This paper presents a key technique that scientists from REEF and our Grouper Moon collaborators have used to monitor fish on the Little Cayman spawning aggregation that does not require the capture and handling of fish. We show that length-distribution data can be collected by divers using a video-based system with parallel lasers calibrated to a specific distance apart, and subsequently use those data to monitor changes in the size distribution over time.
Climate change is expected to cause a poleward shift of many temperate species, however, a mechanistic understanding of how temperature and species' life histories interact to produce observed adult range is often lacking. The authors evaluated the hypothesis that juvenile thermal tolerance determines northern range in gray snapper (Lutjanus griseus), a species commonly caught as juveniles along the US Atlantic coast well north of their adult distribution, using a combined laboratory, field and modeling approach. To evaluate the relationship between juvenile thermal tolerance criteria and adult distributions, the authors used the REEF database to quantify adult distribution. There was a strong correspondence between observations of adult gray snapper from the database of recreational divers vs. latitude with that of the predicted survival of juveniles vs. latitude from their modeling analysis. The agreement between the laboratory-derived thermal tolerance metrics, the spatial distribution of winter temperature, and the distribution of adult gray snapper support the hypothesis that the adult range of gray snapper is largely limited by the overwinter survival of juveniles.
This paper explores detectability rates of lionfish using underwater visual census methods such as belt transects and stationary visual census. Knowing the error in these methods specficially for lionfish is necessary to help study this invasive species in the western Atlantic. The research was conducted at the Cape Eleuthera Institute, where much of REEF's work on lionfish is conducted.The authors found that the two census methods detect fewer than 30% of lionfish present in an area and, in more than 50% of the cases, fail to detect any lionfish when one or more indivudals are actually present. Two factors affected the ability to detect lionfish: lionfish body size and habitat complexity.
This paper features research findings from powerful genetic techniques and the REEF survey data that reveal two new species of hamlet in the Caribbean. As REEF Caribbean surveyors know, hamlets are a group of colorful small sea basses that can sometimes cause ID confusion because of their myriad of colors and patterns. The varied color patterns in these small predators are thought to be a result of mimicry of other colorful herbivore species. There has been ongoing debate in the scientific world about which are actual species and which are simply just color variants or morphotypes. The research featured in the paper revealed significant genetic differences among what seemed to simply be variations of the well-known Barred Hamlet. The two new species are the Florida Barred Hamlet, Hypoplectrus floridae, and the Contoy Hamlet, H. ecosur. The typical Barred Hamlet (H. puella) that is found throughout the Caribbean will be updated to be called the Caribbean Barred Hamlet. Florida Barred Hamlet have been found in the eastern Gulf of Mexico and South Florida, and it overlaps in range with the Barred Hamlet in those area. At the time of publication, the Contoy Hamlet had only been documented on Isla Contoy near the northern tip of the Yucatan peninsula and possibly Isla Mujeres. Florida Barred Hamlet are distinguished by a pair of symmetrical dark spots at the base of the caudal fin along with a break in the mid-body narrow bar. The Contoy Hamlet is distinguished by the same paid of dark spots at the base of the tail as well as a series of additional dark spots along the upper caudal peduncle and below the dorsal fin.
There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems. Lead author, Stephanie Green, from Simon Fraser University (SFU), along with REEF Director of Special Projects, Lad Akins and other co-authors Aleks Maljković (SFU), and Isabelle Côté (SFU), documented a dramatic 65% decline in 42 species of reef fish eaten by lionfish over a two year period. The study, conducted off New Providence Island in the Bahamas, used data collected during REEF's volunteer lionfish projects to track the explosion of the lionfish population over time, and revealed that lionfish biomass increased from 23% to nearly 40% of the predator biomass on the study sites between 2008 and 2010. This study represents the first documented direct impact of lionfish predation on native reef fishes and highlights the importance of control programs to minimize impacts.
This seminal publication was created by REEF and our collaborators at NOAA, ICRI, the United Nations Environment Programme, Caribbean Environment Programme, SPAW-RAC, and the over 40 participants of the 2010 Caribbean Regional Lionfish Workshop. The guide provides best practices for lionfish control and management, including control strategies, outreach and education, research, monitoring, legal considerations, and ideas for securing resources and partnerships. By following these best practices, resource managers can reduce the local impacts of invasive lionfish in marine protected areas and other places of ecological and economic importance. Available online as a PDF through the link below. Also available as an ebook. Spanish edition also available (email reefhq@REEF.org for more information).
