Behaviour Of Reef Fishes Research Articles

Behavior of reef fishes during a submarine magnitude 5 earthquake.

Behavior of reef fishes during a submarine magnitude 5 earthquake.

How artificial potential field algorithms can help to simulate trade-offs in movement behaviour of reef fishes

IntroductionSpace use patterns in fish result from the interactions between individual movement behaviour and characteristics of the environment. Herbivorous parrotfishes, for instance, are constrained by the availability of resources and different predation risks. The resulting spatial distribution of the fish population can strongly influence community composition and ecosystem resilience.MethodsIn a novel approach, we combine individual-based modelling (IBM) with an artificial potential field algorithm to realistically represent fish movements and the decision-making process. Potential field algorithms, which are popular methods in mobile robot path planning, efficiently generate the best paths for an entity to navigate through vector fields of repellent and attracting forces. In our model the repellent and attracting forces are predation risk and food availability, both implemented as separate grid-based vector fields. The coupling of individual fish bioenergetics with a navigation capacity provides a mechanistic basis to analyse how the habitat structure influences population dynamics and space utilization.ResultsModel results indicate that movement patterns and the resulting spatial distributions strongly depend on habitat fragmentation with the bioenergetic capacity to spawn and reproduce being particularly susceptible processes at the individual level. The resulting spatial distributions of the population are more irregularly distributed among coral reef patches the more the coral reef habitat becomes fragmented and reduced.DiscussionThis heterogeneity can have strong implications for the delivered ecosystem functioning, e.g., by concentrating or diluting the grazing effort. Our results also highlight the importance of incorporating individual foraging-path patterns and the spatial exploitation of microhabitats into marine spatial planning by considering the effects of fragmentation. The integration of potential fields into IBMs represents a promising strategy to advance our understanding of complex decision-making in animals by implementing a more realistic and dynamic decision-making process, in which each fish weighs different rewards and risks of the environment. This information may help to identify core areas and essential habitat patches and assist in effective marine spatial management.

Agonistic behaviour in the long‐snout seahorse: A gentlemanly challenge

AbstractTerritorial defence is a relatively common behaviour in reef fish. Aggression typically occurs between individuals of the same sex, given that members of the opposite sex may represent potential breeding partners. Seahorses are cryptic reef fish with typical sedentary behaviour, especially during the male pregnancy. In this context, we investigated the agonistic behaviour of pregnant seahorses, Hippocampus reidi, towards other males, pregnant or not, relating the duration of their interactions to the size and robustness of the resident and intruder. Robustness was measured as the circumference of the brood pouch divided by total body length. The study was based on four alternative treatments, which were monitored in situ: (i) a pregnant male in its home range was exposed to a pregnant intruder male; (ii) a non‐pregnant male in its home range was exposed to a pregnant intruder male; (iii) a pregnant male in its own home range was exposed to a non‐pregnant intruder male, and (iv) a non‐pregnant male in its home range was exposed to a non‐pregnant intruder male. The control to test for the effect of seahorse translocation on later displacement behaviour consisted of male seahorses translocated to an area of 60 m from the capture site and quantification of their displacement range. Low‐level aggressive behaviour was recorded in the trials, although the pregnant males presented dominance behaviour, both within and outside their own home ranges or territories, to expel intruders, while non‐pregnant males avoided interaction. No correlation was found between robustness and either the displacement of the intruder or the duration of the interaction.

Reef‐wide evidence that the presence of sharks modifies behaviors of teleost mesopredators

