UCB Moorea Class: Biology and Geomorphology of Tropical Islands

Autotomy and regeneration are widespread in many groups of invertebrates and vertebrates, such as annelids, crustaceans, amphibians, and reptiles. Regeneration is common in all classes of Echinodermata and prevalent in ophiuroid brittle stars. Moorea, French Polynesia was surveyed for species of brittle stars living on coastal areas of the island in different habitats.

Ophiuroid populations were sampled in habitats such as a mangrove marsh, a sandy beach with coral rubble and a jetty with coral rubble and conglomerate coral to determine percentages with regenerating arms. Macrophiothix longipeda (Lamarck 1816) from the mangrove marsh and two populations of Ophiocoma scolopendrina (Lamarck 1816) from the beach and jetty were studied to determine if there were differences in experimental rates of arm regeneration after induced autotomization. Each habitat was colonized by distict ophiuriod assemblages and had different percentages of regenerating individuals; M. longipeda was found to be regenerating multiple arms simultaneously and had the highest rate of regeneration. Regeneration rates differed by species; mostly likely influenced by habitat, ecology and biology of each species.

Wood-decaying macrofungi are an important component of forest ecosystems because they are the major decomposers of dead woody debris and are crucial for nutrient cycling. This is especially true in the tropics where biomass is high. However, most studies to date have focused on temperate forests in the northern hemisphere. Little is known about wood-inhabiting fungi in French Polynesia. In fact, no identification materials exist. The following study seeks to fill this gap in knowledge. First, a general survey was done of the wood-fungi occurring in the mountains of Moorea. Next, in a pilot study, all Hibiscus tiliaceus dead wood (>1cm) was measured and surveyed for fungi using 10, 25-meter line transects. The aim of this phase was to determine if wood with fungi has different characteristics than wood without. Fungi were found on 61% of wood surveyed, but larger logs, and wood of intermediate decay were more likely to have at least one species. An additional 20 transects focused only on wood with fungi. A total of 114 species were found on 644 pieces of Hibiscus tiliaceus wood. However, 36.8% species were found only once and most wood had only 1 or 2 species. There were a few very abundant species, and the others were rare. When common species were examined individually, it was evident that many had preferences for certain wood sizes and decomposition. Species richness was found to positively correlate with average diameter, and wood of intermediate decay was also found to have greater species richness. In general, the results of this study were found to support much of the research conducted in temperate forests. Although the details differ, the underlying trends of diversity and succession are surprisingly similar.

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.

Environmental Science Policy and Management, University of California, Berkeley, California 94720 USA Abstract. Interspecific mutualisms between ant and scale insect species have been well documented as symbiotic relationships that merit resource acquisition in exchange for protection. In this study, insect removal experiments were preformed on the branches of Psidium guajava in order to measure the effects that insect populations have on one another. Five ant removal, five scale removal and five control trees were treated. Data was taken daily over the course of 18 days. Ant activity was measured using a one-minute, unidirectional, point count and the number of scales per branch was determined by photographing a sample of five leaves per branch. Wilcoxon rank-sum tests found that ant populations differ significantly to that of controls in the absence of scale insects. Scale insect populations were not significantly affected by the removal of ants. Observational ant behavior data was also collected that supports possible tending behavior.

Epiphytes are important in forest ecosystems because they contribute to species diversity and aid in nutrient cycling. Despite this, the ecology of tropical epiphytes, particularly nonvascular species, is not well understood. This study compared epiphyte richness, cover, diversity, and species distributions to host tree diameter, canopy cover, aspect, and height on the trunk. Thirty-two Metrosideros collina trees were sampled for epiphyte species every 0.5 centimeters along circumferential transects at 0, 0.75, and 1.5 meters off the ground. Host tree diameter at 0.5 meters was measured, as well as canopy cover at North, South, East, and West. Epiphyte cover was lowest at the bottom of the trunk and highest at 1.5 meters. Richness correlated positively with diameter and canopy cover, but it did not vary significantly with height or aspect, according to the Wilcoxon and Tukey tests. Epiphyte cover correlated positively with canopy cover, but it did not vary significantly with diameter or aspect. Moss and fern cover increased significantly with diameter but did not vary with height. Liverwort and lichen cover were not correlated with diameter, but they were lowest at the bottom of the trunk and highest at 1.5 meters. Diversity, calculated with the Shannon-Wiener index, correlated positively with epiphyte cover and tree diameter but did not vary significantly with height. Overall, epiphytes preferred habitats in the upper trunk region on trees with high canopy cover, and their distributions were correlated with every variable except aspect.

