Dispersal of Hormosira banksii (phaeophyceae) via detached fragments : reproductive viability and longevity

Drifting, fertile thalli are well documented to be the primary long-distance dispersal vector for many marine macroalgae, but little information about reproductive viability of drift is known. This study examined the reproductive viability and longevity of floating fragments of the intertidal Australasian fucoid Hormosira banksii (Turner) Decne. Beach wrack surveys and field experiments were conducted to test the model that long-distance dispersal is achieved in H. banksii via floating, fertile fronds. High densities of beach wrack fragments were evident during summer compared to autumn. The majority of beach wrack occurred on sandy beaches rather than rocky shores. Both male and female fragments were present in the beach wrack. Detached fronds were capable of releasing gametes up to 8 weeks after detachment. Beach wrack produced high fertilization rates and recruited successfully onto artificial panels. Results suggest that detached fragments are reproductively viable and that floating, fertile fronds may be an important mechanism for facilitating long-distance dispersal in this species. Nevertheless, the frequency of fronds reaching a suitable habitat and contributing to gene flow between populations, or colonizing new populations, may not be proportional to the total density of beach wrack.

Dislodgment and attachment strength of the intertidal macroalga Hormosira banksii (Fucales, Phaeophyceae)

Hormosira banksii is a dominant intertidal alga characterised by limited dispersal of propagules, yet it has a broad distribution throughout temperate Australasia. However, the high abundance of beach wrack of H. banksii on sandy beaches along southwest Victoria, the frequency of frond dislodgment and the force required to break it from the substratum remain unknown. Dislodgment of macroalgae has been shown to influence dispersal processes; therefore, we tested the model that long-distance dispersal of H. banksii is facilitated by weak attachment to the substratum and frequent dislodgment of fertile fronds. We monitored the dislodgment of H. banksii individuals and conducted in situ pull tests to determine the attachment strength of fronds of H. banksii. We further tested whether thallus size or pull direction influenced attachment strength of H. banksii. We found that breakage of vesicles and fronds was a regular event during the survey period and that the mean attachment strength of fronds of H. banksii was weak compared to other intertidal algae. Furthermore, we found that thallus size did not influence the force required to break fronds of H.banksii from the substratum but that the direction that fronds were pulled from the substratum did. We suggest that fronds of H. banksii do drift frequently and that long-distance dispersal is likely to be an important mechanism for the distributional success of this species.

Potential for long-distance dispersal of Hormosira banksii

This study examined the potential for long-distance dispersal via drifting fertile fronds of the brown seaweed, Hormosira banksii. Results suggest that H. banksii may have dual dispersal capabilities (e.g. propagules and drifting fronds), which may maintain the broad distribution of this species.

Restoration of the habitat-forming fucoid alga Hormosira banksii at effluent-affected sites : competitive exclusion by coralline turfs

Fucoid algae often dominate intertidal rocky shores, providing habitat and modifying ecosystem resources for other species, but are susceptible to discharge of sewage effluent. In this study we assessed the potential for competition from coralline turfs to inhibit restoration of the intertidal fucoid macroalga Hormosira banksii at sites associated with an ocean outfall a scenario of improving following water quality in the nearshore coastal environment. The percentage cover and number of individuals of H. banksii were negatively correlated with both the percentage cover and turf height of Corallina officinalis. In contrast, H. banksii was positively associated with rocky substrata and recruited well to rock-surface substrata. Importantly, there appears to be a threshold abundance where the percentage cover of H. banksii rarely reaches above 20% cover amongst coralline turfs with >40% cover. These data support a model of alternative community states: H. banksii dominated canopy on rocky substrata versus C. officinalis turf. In field and laboratory experiments, extensive coralline turfs (up to 4 cm thick) were shown to inhibit recruitment of H. banksii. This study shows competitive exclusion by coralline turfs may limit the successful restoration of habitat provided by H. banksii to shores that have been affected by sustained discharge of secondarily treated sewage effluent. We suggest potential strategies for management authorities to consider when seeking ways of restoring fucoid communities affected by anthropogenic disturbances such as wastewater disposal.

Functionalism, co-operation, good faith, and the making of the "daily-preventive justice" in contract law theory and practice. A contribution to a rational understanding of good faith and to its future reseasonable developments. Evaluations from

The thoughts and observations contained in this paper were first presented in a preliminary form at the Staff Seminar that I gave at the University of Cape Town (UCT) - Department of Private Law, on Tuesday May 8 2012. The organizers generously offered me a free choice of subject. Such an offer always poses a problem to imaginative people like myself. I finally chose as my subject the role of good faith in contract law theory and practice and then entitled the Seminar “Good Faith & Contracts - Brothers in Arms”. The aim of the talk was to briefly describe what I see behind the doctrine of good faith (and, more broadly, behind the general course of the parties’ behavior before and after the conclusion of an agreement), to then explain the need of its protection and future reasonable developments by challenging the limitations of both traditional and current legal approaches to contract law theory and practice. By adopting a comparative modus investigandi, it emerged that especially in the area of contract law a new law-finding process is emerging in the European continent and it is leading to re-conceive the meta-national legislative interventions by challenging the limits of Hobbes’s Leviathan. As asserted, we ought to not take this process for granted because although there are many forms of social organization, contract is the most pervasive and the law of contract still is the most important vehicle to support and supplement private arrangements. However, the point of departure for theorizing about private law is based on experience. Consequently, despite the growing emphasis on the convergence of national legal systems in Europe, conducting research on private law theory and practice requires that imagination and creativity be matched with prudence. Proficiency has to be aligned with what we have learned from history.