This paper is primarily a study of the factors contributing to the distribution of Tegula funebralis and Tegula brunnea in the vicinity of Bodega Bay, California. The two species seldom appear extensively together in the same zone. Tegula brunnea is found on the exposed outer coast of Tomales Point, but not in the immediate zone of Tegula funebralis. Tegula funebralis is found at some points north of Dillon Beach, but it is rarely in the presence of abundant Tegula brunnea. The writer hopes that his efforts may lay a basis for more ecological studies of this genera on the Pacific Coast.

Thompson (1967) defines three developmental types for Opisthobranchia with representative nudibranchs in each category. The types are: 1.) planktotrophic larvae which are obligatory plankton feeders prior to progressive metamorphosis, 2.) lecithotrophic larvae which may feed on the plankton, but do not need to do so in order to metamorphose, 3.) direct development which results in hatching of a post veliger, benthic juvenile. Tardy (1970) feels that Thompson's Type 3 development is artificial. Thus, he incorporates direct development into the lecithotrophic developmental type. Tardy then proposes a classification of metamorphic types based on larval shell type (Thompson, 1961) and on larval feeding behavior (ie. lecithotrophic vs. planktotrophic larvae). I agree with Thompson's (1967) distinction between direct and lecithotrophic developmental types in the sense that they represent ecologically diverse ontogenies. The major explicit assumption in the above definition of planktotrophic larvae is that feeding is a necessary prerequisite to progressive metamorphosis. However, both Thompson (1967) and Tardy (1970) appropriately note that metamorphic observations of planktotrophic larvae are fragmentary and circumstantial. Thus, the definition of planktotrophic larvae rests its credibility on larval morphology at hatching, and the implicit assumption that energy is required (ie. feeding) to develop the organs necessary to accommodate the functional transition to the adult mode of life. The present study describes the early embryology, larval development, veliger morphology and feeding behavior of Hermissenda crassicornis and Aeolidia papillosa. Veligers of the facelinid, Hermissenda crassicornis and the aeolid, Aeolidia papillosa have striated, Type 1 (coiled) larval shells and fall within Thompson's (1967) definition of planktotrophic larvae. Veligers of both species remain planktonic for two to five days after hatching. They subsequently become epibenthic swimmers and discard their larval shells. There is considerable variation in the amount of yolk reserves in the gut and diverticulae of recently hatched veligers. An individual egg mass yields larvae with and without yolk reserves. The results show that shell length frequency of hatching larvae is distributed bimodally. There is a larval dimorphism based on shell length at hatching, the presence of yolk reserves and feeding ability. Feeding larvae are found to differ with respect to diet; the difference being associated with shell length of the larvae in relation to food particle size. The results are discussed in a comparative review of larval development in the Eolidoidea. Secondly, the relative dependency of nudibranch larvae on feeding ability is discussed with respect to the morphological and developmental categorization of opisthobranch metamorphic responses. The functional and ecological considerations of feeding in gastropod and selected invertebrate larvae are discussed with respect to the evolution of larval strategy and life cycle phenomena.

No description available.

A comparative study of the field populations of Crepidula lingulata, Crepidula nurnmaria, and Calyptraea fastigiata indicated all three preferred a rocky substrate but favored different size rocks. Their positions on the rocks varied but the greatest numbers were found attached to the undersides. Crepidula lingulata and C. nummaria preferred larger rocks and were found in intraspecific associations more often than C. fastigiata which preferred smaller rocks. These associations occurred with a 1:1 sex ratio; however, the overall population did not. Crepidula lingulata had a high female count and C. fastigiata a high male count. Males, of all three species, were smaller in size than females. Leptasterias hexactis and Evasterias troschellii were found to be possible predators. Protection was afforded those attached to the undersides of rocks. All three species used the radula to remove irritants from under the shell including the tube feet of attacking sea stars.

The deep ocean holds a diversity of life that remains to be discovered and described. Marine ecosystems fueled by chemosynthesis, such as hydrothermal vents and hydrocarbon seeps, represent biodiversity hotspots along the ocean floor. Yet, investigations into the diversity, genetic connectivity, and biogeography of life at such ecosystems are still ongoing. The present dissertation explores the diversity and biogeography of deep-sea gastropod mollusks from hydrocarbon seeps at the Pacific Costa Rica Margin to understand what factors lead to the generation and maintenance of novel biodiversity at chemosynthesis-based ecosystems in the ocean. The Pacific Costa Rica Margin was extensively sampled and explored between 2017 and 2019 and yielded an abundance and diversity of marine life. Gastropod mollusks were chosen as the model organisms for this research as they are taxonomically diverse, are found in high abundance, and occur at chemosynthesis-based ecosystems worldwide. Integrating taxonomic, phylogenetic, population genetic, and biogeographic methods, this dissertation contributes new species, occurrence records, genetic data, taxonomic tools, and biogeographic knowledge for deep-sea gastropods. As global biodiversity continues to be threatened by anthropogenic impacts such as overexploitation and climate change, documenting and understanding deep-sea biodiversity and the factors that influence it is of critical importance. / Biology

