Adverse impacts of marine litter is documented on >1400 species, including marine megafauna (fish, birds, sea turtles and mammals). The primary impacts include ingestion and entanglement, and there is increasing concern about chemical contamination via ingestion. Numerous survey approaches and monitoring programs have been developed and implemented around the world. They may aim to provide data about parameters such as species distribution and interactions with anthropogenic activities. During the Sixth International Marine Debris Conference, a session was dedicated to the tools and constraints in monitoring interactions between litter and megafauna. In the present paper, we summarize 7 case studies which discuss entanglement and ingestion including macro- and micro-debris in several taxa and across multiple geographic regions. We then discusses the importance of tools and standardizing methods for assessment and management purposes, in the context of international environmental policies and marine litter strategies.
Marine carbon dioxide (CO2) system data has been collected from December 2014 to June 2018 in the Northern Salish Sea (NSS; British Columbia, Canada) and consisted of continuous measurements at two sites as well as spatially- and seasonally distributed discrete seawater samples. The array of CO2 observing activities included high-resolution CO2 partial pressure (pCO2) and pHT (total scale) measurements made at the Hakai Institute’s Quadra Island Field Station (QIFS) and from an Environment Canada weather buoy, respectively, as well as discrete seawater measurements of pCO2 and total dissolved inorganic carbon (TCO2) obtained during a number of field campaigns. A relationship between NSS alkalinity and salinity was developed with the discrete datasets and used with the continuous measurements to highly resolve the marine CO2 system. Collectively, these datasets provided insights into the seasonality in this historically under-sampled region and detail the area’s tendency for aragonite saturation state (Ωarag) to be at non-corrosive levels (i.e., Ωarag > 1) only in the upper water column during spring and summer months. This depth zone and time period of reprieve can be periodically interrupted by strong northwesterly winds that drive short-lived (∼1 week) episodes of high-pCO2, low-pH, and low-Ωarag conditions throughout the region. Interannual variability in summertime conditions was evident and linked to reduced northwesterly winds and increased stratification. Anthropogenic CO2 in NSS surface water was estimated using data from 2017 combined with the global atmospheric CO2 forcing for the period 1765 to 2100, and projected a mean value of 49 ± 5 μmol kg-1 for 2018. The estimated trend in anthropogenic CO2 was further used to assess the evolution of Ωarag and pHT levels in NSS surface water, and revealed that wintertime corrosive Ωaragconditions were likely absent pre-1900. The percent of the year spent above Ωarag = 1 has dropped from ∼98% in 1900 to ∼60% by 2018. Over the coming decades, winter pHT and spring and summer Ωarag are projected to decline to conditions below identified biological thresholds for select vulnerable species.
Designation of large expanses of the ocean as Marine Protected Area (MPA) is increasingly advocated and realised. The effectiveness of such MPAs, however, requires improvements to vessel monitoring and enforcement capability. In 2014 commercial fishing was excluded from the Ascension Island Exclusive Economic Zone (EEZ). In 2015, through updated regulations, a licenced fishery re-opened in the northern half of the EEZ while the southern half remained closed. To assess compliance with these closures and regulations, several promising satellite technologies (Satellite Automatic Identification System (S-AIS), Synthetic Aperture Radar (SAR), Vessel Monitoring System (VMS) of two vessels), were trialled alongside at-sea patrols. Use of SAR enabled assessment of ‘dark’ (non-AIS transmitting) vessels, the scope of whose activities are hardest to gauge. The high level of compliance with regulations observed, suggests the MPA may prove effective, yet a need for vigilance remains. Vessels aggregate near the EEZ border and a quarter of vessels tracked across three years exhibited S-AIS transmission gaps and present a heightened compliance risk. Use of remote, rather than local, expertise and infrastructure provide a blue-print and economies of scalefor replicating monitoring across similarly sized MPAs; particularly for large (>~ 25 m) vessels with metallic superstructures conducive to SAR detection. Funding ongoing monitoring in Ascension is challenged by current levels of license uptake, which provides insufficient offsetting revenue. Satellite-derived intelligence, can be used to set risk thresholds and trigger detailed investigations. Planning long-term monitoring must, however, incorporate adequate resources for follow-up, through patrols and correspondence with flag-states and fisheries management organisations.
