feeding behaviour

Abstract

The killer whale (Orcinus orca) is a cosmopolitan cetacean distributed worldwide. Extensive studies have described its ecology and behavior across multiple polar and temperate regions. On the other hand, there is limited information on the distribution, ecological roles, and abundance of killer whales in tropical and subtropical regions. Herein, we build on previous work to update information on the spatiotemporal distribution, exploitation, and natural history of killer whales in the Caribbean Sea. We also document new records on their interaction with other species and human activities. We collated 385 records from the literature, online biodiversity information systems, the Internet (social networks and video-hosting websites), and citizen science-based initiatives. Records included sightings (87.3%), intentional captures (10.6%), bycatch (0.3%), and strandings (1.8%). Data primarily originated from research projects/activities (57%) and citizen-science-based initiatives (43%). Records were distributed in the eastern Caribbean (39.5%), the southern Caribbean (19.7%), the Greater Antilles (19.2%), the Bahamian Region (13.0%), Central America (6.8%), and eastern Florida (1.8%). Killer whales were recorded year-round, but most data were reported between March and August (59.6%). The scarcity of records in Central America could reflect true lower densities in the region, lower observation effort, or a combination of the two. Because of the paucity of data, this study supports the growing importance of citizen-science initiatives to document the occurrence and ecology of this species in the Caribbean. Our dataset also confirms the occasional and widespread occurrence of killer whales throughout the Caribbean Sea. Potential low densities and limited predictability of their occurrence hinder dedicated research on this species.

Bonaire is home to the largest natural flamingo reserve in the western hemisphere, housing one of the four remaining crucial breeding grounds in the world and the primary breeding ground of the Americas. Flamingos filter feed on gastropods, crustaceans and chrinomids in salt water lakes and ponds. This study examined flamingo distribution and feeding behavior in relation to changing salinity levels in condenser ponds used for salt production on Bonaire, Netherland Antilles. Flamingo density was found to be highest (44.4-172.7birds/km2 ) in ponds with the highest salinity (184-205g/l) among the ponds tested, followed by ponds with the lowest salinity (55 g/l). Ponds with an intermediate salinity (84-154 g/l) hosted significantly fewer birds (0-1.6 birds/km2 ). The type of feeding behavior used by flamingos was found to be related to water depth and salinity range and could possibly be explained by differences in prey found at different salinities and depths; however, this specific question was only addressed in a qualitative manner in this study. Grubbing was most prevalent in high salinity ponds while skimming occurred with higher frequency in low salinity ponds. Because grubbing is generally used to feed on pond bottoms results suggest that prey items in high salinity ponds may be densest at the bottom and probably consist of chrinomids such as brine fly pupae. Conversely, skimming is used in shallower water and its prevalence in low salinity ponds indicates that prey is concentrated in the water column and best caught by filter feeding mechanisms.

This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 1-5 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.

Foraging success is affected by choice of feeding association, color phase, and habitat type. Bar jacks (Caranx ruber) exhibit a number of feeding associations, changes in coloration from silver to dark brown/black, and utilize different habitat types within the fringing reef ecosystem for feeding. The objective of this study is to determine if foraging success is affected by 1) feeding association utilized (individual, conspecific, or multispecies groups) 2) color (black or silver) or 3) habitat type (reef flat or reef slope). Observations of C. ruber were conducted at two dive sites on the fringing reef of Bonaire using SCUBA. The number of bites min-1 was used as a measure of foraging success. Analysis of results shows that C. ruber has significantly greater foraging success when feeding alone and in multispecies groups as opposed to feeding with conspecifics. Dark brown/black C. ruber have double the feeding rate as that of silver and habitat type did not have an affect on C. ruber foraging success. In conclusion, foraging success of C. ruber, measured in bites min-1 , is affected by choice of feeding association and coloration, but is not affected by choice of habitat.

This student research was retrieved from Physis: Journal of Marine Science V (Spring 2009)19: 10-13 from CIEE Bonaire.

The spotted moray eel, Gymnothorax moringa, is one of the most abundant moray eels found in the coastal waters of Bonaire, N.A. However, little is known regarding the factors that contribute to its choice of habitat, behavior, and times of activity. Contradictory evidence has been reported for many species of Gymnothorax as to whether they are nocturnal or diurnal, yet little is known concerning color and size, which may be correlated to diet and choice of habitat. This study sought to determine how size, behavior, and color correlate with reef flat and reef slope habitats and at what time (morning or evening) G. moringa is most active. Observations of G. moringa were conducted in the westward coastal waters of Bonaire. A “U”-shaped search pattern was utilized in locating spotted moray eels in 5 adjacent study areas extending perpendicular from the shore to a depth of ~ 15 m. Once an individual was located behavior, jaw size, and color, were recorded in order to assess differences among individuals on differing habitats (reef flat or reef slope), and times of day (morning: 6:00 - 7:30 or evening: 18:00 – 19:30). G. moringa was found to be in greater abundance on the reef flat in the evening displaying exposed venting behavior and individuals were predominantly white in coloration. In the morning G. moringa were found to be in greater densities on the reef slope, displaying foraging behavior, and were predominantly black in coloration. Representatives of all size classes were distributed on the reef flat regardless of time, however, small individuals were not observed on the reef slope in the evening.

This student research was retrieved from Physis: Journal of Marine Science VI (Fall 2009)19: 7-13 from CIEE Bonaire.

