Coral reefs

Coral reef environments exhibit numerous ecological interactions between different organisms. The habitat structure of a healthy coral reef is composed of many different coral species, with various fish species inhabiting the reef. Coral reef studies often focus on a large spatial scale rather than smaller local scale environments within the reef. The objective of this study was to compare fish populations associated with the microhabitat surrounding individual coral heads of two different species. The purpose of this study was to determine if there were differences in fish abundance, fish species richness, and fish diversity between two massive stony corals, Diploria strigosa and Orbicella annularis. These two corals are common on many Caribbean reefs but are morphologically different; therefore, it was hypothesized that they would show differences between their associated fish assemblages. By conducting fish count observations on both D. strigosa and O. annularis, I was able to compare means between the coral associated fish populations using statistical tests. No statistically significant differences were found between these two coral species for mean fish abundance, species richness, or diversity. One possible explanation is that the larger scale reef environment and processes may have a significant effect on local fish populations found on individual coral heads. By studying the microhabitats of coral species and the associated fish assemblages, we can gain a better understanding of fish population dynamics of coral reefs across larger ecological scales—both regionally and globally

This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 61-69 from CIEE Bonaire.

El Niño Southern Oscillation (ENSO) events are known to bring high sea surface temperatures and in turn cause coral bleaching. The Fall 2015 ENSO event has had record breaking temperatures and has been severely detrimental to Pacific coral reef ecosystems. To gauge the effect this ENSO event would have on the Caribbean, this study looked at the frequency and severity of bleaching and paling, during this ENSO event. The bleaching was measured along a 2 m wide by 10 m long transect. Coral colonies along the transect were observed once a week for four weeks and the water temperature was recorded hourly. At the end of data collection, the overall number of corals experiencing bleaching was recorded and the percent difference in paling and bleaching from week to week was measured. At the end of the four weeks it was found that 60 out of 192 coral colonies were experiencing some form of bleaching. By the fourth week there was no significant increase in bleaching, and paling had significantly increased until week four. This trend followed the decrease of water temperature from week one to week three with signs of coral recovery, but there was also evidence of water temperature starting to increase again by week four.. This study shows the resilience of Bonairean reefs and that this ENSO event may have a lesser affect on the Caribbean coral reefs compared to the Pacific.

This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 47-52 from CIEE Bonaire.

Marine sponges provide an important link between the benthic and pelagic environments of coral reef ecosystems, yet there is relatively little known about them. Past studies have indicated that depth and size could be contributing factors in tube sponge filter feeding strategies. This study investigated the effects of depth and size on pumping rate and filtering efficiency of Aplysina lacunosa, a common Caribbean reef sponge. At two different depths, several parameters of the sponges were measured: tube length, wall thickness, tissue volume, pumping rate (using fluorescein dye), and filtering efficiency (percent reduction in turbidity between the ostia and osculum). Water samples collected from the water column had similar food availabilities between the two depths. There was a positive relationship between sponge size and pumping rate but not filtering efficiency. Additionally, no relationship was found between depth and sponge pumping rate and filtering efficiency, which is consistent with my finding that food availability did not differ across depths. The filter feeding strategy of A. lacunosa may be unique in the context of other benthic filter feeders in that its pumping rate but not filtering efficiency is affected by size and that neither pumping rate nor filtering efficiency are affected by depth. Further investigations are needed to learn more about the biology of A. lacunosa and its significance to Caribbean coral reefs.

This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 40-46 from CIEE Bonaire.

