UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Spirobranchus giganteus Pallas 1766 is an obligate associate of coral. This study focused on the distribution of five branchial crown colormorphs (Blue, Brown, Marigold, Purple, and White) on eight coral species (Acropora I, Acropora II, Porites I, Porites II, Porites III, Porites IV, Porites V, Porites VI) by quadrat sampling method. White was the most abundant colormorph, representing 24.0% of the total. Blue was the least abundant colormorph at 9.5% of the total. There were no significant differences in Shannon-Weiner Diversity Index (H’) of colormorphs between coral species. Also, relative colormorph abundance did not differ significantly between coral species or between the Front and Back positions. Only Blue and Marigold differed significantly in relative abundance between Top, Midde, and Bottom positions. Findings support a colormorph distribution of colormorphs. There are two possible explanations: 1) mortality and selection effects on distribution and 2) phenotypic plasticity, a combination of genetic and environmental factors contributing to the occurrence of certain phenotypes.

The effects of human activities on the earth’s environment have gained increasing attention in recent years. With coral reefs declining worldwide, efficient tools for assessing reef health are more important than ever. The species of larger foraminifera known as Peneroplis pertusus share key characteristics with reef building corals. By examining the populations’ natural distribution along with the abiotic factors affecting bleaching, a better understanding of reef systems as a whole is achieved. In this study, P. pertusus was collected from ten different sites on a fringing reef in Moorea, French Polynesia. Collected from coral rubble at one, two, and three meters depths, they were analyzed for abundance, size, and extent of bleaching. Light experiments were used in the laboratory to determine response to increased solar radiation. One-way statistical analysis, along with the Wilcoxon test found no strong correlation between depth and percent bleaching. A difference between individual size and percent bleaching was found and a natural population dynamics are presumed to occur n Moorea. Light experiments found increased bleaching in P. pertusus showing increased solar radiation to be a factor in bleaching.

French Polynesia’s indigenous tamanu Tree (Calophyllum inophyllum) is an important natural resource harvested for lumber, resin, and oil. Being a marine-seed dispersed species it self-propagates and can be found growing along the coastline of Moorea. Development and harvest patterns on Moorea may be slowing the natural reproductive rate of the species. Fifty years ago it was recommended as a species to include in management programs as it had been noted to be in decline due to its slow growth and high use rates. Interviews with elders, carvers and healers indicated that the range has indeed diminished. A total island survey was performed and the resulting map of C. Inophyllum’s distribution indicates that the range is healthy- but it will continue to compete with human development for the diminishing resource of coastal terrain.

This study focuses on the current distribution and habitat preferences of the sedge Kyllinga nemoralis. It is a weed on Mo'orea but an invasive to other islands of hte Pacific. Annual precipitation, temperature, water availability, soil moisture, soil type, canopy cover and elevation are shown to influence the distribution of this species. A minor transplant study affirms its preference of full sun locations to those with low light due to canopy cover.

Studies examining benthic macrofauna of estuaries are becoming more prevalent in the scientific community but none have yet been conducted on the island of Moorea, French Polynesia. The present field study surveyed four estuaries on the island: the Papeahi, Paopao, Urufara and Vaihana Rivers. Organisms were collected and abiotic factors (including sediment type, depth, temperature, water flow, salinity, pH and dissolved oxygen) were measured to find correlations between species diversity and species abundances and the physical conditions that surround them. Abundance of taxa varied considerably among estuaries. Correlations were found between diversity and temperature and between gastropod abundance and depth/salinity. Many correlations reported in previous studies were absent; however this is most likely due to low abundances, small sample sizes and time constraints.

