Thesis (M. Sc.)--University of Hong Kong, 2005.

In Palm Beach County, S. terebrans burrows into grounded roots and trunks of R. mangle causing collapse. This is contrary to previous studies suggesting this species burrows only into free-hanging roots. Nutrients and C. virginica cover may affect S. terebrans abundance and distribution. Surveys show burrowing significantly varies among sites, but not between free-hanging and grounded roots. Nutrients vary by site, but neither N nor P was correlated with burrowing. Nutrient treated roots showed no colonization pattern associated with N or P. Lignin varied among sites, but didn’t affect burrowing. Finally, C. virginica limited colonization in the portion of R. mangle tissue it covered. The location of C. virginica on the seaward/landward side was not predictive of burrowing. R. mangle height and leaves were not negatively affected by cover treatment or burrowing. Results highlight the need for additional research to determine the influence of environmental factors on this species interaction. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Mangrove forests are subjected to many environmental factors which influence species distribution, zonation patterns as well as succession. Important driving factors in these forests are salinity, water level fluctuations and available light. This study investigated the response of red mangrove (Rhizophora mucronata Lam.) seedlings to these factors in controlled laboratory experiments. Increase in salinity and prolonged inundation within estuaries are predicted impacts resulting from sea level rise due to climate change. The study investigated the effect of five salinity treatments (0, 8, 18, 35 and 45 ppt) with a semi-diurnal tidal cycle on seedling growth. In a separate experiment the effect of different inundation treatments: no inundation, 3, 6, 9 hour tidal cycles and continuous inundation (24 h) were investigated. Both morphological and physiological responses of R. mucronata seedlings were measured. There was a decrease in growth (plant height, biomass and leaf production) with increasing salinity. Seedlings in the seawater, hypersaline and no inundation treatments showed symptoms of stress, having increased leaf necrosis ("burn marks"). The highest growth occurred in the low salinity (8 ppt) treatment, but the highest photosynthetic performance and stomatal conductance occurred in the freshwater treatment (0 ppt). The typical response of stem elongation with increasing inundation was observed in the 24 hr inundation treatment. In the light and salinity combination study there were ten different treatments of five different light treatments (unshaded, 20 percent, 50 percent, 80 percent and 90 percent shade) combined with two salinity concentrations (18 and 35 ppt). In this study the seedling growth: plant height, biomass, leaf surface area and leaf production were higher in the moderate salinity (18 ppt) treatments compared to the seawater (35 ppt) treatments. Biomass in the 35 ppt experiment decreased with increasing shade as well as in the unshaded treatments. Photosynthetic performance and stomatal conductance were lower for the unshaded treatment in both 18 and 35 ppt salinity compared to all other treatments with the same salinity. This suggests that R. mucronata more shade than sun tolerant, but overall it can be concluded that the species has a broad tolerance range. The results may be relevant in mangrove rehabilitation and predicting responses to climate change. This is important as mangrove ecosystems may adapt to changing sea levels and in order to restore areas it will be necessary to choose the mangrove species which will grow best. The results may also help to increase the protection of existing mangrove habitats.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Thesis (Ph. D.)--University of California, Santa Cruz, 2003. / Typescript. Includes bibliographical references (leaves 177-180).

Sphaeroma terebrans, is an ecological engineer that can significantly modify the habitat of free-hanging aerial prop roots of Rhizophora mangle. The wood-boring isopod extensively burrows into red mangrove aerial prop roots for habitat and protection from desiccation and access to phytoplankton. However, the burrows created have major consequences on the mangrove habitat and aerial root inhabitants. It has been suggested that sessile species residing in aerial root communities can either encourage or discourage colonization by S. terebrans. Abiotic factors can affect the distribution and abundance of mangrove forest and are the same factors which determine the composition and abundance of organisms living on the roots. Surveys indicated that burrowing damage was found predominately in the first 20 cm of the root tip. Exploratory Structural Equation Modeling (SEM) was used to test multivariate hypothesized models looking at habitat relationships with S. terebrans in aerial root communities. Temperature and dissolved oxygen were shown to be important drivers in affecting submerged root length of aerial roots. Ultimately, the indirect effects between these parameters proved to be stronger in influencing the barnacle – isopod association, which causes direct negative effects on submerged root length. Colonial tunicates showed weak effects in masking aerial roots from the damaging barnacle – isopod association. Chlorophyll a was used as a proxy for phytoplankton biomass and proved to be less influential than habitat protection for S. terebrans. Results highlight the need for experimentation in addition to modeling in order to determine the mechanisms influencing aerial root community inhabitants and further effects on the habitat. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

