Thesis (Ph.D.) -- University of Western Sydney, 2003. / "Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 76-83). Also available via the Internet.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Restricted until May 2003. Bibliography: leaves 135-141.

Thesis (M. Sc. (Zoology & Entomology))--Rhodes University, 2005.

Thesis (Ph. D.)--Rhodes University, 2005. / Title from PDF t.p. (viewed on July 21, 2006). Includes bibliographical references (p. 251-270).

Η παρούσα μελέτη διερευνά την ικανότητα των πολυκυκλικών αρωματικών υδρογονανθράκων να (PAHs), όπως είναι το φαινανθρένιο και το ανθρακένιο, να επάγουν συνθήκες stress (stress syndrome) σε ιστούς (π.χ. βράγχια) του είδους Mytilus galloprovincialis. Σύμφωνα με τα αποτελέσματα αυτής της μελέτης, τα μύδια τα οποία εκτέθηκαν για 7 ημέρες σε PH και/ή AN (τελικής συγκέντρωσης 0,1 mg/L σε κάθε περίπτωση) καθώς και σε μίγμα αυτών των οργανικών ρύπων (τελικής συγκέντρωσης 0,2 mg/L), παρουσίασαν αυξημένη συχνότητα εμφάνισης πυρηνικών ανωμαλιών, όπως είναι οι μικροπυρήνων (MN), και επαγωγή νευρολογικών διαταραχών, πράγμα που υποδεικνύεται από την μέτρηση της δραστικότητας της ακετυλχολινεστεράσης (AChE). Επιπλέον, τα αυξημένα επίπεδα της MDA στα βράγχια των εκτιθέμενων ατόμων καθώς και η μείωση του χρόνου ημιζωής (LT50) των μυδιών που εκτέθηκαν στον αέρα (τεχνική Stress on Stress), αντανακλούν στις οξειδωτικές επιπτώσεις που επάγουν οι πολυκυκλικοί αρωματικοί υδρογονανθράκες στους ιστούς των εκτιθέμενων στον αέρα μυδιών, πράγμα που οδηγεί στην επαύξηση των τοξικών επιδράσεων, σε διαφορετικά επίπεδα της λειτουργίας του οργανισμού. / This study investigates the ability of certain polycyclic aromatic hydrocarbons (PAHs), such as phenanthrene (PH) and anthracene (AN), to induce stress conditions (stress syndrome) in tissues (e.g. gills) of mussel Mytilus galloprovincialis. According to the results of this study, mussels exposed for 7 days to PH and/or AN (at a final concentration of 0,1mg/L in each case) as well as to a mixture of these organic pollutants (at a final concentration of 0,2 mg/L) showed increased frequencies of nuclear abnormalities, such as the presence of micronuclei (MN), and induction of neurological disorders, as shown by measuring the activity of acetylcholinesterase (AChE). Furthermore, increased levels of MDA in the gills of exposed individuals, and the reduction of the lethal time (LT50) of challenge mussels superimposed in air (Stress on Stress technique), merely reflect PAHs-induced oxidative effects on tissues of challenge mussels, thus leading to the enhancement of toxic effects to different levels of organism function.

