Freshwater biodiversity is the over-riding conservation priority during the International Decade for Action - 'Water for Life' - 2005 to 2015. Fresh water makes up only 0.01% of the World's water and approximately 0.8% of the Earth's surface, yet this tiny fraction of global water supports at least 100000 species out of approximately 1.8 million - almost 6% of all described species. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. Their conservation and management are critical to the interests of all humans, nations and governments. Yet this precious heritage is in crisis. Fresh waters are experiencing declines in biodiversity far greater than those in the most affected terrestrial ecosystems, and if trends in human demands for water remain unaltered and species losses continue at current rates, the opportunity to conserve much of the remaining biodiversity in fresh water will vanish before the 'Water for Life' decade ends in 2015. Why is this so, and what is being done about it? This article explores the special features of freshwater habitats and the biodiversity they support that makes them especially vulnerable to human activities. We document threats to global freshwater biodiversity under five headings: overexploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species. Their combined and interacting influences have resulted in population declines and range reduction of freshwater biodiversity worldwide. Conservation of biodiversity is complicated by the landscape position of rivers and wetlands as 'receivers' of land-use effluents, and the problems posed by endemism and thus non-substitutability. In addition, in many parts of the world, fresh water is subject to severe competition among multiple human stakeholders. Protection of freshwater biodiversity is perhaps the ultimate conservation challenge because it is influenced by the upstream drainage network, the surrounding land, the riparian zone, and - in the case of migrating aquatic fauna - downstream reaches. Such prerequisites are hardly ever met. Immediate action is needed where opportunities exist to set aside intact lake and river ecosystems within large protected areas. For most of the global land surface, trade-offs between conservation of freshwater biodiversity and human use of ecosystem goods and services are necessary. We advocate continuing attempts to check species loss but, in many situations, urge adoption of a compromise position of management for biodiversity conservation, ecosystem functioning and resilience, and human livelihoods in order to provide a viable long-term basis for freshwater conservation. Recognition of this need will require adoption of a new paradigm for biodiversity protection and freshwater ecosystem management - one that has been appropriately termed 'reconciliation ecology'.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/96AA265E3D88C95FB802E7A73CCB4332/S1464793105006950a.pdf/div-class-title-freshwater-biodiversity-importance-threats-status-and-conservation-challenges-div.pdf

Freshwater biodiversity: importance, threats, status and conservation challenges

Landscape modification and habitat fragmentation are key drivers of global species loss. Their effects may be understood by focusing on: (1) individual species and the processes threatening them, and (2) human-perceived landscape patterns and their correlation with species and assemblages. Individual species may decline as a result of interacting exogenous and endogenous threats, including habitat loss, habitat degradation, habitat isolation, changes in the biology, behaviour, and interactions of species, as well as additional, stochastic threats. Human-perceived landscape patterns that are frequently correlated with species assemblages include the amount and structure of native vegetation, the prevalence of anthropogenic edges, the degree of landscape connectivity, and the structure and heterogeneity of modified areas. Extinction cascades are particularly likely to occur in landscapes with low native vegetation cover, low landscape connectivity, degraded native vegetation and intensive land use in modified areas, especially if keystone species or entire functional groups of species are lost. This review (1) demonstrates that species-oriented and pattern-oriented approaches to understanding the ecology of modified landscapes are highly complementary, (2) clarifies the links between a wide range of interconnected themes, and (3) provides clear and consistent terminology. Tangible research and management priorities are outlined that are likely to benefit the conservation of native species in modified landscapes around the world.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1466-8238.2007.00287.x

