Pedro Henrique Cipresso Pereira

Coral reef fish association with macroalgal beds on a tropical reef system in North-eastern Brazil

Macroalgal beds are recognised for their role as nursery and feeding grounds for several marine species. This study was conducted in the Tamandarereef complex within the limits of the Costa dos Corais Marine Protected Area (MPA), North-eastern Brazil. The macroalgal bed studied is subjected to several disturbances, especially from tourism. The reef fish were assessed with free dives during the day and night using visual censuses within transects (20 � 2m) and random swims. The percentage algal cover was estimated using quadrats (40cm 2 ). The behavioural traits of the fish also provided an understanding of their habitat use. In total, 68 fish species were recorded. The most abundant species were representatives of the families Labridae, Pomacentridae, Acanthuridae and Haemulidae. Sargassum polyceratium, Dictyopteris delicatula and Canistrocarpus cervicornis were the most abundant macroalgae. Because the most abundant fish trophic guild included primarily mobile invertebrate feeders (41.8%) and carnivores (28.4%), it is suggested that the high-canopy macroalgae harbour epiphytic invertebrates, which these fish use for food. Thereby, the study area would act as important nursery and feeding grounds. Tourism activity (e.g. laying chairs, trampling and anchoring) may disrupt fish behaviour and life-history traits and resultindamage thatwould require mitigationthrough environmental awareness and law enforcement in the most affected areas. Additional keywords: associated macrofauna, macroalgal beds, nursery areas, shelter.

Coral reef fish association and behaviour on the fire coral Millepora spp. in north-east Brazil

The branching structure of the coral colonies from the genus Millepora provides substrate, shelter, and food resources for several reef organisms, such as fish and invertebrates. The present work analysed the association and behaviour of reef fish on the fire coral Millepora alcicornis and M. brasiliensis from September 2010 to February 2011, on the coastal reefs of Tamandare, north-east Brazil. A total of 473 reef fish individuals of 27 species were sighted associated with the coral colonies, mainly composed of juveniles (65%). The most frequently observed behaviours were sheltered/stationary and swimming close to the coral; however, individuals were also observed foraging and breeding among Millepora spp. branching colonies. The agonistic behaviour performed by Stegastes fuscus individuals was highlighted in the present study, especially against Chaetodon striatus, Diodon holacanthus and Ophioblennius trinitatis individuals. Millepora spp. hydrocorals are ecologically important for juvenile and adult reef fish belonging to several trophic guilds. The complex structure of the coral colonies provides a wide variety of ecological functions on coral reefs (e.g. shelter, reproduction area, food and even territory). Nevertheless, the abundance of branching fire coral in Brazilian reefs have been declining over the past years; therefore, efforts must be made to protect this key habitat.

Competitive mechanisms change with ontogeny in coral-dwelling gobies

Recent theory suggests that a mix of lottery and niche processes can facilitate coexistence between competing species, but this has not yet been empirically tested. Previous research has suggested that a competitive lottery for space promotes coexistence between two ecologically similar species, Gobiodon histrio and Gobiodon erythrospilus. However, not all the assumptions of lottery competition have been tested, and patterns of habitat use by adults suggest niche partitioning. Here, we investigated the hypothesis that the mechanism of competition changes with ontogeny, with a lottery for space operating at settlement and niche partitioning occurring in adults. Patterns of resource use in the field were compared for juveniles and adults of the two species. Pelagic larval duration (PLD) and size-at-settlement was also estimated to determine if size differences at settlement could affect the outcome of competitive interactions among juveniles. Habitat preference and size-based competitive ability were then tested for juveniles and adults in laboratory experiments. Finally, a transplant experiment was performed to test the fitness-associated consequences of niche partitioning among adults and its implications for coexistence of the two species. G. histrio had a similar PLD (20.7 ± 2.0 days) to G. erythrospilus (18.5 ± 1.9 days), and there was no difference in size-at-settlement between the species. Juveniles of the two species had similar patterns of habitat use and similar competitive abilities, supporting the lottery mechanism at settlement. However, adults differ in their habitat use, supporting the prediction that resource partitioning increases with ontogeny. In laboratory experiments, adults of each species preferred colonies of Acropora nasuta. However, G. histrio was a superior competitor and prevented G. erythrospilus from using A. nasuta in > 70% of the trials. In the field transplant experiment, G. erythrospilus (inferior competitor) suffered less of a fitness loss when occupying the non-preferred coral (A. spathulata) compared with G. histrio, which could explain its ability to persist when displaced by the superior competitor. These results suggest that the competitive mechanism operating between the two Gobiodon species shifts from a lottery for space to niche partitioning through ontogeny, and that these two mechanisms of competitive coexistence are not mutually exclusive.