Choi Mei Mei. / Thesis submitted in: December 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 214-236). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.vi / Table of Contents --- p.viii / List of Tables --- p.xi / List of Figures --- p.xii / Chapter Chapter One: --- General Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Coral bleaching --- p.2 / Chapter 1.1.2 --- Predation of corals by corallivorous gastropods --- p.20 / Chapter 1.2 --- Introduction of Study Sites- Tung Ping Chau --- p.33 / Chapter 1.3 --- Objectives of the Study --- p.35 / Chapter 1.4 --- Structure of this Thesis --- p.36 / Chapter Chapter Two: --- "Coral Bleaching and Predation by Corallivorous Gastropods in the Coral Communities of A Ye Wan and A Ma Wan, Tung Ping Chau" --- p.40 / Chapter 2.1 --- Introduction --- p.40 / Chapter 2.2 --- Materials and Methods --- p.45 / Chapter 2.2.1 --- Quantitative surveys --- p.45 / Chapter 2.2.2 --- "Quantifying the colour of corals, Porites lobata, in Tung Ping Chau" --- p.47 / Chapter 2.2.3 --- Physical parameters --- p.49 / Chapter 2.2.4 --- Data and statistical analysis --- p.49 / Chapter 2.3 --- Results --- p.50 / Chapter 2.3.1 --- Live coral coverage in A Ye Wan and A Ma Wan --- p.50 / Chapter 2.3.2 --- Proportion of Porites lobata paled --- p.52 / Chapter 2.3.3 --- Changes in colour intensity of Porites lobata between seasons --- p.54 / Chapter 2.3.4 --- Density of corallivorous gastropods --- p.55 / Chapter 2.3.5 --- Percentage coverage of live and dead Acropora tumida --- p.55 / Chapter 2.3.6 --- Physical parameters --- p.57 / Chapter 2.4 --- Discussion --- p.59 / Chapter 2.4.1 --- Live coral cover in A Ye Wan and A Ma Wan --- p.59 / Chapter 2.4.2 --- Bleaching of Porites lobata in summer and winter --- p.61 / Chapter 2.4.3 --- Colour intensity of Porites lobata in different seasons --- p.67 / Chapter 2.4.4 --- Predation on corals by corallivorous gastropods --- p.69 / Chapter Chapter Three: --- "Study on Coral Bleaching, Pontes bbata, in Tung Ping Chau by using Permanent Quadrats" --- p.103 / Chapter 3.1 --- Introduction --- p.103 / Chapter 3.2 --- Materials and Methods --- p.104 / Chapter 3.2.1 --- Study sites --- p.104 / Chapter 3.2.2 --- Permanent quadrat monitoring --- p.105 / Chapter 3.2.3 --- Corals sampling for zooxanthellae density and chlorophyll a concentration analysis --- p.106 / Chapter 3.2.3.1 --- Tissus collection --- p.106 / Chapter 3.2.3.2 --- Zooxanthellae counting --- p.107 / Chapter 3.2.3.3 --- Chlorophyll a determination --- p.107 / Chapter 3.2.3.4 --- Determination of coral surface area --- p.108 / Chapter 3.2.4 --- Data analysis --- p.108 / Chapter 3.3 --- Results --- p.109 / Chapter 3.3.1 --- Monitoring of bleaching of porties lobata in permanent quadrat --- p.109 / Chapter 3.3.2 --- Density of Zooxanthellae in Porites lobata --- p.111 / Chapter 3.3.3 --- Concentration of Chlorophyll a in Porites lobata --- p.112 / Chapter 3.3.4 --- Chlorophyll a per zooxanthellae --- p.113 / Chapter 3.4 --- Discussion --- p.114 / Chapter Chapter Four --- Study of Predation on coral Acropora tumida by Corallivorous Gastropods in Tung Ping Chau --- p.138 / Chapter 4.1 --- General Introduction --- p.138 / Chapter 4.2 --- Materials and Methods --- p.140 / Chapter 4.2.1 --- Study sites --- p.140 / Chapter 4.2.2 --- Preliminary evaluation of corallivorous gastropods as the coal predator --- p.141 / Chapter 4.2.3 --- Monthly monitoring of permanent quadrat --- p.142 / Chapter 4.2.4 --- Data and statistical analysis --- p.144 / Chapter 4.3 --- Results --- p.145 / Chapter 4.3.1 --- Species of corallivorous gastropods in Tung Ping Chau --- p.145 / Chapter 4.3.2 --- Feeding behavior of corallivorous gastropods in Tung Ping Chau --- p.146 / Chapter 4.3.3 --- Density of corallivorous gastropods --- p.147 / Chapter 4.3.3.1 --- Monthly change in density of corallivorous gastropods --- p.147 / Chapter 4.3.3.2 --- Correlation between gastropod density and temperature --- p.149 / Chapter 4.3.4 --- Cumulative percentage of area of feeding scar over time --- p.149 / Chapter 4.3.5 --- Monthly percentage change in the areas of feeding scar --- p.152 / Chapter 4.3.5.1 --- Monthly percentage change in the areas of feedling scar due to predation by Cronia margariticola and Drupella rugosa --- p.152 / Chapter 4.3.5.2 --- Correlation between gastropod density and monthly percentage change in area of scar --- p.153 / Chapter 4.3.5.3 --- Correlation between temperature and monthly percentage in area of the feeding scar --- p.154 / Chapter 4.3.6 --- Rate of predation --- p.154 / Chapter 4.3.6.1 --- Rate of predation by the corallivorous gastropods --- p.154 / Chapter 4.3.6.2 --- "Correlation between rate of predation, gastropod density and seawater temperature" --- p.155 / Chapter 4.3.7 --- Population size structure of the corallivorous gastropods --- p.156 / Chapter 4.3.7.1 --- Population size structure of Cronia margariticola --- p.156 / Chapter 4.3.7.2 --- Population size structure of Drupella rugosa --- p.158 / Chapter 4.4 --- Discussion --- p.159 / Chapter 4.4.1 --- Feeding behaviours of corallivorous gastropods --- p.159 / Chapter 4.4.2 --- Density of corallivorous gastropods --- p.162 / Chapter 4.4.3 --- Cumulative percentage of area of feeding scar --- p.170 / Chapter 4.4.4 --- Monthly percentage change of area of feeding scar --- p.173 / Chapter 4.4.5 --- Rate of predation --- p.175 / Chapter 4.4.6 --- Size structure of population size --- p.178 / Chapter 4.4.7 --- Predatory pressure from corallivorous gastropods in Tung Ping Chau --- p.185 / Chapter Chapter Five --- Summary and Perspectives --- p.207 / References --- p.214

