Thesis (Ph. D.)--Rhodes University, 2003. / Title from PDF t.p. (viewed on Apr. 30, 2006). Includes bibliographica references.

Thesis (Ph. D. (Ichthyology & Fisheries Science))--Rhodes University, 2004.

No description available.

I head to the ocean for inspiration. Diving deep, the diverse organic shapes and fluidity of the flora and fauna inspire me to create modular pieces that incorporate intricate line work. This repetitive line and patterning gives me peace and helps me meditate. This self-exploration has opened up a stimulating world that pushes me to produce prints and silver jewelry that are individual and introspective. I have learned that the journey has become the aspiration and the production, a gift.

Orientadora : Profª. Drª. Érica Alves Gonzáles Vidal / Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Sistemas Costeiros e Oceânicos. Defesa: Pontal do Paraná, 26/04/2013 / Inclui referências / Resumo: O polvo comum Octopus vulgaris tem se tornado um dos cefalópodes mais estudados, devido ao seu alto valor comercial e à crescente demanda como recurso marinho em muitos países. O estudo das relações entre sua estrutura populacional e os fatores ambientais que a determinam é de fundamental importância para um maior conhecimento de sua ecologia, possibilitando a criação de medidas de conservação e manejo eficazes. Devido à presença de O. vulgaris na Marina Ponta do Poço (25°32?822?S; 48°23?283?O), dentro do Complexo Estuarino de Paranaguá e a falta de informações sobre sua dinâmica populacional, o presente estudo teve por objetivo realizar uma descrição hidrográfica do local, determinar a distribuição e abundância relativa de paralarvas, densidade de juvenis e adultos, proporção sexual e determinar o estágio de maturação gonadal dos indivíduos. Entre agosto de 2012 e janeiro de 2013, a temperatura da água variou de 19 a 28 °C e a salinidade entre 23 e 34. As velocidades de corrente tiveram máximas de 120 cm s-1 na maré vazante e 73 cm s-1 durante a enchente. A densidade de paralarvas variou entre 0 e 0,033 ind. m-3, e durante os mergulhos para o censo visual, foi estimada uma abundância relativa de polvos de 0 a 0,023 ind. m-2. Machos e fêmeas não apresentaram diferenças significativas quanto às médias de peso, comprimento do manto e distância entre os olhos, e as variáveis biométricas foram altamente correlacionadas entre si. A proporção sexual não diferiu significativamente de 1:1, e o estágio III (maturo) foi o mais frequente na primavera, sendo substituído pelos estágios I (imaturo) e II (em maturação) no verão. Os resultados mostraram que na primavera e verão há uma agregação reprodutiva de O. vulgaris na Marina Ponta do Poço, local que oferece condições favoráveis em termos de disponibilidade de abrigo e alimento, propiciando a ocorrência desde juvenis imaturos, adultos maturos, desova e eclosão das paralarvas. Além disso, as características hidrográficas permitem uma ampla dispersão de paralarvas, favorecendo uma distribuição ainda maior de O. vulgaris no Complexo Estuarino de Paranaguá, fundamental para a manutenção da população de polvos na região. Palavras-chave: Octopus vulgaris, estrutura populacional, abundância, paralarva, características hidrográficas. / Abstract: The common octopus Octopus vulgaris has become one of the most studied and well known cephalopod species due to its high commercial value and the rising market demand for this marine resource in many countries. The study of the relationship between O. vulgaris population structure and the environmental factors which determine it is fundamental for a better understanding of the ecology of the species, allowing for the creation of effective measures for its conservation and management. Given the presence of O. vulgaris in the Ponta do Poço Marina (25°32?822?S; 48°23?283?O), inside the Paranaguá Estuarine Complex, and the lack of information on its population dynamics on the coast of Paraná, this study presents a hydrographic description for the named location; an estimation of paralarval abundance; and data on juvenile and adult density, sexual proportion, biometric measurements, and individual gonadal maturation stage. Water mean temperature varied from 19 to 28 °C between August 2012 and January 2013, and salinity varied between 23 and 34. Current speed reached a maximum of 120 and 73 cm s- 1 during ebb and flood tides, respectively. Paralarval density varied from 0 to 0.033 ind. m- 3, and during visual census through SCUBA diving the relative abundance of juveniles and adults was estimated from 0 to 0.023 ind. m-2. Males and females did not show significant difference as to the mean values in weight, mantle length, and distance between the eyes, and the biometric variables were highly correlated between themselves. The sexual proportion did not differ significantly from 1:1, and the stage III (mature) was the most frequently seen during spring, while stages I (immature) and II (maturing) were the most frequent during summer. The results show that there is a reproductive aggregation of O. vulgaris at the Marina Ponta do Poço during spring and summer, a place which offers favorable conditions in terms of shelter and food availability, favoring the occurrence since immature juveniles, mature adults, spawning and paralarval hatching. Moreover, the hydrographic characteristics allow a wide dispersion of the paralarvae, providing a great distribution of O. vulgaris in Paranaguá Estuarine Complex, which is essential to maintain the population of octopuses in the region. Keywords: Octopus vulgaris, population structure, abundance, paralarvae, hydrographic characteristics.

