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Amphibian Diversity on Floating Meadows in Flooded Forests of the Peruvian Amazon

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Amphibian Diversity on Floating Meadows in Flooded Forests of the Peruvian Amazon

Abstract and Figures

Floating meadows are often associated with Amazonian white-water flooded forests (varzea), where they grow between the tree line and open-water. Seasonal flooding in varzea results in an unstable forest floor for terrestrial species. However, floating meadows may offer a refuge for some species that would otherwise be displaced by rising water. Floating meadows consist of herbaceous water plants that begin growing at the end of the low water period, taking root in the waterlogged soils of river, channel and lake banks. As the water rises, some plant species grow rapidly upwards, others become free-floating and grow horizontally, expanding the surface area they occupy (Junk 1970, 1997). As water levels begin to recede, currents and rainfall can dislodge sections of floating meadows to create rafts that are then transported via the river current. The importance and diversity of floating meadows has been highlighted for several taxa (Goulding et al. 1996; Junk 1997; Schiesari et al. 2003; Dias et al. 2011; Ferreira et al. 2011), yet studies focusing on amphibian use of floating meadows are relatively scarce. Junk (1973) found that amphibians were rarely encountered on floating meadows. However, methodology was not provided by Junk (1973), and if nocturnal surveys were not undertaken, amphibians were unlikely to have been adequately sampled. Carrying out specific amphibian surveys, Hödl (1977) found 15 anuran species on floating meadows and concluded that this habitat was a potential breeding site. Hoogmoed (1993) published a list of the herpetofauna known to occur on or near to floating meadows in Suriname, Bolivia, and Brazil, adding to Hödl's (1977) list. This research brought the total number of amphibian species recorded on floating meadows to 26 (Hoogmoed 1993). On the Solimoes River, Schiesari et al. (2003) observed 42 individuals comprising eight anuran and one caecilian species, all on floating meadow rafts. They highlighted the importance of rafts of floating meadow vegetation as dispersal vectors for fish and potentially also for amphibians (Schiesari et al. 2003). In a preliminary study of only 18 days, Upton et al. (2011) found 16 anuran species on floating meadows. The amphibians recorded on floating meadow habitats to date are listed in Table 1. This paper aims to: 1) Update the current list of amphibians found on floating meadows in Peruvian varzea flooded forest, and 2) update the information on reproductive habitat use provided by Hödl (1977), which showed evidence of reproductive behavior on the floating meadow habitat
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Herpetological Review 45(2), 2014
ARTICLES 209
Herpetological Review, 2014, 45(2), 209–212.
© 2014 by Society for the Study of Amphibians and Reptiles
Amphibian Diversity on Floating Meadows in Flooded
Forests of the Peruvian Amazon
Floating meadows are often associated with Amazonian
white-water flooded forests (varzea), where they grow between
the tree line and open-water. Seasonal flooding in varzea results
in an unstable forest floor for terrestrial species. However,
floating meadows may offer a refuge for some species that would
otherwise be displaced by rising water. Floating meadows consist
of herbaceous water plants that begin growing at the end of the
low water period, taking root in the waterlogged soils of river,
channel and lake banks. As the water rises, some plant species
grow rapidly upwards, others become free-floating and grow
horizontally, expanding the surface area they occupy (Junk 1970,
1997). As water levels begin to recede, currents and rainfall can
dislodge sections of floating meadows to create rafts that are then
transported via the river current.
The importance and diversity of floating meadows has
been highlighted for several taxa (Goulding et al. 1996; Junk
1997; Schiesari et al. 2003; Dias et al. 2011; Ferreira et al. 2011),
yet studies focusing on amphibian use of floating meadows are
relatively scarce. Junk (1973) found that amphibians were rarely
encountered on floating meadows. However, methodology was
not provided by Junk (1973), and if nocturnal surveys were not
undertaken, amphibians were unlikely to have been adequately
sampled. Carrying out specific amphibian surveys, Hödl (1977)
found 15 anuran species on floating meadows and concluded
that this habitat was a potential breeding site. Hoogmoed (1993)
published a list of the herpetofauna known to occur on or near
to floating meadows in Suriname, Bolivia, and Brazil, adding to
Hödl’s (1977) list. This research brought the total number of am-
phibian species recorded on floating meadows to 26 (Hoogmoed
1993). On the Solimoes River, Schiesari et al. (2003) observed 42
individuals comprising eight anuran and one caecilian species,
all on floating meadow rafts. They highlighted the importance of
rafts of floating meadow vegetation as dispersal vectors for fish
and potentially also for amphibians (Schiesari et al. 2003). In a
preliminary study of only 18 days, Upton et al. (2011) found 16
anuran species on floating meadows. The amphibians recorded
on floating meadow habitats to date are listed in Table 1.
This paper aims to: 1) Update the current list of amphibians
found on floating meadows in Peruvian varzea flooded forest,
and 2) update the information on reproductive habitat use
provided by Hödl (1977), which showed evidence of reproductive
behavior on the floating meadow habitat (see Hödl 1977; Fig. 3,
Table 1).
Materials and Methods
Study site.—Our study was conducted in the Samiria River
basin of the Pacaya-Samiria National Reserve, Loreto, Peru
KATY UPTON*
ELEANOR WARREN-THOMAS
ISABEL ROGERS
Durrell Institute of Conservation and Ecology,
School of Anthropology and Conservation, University of Kent,
Marlowe Building, Canterbury, Kent, CT2 7NR, UK
EMMA DOCHERTY
Fundamazonia, Malecon Tarapaca N° 332, Iquitos, Loreto, Peru
*Corresponding author; e-mail: katyfrogg@gmail.com;
k80upton@hotmail.com
taBle 1. List of amphibian species that have been recorded on, or
near, floating meadows (x = on, [x] = near). Numbers for localities:
1. Brazil, Solimões (Hödl 1977); 2. Suriname, Para River (Hoogmoed
1993); 3. Bolivia, Perserverancia (Hoogmoed 1993); 4. Brazil, Caxi-
uanã (Hoogmoed 1993); 5. Brazil, Solimões (Schiesari et al. 2003).
