Biologies of eight chrysidid species were described. These wasps parasitized bees and wasps collected in trap nests set at several sites in two canyons near Logan, Utah. The completed nests were taken to the laboratory and the parasitized ones were kept for study of the development a l biology and behavior of both host and parasites. The larval stages of Chrysura smaragdicolor, Chrysura sonorensis, Chrysis parkeri, Chrysis derivata, Chrysis coerulans, Cerotachrysis enhuycki, Trichrysis doriae and Hedychridium solierellae were studied. Omalus iridescens and Omalus purpuratus larvae were observed only in the fifth instar. The major differences between species or genera were found in the first instar larvae. The other larval instars differed in size but behaved similarly. The first instar larvae had a sclerotized, prognathous head, sharp sickle shape mandibles. When threatened the parasite larvae could escape quickly with the help of the forked appendages of the first segment. All the species except in Chrysura killed the host in the first instar and fed on the prey stored by their hosts. The Chrysura first instar attacked the host bee larva only after the latter had spun its cocoon. By the fifth instar all species of larvae had developed several teeth (two to three) at the distal end of each mandible. The hardening of these teeth coincided with the change of the food consistency from liquid to solid. The study also included a proposed evolutionary scheme of the possible pathway of morphological and behavioral characters that might ensure more successful parasitism.

The pre-metamorphic behaviors and settlement preferences of larvae can have significant effects on the success of adult invertebrates. This study describes various aspects of pre-metamorphic and post-metamorphic life stages of the bryozoan

Desenvolvimento e ciclo reprodutivo da bolacha-do-mar Clypeaster subdepressus (Echinodermata: Echinoidea) de São Sebastião, SP Resumo: Este trabalho descreve o desenvolvimento embrionário, larval e juvenil da bolacha-do-mar Clypeaster subdepressus sob microscopia de luz e eletrônica de varredura. Analisamos também o ciclo reprodutivo da espécie a partir de cortes histológicos das gônadas. A evolução morfológica da ordem Clypeasteroida (bolachas-do-mar), cerca de 55 milhões de anos atrás, esteve relacionada à ocupação de fundos arenosos. Dados morfológicos recentes e fósseis sugerem que durante a evolução das bolachas-do-mar houve retenção de características juvenis na fase adulta. Obtivemos gametas através da injeção de KCl em indivíduos adultos e fizemos a fecundação in vitro. Mantivemos os embriões e larvas em culturas a 26°C, e alimentamos as larvas com microalgas. Os óvulos (diâmetro médio de 160µm) são esféricos translúcidos e brancos. Após a entrada do espermatozóide, o envelope vitelínico endurece entre 2 e 6min; o pró-núcleo masculino inicia a migração da região periférica do óvulo até o centro 5min depois, levando 12min à 0,1µm/s para se fundir ao pró-núcleo feminino. As clivagens são holoblásticas, com a formação de macrômeros, mesômeros e micrômeros. A blástula forma-se entre 3,5 e 6,5h após a fecundação (hpf), desenvolve cílios e eclode da membrana de fertilização 7,5hpf. A gastrulação inicia-se na placa vegetativa com a ingressão unipolar das células mesenquimais primárias 10hpf. A extensão do arquêntero, ingressão das células mesenquimais secundárias e formação do esqueleto larval estendem-se até 30hpf. Em menos de 48hpf os espaços celômicos estão formados e no terceiro dia as larvas iniciam sua alimentação. O hidróporo abre-se na superfície abanal da larva e a invaginação do vestíbulo ocorre entre o braço pós-oral e o póstero-dorsal, do lado esquerdo, ao redor do quinto dia. O vestíbulo funde-se ao celoma esquerdo formando o rudimento, que desenvolve espinhos e pés ambulacrais ainda dentro da larva. As larvas tornam-se competentes ~20d após a fecundação e somente iniciam a metamorfose pela manhã, após contato com areia do habitat dos adultos ou microalgas. Após a eversão completa do rudimento, o epitélio larval regride por 1h30min. Jovens pós-metamórficos não têm boca ou ânus; possuem 15 espinhos e 15 pés ambulacrais (de 2 tipos); 5 esferídios na superfície oral; a superfície aboral ainda não possui esqueleto, exceto os remanescentes do esqueleto larval. Rudimentos do esqueleto da lanterna de Aristóteles estão organizados em 5 conjuntos com 1 dente, 2 hemipirâmides, 2 epífises cada; rudimento da rótula encontra-se intercalado entre os conjuntos. Hemipirâmides e dentes formam-se 2d após a metamorfose (dpm); dentes tornam-se mais robustos e as hemipirâmides se fundem formando as pirâmides 7dpm. O tubo digestório aparece e o ânus