Showing papers on "Aquatic biodiversity research published in 2006"

Biodiversity and the functioning of seagrass ecosystems

Abstract: Biodiversity at multiple levels — genotypes within species, species within functional groups, habitats within a landscape — enhances productivity, resource use, and stability of seagrass ecosystems. Several themes emerge from a review of the mostly indirect evidence and the few exper- iments that explicitly manipulated diversity in seagrass systems. First, because many seagrass com- munities are dominated by 1 or a few plant species, genetic and phenotypic diversity within such foundation species has important influences on ecosystem productivity and stability. Second, in sea- grass beds and many other aquatic systems, consumer control is strong, extinction is biased toward large body size and high trophic levels, and thus human impacts are often mediated by interactions of changing 'vertical diversity' (food chain length) with changing 'horizontal diversity' (heterogene- ity within trophic levels). Third, the openness of marine systems means that ecosystem structure and processes often depend on interactions among habitats within a landscape (landscape diversity). There is clear evidence from seagrass systems that advection of resources and active movement of consumers among adjacent habitats influence nutrient fluxes, trophic transfer, fishery production, and species diversity. Future investigations of biodiversity effects on processes within seagrass and other aquatic ecosystems would benefit from broadening the concept of biodiversity to encompass the hierarchy of genetic through landscape diversity, focusing on links between diversity and trophic interactions, and on links between regional diversity, local diversity, and ecosystem processes. Maintaining biodiversity and biocomplexity of seagrass and other coastal ecosystems has important conservation and management implications.

Global marine biodiversity trends

Abstract: ■ Abstract Marine biodiversity encompasses all levels of complexity of life in the sea, from within species to across ecosystems. At all levels, marine biodiversity has naturally exhibited a general, slow trajectory of increase, punctuated by mass extinctions at the evolutionary scale and by disturbances at the ecological scale. In historical times, a synergy of human threats, including overfishing, global warming, biological

Biodiversity loss and the taxonomic bottleneck: emerging biodiversity science

Abstract: Human domination of the Earth has resulted in dramatic changes to global and local patterns of biodiversity. Biodiversity is critical to human sustainability because it drives the ecosystem services that provide the core of our life-support system. As we, the human species, are the primary factor leading to the decline in biodiversity, we need detailed information about the biodiversity and species composition of specific locations in order to understand how different species contribute to ecosystem services and how humans can sustainably conserve and manage biodiversity. Taxonomy and ecology, two fundamental sciences that generate the knowledge about biodiversity, are associated with a number of limitations that prevent them from providing the information needed to fully understand the relevance of biodiversity in its entirety for human sustainability: (1) biodiversity conservation strategies that tend to be overly focused on research and policy on a global scale with little impact on local biodiversity; (2) the small knowledge base of extant global biodiversity; (3) a lack of much-needed site-specific data on the species composition of communities in human-dominated landscapes, which hinders ecosystem management and biodiversity conservation; (4) biodiversity studies with a lack of taxonomic precision; (5) a lack of taxonomic expertise and trained taxonomists; (6) a taxonomic bottleneck in biodiversity inventory and assessment; and (7) neglect of taxonomic resources and a lack of taxonomic service infrastructure for biodiversity science. These limitations are directly related to contemporary trends in research, conservation strategies, environmental stewardship, environmental education, sustainable development, and local site-specific conservation. Today’s biological knowledge is built on the known global biodiversity, which represents barely 20% of what is currently extant (commonly accepted estimate of 10 million species) on planet Earth. Much remains unexplored and unknown, particularly in hotspots regions of Africa, South Eastern Asia, and South and Central America, including many developing or underdeveloped countries, where localized biodiversity is scarcely studied or described. "Backyard biodiversity", defined as local biodiversity near human habitation, refers to the natural resources and capital for ecosystem services at the grassroots level, which urgently needs to be explored, documented, and conserved as it is the backbone of sustainable economic development in these countries. Beginning with early identification and documentation of local flora and fauna, taxonomy has documented global biodiversity and natural history based on the collection of "backyard biodiversity" specimens worldwide. However, this branch of science suffered a continuous decline in the latter half of the twentieth century, and has now reached a point of potential demise. At present there are very few professional taxonomists and trained local parataxonomists worldwide, while the need for, and demands on, taxonomic services by conservation and resource management communities are rapidly increasing. Systematic collections, the material basis of biodiversity information, have been neglected and abandoned, particularly at institutions of higher learning. Considering the rapid increase in the human population and urbanization, human sustainability requires new conceptual and practical approaches to refocusing and energizing the study of the biodiversity that is the core of natural resources for sustainable development and biotic capital for sustaining our life-support system. In this paper we aim to document and extrapolate the essence of biodiversity, discuss the state and nature of taxonomic demise, the trends of recent biodiversity studies, and suggest reasonable approaches to a biodiversity science to facilitate the expansion of global biodiversity knowledge and to create useful data on backyard biodiversity worldwide towards human sustainability.

