Parrotfish

Abstract

Animals often occupy home ranges where they conduct daily activities. In many parrotfishes, large terminal phase (TP) males defend their diurnal (i.e., daytime) home ranges as intraspecific territories occupied by harems of initial phase (IP) females. However, we know relatively little about the exclusivity and spatial stability of these territories. We investigated diurnal home range behavior in several TPs and IPs of five common Caribbean parrotfish species on the fringing coral reefs of Bonaire, Caribbean Netherlands. We computed parrotfish home ranges to investigate differences in space use and then quantified spatial overlap of home ranges between spatially co-occurring TPs to investigate exclusivity. We also quantified the spatial overlap of home ranges estimated from repeat tracks of a few TPs to investigate their spatial stability. We then discussed these results in the context of parrotfish social behavior. Home range sizes differed significantly among species. Spatial overlap between home ranges was lower for intraspecific than interspecific pairs of TPs. Focal TPs frequently engaged in agonistic interactions with intraspecific parrotfish and interacted longest with intraspecific TP parrotfish. This behavior suggests that exclusionary agonistic interactions may contribute to the observed patterns of low spatial overlap between home ranges. The spatial overlap of home ranges estimated from repeated tracks of several TPs of three study species was high, suggesting that home ranges were spatially stable for at least 1 month. Taken together, our results provide strong evidence that daytime parrotfish space use is constrained within fixed intraspecific territories in which territory holders have nearly exclusive access to resources. Grazing by parrotfishes maintains benthic reef substrates in early successional states that are conducive to coral larval settlement and recruitment. Behavioral constraints on parrotfish space use may drive spatial heterogeneity in grazing pressure and affect local patterns of benthic community assembly. A thorough understanding of the spatial ecology of parrotfishes is, therefore, necessary to elucidate their functional roles on coral reefs.

A new study by researchers from the University of Texas and California Polytechnic State University documented herbivorous fishes feeding on fish fecal pellets off the coast of Bonaire.  This has never been recorded in the Caribbean before and provides a deeper understanding of nutrient recycling and insight into the diverse diets of fishes who work to keep the local coral reefs healthy.

Blue parrotfish (Scarus coeruleus). Photo credit: Marion Haarsma

Coral reefs are one of the most diverse ecosystems on the planet, but they are also limited in nutrients. So, nutrient recycling is a vital part of supporting such reef organisms and their biodiversity. Organisms can’t process all the nutrients from the food they eat, so some of these nutrients come out in their poop. A new study documented a unique upcycling technique, previously unknown within the Caribbean, herbivorous fish feeding on fish feces.

Parrotfishes and surgeonfishes are often praised as the great caretakers of coral reefs, feeding on reef algae and keeping overgrowth in check, which indirectly promotes healthy coral recruitment and growth.  Although it was previously known that Caribbean parrotfishes and surgeonfishes also fed off other food sources, such as cyanobacteria, sponges, and even corals themselves, a recent study added fish feces to this list.

The Study

This collaborative effort was co-led by Hannah Rempel, a Ph.D. student from University of Texas Marine Science Institute and Abigail Siebert, a former undergraduate student from California Polytechnic State University. They studied the foraging rates of parrotfishes and surgeonfishes on fish fecal matter. Because they found that over 99% of feces they consumed were from the Brown Chromis (Chromis multilineata), a plankton eating fish, they also observed Brown Chromis feces to see what other reef fish ate them and studied the nutritional value of these feces. The study was conducted in 2019 between June and September, across six dive sites along the western shores of Bonaire.  This research is the first of its kind within the Caribbean and paves the way for continued exploration into the topic.

Fecal pellet. Photo credit: Hannah Rempel

The Results

Throughout this study, researchers documented that almost 85% of the observed fecal pellets were ingested by fish with over 90% consumed by parrotfish and surgeonfishes alone. “Compared to algae, these fecal pellets are rich in a number of important micronutrients. Our findings suggest they may be an important nutritional supplement in the diets of these fishes” stated Rempel. Taking a closer look at the fecal matter itself, researchers found that these pellets had higher values of proteins, carbohydrates, total calories, and important micronutrients when compared to most algae.  Therefore, consuming fecal matter may play an important role in nutrient transfer within the marine environment.