abre-se na superfície aboral 2dpm. A membrana peristomial torna-se funcional formando a boca 7dpm. Pedicelárias oficéfalas e tridentadas surgem na região posterior 14dpm e 30dpm, respectivamente. O crescimento dos jovens criados em laboratório foi lento: jovens pós-metamórficos tinham ~250µm de diâmetro e atingiram ~500µm de diâmetro 8 meses depois. Descrevemos 6 estágios de maturação gonadal para machos e fêmeas de C. subdepressus. Encontramos estágios de proliferação e gametas maduros com maior freqüência entre dezembro e março (verão), enquanto estágios de recuperação predominaram de maio a setembro (inverno). Fêmeas apresentaram um período de recuperação mais longo do que machos. A área ocupada pelo epitélio germinativo em um túbulo gonadal em corte transversal foi menor em indivíduos maduros. No estágio prematuro, as gônadas estiveram mais pesadas. Dados sugerem que exista um ciclo reprodutivo anual nas populações de C. subdepressus em São Sebastião, onde a recuperação das gônadas ocorre no inverno, o acúmulo de nutrientes a partir de outubro e a liberação de gametas entre fevereiro e março. / Embryonic, larval, and juvenile development of the sea biscuit Clypeaster subdepressus is described with light and scanning electron microscopy. The reproductive cycle of the species is analyzed based on histological sections of the gonads. The morphological evolution of the order Clypeasteroida (sand dollars and sea biscuits), about 55 million years ago, was associated with the occupation of sand beds. Data on morphology of living and fossil echinoids suggests that during the evolution of sea biscuits juvenile characters were retained into adulthood. We obtained ripe gametes by KCl injection into the perivisceral coelomic cavity of adults and fertilized the eggs in vitro. We kept embryos and larvae in cultures at 26 °C and fed larvae with microalgae. Eggs (mean diameter of 160 m) are spherical, translucent, and white. After sperm entry, the vitelline envelope hardens between 2 and 6 min; male pro-nucleus begins to migrate towards the center of the egg 5 min later, taking 12 min at 0.1 m/s to fuse with the female pronucleus. Cleavages are holoblastic with the formation of macromeres, mesomeres, and micromeres. Blastulae are formed between 3.5 and 6.5 h after fertilization (hpf), develop cilia, and hatch 7.5 hpf. Gastrulation begins on the vegetal plate with the unipolar ingression of primary mesenchyme cells 10 hpf. Archenteron extension, ingression of secondary mesenchyme cells, and the formation of larval skeleton occurs until 30 hpf. In less than 48 hpf the celomic pouches are formed and on day 3 larvae begin to feed. Hidropore opens on the abanal surface of larvae while vestibule invagination takes place between the post-oral and postero-dorsal arms on the left side 5 dpf. Vestibule fuses with the left celom forming a rudiment which develops spines and podia still inside the larvae. Larvae become competent _20 d after fertilization and only metamorphose in the morning, after contact with sand from adult populations or food. After complete eversion of the rudiment, the larval epidermis retraction takes 1 h 30 min. Post-metamorphic juveniles do not have anus or mouth; they have 15 spines and 15 podia (of 2 types); 5 sphaeridia on the oral surface; aboral surface does not have plates, except for the remnants of larval spicules. Rudiments of the Aristotles lantern are organized in 5 groups. Each group has 1 tooth, 2 hemipiramids, and 2 epiphysis; a rudiment rotula is placed between the groups. Hemipiramids are formed 2 d after metamorphosis (dpm); teeth become more robust and hemipiramids fuse into piramids 7 dpm. The digestive tract appears and the anus opens on the aboral surface 2 dpm. The peristomial membrane is functional and the mouth opens 7 dpm. Ophicephalous and tridentate pedicellariae appear on the posterior region 14 dpm and 30 dpm, respectively. Growth of juveniles reared in the laboratory was slow: post-metamorphic juveniles were _250 m in diameter and reached _500 m 8 months later. We described 6 stages of gonadal growth in males and females of C. subdepressus. We found premature stages and ripe gametes more frequently between December and March (summer), while recovery stages were dominant from May until September (winter). Females have a longer period of growing stage than males. The area occupied by the germinal epithelium on a transverse section of a gonadal lobe is lower in mature stage. Gonads are heavier during the premature stage. Data suggest that C. subdepressus from São Sebastião has an annual reproductive cycle where gonadal recovery occurs during winter, nutrient storage by October, and spawning between February and March.

