Algemeen

During the 20 years from 1992 to 2011, pesticides were found at concentrations that exceeded aquatic-life benchmarks in many rivers and streams that drain agricultural, urban, and mixed-land use watersheds. Overall, the proportions of assessed streams with one or more pesticides that exceeded an aquatic-life benchmark were very similar between the two decades for agricultural (69% during 1992−2001 compared to 61% during 2002−2011) and mixed-land-use streams (45% compared to 46%). Urban streams, in contrast, increased from 53% during 1992−2011 to 90% during 2002−2011, largely because of fipronil and dichlorvos. The potential for adverse effects on aquatic life is likely greater than these results indicate because potentially important pesticide compounds were not included in the assessment. Human-health benchmarks were much less frequently exceeded, and during 2002−2011, only one agricultural stream and no urban or mixed-land-use streams exceeded human-health benchmarks for any of the measured pesticides. Widespread trends in pesticide concentrations, some downward and some upward, occurred in response to shifts in use patterns primarily driven by regulatory changes and introductions of new pesticides.

Die EU-Kommission meldet "alarmierende Verlustzahlen" für Tier- und Pflanzenarten in Europa. Besonders schlecht steht es demnach um die Süßwasserfische sowie Schnecken, Muscheln und andere Weichtiere. Die Zahlen zeigten, "dass die europäischen Süßwasserökosysteme in der Tat ernsthaft bedroht sind und dringend Erhaltungsmaßnahmen erforderlich sind", warnte Annabelle Cuttelod von der Weltnaturschutzunion (IUCN), die jährlich die Rote Liste der gefährdeten Arten veröffentlicht. Für die europäische Ausgabe wurde den Angaben zufolge mit rund 6000 Arten ein "erheblicher Teil" der in Europa heimischen Fauna und Flora untersucht.In der Roten Liste sind 37 Prozent der Süßwasserfische als "gefährdet", "stark gefährdet" oder "vom Aussterben bedroht" eingestuft. Bei den in Flüssen und Seen lebenden Weichtieren sind es sogar 44 Prozent. Besonders stark betroffen ist beispielsweise der Stör: Sieben der acht europäischen Arten sind demnach "stark gefährdet". Des Weiteren gelten 23 Prozent der Amphibien und 19 Prozent der Reptilien als gefährdet. Jede fünfte an Land lebende Weichtierart ist den Daten zufolge bedroht, ebenso 15 Prozent der Säugetierarten und 13 Prozent der Vögel. Rund 26 Prozent der Gefäßpflanzen - das sind alle Pflanzen außer den Moosen - werden auf der aktuellen Roten Liste ebenfalls als bedroht eingestuft.

According to the Living Planet Report report, populations of fish, birds, mammals, amphibians and reptiles have declined by 52 per cent since 1970. Freshwater species have suffered a 76 per cent decline, an average loss almost double that of land and marine species. “Biodiversity is a crucial part of the systems that sustain life on Earth – and the barometer of what we are doing to this planet, our only home. We urgently need bold global action in all sectors of society to build a more sustainable future,” said WWF International Director General Marco Lambertini. Biodiversity declines in Africa highlight the intense pressure felt by tropical species. For the thousands of species tracked by the report, the tropics showed a 56 per cent loss across populations compared to 36 per cent in temperate zones. “The unique nature and natural resources of Africa are under more pressure than ever before. Life-sustaining ecosystems are rapidly degrading, thus compromising the future security, health and well-being of millions of African people, with the poor heavily and disproportionately bearing the brunt of these losses,” said Fred Kumah, Director of Africa at WWF International.

The rufa red knot (Calidris canutus) is truly a master of long-distance aviation. On wingspans of 20 inches, some knots fly more than 9,300 miles from south to north every spring and repeat the trip in reverse every autumn, making this bird one of the longest-distance migrants in the animal kingdom. Surveys of wintering knots along the coasts of southern Chile and Argentina and during spring migration in Delaware Bay on the U.S. coast indicate that a serious population decline occurred in the 2000s. The knot’s unique and impressive life history depends on suitable habitat, food and weather conditions at far-flung sites across the Western Hemisphere, from the extreme south of Tierra del Fuego to the far north of the central Canadian Arctic. Knots need to encounter these favorable habitat, food and weather conditions within narrow seasonal windows as the birds hopscotch along migration stopovers between wintering and breeding areas. For example, the knot population decline that occurred in the 2000s was caused primarily by reduced food availability from increased harvests of horseshoe crabs, exacerbated by small changes in the timing that knots arrived at the Delaware Bay. Horseshoe crab harvests are now managed with explicit goals to stabilize and recover knot populations.