AbstractThe idea that the presence of sharks impacts the behavior of mesopredatory reef fishes is controversial and lacks clear evidence at reef‐wide scales. We compared the abundance and behavior of these reef fishes in response to the presence of reef sharks using Baited Remote Underwater Video System (BRUVS) deployments in two adjacent reef systems where sharks have either been exclusively targeted by fishing or protected by a no‐take marine reserve. For a subset of videos, we also compared the behavior of mesopredatory reef fishes immediately before and after the appearance of sharks in the video. On reefs where sharks were more abundant, mesopredatory fishes spent less time swimming in midwater (i.e., away from shelter) and guarding bait compared to reefs where sharks have been selectively removed. The same responses occurred after the appearance of sharks in the video. Reactions to sharks varied both in strength and type among species of mesopredator and were mediated by the availability of shelter on the reef and, for one species, by the levels of activity of the reef sharks. In contrast, we did not find that the presence of sharks influenced the abundance of mesopredators at either reef system across hour‐long videos or immediately before and after a shark appeared in the video. Collectively, our findings show that the presence of sharks reduces the propensity of mesopredatory fish to engage in potentially risk‐prone behaviors over large spatial scales and that these interactions are mediated by the behavioral characteristics of both predators and prey, and the environment in which they co‐occur. Our results are consistent with the idea that sharks as predators or larger competitors initiate changes in the behavior of mesopredatory reef fishes likely to affect trophic structuring within coral reef ecosystems.

Land-based noise pollution impairs reef fish behavior: A case study with a Brazilian carnival

Anthropogenic sounds have spread across the biosphere, with threats from individual welfare to ecosystem health. Sounds are important to animals in both terrestrial and aquatic environments and detrimental effects have been shown across a wide range of taxa. Despite the ever-growing transformation of coastal lands by human activities, pollutant effects of sounds that propagate from land into coastal water (across realms) have been largely overlooked. We here show that the Brazilian carnival of Salvador, annually taking place along a coastal boulevard, elevated underwater sound pressure levels by more than 30 dB re 1 μPa2. We used remotely operated cameras to measure individual abundance and feeding activity of the Brazilian damsels (Stegastes fuscus) and we measured its flight-initiation distance to a model predator. Brazilian damsels did not abandon their reef territories, but their feeding activity and fleeing distance were significantly reduced under elevated noise levels, compared to the ambient control conditions at the same site and at a spatial control site. Apparently, carnival sounds emitted from land affected underwater behavior in our reef fish species. The behavioral effects may be critically important for individual fitness, and the detrimental impact of land-based noise pollution in coastal waters may also apply to other fish and invertebrate species. Humanity is claiming coastlines at a faster rate than any other habitat, and conservation concerns should extend to nearby coastal ecosystems and the possible impacts of underwater sounds emanating from land.

Effects of depth on reef fish flight initiation distance: implications of deeper reefs conservation

A reduced susceptibility for local and global impacts has been assigned for deeper reefs compared to historically degraded shallow reefs. Yet, few studies have attempted to analyze the influence of depth on reef fish escape behavior across distinct size classes. By using behavioral response as a measure for prey wariness, the present study analyzed flight initiation distance (FID) for three fishery target and one non-target reef fish species on shallow and deeper reefs in South Atlantic Ocean (Multiple use MPA Costa dos Corais, Pernambuco State). We hypothesized that fish on shallow reefs would have higher FID and detect the human approach sooner and flee at a large distance than individuals in deeper reefs, which would have a late detection, allowing a closer approach. During our field experiment, flight initiation distances average was higher at shallow reefs for three analyzed species, yet each species had specific responses according to individual size classes. For two fishery target species E. adscensionis and C. fulva, two intermediate size classes presented higher flight distances at shallow than deeper reefs. However, S. axillare a target parrotfish, demonstrated an unexpected trend with higher FID on deeper reefs for smaller size classes. Interestingly, the non-target species, have also shown differences on wariness across the two analyzed size classes, with higher FID on shallow than deeper reefs. Our results suggest that fish on shallow reefs would detect the human approach sooner and flee at a large distance than individuals in deeper reefs; however, fish response to human presence according to depth is size classes and species dependent. We emphasis the important of no-take zones and the establishment of new marine protected areas on both shallow and deeper reefs in Brazilian waters and elsewhere in order to maintain the integrity of reef fish behavior and consequently ecosystems functioning.

Vessel noise affects routine swimming and escape response of a coral reef fish.