A interação mutualística, espécie-especifica, vespas de figo-figueiras envolve dois processos antagonísticos, predação de sementes e polinização, realizadas por vespas da família Agaonidae. Sabe-se que a larva da vespa se alimenta de tecido da semente durante seu desenvolvimento, mas o processo pelo qual isto ocorre é pouco conhecido, não se sabendo até que ponto a larva depende do desenvolvimento da semente. Neste trabalho foi estudada a biologia larval de Pegoscapus tonduzi, polinizadora de Ficus citrifolia (Moraceae). O estudo foi realizado em plantas de F. citrifolia presentes no campus da Universidade de São Paulo em Ribeirão Preto/SP, durante o período de julho de 2007 a agosto de 2008. Para tal, quatro coortes de vespas foram estudas, nas quais cerca de cinco figos foram coletados em intervalos de dois dias, ao longo do ciclo de desenvolvimento larval. Os figos foram dissecados para observação das larvas e para a obtenção de ovários/galhas da planta para o preparo de lâminas histológicas. Os resultados mostraram que o processo de predação de sementes realizado pelas larvas de P. tonduzi é elaborado, com o desenvolvimento larval intimamente relacionado aos processos embriogênicos da planta. O desenvolvimento larval apresenta quatro instares, detectados pela mudança de tamanho e formadas larvas. A duração do ciclo de vida de P. tonduzi foi de 40 a 70 dias, aproximadamente, correlacionando-se negativamente com a temperatura ambiente no período. O ovo é depositado na região próxima à base do estilete, entre o nucelo e o tegumento interno do ovário da planta. Nessa fase, observase o surgimento do embrião vegetal, indicando que o ovário em que larva se desenvolve foi fertilizado. No segundo estádio larval, o inseto migra para a região micropilar e passa a se alimentar oralmente do endosperma da planta. Nesta fase, ainda, nota-se o desaparecimento do embrião vegetal, sugerindo que este é consumido pela larva da vespa. Os resultados sugerem a existência de um ajuste evolutivo fino entre inseto-planta, uma vez que o desenvolvimento da larva da vespa de figo parece depender da fertilização e conseqüente formação do endosperma. / The species-specific mutualistic interaction between fig trees and fig wasps engages two antagonist processes: seed predation and pollination, both achieved by wasps of the Agaonidae family. It is well known that fig wasp larvae feed on seed tissues for their development but the process itself is poorly known. Here is a study on the larval biology of Pegoscapus tonduzi, pollinator of Ficus citrifolia (Moraceae). The study was carried out between July 2007 and August 2008 at the Sao Paulo University campus in Ribeirao Preto, Sao Paulo State. Four cohorts of fig wasps were studied; for each cohort, about five figs were sampled each two days until complete larval cycle. Sampled figs were dissected for larvae observation and measurement, and flower ovaries/galls subsamples destined to histological study. Results showed that seed predation by fig wasps is a complex process, with larval development closely related to plant embryogenesis. Four larval instars were determined by changes on larva size and shape. Larval cycle extended from 40 to 70 days, showing a negative relation with environmental temperature. The egg is laid near the style insertion, between nucleus and inner integument of the flower ovary. Vegetal embryo was observed along with first larval instar, indicating that fertilization took place inside the ovary where larva develops. At second instar, the larva migrates to the micropilar region and begins to feed orally from endosperm. In this phase, the embryo disappears, suggesting that it is consumed by the larva. Our results suggest a fine tune evolutionary insect-plant adjustment, as fig wasp larvae seems to depend on ovary fertilization and endosperm development.