Communities of photosynthetic prokaryotes are found around the world in a huge variety of locations, one of which is hypersaline mudflats. The estuary in Tamae, Mo’orea has been mostly filled in by a golf course and severely cut the population of microbial mats. Microbial mats in the Tamae mudflats in Mo’orea, French Polynesia were studied. Eight different morphologies were described and mapped. Additionally, their microhabitats described based on salinity, temperature, number of crab holes, and ground water depth and all but temperature saw certain significant differences. Transects were run from one end to another, and using the same environmental parameters, changes over the entire mudflat were observed. There were no trends with temperature. All of the other parameters exhibited trends and seem to have an influence over mat distribution, however there is not concrete evidence to support the claim that these are the factors that limit these microbial mat distributions. This ecosystem is very complex and it is probable that many more factors affect their distribution. If this habitat is to be conserved it will need to be studied more.

This study was conducted on Mo'orea, French Polynesia to investigate and record the impacts of ecotourism on two populations of himantura fai, pink whiprays or pink whiptail stingrays. Two sites were chosen each with varying impact to rays. Photographs and recordings were made and analyzed. Thirty eight individual rays were identified, 29 from one site and 8 from the other. Five kinds of scarring were described and compared between the two. It was found the more dense ray population was more injured and impacted and habituated to humans. The higher frequency of injury suggests a lower quality of life and indeed a negative impact from ecotourism. A mock mark and recapture study was done using the Lincoln-Peterson method. The population estimates were 30 and 8, suggesting the 29 and 9 rays identified are the entire populations. No rays were seed at both sites, which suggests site fidelity.

The terrestrial biota of the French Polynesian archipelago presents a unique opportunity for study due to a relatively poor understanding of its biology. Among the terrestrial invertebrates, the Apoidea are one of many taxa with incompletely documented biodiversity. This study investigated the diversity of the bees on the island of Mo'orea, part of the Society Islands in French Polynesia. Across a range of elevations, I collected 239 individual bees and observed the floral visits of an additional 266 bees. The visited floral species were recorded to assess apoid use of floral resources, and vegetation surveys of collection sites were conducted to assess the available floral community. A total of five genera of bees were found on Mo'orea, including two which are recorded for the first time in the Society Islands. This study suggests that introduced species, rather than native species, comprise the bee biota of Mo'orea, with the longest established species seemingly introduced at or around the time of colonization by early Polynesians. With the exception of the genera Lithurgus and Megachile, bee genera were found to rely predominantly on non-native floral resources. Floral visitation predilection by Mo'orean bees may prove to further the spread of introduced and invasive floral species.

Planktonic larvae of many marine organisms have been known to cycle in abundance according to lunar phases. It is unknown, however, if these cycles are caused by timed release of larvae by the adults in accordance with lunar cues or if predation pressure on the larvae varies across the lunar cycle. Larvae of some invertebrate taxa are capable of predator detection and avoidance, suggesting that predation on meroplankton is lower than dispersal models predict. This study tracked lunar cycling of decapod larvae from Oct. 6, 2008 to Nov. 13, 2008 in Moorea, French Polynesia. Predator avoidance capabilities of the larvae and relative predation pressure during each phase of the moon were also tested in a laboratory setting. Larval abundances on the reef were highest during the new moon period and lowest during quarter and full moons, suggesting predation does affect lunar abundance cycling. Decapod megalops stage larvae were found to be capable of predator avoidance but younger stage zoeas were not. Predation pressure was also found to correlate directly with light intensity. Results of this study suggest predation does affects larval population cycling, however it is possible that both predation and larval release timing play a role in shaping larval abundances and dispersal.

Abstract. Humans have continually interacted with and transformed their surroundings. Cordyline fruticosa Chevalier 1919, was among the many plants Polynesians brought with them as they voyaged from western Polynesia to eastern Polynesia. Polynesian culture is historically associated with C. fruticosa, which was centered around the ancient marae, or temples. The distribution of the large, sterile, green leaf variety was studied at marae and contemporary areas such as homes and businesses on Mo’orea, French Polynesia. I expected to find the sacred green variety around marae and the ornamental red varieties in contemporary locations. No C. fruticosa plants were found around marae sites. Contrary to predictions, the green variety of C. fruticosa was more prevalent at the contemporary sites than the red varieties. Local Tahitians were consulted on current attitudes towards and uses of C. fruticosa. These elders indicated that the sacred green variety continues to be utilized in religious, medicinal, and cultural ways, perhaps explaining its prevalence over red varieties.