The influence of fire-coral colony size and agonistic behaviour of territorial damselfish on associated coral reef fish communities

Branching hydrocorals from the genus Millepora play an important ecological role in South Atlantic reefs, where branching scleractinian corals are absent. Previous studies have shown a high proportion of reef fish species using branching fire-coral colonies as shelter, breeding, and feeding sites. However, the effects of Millepora spp. colony size and how the agonistic behaviour of a competitive damselfish affect the associated reef fish community are still unknown. The present study examined how fire-coral colony volume and the presence of a highly territorial and aggressive damselfish (Brazilian endemic Stegastes fuscus) affects the reef fish community associated with the fire-coral Millepora alcicornis. M. alcicornis colonies were surveyed from September 2012 to April 2013 at Tamandaré Reefs off Northeast Brazil. Our results show that the abundance and richness of coral associated fish was positively correlated with M. alcicornis coral colony volume. Additionally, behaviour of S. fuscus, the most abundant reef fish species found associated with fire-coral colonies (almost 57% of the fish community), was also influenced by fire-coral colony volume. There was a clear trend of increased agonistic behaviour and feeding on coral polyps as colony volume increased. This trend was reversed for the non-occupational swimming category, which decreased as M. alcicornis colony volume increased. Behavioural ontogenetic changes were also detected for S. fuscus individuals. Juveniles mainly showed two distinct behaviours: sheltered on coral branches and feeding on coral polyps. In contrast, adults presented greater equitability among the behavioural categories, mostly non-occupational swimming around coral colonies and agonistic behaviour. Lastly, S. fuscus individuals actively defended fire-coral colonies from intruders. A large number of agonistic interactions occurred against potential food competitors, which were mainly roving herbivores, omnivores, and sessile invertebrate feeders. To our knowledge, the present study provides the first evidence that through habitat competition, the presence of S. fuscus may affect reef fish communities associated with M. alcicornis coral colonies. Our findings also indicate that S. fuscus uses M. alcicornis coral colonies as part of their territory for shelter and foraging. In conclusion, M. alcicornis fire-coral colonies are extremely important habitats for reef fishes and the size and presence of a territorial damselfish are relevant variables for associated reef fish community.

Reef fishes foraging facilitation behavior: increasing the access to a food resource

Fishes associated in schools acquire adaptive advantages by grouping together, e.g., access to a larger variety of food resources, foraging sites, and protection against potential predators. This work presents the first record of a feeding association between the bucktooth parrotfish, Sparisoma radians and the sailor’s grunt Haemulon parra, on Tamandaré reefs, Southwestern Atlantic. Through this association, S. radians gained access to otherwise unavailable food resources to be found inside territorial damselfish domain, thus characterizing an event of foraging facilitation.

Ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae

Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM) with similar values for juveniles (86.6%), initial phase (88.1%) and terminal phase (88.6%) individuals. The second preferred benthos for juveniles was sponge (11.6%) compared with initial (4.5%) and terminal life phases (1.3%). Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev’s electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean.

Comparative Allometric Growth of the Mimetic Ephippid Reef Fishes Chaetodipterus faber and Platax orbicularis.

Mimesis is a relatively widespread phenomenon among reef fish, but the ontogenetic processes relevant for mimetic associations in fish are still poorly understood. In the present study, the allometric growth of two allopatric leaf-mimetic species of ephippid fishes, Chaetodipterus faber from the Atlantic and Platax orbicularis from the Indo-Pacific, was analyzed using ten morphological variables. The development of fins was considered owing to the importance of these structures for mimetic behaviors during early life stages. Despite the anatomical and behavioral similarities in both juvenile and adult stages, C. faber and P. orbicularis showed distinct patterns of growth. The overall shape of C. faber transforms from a rounded-shape in mimetic juveniles to a lengthened profile in adults, while in P. orbicularis, juveniles present an oblong profile including dorsal and anal fins, with relative fin size diminishing while the overall profile grows rounder in adults. Although the two species are closely-related, the present results suggest that growth patterns in C. faber and P. orbicularis are different, and are probably independent events in ephippids that have resulted from similar selective processes.

Difference in the trophic structure of fish communities between artificial and natural habitats in a tropical estuary

The present study tested the hypothesis that artificial habitats (pier and bridge) harbour different fish trophic guilds compared with natural habitats (mangrove roots) and that the trophic structure of fish communities on estuarine artificial habitats resembles adjacent coral reefs. High-definition cameras were used to survey the fish community associated with the different structures over a 6-month period. Benthos was also analysed following the point intercept method on the different habitats. In the estuary, fish abundance was up to threefold higher and species richness twofold higher on artificial structures compared with the natural habitat. Mangrove roots were mainly inhabited by juvenile carnivores, whereas the pier and bridge were mostly inhabited by sessile invertebrate feeders and roving herbivores. A less diverse benthic community was found on mangrove roots, mostly composed of mud and algae. In contrast, benthos at the bridge and pier was more diverse and dominated by sponges, octocorals and oysters. In addition, fish trophic structure from an adjacent coral reef area showed more than 60% similarity with the fish community on the artificial structures surveyed. The results of the present study indicate that artificial hard structures support unique fish communities compared with natural estuarine mangrove habitats.

“Swallowing it all” – Extreme ingestion capability of juvenile reef fish

During a predation event a juvenile grouper, rock hind Epinephelus adscensionis, fed upon the redlip blenny Ophioblennius trinitatis. It is important to highlight that both individuals had pretty much the same size during the predation event (around 5 cm); however, the grouper ingested the whole prey.

Behavioral and ontogenetic colour changes of a poorly known lutjanid

Abstract Despite its high economic value to fisheries, little is known about the ecology of the recently described Lutjanus alexandrei. This is the first report on the array of colouration exhibited by this species in its natural habitats: coral reefs, algal beds and mangroves. Five colour patterns occur in L. alexandrei, and they are related to different life phases or behaviour. Variable colouration is shown on the head, body and fin edges. Colour patterns range from uniform to barred and blotched, from white to red and brown. This variable colouration is mostly related to camouflage on different backgrounds. Some of these patterns are also displayed during interspecific associations. Further investigations are necessary to expand our knowledge on the ecology of this recently described species.