Future Research

Understanding the intricate dynamics within coral reefs provides information management authorities need to safeguard these environments more effectively. These results highlight the importance of the consumption of fecal matter in upcycling micronutrients, although there is still much to be learned about the nutritional content of other food sources, such as algae mats, cyanobacteria, sponges and corals.  Fish feces may play a vital role in nutrient supply within the reef environment, emphasizing the need for further insight into this topic moving forward.

For more information you can find the full report on the DCBD by using the link below.

More info in the Dutch Caribbean Biodiversity Database

Published in BioNews 53

Parrotfishes can often be observed consuming fish feces on coral reefs. Our recent study highlights the nutritional value of these feces to parrotfishes.  Four of the five most common speciesa t our study sites (Bonaire, Caribbean Netherlands) consumed feces, mostly from Chromis multilineata. Despite being infrequent (<4% total bites), we estimate that coprophagy may contribute ~27% of the carbon obtained by parrotifhses while foraging on preferred benthic substrates. Chromis feces also have higher protein and lipid conetents and lower C:N:P ratios than other foraging targets (algae and cyanobaceteria). Coprophagy is, thereofre, likely an important nad understudied component of parrotfish nutrition.

Read more at: https://www.jstor.org/stable/48657233

https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.3657

Abstract

Parrotfishes and surgeonfishes are major Caribbean herbivores that primarily graze reef algae and thereby play an important functional role in indirectly promoting coral recruitment and growth. Yet, an emerging body of research suggests that these nominal herbivores graze on a diverse array of other food sources and researchers have questioned whether they may target more nutrient-dense foods growing within or upon algae, such as cyanobacteria. In this study, we investigated the speciesspecific foraging rates of parrotfishes and surgeonfishes on Brown Chromis (Chromis multilineata) fecal pellets compared to other major dietary items. We found that almost 85% of observed fecal pellets were ingested by fishes and that over 90% of ingested fecal pellets were consumed by parrotfishes and surgeonfishes alone. While there were species-specific differences in the levels of feces consumption (coprophagy), we found that all three surgeonfishes (Acanthurus chirurgus, A. coeruleus, and A. tractus) and six of the nine of parrotfish species surveyed (Scarus coeruleus, S. iseri, S. taeniopterus, S. vetula, Sparisoma aurofrenatum, and S. viride) consumed C. multilineata feces. To better understand the nutritional value of this behavior, we analyzed the composition of proteins, lipids, carbohydrates, total calories, and micronutrients in C. multilineata fecal pellets and compared these to published values for other food sources targeted by these fishes. Our findings suggest that these fecal pellets may have higher values of proteins, carbohydrates, total calories, and important micronutrients, such as phosphorus, compared to various macroalgae and the epilithic algae matrix, though comparable or lower values compared to cyanobacteria. To our knowledge, this is the first study to document coprophagy by tropical herbivorous fishes in the Caribbean region. This research advances our understanding of the foraging ecology of nominally herbivorous fishes and highlights the importance of fish feces as a nutritional resource on coral reefs.

