Gefährdung mittelamerikanischer Froschlurche

[Ralf Rombach]

Hallo,

ich stelle die Frage mal hier rein.

Es gab vor einiger Zeit (wenige Jahre ?) mal eine oder mehrere Veröffentlichungen zum Rückgang von Froschlurchen in mittelamerikanischen, primären Regenwälder.

Ich habe leider die Quellen nicht mehr, kann mir da vielleicht jemand weiterhelfen ?

Danke im voraus und besten Gruß

Ralf

[Maha]

Re: Gefährdung mittelamerikanischer Froschlurche

Soweit ich weiss, gibt es dazu inzwischen jede Menge Literatur. Was für welche suchst Du denn (das die Artenzahlen zurück gehen? mögliche Ursachen? mögliche Gegenmassnahmen? usw.)?

Grüße Johannes


PS: das folgende Buch behandelt das Problem weltweit, ist aber trotzdem sehr gut:
Author Name: Semlitsch, Raymond D. (editor)
Title: Amphibian Conservation
Publisher: Washington, DC, U.S.A. Smithsonian Institution Press 2003
ISBN Number: 1588341194
324 pages, illustrated

[Ralf Rombach]

Re: Gefährdung mittelamerikanischer Froschlurche

Hallo Johannes,

danke für die Info und die Quelle, werde mal versuchen, das Buch zu ordern.

Mit ging es um die Artenzahlen in den primären Regenwälder, später nach dem ich das Post abgesetzt hatte, fiel mir noch ein, daß es ein Fernsehbericht irgendwann in den letzten beiden Jahren war, wo auf die Rückgänge von Amphibien in intakten, primären Regenwäldern hingewiesen wurde. Ursachen nach diesem Bericht waren zu dem Zeitpunkt unbekannt, man konnte nur spekulieren. War irgendwann in den letzten beiden Jahren.

Danke und besten Gruss

Ralf

[Maha]

Re: Gefährdung mittelamerikanischer Froschlurche

Hallo Ralf,

so auf die schnelle habe ich zu Zentralamerika nur das folgende gefunden. Konkrete Artenzahlen zu finden wird sehr schwer, da das Aussterben konkret recht schwer nachzuweisen ist. Meist geht es darum Gründe und Ursachen zu finden. Sorry, aber ich habe momentan nicht mehr Zeit zum Suchen, aber vielleicht ist ja etwas passendes dabei:

TI: Potential causes for amphibian declines in Puerto Rico.
AU: Burrowes,-Patricia-A {a}; Joglar,-Rafael-L; Green,-David-E
AD: {a} Univ Puerto Rico, Dept Biol, P.O. Box 23360, San Juan, PR 00931-3360, USA; E-mail: pburrowe@upracd.upr.clu.edu
SO: Herpetologica. 2004 June; 60(2): 141-154
IS: 0018-0831
PY: 2004
DT: Article; Print
LA: English
LS: English
AB: We monitored 11 populations of eight species of Eleutherodactylus in Puerto Rico from 1989 through 2001. We determined relative abundance of active frogs along transects established in the Caribbean National Forest (El Yunque), Carite Forest, San Lorenzo, and in the vicinity of San Juan. Three species (Eleutherodactylus karlschmidti, E. jasperi, and E. eneidae) are presumed to be extinct and eight populations of six different species of endemic Eleutherodactylus are significantly declining at elevations above 400 m. Of the many suspected causes of amphibian declines around the world, we focused on climate change and disease. Temperature and precipitation data from 1970-2000 were analyzed to determine the general pattern of oscillations and deviations that could be correlated with amphibian declines. We examined a total of 106 tissues taken from museum specimens collected from 1961-1978 and from live frogs in 2000. We found chytrid fungi in two species collected at El Yunque as early as 1976, this is the first report of chytrid fungus in the Caribbean. Analysis of weather data indicates a significant warming trend and an association between years with extended periods of drought and the decline of amphibians in Puerto Rico. The 1970's and 1990's, which represent the periods of amphibian extirpations and declines, were significantly drier than average. We suggest a possible synergistic interaction between drought and the pathological effect of the chytrid fungus on amphibian populations.