Bioinvasions are defined as the establishment of a species in an area where it has not existed previously. Usually the result of an anthropogenic introduction, bioinvasions pose a great threat to coral reef ecosystems. One example of an anthropogenically-induced bioinvasion is that of the lionfish (Pterois spp.) to the Atlantic basin. First reported in Bonaire, N.A. in 2009, the Indo-Pacific lionfish has spread rapidly, with 177 fish reported as of 31 March, 2010. One of the purposes of this study was to document interspecific interactions of lionfish with prey and non-prey fish species at twilight, when lionfish are reported to be active. Interactions were video recorded for further analysis. Additionally, stomach contents of lionfish on Bonaire were analyzed and compared to lionfish from a similar study in the Bahamas, which determined that as lionfish size increases, so does the % volume of fish in their diet. Lionfish, collected by the Bonaire National Marine Park and volunteers, were categorized according to total length for use in this study. Prey items found in the stomach contents were identified to the lowest possible taxon. It was hypothesized that as the size classes of lionfish increased, an increase in the % volume of fish and a decrease in the % volume of shrimp in their diet would be observed. Lionfish were observed interacting more with potential prey items than non-prey items based on video analysis. Data analysis of stomach content found that as lionfish size increased, the amount of fish by % volume increased from 60% volume in the smallest size class to 93% volume in the largest size class. This study showed that as lionfish size increases, they rely more heavily on fish as a part of their overall diet, and the fish they are consuming are those they are observed interacting with most.

This student research was retrieved from Physis: Journal of Marine Science VII (Spring 2010)19: 27-33 from CIEE Bonaire.

Worldwide, fisheries produce ~27 million tons of by-catch yr -1 . By-catch is defined as unwanted fish that are accidentally caught, or discarded carcasses of target species. In Bonaire, N.A., by-catch is produced on a relatively small scale, by artisanal fishermen cleaning fish that they caught and discarding the remains back into the ocean. This study examines the feeding behaviors of fish in Bonaire and the effect fishermen’s by-catch has on these behaviors, and also investigates the potential for fish to learn about sites of by-catch input. This study was performed in two parts, the first assesed the effects of established by-catch sites, while the second part focused on learning behaviors of fish. Bites per minute, time of arrival to the food source and fish population data was collected at sites along Kaya Playa Lechi where fishermen were present daily. The same data was collected 30 m away from the fishermen at simulated by-catch sites, as well as at control sites where no by-catch was present. In part II, the discarding of fish was simulated at sites that do not receive it on a normal basis, to obtain observations on fish reactions to a new food source. It was found that densities and biodiversity were significantly greater at by-catch treatments vs. control treatments for part I. Bites min-1 was greatest when by-catch was present and the time of arrival data showed that the greatest proportion of fish arriving for the fishermen’s by-catch was within the first 15 s. For part II, densities and biodiversity were greater at control treatments than at simulated by-catch treatments. Bites min-1 was greater at simulation treatments, and there was a decrease in the time of arrival over the three day observation period. This data shows that relatively greater fish densities were seen at sites of food input, that fish were more aggressive when by-catch was present, and that fish can learn that to respond to sites with a consistent input of by-catch.

This student research was retrieved from Physis: Journal of Marine Science VII (Spring 2010)19: 21-26 from CIEE Bonaire.

Invasive species are often a detriment to the environment due to the lack of parasites, disease and natural predators in the invaded environment, which allows the population to explode. Pterois volitans were introduced into the eastern part of the Atlantic in 1980’s, and migrated to the southern Caribbean and in October 2009, lionfish were first documented on the island of Bonaire, Dutch Caribbean. The purpose of this study was to document the feeding ecology of lionfish by identifying and quantifying stomach contents of different size classes of lionfish found on the island using four different metrics- frequency of occurrence, percent by volume, percent by number and Index of Relative Importance (IRI). Of the 70 lionfish stomachs analyzed, there was a positive correlation between lionfish size and amount of fish consumed. Similarly, there was a negative trend seen with size class and the amount of shrimp found in the stomach contents. When IRI was used to compare feeding ecology of Bonaire lionfish to a Bahamas study, the top five ranked families of preyed differed. This study identifies major dietary trends of lionfish on Bonaire, and can be used to better understand the feeding ecology and diet habits.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 38-43 from CIEE Bonaire.

Redlip blennies (Ophioblennius macclurei) are common reef fish in Caribbean coral reef environments. They are vitally important to reefs as primary consumers providing a link between algal production and secondary consumers. This research sought to discover the territorial interactions between O. macclurei and other reef species, as well as the amount of grazing pressure placed on reefs by Blennid presence. Videos were taken 2-3 times per week between 26 September and 4 November 2012, and were used to assess feeding behavior and territorial defense. The data collected has applications in monitoring reef energy transfer up the food web and the amount of grazing pressure placed on a reef. The average area grazed per day was found to be 1100.09 cm2 . Territoriality is useful to understand the complex relationships between population of reef fish and suitable territory area. It was found that blennies primarily hide from fish intruding into their territory, but will not allow others of the same species to overlap territories. The preferred substrates noted in the study were Diploria labyrinthiformis and turf algae. The findings have importance in blenny conservation by showing habitats preference. Findings also indicate to future researchers the importance of including small grazers in benthic studies.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 101-107 from CIEE Bonaire.