Islands of the south pacific are fragile ecosystems, home to native land and sea birds that evolved in the absence of predators. On Mo’orea, French Polynesia the first humans arrived around 600 AD bringing with them invasive vertebrate predators. This study examines one of these predators on Mo’orea by observing swamp harrier (Circus approximans) habitat preference and behavior to determine if it has changed in comparison to its source population. Also it will examine their role in seabird predation on Mo’orea through a series of animal waste sample collections at high elevations. Since swamp harrier introduction in 1885 their habitat preference has not much changed from their Australian source population. The majority of its time and foraging is spent over low vegetation, though some expansion into other habitats has occurred since there are no other raptors on the island with which to compete. Feral cats (Felis catus) are also prevalent on the island and along with the swamp harriers are preying upon the native seabird populations on Mo’orea. Tahiti petrels (Pesudobulweria rostrata) and Audubon's shearwaters (Puffinus lherminieri) are being preferentially eaten by these predators over the invasive songbirds at high elevation. Feral cats appear to be the more significant predator of seabirds and without their control nesting seabird colonies may cease to exist on Mo’orea.

Parasites are ecologically significant organisms and must be understood to properly appreciate nearly any community. Parasitism is one of the most common (if not the most common) lifestyles, and parasites can influence species throughout a community. One group of parasites, the Eulimidae, is a large family of marine gastropods. Unfortunately, eulimids have not been thoroughly studied and host use behaviors have not been well characterized at the specific, or even generic levels. Therefore, this study seeks to describe host preference, host detection and tracking, and dependence on host access for two eulimid species, both sharing the macrohabitat environment. A series of experiments and a field survey showed that Peasistilifer nitidula was host specific, actively located hosts by chemical cues, reattached to hosts quickly, and required frequent access to the host for survival. Conversely, Melanella acicula had a preferred host but parasitized others as well, did not actively pursue hosts by chemical or visual detection methods, reattached infrequently in the short-term, and could survive longer isolated from the host. Using these aspects of host use to compare these co-existing species showed significantly different life histories, and suggests possible niche differentiation between a generalist and specialist species.

 The role of mutualisms among invasive species in facilitating invasions remains relatively unexplored. Yet such interactions have high potential to alter intact community composition and function due to their positive fitness effects on the species involved. The following study explores an interaction that evolved independently among naturalized hibiscus and invasive ants and Hemiptera that colonized the island of Mo’orea, French Polynesia centuries apart.  For this study, a geographic survey was conducted across 7 plots, which revealed the relationship to be present across a broad range of habitats. Manipulative field experiments were also ran in order to classify the association as a mutualism, parasitism or commensalism. These experiments quantified changes in abundances and behaviors of ants and Hemiptera in response to different availabilities of sugar resources to ants. Results from these field experiments support the hypothesis that the relationship is indeed a mutualism, where all players receive a net benefit from their association with one another. The resultant finding that this is a geographically widespread mutualism among invasive species contributes to the study of invasion meltdowns. The discovery of the success of this invader-invader mutualism in an intact ecosystem contributes to a growing body of research on the role of synergistic effects of multiple species invasions in invasion meltdowns.

The tropical sea urchin genus Diadema, is considered one of the most significant and abundant. Their population dynamics greatly influence the health of coral reefs. Diadema have anti-predator behavior and defenses that help them to maintain a stable population. I investigated the limited spatial vision in Diadema savignyi, by testing their directional orientation to a target representing a crevice space used to hide from predators. This is the fourth sea urchin echinoderm to demonstrate evidence of spatial vision, the first for the genus Diadema. Furthermore, my results demonstrate that D. savignyi use their spines to filter light to improve their spatial vision. D. savignyi which had their spines removed lost their spatial vision. However, in starting closer to the target, D. savignyi still oriented without spines, suggesting spatial vision is still possible. In a field and lab study on the emergence times of D. savignyi, I found that D.savignyi may use daylight levels as a cue in their nocturnal emergence, usedto avoid their diurnal predators. The pervious understanding that Diadema react and process light supports my evidence of the role of light in emergence. My results illustrate mechanisms for which D. savignyi specifically are able to avoid predators, but also suggest the presence of such mechanisms in other sea urchins. In understanding these mechanisms of defense, it is possible to better understand the maintenance of sea urchin populations and thus their role in coral reef ecosystems.