Species 1 2 3 4 5
ANURANS (27)
BUFONIDAE (1)
Rhinella marina x [x] x
HYLIDAE (23)
Dendropsophus haraldschultzi x
Dendropsophus leucophyllatus x x x
Dendropsophus minusculus x
Dendropsophus nanus x [x]
Dendropsophus rossalleni x
Dendropsophus triangulum x
Dendropsophus walfordi x
Hypsiboas boans x [x]
Hypsiboas geographicus [x] x
Hypsiboas lanciformis x
Hypsiboas punctatus x x x x
Hypsiboas raniceps x [x] x
Hypsiboas wavrini x
Dryaderces pearsoni x
Lysapsus boliviana x
Lysapsus caraya x
Lysapsus laevis x x
Scinax boesemani x
Scinax nebulosus x x x x
Scinax ruber x
Sphaenorhynchus carneus x x
Sphaenorhynchus dosisae x
Sphaenorhynchus lacteus x x
LEPTODACTYLIDAE (2)
Leptodactylus leptodactyloides x
Leptodactylus wagneri x [x] x
PIPIDAE (1)
Pipa pipa x
CAECILIANS (1)
TYPHLONECTIDAE (1)
Typhlonectes compressicauda x
Total species on floating meadows 15(15) 7(10) 8(10) 3(4) 9(9)
(and adjacent)
Herpetological Review 45(2), 2014
210 ARTICLES
(4.893256°S, 74.355526°W). The Pacaya-Samiria National Reserve
is one of the largest varzea forests in western Amazonia spanning
over 20000 km2 between the confluence of the Ucayali and
Marañon Rivers.
Data collection.—Preliminary data for this study were
collected in May and June 2009, with more extensive surveys
conducted from March to October 2012. Most surveys were
carried out at night from 1800–2400 h, with some daytime searches
between 1400–1700 h.
The floating meadows surveyed were located in the Samiria
River basin at PV1 Shiringal, PV2 Tacshacocha, Huishto Cocha,
and PV3 Hungurahui. These sites cover a small proportion of the
Samiria River Basin, which spans a wide area; however, they were
chosen as they have varying levels of disturbance by local fishermen
and tourism. At each site, surveys were conducted across all river
systems, in both the main Samiria River and in adjacent channels
and lakes. In total, 221 surveys were conducted, 52 in 2009 and 169
in 2012. The surveys in 2012 were split as follows: 71 in lakes, 60 in
channels, and 38 on the main Samiria River. Around the lake edges,
floating meadow surveys were conducted at 100-m intervals. Within
the channel and main river, less floating vegetation was available
to survey, so all sections were surveyed at least once. A 10-m boat
with outboard motor was slowly driven into the floating meadow
vegetation, causing it to part on either side of the boat with the aim
of reducing disturbance. On each sampling occasion, an area of 2
m on either side of the boat (50 m2 in total) was searched for fifteen
minutes. During this time, all frogs encountered were captured
and placed in individually marked pots. Time
of capture, species, behavior (e.g., calling male)
and location (including plant species and
height above water), were recorded. All surveys
were completed with one local field guide, one
biologist, and three or four student volunteers.
To locate frogs at night, one main flashlight was
used by either a guide or the biologist (CB2-L1
Clubman Deluxe, LI-ION 9.2AH half-million
candle power); all students used smaller
flashlights such as the Petzl Tikka to search.
Species identification was undertaken using
several field guides (Ouboter and Jairam 2012;
Duellman 2005; Bartlett and Bartlett 2003;
Rodriquez and Duellman 1994). Although
identification of Amazonian amphibians can
be very difficult, many of the species observed
on floating meadows are distinctive and
can be quickly identified in the hand using
identification guides. Voucher specimens were
not taken as the collection of specimens from
within this protected reserve was prohibited
under the permit and authorization being used
(Resolucion Jefatural No 005-2013-SENANP-
JEF).
Data analysis.—To analyze microhabitat
use, the data were separated into the four main
genera: Dendropsophus, Hypsiboas, Scinax, and
Sphaenorhycnhus. Kruskal-Wallis tests were
then used to determine if there were significant
differences in the median calling heights among
species in the same genus.
results
Nineteen amphibian species and 1090 individuals were
recorded on the floating meadow habitat representing four families
(Table 2). Six species have not been previously recorded on floating
meadows: Dendropsophus leali, Osteocephalus taurinus, Scarthyla
goinorum, Scinax garbei, Scinax pedromedinae, and Leptodactylus
petersii. Most of the species recorded on floating meadows were
hylids (15) compared with only two leptodactylids, one bufonid,
and one pipid. The most abundant species were Dendropsophus
triangulum and Hypsiboas punctatus with 371 and 314 individuals,
respectively. No other species was represented by more than 100
individuals. Scarthyla goinorum and Scinax pedromedinae were
both represented by only two individuals while Pipa pipa and
Hypsiboas boans were represented by just one individual each
(Table 2).
The median height in which amphibians were found and the
most commonly used (over 50% of encounters) plant species are
presented for all species observed (Fig. 1, modelled after Hödl
1977, figure 3). One species, Pipa pipa, was found swimming at the
water surface; all others were on the floating meadow or adjacent
emergent vegetation. All leptodactylid and bufonid species were
most often found on Water Lettuce (Pistia stratiotes), a species
that floats on the water surface. Paspalum repens was the most
commonly used plant species on the floating meadows and also
the most abundant in the survey area. Only in Sphaenorhychus
were there significant differences in perch height between
species (Kruskal-Wallis chi squared = 16.62, P< 0.05, df = 2), with
S. carneus occupying lower heights than S. lacteus. Calling males,
taBle 2. Species list including number of individuals captured and life stages on the float-
ing meadows of the Samiria River in Pacaya-Samiria National Reserve, during May–June
2009 and March–October 2012. F = gravid female; M = calling male; A = adult (sex un-
known); J = juvenile; *above the floating meadow either on a branch or tree trunk; ° not
previously recorded on floating meadows.
