Papers by Carlos A Sanchez-Caballero
Fishes, 2024
The distribution of fish eggs and larvae (ichthyoplankton) reflects spawning and nursery areas as... more The distribution of fish eggs and larvae (ichthyoplankton) reflects spawning and nursery areas as well as dispersal routes. This study’s goal is to demonstrate how the identification of ichthyoplankton species and stages and their spatial distribution among natural reefs (NRs) and artificial reefs (ARs) may serve as decision-making tools in conservation and fishery management. Natural reefs exhibited an eight-times higher abundance of eggs, as well as the highest abundance of larvae in the yolk-sac and preflexion phases. In contrast, ARs had the highest abundance of larvae in the flexion and postflexion phases. Natural reefs may serve as breeding grounds for Scaridae, Labridae, and Mugilidae; whereas, ARs may serve as breeding sites for Lutjanidae, Synodontidae, Carangidae, Fistularidae, and Haemulidae. Our study revealed differences between ARs and NRs, which demonstrate the potential of artificial reefs to expand the supply and settlement options of reef fishes and consequently can lead to increased fish production with potential benefits to adjacent fishing areas through connectivity. Thus, ARs as no-take sites can be effective tools for both fishery management and biodiversity conservation. The findings highlight the potential use of ichthyoplankton tools and the importance of considering both types of reefs in marine conservation and management efforts.
Estuarine, Coastal and Shelf Science, 2023
The marine protected area (MPA) of the Espiritu Santo Archipelago (ESA; Gulf of California), is e... more The marine protected area (MPA) of the Espiritu Santo Archipelago (ESA; Gulf of California), is exposed to a high level of anthropogenic disturbances, consequently, the local authorities have deployed artificial reefs (shipwrecks) in the ESA area to increase fishing refuges, breeding sites, and tourist attractions. To explore the potential contribution of these artificial reefs as a conservation tool, we compared their benthic community structures (i.e. diversity and live cover categories) to those of the natural reefs. Our results indicate a higher abundance of mollusks on the artificial reefs compared to the natural reefs; a higher echinoderm abundance on the natural reefs; and a very similar species richness of hexacorals between the natural and artificial reefs, with 10 and 9 species recorded respectively. The natural reefs hosted a four-fold higher live cover of hexacorals than the artificial reefs, while the artificial reefs had a higher number of octocoral species, 8 versus 5 on the natural reefs. In addition, the artificial reefs had a 4.6 fold higher octocoral cover than the natural reefs. Overall findings indicate that the benthic community assemblages significantly differ between the natural and artificial reefs, which may be related to their location, structural composition, material, and morphology. These results suggest that shipwrecks have the potential to enhance local reef diversity by increasing the cover and abundance of certain benthic-associated species. Although the shipwrecks do not function as surrogate habitats for the adjacent natural rocky reefs, as no-take areas they provide suitable refuges for several target species (e.g. black coral and mollusks).
Overfishing is a key stressor in many coral reefs, affecting their function and ecosystem service... more Overfishing is a key stressor in many coral reefs, affecting their function and ecosystem services. In the Gulf of California, 50 years of artisanal and recreational fishing have removed most of the largest and most vulnerable fish species, the Espiritu Santo Archipelago (ESA) is a marine protected area (MPA) where artisanal and recreational fishing are allowed in most of the natural reefs, while the artificial reefs (wrecks) are fully protected. An important question under such circumstances is whether artificial reefs can serve as surrogate habitats for the natural reefs. To address this question, we characterized the fish community (species richness, abundance, differences in taxonomic structure) and analyzed the obtained data by multivariate ordination and similarity analysis. The highest species richness was found in the artificial reefs, with total of 83 species, of which 21 species were exclusive. Contrary to the species richness, the total fish abundance was 20% higher at the natural reefs. The fish assemblages of the artificial reefs differ significantly from those of the natural reefs. The natural reefs of the ESA are dominated by few fish species from families of lower trophic levels. In contrast, the studied shipwrecks provide refuge to commercially important fish species (such as Snappers, Triggerfish, Jacks, and Groupers) including threatened species. The different fish compositions on the natural and artificial reefs is likely to be the outcome of differential fishing pressure. The non-fished areas (wrecks) of the ESA may represent a good strategy for reef restoration, enhanced fishing grounds (via spillover) and fishing management. However, the fish community structure of the artificial reefs differs from natural rocky reefs of the ESA, and therefore, should not be considered as surrogate habitats for natural reefs. The results point out the need to reassess the management effectiveness of the natural reefs of the ESA.
The Chametla wetland is used by shorebirds as a stopover site during their autumn migration and i... more The Chametla wetland is used by shorebirds as a stopover site during their autumn migration and it is also an important breeding area for several species of waterbirds. The objective of this work was to compare the bird assemblages in Chametla wetland during three sampling periods: 1) 1991-1992; 2) 1997-1998 which was subjected to El Nino Southern Oscillation (ENSO) climate conditions and 3) 2005-2006. Bird communities were characterized in terms of species composition and diversity, using similarity analysis. Bird assemblage composition differed across years and seasons. Seasonal variations in composition and diversity were related to the presence/absence of phenological-characterized species (migratory vs. wintering species). The highest species richness was recorded under the ENSO period (1997-1998). We observed a sharp decrease in shorebird numbers, with evident stress at the assemblage level throughout the entire study period. There seems to be a transition of the bird assemblages from shorebird dominance to a dominance by long-legged wading birds and waterfowl species, which could be related to water level variation and changes in the quality/availability of food in the intertidal zone. The joint pressures of regional climate variation combined with local anthropogenic perturbations may lead to changes in bird assemblage in the Chametla wetland.