An increasing number of studies have shown that anthropogenic noise can negatively affect aspects of the anti-predator behaviour of reef fishes, potentially affecting fitness and survival. However, it has been suggested that effects could differ among noise sources. The present study compared two common sources of anthropogenic noise and investigated its effects on behavioural traits critical for fish survival. In a tank-based experiment we examined the effects of noise from 4-stroke motorboats and ships (bulk carriers > 50,000 tonnes) on the routine swimming and escape response of a coral reef fish, the whitetail damselfish (Pomacentrus chrysurus). Both 4-stroke boat and ship noise playbacks affected the fast-start response and routine swimming of whitetail damselfish, however the magnitude of the effects differed. Fish exposed to ship noise moved shorter distances and responded more slowly (higher response latency) to the startle stimulus compared to individuals under the 4-stroke noise treatment. Our study suggests that 4-stroke and ship noise can affect activity and escape response of individuals to a simulated predation threat, potentially compromising their anti-predator behaviour.

Non-consumptive effects in fish predator–prey interactions on coral reefs

Predator–prey interactions are critical in ecological communities, but it is increasingly clear that a predator’s effect goes beyond eating prey. Fear of predators may also alter the behaviour, physiology, and morphology of prey as they try to reduce risk. Such ‘non-consumptive effects’ (NCEs) may have important demographic effects on prey populations. The study of NCEs has recently grown significantly across marine ecosystems, including coral reefs. Coral reefs support diverse predator assemblages, and consumptive effects substantially impact prey populations, suggesting NCEs are also likely to be important. Indeed, a growing number of aquarium and field studies have demonstrated that the behaviour of reef fishes is changed by predators, typically using predator models or a gradient of fishing pressure. Here, we review these studies to summarise what is currently known about NCEs in reef-fish assemblages, including effects on individuals and populations and variations in space and time caused by predator and prey traits and environmental factors, and the evidence for NCEs driving trophic cascades. Critically, throughout we also draw on a wider literature to highlight hypotheses and theories emerging in other ecosystems that can inform further work on reefs. While it is clear NCEs are significant among reef fishes and can alter reef functioning, evidence of demographic changes, mechanistic pathways (e.g. behavioural vs. stress induced), and work with multiple predators and prey is lacking. We suggest that establishing an initial framework of interactions among different predator and prey types is needed, allowing the integration of factors such as habitat complexity and internal prey state (e.g. hunger), and an increased understanding of how fishes move around seascapes of fear and how to integrate NCEs into ecosystem models. Such integration is critical for a fuller understanding of how fish assemblages function, interact with benthic organisms, and will be affected by environmental stressors.

The influence of thermal extremes on coral reef fish behaviour in the Arabian/Persian Gulf

Despite increasing environmental variability within marine ecosystems, little is known about how coral reef fish species will cope with future climate scenarios. The Arabian/Persian Gulf is an extreme environment, providing an opportunity to study fish behaviour on reefs with seasonal temperature ranges which include both values above the mortality threshold of Indo-Pacific reef fish, and values below the optimum temperature for growth. Summer temperatures in the Gulf are comparable to those predicted for the tropical ocean by 2090–2099. Using field observations in winter, spring and summer, and laboratory experiments, we examined the foraging activity, distance from refugia and resting time of Pomacentrus trichrourus (pale-tail damselfish). Observations of fish behaviour in natural conditions showed that individuals substantially reduced distance from refugia and feeding rate and increased resting time at sub-optimal environmental temperatures in winter (average SST = 21 °C) and summer (average SST = 34 °C), while showing high movement and feeding activity in spring (average SST = 27 °C). Diet was dominated by plankton in winter and spring, while fish used both plankton and benthic trophic resources in summer. These findings were corroborated under laboratory conditions: in a replicated aquarium experiment, time away from refugia and activity were significantly higher at 28 °C (i.e. spring temperature conditions) compared to 21 °C (i.e. winter temperature conditions). Our findings suggest that P. trichrourus may have adapted to the Arabian/Persian Gulf environment by downregulating costly activity during winter and summer and upregulating activity and increasing energy stores in spring. Such adaptive behavioural plasticity may be an important factor in the persistence of populations within increasing environmentally variable coral reef ecosystems.

