coral monitoring

With increasing stressors to coral reefs, defining tools that evaluate their dynamics and resilience is important to interpret system trajectories and direct conservation efforts. In this context, surveys must go beyond conven- tional monitoring approaches that focus on abundance and biomass of key groups and quantify metrics that better assess ecological processes and ecosystem trajectories. By measuring a variety of conventional (e.g. proportional cover of broad benthic groups, biomass of herbivorous fish) and complementary resilience-based metrics (e.g. algal turf height, coral recruitment rates, juvenile coral densities, herbivorous fish grazing rates), this study evaluated the ecosystem responses to community-based management in Fiji. The study was conducted across three paired tabu areas (periodically closed to fishing) and adjacent fished sites. Conventional metrics reflected no management effect on benthic or herbivorous fish assemblages. In contrast, the complementary metrics generally indicated positive effects of management, particularly within the benthos. Significant differ- ences were observed for turf height (33% lower), coral recruitment rate (159% higher) and juvenile coral density (42% higher) within areas closed to fishing compared to adjacent open reefs. In addition, turf height was in- versely related to coral recruitment and juvenile coral density, and longer turfs (≥5 mm) were more competitive in interaction with corals. These results emphasise that conventional metrics may overlook benefits of local management to inshore reefs, and that incorporating complementary resilience-based metrics such as turf height into reef survey protocols will strengthen their capacity to predict the plausible future condition of reefs and their responses to disturbances. 

Rehabilitating populations of Caribbean coral species that have declined in recent decades has become a management priority throughout the region, stimulating the development of new methodologies to arti cially reseed degraded reefs. Rearing lar- vae of ecologically important coral species appears a particularly attractive method to aid the recovery of degraded populations because genetic recombination could yield new genotypes better capable of coping with the altered conditions on modern Caribbean reefs. Well-developed elkhorn coral (Acropora palmata Lamarck, 1816) populations form dense thickets that contribute to the maintenance of healthy and productive reefs by providing shelter to a variety of other reef organisms (Gladfelter and Gladfelter 1978). After >95% of A. palmata populations were decimated by a disease beginning in the mid-1970s, this species was listed as critically endangered under the Red List of threatened Species (IUCN 2013) and restoration e orts were initiated throughout the region to assist its recovery (Young et al. 2012). In 2011, we collected gametes from eight A. palmata colonies in situ o Curaçao, which were subsequently cross-fertilized to generate larvae. Competent larvae were settled on clay tiles (Panel A) and reared in a ow-through land-based nursery for one year (Panels B–C), after which they were outplanted to a breakwater at 2–5 m depth (Panel D) [refer to Chamberland et al. (2015) for details on methodology]. Seven out of nine outplanted colonies survived and continued to grow in situ (Panels D–E), reaching a size of 30–40 cm diameter and 20–30 cm height after 4 yrs (Panel F). On 8 and 10 September, 2015, nine and 11 d after the full moon, two colonies were ob- served releasing gametes between 155 and 175 min after sunset (Panels G–H). is is the rst time that an endangered Caribbean Acropora coral species was raised from larvae and grown to sexual maturity in the eld. Indeed, only one other study has documented age and colony size at reproductive onset in a broadcast spawning scler- actinian coral reared from larvae (Baria et al. 2012). e relatively short time until onset of spawning (≤4 yrs) observed for A. palmata shows that recovery of degraded coral populations by enhancing natural recruitment rates may be practicable if out- planted colonies are able to rapidly contribute to the natural pool of larvae. 