Landscape modification and habitat fragmentation: a synthesis

Nearly half the world's vascular plant species and one-third of terrestrial vertebrates are endemic to 25 "hotspots" of biodiversity, each of which has at least 1500 endemic plant species. None of these hotspots have more than one-third of their pristine habitat remaining. Historically, they covered 12% of the land's sur- face, but today their intact habitat covers only 1.4% of the land. As a result of this habitat loss, we expect many of the hotspot endemics to have either become extinct or—because much of the habitat loss is recent— to be threatened with extinction. We used World Conservation Union (IUCN) Red Lists to test this expectation. Overall, between one-half and two-thirds of all threatened plants and 57% of all threatened terrestrial verte- brates are hotspot endemics. For birds and mammals, in general, predictions of extinction in the hotspots based on habitat loss match numbers of species independently judged extinct or threatened. In two classes of hotspots the match is not as close. On oceanic islands, habitat loss underestimates extinction because intro- duced species have driven extinctions beyond those caused by habitat loss on these islands. In large hotspots, conversely, habitat loss overestimates extinction, suggesting scale dependence (this effect is also apparent for plants). For reptiles, amphibians, and plants, many fewer hotspot endemics are considered threatened or ex- tinct than we would expect based on habitat loss. This mismatch is small in temperate hotspots, however, sug- gesting that many threatened endemic species in the poorly known tropical hotspots have yet to be included on the IUCN Red Lists. We then asked in which hotspots the consequences of further habitat loss (either abso- lute or given current rates of deforestation) would be most serious. Our results suggest that the Eastern Arc and Coastal Forests of Tanzania-Kenya, Philippines, and Polynesia-Micronesia can least afford to lose more habitat and that, if current deforestation rates continue, the Caribbean, Tropical Andes, Philippines, Me- soamerica, Sundaland, Indo-Burma, Madagascar, and Choco-Darien-Western Ecuador will lose the most spe- cies in the near future. Without urgent conservation intervention, we face mass extinctions in the hotspots.

Habitat Loss and Extinction in the Hotspots of Biodiversity

Current predictions of extinction risks from climate change vary widely depending on the specific assumptions and geographic and taxonomic focus of each study. I synthesized published studies in order to estimate a global mean extinction rate and determine which factors contribute the greatest uncertainty to climate change–induced extinction risks. Results suggest that extinction risks will accelerate with future global temperatures, threatening up to one in six species under current policies. Extinction risks were highest in South America, Australia, and New Zealand, and risks did not vary by taxonomic group. Realistic assumptions about extinction debt and dispersal capacity substantially increased extinction risks. We urgently need to adopt strategies that limit further climate change if we are to avoid an acceleration of global extinctions.

Accelerating extinction risk from climate change

Aim We explore the relationship between current European distributions of amphibian and reptile species and observed climate, and project species potential distributions into the future. Potential impacts of climate warming are assessed by quantifying the magnitude and direction of modelled distributional shifts for every species. In particular we ask, first, what proportion of amphibian and reptile species are projected to lose and gain suitable climate space in the future? Secondly, do species projections vary according to taxonomic, spatial or environmental properties? And thirdly, what climate factors might be driving projections of loss or gain in suitable environments for species?