Diversity without representation

Abstract: For policymakers, biodiversity can present more complex challenges than climate change, argue Michel Loreau, Alfred Oteng-Yeboah and their co-authors. So why isn't there an international panel of experts for biodiversity?

Respiration in Aquatic Ecosystems

Abstract: What does our future depend on? On many things, certainly, but on a global scale, and from an ecological point of view, the change in the partial pressure of carbon dioxide in the atmosphere could play a major role, together with the resulting change in the Earth’s temperature. Oxygen is another story, but current thoughts suggest that the oceans contribute roughly a third of the production of molecular oxygen on our planet. In both cases, the respiratory activity in the seas and oceans plays a fundamental role through the carbon cycle.

Soil Biodiversity in Amazonian and Other Brazilian Ecosystems

Abstract: This book reviews soil biodiversity and related ecological processes in one of the key biodiversity hotspots of the world, the Amazon, and nearby regions of Brazil. It covers both the tropical savannah and rainforests. Chapters describe the biology, ecology, taxonomy, geographic distribution and sampling methods for the most important soil functional groups.

Marine biodiversity and ecosystem function: empirical approaches and future research needs

Abstract: The functioning of the global ecosystem is mediated in large part by pelagic marine organisms through their influence on biomass production, elemental cycling, and atmospheric composition. Growing theoretical and empirical evidence suggests that the stability and functioning of this complex system may depend, not only on aggregate biomass and production of pelagic producers and consumers, but also on the composition and richness of taxa within those compartments. Yet rigorous experimental tests of relationships between diversity and these aspects of pelagic ecosystem functioning are virtually unknown. Here, we argue for more attention to such research, and we marshal preliminary evidence that several mechanisms underlying diversity effects on ecosystem processes in marine benthic and terrestrial systems also may operate in pelagic systems. We review selected examples of how genetic, species, and functional group diversity may affect ocean ecosystem processes. We consider 3 types of examples that detail how (1) producer richness or composition can directly affect ecosystem processes, (2) consumer diversity can directly and indirectly affect these same processes, and (3) diversity at and below the species level can reduce variation of communities through time and enhance their resistance to perturbations. We suggest several promising avenues for assessing the role of biodiversity in pelagic ecosystems. Understanding and predicting responses of the global ocean ecosystem to accelerating climate and environmental change will be enhanced by more explicit and systematic attention to the functional diversity of microbial and macroscopic marine life.

Expanding scales in biodiversity-based research: challenges and solutions for marine systems

Abstract: As in terrestrial biodiversity, human influences over marine biodiversity will alter the way ecosystems contribute to biogeochemical or ecosystem processes. While many studies have doc- umented how alterations of terrestrial biology affect ecosystem functioning, few studies have exam- ined marine systems. The main challenge faced by biodiversity and ecosystem functioning (BEF) research in marine ecology is dealing with the large scales of marine systems and the logistical diffi- culties of attempting to conduct the kinds of complex, combinatorial experiments that have been done in terrestrial ecology. BioMERGE (Biotic Mechanisms of Ecosystem Regulation in the Global Environment) has developed a framework for relating biodiversity, via biomass, to ecosystem func- tioning and for employing extinction scenarios to explore the realm of possible changes in ecosystem functioning that biodiversity loss could create. This approach may find much utility in marine BEF research because it obviates the need for complex experiments. I provide an overview of the issues, the framework, and some directions marine ecology could take to further our understanding of the ecosystem consequences of marine biodiversity loss.

Biodiversity of freshwater microorganisms - achievements, problems, and perspectives

Abstract: The extent and significance of the diversity of freshwater microbes is at present controversially debated. Until 1980 it was assumed that there are no freshwater-specific bacteria and that the total number of bacterial species is low. The advent of molecular tools over the last ten years revealed that there is a bacterial freshwater assemblage which is phylogenetically different from soil and marine bacteria; secondly, it became obvious that the total number of cultured bacterial species (~5900) underestimates bacterial diversity by several orders of magnitude. The current debate centres on 1) how to define a bacterial species and 2) if there is a microbial biogeography. The latter relates to the issue of ubiquity and cosmopolitanism, which is controversially discussed primarily in relation to eukaryotic microorganisms, namely ciliates. Although solid evidence is scarce, many microbial ecologists assume, in accordance with Baas Becking’s famous 70-year old dictum – “everything is everywhere, the environment selects” – that freshwater microorganisms are easily dispersed and, therefore, potentially cosmopolitan. This review focuses on the often neglected second part of Baas Becking’s metaphor. Evidence is accumulating rapidly that the environment does not simply act as a filter sensu Gleason’s individualistic concept for widely dispersed microbes. Rather, prokaryotic and eukaryotic microorganisms have adapted to their specific habitat and perform better in this environment than newly invading congeners. There is an enormous ecophysiological diversity among closely related freshwater microbes which is neither obvious at the morphospecies level nor at the level of evolutionarily conserved genes, such as the small ribosomal RNA gene. Although this large diversity has been demonstrated for various groups of bacteria and protists, there is currently no measure available to compare microbial biodiversity across prokaryotic and eukaryotic domains. The current challenge is to link genetic divergence to ecophysiological diversity in the major taxa.