Understanding predator-prey relationships gives greater insight into coral reef health. A recent study on predator-prey relationships linked the relative brain mass of predators and their prey. Predation pressure forces prey to use decision making skills that require higher cognition by inspecting and identifying predators and then adjusting their behavior to achieve the highest chance for survival. However, the predation pressure that prey face outweighs the pressure predators face to find a prey. This results in prey having larger relative brain masses than their predators. There is little data on relative brain mass of fishes with few natural predators such as Pterois volitans. This study compared the brain mass to body mass ratio of P. volitans, which have very few natural predators and thus very little predation pressure, to the brain mass to body mass ratio of their prey, possible predators, competitors, and taxonomically similar fish. This study also analyzed the response of lionfish to divers with nets in order to investigate their ability to recognize divers as predators. Lionfish did swim away from divers 56.5% of the time which indicates that lionfish might be able to recognize divers as predators. Lionfish had a significantly smaller relative brain mass than their predators, prey, and competitors, but was not significantly smaller than taxonomically similar fish. These results demonstrate that the morphological antipredator adaptation of venomous spines cause very little predation pressure. Thus, lionfish are not forced to use the same cognitive skills as other prey or predators and in turn have smaller relative brain masses.

This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 10-20 from CIEE Bonaire.

Marine anemones influence oceanic food webs, partake in symbiotic relationships with many marine phyla, and can prove detrimental to coral reef ecosystems in excess. Few descriptive studies have been conducted on anemone communities. The present study examined anemone abundance and diversity using fluorescence across reef habitats in a coral reef ecosystem for the first time on Bonaire, Dutch Caribbean. A total of 110 fluorescent anemones belonging to at least 9 species were documented. Anemones exhibited species-specific ranges in one or multiple reef habitats including the reef flat (2-6 m depth), reef crest (6-9 m depth), and reef slope (9-15 m depth). Four possibly unidentified species were documented. Fluorescent anemone abundance varied significantly between reef flat (5.5 ± 0.7 individuals) and reef crest (27.5 ± 6.4 individuals) habitats. Although fluorescent anemone diversity was highest on the reef flat and lowest on the reef slope, there was no significant difference among the reef habitats. The study contributed to current knowledge on fluorescent anemone ecology by documenting species habitat ranges. It suggested that among species and as a whole, anemones are habitatspecific. The results also provided habitat ranges for obligate anemone symbionts. The study may be valuable for a variety of scientific fields. Descriptive studies such as the present project in Bonaire facilitate the possible discovery of new and groundbreaking species and model organisms. Tracking distribution and diversity could also inform of anemone bleaching and serve as a bioindicator of reef health and climate change ramifications.

This student research was retrieved from Physis: Journal of Marine Science XIX (Spring 2016)19: 74-84 from CIEE Bonaire.

Raw photo material of the 2016 reef survey using the GCRMN method.

The 20 survey sites lie within the St. Eustatius National Marine Park, which surrounds the island from the high water mark to a depth of 30 meters.  To maximize comparability across the region, GCRMN data was collected solely from forereef habitats at depths ranging from 8 – 15 meters. Sites included the industrialized harbor area along with sites with perceived lower anthropogenic influence on the north and south ends of the island. For each site 5 transects were surveyed. Photographs were taken along the 5 transect lines set for counting fish, capturing 15 images per transect line. Download the summary data of the photo-analysis. See this report for details.

Please contact the DCBD administratorfor access to the raw digital photographs.

The goal of the Global Coral Reef Monitoring Network (GCRMN), an operational network of ICRI, the International Coral Reef Initiative, is to improve data collection, archiving and the network internal functioning for a better diffusion of information on coral reef development and to increase the support for regional and sub-regional cooperation.By applying the GCRMN monitoring methods for a second year, St Eustatius is now on the way to providing scientifically pertinent coral reef data to the Marine Park

The survey location is the St. Eustatius National Marine Park (SNMP), which surrounds the island from the high water mark to a depth of 30 meters.management and the Island Government. To maximize comparability across the region, GCRMN data was collected solely from fore reef habitats at depths ranging from 8 – 18 meters. An effort was made to include sites within the industrialized harbor area along with sites having perceived lower anthropogenic influence on the east, north and south sides of the island. Within the SNMP the 20 sites selected for 2015 were again monitored in 2016:

To follow the health of the coral reefs of Bonaire and Curacao a number of locations on each island are photographed each year since 1973. At each location a 3 m square at up to 4 different depths is recorded.

Please contact the DCBD administratorfor access to the raw digital photographs.