A interação mutualística, espécie-especifica, vespas de figo-figueiras envolve dois processos antagonísticos, predação de sementes e polinização, realizadas por vespas da família Agaonidae. Sabe-se que a larva da vespa se alimenta de tecido da semente durante seu desenvolvimento, mas o processo pelo qual isto ocorre é pouco conhecido, não se sabendo até que ponto a larva depende do desenvolvimento da semente. Neste trabalho foi estudada a biologia larval de Pegoscapus tonduzi, polinizadora de Ficus citrifolia (Moraceae). O estudo foi realizado em plantas de F. citrifolia presentes no campus da Universidade de São Paulo em Ribeirão Preto/SP, durante o período de julho de 2007 a agosto de 2008. Para tal, quatro coortes de vespas foram estudas, nas quais cerca de cinco figos foram coletados em intervalos de dois dias, ao longo do ciclo de desenvolvimento larval. Os figos foram dissecados para observação das larvas e para a obtenção de ovários/galhas da planta para o preparo de lâminas histológicas. Os resultados mostraram que o processo de predação de sementes realizado pelas larvas de P. tonduzi é elaborado, com o desenvolvimento larval intimamente relacionado aos processos embriogênicos da planta. O desenvolvimento larval apresenta quatro instares, detectados pela mudança de tamanho e formadas larvas. A duração do ciclo de vida de P. tonduzi foi de 40 a 70 dias, aproximadamente, correlacionando-se negativamente com a temperatura ambiente no período. O ovo é depositado na região próxima à base do estilete, entre o nucelo e o tegumento interno do ovário da planta. Nessa fase, observase o surgimento do embrião vegetal, indicando que o ovário em que larva se desenvolve foi fertilizado. No segundo estádio larval, o inseto migra para a região micropilar e passa a se alimentar oralmente do endosperma da planta. Nesta fase, ainda, nota-se o desaparecimento do embrião vegetal, sugerindo que este é consumido pela larva da vespa. Os resultados sugerem a existência de um ajuste evolutivo fino entre inseto-planta, uma vez que o desenvolvimento da larva da vespa de figo parece depender da fertilização e conseqüente formação do endosperma. / The species-specific mutualistic interaction between fig trees and fig wasps engages two antagonist processes: seed predation and pollination, both achieved by wasps of the Agaonidae family. It is well known that fig wasp larvae feed on seed tissues for their development but the process itself is poorly known. Here is a study on the larval biology of Pegoscapus tonduzi, pollinator of Ficus citrifolia (Moraceae). The study was carried out between July 2007 and August 2008 at the Sao Paulo University campus in Ribeirao Preto, Sao Paulo State. Four cohorts of fig wasps were studied; for each cohort, about five figs were sampled each two days until complete larval cycle. Sampled figs were dissected for larvae observation and measurement, and flower ovaries/galls subsamples destined to histological study. Results showed that seed predation by fig wasps is a complex process, with larval development closely related to plant embryogenesis. Four larval instars were determined by changes on larva size and shape. Larval cycle extended from 40 to 70 days, showing a negative relation with environmental temperature. The egg is laid near the style insertion, between nucleus and inner integument of the flower ovary. Vegetal embryo was observed along with first larval instar, indicating that fertilization took place inside the ovary where larva develops. At second instar, the larva migrates to the micropilar region and begins to feed orally from endosperm. In this phase, the embryo disappears, suggesting that it is consumed by the larva. Our results suggest a fine tune evolutionary insect-plant adjustment, as fig wasp larvae seems to depend on ovary fertilization and endosperm development.