Die vorliegende Arbeit wurde als kumulative Dissertation auf der Grundlage von in international anerkannten Zeitschriften mit Fachgutachtersystem (Peer-review-Verfahren) veröffentlichten Publikationen verfasst. Mit Hilfe eines neuen integrativen Ansatzes aus Morphologie und Molekulargenetik wurden Studien zur intraspezifischen Variabilität einzelner Vertreter der Familie Lymnaeidae (Schlammschnecken) durchgeführt, die Schlussfolgerungen darüber zulassen, welche Wertigkeit den in dieser Gruppe bisher für Taxonomie und Systematik verwendeten morphologischen und anatomischen Merkmalen überhaupt zugemessen werden sollte. Ein weiteres Ziel der Analysen war herauszufinden, inwiefern eigene Rekonstruktionen phylogenetischer Bäume, basierend auf Kern- und Mitochondrienmarkern, bisher bestehende Hypothesen zur Taxonomie und Systematik der Lymnaeidae bestätigen oder widerlegen. Erste eigene molekulargenetisch überprüfte morphologische Analysen bei paläarktischen Vertretern der Gattung Radix zeigen, dass die zur Artdifferenzierung etablierten Merkmale Gehäuseform, Mantelpigmentierung, Längenverhältnis der beiden Abschnitte des männlichen Kopulationsapparates (Praeputium und Phallotheca), Länge des Bursaductes und Form der Bursa copulatrix eine höhere innerartliche Variabilität aufweisen als eigentlich für die einzelnen Arten angenommen wurde. Sie sind, entgegen bisheriger Annahmen, zu einem großen Teil nicht artspezifisch. Molekulargenetisch deutlich unterscheidbare Arten können die gleiche Gehäuseform und Mantelpigmentierung aufweisen und sind oft auch mittels anatomischer Merkmale nicht eindeutig unterscheidbar. Es kann, auch anhand erster eigener Studien an anderen Vertretern der Familie Lymnaeidae, geschlussfolgert werden, dass von den meisten Malakologen bisher in diese Merkmale innerhalb der Schlammschnecken eine Bedeutung für Taxonomie und Systematik hineininterpretiert wurde, die sie offensichtlich auf Grund ihrer hohen Plastizität nicht besitzen. Die molekulargenetischen Methoden eröffnen hier neue Perspektiven für ihre Beurteilung sowie für die objektivere Abgrenzung von Arten und Gattungen. Auf der Basis der neuen Erkenntnisse über die Variabilität morphologischer Merkmale wurde für die mitteleuropäischen Vertreter der Gattung Radix ein neuer Bestimmungsschlüssel erarbeitet, der mehr Radix-Formen als bisher berücksichtigt. Bei molekulargenetischen Untersuchungen an Vertretern der Gattung Stagnicola konnte ein relativ hoher Prozentsatz an Hybridisierung festgestellt werden, was in der Praxis Konsequenzen für die Anwendung des Barcoding mit mitochondrialen Markern (COI und Cytochrom b) hat. / This work was written as cumulative doctoral thesis based on publications in peer reviewed international journals. Aim of the studies was to analyse the range of the intraspecific variability of some representatives of the family Lymnaeidae as well as to find out which value should be given to the morphological and anatomical characters used for taxonomy and systematics at all. For this a new integrative approach of morphology and molecular genetics was sought. It was also important to find out how own reconstructions of phylogenetic trees based on nuclear and mitochondrial markers confirm or refute existing views on taxonomy and systematics of the Lymnaeidae. First own morphological analyses of Palaearctic representatives of the genus Radix checked by molecular genetics reveal that shell morphology, mantle pigmentation, length ratio of Praeputium to penial sheath, length of the duct of the bursa copulatrix and shape of the bursa show more variability in this characteristics as recognised for these species in literature. They are, contrary to previous assumptions, to a large extent not specific for single species. With molecular genetic methods clearly distinguishable species may have the same shell morphology and mantle pigmentation and could be not clearly differentiated by anatomical characters in many cases. It can be concluded, also on the basis of own studies of other representatives of the family Lymnaeidae, that to these characters was given an importance for taxonomy and systematics by most of the malacologists that they obviously do not have because of their high plasticity. Molecular genetic methods allow a new interpretation of the importance of morphological and anatomical characters and a more objective definition of species and genera. Based on the new findings on variability of morphological characters a new determination key for the representatives of the genus Radix in central Europe was elaborated. It enables the determination of more Radix forms than it was previously possible with determination tools. Molecular genetic analyses of representatives of the genus Stagnicola revealed a high percentage of hybridisation. In practise, this has consequences for the application of barcoding on the base of mitochondrial markers (COI and cyt-b).