TI: The herpetofauna of the cloud forests of Honduras.
AU: Wilson,-Larry-David {a}; McCranie,-James-R
AD: {a} Department of Biology, Miami-Dade Community College, Kendall Campus, Miami, FL, 33176-3393, USA; E-mail: lwilson@mdcc.edu
SO: Amphibian-and-Reptile-Conservation. 2004; 3(1): 34-48
IS: 1083-446X
PY: 2004
DT: Article; Print
LA: English
LS: English; Spanish
AB: The cloud forest amphibians and reptiles constitute the most important herpetofaunal segment in Honduras, due to the prevalence of endemic and Nuclear Middle American-restricted species. This segment, however, is subject to severe environmental threats due to the actions of humans. Of the 334 species of amphibians and reptiles currently known from Honduras, 122 are known to be distributed in cloud forest habitats. Cloud forest habitats are found throughout the mountainous interior of Honduras. They are subject to a Highland Wet climate, which features annual precipitation of >1500 mm and a mean annual temperature of <18[degree]C. Cloud forest vegetation falls into two Holdridge formations, the Lower Montane Wet Forest and Lower Montane Moist Forest. The Lower Montane Wet Forest formation generally occurs at elevations in excess of 1500 m, although it may occur as low as 1300+ m at some localities. The Lower Montane Moist Forest formation generally occurs at 1700+ m elevation. Of the 122 cloud forest species, 18 are salamanders, 38 are anurans, 27 are lizards, and 39 are snakes. Ninety-eight of these 122 species are distributed in the Lower Montane Wet Forest formation and 45 in the Lower Montane Moist Forest formation. Twenty species are distributed in both formations. The cloud forest species are distributed among restricted, widespread, and peripheral distributional categories. The restricted species range as a group in elevation from 1340 to 2700 m, the species that are widespread in at least one of the two cloud forest formations range as a group from sea level to 2744 m, and the peripheral species range as a group from sea level to 1980 m. The 122 cloud forest species exemplify ten broad distributional patterns ranging from species whose northern and southern range termini are in the United States (or Canada) and South America, respectively, to those species that are endemic to Honduras. The largest segment of the herpetofauna falls into the endemic category, with the next largest segment being restricted in distribution to Nuclear Middle America, but not endemic to Honduras. Cloud forest species are distributed among eight ecophysiographic areas, with the largest number being found in the Northwestern Highlands, followed by the North-Central Highlands and the Southwestern Highlands. The greatest significance of the Honduran herpetofauna lies in its 125 species that are either Honduran endemics or otherwise Nuclear Middle American-restricted species, of which 83 are distributed in the country's cloud forests. This segment of the herpetofauna is seriously endangered as a consequence of exponentially increasing habitat destruction resulting from deforestation, even given the existence of several biotic reserves established in cloud forest. Other, less clearly evident environmental factors also appear to be implicated. As a consequence, slightly over half of these 83 species (50.6%) have populations that are in decline or that have disappeared from Honduran cloud forests. These species possess biological, conservational, and economic significance, all of which appear in danger of being lost.