The removal of top predators has been called “humankind’s most pervasive influence on nature,” and it is as detrimental in the sea as it is on land. Consumers prefer predatory fish like grouper, tuna, swordfish and sharks to species lower on the food chain such as anchovies and sardines, providing strong incentives for fishermen to catch the bigger fish. Going after the more valuable predators first, fishing them until there aren’t enough left to support a fishery and then moving on to species lower in the food chain, a pattern sometimes observed in global fisheries, has been called “fishing down the food web.” New research by the team that coined the term attempts to determine how severely predatory fish populations have declined worldwide since the start of industrial fishing. Scientists analyzed more than 200 published food-web (interacting food chains) models from all over the world, which included more than 3,000 ocean species. Their results show that in the 20th century humans reduced the biomass of predatory fishes by more than two thirds and that most of this alarming decline has occurred since the 1970s.

The rivers and streams of the Paci­fic Northwest used to be so full of wild salmon that fishermen liked to say they could cross the waterways on the fish's backs. If salmon were the only means of crossing the rivers, those fishermen would be out of luck today. In California, Washington, Oregon and Idaho, salmon are extinct in nearly 40 percent of the rivers they were known to inhabit -- at least 106 major stocks gone forever [source: Northwest Power & Conservation Council]. Around the world, the story is much the same: Global Atlantic salmon catches fell 80 percent from 1970 to 2000. In the United Kingdom, one-third of the salmon population is endangered according to the WWF, and in California and Oregon, the Pacific Fishery Management Council recently announced the strictest salmon fishing quotas in the region's history due to the animal's rapid decline [source: Young, Environment News Service]. The downward spiral of the salmon population is troubling for several reasons. This fish is far more than just a tasty source of omega-3s. Salmon are what's known as a keystone species -- like the engine in your car, their physical presence compared to the whole is rather small, but their importance to its functioning is vital. Not only are the fish a main source of sustenance for a variety of predators (more than 137 species), but their decomposing carcasses are a significant source of nutrients and fertilizer for trees [source: Hunt]. When the salmon go, the surrounding ecosystem likely won't be far behind.

Neonicotinoids, broad-spectrum systemic insecticides, are the fastest growing class of insecticides worldwide and are now registered for use on hundreds of field crops in over 120 different countries. The environmental profile of this class of pesticides indicate that they are persistent, have high leaching and runoff potential, and are highly toxic to a wide range of invertebrates. Therefore, neonicotinoids represent a significant risk to surface waters and the diverse aquatic and terrestrial fauna that these ecosystems support. This review synthesizes the current state of knowledge on the reported concentrations of neonicotinoids in surface waters from 29 studies in 9 countries world-wide in tandem with published data on their acute and chronic toxicity to 49 species of aquatic insects and crustaceans spanning 12 invertebrate orders. Strong evidence exists that water-borne neonicotinoid exposures are frequent, long-term and at levels (geometric means = 0.13 μg/L (averages) and 0.63 μg/L (maxima)) which commonly exceed several existing water quality guidelines.

Birds that dive for fish while wintering in the Salish Sea, located between British Columbia and Washington, are more likely to be in decline than nondiving birds with less specialized diets, according to a study led by the School of Veterinary Medicine at the University of California, Davis. Diving birds were 11 times more likely to be in decline than nondiving birds, according to the study, published in the journal Conservation Biology. Also, populations of diving birds that rely on forage fish, such as Pacific herring, are 16 times more likely to decline than those with more varied diets. The study lends credence to what scientists have long suspected: “If you want to recover birds, you need to recover the food that they’re eating,” said co-author Joe Gaydos, a UC Davis wildlife veterinarian and director of the SeaDoc Society, a program of the UC Davis Karen C. Drayer Wildlife Health Center. “This could help puffins (Fratercula arctica), western grebes (Aechmophorus occidentalis), common murres (Uria aalge) and other diving species recover.”