Members of REEF's Grouper Moon Project team, including researchers from Oregon State University, have been conducting annual monitoring of the size and color phase of individual Nassau grouper found at the spawning aggregation on Little Cayman in the Cayman Islands. During non-spawning periods Nassau grouper display a reddish-brown-and-white barred coloration. However, while aggregating they exhibit three additional color phases: “bicolor”, “dark”, and “white belly”. Each year, Grouper Moon Project researchers and volunteers use a video camera with lasers mounted on the camera housing. The divers focus the laser caliper equipped video camera on individual fish at the aggregation, capturing several seconds of footage for each fish. We later analyze the video to determine the length of the fish and record the color phase. This paper summarizes five years of video data. Our observations show that the relative proportion of fish in the bicolor color phase increases significantly on the day leading up to the primary night of spawning. The increase in the proportion of the bicolor color phase from 0.05 early in the aggregation to 0.40 on the day of spawning suggests that this color phase conveys that a fish is behaviorally and physiologically prepared to spawn. Additionally, 82.7% of fish exhibiting dark or white belly coloration early in the aggregation period suggests that these color phases are not only shown by female fish as was previously assumed in the scientific literature. This is just one aspect of the important marine conservation research being conducted as part of the Grouper Moon Project. To find out more, visit the Grouper Moon Project webpage.
Over the past decade, Indo-Pacific lionfishes have invaded and spread throughout much of the tropical and subtropical northwestern Atlantic Ocean and Caribbean Sea. These species are generalist predators of fishes and invertebrates with the potential to disrupt the ecology of the invaded range. Lionfishes have been present in low numbers along the east coast of Florida since the 1980s, but were not reported in the Florida Keys until 2009. This paper uses data from the 20,000+ REEF surveys conducted in Florida since the early 1990s, along with other long-term data sources, to document the appearance and rapid spread of lionfishes in the Florida Keys. The results are the first to quantify the invasion of lionfishes in a new area using multiple independent, ongoing monitoring data sets, two of which have explicit estimates of sampling effort. Between 2009 and 2011, lionfish frequency of occurrence, abundance, and biomass increased rapidly, increasing three- to six-fold between 2010 and 2011 alone. In addition, individuals were detected on a variety of reef and non-reef habitats throughout the Florida Keys. Because lionfish occurrence, abundance, and impacts are expected to continue to increase throughout the region, monitoring programs like REEF's Volunteer Survey Project will be essential to document ecosystem changes that may result from this invasion.
The authors of this study observed grouper and and their associated reef fish assemblage using scuba and underwater stationary videography during a 7-mo period. Fifty-seven sites around Cape Fear, NC, were visited with stationary video and diver point counts of groupers were taken at each site. Data collected as part of the REEF Volunteer Fish Survey Project, as well as several other datasets, were used to compare with the study results. Similar to other comparative studies previously published, the authors found that different survey methodologies have varying success at detecting even common species.
REEF Advanced Assessment Team Member, Dave Grenda, recently co-authored a paper documenting behavioral observations of young Great Barracuda occurring on live bottom sub-tropical reefs primarily at Gray's Reef National Marine Sanctuary off the coast of Georgia. For the past three years Dave assisted University of Connecticut researcher, Dr. Peter Auster, in studying behavioral interactions of piscivores and their prey. During REEF surveys on these cruises, Dave and the other researchers documented young-of-year (YOY) Great Barracuda (those individuals that had very recently settled to the reef, and were between 2-3 inches in length) hunting YOY Tomtate and Silverside that were taking refuge under ledges. Groups of YOY Barracuda would attack, capture, and consume the prey. Prey that escaped the Barracuda retreated to reef edges and were often consumed by bottom-dwelling adult piscivores such as Black Sea Bass, Bank Sea Bass, and Scamp Grouper. These findings indicate that given the strong functional role the young Barracuda have on driving species interactions, greater attention should be given to the roles played by the wider diversity of YOY piscivores recruiting to reef communities.