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Population attenuation in zooplankton communities during transoceanic transfer in ballast water

View Article: PubMed Central - PubMed

ABSTRACT

Successful biological invasion requires introduction of a viable population of a nonindigenous species (NIS). Rarely have ecologists assessed changes in populations while entrained in invasion pathways. Here, we investigate how zooplankton communities resident in ballast water change during transoceanic voyages. We used next‐generation sequencing technology to sequence a nuclear small subunit ribosomal DNA fragment of zooplankton from ballast water during initial, middle, and final segments as a vessel transited between Canada and Brazil. Operational taxonomic unit (OTU) diversity decreased as voyage duration increased, indicating loss of community‐based genetic diversity and development of bottlenecks for zooplankton taxa prior to discharge of ballast water. On average, we observed 47, 26, and 24 OTUs in initial, middle, and final samples, respectively. Moreover, a comparison of genetic diversity within taxa indicated likely attenuation of OTUs in final relative to initial samples. Abundance of the most common taxa (copepods) declined in all final relative to initial samples. Some taxa (e.g., Copepoda) were represented by a high number of OTUs throughout the voyage, and thus had a high level of intraspecific genetic variation. It is not clear whether genotypes that were most successful in surviving transit in ballast water will be the most successful upon introduction to novel environments. This study highlights that population bottlenecks may be common prior to introduction of NIS to new ecosystems.

No MeSH data available.


Average (±SD) number of OTUs (A) and average (±SD) number of sequences (B) obtained from all initial (black bar), middle (gray bar), and final (white bar) samples. Groups that are significantly different are not joined by the same line above the bars.
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ece32349-fig-0003: Average (±SD) number of OTUs (A) and average (±SD) number of sequences (B) obtained from all initial (black bar), middle (gray bar), and final (white bar) samples. Groups that are significantly different are not joined by the same line above the bars.

Mentions: The number of OTUs decreased from the start to the end of each voyage, suggesting zooplankton die‐off in ballast tanks (Fig. 2). The mean number of OTUs recovered from initial samples of all three voyages differed significantly from that found in the middle and final samples (ANOVA, F = 15.17, P = 0.001) (Fig. 3A), while trip differences (i.e., block effect) were not significant (F = 0.83, P = 0.574) (Table S2). Conversely, the mean number of sequences obtained from initial, middle, and final samples did not differ significantly (ANOVA, F = 1.19, P = 0.345), although a significant block effect was observed (F = 4.80, P = 0.015) (Table S2). These results indicate that differences in OTU depletion rate over time were not due to the number of recovered sequences (Fig. 3B).


Population attenuation in zooplankton communities during transoceanic transfer in ballast water
Average (±SD) number of OTUs (A) and average (±SD) number of sequences (B) obtained from all initial (black bar), middle (gray bar), and final (white bar) samples. Groups that are significantly different are not joined by the same line above the bars.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5016640&req=5

ece32349-fig-0003: Average (±SD) number of OTUs (A) and average (±SD) number of sequences (B) obtained from all initial (black bar), middle (gray bar), and final (white bar) samples. Groups that are significantly different are not joined by the same line above the bars.
Mentions: The number of OTUs decreased from the start to the end of each voyage, suggesting zooplankton die‐off in ballast tanks (Fig. 2). The mean number of OTUs recovered from initial samples of all three voyages differed significantly from that found in the middle and final samples (ANOVA, F = 15.17, P = 0.001) (Fig. 3A), while trip differences (i.e., block effect) were not significant (F = 0.83, P = 0.574) (Table S2). Conversely, the mean number of sequences obtained from initial, middle, and final samples did not differ significantly (ANOVA, F = 1.19, P = 0.345), although a significant block effect was observed (F = 4.80, P = 0.015) (Table S2). These results indicate that differences in OTU depletion rate over time were not due to the number of recovered sequences (Fig. 3B).

View Article: PubMed Central - PubMed

ABSTRACT

Successful biological invasion requires introduction of a viable population of a nonindigenous species (NIS). Rarely have ecologists assessed changes in populations while entrained in invasion pathways. Here, we investigate how zooplankton communities resident in ballast water change during transoceanic voyages. We used next‐generation sequencing technology to sequence a nuclear small subunit ribosomal DNA fragment of zooplankton from ballast water during initial, middle, and final segments as a vessel transited between Canada and Brazil. Operational taxonomic unit (OTU) diversity decreased as voyage duration increased, indicating loss of community‐based genetic diversity and development of bottlenecks for zooplankton taxa prior to discharge of ballast water. On average, we observed 47, 26, and 24 OTUs in initial, middle, and final samples, respectively. Moreover, a comparison of genetic diversity within taxa indicated likely attenuation of OTUs in final relative to initial samples. Abundance of the most common taxa (copepods) declined in all final relative to initial samples. Some taxa (e.g., Copepoda) were represented by a high number of OTUs throughout the voyage, and thus had a high level of intraspecific genetic variation. It is not clear whether genotypes that were most successful in surviving transit in ballast water will be the most successful upon introduction to novel environments. This study highlights that population bottlenecks may be common prior to introduction of NIS to new ecosystems.

No MeSH data available.