Plusieurs habitats de l'Océan profond sont caractérisés par la présence de composés chimiques réduits. Les communautés benthiques prospèrent dans ces "habitats réducteurs", en raison de liens trophiques avec des bactéries chimiosynthétiques, qui tirent l'énergie de donneurs (sulfures, hydrocarbures) et accepteurs (O2) d'électrons. Les moules bathymodiolines sont un taxon clé dans ces habitats. À l'âge adulte, presque toutes possèdent des bactéries symbiotiques, mais les données sont rares concernant leur cycle de vie. Cette recherche explore la biologie de la reproduction, le développement et la nutrition dans le cycle de vie des espèces Idas modiolaeformis et "I." simpsoni. Les analyses anatomiques, histologiques et moléculaires à divers stades du développement sont associées à des observations in vivo. Une comparaison est proposée entre ces espèces. Chez les deux, les post-larves n'ont pas de symbiotes, suggérant des larves strictement hétérotrophes. L'infection par les symbiotes est environnementale, extracellulaire et initialement non-spécifique, se restreignant aux surfaces latéro-abfrontales des filaments branchiaux chez les adultes. La maturation est rapide, de même que la transition de l'hétérotrophie à la mixotrophie chimiosymbiotique: les symbioses, l'alimentation par filtration, et la rétention d'un système digestif complet coïncident. Les différences entre espèces et habitats sont discutées dans le contexte de leur évidente réussite évolutive à s'adapter aux habitats réduits et éphémères de l'Océan profond. / An array of deep-sea habitats are characterised by thermo- and/or biogenic production of chemically reduced compounds. Benthic communities thrive at these ‘reducing habitats’, due to trophic links to free-living and symbiotic chemosynthetic bacteria which derive energy from electron donors (sulphides, hydrocarbons) and acceptors (O2), at reduction-oxidation boundaries. The bathymodiolin mytilids (sensu lato) are a keystone taxon in these habitats; all-but-one species host gill-associated symbiotic Gammaproteobacteria as adults, but data are scarce on the remaining lifecycle, particularly at organic falls. To understand how mussels are adapted to these habitats, this research characterises the reproductive, developmental and nutritional lifecycle biology of two species, Idas modiolaeformis and I. simpsoni. Anatomical, histological and molecular analyses on post-larval-to-adult size spectra are complemented with live observations. Contrasting and converging aspects of their biology and symbioses are presented. In both species, aposymbiotic post-larvae confirm strict, larval heterotrophy. While still very small, environmental symbiont infection is extracellular and initially non-specific, becoming progressively isolated to latero-abfrontal gill surfaces in adults. Maturation is rapid, in parallel with a transition from heterotrophy to chemosymbiotic mixotrophy: symbioses, filter-feeding, and the retention of a complete gut are observed simultaneously. Interspecific and habitat differences are discussed in the context of both species’ evident evolutionary success in adapting to ephemeral, chemically reduced habitats in the deep sea.

The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.