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2699.2006.01482.x

Climate warming and the decline of amphibians and reptiles in Europe

A s a group [reptiles] are nei t h er ‘good ’n or ‘b ad ,’ but ia re intere s ting and unu su a l , a l t h o u gh of m i n or i m port a n ce . If t h ey should all disappe a r, it wo u l d not make mu ch differen ce one way or the other ”( Zim and Smith 1953, p. 9 ) . Fortu n a tely, this op i n i on from the Golden Gu i de Series does not persist tod ay; most people have com e to recogn i ze the va lue of both reptiles and amph i bians as an i n tegral part of n a tu ral eco s ys tems and as heralds of envi ron m ental qu a l i ty (Gibbons and Stangel 1999). In recent ye a rs , as overa ll envi ron m ental aw a reness among the p u blic has incre a s ed , con cerns have come to inclu de intere s t in the eco l ogical state of reptile and amph i bian spec i e s t h em s elves and of t h eir habi t a t s . In c re a s ed aw a reness may s tem from bet ter edu c a ti on abo ut threats to bi od ivers i ty in gen era l , and to reptiles and amph i bians in parti c u l a r, a n d po s s i bly even from an innate attracti on to these taxa ( Kell ert and Wi l s on 1993). From the perspective of many nonscientists, the two vertebrate classes comprising reptiles and amphibians, collectively referred to as the herpetofauna, are interchangeable. For example,the Boy Scout merit badge pamphlet for herpetology was called simply Reptile Study from 1926 to 1993 (Conant 1972, Gibbons 1993), and major zoos (e.g., National Zoo in Washington, DC; Zoo Atlanta; and San Diego Zoo) use only the name “reptile” to refer to the facility that houses both amphibians and reptiles. Thus, public attitudes about the need for conservation of reptiles are probably linked to concern about amphibian declines and deformities (Alford and Richards 1999, Johnson et al. 1999, Sessions et al. 1999), which have been the subject of numerous, well-documented scientific studies. Because amphibians are distributed worldwide, but herpetologists who document amphibian declines are not, it is difficult to accurately assess what portion of amphibian populations are experiencing significant declines or have already disappeared. Furthermore, the means of determining a species’ conservation status is a rigorous and time-intensive process, and therefore counts of “officially” recognized endangered and threatened species are likely to grossly underestimate the actual number of imperiled s pecies (Ta ble 1). The worl dwi de amph i bian decl i n e probl em , as it has come to be known, has garnered significant attention not only among scientists but also in the popular media and in political circles.

/pdf/the-global-decline-of-reptiles-deja-vu-amphibians-594oge2sdh.pdf

The global decline of reptiles, deja’ vu amphibians

Screen-washing of unconsolidated fossiliferous sediments from the late Neogene Pipe Creek Sinkhole (Grant County, Indiana) yielded two coprolites. Maximum preserved diameter of both is about 26 mm, and both are apatitic in composition. Although one coprolite is largely amorphous internally, the other preserves remnants of hair and at least two teeth of a small carnivoran. The crowns of both teeth are highly corroded, and the enamel of one of the teeth has been completely removed. Although large turtles cannot be excluded as the scat-makers, the most likely candidate is a wolf-sized carnivoran, possibly a canid.

https://bioone.org/journals/journal-of-vertebrate-paleontology/volume-30/issue-3/02724631003762906/Coprolites-from-the-Pipe-Creek-Sinkhole-Late-Neogene-Grant-County/10.1080/02724631003762906.pdf

Coprolites from the Pipe Creek Sinkhole (Late Neogene, Grant County, Indiana, U.S.A.)

We examined the ecology of a Black Swamp Snake (Seminatrix pygaea) population inhabiting an isolated wetland in the upper Coastal Plain of South Carolina. The observed population structure was skewed towards mature individuals, with neonates and juveniles underrepresented, perhaps due to trap- ping bias. The sex ratio was biased during May and June, with females outnum- bering males, but no sex ratio bias was evident at other times of the year. Seminatrix pygaea showed sexual dimorphism in body size, with females being longer and heavier than males and males having relatively longer tails than females, but there was no difference in monthly growth rates. Approximately 76.3% of the mature females captured in May and June 1998 were pregnant. Therefore, most mature females in this population probably exhibit annual reproduction, while some undergo biennial reproduction. The majority of fe- males gave birth in July or August, with a few births occurring in September and October, and perhaps even as early as May or June. Our mark-recapture esti- mates suggest a population density greater than 60 adult snakes per hectare, which indicates this small aquatic snake, endemic to the Southeast, may play a large role as both predator and prey within isolated wetland ecosystems.

Sean M. Poppy

Papers

The global decline of reptiles, deja’ vu amphibians

Coprolites from the Pipe Creek Sinkhole (Late Neogene, Grant County, Indiana, U.S.A.)

Population Structure, Body Size, and Seasonal Activity of Black Swamp Snakes (Seminatrix pygaea)

Seminatrix pygaea . Diet.