TI: The conservation status of the herpetofauna of Honduras.
AU: Wilson,-Larry-David {a}; McCranie,-James-R
AD: {a} Department of Biology, Miami-Dade Community College, Kendall Campus, Miami, FL, 33176-3393, USA; E-mail: lwilson@mdcc.edu
SO: Amphibian-and-Reptile-Conservation. 2004; 3(1): 6-33
IS: 1083-446X
PY: 2004
DT: Article; Print
LA: English
LS: English; Spanish
AB: The conservation status of the members of the Honduran herpetofauna is discussed. Based on current and projected future human population growth, it is posited that the entire herpetofauna is endangered. The known herpetofauna of Honduras currently consists of 334 species, including 117 amphibians and 217 reptiles (including six marine reptiles, which are not discussed in this paper). The greatest number of species occur at low and moderate elevations in lowland and/or mesic forest formations, in the Northern and Southern Cordilleras of the Serrania, and the ecophysiographic areas of the Caribbean coastal plain and foothills. Slightly more than one-third of the herpetofauna consists of endemic species or those otherwise restricted to Nuclear Middle America. Honduras is an area severely affected by amphibian population decline, with close to one-half of the amphibian fauna threatened, endangered, or extinct. The principal threats to the survival of members of the herpetofauna are uncontrolled human population growth and its corollaries, habitat alteration and destruction, pollution, pest and predator control, overhunting, and overexploitation. No Honduran amphibians or reptiles are entirely free of human impact. A gauge is used to estimate environmental vulnerability of amphibian species, using measures of extent of geographic range, extent of ecological distribution, and degree of specialization of reproductive mode. A similar gauge is developed for reptiles, using the first two measures for amphibian vulnerability, and a third scale for the degree of human persecution. Based on these gauges, amphibians and reptiles show an actual range of Environmental Vulnerability Scores (EVS) almost as broad as the theoretical range. Based on the actual EVS, both amphibian and reptilian species are divided into three categories of low, medium, and high vulnerability. There are 24 low vulnerability amphibians and 47 reptiles, 43 medium vulnerability amphibians and 111 reptiles, and 50 high vulnerability amphibians and 53 reptiles. Theoretical EVS values are assessed against available information on current population status of endemic and Nuclear Middle American taxa. Almost half (48.8%) of the endemic species of Honduran amphibians are already extinct or have populations that are in decline. Populations of 40.0% of the Nuclear Middle American amphibian species are extirpated or in decline. A little less than a third (27.0%) of the endemic reptiles are thought to have declining populations. Almost six of every ten (54.5%) of the Nuclear Middle American reptilian species are thought to have declining populations. EVS values provide a useful indicator of potential for endangerment, illustrating that the species whose populations are currently in decline or are extinct or extirpated have relatively high EVS. All high EVS species need to be monitored closely for changes in population status. A set of recommendations are offered, assuming that biotic reserves in Honduras can be safeguarded, that it is hoped will lead to a system of robust, healthy, and economically self-sustaining protected areas for the country's herpetofauna. These recommendations will have to be enacted swiftly, however, due to unremitting pressure from human population growth and the resulting deforestation.

TI: Neotropical tadpoles influence stream benthos: Evidence for the ecological consequences of decline in amphibian populations.
AU: Ranvestel,-Anthony-W; Lips,-Karen-R {a}; Pringle,-Catherine-M; Whiles,-Matt-R; Bixby,-Rebecca-J
AD: {a} Department of Zoology, Southern Illinois University, Carbondale, IL 62901, USA; E-mail: klips@zoology.siu.edu
SO: Freshwater-Biology. 2004 March; 49(3): 274-285
IS: 0046-5070
PY: 2004
DT: Article; Print
LA: English
LS: English
AB: 1. Few studies have assessed the role of tadpoles in tropical streams, although they are often abundant and conspicuous components of these systems. Moreover, amphibian populations are declining around the globe, particularly stream-dwelling species in tropical uplands, and the ecological consequences of these losses are not understood. 2. We chose a stream in the central Panamanian highlands, which has an intact fauna of stream-breeding anurans, to examine the ecological consequences of amphibian losses. This site differs dramatically from sites in nearby western Panama and Costa Rica where anuran diversity and abundance have declined greatly in the last two decades. 3. We used an underwater electric field to create tadpole exclosures in runs, so that we could evaluate their influence on sediment dynamics and the abundance and community structure of algae and aquatic insects. Tadpoles reduced total sediments and both organic and inorganic fractions on substrata. Tadpoles also reduced algal abundance on substrata by approximately 50% and decreased algal biovolume. Gut content analyses showed that tadpoles consumed algae and sediments and we could see that algae and sediments were also displaced through bioturbation. 4. Atelopus zeteki, Rana warszewitschii, and Hyla spp. were the dominant larval anurans responsible for the effects observed. Visual surveys indicated that the densities of these taxa ranged from 23 (R. warszewitschii and Hyla spp. combined) to 43 m-2 (A. zeteki) in runs. 5. The abundance of baetid mayflies was lower in tadpole exclosures compared with controls, and this was attributed to tadpoles facilitating mayfly feeding by removing sediments and exposing underlying periphyton. 6. Tadpoles affect the abundance and diversity of basal resources and other primary consumers, and thus influence food web dynamics and energy flow in these tropical streams. Catastrophic decline in stream-breeding anuran populations will influence the structure and function of neotropical stream ecosystems.

