Zooplankton grazing on Phaeocystis: A quantitative review and future challenges

The worldwide colony-forming haptophyte phytoplankton Phaeocystis spp. are key organisms in trophic and biogeochemical processes in the ocean. Many organisms from protists to fish ingest cells and/or colonies of Phaeocystis. Reports on specific mortality of Phaeocystis in natural plankton or mixed prey due to grazing by zooplankton, especially protozooplankton, are still limited. Reported feeding rates vary widely for both crustaceans and protists feeding on even the same Phaeocystis types and sizes. Quantitative analysis of available data showed that: (1) laboratory-derived crustacean grazing rates on monocultures of Phaeocystis may have been overestimated compared to feeding in natural plankton communities, and should be treated with caution; (2) formation of colonies by P. globosa appeared to reduce predation by small copepods (e.g., Acartia, Pseudocalanus, Temora and Centropages), whereas large copepods (e.g., Calanus spp.) were able to feed on colonies of Phaeocystis pouchetii; (3) physiological differences between different growth states, species, strains, cell types, and laboratory culture versus natural assemblages may explain most of the variations in reported feeding rates; (4) chemical signaling between predator and prey may be a major factor controlling grazing on Phaeocystis; (5) it is unclear to what extent different zooplankton, especially protozooplankton, feed on the different life forms of Phaeocystis in situ. To better understand the mechanisms controlling zooplankton grazing in situ, future studies should aim at quantifying specific feeding rates on different Phaeocystis species, strains, cell types, prey sizes and growth states, and account for chemical signaling between the predator and prey. Recently developed molecular tools are promising approaches to achieve this goal in the future. © 2007 Springer Science+Business Media B.V

Transcending sovereignty : locating Indigenous peoples in transboundary water law

All people rely upon water for life. Indigenous peoples are especially vulnerable to water conflicts and yet lack recognition in international water law. This thesis adopts Critical Race Theory to examine the intersection between transboundary water law, the doctrine of sovereignty and the international law of Indigenous peoples. The methodology adopted in this thesis includes: (i) a deconstruction of the UN Watercourse Convention and the doctrine of sovereignty; (ii) a review of Indigenous perspectives on sovereignty; and (iii) a proposal for the reconstruction of transboundary water law in a manner that recognizes the internationally affirmed rights of Indigenous peoples. A deconstruction of the UN Watercourse Convention and related discourse reveals that state-centric approaches to transboundary water law fail to recognize Indigenous peoples’ international rights or the pivotal role that Indigenous peoples’ traditional knowledge might play in transcending conflict. Case examples are provided (Columbia River and Tsangpo-Brahmaputra River) that illustrate the vulnerability of Indigenous peoples in the face of state development agreements. The inequities that exist in international water law are rooted in the historical doctrine of sovereignty which has evolved to subordinate Indigenous peoples’ interests to state interests. Indigenous perspectives regarding sovereignty provide a counter-point to the dominant legal discourse and weave an alternate narrative that challenges the myth of objectivity and neutrality that surrounds the doctrine of sovereignty and international law generally. Once we recognize that sovereignty is a social construct, we can recognize our collective ability to reconstruct international laws in a manner that transcends the sovereign discourse and recognizes the rights of Indigenous peoples. Endorsement of the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP) is indicative of states’ commitment to recognize Indigenous peoples’ rights throughout the international legal system. This thesis concludes by offering a proposal for reconstructing transboundary water law through a return to ethics and coalition building. Future reform should be directed towards (a) articulating an international water ethic with the critical engagement of Indigenous peoples; and (b) ensuring that river basin organizations are established on every transboundary river in a manner consistent with this shared international water ethic.Law, Faculty ofGraduat