Artificial reef

Abstract: Sets of artificial reefs were replicated in 5 bays off Tortola in the British Virgin Islands to investigate the effects of habitat complexity on fish assemblages. Increasing percentage hard sub- strate and the number of small reef holes increased fish abundance on reefs. The observed number of species (Sobs) occurring on each reef increased with increasing rugosity, variety of growth forms, percentage hard substrate, and variety of refuge hole sizes. A rarefied or abundance-corrected spe- cies richness measure (Srare) was calculated to take the varying fish abundances into account. After this correction, rugosity was the only variable that significantly increased fish species-richness. Experimental reefs of different height (20 and 60 cm) did not have significantly different fish abun- dance or species richness. The presence of long-spined sea urchins Diadema antillarum increased Sobs and total fish abundance on artificial rock-reefs and in seagrass beds, but the effect was most pronounced in seagrass beds where shelter was a strongly limiting factor. These results indicate that complex habitats or animals such as D. antillarum that provide shelter to fish are essential for main- taining fish biodiversity at local scales. The most important aspects of complexity are rugosity, hard substrate and small refuge holes. Artificial reefs may be used to mitigate habitat damage in impacted areas, and if management objectives are to increase local fish abundance and species richness, the reefs should provide a stable substrate where this is unavailable, have a rugose surface with many small refuge holes, and have a variety of growth forms.

Abstract: Silva, R.; Mendoza, E., Marino-Tapia, I.; Martinez, M.L., and Escalante, E. 2016. An artificial reef improves coastal protection and provides a base for coral recovery. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 467-471. Coconut Creek (Florida), ISSN 0749-0208. In 2007, Hurricane Dean caused extensive damage along the coast of Riviera Maya, exceptionally large mass of wind-transported sand was deposited on the beach front and gardens of the former NH Hotel in Puerto Morelos. Due to the chaotic sea state and the debris carried by the storm, the sand was contaminated with various pollutants, including terrigenous materials and biogenic matter. As an emergency measure, this sand was used to create an artificial dune in the grounds of the hotel. Given the high probability of future storms of such magnitude, it was decided that some form ...

Abstract: Fifty standard concrete modules were deployed on a sand bottom to make 16 replicated artificial reefs of 1 to 8 modules·reef-I. Fish assemblages were monitored for species composition, abundance, and fish size, and compared to two natural control sites. We censused 127 species (107,168 fishes) from artificial reefs, 93 species (16,495 fishes) on natural control reefs, and 17 species (1,040 fishes) on sand bottom from July 1987 to March 1989. Artificial reefs supported a diverse, abundant, and dynamic assemblage of fishes that were a mixture of species found in surrounding sand. and natural reef habitats. Colonization (number of species, individuals, and biomass) was very rapid. Abundance varied seasonally with recruitment episodes tending to occur in the spring and summer followed by losses for the remainder of the year. Assemblages were quite variable on and between similar sized reefs. Fish and biomass densities were higher at artificial reefs than on sand and natural reefs. Resident fish biomass varied less than resident fish numbers, because individual growth compensated for mortality after recruitment episodes. Reef size significantly influenced total numbers of species, individuals, and biomass. Smaller reefs had greater fish density while larger reefs had higher biomass density from larger, but fewer, individuals. Multiple small reefs supported more individuals and more species than one large reef of equal material. Fishes recruited by larval settlement accounted for 36% of the total resident abundance but only 2% of total biomass. As reef size increased, older juvenile or adult colonists comprised a greater percentage of total biomass (94% to 99%). Assemblage importance percentages (based on abundance, biomass, and frequency) were divided between residents (64%), visitors (20%), and transients (16%). Economically important species comprised 61 % of the biomass and 55% of the individuals, among which settlers accounted for 94.3% of individuals but only 5.7% of their total biomass. The most highly valued species were visitors or residents that utilized the reefs after first settling elsewhere. These results showed that data on artificial reef assemblages based solely on the abundance of resident species are biased. Data on· visitors, transients, frequency-of-occurrence, and biomass are important in evaluating bias. Results provided a partial test and support for a model predicting the importance of attraction over production for artificial reefs located in areas with high reef availability.