The main effects of El Niño and La Niña on fish are increases in mortality rates, abundance and r... more The main effects of El Niño and La Niña on fish are increases in mortality rates, abundance and recruitment variation, and expansion/restriction in the range of distribution and spawning areas. Potentially, the interactions with seasonal effects can further exacerbate or dampen fluctuations in these parameters. The objective of this work, therefore, was to characterize the possible differences in the reef fish community structure in two seasons of the year (warm/cold) and between years (2010/2012) following El Niño-La Niña events. There were no significant differences in mean species richness between years. Furthermore, although more than twice the number of individuals was observed in the year after La Niña (2012) compared to the year following El Niño (2010), there were no significant differences with respect to mean abundance per transect. The total number of species recorded was slightly higher in the cold season, with 68 species across both years. In contrast, the total abundance was higher in the warm season. However, differences between seasons were neither significant for mean species richness nor for mean abundance. Neither season nor year exhibited a significant effect on community composition. The cold season in the Gulf of California is characterized by intense winds which generate a greater mixed layer; this, in turn, increases productivity, with cascading effects on higher trophic levels. In contrast, the presence of nitrogen-fixing picocyanobacteria which increase the levels of primary production may be a factor leading to maintaining a similar fish abundance in the warm season. Fluctuations between seasons and years of study were observed for some individual species, which may be related to oceanic productivity and reproductive periods. The results obtained in this work indicate that seasonality and climatic phenomena such El Niño and La Niña do not have a marked effect on community attributes of rocky reef fish in the southern Gulf of California, which apparently form a seasonally stable community, despite some fluctuations in individual species.
• Each coastal habitat contained a distinct species composition. • In the rocky substrate was rec... more • Each coastal habitat contained a distinct species composition. • In the rocky substrate was recorded the 88% of the total abundance and the 79% of the total richness. • The mobile invertebrate feeders were the trophic group with the highest richness and abundance. • The fish assemblage from sandy bottoms could be affected by the presence of artificial structures. a b s t r a c t Strong relationships exist between reef fishes and their habitat, anthropogenic habitat alterations may lead variations in the associated fish. Knowledge of fish species distribution over coastal areas heavily impacted by tourism over the Mexican Central Pacific is scarce. This work aims to identify the reef fish species on different coastal habitats (sand, rock, mud) present in Puerto Marques Bay. The fish community was characterized in terms of species richness, abundance, feeding behavior and was further assessed using similarity analysis. The number of species and the relative abundance of fish species recorded varied significantly among the habitats (ANOSIM test: R = 0.676, P < 0.01, 999 permutations). In rocky areas, the highest value of richness, exclusive species and the number of organisms were recorded. In comparison with soft bottoms, the complexity of hard substrates plays a significant role in reducing prey abundances and providing nesting sites and different food resources such as invertebrates and macroalgae. Mugil cephalus was the only species recorded with muddy habitat affinity, where it feeds on detritus. Predatory species like Caranx caballus, Lutjanus jordani and Lutjanus peru, generally associated with complex rocky substrates were recorded exclusively in sandy areas near to the tourist marina. Although our data do not allow to conclude the anthropogenic outcomes in the reef fish community structure, they suggest that fish assemblage from sandy bottoms could be affected by the presence of artificial structures.
In reefs, fish distribution and community structure are strongly linked to habitat structure. The... more In reefs, fish distribution and community structure are strongly linked to habitat structure. The objective of this study was to develop a baseline of the attributes of a rocky reef fish community threatened by development and their possible relationship with habitat complexity in order to assess how predicted habitat modification would impact the fish community. In the study area, the construction of a tourist marina is planned as part of a residential area with a total size of 500 ha. The project includes the translocation of corals, infilling of reclamation areas by dredging, and floating docks, which is predicted to affect both benthic rugosity and the types of benthic cover. Using hierarchical clustering based on benthic substrate type and rugosity we defined three levels of habitat complexity (Low, Medium, High). The fish community at different levels of complexity was characterized in terms of species richness, abundance, diversity and dominance, and was classified into seven trophic groups. Transects with high habitat complexity featured the highest cover of dead coral with macroalgae (43.7% ± 2.3, mean ± SE) and live coral (21.0% ± 1.9). There were no significant differences in rugosity among the three levels of habitat complexity (ANOVA, F ¼ 0.145, df ¼ 2, p ¼ 0.87). A total of 19,799 individuals belonging to 76 species were recorded over an area of 12,000 m 2. The greatest mean density and species richness occurred at high habitat complexity, with 1229.7 (±202.7) individuals per 500 m 2 and 64 species, respectively. Community structure was significantly different in richness and abundance between high and low levels of complexity (p < 0.05). It is expected that the benthic habitat will be modified mainly by dredging associated with the construction of reclamation areas and the translocation of benthic organisms (mostly corals), affecting the habitat variables associated with different levels of habitat complexity in our survey. Reducing habitat complexity as a result of development is predicted to lead to a loss of species richness and ecological functions. A better understanding of the influence of habitat complexity on reef organisms can help to predict the potential impacts of habitat degradation and develop appropriate mitigation measures. Based on the results, a number of measures are suggested to detect and mitigate the expected negative impacts of construction and operation of the marina.
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Papers by Carlos A Sanchez-Caballero