Species F M A J Total 2009 Total 2012
BUFONIDAE (1)
Rhinella marina 9 1 8
HYLIDAE (15)
Dendropsophus haraldschultzi 1 29 10 2 38
Dendropsophus leali 1 1 3
Dendropsophus rossalleni 3 23 16 10
Dendropsophus triangulum 12 106 232 21 33 338
Hypsiboas boans 1 1*
Hypsiboas lanciformis 14 8 3 25
Hypsiboas punctatus 30 38 184 62 14 300
Osteocephalus taurinus 1
Scarthyla goinorum 2
Scinax garbei 2 8 4 13
Scinax pedromedinae 2
Scinax ruber 3 1 2
Sphaenorhynchus carneus 2 28 44 6 5 75
Sphaenorhynchus dorisae 2 6 50 2 38 22
Sphaenorhynchus lacteus 1 16 50 3 22 48
LEPTODACTYLIDAE (2)
Leptodactylus leptodactyloides 23 7 16
Leptodactylus petersii 20 12° 8
PIPIDAE (1)
Pipa pipa 1 1
Total number of species 6 11 17 10 12 19
Herpetological Review 45(2), 2014
ARTICLES 211
gravid females, and juveniles were all found on floating meadows,
although only for hylids (Table 2, modelled after Hödl 1977).
Calling males were observed for 11 of the 15 hylid species while
ten species were represented by juveniles and six represented by
gravid females. Leptopdactylids were only represented by adults,
as were Rhinella marina and Pipa pipa.
discussion
Hylids were the most frequently encountered family on the
floating meadows. The two most common species, Dendropso-
phus triangulum and Hypsiboas punctatus, are either rare or ab-
sent from the adjacent terrestrial habitat (pers. obs.), highlight-
ing the importance of floating meadows for some hylid species.
Other species were only represented by one or two individuals.
One example is Pipa pipa, a fully aquatic species that is rarely en-
countered on land; this individual was caught swimming at the
surface of the water. The floating meadow root system potentially
offers refuge and cover to aquatic species such as Pipa pipa.
Few leptodactylids and bufonids were observed on the
floating meadows, as these species are usually terrestrial and
are regularly encountered on the forest floor within the leaf litter
(Allmon 1991) or on river banks (Bartlett and Bartlett 2003), and
it is therefore possible that frogs in these families are only using
floating meadows as a refuge during high water periods. In both
2009 and 2012 the water level in Pacaya-Samiria exceeded all
records from the last 100 years (Bodmer et al. 2012). During these
high water periods up to 95% of the reserve can be inundated, with
water levels reaching a depth of several meters within the forest.
This reduced availability of terrestrial habitat may have displaced
some individuals onto floating meadows.
Hödl (1977) noted frogs showing call site segregation, with
most species associated with specific plant species. Calling males
were regularly observed on the floating meadows in this study,
with most species calling from a certain plant species at similar
heights. For example the three Sphaenorhynchus species called
from significantly different heights on Paspalum repens. Anuran
morphology may influence plant choice, for example, the small S.
carneus was sometimes observed calling from Oxycoryum cubense,
a small grass species. Male S. carneus are usually between 15–18
mm and females 22–23 mm SVL, compared to S. lacteus males
which are 26–29 mm and females 36–40 mm SVL (Rodríguez
and Duellman 1994). The latter, larger species may be unable to
physically climb up on this smaller grass species. Other species
that showed preference for certain plants includes D. triangulum,
which was most commonly found on Paspalum repens, and
Fig. 1. Anuran species found on floating meadows, the most common plant species on which they were found, and the median
height at which they were found. 1) Rhinella marina 2) Dendropsophus haraldschultzi, 3) Dendropsophus leali, 4) Dendropsophus
rossalleni, 5) Dendropsophus triangulum, 6) Hypsiboas boans, 7) Hypsiboas lanciformis, 8) Hypsiboas punctatus, 9) Osteocephalus
taurinus, 10) Scarthyla goinorum, 11) Scinax garbei, 12) Scinax pedromedinae, 13) Scinax ruber, 14) Sphaenorhynchus carneus, 15)
Sphaenorhynchus dorisae, 16) Sphaenorhynchus lacteus, 17) Leptodactylus leptodactyloides, 18) Leptodactylus petersii, 19) Pipa pipa.
Herpetological Review 45(2), 2014
212 ARTICLES
H. punctatus, which was found on either Paspalum repens or
Eichhornia crassipes. This is consistent with Hödl’s (1977) findings
in which D. triangulum and H. punctatus were both observed on
plants in the genus Paspalum.
Hylids may potentially be using floating meadows for
breeding, as calling males, gravid females, egg masses, and newly
metamorphosed juveniles of twelve species were observed. These
findings are consistent with Hödl’s (1977) observations of calling
males and pairs in amplexus on floating meadows. Many hylids
are arboreal and are documented to move from higher strata to
breed in temporary or permanent pools of water in the terrestrial
habitat (Rodríguez and Duellman 1994; Bartlett and Bartlett 2003;
Dodd 2010). However the flooded forest in the Pacaya-Samiria
Reserve can be inundated for up to 6–9 months a year, resulting
in an unstable terrestrial habitat. Additionally, the draining of
floodwaters occurs rapidly, with fluctuations of up to 30 cm a day.
Thus, temporary pools are only available for short periods, if at all.
Floating meadows may be a more stable habitat, available for
the 6–9 months that the terrestrial habitat is flooded, and also offers
an opportunity to study species that are not often encountered
within the terrestrial habitat. In addition, floating meadows may
offer an important refuge for other anuran families during extreme
flooding. Marked oscillations in annual water levels are becoming
more common due to climate change (Bodmer et al. 2012). The
availability of floating meadows is dependent on the water level.
