Richness-abundance relationships for zooplankton in ballast water: temperate versus Arctic comparisons

Species richness and abundance are two commonly measured parameters used to characterize invasion risk associated with transport vectors, especially those capable of transferring large species assemblages. Understanding the relationship between these two variables can further improve our ability to predict future invasions by identifying conditions where high-risk (i.e. species-rich or high abundance or both) and low-risk (i.e. species-poor and low abundance) introduction events are expected. While ballast water is one of the best characterized transport vectors of aquatic non-indigenous species, very few studies have assessed its magnitude at high latitudes. We assessed the arrival potential of zooplankton via ballast water in the Canadian Arctic by examining species richness, total abundance, and the relationship between the two parameters for zooplankton in ships from Europe destined for the Arctic, in comparison with the same parameters for ships bound for Atlantic Canada and the Great Lakes. In addition, we examined whether species richness and/or total abundance were influenced by temperature change and/or ballast water age for each shipping route. We found that species richness and total abundance for Arctic and Great Lakes ships were significantly lower than those for Atlantic ships. Differences in species richness and total abundance for ships utilizing different shipping routes were mostly related to ballast water age. A significant species richness–total abundance relationship for Arctic and Great Lakes ships suggests that these parameters decreased proportionately as ballast water aged. In contrast, the absence of such a relationship for Atlantic ships suggests that decreases in total abundance were accompanied by little to no reduction in species richness. Collectively, our results indicate that the arrival potential of zooplankton in ballast water of Arctic ships may be lower than or similar to that of Atlantic and Great Lakes ships, respectively

Evaluating the response of freshwater organisms to vital staining

The unintentional introduction of nonindigenous species by ballast water discharge is one of the greatest threats to biodiversity in freshwater systems. Proposed international regulations for ballast water management will require enumeration of viable plankton in ballast water. In this study we analyze the efficacy of vital stains in determining viability of freshwater taxa. The efficacy of vital stains fluorescein diacetate (FDA) and FDA+5-chloromethylfluorescein diacetate (CMFDA) was evaluated with freshwater macroinvertebrates, zooplankton, and phytoplankton. Macroinvertebrates were cultured in laboratory, while plankton were collected from Hamilton Harbour and ballast tanks of commercial vessels. Organisms were subjected to various treatments (i.e., heat, NaClO, and NaOH) to establish efficacy of stains for viable and non-viable organisms. No significant difference in accuracy rate was found between stains, regardless of treatment, within groups of organisms, indicating that the addition of CMFDA is superfluous in the sample region studied. False positive errors, in which dead organisms fluoresced similarly to live organisms, occurred in most groups and were significantly different between test groups. False positive error rates were 2.3% for phytoplankton, 20% for ballast water zooplankton, 35% for Hamilton Harbour zooplankton and 47% for macroinvertebrates. Response to stains varied between taxonomic groups. Low (< 10%) false positive error rates were observed with phytoplankton, soft-bodied rotifers, oligochaetes, and Bosmina spp., while rates between 20% and 50% were observed for Daphnia spp., Hexagenia sp., and Chironomus riparius. False positive rates of copepods, Hyalella azteca, and Hemimysis anomala were between 70% and 100%. The FDA/FDA+CMFDA vital staining methods provide useful tools for viability analysis of freshwater phytoplankton, soft-bodied invertebrates and zooplankton, and may be used for viability analysis of the ≥ 10 µm to < 50 µm size fraction in compliance testing of ballast water. However, viability analysis of larger freshwater crustaceans with vital stains should be undertaken with caution

Evaluating efficacy of a ballast water filtration system for reducing spread of aquatic species in freshwater ecosystems