Ferns present an interesting case in island biogeography because of their unusually high dispersal ability. A general survey of the filmy ferns (Hymenophyllaceae) of Moorea, French Polynesia was undertaken by observing distribution in the field, conducting tests of desiccation tolerance, and inferring a phylogeny based on morphological characters. A total of 12 filmy fern species (including three species previously unreported in the literature for Moorea) were found to occur in moist, wellcovered habitats throughout the island, with distinct sets of high elevation and low elevation species. Five species were included in an experiment to determine relative degree of desiccation tolerance; results indicate that terrestrial species have lower desiccation tolerance than epiphytic or epipetric species. In order to place the Moorea filmy ferns in the larger archipelago context, eight additional Society Island species were included in the phylogeny for a total of 20 taxa based on 21 morphological characters; interspecies relationships reflect the taxonomy of Hymenophyllaceae sensu lato. Filmy fern species are widely dispersed throughout the Society Islands, and there is no indication of an adaptive radiation on Moorea.

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.

Organisms experience physiological and ecological changes during ontogenesis, and studies have shown that such changes have an impact on behavior over the life cycle. However, little is known about how octopus behavior changes during ontogeny. The pygmy octopus, Octopus bocki (Adam 1941), expresses differences in chromatophore development and mantle length between developmental stages. These changes may be important in predator defense, therefore I hypothesized that predator response behavior also changes over the life cycle. Timed interactions between an octopus and a fish predator were used to compare the behaviors and color displays exhibited by three different size categories of O. bocki; juvenile, sub-adult, and adult. Color display diversity was analyzed using the Shannon-Weiner diversity index. The analysis revealed a negative correlation between color display diversity and size during predator interactions, supporting the hypothesis that behavior changes over the life cycle. Counter-intuitively color display diversity decreases while chromatophore development increases. To broaden the context in which behavior was examined, interactions between adult O. bocki were used to investigate how adults use color displays. The number of color/texture combinations was graphed to compare displays expressed during predator interactions with those expressed during intraspecific interactions. A Wilcoxon test revealed that adult O. bocki used significantly more color and texture displays during intraspecific interactions than during predator interactions. I concluded that adult octopuses use color displays for communication rather than predator defense and that these displays change during ontogenesis.

The study of microorganisms and filamentous blue-green algae holds great ecological and geological importance; such microbial communities to be on of the first forms of life as well as the initial source of atmospheric oxygen. In Moorea, an island in the South Pacific, the microbial communities found on the intertidal mudflats have been widely studied and characterized. However, little is known about the marine mats that are consistently covered with seawater. This study surveyed the algal communities present in the shallow lagoon formed at Temae Beach, a public sand beach located on the northeast tip of Moorea. Seven morphologically different mats were observed and their distributions determined and mapped throughout two regions: the littoral (intertidal and sub-tidal) and back reef. The majority of mats were found within the sub-tidal while none were seen within the intertidal and very few observed within the back reef region. A common trend observed within this distribution found specific morphological types consistently located within the same general areas. Additional observations of fish herbivory as well as shear stress and current flow over these mats were also briefly investigation. Overall, while this study provides a brief characterization of what is found in the lagoon, further studies of these marine mats are needed to strengthen these initial findings and, in particular, to investigate specific factors attributing to why the mats disperse as they do.

While water striders (Hemiptera: Gerridae) have a global distribution different species have adapted to very different habitat types. Freshwater water striders such as Limnogonus luctuosus live in areas along streams and rivers with little to no flow. Marine water striders, such as coastal species Halobates hawaiiensis, have adapted to life on the surface of the ocean. Since these types of water striders live in such different habitats, and face different environmental factors their food preference and behavior can be quite different. In this study, average density of L. luctuosus individuals was measured along the Opunohu River. Also, food preference, behavior, and the effects of increased density were tested in the laboratory for both L. luctuosus and H. hawaiiensis. Response time and frequency of approach to mobile and immobile prey items were recorded for H. hawaiiensis and L. luctuosus. H. hawaiiensis preferred immobile prey while L. luctuosus preferred mobile prey. Frequency of several behaviors (i.e. movements, moving away from others, approached by others, approaching others, attacking, being attacked, jumping, and cleaning) were compared between species, and within species at increasing densities. There were differences between species in the frequency of movements, approaching others, being approached, jumping, and cleaning. Density affected movements, moving away from others, jumping, and cleaning for H. hawaiiensis. Density affected movements, moving away from others, and cleaning behaviors for L. luctuosus. The different ecology of these two species can be used to explain why differences exist in both food preference and frequencyof behaviors.