More information on Plenary session will be added soon.
Gerard P. Closs
Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand.
Date to be added soon.
Larvae and Landscape: Life history, migration and dispersal in diadromous fish
Most species of fish, be they marine or freshwater, have small pelagic larvae. In species with a benthic adult life history stage, these benthic-pelagic life history migrations are well recognised from both marine and freshwater systems. Somewhat paradoxically, and despite the success of this life history strategy, tiny pelagic larvae are fragile, often dying en masse when confronted by harsh conditions. So why do so many fish exploit this apparently vulnerable life history strategy. The answer to this paradox appears to be fecundity – tiny eggs and larvae that when reared in a suitably productive and benign pelagic environment, generates prodigious recruitment back into adult habitat. Such reproductive success can facilitate the dominance of these highly fecund species in and around marine and freshwater pelagic environments. However, when this life history strategy is unavailable, less fecund life histories can persist, with large robust larvae required to survive challenging larval rearing conditions.
Diadromous migrations in freshwater fish species – specifically amphidromy and catadromy – can be viewed as strategies for getting large numbers of larvae into pelagic rearing environments, and so gaining the fecundity advantage that comes from producing tiny eggs and larvae. The distribution of the two apparently different life histories can be understood as a response to the challenge of transporting fragile larvae from adult habitats to a pelagic rearing habitat across varying aquatic landscapes and hydrological environments. Multiple non-migratory freshwater species have also evolved from diadromous species across the Indo-Pacific. However, the evolution of a non-migratory freshwater life history strategy often comes at the cost of fecundity, as such species often require larger robust larvae to survive in unproductive headwater stream environments. Thus, the distribution of freshwater fish species and associated life history strategies across the insular freshwater ecosystems of the Indo-Pacific can be seen as a response to landscape. In particular, amphidromous and catadromous life histories can best be understood as benthic-pelagic larval migrations writ large across the landscape, with non-migratory low fecundity species possessing larval traits that facilitate survival in harsh, often unproductive, riverine habitats. In this presentation, I review and discuss evidence for this larval-centric view of freshwater fish life history across the Indo-Pacific, with a focus on recent work on New Zealand systems.
National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan
Date to be added soon.
BLEEKER AWARD (Systematic) / The Kuroshio Current, an invisible barrier to shallow-water fishes of southern Japan
The Kuroshio Current flows in the West Pacific from the eastern side of the Philippines into the East China Sea between Taiwan and the southern tip of the Ryukyu Islands. It continues northward in the East China Sea along the Ryukyu Islands before returning to the West Pacific through the Tokara Strait in the northern part of the Ryukyu Islands. The Kuroshio Current washes the Pacific coasts of the main islands of Japan and turns eastward around the central part of Honshu Island eventually reaching the Hawaiian Islands. The Kuroshio is a very strong current flowing at a rate of about 3 knots and conveying 30 to 50 million tons of seawater per second. This strong, warm current transports many marine organisms including larval, juvenile and adult fishes from south to north and strongly influences the fish fauna of southern Japan.
In 2008 I organized a team of Japanese ichthyologists to study the fish fauna of southern Japan. The team intensively sampled shallow-water fishes in 12 locations along the Pacific coast of Honshu, Shikoku and Kyushu islands, and the Ogasawara and Ryukyu Islands. In addition to field surveys, the compositions of fish species at the 12 locations were analyzed using data in a huge Fish Image Database comprising 100,000 photographs of fishes. The faunal analyses of the 12 locations clearly revealed two assemblages of fish fauna in Japan: one inhabiting the main islands and the Ogasawara Islands located 1000 km south of Tokyo, and the other distributed in the Ryukyu Islands. The results strongly suggest that the Kuroshio Current plays an important role not only in transporting coral-reef fishes from south to north but also forms an invisible barrier for temperate fishes when they move south toward the Ryukyu Islands. The long-term surveys of fishes in the Kuroshio Current have also resulted in the discovery of many new species including a new pufferfish that constructs an amazing and elaborate circular spawning site on the sea floor.
College of Science and Engineering & ARC Centre of Excellence for Coral Reef Studies James Cook University, AUSTRALIA
Date to be added soon.
BLEEKER AWARD (Ecology) / Why fishes matter
Pieter Bleeker was one of the early pioneers of fish research. His primary goal was to identify the fishes that were present on the reefs of Indonesia. He worked in an era before the term ecology arose; what these fishes were doing was a question for the future. Today, what fishes do is critical. It is now widely accepted that it is the ecology of fishes, and more specifically their functional roles, that are important for the survival of aquatic ecosystems. In this talk I will explore the roles of fishes and how they have shaped our understanding of the world. Like Bleeker, my focus will be on coral reefs, for it is in these ecosystems that fishes have had perhaps the greatest impact. Fishes have shaped reefs for over 300 million years although the extent of their influence has increased markedly over time; from nibbling attached prey on early reefs to modern reefs where they dominate trophic interactions, determine benthic community composition, and even the structure and form of the reef itself. Today fishes influence almost every major ecological process on coral reefs from nutrient transfer to bioerosion. They are also the primary resource harvested by humans. They therefore have been the focus of much attention, being both fascinating and important. However, I believe their greatest contribution will be the role they play in shaping our future. For most of the last century, the functional operations of reef systems have been heavily influenced by fishing activity. As a consequence, we have responded with management approaches that protect biodiversity or exploited stocks (MPAs). However, our ability to identify, protect, maintain or restore critical ecosystem functions is still in its infancy. This inability has exposed our limitations. The global loss of corals has resulted in coral reef ecosystems that are fundamentally different to anything we have encountered before. It is in this future world that fishes will again lead the way. We have to recognize that coral reefs of the future are again going to be shaped by fishes and if we are going to steer reefs through the Anthropocene fishes are going to be our most important guides.