Racing Stripes: Zebra Mussels' Impact in Northern Waters

Zebra mussels

          In class, zebra mussels have come up many times in our discussions of invasive species, especially when concerning aquatic invasive species.  Zebra mussels originally occurred primarily in Russia and the Black and Caspian Seas, but they are an incredibly resilient invasive; they've colonized and stayed in Great Britain, the Netherlands, the Czech Republic, Sweden, Italy, and much of the USA's north and west.  They are thought to have been spread to the USA by large ships crossing the Atlantic Ocean from Europe and have spread throughout the USA largely from recreational boats.  Similar to other invasive aquatic species, they spread between waterways on recreational boats due to boat owners not washing down their boats well after use.  Because the mussels can survive for days without water, they can ride on the bottoms of boats being brought from one waterway to another, thus colonizing those new waterways.

A sign raising awareness of how invasive zebra mussels are transported

          These zebra mussels can cause huge problems for the ecosystems they colonize.  In Lake Champlain, they kill other native mussels, cover everything from rocks to docks to sandy bottoms to submerged chains with their sharp shells that can harm humans, obstruct water intake pipes, and compete for food resources with other native species.  Although zebra mussels have these negative effects on ecosystems, they also have certain positive effects.  Invertebrates such as insects thrive when zebra mussels colonize waterways because they offer protection from predatory fish.  In an experiment detailed in the Adirondack Almanac this week, areas with zebra mussels were twice as popular with invertebrate populations than areas without them due to their offered protection.  Insects can find cracks and chasms between shells that fish can't access, providing shelter for insects.

Zebra mussels attached to and slowly killing a native mussel in MN

           Last year I learned that the Chesapeake Bay of Maryland and Virginia was having dire problems saving its native oysters from a sharp population crash because of disease, over-harvesting, and habitat loss.  Oysters are a vital part of the Chesapeake ecosystem, acting as a primary filter-feeder.  So after reading about zebra mussels, I was wondering if they could be introduced to the Chesapeake Bay and have a positive impact on the ecosystem, helping the declining oysters filter the bay.  If zebra mussel populations could be monitored and contained, I can see them having at least a somewhat positive impact in the area.  I did some follow-up research on this idea, and, unfortunately, this has not been the case.  Zebra mussels have in fact already invaded the Chesapeake Bay and do much more harm than good.  Although they help with filtration, they maintain the same negative effects and also kill the native oysters that are in decline and still so vital.  Also, because the Chesapeake Bay is such a huge system, zebra mussels have been allowed to spread even more past the Chesapeake.
          Zebra mussels cause huge problems for aquatic ecosystems and cause smaller problems for humans (either in the form of sliced-open feet or financial effort for removal).  If you own a boat and ever transport it between bodies of water, wash it, drain it, and dry it to protect other ecosystems.  If you really want some mussels for dinner one night, you can even eat these killer invaders, but be cautious if you take them from highly polluted waters—then they may even kill you (because you'll get really sick from eating bad mussels).


Sources:
http://cisr.ucr.edu/quagga_zebra_mussels.html
http://www.adirondackalmanack.com/2015/10/understanding-zebra-mussel-impacts-lake-champlain.html#more-56197
http://www.chesapeakebay.net/fieldguide/critter/zebra_mussel
http://www.chesapeakebay.net/issues/issue/invasive_species#inline

Photos:
http://www.chesapeakebay.net/fieldguide/critter/zebra_mussel
http://www.aci-net.org/news/2014/01_hello_zebra_mussels.php
http://www.nytimes.com/2014/02/25/science/science-takes-on-a-silent-invader.html