Therefore it will be important to further elucidate the role of
floating meadows in maintaining amphibian diversity in flooded
forests as seasonal flooding becomes more extreme.
Acknowledgments.—This research is supported by the University
of Kent alumni scholarship, which is fully funded by alumni of the
university. Thanks to Richard Bodmer and Richard Griffiths for sup-
port and guidance. Thanks to the Pacaya-Samiria National Reserve
Authority (SERNANP) (Resolucion Jefatural No 005-2013-SENANP-
JEF) for authorization and permission to conduct this research, and
to the following for helping to fund this project and for logistical
support: Durrell Institute of Conservation and Ecology, FundAma-
zonia, Wildlife Conservation Society, Earthwatch Institute, Opera-
tion Wallacea and Operation Earth. Finally we thank all the Earth-
watch, DICE, Operation Wallacea, and Operation Earth volunteers
as well as Sophie Rost, Hannah Conduit, Lizz Willott, Abbie Parke,
Elizabeth Wells, and Eric Woebbe.
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The Amazon catchment is the largest river basin on earth, and up to 30% of its waters flow across floodplains. In its open waters, floating plants known as floating meadows abound. They can act as vectors of dispersal for their associated fauna and, therefore, can be important for the spatial structure of communities. Here, we focus on amphibian diversity in the Amazonian floating meadows over large spatial scales. We recorded 50 amphibian species over 57 sites, covering around 7000 km along river courses. Using multi-site generalised dissimilarity modelling of zeta diversity, we tested Hanski's core-satellite hypothesis and identified the existence of two functional groups of species operating under different ecological processes in the floating meadows. 'Core' species are associated with floating meadows, while 'satellite' species are associated with adjacent environments, being only occasional or accidental occupants of the floating vegetation. At large scales, amphibian diversity in floating meadows is mostly determined by stochastic (i.e. random/neutral) processes, whereas at regional scales, climate and deterministic (i.e. niche-based) processes are central drivers. Compared with the turnover of 'core' species, the turnover of 'satellite' species increases much faster with distances and is also controlled by a wider range of climatic features. Distance is not a limiting factor for 'core' species, suggesting that they have a stronger dispersal ability even over large distances. This is probably related to the existence of passive long-distance dispersal of individuals along rivers via vegetation rafts. In this sense, Amazonian rivers can facilitate dispersal, and this effect should be stronger for species associated with riverine habitats such as floating meadows.
... These lakes are usually covered by aquatic macrophytes for which growth is favoured by a combination of high solar incidence and large sediment loads from the Andes, which generate nutrient-rich water and substrate (Junk 1997). Aquatic macrophytes within lakes generate vertical stratification above and below water, which causes higher levels of environmental heterogeneity compared to vegetation-free lakes (Thomaz et al. 2008), which ultimately provide breeding, foraging, refuge and offspring development sites for a wide variety of animals (Schiesari et al. 2003;Upton et al. 2014). Additionally, macrophytes may detach from the lake bank, carrying associated fauna when lakes are connected to rivers by seasonal rainfall, and consequently causing long-distance dispersal and gene flow, which may limit the condition of rivers as biogeographic barriers (Schiesari et al. 2003). ...
... While underwater roots and stems of macrophytes are refuge and foraging sites for fish (Sanchez-Botero & Ara ujo-Lima 2001;Schiesari et al. 2003), insects (Junk 1973) and tadpoles (Schiesari et al. 2003;B€ oning et al. 2017), above-water stems and leaves are perches for a wide variety of invertebrates (Junk 1973) and vertebrates (H€ odl 1977;Hoogmoed 1993;Petermann 1997;Upton et al. 2014) not strictly aquatic in at least some life stage. Therefore, aquatic macrophyte meadows are interface ecosystems between terrestrial and aquatic habitats. ...
... All species we sampled are widely distributed over the Amazon rainforests and have been found occupying aquatic macrophytes (Upton et al. 2014;B€ oning et al. 2017;Ramalho et al. 2017). However, despite the wide distribution at macroscales, our models detected non-random frog assemblages composed of species locally restricted to optimal fractions of environmental gradients. ...
Article
en Investigating non‐random assemblages emerging in response to environmental gradients is relevant to understand mechanisms and processes affecting biodiversity. Species may be filtered from fractions of environmental gradients that limit dispersal, survival or ontogenetic development, which ultimately leads to biotic complementarities among sites. Non‐random assemblages as a response to environmental filtering have been widely demonstrated in Amazonian forests, but are rarely assessed in non‐forest ecosystems such as macrophyte meadows covering lakes. In this study, we sampled 50 plots (50 m long, 6 m wide) along continuous macrophyte meadows in a lake system in the lower Amazon River. Our main goal is to test the effects of distance from the lake bank, macrophyte height and composition (frequency of morphotype occurrence), air temperature and physicochemical properties of water (pH, dissolved oxygen, depth and temperature) on frog α and β‐diversity estimates, and frequency of species traits occurrence (abundance‐weighted body size, toe pads, foot webbing and tadpole habit). We found 16 species, for which local assemblages quantified by α and β‐diversity estimates were not random, but predicted by macrophyte height, morphotype composition and water depth. We have explicitly shown that species are filtered from fractions of these gradients through ecomorphological relationships, since morphological traits and tadpole habits were also selected by the vertical stratification provided by the vegetation cover and water depth. Overall, we present an investigation of assemblage ecology that is relevant to conservation, because the results suggest biotic complementarities within habitats that are rarely considered as distinct biogeographic units from the surrounding várzea forests. Abstract in Portuguese is available with online material. Resumo es Investigar assembleias não aleatórias determinadas por meio de respostas das espécies a gradientes ambientais é relevante para compreendermos mecanismos e processos que afetam a biodiversidade. Espécies podem ser filtradas de porções de gradientes ambientais que limitam a dispersão, a sobrevivência ou o desenvolvimento ontogenético, o que em última instância gera complementaridade biótica entre locais. Assembleias não aleatórias em resposta a filtragem ambiental têm sido amplamente demonstradas em florestas Amazônicas, mas raramente em ecossistemas não florestais, como bancos de macrófitas aquáticas em lagos de várzea. Neste estudo, amostramos 50 parcelas (50 m de comprimento por 6 m de largura) distribuídas ao longo de bancos contínuos de macrófitas em um sistema de lagos no baixo Rio Amazonas. Nosso principal objetivo é testar os efeitos da distância da margem do lago, altura e composição de macrófitas (frequência de ocorrência de morfotipos), temperatura do ar e propriedades físico‐químicas da água (pH, oxigênio dissolvido, profundidade e temperatura) sobre estimativas de diversidade α e β de anfíbios anuros, e frequência de ocorrência de traços funcionais das espécies amostradas (tamanho do corpo ponderado pela abundância, frequência de ocorrência de discos adesivos e membranas interdigitais, e hábitos de vida dos girinos). Encontramos 16 espécies de anuros, para as quais a distribuição de assembleias locais quantificadas pelas estimativas de diversidade α e β não foram aleatórias, mas afetadas pela altura das macrófitas, composição de morfotipos e profundidade da água. Mostramos explicitamente que as espécies são filtradas de determinadas porções desses gradientes por meio de relações ecomorfológicas, uma vez que traços morfológicos e hábitos de girinos foram selecionados pela estratificação vertical gerada pela cobertura vegetal, e pela profundidade da água. Em geral, apresentamos um estudo sobre ecologia de assembleias que é relevante para a conservação, pois os resultados sugerem complementaridade biótica dentro de hábitats que raramente são considerados como unidades biogeográficas distintas das florestas de várzea circundantes. Abstract in Portuguese is available with online material.