In the last three decades, Caribbean coral cover values have been declining from 50% to 10% cover Caribbean wide. Several studies have researched this decreasing trend and assessed coral reefs throughout the Caribbean. These assessments often identify the coral reef of Bonaire as one of the most pristine reefs and describe the leeward coast of Bonaire as one of the healthier reefs of the Caribbean. However, the outcomes of these studies are based on pooled data, collected from multiple depths and locations and are presented as being valid for an entire reef while they have often been collected on a very small number of locations on each island. In a study on the ecosystem services of the reefs of Bonaire, Meesters et al. (2014) suggested that coral reefs show large variation in ecological quality on a small scale. This report investigates this small-scale variation in coral reef quality on the leeward coast of Bonaire. On the leeward side, we sampled the coral reef every 500 meters resulting in a total of 115 sampling sites. On each location, the reef was sampled at two different depths (~5 and ~10 meters) following the zonation pattern from Bak (1977). The reef quality is assessed with the Reefbudget methodology described in Perry et al. (2012). Carbonate production, bioerosion, and net production is calculated in kg CaCO3 m-2 year-1 for each site and depth. The net carbonate production reveals the quality of a reef. A positive value indicates the reef is growing while a negative value means a reef or site is flattening. Cluster analysis and TukeyHSD tests are used to analyse the spatial distribution of coral communities and to test if areas show a significant difference in coral reef quality. The shallow reef (depth ~5 meters) in front of Kralendijk shows clear signs of degradation. The area has a significant lower coral cover (3%, p=0.05) and a mean net carbonate production of -0.40 kg CaCO3 m-2 year-1. We found the marine reserve to have the highest coral cover and net carbonate production. The shallow reef of the marine reserve net produces 3.64 kg CaCO3 m-2 year-1, and the fringing deeper reef (depth ~10m) 4.04 kg CaCO3 m-2 year-1. A previous study found a net production of 3.63 kg CaCO3 m-2 year-1 for 5m depth zone. For the 10m depth, net carbonate production was 9.53 kg CaCO3 m-2 year-1. Both values were measured at the “no dive reserve” of Bonaire in Perry et al. (2012). This study finds a lower production for the 10 meters zone, but comparable values for the shallow reef at 5 meters depth. However, the values of the Marine Reserve in this study are the highest of the leeward side of Bonaire. The reef shows a large variation in reef quality along the coastline Net carbonate production ranged from a minimum of -8.70 to a maximum of 50.85 kg CaCO3 m-2 year-1 for one transect. This range is much larger than the range found by Perry et al. (2013). Perry et al. (2013) found a minimum net carbonate production of -2.3 kg CaCO3 m-2 year-1 and a maximum of 16.68 kg CaCO3 m-2 year-1. Comparing the calculated net carbonate production values in this study with data from the Caribbean region, we found that the variation between sites on the leeward side of Bonaire shows similarity with the variation throughout the area. Net production of reefs on Belize, Jamaica, and St. Croix show values of 1.42, 1.2-1.8, and 0.9 kg CaCO3 m-2 year-1 respectively. These values are similar to the 5 meters reef at Klein Bonaire, the South, and the North of Bonaire with 1.09, 0.49, and 0.18 kg CaCO3 m-2 year-1 production respectively. This study reveals a difference in coral community composition between the North and the South of Bonaire. The 10 meter reef of North Bonaire is merely Merulinidae spp where the South of Bonaire is more diverse with a larger cover of Agariciidae spp. Overall turf cover is high across the entire coastline with for the 10 meter depth reef a mean of 36.4% (± 1.8) cover. The 10 meter reef in front of the city shows a higher mean turf algae cover of 50% cover. This study shows that the reef in front of the Kralendijk is in a poor state and is, with a net negative carbonate production, flattening in topographic complexity. The Marine Reserve shows the best net production values in both the 10 meters depth reef as the 5 meters depth reef. The variation between sites along the leeward side is large. This large variation proofs that it is not legitimate to assess an entire coastline based on a limited number of sites. While parts of Bonaire Marine Reserve can indeed be viewed as belonging to the most pristine in the Caribbean, other areas, e.g. in front of the city, show similarities with known