Biodiversity in European Shallow Lakes: a Multilevel-Multifactorial Field Study

Abstract: This chapter is based on the premise that the precipitous decline in freshwa- ter wetlands and species can only be arrested through conservation and sus- tainable management at a large scale, based on water (usually river) basins A number of approaches to large-scale freshwater wetlands conservation are presented and assessed to draw conclusions on future conservation priori- ties

Dutch domesticated Clarias with mixed genetic background now used in aquaculture in South Africa, with unpredictable consequences for biodiversity

Abstract: The sharptooth catfish, Clarias gariepinus (Burchell 1822), has a very wide distribution in Africa (Lévêque 1997). Cambray (2005) noted that, due to its possible aquaculture potential, this species was ‘leapfrogging’ around the world via the aquaculture pathway and was escaping into natural waters. This process is also happening in South Africa. Here, we trace the history of the Dutch domesticated strain of this species, and evaluate whether it should have been introduced into South Africa for aquaculture purposes. In 1976, some 40 Clarias gariepinus from Cameroon became the breeding nucleus cultured at the University of Wageningen, Holland, where the Dutch domesticated strain was bred (Verreth in litt. 2005), it having been selected for good shape (i.e. small head) and fast growth. When inbreeding symptoms were encountered in these fish, testes from Central African Republic and Nigerian males were used to bring in new genetic variety (Verreth in litt. 2005). In addition, Volckaert (pers. comm.) mentioned that the Dutch domesticated strain comprised a combination of various ‘aquaculture’ stocks from Israel and Central Africa (both regions being within the native range of this species). This strain was commercialised during the 1980s and is now produced in Holland, where annual production of 4 000 MT is achieved (Verreth in litt. 2005). It has also been exported to Hungary and to South Africa. The Dutch domesticated Clarias was identified as the preferred stock when the Megafisch recirculating system was adopted as a supposedly ideal intensive fish production technique for use in South Africa (J Theron pers. comm.). The first stocks were imported from Holland in 2001 (Beckert pers. comm. 2005, Kooij pers. comm. 2005). Initially, 40 adults were imported by Mr Johan Kooij, but later an additional 50 000 larvae were imported, forming the basis from which this strain was bred in South Africa. The importations were done under permits issued by the Department of Environmental Affairs and Tourism of the North West Province as well as by the national Department of Agriculture. In the closed recirculation systems in which they were kept, they showed very good growth rates, growing by between 1.8 and 3.5kg in eight months (J Kooij pers. comm.). However, problems were soon encountered. Whilst the imported fish could be bred every month, they produced few eggs and there was a low egg fertilisation rate. Low fertilities were subsequently overcome by back-crossing female domesticated fish with wild males obtained from the Crocodile River system, which also resulted in higher survival rates. Back-crossed fish were distributed by the assigned breeder, Mr J Kooij, to other Megafisch operations in South Africa, including those in Ventersdorp (Vaal River system), and Hazyview (Sabi River, Inkomati system) as well as at the following sites in the Limpopo system: Mabalingwe (Crocodile River) Delmas (Wilge River, Olifants Short Note

Molecular tools for the study of marine microbial diversity

Abstract: Marine photosynthetic microbial organisms are the major, sustaining components of ecosystem processes and are responsible for biogeochemical reactions that drive our climate changes. Despite this, many marine microorganisms are poorly described and little is known of broad spatial and temporal scale trends in their abundance and distribution. With new molecular and analytical techniques we can advance our knowledge of marine biodiversity at the species level to understand how marine biodiversity supports ecosystem structure, dynamics and resilience. We can then interpret environmental, ecological and evolutionary processes controlling and structuring marine ecosystem biodiversity. With better analytical methods available, we can augment our understanding of biodiversity and ecosystem dynamics in especially the pico- and nano-fractions of the plankton as well as in the deep sea benthos, both of which are very difficult to study. Here we provide examples of new and long standing molecular tools for researchers in marine ecosystems to enable them to provide better, faster and more accurate estimates of marine biodiversity in the community using tools at the forefront of molecular research.

