Bejarano-Rodríguez, Ivonne

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    Relationships between reef fish communities, water and habitat quality on coral reefs
    (2006) Bejarano-Rodríguez, Ivonne; Appeldoorn, Richard S.; College of Arts and Sciences - Sciences; Hensley, Dannie A.; Yoshioka, Paul; Aponte, Nilda E.; Department of Marine Sciences; Ojeda, Edgardo
    Rapid urban and industrial development is causing water quality deterioration in coastal marine environments. Sediment and nutrient inputs increase water turbidity, limiting light availability and reducing the photosynthetic capacity of the reef. Turbidity can also lead to organism stress, suffocation or death. Consequently, many coral reefs are declining, resulting in a loss of biodiversity and economic yield. This study investigates the relationship between water turbidity, measured as vertical attenuation of PAR (Kd), and coral and fish communities. At 35 reef sites in southwest Puerto Rico spanning a range of water turbidity, Kd was measured, and fish and coral communities were characterized. Coral and fish parameters varied with turbidity, showing higher diversities and abundances in clearer waters. Reef fishes responded to a combination of habitat characteristics. Turbidity, reef rugosity and percentage of live coral were significant variables affecting the reef fish community, and therefore are useful predictors of reef community health.
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    Deep reef fishes off La Parguera insular slope, Puerto Rico, and their connectivity with shallow reefs
    (2013) Bejarano-Rodríguez, Ivonne; Appeldoorn, Richard S.; College of Arts and Sciences - Sciences; García-Sais, Jorge R.; Yoshioka, Paul; Sabat, Alberto; Kubaryk, John; Department of Marine Sciences; Grove, Kurt
    This dissertation characterizes the fish community associated with Mesophotic Coral Ecosystems (MCEs) of the La Parguera shelf-slope between 2007 and 2011 using rebreather trimix technical diving. Fishes were identified, counted and lengths estimated within belt transects (30 m2) and roving surveys at 30, 40, 50, 60 and 70 m depth. Vertical transects from 70 to 30 m depth helped determine depth distribution ranges. The MCE fish assemblage (40-70 m) was distinct from shallow areas (30 m), with taxonomic composition, abundance and the proportion of trophic guilds varying with increasing depth. Most fishes at MCE were primarily shallow species, but others were restricted to mesophotic depths. An additional 15 species were added to those previously classified as indicator species of mesophotic areas in Puerto Rico. Fish abundance and species richness within MCEs were high. A total of 103 species were identified. The dominant trophic guild within MCEs were the zooplanktivores, while herbivores dominated shallow reefs. Both herbivores and zooplanktivores varied markedly and inversely to depth. The largest changes within the mesophotic fish community along the depth gradient occurred at 60 m, similar to that reported for algae and corals, and seem to represent both a response to reduced light and variations in herbivory. This study represents the first quantitative in situ descriptions of fishes inhabiting MCEs at depths of 50–70 m in Puerto Rico and highlights the role of MCEs as valuable habitats for reef fishes. This study examined the connectivity between shallow and mesophotic depths as expressed by the distribution and movement of fishes, and explicitly tested if MCEs represent an additional habitat and potential refugia for shallow reef fishes, particularly for commercially targeted species. MCEs along the La Parguera shelf-edge are subject to relatively more stable environmental conditions and a much lower impact from fisheries than shallow reefs. Seventy-eight shallow species were present at MCEs, and six different potential patterns of connectivity between shallow and mesophotic habitats are reported here based on the variability in the composition, relative abundance and presence of juveniles. Significant connectivity occured in both directions and for some ontogenetic migrators presence within MCEs appeared to be dependent on shallow production. Thirty-seven species were of fisheries value, and most of those are also species of conservation concern as they were once common in shallow reefs but have markedly declined in abundance in the area in the last 30 years likely due to high historical fishing pressure (e.g., sharks, large groupers, snappers, parrotfish). Because connectivity allows the dispersal of both larvae and adults, we believe that the present day spawning stock of some species (e.g., black grouper, dog snapper) may be made up for the most part of remnant populations within deep MCEs. This has important economic and ecological implications, and therefore fish populations in MCEs need to be protected when managing heavily exploited fishes, and this will enhance reef system resilience and stability. Lastly, this study investigated the effect of topographic complexity on the reef fish assemblages with MCEs by assessing the association between different complexity measurements (e.g., habitat relief, chain rugosity, slope) and fish community structure. Statistical tests and nonmetric multidimensional scaling (NMS) identified topographic complexity as an important parameter affecting ecological processes on MCEs, as reflected by changes in the composition and abundance of reef fishes. Higher overall fish abundance and species richness were found at high complexity sites, as well as higher abundance of zooplanktivores, piscivores, and large bodied vulnerable and commercially important fishes. Gross relief characterization was the complexity variable that better related with changes in fish assemblages at both species-specific and community levels. Because fishes in complex MCE sites are more diverse and abundant, and include several large bodied vulnerable commercial fishes that have virtually disappeared from shallow reefs in the area, these sites should be considered as prime areas targeted by fisheries management and coral reef conservation programs. This dissertation increases our understanding of reef fish ecology, including commercial species, and highlights the role of MCEs as valuable habitats for reef fishes. The results emphasize the importance of incorporating the composition and distribution of the MCE fish community when planning for the spatial management of coral reef resources.