Early detection of marine invasive species is key for mitigating and managing their impacts to marine ecosystems and industries. Human divers are considered the gold standard tool for detecting ...marine invasive species, especially when dive teams are familiar with the local biodiversity. However, diver operations can be expensive and dangerous, and are not always practical. Remote operated vehicles (ROVs) can potentially overcome these limitations, but it is unclear how sensitive they are compared to trained divers for detecting pests. We assessed the sensitivity and efficiency of ROVs and divers for detecting marine non-indigenous species (NIS), including the potential for automated detection algorithms to reduce post-processing costs of ROV methods. We show that ROVs can detect comparable assemblages of invasive species as divers, but with lower detection rates (0.2 NIS min
-1
) than divers (0.5 NIS min
-1
) and covered less seafloor than divers per unit time. While small invertebrates (e.g., skeleton shrimp
Caprella mutica
) were more easily detected by divers, the invasive goby
Acentrogobius pflaumii
was only detected by the ROV. We show that implementation of computer vision algorithms can provide accurate identification of larger biofouling organisms and reduce overall survey costs, yet the relative costs of ROV surveys remain almost twice that of diver surveys. We expect that as ROV technologies improve and investment in autonomous and semi-autonomous underwater vehicles increases, much of the current inefficiencies of ROVs will be mitigated, yet practitioners should be aware of limitations in taxonomic resolution and the strengths of specialist diver teams.
The establishment of marine non-indigenous species (NIS) in new locations can degrade environmental, socio-cultural, and economic values. Vessels arriving from international waters are the main ...pathway for the entry of marine NIS, via exposure due to ballast water discharge (hereafter, ballast discharge) and biofouling. We developed a systematic statistical likelihood-based methodology to investigate port-level marine NIS propagule pressure from ballast discharge and biofouling exposure using a combination of techniques, namely
k
-Nearest-Neighbour and random forest algorithms. Vessel characteristics and travel patterns were assessed as candidate predictors. For the ballast discharge analysis, the predictors used for model building were vessel type, dead weight tonnage, and the port of first arrival; the predictors used for the biofouling analysis were days since last antifouling paint, mean vessel speed, dead weight tonnage, and hull niche area. Propagule pressure for both pathways was calculated at a voyage, port and annual level, which were used to establish the relative entry score for each port. The model was applied to a case study for New Zealand. Biosecurity New Zealand has commissioned targeted marine surveillance at selected ports since 2002 to enable early detection of newly arrived marine NIS (Marine High-Risk Site Surveillance, MHRSS). The reported methodology was used to compare contemporary entry likelihoods between New Zealand ports. The results suggested that Tauranga now receives the highest volume of discharged ballast water and has the second most biofouling exposure compared to all other New Zealand ports. Auckland was predicted to receive the highest biofouling mass and was ranked tenth for ballast discharge exposure. Lyttelton, Napier, and New Plymouth also had a high relative ranking for these two pathways. The outputs from this study will inform the refinement of the MHRSS programme, facilitating continued early detection and cost-effective management to support New Zealand’s wider marine biosecurity system. More generally, this paper develops an approach for using statistical models to estimate relative likelihoods of entry of marine NIS.
Early detection is important for successful management of invasive species, but optimising monitoring systems to detect multiple species from different taxonomic groups remains a major challenge. ...Settlement plates are often used to monitor non-indigenous marine species (NIMS) associated with vessel biofouling, but there have been few assessments of their fitness-for-purpose. We deployed arrays of settlement plates (“settlement arrays”) containing combinations of treatments that reflected conditions associated with the vessel transport pathway (i.e., copper based antifouling coatings, shaded habitat) to determine the treatment combinations that maximised NIMS diversity. Horizontal (shaded) treatments preferentially sampled higher NIS diversity than vertical plates. Although plates with copper-based biocides had larger proportions of NIS to indigenous species, they sampled only a subset of NIS diversity. Overall diversity was greatly enhanced through use of multiple treatments, demonstrating benefits of multi-faceted sampling arrays for maximising the potential taxonomic and species richness.
•Selection pressures during marine biofouling transport may be utilised for detection.•Invasive species richness was enhanced by horizontal shaded surfaces.•Tolerance to copper biocides is more prevalent in invasive than indigenous species.•Multi-faceted sampling arrays greatly increase the taxonomic richness sampled.
Aim
The introduction of aquatic non‐indigenous species (ANS) has become a major driver for global changes in species biogeography. We examined spatial patterns and temporal trends of ANS detections ...since 1965 to inform conservation policy and management.
Location
Global.
Methods
We assembled an extensive dataset of first records of detection of ANS (1965–2015) across 49 aquatic ecosystems, including the (a) year of first collection, (b) population status and (c) potential pathway(s) of introduction. Data were analysed at global and regional levels to assess patterns of detection rate, richness and transport pathways.
Results
An annual mean of 43 (±16 SD) primary detections of ANS occurred—one new detection every 8.4 days for 50 years. The global rate of detections was relatively stable during 1965–1995, but increased rapidly after this time, peaking at roughly 66 primary detections per year during 2005–2010 and then declining marginally. Detection rates were variable within and across regions through time. Arthropods, molluscs and fishes were the most frequently reported ANS. Most ANS were likely introduced as stowaways in ships’ ballast water or biofouling, although direct evidence is typically absent.
