Differences in diet and foraging behaviour of commercially important rabbitfish species on coral reefs in the Indian Ocean

Ebrahim, Ameer; Martin, Tyson S. H.; Mumby, Peter J.; Olds, Andrew D.; Tibbetts, Ian R.

doi:10.1007/s00338-020-01918-6

Cited by 16 publications

(15 citation statements)

References 70 publications

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“…Epiphytic material is an important food source for many small invertebrate grazers in tropical seagrass meadows (Belicka et al, 2012), which can be a primary food source for juvenile grunts and snappers (de la Moriniere et al, 2003). Likewise, epiphytes constitute an important food source for generalist herbivores like rabbitfish (Ebrahim et al, 2020b).…”

Section: Discussionmentioning

confidence: 99%

Seagrass Structural Traits Drive Fish Assemblages in Small-Scale Fisheries

et al. 2021

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Seagrasses – a group of foundation species in coastal ecosystems – provide key habitat for diverse and abundant faunal assemblages and support numerous ecosystem functions and services. However, whether the habitat role of seagrasses is influenced by seagrass diversity, by dominant species or both, remains unclear. To that end, we sought to investigate the specific seagrass characteristics (e.g., species diversity, seagrass traits) that influence tropical fish assemblages, and place this in the context of small-scale fishery use. We surveyed seagrass variables at 55 plots, nested within 12 sites around Zanzibar (Tanzania) in the Western Indian Ocean, and used Baited Remote Underwater Video (BRUV) systems to assess fish assemblages across plots. Using linear mixed models, we reveal that seagrass structural complexity and depth were the best predictors of fish abundance, with higher abundance occurring in deeper meadows or meadows with high canopy, leaf length and number of leaves per shoot. Moreover, an interaction between seagrass cover and land-use was the best predictor of fish species richness, where sites closer to human impacts were less affected by cover than sites with lower human impact. Overall, models with seagrass species richness or functional diversity as predictors poorly explained fish assemblages. Fish taxa that were important for small-scale fishery sectors (e.g., emperors, snappers, rabbitfish, and parrotfish) were primarily driven by seagrass structural complexity. Our results provide a unique analysis of the relationship between seagrass habitat and its associated fish assemblages in that we show that seagrass species diversity had little effect on seagrass fish assemblages, which instead appear driven by specific seagrass traits and seagrass cover. If conserving high value species that support adjacent fisheries is the priority for protecting seagrass meadows, then seagrass areas should be chosen with high cover and structural complexity that are in deeper waters. Any conservation measures also need to balance the needs of fishers that use the resources supported by seagrasses.

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Section: Discussionmentioning

confidence: 99%

Seagrass Structural Traits Drive Fish Assemblages in Small-Scale Fisheries

et al. 2021

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“…The spatial overlap of temperate and range‐expanding tropical herbivores will determine changes in functional diversity and redundancy of herbivory; however, since many species have functional plasticity (i.e. they can graze or browse on different macrophytes; Bennett et al., 2015; Ebrahim, Martin, Mumby, Olds, & Tibbetts, 2020; Zarco‐Perello et al., 2019), the execution of each function also depends on the spatial overlap between consumers and food resources. The concept of spatial overlap within ecological communities has been applied to estimate trophic interactions between species of predators and their prey (e.g.…”

Section: Introductionmentioning

confidence: 99%

Range‐extending tropical herbivores increase diversity, intensity and extent of herbivory functions in temperate marine ecosystems