Biological invasions by non-indigenous species are considered a leading threat to biodiversity, with prevention being a key management strategy. Consequently, numerous commercial ballast water treatment systems have been, or are being, developed to prevent future aquatic invasions. However, most treatment systems are being designed for the many vessels undertaking long transoceanic voyages in marine waters rather than the relatively few vessels operating on short voyages in freshwater, such as those in the Laurentian Great Lakes. Here we conduct testing of the biological efficacy of a 40 µm ballast water filtration unit through shipboard trials. We test the hypotheses that i) filtration will significantly reduce abundance of zooplankton greater than 50 µm in size but not phytoplankton 10 to 50 µm in size; ii) filtration will reduce zooplankton abundances in ballast water below International Maritime Organization discharge standards, but not those of phytoplankton; and iii) filtration will alter the community composition of zooplankton, non-randomly reducing invasion risk of larger taxa. During the summer of 2012, three shipboard trials were conducted. Ballast water samples were collected using a before-after experimental design. Our study showed that filtration significantly reduced abundance of copepods and cladocerans, but not of juvenile dreissenid veligers and rotifers. Contrary to our expectation, phytoplankton densities were also significantly lower after the treatment. Overall, ballast water treated during our tests would not meet proposed international discharge standards. Filtration altered relative abundance of zooplankton, but did not reduce introduction risk of any taxonomic group due to the small juvenile stages and dormant eggs which passed through the treatment. While we do not rule out filtration as a ballast water treatment option for zooplankton in the future, our tests indicate further development is required for meaningful reduction of invasion risk

Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) in the Great Lakes: Playing with fire?

The Laurentian Great Lakes have been successfully invaded by at least 182 nonindigenous species. Here we report on two new species, water hyacinth Eichhornia crassipes and water lettuce Pistia stratiotes, that were found at a number of locations in Lake St. Clair and Detroit River during autumn 2010. Both species are commonly sold in the water garden and aquarium trade in southern Ontario and elsewhere. While it is not clear whether these species are established or can establish in the Great Lakes, the historic assumption that neither of these subtropical to tropical plants pose an invasion risk must be questioned in the light of changing environmental conditions associated with climate warming that may render Great Lakes\u27 habitats more suitable for these species and increase the likelihood of their successful establishment. © 2011 The Author(s)

Separation strategies for invertebrate dormant stages contained in sediment

To accurately assess community composition of invertebrates, both active and dormant life stages should be considered. Dormant stages are typically produced as a strategy to overcome inhospitable environmental conditions and can also facilitate species dispersal. While they often sink and accumulate in sediment of natural habitats forming ‘egg banks,’ dormant stages are also found in the sediments accumulated in ships’ ballast tanks. Recent studies have used 2 different methods to separate dormant stages from ballast sediment to assess invasion risk associated with ballast tanks: the colloidal silica sol Ludox HS 40 and sugar flotation (i.e. the Onbé-Marcus method). It has been assumed that the Ludox HS 40 method is most effective for separation but reduces dormant stage viability whereas sugar flotation has lower separation efficacy but higher resulting viability. We conducted a comparative assessment of the 2 methods by separating dormant stages from 160 ballast sediments and examining resulting abundance counts, hatching results, DNA extractions and PCR amplifications. We found no difference in the results between the methods. The financial cost of sugar flotation is lower than that of Ludox HS 40, and costs can be further reduced by using only 1 method instead of both due to lower labour costs, particularly for a large number of samples

A retrospective comparative outcome analysis following systemic therapy in Mycosis fungoides and Sezary syndrome

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134845/1/ajh24564_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134845/2/ajh24564.pd

Prioritising surveillance for alien organisms transported as stowaways on ships travelling to South Africa

The global shipping network facilitates the transportation and introduction of marine and terrestrial organisms to regions where they are not native, and some of these organisms become invasive. South Africa was used as a case study to evaluate the potential for shipping to contribute to the introduction and establishment of marine and terrestrial alien species (i.e. establishment debt) and to assess how this varies across shipping routes and seasons. As a proxy for the number of species introduced (i.e. 'colonisation pressure') shipping movement data were used to determine, for each season, the number of ships that visited South African ports from foreign ports and the number of days travelled between ports. Seasonal marine and terrestrial environmental similarity between South African and foreign ports was then used to estimate the likelihood that introduced species would establish. These data were used to determine the seasonal relative contribution of shipping routes to South Africa's marine and terrestrial establishment debt. Additionally, distribution data were used to identify marine and terrestrial species that are known to be invasive elsewhere and which might be introduced to each South African port through shipping routes that have a high relative contribution to establishment debt. Shipping routes from Asian ports, especially Singapore, have a particularly high relative contribution to South Africa's establishment debt, while among South African ports, Durban has the highest risk of being invaded. There was seasonal variation in the shipping routes that have a high relative contribution to the establishment debt of the South African ports. The presented method provides a simple way to prioritise surveillance effort and our results indicate that, for South Africa, port-specific prevention strategies should be developed, a large portion of the available resources should be allocated to Durban, and seasonal variations and their consequences for prevention strategies should be explored further. (Résumé d'auteur