The direct and indirect impacts of the increase in human population, in particular the growing demand for food, as well as various aspects of climate change pose threats to the abundance of parrotfishes (Scarinae), the main coral reef grazers. One way to reduce fishing is by forming marine protected area (MPA). MPAs tend to increase the abundance of marine fish. Well-managed MPA, with effective protection from fishing, could also benefit sex-changing fish populations. The objectives of this research are to assess effects of MPAs on parrotfish abundance and biomass and how do parrotfish abundance and size in the different life phases differ between sites within MPAs and outside MPAs. Fish surveys were conducted in eight Caribbean countries (Antigua, Bonaire, Barbados, Curaçao, Dominican Republic, Jamaica, St. Lucia and St. Vincent and Grenadines (SVG)) using an underwater visual census technique. The differences between parrotfish density and size within and outside MPAs were assessed. Mean parrotfish numerical density was slightly higher at MPA sites than at non-MPA sites but this was not significant. A significant difference was found between parrotfish biomass within and without the MPAs. The abundance biomass comparison (ABC) results showed that out of 33 MPA sites, 79% had a positive index and 21% a negative W-index value. In contrast, only 49% of non-MPA sites surveyed had a positive W-index. Sites within an MPA generally had higher mean parrotfish sizes than those outside the MPA, except for the juvenile phase. The present results reinforce the belief that parrotfish abundance and biomass, which where depleted by fishing, can be increased through applying significant levels of protection. However further research is needed on the effectiveness and duration of protection which are necessary to produce desired levels of improvement in parrotfish abundance, biomass and size.

The stoplight parrotfish, Sparisoma viride, is one of the dominant herbivores on the reefs of Bonaire. The effects of macroalgae herbivory have been well documented but the potential of S. viride to act as a shuttle for zooxanthellae remains unknown. Although coral is not considered a food item of S. viride they occasionally bite living tissue off of colonies of the scleractinians Montastrea annularis and Colpophyllia natans. Coral tissues contain large amounts of symbiotic dinoflagellates of the genus Symbiodinium, commonly referred to as zooxanthellae. Symbiodinium may be the key primary producer of the reef ecosystem and are found almost exclusively in symbiotic relationships with cnidarians. It is the aim of this article to examine the potential role of S. viride as a vector for transport of Symbiodinium throughout the reef environment as a result of parrotfish white spot biting. The purpose of coral biting is not known but territoriality is suspected in focused biting. Depending on the effect of parrotfish ingestion on the Symbiodinium cells, parrotfish white spot biting behavior could result in transport of Symbiodinium throughout the reef environment, increasing the genetic diversity of zooxanthellae populations.

This student research was retrieved from Physis: Journal of Marine Science I (Fall 2006)19: 33-37 from CIEE Bonaire.

Parrotfish promote coral growth by controlling the abundance of algae on coral reefs. Although the importance of parrotfish herbivory on coral reefs has been noted; the feeding behavior of parrotfish is not fully understood. What is known is that territorial parrotfish defend the reef slope, forcing nonterritorial parrotfish to move to shallower water to feed. Ecological studies of predator-prey interactions suggest a correlation between risk and foraging behavior. The parrotfish on the reefs in Bonaire demonstrate a risky feeding behavior in the shallow sub-tidal zone that increases the risk of predation by osprey. A chain transect was used to determine the percent cover of algae in the shallow sub-tidal zone and reef flat. The percent cover of algae is greater in the shallow sub-tidal zone, meaning there is more food available in the habitat with higher risk of predation. In the shallow subtidal, parrotfish feed on turf algae and Padina in the same proportion as they occur on the benthos, meaning parrotfish are not feeding preferentially when in the shallow sub-tidal. To determine if there were diurnal feeding patterns in the shallow sub-tidal, observations were made 3 times per day. Initial phase parrotfish used the shallow sub-tidal zone more than terminal phase parrotfish and yellowtail parrotfish were the most abundant species. The species and phase that were most abundant may be a reflection of parrotfish populations on the reefs of Bonaire or a higher degree of crypsis. Tide levels had an impact on when the parrotfish could feed. Though most feeding occurred during morning and noonday hours, high and transitional tides were only found during these two time frames, which may explains the diurnal feeding behavior.

This student research was retrieved from Physis: Journal of Marine Science V (Spring 2009)19: 27-31 from CIEE Bonaire.