Acoustic tagging is typically used to gather data on the spatial ecology of diverse marine taxa, informing questions about spatio-temporal attributes such as residency and home range, but detection data may also reveal unanticipated insights. Many species demonstrate predictable site fidelity, and so a sudden cessation of detections for multiple individuals may be evidence of an atypical event. During 2013 and 2014, we acoustically tagged 47 grey reef sharks (Carcharhinus amblyrhynchos) and 48 silvertip sharks (Carcharhinus albimarginatus) near reefs in the British Indian Ocean Territory (BIOT) Marine Protected Area (MPA). From March 2013 to November 2014 inclusive, tags were ‘lost’, i.e. permanently ceased to be detected within the monitoring area, at an average rate of 2.6 ± 1.0 tags per month. Between 1 and 10 December 2014, detection data suggest the near-simultaneous loss of 15 of the remaining 43 active tagged sharks, a monthly loss rate over five times higher than during the previous 21 months. Between 4 and 14 December of 2014, the BIOT patrol vessel encountered 17 vessels engaged in suspected illegal fishing in the northern BIOT MPA; such sightings averaged one per month during the previous 8 months. Two of these vessels were arrested with a total of 359 sharks on board, of which grey reef and silvertip sharks constituted 47% by number. The unusual and coincident peaks in tag loss and vessel sightings, and the catch composition of the arrested vessels, suggest illegal fishing as a plausible explanation for the unusual pattern in our detection data. A Cox proportional hazards model found that the presence of fishing vessels increased the risk of tag loss by a factor of 6.0 (95% CI 2.6–14.0, p < 0.001). Based on the number of vessels sighted and the average number of sharks on vessels arrested in BIOT during 2014, we conservatively estimate that over 2000 sharks may have been removed during the suspected fishing event. Based on average catch compositions, over 1000 would have been grey reef and silvertip sharks. Assuming a closed population mark-recapture model, over one-third of the locally resident reef sharks may have been removed from the monitoring area. The data suggest that even sporadic fishing events may have a marked impact on local reef shark populations, but also demonstrate the potential of electronic tagging a tool for detecting illegal or otherwise unreported fishing activity.
Increasingly studies are reporting sudden and dramatic changes in the structure and function of communities or ecosystems. The prevalence of these reports demonstrates the importance for management of being able to detect whether these have happened and, preferably, whether they are likely to occur. Ecological theory provides the rationale for why such changes occur and a variety of statistical indicators of approach that have generic properties have been developed. However, whether the theory has successfully translated into monitoring programmes is unknown. We searched the literature for guidelines that would drive design of monitoring programmes able to detect past and approaching tipping points and analysed marine monitoring programmes in New Zealand. We found very few guidelines in the ecological, environmental or monitoring literature, although both simulation and marine empirical studies suggest that within-year sampling increases the likelihood of detecting approaching tipping points. The combination of the need to monitor both small and medium scale temporal dynamics of multiple variables to detect tipping points meant that few marine monitoring programmes in New Zealand were fit for that purpose. Interestingly, we found many marine examples of studies detecting past and approaching TP with fewer data than was common in the theoretical literature. We, therefore, suggest that utilizing ecological knowledge is of paramount importance in designing and analyzing time-series monitoring for tipping points and increasing the certainty for short-term or infrequent datasets of whether a tipping point has occurred. As monitoring plays an important role in management of tipping points by providing supporting information for other locations about when and why a tipping point may occur, we believe that monitoring for tipping points should be promoted.
Nesting sea turtles appear to avoid brightly lit beaches and often turn back to sea prematurely when exposed to artificial light. Observations and experiments have noted that nesting turtles prefer darker areas where buildings and high dunes act as light barriers. As a result, sea turtles often nest on darker beaches, creating spatial concentrations of nests. Artificial nighttime light, or light pollution, has been quantified using a variety of methods. However, it has proven challenging to make accurate measurements of ambient light at fine scales and on smaller nesting beaches. Additionally, light has traditionally been measured from stationary tripods perpendicular to beach vegetation, disregarding the point of view of a nesting sea turtle. In the present study, nighttime ambient light conditions were assessed on three beaches in central North Carolina: a developed coastline of a barrier island, a nearby State Park on the same barrier island comprised of protected and undeveloped land, and a completely uninhabited wilderness on an adjacent barrier island in the Cape Lookout National Seashore. Using an autonomous terrestrial rover, high resolution light measurements (mag/arcsec2) were collected every minute with two ambient light sensors along transects on each beach. Spatial comparisons between ambient light and nesting density at and between these locations reveal that highest densities of nests occur in regions with lowest light levels, supporting the hypothesis that light pollution from coastal development may influence turtle nesting distribution. These results can be used to support ongoing management strategies to mitigate this pressing conservation issue.