ALAD and APOE polymorphisms are associated with lead and mercury levels in Italian pregnant women and their newborns with adequate nutritional status of zinc and selenium

The impacts of single-nucleotide polymorphisms (SNPs) in ALAD and VDR genes on Pb health effects and/or kinetics are inconclusive at low exposure levels, while studies including APOE SNPs are rare. In this study, we examined the associations of ALAD, VDR and APOE SNPs with exposure biomarkers of Pb and other trace elements (TEs) in Italian pregnant women (N = 873, aged 18–44 years) and their newborns (N = 619) with low-level mixed-element exposure through diet, the environment or endogenously. DNA from maternal peripheral venous blood (mB), sampled during the second and third trimesters, was genotyped for ALAD (rs1800435, rs1805313, rs1139488, rs818708), VDR (rs2228570, rs1544410, rs7975232, rs731236) and APOE (rs429358, rs7421) using TaqMan SNP assays. Personal and lifestyle data and TE levels (mB, maternal plasma, hair and mixed umbilical cord blood [CB]) from the PHIME project were used. Multiple linear regression models, controlling for confounding variables, were performed to test the associations between SNPs and TEs. The geometric means of mB-Pb, mB-Hg, mB-As and mB-Cd (11.0 ng/g, 2.16 ng/g, 1.38 ng/g and 0.31 ng/g, respectively) indicated low exposure levels, whereas maternal plasma Zn and Se (0.72 μg/mL and 78.6 ng/g, respectively) indicated adequate micronutritional status. Variant alleles of ALAD rs1800435 and rs1805313 were negatively associated with mB-Pb levels, whereas a positive association was observed for rs1139488. None of the VDR SNPs or their haplotypes had any association with Pb levels. Regarding APOE, the ϵ4 allele was associated with lower mB-Hg and CB-Hg, while a positive association was found with the ϵ2 allele and CB-Pb when the model included only newborn girls. The observed associations indicate possible modification effects of ALAD and APOE SNPs on Pb or Hg kinetics in women and their newborns with low exposure to non-essential TEs, as well as an adequate nutritional status of Zn and Se

Assessing introduction risk using species' rank-abundance distributions

Mixed-species assemblages are often unintentionally introduced into new ecosystems. Analysing how assemblage structure varies during transport may provide insights into how introduction risk changes before propagules are released. Characterization of introduction risk is typically based on assessments of colonization pressure (CP, the number of species transported) and total propagule pressure (total PP, the total abundance of propagules released) associated with an invasion vector. Generally, invasion potential following introduction increases with greater CP or total PP. Here, we extend these assessments using rank-abundance distributions to examine how CP : total PP relationships change temporally in ballast water of ocean-going ships. Rank-abundance distributions and CP : total PP patterns varied widely between trans-Atlantic and trans-Pacific voyages, with the latter appearing to pose a much lower risk than the former. Responses also differed by taxonomic group, with invertebrates experiencing losses mainly in total PP, while diatoms and dinoflagellates sustained losses mainly in CP. In certain cases, open-ocean ballast water exchange appeared to increase introduction risk by uptake of new species or supplementation of existing ones. Our study demonstrates that rank-abundance distributions provide new insights into the utility of CP and PP in characterizing introduction ris

Relationship between propagule pressure and colonization pressure in invasion ecology: a test with ships' ballast

Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms, we collected 333 ballast water and sediment samples to investigate the relationship between propagule and colonization pressure for a variety of diverse taxonomic groups (diatoms, dinoflagellates and invertebrates). We also reviewed the scientific literature to compare the number of species transported by ships to those reported in nature. Here, we show that even though ships transport nearly entire local communities, a strong relationship between propagule and colonization pressure exists only for dinoflagellates. Our study provides evidence that colonization pressure of invertebrates and diatoms may fluctuate widely irrespective of propagule pressure. We suggest that the lack of correspondence is explained by reduced uptake of invertebrates into the transport vector and the sensitivity of invertebrates and diatoms to selective pressures during transportation. Selection during transportation is initially evident through decreases in propagule pressure, followed by decreased colonization pressure in the most sensitive taxa