Desenvolvimento e ciclo reprodutivo da bolacha-do-mar Clypeaster subdepressus (Echinodermata: Echinoidea) de São Sebastião, SP Resumo: Este trabalho descreve o desenvolvimento embrionário, larval e juvenil da bolacha-do-mar Clypeaster subdepressus sob microscopia de luz e eletrônica de varredura. Analisamos também o ciclo reprodutivo da espécie a partir de cortes histológicos das gônadas. A evolução morfológica da ordem Clypeasteroida (bolachas-do-mar), cerca de 55 milhões de anos atrás, esteve relacionada à ocupação de fundos arenosos. Dados morfológicos recentes e fósseis sugerem que durante a evolução das bolachas-do-mar houve retenção de características juvenis na fase adulta. Obtivemos gametas através da injeção de KCl em indivíduos adultos e fizemos a fecundação in vitro. Mantivemos os embriões e larvas em culturas a 26°C, e alimentamos as larvas com microalgas. Os óvulos (diâmetro médio de 160µm) são esféricos translúcidos e brancos. Após a entrada do espermatozóide, o envelope vitelínico endurece entre 2 e 6min; o pró-núcleo masculino inicia a migração da região periférica do óvulo até o centro 5min depois, levando 12min à 0,1µm/s para se fundir ao pró-núcleo feminino. As clivagens são holoblásticas, com a formação de macrômeros, mesômeros e micrômeros. A blástula forma-se entre 3,5 e 6,5h após a fecundação (hpf), desenvolve cílios e eclode da membrana de fertilização 7,5hpf. A gastrulação inicia-se na placa vegetativa com a ingressão unipolar das células mesenquimais primárias 10hpf. A extensão do arquêntero, ingressão das células mesenquimais secundárias e formação do esqueleto larval estendem-se até 30hpf. Em menos de 48hpf os espaços celômicos estão formados e no terceiro dia as larvas iniciam sua alimentação. O hidróporo abre-se na superfície abanal da larva e a invaginação do vestíbulo ocorre entre o braço pós-oral e o póstero-dorsal, do lado esquerdo, ao redor do quinto dia. O vestíbulo funde-se ao celoma esquerdo formando o rudimento, que desenvolve espinhos e pés ambulacrais ainda dentro da larva. As larvas tornam-se competentes ~20d após a fecundação e somente iniciam a metamorfose pela manhã, após contato com areia do habitat dos adultos ou microalgas. Após a eversão completa do rudimento, o epitélio larval regride por 1h30min. Jovens pós-metamórficos não têm boca ou ânus; possuem 15 espinhos e 15 pés ambulacrais (de 2 tipos); 5 esferídios na superfície oral; a superfície aboral ainda não possui esqueleto, exceto os remanescentes do esqueleto larval. Rudimentos do esqueleto da lanterna de Aristóteles estão organizados em 5 conjuntos com 1 dente, 2 hemipirâmides, 2 epífises cada; rudimento da rótula encontra-se intercalado entre os conjuntos. Hemipirâmides e dentes formam-se 2d após a metamorfose (dpm); dentes tornam-se mais robustos e as hemipirâmides se fundem formando as pirâmides 7dpm. O tubo digestório aparece e o ânus abre-se na superfície aboral 2dpm. A membrana peristomial torna-se funcional formando a boca 7dpm. Pedicelárias oficéfalas e tridentadas surgem na região posterior 14dpm e 30dpm, respectivamente. O crescimento dos jovens criados em laboratório foi lento: jovens pós-metamórficos tinham ~250µm de diâmetro e atingiram ~500µm de diâmetro 8 meses depois. Descrevemos 6 estágios de maturação gonadal para machos e fêmeas de C. subdepressus. Encontramos estágios de proliferação e gametas maduros com maior freqüência entre dezembro e março (verão), enquanto estágios de recuperação predominaram de maio a setembro (inverno). Fêmeas apresentaram um período de recuperação mais longo do que machos. A área ocupada pelo epitélio germinativo em um túbulo gonadal em corte transversal foi menor em indivíduos maduros. No estágio prematuro, as gônadas estiveram mais pesadas. Dados sugerem que exista um ciclo reprodutivo anual