When juveniles must tolerate harsh environments early in life, the disproportionate success of certain phenotypes across multiple early life stages will dramatically influence adult community composition and dynamics. In many species, large offspring have a higher tolerance for stressful environments than do smaller conspecifics (parental effects). However, we have a poor understanding of whether the benefits of increased parental investment carry over after juveniles escape harsh environments or progress to later life stages (latent effects). To investigate whether parental effects and latent effects interactively influence offspring success, we determined the degree to which latent effects of harsh abiotic conditions are mediated by offspring size in two stony coral species. Larvae of both species were sorted by size class and exposed to relatively high-temperature or low-salinity conditions. Survivorship was quantified for six days in these stressful environments, after which surviving larvae were placed in ambient conditions and evaluated for their ability to settle and metamorphose. We subsequently assessed long-term post-settlement survival of one species in its natural environment. Following existing theory, we expected that, within and between species, larger offspring would have a higher tolerance for harsh environmental conditions than smaller offspring. We found that large size did enhance offspring performance in each species. However, large offspring size within a species did not reduce the proportional, negative latent effects of harsh larval environments. Furthermore, the coral species that produces larger offspring was more, not less, prone to negative latent effects. We conclude that, within species, large offspring size does not increase resistance to latent effects. Comparing between species, we conclude that larger offspring size does not inherently confer greater robustness, and we instead propose that other life history characteristics such as larval duration better predict the tolerance of offspring to harsh and variable abiotic conditions. Additionally, when considering how stressful environments influence offspring performance, studies that only evaluate direct effects may miss crucial downstream (latent) effects on juveniles that have significant consequences for long-term population dynamics.

Coral bleaching occurs when corals expel their symbiotic algae, called zooxanthellae, or when zooxanthellae expel their photosynthetic pigments during times of high environmental stress. The exact reason why corals bleach has not yet been determined, but it is theorized that a combination of multiple environmental stress factors is the cause. It is also possible that coral bleaching serves as an adaptive mechanism by allowing different types of zooxanthellae, which may be more stress-resistant than the original zooxanthellae, to colonize the coral. Temperature, salinity, over-sedimentation, anoxia, presence of pollutants, and high amounts of UV irradiation are all factors thought to contribute to bleaching. Extensive coral bleaching research has been conducted since the mass bleaching event of 1998, but there is no data on the frequency of coral bleaching on Bonaire, Netherlands Antilles. This paper proposes a monitoring program that may be implemented to collect coral bleaching and recovery data on Bonaire’s reefs.

This student research was retrieved from Physis: Journal of Marine Science I (Fall 2006)19: 45-48 from CIEE Bonaire.

Located below the hurricane belt in the Netherlands Antilles, the island of Bonaire is rarely affected by major storms and high-wave action. In a rare storm event in November 1999, waves generated by hurricane Lenny hit the leeward side of Bonaire causing significant damage to many of the shallow reefs. Shallow reef sites (5-10m) were significantly more damaged than sites at deeper depths (20m) and there was evidence of toppling, sedimentation, and smothering. Little is known about the patterns of successional recovery of corals following hurricane damage in the Caribbean. This study investigated reef rugosity and coral species composition at sites that were damaged by hurricane Lenny versus those that were undisturbed. More than 8 years after hurricane Lenny there was a significant difference in species composition at disturbed and undisturbed sites and a significantly higher rugosity index at undisturbed sites. The recovery success of coral reefs is affected not only by past disturbances, but also by present and future disturbances, both chronic and acute. Storm damage caused by hurricane Lenny may have affected the overall resilience of the reef to anthropological disturbances such as increased eutrophication and sedimentation as well as natural disturbances including global climate change.

This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 43-47 from CIEE Bonaire.

Coral reefs are one of the most diverse ecosystems found on earth, and are home to many habitat-specific fish. The Gobiidae family is known to be one of the most habitat-specific groups. Two common gobies found in the Caribbean are Coryphopterus lipernes and Gobiosoma evelynae, and both species rest on live coral heads. This study was conducted to determine if C. lipernes and G. evelynae show a preference for certain coral species and if the presence of disease affects this selection. A benthic survey was performed using video transects and CPC data analysis, allowing calculation of percent frequency for each coral species and frequency of diseased corals. Goby searches were conducted using SCUBA within a depth range of 10 - 15 m along the reef, recording the coral of choice and its disease status. The results showed that C. lipernes selected for 3 coral species and against 5, favoring Colpophyllia natans and Montastraea cavernosa. G. evelynae selected for 3 coral species and against 5, favoring M. cavernosa and Stephanocoenia spp. Both goby species selected significantly against coral disease, C. lipernes had a mean disease selection ratio of 0.39, and G. evelynae showed a complete selection against disease. Coral reefs are important ecosystems that are currently under significant abiotic and biotic stressors. It is important to understand the influence that an increase in disease and reduction in coral abundance may have on habitat-specific fish.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 96-102 from CIEE Bonaire.

