Ballast Water    

Galveston Bay is the largest estuary in Texas (Gulf of Mexico, USA), and is highly productive in terms of oyster and seafood production (brown and white shrimp, blue crabs and oysters) second only to Chesapeake Bay in the US. Studies in this ecosystem are important given the frequency and magnitude of ship traffic and ballast discharge into its three ports (Galveston, Houston and Texas City). Steichen et al. (2012) reported that more than 45,000 vessels traveled across Galveston Bay between 2005 and 2010, discharging a total of 1.2 x108 metric tons of ballast water into the Bay itself. BW discharge was found to be an important propagule source of dinoflagellates based on the origin of vessels arriving to Galveston Bay from both domestic and foreign ports of origin (Steichen et al., 2012). Galveston Bay receives more ballast water discharge than both Chesapeake and San Francisco Bays combined (Steichen et al., 2012; Steichen, 2013). This is important considering the Chesapeake and San Francisco bays are two highly invaded estuarine systems.

Over the last century, propagule pressure of non-indigenous species has increased, especially in estuaries and coastal waters. Global movement of nonindigenous species, within ballast water tanks across natural barriers, threatens coastal and estuarine ecosystem biodiversity.  Ballast water is thought to be the primary vector in dispersal and introduction of NIS species of aquatic organisms to ports around the world and new invasion pathways are developing as a result of increasing trade and expanding shipping transport routes. Studies conducted in this lab support the hypothesis that global commerce by shipping contributes to long-distance transportation of eukaryotic microorganisms, increasing propagule pressure and invasion supply on ecosystems (Steichen et al, 2012, 2014 and 2015).

Testing phytoplankton viability within ballast tanks and receiving waters of ballast water discharge remains understudied. Potentially harmful dinoflagellates and diatoms are transported via ballast water to Galveston Bay, Texas (USA). During this project we have identified various genera of phytoplankton from the ballast water of vessels transiting the North Atlantic including those with the potential to cause harmful algal blooms including: Alexandrium, Dinophysis, Gymnodinium, Gyrodinium, Heterocapsa, Peridinium, Pfiesteria, Scrippsiella, Chaetoceros and Nitzschia (Steichen et al, 2012, 2014 and 2015). Phytoplankton, including those capable of forming harmful algal blooms leading to fish and shellfish kills, are transported to Galveston Bay via ballast water, and are viable when introduced to similar salinity conditions found at ports in Galveston Bay.