Introduction Noise pollution is a major stressor in the marine environment; however, responses of economically and ecologically important invertebrates, such as oysters, are largely unknown. Methods Under laboratory conditions, we measured acute behavioral and physiological responses of eastern oysters ( Crassostrea virginica) to sound treatments mimicking human activity in the environment. Results Oysters immediately reduced their valve gape under simulated pile driving sound, but not drilling or boating sound. Pile-driving sound also reduced adductor muscle glycogen, but not triglyceride. None of the sound treatments affected longer-term (12 hours) valve activity levels after the administration of sounds. Interestingly, neither acute nor longer-term valve gaping responses were correlated with glycogen content on the individual level, suggesting that the observed behavioral responses to sound were not mechanistically driven by energetic physiology. Discussion Our results suggest that C. virginica responds to some, but not all, anthropogenic sounds. Future studies assessing downstream effects on growth, reproduction, and survival in the wild are needed to better understand the effects of anthropogenic sounds on oyster populations and the biological communities they support.

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium- and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement.

Aquatic invasive species (AIS) represent a significant threat to aquatic ecosystems, and early detection is a crucial step in mitigating risks of establishment and spread. In this study, we designed and/or optimized species-specific qPCR assays for 9 marine invertebrates considered invasive in Eastern Canada for use in conjunction with environmental DNA (eDNA) sampling. All qPCR assays showed high analytical sensitivity with theoretical limit of detection (LOD) ranging from 0.045 to 9.24 picogram (pg) of DNA. Comparison of two eDNA water sampling methods showed an increased detection sensitivity using the grab sample approach. eDNA AIS detections were also compared to results obtained using a traditional in situ biofouling monitoring method (i.e., biofouling monitoring lines), and a high concordance between the two was observed. We also determined temporal variability in the amount of DNA found in the environment for some of the targeted AIS, which will help target seasonal monitoring efforts. The results provided herein clearly demonstrate the usefulness of including eDNA for early AIS detection in ongoing monitoring, rapid response investigations and mitigation/eradication efforts.

AbstractGenomic studies of invasive species can reveal both invasive pathways and functional differences underpinning patterns of colonization success. The European green crab (Carcinus maenas) was initially introduced to eastern North America nearly 200 years ago where it expanded northwards to eastern Nova Scotia. A subsequent invasion to Nova Scotia from a northern European source allowed further range expansion, providing a unique opportunity to study the invasion genomics of a species with multiple invasions. Here, we use restriction‐site‐associated DNA sequencing‐derived SNPs to explore fine‐scale genomewide differentiation between these two invasions. We identified 9137 loci from green crab sampled from 11 locations along eastern North America and compared spatial variation to mitochondrial COI sequence variation used previously to characterize these invasions. Overall spatial divergence among invasions was high (pairwise FST ~0.001 to 0.15) and spread across many loci, with a mean FST ~0.052 and 52% of loci examined characterized by FST values >0.05. The majority of the most divergent loci (i.e., outliers, ~1.2%) displayed latitudinal clines in allele frequency highlighting extensive genomic divergence among the invasions. Discriminant analysis of principal components (both neutral and outlier loci) clearly resolved the two invasions spatially and was highly correlated with mitochondrial divergence. Our results reveal extensive cryptic intraspecific genomic diversity associated with differing patterns of colonization success and demonstrates clear utility for genomic approaches to delineating the distribution and colonization success of aquatic invasive species.

In eastern Canada, the initial suspected discovery of the non-indigenous colonial ascidian Diplosoma listerianum in Quebec was followed by species identification and increased awareness for its detection in the neighbouring provinces of Nova Scotia and Prince Edward Island. A phylogenetic analysis was conducted based on sequences generated from the 18S ribosomal DNA gene isolated from tissues of two Canadian samples (Quebec and Nova Scotia) and samples from several species belonging to the Diplosoma genus, which confirmed the species identity of the eastern Canadian specimens. Colonies of D. listerianum found in Quebec (2008) and Nova Scotia (2012) are currently the only tissue records of this species in eastern Canada. Water samples of concentrated plankton collected in Quebec (2010 and 2011) and in Prince Edward Island (2011) tested PCR positive for D. listerianum DNA, but colonies were not observed concurrently. As a case study for early detection, this paper documents how D. listerianum was detected in eastern Canada by different groups (government monitoring, academic research) and with different methods (dive surveys, genetic analysis of water samples, collector plates). This case study suggests that the co-operation between groups and the breadth of the methods used contributed to the early detection of this species in three eastern Canadian provinces. In particular, we show that (i) partnerships between government, academia, and industry, (ii) a national capacity for species-specific molecular detection tools, and (iii) the recognition that the effectiveness and limitations of different monitoring methods may be site-specific can have positive early detection and monitoring outcomes.

Following anecdotal reports of tunicates on the carapaces of rock crab (Cancer irroratus) and American lobster (Homarus americanus), we evaluated the role of these species and northern lady crab Ovalipes ocellatus as natural vectors for the spread of invasive tunicates in the southern Gulf of St. Lawrence. Several hundred adult specimens of crabs and lobster from two tunicateinfested estuaries and Northumberland Strait were examined for epibionts. Small patches of Botrylloides violaceus were found on rock crabs examined from Savage Harbour and a small colony of Botryllus schlosseri was found on one lobster from St. Peters Bay. Lobster and lady crab collected in Northumberland Strait had no attached colonial tunicates but small sea grapes (Molgula sp.) were found attached on the underside of 5.5% of the rock crab and on 2.5% of lobster collected in Northumberland Strait in August 2006. Lobster and rock crab clearly represent a vector for the spread of invasive tunicates regionally and wherever living crustaceans are shipped globally.

The cladoceran, Penilia avirostris, was collected in zooplankton samples from Colville Bay, Prince Edward Island (46 degrees N 62 degrees W) in the southern Gulf of St. Lawrence, in the autumns of 2000 and 2001. This is the first report of the species from Canadian waters, and represents a northeasterly range extension of 5 degrees of latitude or approximately 1130 km. The most likely vector for this introduction was ballast water from international shipping. In October 2000, when the species was first detected, the observed population density of 0.073 individuals/m(3) represented less than 0.3% of the zooplankton community. One year later, the density was 27.5 individuals/m(3) and Pendia was the fourth most abundant zooplankter, accounting for 8% of the community. All females were parthenogenetic, but 0.3% of the individuals collected in 2001 were males, implying that sexual reproduction by resting eggs could occur in this population. The size of males (mean length 684 mu m, range 591-773 mu m) and parthenogenetic females (mean 840 mu m, range 409-1000 mu m) was similar to those reported in the literature. Three percent of the females were juveniles, and a reproducing population appeared to be well established.