Die vorliegende Arbeit wurde als kumulative Dissertation auf der Grundlage von in international anerkannten Zeitschriften mit Fachgutachtersystem (Peer-review-Verfahren) veröffentlichten Publikationen verfasst. Mit Hilfe eines neuen integrativen Ansatzes aus Morphologie und Molekulargenetik wurden Studien zur intraspezifischen Variabilität einzelner Vertreter der Familie Lymnaeidae (Schlammschnecken) durchgeführt, die Schlussfolgerungen darüber zulassen, welche Wertigkeit den in dieser Gruppe bisher für Taxonomie und Systematik verwendeten morphologischen und anatomischen Merkmalen überhaupt zugemessen werden sollte. Ein weiteres Ziel der Analysen war herauszufinden, inwiefern eigene Rekonstruktionen phylogenetischer Bäume, basierend auf Kern- und Mitochondrienmarkern, bisher bestehende Hypothesen zur Taxonomie und Systematik der Lymnaeidae bestätigen oder widerlegen. Erste eigene molekulargenetisch überprüfte morphologische Analysen bei paläarktischen Vertretern der Gattung Radix zeigen, dass die zur Artdifferenzierung etablierten Merkmale Gehäuseform, Mantelpigmentierung, Längenverhältnis der beiden Abschnitte des männlichen Kopulationsapparates (Praeputium und Phallotheca), Länge des Bursaductes und Form der Bursa copulatrix eine höhere innerartliche Variabilität aufweisen als eigentlich für die einzelnen Arten angenommen wurde. Sie sind, entgegen bisheriger Annahmen, zu einem großen Teil nicht artspezifisch. Molekulargenetisch deutlich unterscheidbare Arten können die gleiche Gehäuseform und Mantelpigmentierung aufweisen und sind oft auch mittels anatomischer Merkmale nicht eindeutig unterscheidbar. Es kann, auch anhand erster eigener Studien an anderen Vertretern der Familie Lymnaeidae, geschlussfolgert werden, dass von den meisten Malakologen bisher in diese Merkmale innerhalb der Schlammschnecken eine Bedeutung für Taxonomie und Systematik hineininterpretiert wurde, die sie offensichtlich auf Grund ihrer hohen Plastizität nicht besitzen. Die molekulargenetischen Methoden eröffnen hier neue Perspektiven für ihre Beurteilung sowie für die objektivere Abgrenzung von Arten und Gattungen. Auf der Basis der neuen Erkenntnisse über die Variabilität morphologischer Merkmale wurde für die mitteleuropäischen Vertreter der Gattung Radix ein neuer Bestimmungsschlüssel erarbeitet, der mehr Radix-Formen als bisher berücksichtigt. Bei molekulargenetischen Untersuchungen an Vertretern der Gattung Stagnicola konnte ein relativ hoher Prozentsatz an Hybridisierung festgestellt werden, was in der Praxis Konsequenzen für die Anwendung des Barcoding mit mitochondrialen Markern (COI und Cytochrom b) hat. / This work was written as cumulative doctoral thesis based on publications in peer reviewed international journals. Aim of the studies was to analyse the range of the intraspecific variability of some representatives of the family Lymnaeidae as well as to find out which value should be given to the morphological and anatomical characters used for taxonomy and systematics at all. For this a new integrative approach of morphology and molecular genetics was sought. It was also important to find out how own reconstructions of phylogenetic trees based on nuclear and mitochondrial markers confirm or refute existing views on taxonomy and systematics of the Lymnaeidae. First own morphological analyses of Palaearctic representatives of the genus Radix checked by molecular genetics reveal that shell morphology, mantle pigmentation, length ratio of Praeputium to penial sheath, length of the duct of the bursa copulatrix and shape of the bursa show more variability in this characteristics as recognised for these species in literature. They are, contrary to previous assumptions, to a large extent not specific for single species. With molecular genetic methods clearly distinguishable species may have the same shell morphology and mantle pigmentation and could be not clearly differentiated by anatomical characters in many cases. It can be concluded, also on the basis of own studies of other representatives of the family Lymnaeidae, that to these characters was given an importance for taxonomy and systematics by most of the malacologists that they obviously do not have because of their high plasticity. Molecular genetic methods allow a new interpretation of the importance of morphological and anatomical characters and a more objective definition of species and genera. Based on the new findings on variability of morphological characters a new determination key for the representatives of the genus Radix in central Europe was elaborated. It enables the determination of more Radix forms than it was previously possible with determination tools. Molecular genetic analyses of representatives of the genus Stagnicola revealed a high percentage of hybridisation. In practise, this has consequences for the application of barcoding on the base of mitochondrial markers (COI and cyt-b).