Fear-induced behavioural modifications in damselfishes can be diver-triggered

Fear is a short-term response arisen from the way an animal perceives its environment when some threat makes it insecure. Thus, the risk perception of predation shapes the cost-benefit decisions associated with food and safety in animal communities. Even non-consumptive human-related activities such as ecotourism may influence species behavioural traits. Marine wildlife tourism might produce different impacts on organisms, stressing and modifying (directly or indirectly) species behaviour, physiology and habitat use. Understand the effects of human presence on site-attached fish’ behaviour is crucial to elucidate how dive-tourism could shape their limited-range seascape. Given the importance of the territorial damselfishes as reef farmers and ‘ecosystems engineers', here we investigated if the presence of SCUBA divers and snorkelers can disrupt the foraging and territorial defence of the Dusky damselfish, Stegastes fuscus. Experimental approaches (diver presence and absence) were applied in 30 territories of S. fuscus using underwater remote video cameras. Behavioural responses were analysed by considering the frequency of refuge, foraging and chase behaviours. Both recreational dive activities had an analogous role in frighten and disturb the Dusky damselfish activities. Considering the frequency of behaviours displayed in diver's absence vs presence, S. fuscus increased its refuge times from approximately 2% to 50% on SCUBA diver presence and from 9% to 43% in snorkeler presence. It is directly linked to the missed feeding opportunities, which reduced by half during both diver's presence. Damselfish's aggressiveness proportionally dropped (0.3%) during SCUBA diver presence but increased (2.4%) while snorkeler was present. However, the average frequency of chase behaviour reduced with both divers' approach. Interruptions in damselfish behaviour may modify the resource monopolization and productivity inside their territories, affecting its relationships with other species beyond the boundaries of their territoriality, and leading a possible change on its functional role in the reef community. Territorial reef fish behaviour and their relationship with divers' presence can provide a more holistic comprehension regarding the seascape of fear concept and could be useful as an indicator of human disturbances.

“Boo! Did we scare you?”: behavioral responses of reef-associated fish, prawn gobies (Amblyeleotris steinitzi and Amblyeleotris sungami) to anthropogenic diver disturbance

Coral reef communities are susceptible to anthropogenic disturbance by visitors, such as SCUBA divers. Divers can also have an effect on the behavior of reef fish, which can lead to changes in activities or habituation. This effect was examined by focusing on two species of prawn gobies, Amblyeleotris steinitzi and A. sungami, at sites in Eilat, Israel. Gobies at both undived and heavily dived sites were disturbed and the time taken for re-emergence after disappearing (latency period) was measured. The flight initiation distances (FID), the distance at which the fish fled from an approaching threat, was also measured. It was hypothesized that reactions to disturbances would be less for the gobies accustomed to diver disturbance. Results showed that in anthropogenically disturbed areas, gobies had shorter latency periods than in undisturbed areas. FID were also significantly shorter. One of the undived sites, a steep gravel slope that experiences natural disturbance in the form of rolling gravel, showed the same trend of a short average latency period. Gobies at anthropogenically disturbed sites adapted their behavior to diver disturbance.

Macroscopic observations of diel fish movements around a shallow water artificial reef using a mid-frequency horizontal-looking sonar.

The twilight feeding migration of fish around a shallow water artificial reef (a shipwreck) was observed by a horizontal-looking, mid-frequency sonar. The sonar operated at frequencies between 1.8 and 3.6 kHz and consisted of a co-located source and horizontal line array deployed at 4 km from the reef. The experiment was conducted in a well-mixed shallow water waveguide which is conducive to characterizing fish aggregations at these distances. Large aggregations of fish were repeatedly seen to emerge rapidly from the shipwreck at dusk, disperse into the surrounding area during the night, and quickly converge back to the shipwreck at dawn. This is a rare, macroscopic observation of an ecologically-important reef fish behavior, delivered at the level of aggregations, instead of individual fish tracks that have been documented previously. The significance of this observation on sonar performance associated with target detection in the presence of fish clutter is discussed based on analyses of echo intensity and statistics. Building on previous studies of long-range fish echoes, this study further substantiates the unique utility of such sonar systems as an ecosystem monitoring tool, and illustrates the importance of considering the impact of the presence of fish on sonar applications.

