Kommentar zum Worm-et-al.-Artikel„Impacts of Biodiversity Loss on Ocean Ecosystem Services“: erschienen im Wissenschaftsmagazin Science, Vol. 314, am 3. November 2006

Folgende Kernbehauptungen bzw. Hypothesen werden in dem Worm-et-al.-Artikel aufgestellt: -Der Verlust an Biodiversität (Artenzahl) in einem Meeresgebiet reduziert tief greifend seine Produktivität und seine Stabilität in Stressperioden, hervorgerufen u.a. durch Überfischung und Klimaänderung. -Die Zahl der kollabierten Arten nimmt zu. Dieser Trend projeziert den Kollaps aller wildlebenden Arten und Bestände, die gegenwärtig befischt werden, auf das Jahr 2048. -Diese Entwicklung ist zum gegenwärtigen Zeitpunkt reversibel, denn das Meer besitzt noch ein großes Potential sich zu regenerieren. Dazu ist aber mehr Umweltschutz notwendig.

Biodiversity Loss in the Ocean: How Bad Is It?

MURAWSKI AND COLLEAGUES STATE THAT OUR assessment of the impacts of global marine biodiversity loss is overly pessimistic. They imply that management interventions are likely to reverse current trends of overfishing, and that the U.S. National Marine Fisheries Service (NMFS) has already met that goal. They cite Georges Bank haddock as an example and contest that catch metrics (as used in our global analysis) are sufficient to track the status of this particular fish stock and possibly others. We agree that precise biomass data are preferable, but these are rarely available. Here, we illustrate that catches are a good proxy of the status of haddock, although there can be a short delay in detecting recovery under intense management. While NMFS’s own data show that full recovery is still uncommon (<5% of overfished stocks) (1), we strongly agree that destructive trends can be turned around and that rebuilding efforts need to be intensified to meet that goal. But we must not miss the forest for the trees: Continuing focus on single, well-assessed, economically viable species will leave most of the ocean’s declining biodiversity under the radar.

Response to Comments on "Impacts of Biodiversity Loss on Ocean Ecosystem Services"

We show that globally declining fisheries catch trends cannot be explained by random processes and are consistent with declining stock abundance trends. Future projections are inherently uncertain but may provide a benchmark against which to assess the effectiveness of conservation measures. Marine reserves and fisheries closures are among those measures and can be equally effective in tropical and temperate areas—but must be combined with catch-, effort-, and gear restrictions to meet global conservation objectives.

Biodiversity loss and ecosystem functioning: Distinguishing between number and identity of species

Given currently high rates of extinction, it is critical to be able to predict how ecosystems will respond to loss of species and consequent changes in community structure. Much previous research in this area has been based on terrestrial systems, using synthetically assembled communities. There has beer! much less research on inter-trophic effects in different systems, using in situ removal experiments. Problems with the design of early experiments have made it difficult to determine whether reductions in ecosystem functioning in low diversity treatments were due to the number of species present or merely to the reduced likelihood of including particular (

Impact of biodiversity loss on production in complex marine food webs mitigated by prey-release

Public concern over biodiversity loss is often rationalized as a threat to ecosystem functioning, but biodiversity-ecosystem functioning (BEF) relations are hard to empirically quantify at large scales. We use a realistic marine food-web model, resolving species over five trophic levels, to study how total fish production changes with species richness. This complex model predicts that BEF relations, on average, follow simple Michaelis-Menten curves when species are randomly deleted. These are shaped mainly by release of fish from predation, rather than the release from competition expected from simpler communities. Ordering species deletions by decreasing body mass or trophic level, representing 'fishing down the food web', accentuates prey-release effects and results in unimodal relationships. In contrast, simultaneous unselective harvesting diminishes these effects and produces an almost linear BEF relation, with maximum multispecies fisheries yield at approximate to 40% of initial species richness. These findings have important implications for the valuation of marine biodiversity.

Declining resilience of ecosystem functions under biodiversity loss

The composition of species communities is changing rapidly through drivers such as habitat loss and climate change, with potentially serious consequences for the resilience of ecosystem functions on which humans depend. To assess such changes in resilience, we analyse trends in the frequency of species in Great Britain that provide key ecosystem functions-specifically decomposition, carbon sequestration, pollination, pest control and cultural values. For 4,424 species over four decades, there have been significant net declines among animal species that provide pollination, pest control and cultural values. Groups providing decomposition and carbon sequestration remain relatively stable, as fewer species are in decline and these are offset by large numbers of new arrivals into Great Britain. While there is general concern about degradation of a wide range of ecosystem functions, our results suggest actions should focus on particular functions for which there is evidence of substantial erosion of their resilience.

Invasive predators and global biodiversity loss.

Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global metaanalysis of these impacts and reveal their full extent. Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions-58% of these groups' contemporary extinctions worldwide. These figures are likely underestimated because 23 critically endangered species that we assessed are classed as "possibly extinct." Invasive mammalian predators endanger a further 596 species at risk of extinction, with cats, rodents, dogs, and pigs threatening the most species overall. Species most at risk from predators have high evolutionary distinctiveness and inhabit insular environments. Invasive mammalian predators are therefore important drivers of irreversible loss of phylogenetic diversity worldwide. That most impacted species are insular indicates that management of invasive predators on islands should be a global conservation priority. Understanding and mitigating the impact of invasive mammalian predators is essential for reducing the rate of global biodiversity loss.

Land use intensification alters ecosystem multifunctionality via loss of biodiversity and changes to functional composition

Global change, especially land-use intensification, affects human well-being by impacting the deliv-ery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is amajor component of global change effects on multifunctionality in real-world ecosystems, as inexperimental ones, remains unclear. Therefore, we assessed biodiversity, functional compositionand 14 ecosystem services on 150 agricultural grasslands differing in land-use intensity. We alsointroduce five multifunctionality measures in which ecosystem services were weighted according torealistic land-use objectives. We found that indirect land-use effects, i.e. those mediated by biodi-versity loss and by changes to functional composition, were as strong as direct effects on average.Their strength varied with land-use objectives and regional context. Biodiversity loss explainedindirect effects in a region of intermediate productivity and was most damaging when land-useobjectives favoured supporting and cultural services. In contrast, functional composition shifts,towards fast-growing plant species, strongly increased provisioning services in more inherentlyunproductive grasslands.

Biodiversity offsetting and restoration under the European Union Habitats Directive: balancing between no net loss and deathbed conservation?

Biodiversity offsets have emerged as one of the most prominent policy approaches to align economic development with nature protection across many jurisdictions, including the European Union. Given the increased level of scrutiny that needs to be applied when authorizing economic developments near protected Natura 2000 sites, the incorporation of onsite biodiversity offsets in project design has grown increasingly popular in some member states, such as the Netherlands and Belgium. Under this approach, the negative effects of developments are outbalanced by restoration programs that are functionally linked to the infrastructure projects. However, although taking into consideration that the positive effects of onsite restoration measures leads to more leeway for harmful project development, the EU Court of Justice has recently dismissed the latter approaches for going against the preventative underpinnings of the EU Habitats Directive. Also, the expected beneficial outcomes of the restoration efforts are uncertain and thus cannot be relied upon in an ecological assessment under Article 6(3) of the Habitats Directive. Although biodiversity offsets can still be relied upon whenever application is being made of the derogation clause under Article 6(4) of the Habitats Directive, they cannot be used as mitigation under the generic decision-making process for plans and programs liable to adversely affect Natura 2000 sites. We outline the main arguments pro and contra the stance of the EU Court of Justice with regards to the exact delineation between mitigation and compensation. The analysis is also framed in the ongoing debate on the effectiveness of the EU nature directives. Although ostensibly rigid, it is argued that the recent case-law developments are in line with the main principles underpinning biodiversity offsetting. Opening the door for biodiversity offsetting under the Habitats Directive will certainly not reverse the predicament of the EU’s biodiversity. A reinforcement of the preventative approach is instrumental to avert a further biodiversity loss within the European Union, even if it will lead to additional permit refusals for unsustainable project developments.

Contributions of the private sector to global biodiversity protection: case study of the Fortune 500 companies

Since the inception of the UN Convention on Biological Diversity (CBD) in 1992, little progress has been achieved in terms of involving the business community in protecting biological diversity worldwide. This article assesses the current activities of US Fortune 500 companies with respect to global biodiversity protection and the goals of the CBD. Data and information collected from 500 companies within eight major industrial sectors were further categorized at the company level to assess each company's involvement in global biodiversity protection. Our findings show that although companies' business profiles highly influence their decision-making process regarding the adoption of biodiversity protection policies and measures, their revenue profiles are less influential. We show that despite generating low revenues, companies in the utility sector are more active in the adoption of biodiversity protection policy than those in the financial sector, which generate high revenues. This study also demonstrates that companies must be convinced of the major effects of biodiversity loss on their bottom lines to be motivated to protect biological diversity. Companies' business and business-related risk profiles can also influence the adoption of biodiversity protection policies within the company. The study further demonstrates that a measurable biodiversity impact indicator is necessary for the companies to get seriously involved in the mitigation action. Finally, this study proposes a three-step biodiversity loss mitigation action framework that is drawn upon the assessment of the 500 companies that can contribute to develop an elaborative framework of business sector-specific mitigation plan. © 2013 Copyright Taylor and Francis Group, LLC.