Suspension feeders are sessile marine organisms dependent on plankton and organic particles transported by the water column for food. This study focused on the distribution of four suspension feeders (Dendropoma maxima, Spirobranchus giganteus, Heteractis magnifica, and Tridacna maxima) in Mo’orea, French Polynesia based on current, suspended particle abundance, and substrate type. Both D. maxima and S. giganteus were more frequently present at the site with highest current flow and suspended particle abundance. The positive correlation between current and suspended particle, or food, abundance suggests that a stronger current transports more organic particles to a set location than a weaker current. In comparison, H. magnifica and T. maxima abundance and occurrence were not related to current. This is because they are less reliant than D. maxima and S. giganteus on the current for suspension feeding. In comparison, all four species studied showed substrate preference. The distribution of the suspension feeders studied showed varying dependence on current and substrate type. Since suspension feeders regulate primary production by consuming plankton, their distribution and abundance greatly affects marine food chains. Understanding coral reef food chains is vital for comprehending the niche suspension feeders’ fill in coral reef ecosystems.

Plant-insect symbiosis and succession are important components of tropical ecosystems for understanding natural history and biodiversity. There are not many studies of gall succession and gall life cycles in tropical environments, even though it is an important component of tropical ecology. A number of gall specimens onSyzygium malaccense were followed over time, sampled for insect communities, and tested for areas of fungal coverage to determine if they underwent successional development and caused leaf decay outside the gall boundaries. Different gall stages were classified over this time period and were found to contain different communities. Desiccation and decay were found to cause gall color change, and the decay was limited to the gall boundaries avoiding theS. malaccense leaf.Syzygium malaccense galls were thus found to model succession, and also present a unique symbiotic system amongst a diverse set of tropical organisms.

Crabs of the species Dardanus pedunculatus form a symbiotic relationship with Calliactis tricolor anemones on Moorea, French Polynesia. Crabs actively collect anemones for protection against octopus predation, while simultaneously giving the anemones a better habitat, defense against predators, and food as a result of the crab’s messy eating. In a laboratory setting, crabs will compete for anemones with larger crabs winning competitions. This paper examined crabs’ field collection patterns, and found that larger crabs collect more anemones, cover a greater percentage of their dorsal side with anemones, and carry a larger volume of anemones than smaller individuals. An experiment was designed to determine collection preference when unimpeded by field restrictions, and found that larger crabs show similar collection patterns as in the field, while smaller crabs cover a greater percentage of their dorsal side with anemones than in the field. This implies that abundance of anemones limits collection for this population, and that smaller crabs are being out-competed for anemones in the field. Additional behavioral experiments were designed to determine individual anemone preference patterns. Crabs show no preference for anemones they had been associated with in the field, but did show a significant preference for larger anemones. Gaining a better understanding of this symbiosis adds to the much-needed literature on the fragile coral reef ecosystem.

Defense mechanisms have been long recognized as an important factor in establishing the development of many organism life histories. As a result, many processes associated with ensuring survivability have been very well established in organisms that utilize defense mechanisms. How these defense mechanisms have shaped the evisceration and regenerative processes of sea cucumber Holothuria leucospilota still remain largely unstudied. In this study it is revealed that Holothuria leucospilota remain very consistent in their modes of evisceration, ejecting the same organs in every evisceration event. The consistency is compounded by the finding that approximately 28% of their body mass is eviscerated regardless of organism size. In terms of organ regeneration, the thickening of the mesentery tissues is apparent at Day 4 and regeneration of the digestive tract at Day 16. Sediment feeding also resumes at Day 16 along with the regeneration of the digestive tract. No regeneration of the left respiratory tree or gonads is observed within the 28-day study.