The effects of fish feeding by visitors on reef fish in a Marine Protected Area open to tourism

Abstract: Coral reef-based tourism has risen sharply across the globe, coupled with an increase in fish feeding by visitors. Studies indicate that fish feeding is one of the leading causes of changes in distribution patterns, abundance, the structure of marine fish communities, and fish behavior. The aim of this study was to determine the effect of human presence and fish feeding on the behavior of reef fish by conducting in situ experiments in tide pools in a Marine Protected Area located at the northern limit of the Abrolhos Bank in the South Atlantic Ocean. Eight feeding sessions were conducted and filmed, resulting in a total of 160 minutes of video footage. Each filming session recorded four different experimental conditions alternating between human presence, human absence, and fish feeding. Our findings suggest that fish feeding may cause changes in fish behavior, such as habituation to human presence, conditioning to fish feeding, increased aggressiveness, attacks on humans, and short-term changes in species distribution. The continuation of fish feeding over time can cause an increase in the size of the populations of species that consume food provided during feeding and consequently trigger changes in the structure of communities.

Effects of tidal current-induced flow on reef fish behaviour and function on a subtropical rocky reef

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 559:175-192 (2016) - DOI: https://doi.org/10.3354/meps11918 Effects of tidal current-induced flow on reef fish behaviour and function on a subtropical rocky reef Linda Eggertsen1,*, Linus Hammar2, Martin Gullström3 1Department of Ecology, Federal University of Rio de Janeiro, 21941902 Rio de Janeiro, Brazil 2Department of Energy and Environment, Chalmers University of Technology, 412 96 Gothenburg, Sweden 3Department of Ecology, Environment and Plant Sciences, Stockholm University, 114 18 Stockholm, Sweden *Corresponding author: eggertsen.linda@gmail.com ABSTRACT: Tidal currents are important features in reef environments with high tidal range. Such current-influenced areas can be attractive for fish due to transport of nutrients and food items. Biological sampling, however, is difficult in these environments and it remains poorly understood to what degree strong currents actually shape tropical and subtropical reef fish communities. We used remote underwater video to investigate effects of flow velocity on fish across the tidal cycle at a rocky reef in southern Mozambique. Fish were recorded during flow velocities ranging from 0 to 1.44 m s-1. Current flow velocity had no significant effect on the benthic fish assemblage, while increasing flow velocity had a negative effect on pelagic fish abundance and influenced trophic group composition. Limits for tolerated flow velocity on the pelagic assemblage were species-specific, with the highest resistance for larger predatory fish using subcarangiform swimming. Flow velocity had significant positive effects on size of Caranx spp., showing that smaller individuals had lower tolerance to flow than larger conspecifics. Planktivorous pomacentrids and monodactylids were very abundant in flows up to 0.5 m s-1, suggesting that the area functions as an important foraging ground for planktivorous fish up to this flow velocity, while abundance of barracudas Sphyraena spp. was higher in moderate currents compared to slack water. For the benthic assemblage, benthic structures seemed to provide sufficient flow refuge for fish throughout the tidal cycle, highlighting the importance of structural complexity for benthic fish in this environment. Fish assemblages on reefs subjected to strong tidal currents might therefore be sensitive to habitat modifications. The ecological importance of tidal currents should be considered in marine management. KEY WORDS: Rocky reef · Reef fish · Tidal current · Water flow · Subtropical Full text in pdf format Supplementary material PreviousNextCite this article as: Eggertsen L, Hammar L, Gullström M (2016) Effects of tidal current-induced flow on reef fish behaviour and function on a subtropical rocky reef. Mar Ecol Prog Ser 559:175-192. https://doi.org/10.3354/meps11918 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 559. Online publication date: November 09, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Effects of elevated CO2 on predator avoidance behaviour by reef fishes is not altered by experimental test water.