The formation of novel ecosystems by non-native species poses management challenges that are both socially and ecologically complex. This complexity necessitates consideration of both ecological dynamics and social attitudes and perceptions. Red mangrove propagules were introduced to Moloka'i, Hawaii in 1902 to mitigate the effects of soil erosion and they have since spread along the coast and to adjacent islands creating novel habitat. Non-native mangroves in Hawai'i present a unique case study to examine diverse social attitudes and perceptions resulting from a long history of land cover transformations on the Hawaiian Islands, socio-cultural diversity of involved stakeholders, and the potential array of ecosystem services they may provide under changing land use and climatic conditions. Ecological dynamics were examined to (1) determine whether novel mangrove habitat affects zooplankton diversity and richness, (2) test the hypothesis that zooplankton community composition differs significantly among established mangrove and coastal non-mangrove habitat, and (3) assess other factors driving differences in zooplankton community assemblages. This study found no significant differences found between sites with and without mangroves in terms of richness, diversity, or community composition. However, lunar cycles and site dynamics, including fishpond structure, mangrove and open shoreline length, percentage of mangrove shoreline length, total percentage of carbon in mangrove leaves, and disturbance in the upstream watershed influenced zooplankton community composition. These findings suggest that non-native mangroves support community composition, richness, and diversity similar to non-mangrove areas, though some widespread taxa have lower abundances in mangrove habitat. My research suggests that in the face of declining fisheries, threatened reef habitat, and changing climate and ocean conditions, mangroves may provide zooplankton habitat in novel locations similar to that provided by native habitat, such that habitat availability for zooplankton is not hindered by non-native mangroves. To understand social dynamics 204 residents of Moloka'i, Hawaii were surveyed to evaluate: 1) attitudes and perceptions about this non-native species, 2) what factors influence these attitudes, and 3) how attitudes influence perceptions about management. A belief that mangroves should be removed, concern about threats to Moloka'i's coast, and not relying on mangroves for benefit were the primary drivers of negative attitudes towards non-native mangroves. Support for management actions was predicted by attitudes towards mangroves, perception and concern about threats to Moloka'i's coast, and experiences involving mangroves. I propose a framework for assessing and incorporating diverse perceptions and attitudes into decision-making around non-native species that have created novel ecosystems. An active management approach allowing mangroves to thrive in certain locations and to provide services such as habitat and crabbing access while in other locations limiting their extent to protect native bird habitat and cater for human needs, including safe beach and ocean access, may ultimately offer the greatest benefits to both the ecosystem and society. As environmental issues, such as species introductions, become increasingly complicated in the age of the Anthropocene, with intricate relationships made more difficult in the face of climate change, integrated research in socio-ecological systems may provide a comprehensive approach to better evaluate and understand our changing world.

As communities and managers become aware of the long-term impacts of mangrove loss, estimated at 1-2% per year, interest in sediment erosion and mangrove rehabilitation has increased substantially. In this thesis project I 1) examine erosion rates within coastal fringing Rhizophora mangle ecosystems following mangrove clearing and compare these rates to accretion rates in intact mangroves; and 2) investigate the abiotic factors influencing mangrove seedling survival and regeneration of naturally colonizing R. mangle, in historic mangrove habitat after anthropogenic clearing. Differences in erosion were compared between patches of open-coast intact and anthropogenically cleared R. mangle to quantify the sediment trapping function provided by mangroves and its loss following clearing over a 24 month period. Growth rates of mangrove seedlings in intact forest were compared to seedlings in cleared areas. Seedling growth indicators were measured on 100 seedlings at five sites (50 in the intact and 50 in the cleared areas). To examine the limiting factors on seedling growth rates, nutrient addition and wave protection treatments were applied to seedlings in three disturbed areas. Sites within intact mangroves had sediment accretion (M= +3.83 mm) while areas cleared of mangroves had sediment erosion (M= -7.30 mm). Seedling growth (height) over the 2 year study period significantly differed between intact mangrove (M = 15.6 cm) and cleared (M = 10.24 cm) areas. Seedling mortality from the cleared areas (31%) differed from the intact areas (13%). Average seedling growth (height) was: greater with both nutrient/wave (M = 18.4 cm) and nutrient (M = 17.65 cm) treatments compared to controls (M = 10.8 cm), which suggests that providing nutrients and/or wave protection result in growth outputs comparable to seedlings found in intact mangroves. This study may prove to be useful in identifying areas that are most vulnerable to erosion following mangrove removal and ideal location of restoration following mangrove removal. Areas cleared of mangroves can lead to intensified erosion in areas where fringing reefs are not continuous. When managers are determining areas to focus resources for restoration, focusing on areas with nutrient rich habitat may result in higher survival rates and growth outputs.

Sphaeroma terebrans (Bate 1866) is an economically and ecologically important cosmopolitan species because this isopod is found burrowed in wood and marine structures of fresh to saline water. Existing literature on S. terebrans focuses on the destruction of red mangrove (Rhizophora mangle) in India, Pakistan, and Florida. This study concentrates on S. terebrans habitat and boring preferences in bald cypress (Taxodium distichum) in Lake Pontchartrain near the Bonnet Carre Spillway, Louisiana. In addition laboratory experiments for water column distribution and substrate preferences were conducted using cypress, Styrofoam, and balsa. Results indicate that this population may be parthenogenic and that wood or material hardness determines whether S. terebrans burrow when given a choice of substrates. The lake shoreline near the Bonnet Carre Spillway is retreating and the presence of S. terebrans contributes to shoreline erosion by weakening and destroying cypress. This has implications for restoration projects in coastal Louisiana.

Many coastal plant species thrive across a range of environmental conditions, often displaying dramatic phenotypic variation in response to environmental variation. We characterized the response of the critical foundation species Rhizophora mangle L. to full factorial combinations of salt and nitrogen (N). We used seedlings collected from five populations and measured traits related to salt tolerance and N amendment. The response to increasing salt included significant plasticity in succulence, leaf mass area (LMA), and root to shoot ratio (R:S). Seedlings also showed overall reduced maximum photosynthetic rate in response to N amendment, but this response depended on the level of salt and varied by site of origin of the seedlings. Seedlings from different sites also differed in height growth, LMA, R:S, and total dry biomass. Generally, survival was lower in high salt and high N, but the impact varied among sites. Overall, this study revealed significant trait plasticity in response to salt and N level, and differentiation of responses of seedlings among different sites. Seedling survival depended on maternal family for 3 of 5 sites showing variation within and among sites. Variation in trait plasticity and seedling survival in R. mangle may be important for future adaptation to a complex mosaic of environmental conditions.