoundments, and lakes and, in addition, they are relatively tolerant of pollutants. They are one of the few mussels that can thrive in habitats with little or no current and with muddy or silty bottoms. The glochidia of the Giant Floater, the parasitic larval stage of the mussel, is not limited to a single host fish but hitches a ride in the gills of most of the fish species that live in the river, which further explains this mussel's hardiness and the wide distribution.

Publicado el febrero 16, 2017 04:50 MAÑANA por scottking