... High heterogeneity of macrophytes is expected in lentic environments (Moura J unior et al. 2015) as oxbow lakes (Mormul et al. 2013). The habitat heterogeneity formed by v arzeas and macrophyte rafts maintain the biodiversity (Wittmann et al. 2006, von May & Donnelly 2009, Waldez et al. 2013, Upton et al. 2014, Ramalho et al. 2016; however, it is poorly known in terms of beta diversity. ...
... All indicator species of macrophyte rafts are small-bodied hylids (except for Boana raniceps occurring in macrophyte rafts with emergent vegetation) and with similar ecological characteristics (Neckel-Oliveira et al. 2013). Hylids are predominant in the Neotropics due to the high taxonomic and ecomorphological diversity (Duellman 1999, Wiens et al. 2011), a pattern observed at the local scale in v arzeas and macrophyte rafts (H€ odl 1977, Hoogmoed 1993, Waldez et al. 2013, Upton et al. 2014, Ramalho et al. 2016. These species use floating vegetation for breeding, sheltering, foraging, and dispersal (H€ odl 1977, Hoogmoed 1993, Schiesari et al. 2003, Henning & Schirato 2006, Upton et al. 2014. ...
... Hylids are predominant in the Neotropics due to the high taxonomic and ecomorphological diversity (Duellman 1999, Wiens et al. 2011), a pattern observed at the local scale in v arzeas and macrophyte rafts (H€ odl 1977, Hoogmoed 1993, Waldez et al. 2013, Upton et al. 2014, Ramalho et al. 2016. These species use floating vegetation for breeding, sheltering, foraging, and dispersal (H€ odl 1977, Hoogmoed 1993, Schiesari et al. 2003, Henning & Schirato 2006, Upton et al. 2014. Therefore, ecologically similar and phylogenetically closelyrelated anurans co-occur in macrophytes rafts through environmental niche segregation (species sorting processes, Winegardner et al. 2012), a signal of the diverse structure of macrophyte communities (Mormul et al. 2013, Upton et al. 2014. ...
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Beta diversity can provide insights into the processes that regulate communities subjected to frequent disturbances, such as flood pulses, which control biodiversity in floodplains. However, little is known about which processes structure beta diversity of amphibians in floodplains. Here, we tested the influence of flood pulses on the richness, composition, and beta diversity of amphibians in Amazonian floodplain environments. We also evaluated indicator species for each environment. We established linear transects in three environments: low várzea, high várzea, and macrophyte rafts. Species richness decreased and beta diversity increased according to the susceptibility of habitats to flood pulses. Indicator species differed among environments according to forest succession promoted by the flood pulse. The decrease in species richness between high and low várzea is due to non-random extinctions. The higher rates of species turnover between várzeas and macrophyte rafts are driven by the colonization of species adapted to open areas. Our results highlight that the maintenance of complex environments is needed to protect biodiversity in floodplains.
... Then the otherwise floating plants be-come terrestrial until the water level rises again (Junk 1970, 1973, 1997, Junk et al. 1989, Goulding et al. 2003, Kricher 2011. However, floating meadows can be locally present for 9-12 months, as for instance observed by Upton (2015) in the Pacaya-Samiria Reserve, Peru. This seemed to be dependent on the yearly flood pulse and how severe flood levels were. ...
... Numerous anuran species have been reported from floating meadows, sometimes in remarkable densities. Several of them exploit these plant formations for reproduction, as calling activity, egg clutches and tadpoles (in the submerged root systems) have been frequently found (Hödl 1977, Schiesari et al. 2003, Upton 2015. Other species are rare, show no reproductive activity and sometimes their occurrence is apparently due to 'accidental' dispersal (Hödl 1977, Hoogmoed 1993, Upton et al. 2014. ...
... Hoogmoed (1993) provided lists of species found in floating meadows in Suriname, Bolivia and on the lower Amazon River in Brazil. Investigating floating meadow amphibians of the Upper Amazon River in Peru, Upton et al. (2011Upton et al. ( , 2014 and Upton (2015) described community structure, seasonal change and other life-history aspects. ...