et al. 2020

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Climate change is modifying species distributions around the world, forcing some species poleward, where they can alter trophic interactions. Many tropical herbivorous fishes have successfully expanded their ranges into temperate ecosystems, and while it is clear they drive increases in herbivory rates in specific localities, little is known about how they might affect the diversity of herbivory functions across large spatial scales, considering their interaction with assemblages of native herbivores in temperate habitats. We assessed the spatial overlap and habitat associations of native temperate and range‐expanding tropical herbivorous fishes in six subregions of south‐western Australia to determine how incursions of tropical species may have affected the diversity, redundancy (index of uniqueness) and the ‘spatial extent’ (addition of functions in new areas) and ‘intensity’ (increasing density of functional groups) of specific herbivory functions in recipient ecosystems. Tropical herbivores had high abundances in temperate ecosystems, forming schools from 40 (parrotfish) to 200 (rabbitfish) individuals strongly associated with seagrass meadows and reefs with high cover of turf algae. Overlap with temperate herbivores was highest in the northern subregions, forming unique assemblages, with no apparent species displacements. The addition of tropical species increased functional diversity and uniqueness (the complement of redundancy), introducing novel herbivory functions to many locations. Seagrass browsing increased in spatial extent (27%) and intensity (15×), while seaweed browsing and grazing increased in intensity by up to 2.5× in regions with high abundances of tropical herbivores. Our results suggest that the diversity, intensity and spatial extent of different herbivory functions can change as tropical species with different habitat affinities, behaviours and diets shift their distributions poleward. Changes in functional redundancy are likely to be heterogeneous in space and might not increase initially because the diversity of herbivory functions is relatively low in some temperate marine ecosystems. However, there is the potential for greater redundancy as further tropical species arrive, their abundances increase and the spatial and functional overlap of communities rises. A free Plain Language Summary can be found within the Supporting Information of this article.

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“…rivulatus as macroalgal browsers based on dietary information (Ebrahim et al, 2020) and the detritivores S. stellatus and C. striatus as grazers (Afeworki et al, 2013;Marshell and Mumby, 2015) (Table S3).…”

Section: Survey Methodsmentioning

confidence: 99%

Herbivorous fish of Sinai marine protected areas (Gulf of Aqaba): Structure baseline for potential thermal stress impact management

El-Haddad¹,

Mohamed

Temraz

et al. 2021

Preprint

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Herbivorous reef fishes are critically important for maintaining the health and resilience of coral reefs. In the Egyptian Gulf of Aqaba (GoA), many of these herbivores are important fishery targets and little is known about their population size structure and biomass patterns. Here, we conduct a large-scale (~250 km of coastline) assessment of the status of herbivorous fish populations along a fishing pressure gradient at 30 sites and eight regions in the GoA. These regions are subjected to three levels of fishing and protection, ranging from almost no fishing (No take, NT), and moderately fished (via Gear restriction, GR) to heavily fished (Open access, OA). We found that the NT fishery reserve was the most effective to maintain herbivorous fish size, biomass, and richness across all functional groups, though numerical density was not. Total herbivore biomass was 4.3 and 2.8 times higher on NT reefs and GR reefs, respectively than on OA reefs. Among GoA regions, only Ras Mohammed and Sharm El-Sheikh (unfished), and Nabq (fished) met the global mean herbivore biomass target of ~30 kg/500 m2. Our work also highlights three important results regarding the impacts of fishing and fisheries management on herbivorous fish populations: (i) size structure was heavily skewed toward smaller individuals, with fishes less than (20 cm) accounting for 81.1% of the population in heavily fished OA reefs vs. 52.8% at unfished NT reefs, (ii) biomass of larger herbivore individuals (>35 cm) accounting for less than 1% of the total biomass in OA reefs vs. 37% at NT reefs, and (iii) large-bodied target species, Cetoscarus bicolor, Naso unicorn, and Kyphosus spp., accounting for 15.9% of the total biomass at NT reefs on average, while they were virtually absent from OA reefs. Collectively, these findings suggest that many principal fisheries species in the central northern regions of the GoA have been overexploited, which in turn can lead to reef degradation. Therefore, there is an urgent need to develop a participatory management approach and enforce restrictions on destructive fishing gear in order to promote recovery of herbivore biomass.

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Differences in diet and foraging behaviour of commercially important rabbitfish species on coral reefs in the Indian Ocean

Cited by 16 publications

References 70 publications

Seagrass Structural Traits Drive Fish Assemblages in Small-Scale Fisheries

Seagrass Structural Traits Drive Fish Assemblages in Small-Scale Fisheries

Range‐extending tropical herbivores increase diversity, intensity and extent of herbivory functions in temperate marine ecosystems

Herbivorous fish of Sinai marine protected areas (Gulf of Aqaba): Structure baseline for potential thermal stress impact management

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