Pioneering studies into the effects of elevated CO2 on the behaviour of reef fishes often tested high-CO2 reared fish using control water in the test arena. While subsequent studies using rearing treatment water (control or high CO2) in the test arena have confirmed the effects of high CO2 on a range of reef fish behaviours, a further investigation into the use of different test water in the experimental arena is warranted. Here, we used a fully factorial design to test the effect of rearing treatment water (control or high CO2) and experimental test water (control or high CO2) on antipredator responses of larval reef fishes. We tested antipredator behaviour in larval clownfish Amphiprion percula and ambon damselfish Pomacentrus amboinensis, two species that have been used in previous high CO2 experiments. Specifically, we tested if: (1) using control or high CO2 water in a two channel flume influenced the response of larval clownfish to predator odour; and (2) using control or high CO2 water in the test arena influenced the escape response of larval damselfish to a startle stimulus. Finally, (3) because the effects of high CO2 on fish behaviour appear to be caused by altered function of the GABA-A neurotransmitter we tested if antipredator behaviours were restored in clownfish treated with a GABA antagonist (gabazine) in high CO2 water. Larval clownfish reared from hatching in control water (496 µatm) strongly avoided predator cue whereas larval clownfish reared from hatching in high CO2 (1,022 µatm) were attracted to the predator cue, as has been reported in previous studies. There was no effect on fish responses of using either control or high CO2 water in the flume. Larval damselfish reared for four days in high CO2 (1,051 µatm) exhibited a slower response to a startle stimulus and slower escape speed compared with fish reared in control conditions (464 µatm). There was no effect of test water on escape responses. Treatment of high-CO2 reared clownfish with 4 mg l−1 gabazine in high CO2 seawater restored the normal response to predator odour, as has been previously reported with fish tested in control water. Our results show that using control water in the experimental trials did not influence the results of previous studies on antipredator behaviour of reef fishes and also supports the results of novel experiments conducted in natural reef habitat at ambient CO2 levels.

Molecular signatures of transgenerational response to ocean acidification in a species of reef fish

Ocean acidification impairs reef fish behaviour. This study shows offspring of spiny damselfish sensitive to high CO2 levels have different brain molecular responses to those of tolerant individuals, suggesting individual variation may allow adaptation. The impact of ocean acidification on marine ecosystems will depend on species capacity to adapt1,2. Recent studies show that the behaviour of reef fishes is impaired at projected CO2 levels3,4; however, individual variation exists that might promote adaptation. Here, we show a clear signature of parental sensitivity to high CO2 in the brain molecular phenotype of juvenile spiny damselfish, Acanthochromis polyacanthus, primarily driven by circadian rhythm genes. Offspring of CO2-tolerant and CO2-sensitive parents were reared at near-future CO2 (754 μatm) or present-day control levels (414 μatm). By integrating 33 brain transcriptomes and proteomes with a de novo assembled genome we investigate the molecular responses of the fish brain to increased CO2 and the expression of parental tolerance to high CO2 in the offspring molecular phenotype. Exposure to high CO2 resulted in differential regulation of 173 and 62 genes and 109 and 68 proteins in the tolerant and sensitive groups, respectively. Importantly, the majority of differences between offspring of tolerant and sensitive parents occurred in high CO2 conditions. This transgenerational molecular signature suggests that individual variation in CO2 sensitivity could facilitate adaptation of fish populations to ocean acidification.

Observer presence may alter the behaviour of reef fishes associated with coral colonies

