Studies of lionfish feeding ecology seek to document the ecological impact of this invasive predatory species and determine which native prey species are at greatest risk. There are 2 common approaches to feeding ecology through gut content analysis: morphological identification to the lowest possible taxonomic rank and/or DNA barcoding of individual prey components in the stomach. The major disadvantage of both techniques is their inability to use advanced digested material. This study introduces next-generation sequencing to lionfish feeding ecology, employing DNA metabarcoding to analyze all components of the gut contents, including the previously unidentifiable portion. Sixty-three lionfish were caught from the inshore and offshore reefs of La Parguera, Puerto Rico. Stomach contents were separated into 2 sample componentsa liquid (i.e. digested) and undigested tissue. A 313 bp region of the cytochrome oxidase subunit I (COI) gene was amplified from extracted DNA using specific primers for Caribbean reef fish. Samples were sequenced with an Illumina MiSeq platform, and the resulting 950+ sequences were compared against GenBank and the Barcode of Life Database to identify specimens at the lowest taxonomic level. Thirty-nine fish species from 16 families were identified (35 each in the digested and tissue fractions), including members of Pomacentridae, Acanthuridae, Gobiidae, Apogonidae, and Scaridae. Using the digested liquiform material proved efficient in detecting prey species, especially those that would have been missed with traditional methods.

The live marine baitworm trade harvests, packages, and ships polychaete worms and packing algae (wormweed) from Maine, USA to consumers globally, inadvertently transferring numerous invertebrates that naturally occur in the algal habitat. Here, we use a focal taxa, the globally invasive European green crab Carcinus maenas, to examine costs associated with the successful introductions via this vector and suggest an alternative packaging, already in use in Europe. We show that restricting the use of wormweed at the source could solve the problem of transferring hitchhikers without a change in product cost. However, to the extent that baitworms in wormweed are what US consumers are accustomed to receiving, alternative packing might restrict demand for baitworms, lower producer prices, and reduce quantities traded. Avoiding such economic costs and receiving the benefits of reduced likelihood of unwanted invasion at low or no cost to producers should be of interest to policymakers and practitioners tasked with protecting ecosystems.

Queen conch Lobatus gigas is one the most important fisheries species in the Caribbean. Currently, queen conch harvest is prohibited in the Exclusive Economic Zone (EEZ) in Puerto Rico. Since 1996, abundance estimates in Puerto Rico have been conducted by scuba divers at intervals of five years. Yet, diver surveys are limited by depth and time. In contrast, underwater video or camera surveys are not constrained by these factors and also provide a permanent photo record of observations. We conducted a survey of queen conch density on the western shelf of Puerto Rico in 2016 using two different methods: divers and a camera sled. Divers surveyed eight transects of 2-3 km using diver propulsion vehicles and standardized, historical methods. The camera sled was fitted with a digital camera, synchronized strobe lights, and paired lasers, and was towed along the dive transects several days later. Conch densities (#conch/ha) estimated with the camera sled were significantly higher than those estimated by diver survey methods while mean length was smaller. Both results were driven by the higher selectivity of the sled method for smaller conch. These results may lead to further applications or development of sled survey techniques, and improved data collection and analysis that can be used for management of queen conch in the Caribbean.

Background Over the past decade, environmental DNA (eDNA) has become a resourceful tool in conservation and biomonitoring. Environmental DNA has been applied in a variety of environments, but the application to studies of marine fish, particularly at tropical latitudes, are limited. Since many commercially important Caribbean fishes are overexploited, these species are optimal candidates to explore the use of this method as a biomonitoring tool. Specifically, for many of these species, the formation of fish spawning aggregations (FSAs) marks a critical life history event where fishes will gather in large numbers for reproduction. These FSAs are ephemeral in nature, lasting only a few days, but are predictable in time and space which makes them susceptible to overfishing. Methods In this study, we test the feasibility of using an eDNA sampling approach (water and sediment collection) to detect the presence of known FSAs off the west coast of Puerto Rico, with cytochrome c oxidase subunit 1 (CO1) and 12S rRNA (12S) primers designed to target specific species. A total of 290 eDNA samples were collected and, of those, 206 eDNA samples were processed. All eDNA samples varied in DNA concentration, both between replicates and collection methods. A total of 12 primer sets were developed and tested using traditional PCR and qPCR. Results Despite validation of primer accuracy and sample collection during known peak spawning times, the use of traditional PCR and qPCR with both molecular markers failed to produce species-specific amplification. Thus, a trial test was conducted using the CO1 primers in which target fish DNA was ‘spiked’ at various concentrations into the respective eDNA samples to determine the target species DNA concentration limit of detection. Upon successful amplification of the trial, results indicated that eDNA samples were below the detection threshold of our methods, suggesting that the number of fish present at the spawning aggregations was inadequate for single-species detection methods. In addition, elements such as the unavoidable presence of non-target DNA, oceanic environmental conditions, shedding rates of target fish, among other biotic and abiotic factors could have affected DNA persistence and degradation rates at the sites. Conclusion We provide recommendations for species-specific fish detection in lower latitudes, and suggestions for studies aiming to monitor or detect fish spawning aggregations using eDNA sampling.

The reaction of a manatee mating herd to the presence of two SCUBA divers in Puerto Rico is presented.