Article
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Anuran amphibians are a key group when assessing diversity patterns in Amazonia. Of the many different habitat types in this region exploited by anurans, floating meadows have received little attention. These are semi-anchored, thick plant mats on the surface of water bodies. We characterize the diversity of anuran communities encountered in this habitat and explore the Amazon River species turnover. Thirty-five species were recorded at seven floating meadow sites. Species richness varied among them but similarity was commonly high between neighbouring floating meadows. Upper Amazon basin sites were more similar to each other than to central Amazonian sites. Central Amazonian sites had limited similarity to each other. High densities in certain anuran species suggest that floating meadows provide highly beneficial habitats, while the presence of other, less common species may result from ‘accidental’ drift. Yet anuran beta-diversity is relatively similar. We suggest that this is likely due to the fluid nature of floating meadows, which have the ability to disperse anurans. © 2017 Deutsche Gesellschaft für Herpetologie und Terrarienkunde e.V. (DGHT), Mannheim, Germany.
... Heavy flooding and high winds during Hurricane Katrina likely damaged chorus frog habitat and may have forced individuals to move from highly impacted areas. Rain and flooding have also been implicated in increasing anuran dispersal by allowing macrophyte rafting along and across rivers, which can cause abnormally long-distance dispersal (Schiesari et al. 2003;Upton et al. 2014). Macrophyte rafts can also serve as suitable temporary habitat during times when terrestrial habitat is flooded, allowing genetic material to be exchanged through the zone more rapidly (Schiesari et al. 2003;Upton et al. 2014). ...
... Rain and flooding have also been implicated in increasing anuran dispersal by allowing macrophyte rafting along and across rivers, which can cause abnormally long-distance dispersal (Schiesari et al. 2003;Upton et al. 2014). Macrophyte rafts can also serve as suitable temporary habitat during times when terrestrial habitat is flooded, allowing genetic material to be exchanged through the zone more rapidly (Schiesari et al. 2003;Upton et al. 2014). ...
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Although theory suggests that hybrid zones can move or change structure over time, studies supported by direct empirical evidence for these changes are relatively limited. We present a spatiotemporal genetic study of a hybrid zone between Pseudacris nigrita and P. fouquettei across the Pearl River between Louisiana and Mississippi. This hybrid zone was initially characterized in 1980 as a narrow and steep "tension zone," in which hybrid populations were inferior to parentals and were maintained through a balance between selection and dispersal. We reanalyzed historical tissue samples and compared them to samples of recently collected individuals using microsatellites. Clinal analyses indicate that the cline has not shifted in roughly 30 years but has widened significantly. Anthropogenic and natural changes may have affected selective pressure or dispersal, and our results suggest that the zone may no longer best be described as a tension zone. To the best of our knowledge, this study provides the first evidence of significant widening of a hybrid cline but stasis of its center. Continued empirical study of dynamic hybrid zones will provide insight into the forces shaping their structure and the evolutionary potential they possess for the elimination or generation of species.
... Thus, to understand their general patterns of spatial occurrence in these flooded habitats, as well as their variation within the different várzea habitats, we compiled species lists based on our primary data from these habitats at the Solimões and Negro River basins since 2001. We expanded these species lists with secondary data from local/regional inventories focused on flooded habitats or that explicitly discriminated where species were recorded (Hödl, 1977;Hoogmoed, 1993;Schiesari et al., 2003;Gordo, 2003;Neckel-Oliveira and Gordo, 2004;von May et al., 2010;Pantoja and Fraga, 2012;Bernarde et al., 2013;Waldez et al., 2013;Barros et al., 2014;Upton et al., 2014;Moraes et al., 2016;Ramalho et al., 2016;Böning et al., 2017;Debien et al., 2019). To avoid bias considering species with historical gaps in their taxonomic and distributional resolutions, we kept them in broader taxonomic categories. ...
Chapter
The species richness inhabiting wetlands increases in tropical regions, following the broadly recognized pattern of increase in overall species richness from high latitudes to the Equator. In tropical South America, a dynamic seasonally flooded wetland system develops on the margins of large Amazonian rivers. A unique biota occupies these river-created habitats, contributing to the high species richness known for this bioregion. Amphibians and squamates are highly diverse vertebrates occupying these Amazonian flooded habitats, and show remarkable adaptations to inhabit them, such as an external morphology well suited to swimming ability, and temporal synchronicity of their life cycles with seasonal flooding. However, overall diversity and spatial structuring of amphibian and squamate assemblages in these flooded habitats are poorly characterized and wait a knowledge summary. Here, we combine previous knowledge with novel data on species occurrence to summarize and investigate the amphibian and squamate species diversity in Amazonian flooded habitats, considering two distinct geographic scales. Therefore, this chapter is structured in two main sections; in the first one we explore the origins of Amazonian flooded habitats, and how their dynamics and structural characteristics lead to the occurrence of a distinct biota of amphibians and squamates. In the second section, we present a case study on the longitudinal variation of species richness and composition of amphibian assemblages in these habitats along one of the largest Amazonian rivers, in Brazil.
... Thus, to understand their general patterns of spatial occurrence in these flooded habitats, as well as their variation within the different várzea habitats, we compiled species lists based on our primary data from these habitats at the Solimões and Negro River basins since 2001. We expanded these species lists with secondary data from local/regional inventories focused on flooded habitats or that explicitly discriminated where species were recorded (Hödl, 1977;Hoogmoed, 1993;Schiesari et al., 2003;Gordo, 2003;Neckel-Oliveira and Gordo, 2004;von May et al., 2010;Pantoja and Fraga, 2012;Bernarde et al., 2013;Waldez et al., 2013;Barros et al., 2014;Upton et al., 2014;Moraes et al., 2016;Ramalho et al., 2016;Böning et al., 2017;Debien et al., 2019). To avoid bias considering species with historical gaps in their taxonomic and distributional resolutions, we kept them in broader taxonomic categories. ...