Catch dynamics, fisheries biology and socio-economic dependence are described for the artisanal fishery for Octopus cyanea at three study sites (Kwale. Jibondo, and Mtwara) along the coat of Tanzania. A total of 23,165 octopuses were measured and sexed from 3,514 individual catches. FIShing effort was shown to be 2.9 times greater at Msangamkuu compared to Jibondo and nearly two times more than Kwale. Number of relaxation days between fishing events, when the octopus stock are able to recover through growth and immigration, was shown to be greater at Iibondo than for the other two sites. Marked reductions in catch landings, mean individual weight, catch per unit effort (kg) and size distributions are reported for Msangamkuu and Kwale when compared to Jibondo. Abundance of octopus was however, higher at the former sites most likely in response to predator and competition release. Stock size and biomass (kg) were calculated for Msangamkuu using a De-Lury depletion method and results extrapolated to the other two sites. Despite higher abundance at Msangamkuu and Kwale mean overall biomass (kg) was 36% and 14% respectively lower tban the mean biomass estimate for Jibondo. Spatial comparison of fishing impacts between sites using a surplus production model suggested Jibondo to be more productive and fishing pressure sustainable. In contrast, Msangamkuu was indicated to be seriously overtished and Kwale somewhere in between. Although, Bhattacharya modal progression analyses separated multiple size modes in monthly samples growth analyses were unsuccessful due to the lack of a clear corresponding pattern of modal progression in monthly size distributions. Length weight relationships varied between sites and sexes. All length weight relationships were negative allometric. Size reductions at Kwale and Msangambru may be impacting on reproductive output with a 40% reduction in the number of mature males at Msangamkuu and 24% reduction at Kwale when compared to Jibondo. Fewer mature females were observed at Msangamkuu and Kwale but even at Jibondo mature females accounted for only 2.2% of the catch. Results suggest spawning activity takes place in deeper water ( > 4m) below the fisbed zone. Nonetheless, enough females would have to reach brooding size at each site to contribute to the reproductive stock. Size at first maturity for females was estimated to be 1800g. Only 3.9% of the octopus at Kwale and 1.2% at Msangamkuu weigh more than 1800g compared to 17% at Jibondo. Fecundity was shown to increase with size. Breeding activity is likely to be year round but maturity peaks were evident for June and July and October to November. The den enrichment experiment indicated a clear preference for concrete dens over PVC pipe. Overall density increased by 10% subsequent to den placement but dens were shown in reef areas not to be limiting. The benefit of den enrichment was therefore ambiguous but could be initiated using a phased approach to gauge effectiveness. The artisanal octopus fisheries make an important contnbution to the local economy. population growth and fisher and trader immigrations were noted as the greatest threats to the octopus fishery by fishers. Awareness of relevant marine resource use issues was shown to be high yet enthusiasm for management varied between sites. The first descriptive details of the octopus fauna of Tanzania are provided. Implications for management of the octopus fishery and a series of proposed management actions are provided for discussion between relevant stakeholders.

No description available.

No description available.

Cistopus sp. is a medium to large octopod and it is common in the fish markets of Taiwan. The diagnostic character of the genus Cistopus is the possession of eight mucous pouches in the web between the base of each arm. However, researches on this special structure were absent. This study is to describe the morphological characters of Cistopus sp. from Taiwanese waters and to examine the mucous pouch histologically. The mitochondrial COI gene sequences are used as a tool to analyze the phylogenetic relationships between Cistopus and other genera of the family Octopodidae. Based on the results of this study, the Cistopus of Taiwanese waters is different from the genuine C. indicus and the Cistopus of the Andaman Sea. Cistopus sp. is widely distributed from coastal Asia to India at least and presents sexual dimorphism in the openings of the mucous pouches. The inner wall of the mucous pouches is composed of columnar epithelial cells, and the mucus is secreted from the epithelial cells. The substance secreted from the inner wall is acid mucopolysaccharides. According to the phylogenetic analysis of the octopods COI DNA sequences, Cistopus is grouped with other members of subfamily Octopodinae to form a monophyletic group.

Reliable quantities of blood can be sampled repeatedly from the lesser octopus Eledone cirrhosa (Lam. ) and the haemocytes cultured for up to 72 h. Sampling causes an increase in the number of haemocytes/ml, in the percentage of haemocytes containing cytoplasmic granules and a change in the staining pattern of the haemocytes. Sampling also causes a decrease in the amount of copper (mg/ml) in the haemolymph and an initial decrease in the amount of protein (mg/ml), which returns to the original values over extended sampling periods. The haemocytes from E. cirrhosa will phagocytose bacteria (Vibrio anguillarum) in vitro in the absence of haemolymph (dependent on the temperature and duration of incubation) but enhanced phagocytosis will occur in the presence of haemolymph (10- 100% concentration). Opsonization is also dependent on the temperature and on the duration of exposure of the bacterium to the haemolymph. Haemocytes migrate towards low concentrations of blood preparations, to lipopolysaccharide (LPS) and to preparations which had contained live bacteria. Haemocytes also have a bacteriostatic effect on the growth of live bacteria with the effect being dependent on the temperature, duration of the assay and the bacterial species used. Haemocytes also produce intracellular reactive oxygen species, detected by nitroblue tetrazolium, after incubation with dead bacteria in particular, but also live bacteria and LPS. E. cirrhosa haemolymph agglutinates the bacteria V. anguillarum, Y. parahaemolyticus and Aeromonas salmonicida and exerts a bacteriostatic effect on these bacteria which is dependent on the temperature, the amount of haemolymph present and the bacterial species used. The haemolymph, haemocytes and certain tissues from E. cirrhosa exhibit lysozyme and antiprotease activity. The injection of live V. anguillarum causes an increase in lysozyme activity in the branchial heart (after 48 h) and a decrease in the haemocytes (after 24 h). Antiprotease activity increased in the haemocytes (4 h) after bacterial injection but decreased in the haemolymph. Live bacteria caused an increase in the number of circulating haemocytes. The bacteria were cleared from the circulation of E. cirrhosa in about 4h by both the haemocytes and tissues (branchial heart, branchial heart appendage and white body) where they were degraded. The large vacuole in branchial heart cells changed in appearance 4h after bacterial injection and the haemocyte nucleus became pleomorphic. Colloidal graphite was aggregrated in blood vessels only.