AbstractAlthough underwater visual census (UVC) is the most frequently used technique for quantifying reef fish assemblages, remote video analysis has been gaining attention as a potential alternative. In the South Atlantic Ocean, Millepora spp. (class Hydrozoa) are the only branching coral species; however, little is known about the ecological role that they play for reef fish communities. We compared these two observation methods (remote video and UVC) to estimate reef fish abundance and species richness associated with colonies of the fire‐coral Millepora alcicornis at Tamandaré Reefs, Northeast Brazil. Additionally, the two different techniques were used to compare species behaviour in association with fire‐corals in order to examine the biases associated with each technique and provide useful information for behavioural ecologists studying fish–coral associations. There were no differences in reef fish abundance or species richness sampled by remote video or UVC. However, a significant difference in the behaviour of associated fish was recorded between the two methods. In the presence of a diver carrying out a UVC, fish were observed spending more time sheltered amongst the coral branches compared with passively swimming on coral colonies with the remote video technique. Specifically, on the remote video recordings agonistic interactions between fish and passive swimming accounted for 33.3% and 22.2% of the census time, respectively. By comparison, when observed by a diver fish spent 34.8% of their time sheltering amongst the coral branches. We demonstrate that both techniques are similarly effective for recording fish abundance and species richness associated with fire‐corals. However, differences were observed in the ability of each method to detect the behaviour of coral‐associated fishes. Our findings show that behavioural ecologists studying complex fish–coral associations need to ensure that their aims are clearly defined and that they choose the most appropriate technique for their study in order to minimize methodological biases.

Are Abrolhos no-take area sites of naïve fish? An evaluation using flight initiation distance of labrids

ABSTRACT Fishing pressure affects the behavior of reef fish, especially of fishery-targeted species. In this context, it is critical to understand if fish behavior is preserved in no-take areas (NTAs), which are considered the best instrument for the recovery of fish stocks. Comparing the flight initiation distances (FIDs) of fish inhabiting multiple-use areas (MUAs), where fishing is allowed (including spearfishing), and NTAs is a useful approach to test whether NTAs can be effective as fish refuges. Here, we compared whether the FIDs of two target (Sparisoma axillare and Scarus trispinosus ) and one non-target (Halichoeres poeyi ) labrids are greater in the MUAs than in the NTAs. We also investigated whether group size (GS) and body size (BS) exert any effect on the FID. We sampled four MUAs and four NTAs in the Abrolhos Bank (Brazil). We found that only for the targeted species FID was shorter inside the NTAs and that the BS had a positive effect on the FID of all species. The GS and BS of the fish are greater in the NTAs than in the multiple-use areas only for S. trispinosus . Our study shows that fish, especially those species that are fishery targets, display an avoidance behavior against spearfishermen likely as a consequence of fishing pressure. We suggest that the NTAs in Abrolhos are not only important sites for the recovery of fish stocks but also possibly act as a repository area of naïve fish (fish that allow human approach), for reefs open for fishing.

Small-Boat Noise Impacts Natural Settlement Behavior of Coral Reef Fish Larvae.

After a pelagic larval phase, settlement-stage coral reef fish must locate a suitable reef habitat for juvenile life. Reef noise, produced by resident fish and invertebrates, provides an important cue for orientation and habitat selection during this process, which must often occur in environments impacted by anthropogenic noise. We adapted an established field-based protocol to test whether recorded boat noise influenced the settlement behavior of reef fish. Fewer fish settled to patch reefs broadcasting boat + reef noise compared with reef noise alone. This study suggests that boat noise, now a common feature of many reefs, can compromise critical settlement behavior of reef fishes.

Local fishing influences coral reef fish behavior inside protected areas of the Indo-Pacific

Fishing is altering aquatic ecosystems through changes in the abundance, species composition and behavior of target species. Changes in fish behavior have received relatively little attention, despite significant evidence of behavioral change driven by human impacts mediating function and processes in terrestrial ecosystems, and emerging evidence that the same is true in marine systems even within marine reserves. Here, we measured the wariness of two families of coral reef fishes in both fished areas and marine reserves embedded within a fished seascape along an exploitation gradient ranging from wilderness sites (Chagos) to heavily fished areas (the Philippines). We used linear mixed effect models to identify relationships between fish flight initiation distance (FID) and fishing pressure, fish size, habitat complexity and life-history stage. Critically, fish FID increased with fishing pressure both in fished areas and inside marine reserves. These results imply that as fishing pressure increases in adjacent areas, progressively greater fish wariness may reduce the magnitude of some ecosystem functions within small marine reserves.