Many marine organisms use mucus to catch food, clean themselves, or for protection from predators. Some species of parrotfish (Family Scaridae) use mucus to build cocoons around themselves at night, which is thought to be a form of protection. Although there are reports of parrotfish constructing mucus cocoons, little is known about which specific species produces cocoons, where on the reef cocoons are used, or how prevalent the behavior is in Bonaire, N.A. The purpose of this study was to determine which species and phases of parrotfish construct cocoons, the distribution of cocoons from the reef slope to the shallow subtidal, and whether cocoons are being used for protection from predators. Observations took place between Oct. – Nov. 2009, after 23:00 h. Six depths were surveyed for parrotfish (1, 3, 6.5, 10, 15, and 20 m) and surveys were standardized by time. A guide diver assisted in keeping time, recording predators, and maintaining depth. Seven to 10 min was spent at each depth starting at 20 m and working up to 1 m. This study provides information on the nighttime ecology of parrotfish, which may be important for conservation of the species. During this study, two species of parrotfish, Scarus taeniopterus (princess parrotfish) and Scarus vetula (queen parrotfish), were found in cocoons; cocoons were only built along the reef slope, and none were found on the reef flat. Only terminal phase S. taeniopterus were found in cocoons, whereas terminal and initial phase S. vetula were found in cocoons.

This student research was retrieved from Physis: Journal of Marine Science VI (Fall 2009)19: 53-57 from CIEE Bonaire.

Parrotfish are a common and important component of the fringing reefs ecosystem surrounding Bonaire, N.A. In the reef environment, large herbivores like parrotfish graze on macroalgae, allowing for higher coral diversity and abundance. This research studies habitat use among five common species of parrotfish, Scarus guacamaia, Sparisoma viride, Scarus taeniopterus, Sparisoma aurofrenatum, and Scarus vetula found on the leeward coast of Bonaire. The study was performed between Playa Lechi and Something Special dive sites, where transect tapes were placed at three depths representing different habitat types (shallow ridge, reef crest, and reef slope). After a brief recovery period (~ 1 hour), abundances of initial phase and terminal phase parrotfish were determined using SCUBA during midday, and again at night. Parrotfish density was higher during the day than at night and was significantly different among the three depths. Fisher’s PLSD post-hoc test showed that parrotfish density was significantly higher at 12 m than at 1 or 20 m. During the day, density of initial phase parrotfish was significantly higher than terminal phase, but there was no difference among the three depths. At night, there was no difference between the density of initial phase and terminal phase parrotfish, but there were more parrotfish found at 12 m than at 1 or 20 m. Based on the results of this study, more parrotfish are spotted during the day, parrotfish are found most often at 12 m during the night and day, and there are more initial phase parrotfish than terminal phase at all three depths during the day. Overall, significant findings include information about parrotfish habitat and differences between phases, with the additional note that 12 m depth seems to be an important habitat range for parrotfish in Bonaire.

This student research was retrieved from Physis: Journal of Marine Science VI (Fall 2009)19: 1-6 from CIEE Bonaire.

Most animals are active either during the day or night, and at twilight, nocturnal and diurnal animals alike engage in behaviors to avoid predators, seek shelter, defend territory, or feed. Herbivorous fishes on coral reefs, such as parrotfishes, forage throughout daylight periods due to reliance on light and low nutrient content of algae. At sunset, parrotfishes seek cover to avoid predation during the night, resulting in less feeding and more aggressive behavior. This study compared how initial phase (IP) and terminal phase (TP) Princess parrotfish (Scarus taeniopterus) allocate time between daylight and sunset periods, specifically regarding feeding and aggressive behavior, on the fringing reefs of Bonaire, Dutch Caribbean. Using SCUBA, individual S. taeniopterus between 11 and 14 m depth were followed for 5 min after a 1 min acclimatization period, and time spent on each behavior was recorded. A two-way analysis of variance (ANOVA) was used to compare the amount of time S. taeniopterus spent feeding and in aggressive interactions between day and sunset periods, with phase and time of day as factors. Fish of both phases had a higher mean percent time feeding and a lower mean percent time being aggressive in the morning than at sunset. There was a significant difference in mean percent time feeding between phases, and TP fish had a significantly higher mean percent time being aggressive than IP fish. The changes in behavior found in this study increase the success of S. taeniopterus finding and keeping quality nighttime resting locations.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 45-51 from CIEE Bonaire.