"Fish Proportional to Mangrove," REEF Paper Rocks Science

REEF Volunteer Diver surrounded by a school of fish -at heart of Marine grassroot Conservation

A new paper of NOAA Fisheries scientists working with researchers of the University of Miami RSMAS and the REEF Volunteer Fish Survey Project challenged established scientific belief and revealed that regionally Mangrove areas have a direct proportional relationship to communities of reef fish. The paper was published in the scientific Journal PLoS ONE.

REEF reported on their November monthly newsletter on the study which is the first to take on the study of mangrove and fish reef communities to a regional perspective. The wider region of the Caribbean was the focus of the study.

Regressions in population densities were detected in eight of 12 fishes examined -regression was linked to mangrove forest impact and abundance. Other regression results were linked by the study to potential human impacts such as fishing and habitat degradation and latitudinal influences. Scientists concluded that the average reef fish densities of at least six of the 12 focal fishes which were studied were directly proportional to mangrove forest areas.

“Several studies conducted at the scale of islands, or small sections of continental coastlines, have suggested that mangrove habitats serve to enhance fish abundances on coral reefs, mainly by providing nursery grounds for several species known to have different habitats as juveniles and adults. However, evidence of such enhancement at a regional scale has not been reported, and recently, some researchers have questioned the mangrove-reef subsidy effect,” the paper assured.

REEF -the main international volunteer diving foundation making an significant impact in the scientific world with the help of over 50 thousand divers, snorkelers, students and collaborators highlighted the importance of using the data which they have acquired over the decades. NOAA Fisheries added that the Mangrove study was possible thanks to 20 years of data.

“This study is a great example of the power and impact that long-term, widespread citizen science programs such as the REEF Volunteer Fish Survey Project can have on addressing important ecological and management questions that would otherwise be near impossible to evaluate,” REEF applauded their volunteer surveyors.

NOAA Fisheries went technical and explained that the main questions asked when evaluating mangrove-reef connectivity at the Caribbean Regional Scale were two. First they asked are reef fish abundances limited by mangrove forest area? Then they asked are mean reef fish abundances proportional to mangrove forest area after taking human population density and latitude into account?

The team of scientists focused on 12 reef fishes to evaluate their “mangrove-dependency”. The results showed that a larger scale the forest mangrove size functions to increase the densities of surrounding reefs which are used by fishes. The study also detected an important relationship between mangroves, reefs, fish and seagrass beds, the entire environment can be considered a single cell. Reef fish use the wider environment in their diverse cycles of life. Mangroves and seabeds usually serve as nurseries and reef environments home for maturity and other stages of reef fish.

The Paper found at Journal PLoS ONE going by the title “Mangroves Enhance Reef Fish Abundance at the Caribbean Regional Scale” goes even more specific and opens the entire report including graphs and modelling to the public domain. Just like any diver with a will can find their way to a REEF Volunteer Program any person with an internet connection can find their way to the entire NOAA led paper. The importance of citizen-science in globalized times manifests itself spontaneously but it is actually the result of long years of work.

“Analyzed were data from an ongoing, long-term (20-year) citizen-scientist fish monitoring program; coastal human population censuses; and several wetland forest information sources,” the paper states.

The area studied spanned from Florida US to South Venezuela and included 25 countries/island nations. Mangroves, Reef Fish, Reef, Human Density and other elements were factored into the equations.

The 12 Mangrove-Dependent Reef Fish Species included in the study included three species belonging to the families Haemulidae, three for Lutjanidae and two for Scaridae, Gerreidae specie and Sphyraenidae

Yellowtail snapper abundance maxima tended to decline as human population density increased, the opposite pattern emerged for yellowfin mojarra. Latitude revealed itself as a determining factor for populations of Great Barracuda (Sphyraena barracuda) and the Striped Parrotfish (Scarus iseri).

Using the REEF database and applying other tools the study found a negative Caribbean-wide human population effect for several predatory fishes, including five considered in the present study: yellowtail snapper; mutton snapper, gray snapper, schoolmaster and Great Barracuda.

“Our results contrast with the conclusions drawn by Saenger..., who conducted a literature review of mangrove and seagrass linkages to fisheries production for the United Nations Food and Agriculture Organization FAO. After considering more than 200 published studies, including most of those considered here, Saenger...was unconvinced of a clear fish-mangrove linkage, either within or among regions, largely because previous study findings appeared mixed and their spatiotemporal scale was limited. However, our Caribbean regional results contradict (that of) the Saenger,” NOAA, the University of Miami, REEF and the thousands of volunteer international divers which are at the grassroot of the marine conservation program rocked the established scientific beliefs on the issue.

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