Globally, scleractinian coral populations are declining, and to fully understand this decline it is important to study potential coral stressors in-situ. One particularly interesting means of studying stressor effects is fluorescence in corals. Till now fluorescence research has focused primarily on laboratory studies. These experiments cannot fully account for real world effects of stressors such as disease, predation or competition on corals fluorescent patterns in nature. The purpose of this study was to develop a means of in-situ observation to study how coral are using fluorescent proteins in nature. Five sample organisms were used for each of the three categories of stress, and one group of healthy corals were used as control, UV photographs of each were then taken on a weekly basis. Visual trends across the photographs were analyzed for gradients in both red and green fluorescence using Photoshop. From this we detected patterns on predated and competing corals as well as significant gradients in both diseased and healthy corals. Healthy coral results indicated issues in light dispersal across coral colonies necessitating a reworking of the methodology for clearer results. However the presence of discernable trend lines across all other categories supports that this methodology could still be effective for future monitoring efforts. RFP and GFP associated proteins are good candidates for indicating the health of threatened coral reefs due to their ease of use and associations with important coral functions making the methodology discussed here significant in allowing their use.

This student research was retrieved from Physis: Journal of Marine Science XIX (Spring 2016)19: 64-73 from CIEE Bonaire.

Unusually warm ocean temperatures surrounding Bonaire during the late summer and fall of 2010 caused 10 to 20 % of corals to bleach (Fig. 1). Bleaching persisted long enough to kill about 10 % of the corals within six months of the event (Steneck, Phillips and Jekielek Chapters 2A – C). That mortality event resulted in the first significant decline in live coral at sites monitored since 1999 (Fig. 2). Live coral declined from a consistent average of 48 % (from 1999 to 2009) to 38 % in 2011 (Steneck Chapter 1). This increase in non-coral substrate increased the area algae can colonize and the area parrotfish must keep cropped short (Mumby and Steneck 2008). For there to be no change in seaweed abundance would require herbivorous fish biomass and population densities to increase, but they have been steadily declining in recent years. This decline in parrotfish continues despite the establishment of no-take areas (called Fish Protection Areas – FPAs) and the recent law that completely bans the harvesting of parrotfish. The other major herbivore throughout the Caribbean is the black spined sea urchin, Diadema antillarum. However, since 2005 Diadema abundance has steadily declined. Damselfishes continue to increase in abundance (except in FPAs) and their aggressive territoriality reduces herbivory where they are present. These declines in herbivory resulted in a marked increase in macroalgae (Steneck Chapter 1). Although patchily distributed, algae on some of Bonaire’s reefs are approaching the Caribbean average (Kramer 2003). All research to date indicates that coral health and recruitment declines directly with increases in algal abundance (e.g., Arnold et al 2010).
On the bright side, predatory fishes are increasing in abundance in general but increasing most strongly in FPAs. Typically, responses to closed areas take 3 - 5 years to begin to manifest themselves. Predators of damselfishes have increased significantly in FPA sites and there, damselfish abundances are trending downward. These trends are the first signs of changes in the FPAs, and they are encouraging.
Overall, Bonaire’s coral reefs today are more seriously threatened with collapse than at any time since monitoring began in 1999.
 