Certain aspects of the population dynamics of the brown mussel, Perna perna, were examined at 18 sites along the south coast of South African. Specifically the effects of wave exposure and tidal height were examined in relation to mussel size, biomass and density. A single set of samples was removed from each of the 18 sites, over three spring tide cycles. Sites were classified as exposed or sheltered prior to sampling. Principal component analysis (PCA) (based on mussel length data) and length frequency histograms revealed that there was a general decrease in the modal size of the adult mussel cohort with an increase in tidal height. The effects of exposure on mussel size decreased higher on the shore. On the exposed low shore the maximum size of mussels had a mean length of 102.3mm and was significantly larger (ANOVA, p<0.0001) than that for mussels on sheltered shores (86.7mm). The difference between mean maximum lengths of mussels on the mid shore was not so great, exposed sites had a average mean maximum length of 79.9, while on the sheltered shores it was 68.4mm. On the high shore the difference between the average mean maximum lengths at exposed and sheltered sites was only 3.9mm. The fact that the effects of exposure were greatest on the low shore was also borne out in the PCA. In this analysis low shore exposed and sheltered zones separated into two groups with little overlap, mid shore exposed and sheltered zones were positioned next to each other, and exposed and sheltered high shore zones were clumped together. Densities of adult mussels (>l5mm) were calculated as real densities from randomly placed quads i.e. not from areas of 100% cover. Density decreased up the shore; low, mid and high shore zones were significantly different from each other (ANOVA , p<0.0001; followed by multiple range tests). There was no significant difference between the densities of mussels at exposed and sheltered sites within each zone (ANOVA, p=0.7155). Recruit (<l5mm) densities increased with an increase in adult mussel densities, and this relationship was significant at all zones and for both degrees of exposure (regression analysis, p<0.05 in all cases). The regression between recruits and adults was strongest on the mid and high shore exposed sites. There was a general trend towards stronger regressions and greater predictability with an increase in shore height. The presence of free space within the mussel beds and significant regressions between recruit and adult densities indicates that mussel populations are recruit limited. Mean biomass decreased with an increase in shore height and was probably related to the decrease in size and density of mussels at higher shore levels. Exposure did not affect the average biomass within each zone. A fine scale study of the effects of wave exposure, tidal height and substratum type on recruit densities was undertaken at two sites, viz. Diaz Cross and High Rocks. Two shores, one exposed and one sheltered were identified at each of the sites. All shores were classified prior to sampling. Sampling was completed over a 30 day period during peak recruitment, and samples were removed on as many days as sea and tide conditions permitted i.e. daily when possible. The total density of early plantigrades was greater at Diaz Cross than it was at the High Rocks, and this may be related to the local hydrodynamic patterns adjacent to the two sites. Exposure affected the densities of early and late plantigrades on algae on the low shore sites, where greater numbers of recruits were recorded on exposed low shore zones. Densities of plantigrades on the mussel bed and on algae on the mid and high shore were not affected by exposure. Low and mid shore zones usually had greater densities (at 100% cover of substratum) of plantigrades than the high shore zones, this was probably related to lower settlement rates on the high shore as a result of reduced submergence time. Generally greater plantigrade densities were recorded on algal substrata than on the mussel bed. In only one of the 20 comparisons completed was the density of plantigrades greater on mussels than it was on algae. However when the area of the substratum within a zone was taken into account the number of plantigrades in the mussel bed at a zone was often greater than the number on algae within the same zone. In close to half of these comparisons the total numbers of plantigrades were greater on the mussels than on the algae. This was due to the greater area of mussel bed available to recruits. There was no evidence supporting the suggestion of secondary settlement of plantigrades from algae to the mussel bed. The results of this study demonstrate the importance of wave exposure, tidal height and substratum on certain aspects of the ecology of Perna perna. The importance of these factors is demonstrated at both the adult and early recruit stages of this mussel.

The general aim of this thesis was to examine the merits of ex-situ vs. in-situ strategies for the conservation of the endangered freshwater pearl mussel, Margaritifera margaritifera, and to investigate the relationship of the larval parasitic stages of the mussel (glochidia) with the salmonid hosts. To this end, I critically reviewed the literature on conservation of freshwater mussels, developed methods for quantifying the behaviour and activity patterns of adult mussels in captivity, experimentally studied host specificity, and quantified the physiological and behavioural effects of glochidia upon salmonid hosts. The results indicate that the conservation of the freshwater pearl mussel is probably best addressed at the watershed scale, and will benefit from a combination of ex-situ and in-situ techniques, as well as from a more critical assessment of findings, many of which are only reported in the grey literature. Empirical, peer-reviewed data are badly needed to inform current conservation efforts. Novel Hall-effect magnetic sensors were used to quantify and characterise discrete mussel behaviours without adversely affecting the welfare or survival of adult mussels, and these hold considerable potential for determining optimal rearing conditions for ex-situ conservation. Arctic charr was shown to be a potentially suitable host for M. margaritifera, and occupied an intermediate position in host suitability between brown trout and Atlantic salmon. Physiological impacts of glochidia upon brown trout included swelling of secondary lamellae and spleen enlargement, but the latter tended to be slight and was restricted to 1 month post-exposure. Glochidia encystment had no significant effect on blood haematocrit, respiratory performance, or cryptic colouration of brown trout hosts. The behavioural effects were more subtle and glochidiosis made brown trout more risk-averse and less willing to explore a novel habitat, without affecting the host's ability to chemically recognise and avoid cues from a predator. Overall, the results of this thesis indicate that the impacts of glochidia upon salmonid hosts are probably slight and temporally variable, and may perhaps lead to increased host survival, which would support the symbiosis-protocooperation theory of glochidia-salmonid interaction.