Chapter
Aim: The main focus of this chapter is to provide a brief overview on global patterns of diversity and conservation of wetlands herpetofauna and discuss both ecological and morphological adaptations that facilitate life in such environments. By treating Amazonian wetland amphibians and reptiles as our case studies, we examine their level of specificity to wetland use and current conservation status. Snakes are evaluated in more detail to illustrate reptile diversity thriving in wetlands, which is not necessarily composed of species strictly adapted to water. Finally, both crocodilians and chelonians are considered as case studies to discuss how management initiatives have been linked to their current conservation status. Main concepts covered •Ecological and morphological adaptations of herpetofauna to wetland life. •Global diversity and conservation status of wetland amphibians and reptiles. •Level of specificity of Amazonian amphibian and reptiles to wetlands use. •Sustainable management initiatives for crocodilians and chelonians. Main methods covered: In this chapter, we present a thorough literature review of the current knowledge regarding the ecology and conservation of amphibians and reptiles occurring in wetlands. Overall, we use updated global IUCN Red List assessments to evaluate their global diversity and conservation status. Furthermore, we use more refined group-specific assessments when available (i.e. IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) for chelonians; Rhodin et al., 2018; Meiri, 2018; Uetz et al., 2020 for lizards and snakes). To a great extent, we focus on Neotropical herpetofauna, and specifically on some Amazonian species as case studies to exemplify broad ecological and morphological patterns. Conclusion/outlook: Most amphibian and reptile groups are well represented by wetland-dweller species and some groups show ecological and morphological adaptations to thrive in the water for at least some part of their lives. Broad patterns on the diversity and conservation status of wetland herpetofauna suggest that these animal groups depend mostly on habitat integrity and availability.
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Global biodiversity is currently facing the sixth mass extinction, with extinction rates at least 100 times higher than background levels. The Amazon Basin has the richest amphibian fauna in South America, but there remain significant gaps in our knowledge of the drivers of diversity in this region and how amphibian assemblages are responding to environmental change. Surveys were conducted in the Pacaya-Samiria National Reserve (PSNR) in Amazonian Peru, with a view to (1) comparing assemblage structure on floating meadows and adjacent terrestrial habitats; (2) determining the predictors of diversity in these habitats; and (3) exploring the effects of disturbance and seasonal flooding on diversity measures. Eighty-one species of amphibians have been recorded in these habitats since 1996 representing 11 families and three orders. In 2012-2013 22 anuran species used the floating meadow habitat, of which 10 were floating meadow specialists. These specialists were predominantly hylids which breed on floating meadows all the year round. Floating meadows therefore host an assemblage of species which is different to that found in adjacent terrestrial areas which are subject to seasonal flooding. Floating meadows enhance the amphibian diversity of the region, and rafts of vegetation that break away and disperse frogs downstream may explain the wide distribution of hylids within the Amazon Basin. Fourteen different reproductive modes were represented within the 54 anuran species observed. The number of reproductive modes present was influenced by localised disturbance and seasonal flooding. Diversity increased in the low water period, with hylids breeding in temporary pools. When the forest is inundated most species disperse away from the flood waters. Disturbance, habitat change, emerging diseases and climate change would likely lead to changes in species composition and assemblage structure rather than wholescale extinctions. However, further studies are needed to evaluate long-term consequences of synergistic environmental change.
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Despite the increasing amount of knowledge available regarding the ecological interactions between species, the dynamics of anurans in aquatic environments are little explored and understood. In this way, our work aims to assess which factors influence the composition and the ecological interactions of hylid anurans in oxbow lakes in the middle Purus River, Amazonas. We sampled three lakes with high, medium and low levels of connectivity twice, once during the flood and then in drought hydrological regimes. Variations in the hylid anuran assemblages and ecological interactions were tested as function of environmental niche, food resources, level of connectivity and hydrological regime. The availability of environmental resources and the availability of food resources were the best factors that explain the distribution of hylid anurans, which were also highly dependent on the variations between the hydrological regimes. The interactions between anurans, macroinvertebrates and macrophytes showed a modular and specialized structure, which varied according to the connectivity and hydrological regime of the lakes. Connectance showed an increasing trend from high to low connectivity lakes, suggesting that anurans had low trophic and environmental specialization in lakes with low connectivity. Hylids found in the lake of medium connectivity had higher values of trophic specialization and modularity. Our results illustrate the role of river-lake connectivity and annual hydrological cycle to maintain the aquatic biota and their interactions, and highlight the importance of floating meadows for the maintenance of biodiversity in floodplains.
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Upper Amazonian forests offer some of the highest species diversity in the world due in part to their complex habitats created by fluctuating water levels. In the Pacaya-Samiria National Reserve within the upper Amazonian forest of Peru, forty species of anuran belonging to seven families were recorded in 2009 and 2010 over forty survey days. A species accumulation curve indicated that most species present were detected after ten days of surveying. On land, frogs were most frequently observed among leaf litter. In the river, floating rafts of vegetation may be an important mechanism for the dispersal of frogs.
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The Amazon area, which for convenience’s sake is here considered to include the Guianas, and therefore could better be called the Central cis-Andean tropical lowlands (Hoogmoed 1979b; Lynch 1979), is renowned for the many rivers and the large volume of water (20% of the Earth’s freshwater) flowing through it. The water in this area can be divided into three classes (Junk 1983; Sioli 1984), viz.: (1) Black water has a dark brown colour, has a very low concentration of dissolved minerals, has no suspended particles and has a high acidity (pH 3.8-4.9), due to dissolved tannines leached out of leaflitter. Notable examples of black-water rivers are the Rio Negro in northern Brazil, draining the westernmost part of the Guiana Shield, and the creeks in the white sand Savanna Belt of the Guianas, of which one in Suriname is known as Cola Creek. (2) Clear water is greenish to transparent, with no suspended particles and a concentration of dissolved minerals that may range from very low to relatively high, and a pH that ranges between very acid and neutral (pH 4.57.8). Good examples are the Rio Tapajos and the Rio Xingu, and forest creeks in Suriname (witiewatra) south of the Savanna Belt. (3) White water has a milkish white to grey colour due to the suspended inorganic material, it is turbid and contains a relatively high concentration of dissolved minerals and has a pH of about 7 (6.2-7.2). Examples are the Rio Solimoes, the Rio Madeira, and in Suriname the lower courses of the larger rivers. .