Monitoring Results
The abundance of live coral at the monitoring sites has been remarkably constant since 1999. However, the bleaching related mortality event (Fig. 1) resulted in the first marked decline in live coral.
Seaweed abundance (“macroalgae”) increased sharply in 2011. While the greatest increase in algae occurred at the 18th Palm site where effluent could have increased nutrient levels, most of the other sites showed marked increases in algal abundance (see Steneck Chapter 1). Coralline algae, which has been shown to facilitate coral recruitment, remains at or near unprecedentedly low levels (Fig 2). Herbivory from parrotfishes and the grazing sea urchin Diadema antillarum remains at or near the lowest levels recorded since monitoring began in 1999 (Fig. 3 and see Cleaver Chapter 5). Herbivory from parrotfish is widely thought to be most important (e.g., Steneck and Mumby 2008) but territorial damselfishes can negate parrotfishes’ positive effects by attacking grazing herbivores and preventing them from effectively grazing (Arnold et al 2010). Damselfish abundances have trended upward in recent years (Fig. 3). However, there is a hint of a reversal to this trend in the FPAs (see Arnold Chapter 3). This reversal is consistent with the possibility that areas without fishing have elevated abundances of damselfish predators such as species of groupers and snappers (Randall 1965)  
Predatory fishes including snappers, groupers, barracuda, grunts and others increased in abundance at our monitored sites (Fig. 4 and see DeBey Chapter 6a). Specific predators known to eat damselfishes (see Preziosi Chapter 6b) show variable population densities with only a hint of an increase in 2011.   
Predatory fishes increased in abundance in both biomass (most striking) and population densities (Fig. 5). While biomass of predators in FPA and control sites is identical, the population density of predators is slightly greater at FPA sites
Coral recruitment remained lower than recorded in 2003 and 2005 (Fig. 6). However, the abundance of juvenile corals was higher in 2011 than was quantified in 2009

Bonaire’s reefs remain among the best in the Caribbean. However, our monitoring has revealed some potentially troubling trends that may require management action. In 2005, we reported to the Bonaire Marine National Park on the status of Bonaire’s coral reefs, and we suggested a strategy for monitoring trends among four key reef attributes we believe track the health and resilience of Bonaire’s reefs (Steneck and McClanahan 2005). Here we report the results of monitoring studies conducted 2003, 2005 and now 2007 at each site. Where appropriate, we drew from Bonaire’s first AGRRA assessment conducted in February 1999 (Kramer and Bischof 2003) to extend temporal trends over a period of eight years. 
Troubling trends
We see three troubling trends of increased macroalgae, declining herbivory from parrotfish, and increases in damselfish populations. Of these, the first two are most serious (see Chapters 1, 2 and 3). Secondary trends of concern, increases in damselfish populations (Chapter 4) and declines in coralline algae (Chapter 1), could lead to reduced recruitment of reef corals (Chapter 7), but to date this is not evident (Chapter 7). Importantly, coral cover remains relatively high (Chapter 1). The monitored group of carnivorous fishes, the lutjanid snappers, are holding constant but we remain concerned about the past (Steneck and McClanahan 2003) and continued loss of other larger bodied reef carnivores such as groupers and barracuda. The positive ecological role of parrotfish is well documented (e.g. Mumby et al. 2006) so their decline is troubling. It is unclear exactly why their population densities are declining. While parrotfish are not currently a widely sought group of reef fish (Chapter 8), fishing pressure on them is growing. It is possible they are vulnerable to even modest fishing pressure, particularly from fish traps. Accordingly, we recommend that the capture and killing of parrotfish be stopped because of their key ecological role on Bonaire’s coral reefs. Further, other groups of grazing herbivores such as the longspined sea urchin (Diadema antillarum) are increasing but too slowly to effectively replace the functional role of parrotfish (Chapter 1). We suggest continued monitoring of key drivers of reef health (coral cover, algal abundance, herbivory and coral recruitment). Some standard protocols such as the Atlantic and Gulf Rapid Reef Assessment (AGRRA) are entirely commensurable with the data presented in our reports in 2003, 2005 and 2007 (this report). A streamlined monitoring protocol is likely to be most useful to managers to alert them as a potential problem is growing and, perhaps more importantly, to show improvement when it occurs.
 
 

Brief description of the recently started (Feb 2015) coral reef monitoring program in St. Eustatius using the guidelines agreed upon by the Caribbean (Global) Coral Reef Monitoring Network (Caribbean – GCRMN).