nas populações de C. subdepressus em São Sebastião, onde a recuperação das gônadas ocorre no inverno, o acúmulo de nutrientes a partir de outubro e a liberação de gametas entre fevereiro e março. / Embryonic, larval, and juvenile development of the sea biscuit Clypeaster subdepressus is described with light and scanning electron microscopy. The reproductive cycle of the species is analyzed based on histological sections of the gonads. The morphological evolution of the order Clypeasteroida (sand dollars and sea biscuits), about 55 million years ago, was associated with the occupation of sand beds. Data on morphology of living and fossil echinoids suggests that during the evolution of sea biscuits juvenile characters were retained into adulthood. We obtained ripe gametes by KCl injection into the perivisceral coelomic cavity of adults and fertilized the eggs in vitro. We kept embryos and larvae in cultures at 26 °C and fed larvae with microalgae. Eggs (mean diameter of 160 m) are spherical, translucent, and white. After sperm entry, the vitelline envelope hardens between 2 and 6 min; male pro-nucleus begins to migrate towards the center of the egg 5 min later, taking 12 min at 0.1 m/s to fuse with the female pronucleus. Cleavages are holoblastic with the formation of macromeres, mesomeres, and micromeres. Blastulae are formed between 3.5 and 6.5 h after fertilization (hpf), develop cilia, and hatch 7.5 hpf. Gastrulation begins on the vegetal plate with the unipolar ingression of primary mesenchyme cells 10 hpf. Archenteron extension, ingression of secondary mesenchyme cells, and the formation of larval skeleton occurs until 30 hpf. In less than 48 hpf the celomic pouches are formed and on day 3 larvae begin to feed. Hidropore opens on the abanal surface of larvae while vestibule invagination takes place between the post-oral and postero-dorsal arms on the left side 5 dpf. Vestibule fuses with the left celom forming a rudiment which develops spines and podia still inside the larvae. Larvae become competent _20 d after fertilization and only metamorphose in the morning, after contact with sand from adult populations or food. After complete eversion of the rudiment, the larval epidermis retraction takes 1 h 30 min. Post-metamorphic juveniles do not have anus or mouth; they have 15 spines and 15 podia (of 2 types); 5 sphaeridia on the oral surface; aboral surface does not have plates, except for the remnants of larval spicules. Rudiments of the Aristotles lantern are organized in 5 groups. Each group has 1 tooth, 2 hemipiramids, and 2 epiphysis; a rudiment rotula is placed between the groups. Hemipiramids are formed 2 d after metamorphosis (dpm); teeth become more robust and hemipiramids fuse into piramids 7 dpm. The digestive tract appears and the anus opens on the aboral surface 2 dpm. The peristomial membrane is functional and the mouth opens 7 dpm. Ophicephalous and tridentate pedicellariae appear on the posterior region 14 dpm and 30 dpm, respectively. Growth of juveniles reared in the laboratory was slow: post-metamorphic juveniles were _250 m in diameter and reached _500 m 8 months later. We described 6 stages of gonadal growth in males and females of C. subdepressus. We found premature stages and ripe gametes more frequently between December and March (summer), while recovery stages were dominant from May until September (winter). Females have a longer period of growing stage than males. The area occupied by the germinal epithelium on a transverse section of a gonadal lobe is lower in mature stage. Gonads are heavier during the premature stage. Data suggest that C. subdepressus from São Sebastião has an annual reproductive cycle where gonadal recovery occurs during winter, nutrient storage by October, and spawning between February and March.