TI: Chytridiomycosis in wild frogs from southern Costa Rica.
AU: Lips,-Karen-R {a}; Green,-D-Earl; Papendick,-Rebecca
AD: {a} Department of Zoology, Southern Illinois University, Carbondale, IL, 62901-6501, USA; E-mail: klips@zoology.siu.edu
SO: Journal-of-Herpetology. 2003 March; 37(1): 215-218
IS: 0022-1511
PY: 2003
DT: Article; Print
LA: English
LS: English
AB: In 1993, the amphibian fauna of Las Tablas, Costa Rica, began to decline, and by 1998 approximately 50% of the species formerly present could no longer be found. Three years later, at the Reserva Forestal Fortuna, in western Panama, a site approximately 75 km east southeast of Las Tablas, KRL encountered a mass die-off of amphibians and a subsequent decline in abundance and species richness. The epidemiological features of the anuran population declines and die-offs at both sites were similar, suggesting a similar cause. Herein we document the presence of the fungus, Batrachochytrium dendrobatidis, in dead and dying wild frogs collected at Las Tablas just prior to population declines of several anuran species.

TI: Climate variability in regions of amphibian declines.
AU: Alexander,-Michael-A {a}; Eischeid,-Jon-K
AD: {a} Climate Diagnostics Center, National Oceanic and Atmospheric Administration - Cooperative Institute for Research in Environmental Sciences, Mail Code R/CDCI, 325 Broadway, Boulder, CO 80305-3328, USA
SO: Conservation-Biology. 2001 August; 15(4): 930-942
IS: 0888-8892
PY: 2001
DT: Article; Print
LA: English
LS: English; Spanish

TI: Amphibian declines in Central and South America.
AU: Prohl,-Heike {a}
AD: {a} Institut fur Zoologie, Tierarztliche Hochschule Hannover, Bunteweg 17, 30559 Hannover, Germany
SO: Mesoamericana. 1999 Marzo; 4(1): 20-26
PY: 1999
DT: Article; Print
LA: English; Spanish

TI: Decline of a tropical montane amphibian fauna.
AU: Lips,-Karen-R {a}
AD: {a} Department of Biology, St. Lawrence University, Canton, NY 13617, USA
SO: Conservation-Biology. 1998 February; 12(1): 106-117
IS: 0888-8892
PY: 1998
DT: Article; Print
LA: English
LS: English; Spanish

TI: Tests of null models for amphibian declines on a tropical mountain.
AU: Pounds,-J-Alan; Fogden,-Michael-PL {a}; Savage,-Jay-M; Gorman,-George-C
AD: {a} Department of Biology, University of Miami, P.O. Box 249118, Coral Gables, FL 33124-0421, USA
SO: Conservation-Biology. 1997 December; 11(6): 1307-1322
IS: 0888-8892
PY: 1997
DT: Article; Print
LA: English
LS: English; Spanish

TI: Amphibian declines and climate disturbance: the case of the golden toad and the harlequin frog.
AU: Pounds,-J-Alan; Crump,-Martha-L
SO: Conservation-Biology. 1994 March; 8(1): 72-85
IS: 0888-8892
PY: 1994
DT: Article; Print
LA: English
LS: English; Spanish

Für den amazonischen Wald gibt es folgendes:

Funk WC & Mills LS (2003) Potential causes of population declines in forest fragments in an Amazonian frog. Biological Conservation 111: 205-214.

Allgemeinere Paper zu dem Thema waren auf die Schnelle folgende:

Biek R et al. (2002) What is missing in Amphibian Decline Research: Insights from Ecological Sensitivity Analysis. Conservation Biology 16 (3): 728-734.


Green D (2003) The ecology of extinction: population fluctuation and decline in amphibians. Biological Conservation 111: 331-343.

Collins JP & Storfer A (2003) Global amphibian declines: sorting the hypothesis. Diversity and Distributions 9: 89-98.

Storfer A (2003) Amphibian declines: future directions. Diversity and Distribution 9: 151-163.

Carey C & Alexander MA (2003) Climate change and amphibian declines: is there a link? Diversity and Distribution 9: 111-121.

Hecnar SJ & M'Closkey RT (1996) Regional dynamics and the status of amphibians. Ecology 77 (7): 2091-2097.

Skelly DK et al. (2003) Estimating Decline and Distributional Change in Amphibians. Conservation Biology 17 (3): 744-751.

Ich hoffe das hilft Dir weiter...

Grüße Johannes

[Ralf Rombach]

Re: Gefährdung mittelamerikanischer Froschlurche

Johannes,

super, danke.

Gruss Ralf