The subgenus Rexmela, located primarily in Florida, is newly evolved, dating back 1.6 million years, first occurring in the Ayer's Landing Member of the Caloosahatchee Formation. This subgenus has highly variably shell morphology and has led to the erection of several species and subspecies. In order to provide a quantitative methodology with which to differentiate between populations, samples of Recent and fossil populations were collected and measured for a variety of parameters. The parameters measured included length, width, spire height, and several angles, and allowed for a discriminate analysis to be completed. The analysis supported the distinction of several of the populations as ecophenotypes. Paleoenvironments of the fossil populations were then recreated using analogues of Recent populations. / by Crystal Pletka. / Thesis (M.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

by Amber L. Garr. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web. / The presence of heavy metals and other pollutants is detrimental to marine ecosystems. The queen conch, once an important fisheries species in the Florida Keys, has not sufficiently recovered after a 25-year fishery closure. Research has shown high levels of copper and zinc in the gonads and digestive glands of adult conch found in the nearshore waters. Four sites relevant to queen conch larval recruitment were tested in 2010 for the presence of copper and zinc in the water, phytoplankton, sediment, and seagrass epiphytes over seven months. Both metals were detected in all sample types and no seasonal or geographical differences were detected. Surface water concentrations from the field were used to conduct acute and chronic toxicity tests on various ages of queen conch larvae and their phytoplankton food source. When zinc concentrations (0-40 (So(Bg/L) similar to those measured in situ were used, there was no significant impact on conch larval survival although some velar lobe de velopment was impaired. However, field concentrations of copper (0-15 (So(Bg/L), which often surpassed water quality standards, negatively impacted growth, survival, and development of the larvae. Chronic exposure to copper, through the water and food, disrupted the metamorphic success of competent larvae and decreased post-metamorphosis survival. Exposure to copper at later life stages increased mortality, suggesting that heavy metals have a negative effect on larval recruitment in localized areas of the Florida Keys. Structural equation modeling revealed that copper and zinc are moving through the systems differently and are best represented by two different models.