xix, 166 p. : ill. / The nemertean worm Carcinonemertes errans is an egg predator on the Dungeness crab, Cancer magister, an important fishery species along the west coast of North America. This study examined the estuarine distribution and larval biology of C. errans. Parasite prevalence and mean intensity of C. errans infecting C. magister varied along an estuarine gradient in the Coos Bay, Oregon. Crabs nearest the ocean carried the heaviest parasite loads, and larger crabs were more heavily infected with worms. Seasonal infection patterns were seen at some sites within the bay. Crabs from coastal waters carried significantly more worms than did crabs from the bay, suggesting that the estuary may be acting as a parasite refuge for estuarine crabs. In laboratory experiments, C. errans all died in salinities below 10 within 6 days, but C. errans showed some tolerance to salinities 20 and above. These results suggest that salinity alone does not likely account for the estuarine gradient of C. errans in Coos Bay. Larvae of C. errans raised from hatching never settled in the laboratory. Competent larvae taken in plankton tows were morphologically distinct from larvae raised in laboratory cultures and did settle successfully on C. magister under laboratory conditions. Initial settlement was reversible within a 24-hour window. After 48 hours, a non-reversible metamorphosis occurred wherein worms lost one pair of eyes and the propensity to swim. In field settlement experiments, C. errans was capable of infecting hosts from the water column and preferred to settle on crabs already infected with juvenile worms, although this preference was density dependent. In monthly plankton tows, larvae of C. errans were found only between August and November, suggesting a long larval life for this species. Larvae did not feed under laboratory conditions, nor did they absorb dissolved organics. When exposed to a natural angular light distribution, larvae of C. errans were rarely photopositive. Larvae were most sensitive to blue-green light. Low intensity light invoked a photonegative response. Larvae were geopositive at hatching but geonegative thereafter. / Committee in charge: Brendan Bohannan, Chairperson; Craig Young, Advisor; Svetlana Maslakova, Member; Alan Shanks, Member; William Orr Outside, Member

This thesis describes the results of a three year study which collected larvae of the acorn barnacles Semibalanus balanoides on a rocky coastline in Fife, East Scotland. The nauplii larvae of S. balanoides are released from their parent in springtime in the United Kingdom and develop in the plankton for approximately one to two months. During this period they are transported some distance from the parent population and eventually return to the intertidal shoreline as a cyprid larval stage. The ‘decision’ to settle is a crucial point in the life history of the organism as most sessile organisms cannot move once this has occurred. The supply of larvae to intertidal shorelines was historically neglected until the 1980s. Patterns of settlement were largely considered irrelevant to distribution patterns of adults relative to postsettlement processes such as predation and competition. Despite the resurgence in “supply-side ecology” in the past 20 years there has been little development towards the measurement of larval supply. Consequently there has been very little description of fine scale or large spatio-temporal studies involving larval supply. This study demonstrates the first study directly addressing larval supply independently from larval settlement at mesoscales (metres to kilometres; days to years). Improvements were made to the passive larval trap described by Todd (2003). A conical opening was combined with the spiral trap design and a number of inlet areas were trialled (0.25cm², 0.5cm², 1cm² and 2cm²). These were tested across typical wave regimes measured with a new autonomous pressure sensing wave transducer and the 1cm² inlet was selected as the most appropriate trap design due to a balance between an increased per unit inlet larval capture and sufficient absolute larval capture so as to identify daily variation in larval supply to a site. Larval settlement has been studied extensively and is often used as a direct measure of rates of larval supply. It is widely assumed therefore that rates of settlement are a direct reflection of rates of supply, as long as settlement substrates and adult conspecific responses remain uniform. This thesis provides a means of accurately characterising the supply-settlement relationship for S. balanoides independent of substrate based responses and demonstrates that this is not the case. The relationship was found to be asymptotic, even at sites where there was low larval supply. It was concluded that density-dependent larva-larva interactions were present during the settlement of larvae and were relevant at daily temporal scales, limiting the rates of larval settlement proportional to larval density. There was no obvious effect on this relationship due to wave action however differences were observed between sites and years. Saturation of preferential environments within the tiles was observed resulting in a settlement preference cascade, with larvae being forced to settle in increasingly less preferable areas of the tiles with increasing larval density. Larva-larva interactions are demonstrated as having a considerable effect on the rates of settlement of S. balanoides.