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Large rivers have played a prominent role in biogeographic theory for their potential to act as barriers for the dispersal of terrestrial organisms,and therefore be involved in the generation of species diversity (Brown & Lomolino 1998). In this paper, we document the potential role of macrophyte rafts as a mechanism by which Amazonian rivers could act as dispersal agents rather than barriers, transferring organisms across banks and possibly across very large distances. These vectors could therefore act against speciation and towards homogenization of the local biota.
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Abundance and distribution of frogs inhabiting the litter layer of an area of primary lowland rain forest in Central Amazonia were studied over a period of 15 months by sampling 498 plots each 5m × 5m. The litter frog fauna of the area consists of 23 species, but only 12 of these were encountered in the plots, and 84% of the frogs encountered belonged to only six species. Total abundance and diversity within the plot data are strongly seasonal and peak in the late wet season. Both are positively correlated with litter volume and moisture. Most of this variation is due to seasonality of reproduction, as indicated by patterns of occurrence of juveniles of the most abundant species. These results indicate that the plot sampling method docs not sample the entire fauna adequately. Since this technique has been used to study other tropical forest litter herpetofaunas, however, comparison with other studies may be useful. Species diversity of litter frogs appears to be approximately the same in lowland primary forest sites studied, averaging around 20 ‘regular’ species. Abundances, however, vary widely. Central American communities contain 14–15 frogs (100m) ⁻² , African 9–10, South American 4–6, and South-east Asian 1–2. These differences may be due to differential nutrient availability in forests of different ages and/or on different soils.
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The acoustic behaviour of 15 sympatric and synchronically breeding species of frogs in an area of floating meadows near Manaus (Brazil) was studied for a period of 8 months. The calling positions of each species can be identified with certain physiognomic types of vegetation. Sound analyses were used to compare the mating calls. The main variables are dominant frequency, call duration and pulse repetition rate. Each of the 15 species has a distinct mating call and differs from the acoustic behaviour of each other one. Eleven species are separated in their dominant frequency ranges within their specific calling sites. Species sharing emphasised frequency ranges within identical calling sites differ greatly in at least two temporal variables. The roles of calling position, spectral, and temporal features of mating calls in species recognition and premating reproductive isolation are discussed.
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Macrophyte rafts can enhance fish dispersal in the Amazon River basin, and determining whether raft properties (e.g., size and plant species richness) can predict fish species richness and composition is important in order to understand the underlying factors of fish dispersal. We tested for a relationship between the plant species richness and fish species richness in the rafts and determined whether there exists a significant pattern of concordance between rafts composition and fish assemblages in a River–Lake system close to Manaus, Amazonas, Brazil. We estimated the cover of each species of macrophyte and collected fish in 20 macrophyte rafts of different sizes. Macrophyte species richness was not a good predictor of fish species richness. We found a significant correlation between the compositional similarities of macrophytes and fishes when the data for presence/absence were analyzed, but not when abundance data were used. However, the congruence patterns were clearly related to raft size, and we found a correlation between plants and fishes, using both presence/absence and abundance data, when only large rafts were used in the analysis. For small rafts, there were no significant correlations using any type of data. These findings show that the composition of fish assemblage dispersal in the rafts depends on the composition of macrophytes of which the rafts are composed and on stochastic processes of raft splitting. KeywordsDispersal vectors-Fish and macrophyte relationship-Ichthyofauna-Solimões River-Partial Mantel
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Neotropical aquatic ecosystems have a rich aquatic flora. In this report, we have listed the aquatic flora of various habitats of the upper Paraná River floodplain by compiling data from literature and records of our own continuous collections conducted during the period 2007-2009. Our main purposes were to assess the macrophyte richness in the Paraná floodplain, to compare it with other South American wetlands and to assess whether the number of species recorded in South American inventories has already reached an asymptote. We recorded a total of 153 species of macrophytes in the Upper Paraná River floodplain, belonging to 100 genera and 47 families. In our comparative analysis, a clear floristic split from other South American wetlands was shown, except for the Pantanal, which is the closest wetland to the Paraná floodplain and, therefore, could be considered a floristic extension of the Pantanal. The species accumulation curve provides evidence that sampling efforts should be reinforced in order to compile a macrophyte flora census for South America. The high dissimilarity among South American wetlands, together with the lack of an asymptote in our species accumulation curve, indicates that the sampling effort needs to be increased to account for the actual species richness of macrophytes in this region.
Amphibian Ecology and Conservation: A Hand-book of Techniques Cusco Amazonico: The Lives of Reptiles and Amphibians in an Amazonian Rainforest
  • K Dodd
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dodd, c. K. Jr. 2010. Amphibian Ecology and Conservation: A Hand-book of Techniques. Oxford University Press, Oxford. 556 pp. duellMan, W. e. 2005. Cusco Amazonico: The Lives of Reptiles and Amphibians in an Amazonian Rainforest. Cornell University Press, Ithaca, New York. 433 pp.
Floods of Fortune: Ecology and Economy along the Amazon 206 pp. hödl, W. 1977. Call differences and calling site segregation in anuran species from central Amazonian floating meadows
  • M J Goulding
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goulding, M., n. J. h. sMith, and d. J. Mahar. 1996. Floods of Fortune: Ecology and Economy along the Amazon. Columbia University Press, New York. 206 pp. hödl, W. 1977. Call differences and calling site segregation in anuran species from central Amazonian floating meadows. Oecologia 28:351–363.
Investigations on the ecology and production biology of the floating meadows (Paspalo echinochloetum) on the middle Amazon, part 1, the floating vegetation and its ecology
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Monographiae Biologicae No. 70. Springer, Netherlands. JunK, W. 1970. Investigations on the ecology and production biology of the floating meadows (Paspalo echinochloetum) on the middle Amazon, part 1, the floating vegetation and its ecology. Amazoniana 2:449-495.