Over 25 years ago the first satellite tracking studies of sea turtles were published. The technology and attachment methods have now come of age with long-term tracks over a year being commonplace and the ability to relay high resolution GPS locations via the Argos satellite system along with behavioral (e.g., diving and activity) and environmental (e.g., temperature) data. Early studies focused on breeding females because they come ashore to nest, allowing individuals to be restrained relatively easily for tag attachment. However, today the development of methods for the capture of turtles at sea are increasingly allowing studies on both adult male turtles as well as immature turtles as small as 11 cm carapace length. Here we review the extent of work after many thousands of individual turtles have been tracked. We consider the state-of-the-art equipment for satellite tracking turtles and how this technology is being used to tackle key questions. We highlight some of the emerging opportunities arising from improved spatial resolution of tracking, increased robustness and miniaturization of tags as well as increasing availability of environmental data. We highlight the huge potential for big-data studies to make use of the thousands of tracks that exist, although we discuss the long-standing challenges surrounding data accessibility.
Citizen science is an innovative approach that relies on non-specialists to monitor species and ecosystems over long time periods and vast geographical areas. Citizen science has been used extensively in marine science to monitor endangered species such as sharks and marine turtles, coral reefs and their associated fish species, marine mammals, invasive species and, more recently, coral bleaching and marine litter. Engaging people over the long term can be challenging but using social media, gamification, and emphasizing the value of volunteer contributions through data sharing, can help to keep communities motivated. In the Red Sea, there is enormous potential for using citizen science in monitoring endangered species and ecosystems due to the presence of a fleet of safari boats and dive centres going to sea daily. Engaging with this sector and creating long lasting partnerships for data collection through simple protocols could be a winning approach to obtain important information from remote areas and/or on rare species. In this chapter, we present the preliminary results of a citizen science program targeting marine turtles in their feeding grounds in the Egyptian Red Sea waters that was conducted from 2011 to 2013. During the study period 2,448 surveys were completed at 157 sites and included a total of 1,038 sightings of turtles. The most commonly observed species were hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles; however, rarer species, such as loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) turtles were also recorded. Among the sites that were monitored, some were considered as important for turtles (i.e., had a high probability of observing a turtle), while in others, turtles were not observed despite carrying out multiple surveys. Participants reported turtles of various sizes and ages with adults and sub-adults being the predominant observed age class. The presence of adults seemed to be related to the nesting season (May–September), which was also when the survey effort was higher. Adult male turtles were observed on various occasions, providing important input on their whereabouts during nesting and non-nesting seasons. Finally, participants detected behaviour that had not been previously described in the region, such as courting and mating. Results from TurtleWatch Egypt provided new insight in our knowledge of marine turtles in the Red Sea, especially from the largely under-studied feeding grounds.
Monitoring marine activities has always been a difficult task due to the vastness of the world's oceans. This inability to properly monitor both high seas and territorial zones alike has meant that illegal activities at sea have been able to flourish, from illegal fishing to human rights violations to maritime piracy. Lately, however, the rise of new methods of technological monitoring – from satellites to UAVs – has increased optimism that a better, technologically-aided method of ocean monitoring and governance may help to diminish the proliferation of these and other illegal activities. This paper considers the ways in which technological innovation has been proposed to help ocean monitoring and governance, and analyzes the extent to which the optimism over these new techniques is warranted.
This study was aimed at monitoring beach litter using an unmanned aerial vehicle (UAV) in the coastal city of Fuzhou, China. The data analysis shows that the optical images obtained by digital cameras on the UAV can help to identify and monitor beach litter using remote sensing and GIS technologies. The threshold method can effectively segment the UAV image in the beach area. It is useful for quickly monitoring the distribution of beach litter in the area of interest, and hence it can help to provide effective technical support for the investigation and assessment of coastal beach litter.