Determinants of Biodiversity Change: Ecological Tools for Building Scenarios1

Abstract: As defined in the recent Millenium Ecosystem Assessment (MA), biodiversity scenarios are ‘‘plausible alternative futures.’’ They do not attempt to predict the precise future state of biodiversity, but rather they identify the consequences of the different paths that human society may follow for biodiversity. Scenarios are designed to assist decision makers by identifying costs and benefits, in terms of biodiversity, of alternative actions. Within the framework of the MA, the first stage in developing biodiversity scenarios was to identify the major drivers of biodiversity change in the next 50–100 years. Land-use change, climate change, and nutrient enrichment were identified as the major drivers of biodiversity change in terrestrial and freshwater ecosystems. The next steps in constructing successful biodiversity scenarios are (1) assessing changes in drivers of different socioeconomic scenarios and (2) developing the algorithms that relate changes in drivers with changes in biodiversity. This Special Feature focuses on a key component of the second of these two steps: evaluating the current tools used by ecologists to develop scenarios based on changes in drivers of biodiversity change. Land-use change has been recognized as the most important driver of biodiversity change in the current century. Models that simulate the interaction between economic and ecological systems estimate rates of deforestation and land-use change for different socioeconomic scenarios. However, not all species disappear as a result of land-use change. In this Special Feature, Pereira and Daily explore the question of how many species and which species can persist in modified landscapes. They used two different approaches, the classic species–area relationship and demographic models, focusing on the terrestrial mammal fauna of Central America. The approaches reported in the article by Pereira and Daily require information on species density in addition to data on land-use change. Biodiversity scenarios also need to start with a solid understanding of the current biodiversity patterns before human disturbance, but information on global patterns of current biodiversity is scarce. These data are generally available only for a few taxa, such as vascular plants, which have been a primary focus of taxonomic efforts. Volkmar Wolters et al. report on a study of the relationship among patterns of species density for different taxa and address the question of how valid it is to extrapolate from data based on the diversity of vascular plants to other taxa. Biodiversity scenarios should also explore the consequences for species richness of changes in drivers, such as land-use or climate change. Ibáñez et al. explore new approaches to assess the impacts of climate change and land-use change on biodiversity that go beyond the use of climate envelopes and species–area relationships. The authors suggest that extinctions are difficult to predict and to assess in the field. Their proposed alternative is to use variables that are related to biodiversity and that are diagnostic of extinction but that are more predictable than extinctions. Expected anthropogenic climate change will redistribute the locations where specific climatic conditions favorable to the survival of a species will occur. The effect of climate change on biodiversity loss is determined not only by the occurrence of climate conditions for survival, but also by the ability of individual species to migrate to the new location. Ibáñez et al. address the question of migration constraints and how these constraints may modulate the effect of climate change on biodiversity loss.

Marine Biodiversity Study and Biotechnology Exploitation in China

Abstract: Large scale marine biodiversity studies in China have been carried out for more than half a century since the founding of the Institute of Oceanology, CAS, in 1950. Through a series of coastal and multi-disciplinary oceanographic investigations in the shelf seas and biodiversity studies since the late fifties, a total of 20,278 species of marine biota have been recorded upto 1994. Recent intensive studies have further revealed the richness of marine biota of the China seas,a great number of marine species have been found and many new taxa established. The total species number of main biotic groups increased about 50 % of that estimated in 1994. The results have promoted the fast development of China's marine fisheries, medicine (drug) and biodiversity research, and attracted many scientists, particularly bio-technologists, to join their studies. Environmental deterioration and human activity strongly stressed the sustainable development and conservation of marine bio-diversity, and resulted in the increase of end angered species as record ed in the new published China Species Red List with the threatened category of species assessed by adopting the new IUCN criteria. To further reveal the high diversity and their history, present status and future of marine organisms existed in the world ocean, an international Project Census of Marine Life (CoML) was established in 2000 in the USA. Scientists predicted that 2 to 3 times of numbers of the known species will possibly be found in various marine habitats, particularly the abyssal ocean. The Research Plan and the Projects were briefly introduced, and the relationship between marine biodiversity and biotechnology was discussed. The Project planned to apply new and high techniques and new equipments on board research vessel and in laboratory. Brief review of recent advances of Chinas' marine biodiversity and biotechnology studies indicated that fascinate results have been achcieved; but further effort should be made to promote the continuous advance of our basic researches and their application in related production and maintain sustainable development.

Biodiversity, Science and Governance Workshop 10: 'Biodiversity: Challenges for Fisheries Management'

Abstract: The current status and trends in marine biodiversity were assessed, based on existing scientific knowledge. The considerable development of human uses of the oceans has severely altered marine biodiversity. The continued provision of goods and services derived from marine ecosystems is threatened by growing anthropogenic pressure and by the increasing risks of irreversible shifts due to global change. More marine species or populations than generally believed have undergone local, regional or global extinction. In addition, the consequences of human impacts on the poorly known components of marine biodiversity (in particular small organisms and microbes) remain unknown, despite the high role of these components in supporting ecosystem services.