Bacterial dynamics in ballast water during trans-oceanic voyages of bulk carriers: environmental controls

Abstract

Bacterial abundance, population dynamics, and related environmental parameters were determined in ballast water during 2 trans-Pacific voyages from Japan to the west coast of Canada and 2 trans-Atlantic voyages from the Netherlands to the east coast of Canada. Water samples were collected from ballast tanks that either underwent mid-ocean exchange (MOE) or were unexchanged (control). Bacterial abundances in the MOE and control tanks were not significantly different at the end of the voyage. Moreover, abundances were not lower immediately after compared with immediately before MOE, suggesting that MOE alone is not effective in reducing ballast water bacterial abundances. Results of this study suggest that the duration of the voyage plays a critical role in determining the potential bacterial propagule pressure. Although the bacterial growth dynamics were complex, we found robust relationships and a highly significant predictive relationship between bacterial abundance and both temperature and dissolved oxygen concentrations of the ballast water (p < 0.001). This robust relationship allows the prediction of potential bacterial propagule pressure from environmental characteristics within the ballast tanks.

Taxon‐ and vector‐specific variation in species richness and abundance during the transport stage of biological invasions

“…However, both authors reported a decline in abundance of taxa at the end of voyages, possibly related to fluctuating and inhospitable conditions in ballast tanks. Environmental conditions can change dramatically in ballast tanks, including in temperature of up to 20uC, in dissolved oxygen of up to 6 mg L 21 , and salinity of up to 15% (Klein et al 2010;Seiden et al 2011;Simard et al 2011). These findings are in agreement with our results.…”

“…Although abundances were highest for most taxa in Atlantic ships, and species richness was highest in Pacific ships, both regions were exposed to propagules of all five taxonomic groups studied. Regional differences in abundance may be partially explained by mortality of species due to voyage length (Klein et al 2010;Seiden et al 2011;Simard et al 2011), with voyages to the Pacific region being nearly twice as long as those to the Atlantic region. In addition, Seiden et al (2011) reported regrowth of bacteria during the first several days of voyages, and Klein et al (2010) observed some increases in diatom abundances, suggesting possible reproduction in ballast tanks.…”

“…Regional differences in abundance may be partially explained by mortality of species due to voyage length (Klein et al 2010;Seiden et al 2011;Simard et al 2011), with voyages to the Pacific region being nearly twice as long as those to the Atlantic region. In addition, Seiden et al (2011) reported regrowth of bacteria during the first several days of voyages, and Klein et al (2010) observed some increases in diatom abundances, suggesting possible reproduction in ballast tanks. However, both authors reported a decline in abundance of taxa at the end of voyages, possibly related to fluctuating and inhospitable conditions in ballast tanks.…”

“…mL 21 for species , 50 mm in maximum and $ 10 mm in minimum dimension, in addition to limits for indicator bacteria (IMO 2004). As species may respond differently to changes in environmental conditions during transport, such as temperature, salinity, phosphate concentration, and dissolved oxygen concentration (Klein et al 2010;Seiden et al 2011), propagule pressure and colonization pressure-and invasion risk in consequence-could be altered by voyage characteristics including voyage length and ship pathway (i.e., trans-pacific, trans-atlantic, coastalpacific, or coastal-atlantic).…”

PENGARUH SIMULASI TRANSPORTASI KAPAL PADA KERENTANAN KERANG HIJAU Perna viridis TERHADAP HYPOSALINITY

“…Di sisi lain, perbedaan salinitas juga relevan terhadap organisme bentik dan organisme perairan dangkal yang sering mendapat masukan air tawar dari daratan. Organisme yang menempel di lambung kapal dapat terbawa hingga pada lintang yang berbeda sehingga berpengaruh pada perbedaan salinitas juga (Schneider, 2008;Seiden et al, 2011).…”