Main conclusions
This synthesis highlights the magnitude of recent ANS detections, yet almost certainly represents an underestimate as many ANS go unreported due to limited search effort and diminishing taxonomic expertise. Temporal rates of detection are also confounded by reporting lags, likely contributing to the lower detection rate observed in recent years. There is a critical need to implement standardized, repeated methods across regions and taxa to improve the quality of global‐scale comparisons and sustain core measures over longer time‐scales. It will be fundamental to fill in knowledge gaps given that invasion data representing broad regions of the world's oceans are not yet readily available and to maintain knowledge pipelines for adaptive management.
The Marine Biosecurity Porthole was created in 2010 as a collaboration between New Zealand’s Ministry for Primary Industries (MPI) and the National Institute for Water and Atmospheric Research (NIWA) ...to provide greater public access to information and data on non-indigenous marine species (NIMS) in New Zealand. The porthole is primarily an interactive mapping application that allows verified observations on the distribution of NIMS within New Zealand to be displayed. It draws upon data compiled from a range of funded surveys for NIMS, including a series of port biological baseline surveys and a continuing programme of targeted surveillance for high risk marine pests in major shipping ports and marinas. The data also include records from specimens reported via the passive surveillance system and identified through the Marine Invasives Taxonomic Service (MITS), a taxonomic clearing house service for suspect marine organisms, and observations of NIMS made through taxonomic and ecological research undertaken by NIWA. It currently contains information for over 3,600 native, cryptogenic and non-indigenous marine species with links to over 155,000 individual distribution records. Additional features include a searchable catalogue of relevant reports, papers and information about NIMS and on the surveys undertaken to obtain the data. The design and functionality of the portal have been refreshed to provide a better overall experience for users. New features will allow greater filtering and selection of distribution data, more content on NIMS within New Zealand, and connections to social media.
The current explanation for the absence, or low abundance, of filter-feeding invertebrates from some rocky shores is that because of local variation in nearshore oceanographic conditions, larvae do ...not arrive in sufficient numbers to establish populations. One putative consequence of this is that macroalgae are able to establish dominance in areas where filter-feeders (especially mussels) do not recruit well. While macroalgae have been transplanted to mussel-dominated shores with varying success, the survival, growth and reproduction of transplanted mussels has not been tested in areas dominated by macroalgae. To determine specifically what tips the balance between shores dominated by filter-feeding invertebrates and those dominated by macroalgae, I monitored the recruitment of intertidal mussels at four sites on the Kaikoura coast: two with mussels present and two algal-dominated. No significant differences in mussel recruitment rates were found between habitats and recruitment intensity at all sites was found to be very low. Recruitment limitation is not the reason for the absence of mussels from algal dominated shores but some form of limitation does occur to reduce the number of arriving mussels. Predation effects were examined by transplanting juvenile mussels into caged, uncaged and control treatments. No significant differences in predation rates between habitats were found and transplanted mussels in open cages at all sites were removed within 3 days. Mobile fish predators appeared to be the most likely cause of this intense predation. Growth of transplanted mussels into algal and mussel habitats was found to be significantly different. Mussels grew faster in mussel dominated habitats and after 6 months in algal dominated habitats, all mussels had died. The outcome of these experiments indicates that there is a close relationship between recruitment, survival and growth which tips the balance and allows the existence of mussel beds along the Kaikoura coastline.
Thesis (M. Sc.)--University of Canterbury, 2006.
Typescript (photocopy). Includes bibliographical references (leaves 71-79). Also available via the World Wide Web.
The current explanation for the absence, or low abundance, of filter-feeding invertebrates from some rocky shores is that because of local variation in nearshore oceanographic conditions, larvae do ...not arrive in sufficient numbers to establish populations. One putative consequence of this is that macroalgae are able to establish dominance in areas where filter-feeders (especially mussels) do not recruit well. While macroalgae have been transplanted to mussel-dominated shores with varying success, the survival, growth and reproduction of transplanted mussels has not been tested in areas dominated by macroalgae. To determine specifically what tips the balance between shores dominated by filter-feeding invertebrates and those dominated by macroalgae, I monitored the recruitment of intertidal mussels at four sites on the Kaikoura coast: two with mussels present and two algal-dominated. No significant differences in mussel recruitment rates were found between habitats and recruitment intensity at all sites was found to be very low. Recruitment limitation is not the reason for the absence of mussels from algal dominated shores but some form of limitation does occur to reduce the number of arriving mussels. Predation effects were examined by transplanting juvenile mussels into caged, uncaged and control treatments. No significant differences in predation rates between habitats were found and transplanted mussels in open cages at all sites were removed within 3 days. Mobile fish predators appeared to be the most likely cause of this intense predation. Growth of transplanted mussels into algal and mussel habitats was found to be significantly different. Mussels grew faster in mussel dominated habitats and after 6 months in algal dominated habitats, all mussels had died. The outcome of these experiments indicates that there is a close relationship between recruitment, survival and growth which tips the balance and allows the existence of mussel beds along the Kaikoura coastline.
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