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Ostracoda and Amphibia in temporary ponds: Who is the prey? Unexpected trophic relation in a mediterranean freshwater habitat

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Small and temporary freshwater ecosystems are important biodiversity “hot spots” of the Mediterranean region, and their food webs are considered as very complex systems. Amphibians and ostracods are two highly ubiquitous classes of metazoans adapted to live in temporary ponds. Their trophic interactions are considered unidirectional, the amphibians acting as predators and the ostracods as preys. In the field, we observed the opposite interaction in few ponds in Northern Italy. To confirm this qualitative evidence, we set up laboratory experiments to investigate the predation by the Ostracod mussel shrimp (Heterocypris incongruens) on eggs and tadpoles of Common toad (Bufo bufo) and Stripless tree frog (Hyla meridionalis). Amphibian eggs of both species were offered to ostracods either as unique trophic resource or, alternatively, together with another kind of food. Similarly, tadpoles of both species were simultaneously offered to ostracods (with alternative food) to disclose their preferences. Ostracods preyed mainly on amphibian eggs and no significant differences in the rate of predation between toad and treefrog eggs were detected. However, ostracods preferred Bufo when offered along with Hyla tadpoles. Toad eggs and larvae are commonly considered highly unpalatable, but our results contrasted this view. The difference in the predation rate between the two tadpole species is discussed in the light of their swimming behaviour. We show that feeding relationships between Amphibia and Ostracoda are much more complex than expected and depend on both the ecological context and amphibian life stage. The knowledge of the trophic connections among taxa is a fundamental prerequisite to further and more exhaustive studies on community ecology. KeywordsAmphibia–Ostracoda–Egg predation–Food web–Temporary ponds
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Aquatic Ecology
A Multidisciplinary Journal
Relating to Processes
and Structures at Different
Organizational Levels
ISSN 1386-2588
Volume 45
Number 1
Aquat Ecol (2010) 45:55-62
DOI 10.1007/s10452-010-9323-
Ostracoda and Amphibia in temporary
ponds: who is the prey? Unexpected
trophic relation in a mediterranean
freshwater habitat
1 23
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Ostracoda and Amphibia in temporary ponds: who
is the prey? Unexpected trophic relation in a mediterranean
freshwater habitat
Dario Ottonello Antonio Romano
Received: 8 November 2009 / Accepted: 5 May 2010 / Published online: 20 May 2010
ÓSpringer Science+Business Media B.V. 2010
Abstract Small and temporary freshwater ecosys-
tems are important biodiversity ‘‘hot spots’’ of the
Mediterranean region, and their food webs are con-
sidered as very complex systems. Amphibians and
ostracods are two highly ubiquitous classes of meta-
zoans adapted to live in temporary ponds. Their
trophic interactions are considered unidirectional, the
amphibians acting as predators and the ostracods as
preys. In the field, we observed the opposite interac-
tion in few ponds in Northern Italy. To confirm this
qualitative evidence, we set up laboratory experi-
ments to investigate the predation by the Ostracod
mussel shrimp (Heterocypris incongruens) on eggs
and tadpoles of Common toad (Bufo bufo) and
Stripless tree frog (Hyla meridionalis). Amphibian
eggs of both species were offered to ostracods either
as unique trophic resource or, alternatively, together
with another kind of food. Similarly, tadpoles of both
species were simultaneously offered to ostracods
(with alternative food) to disclose their preferences.
Ostracods preyed mainly on amphibian eggs and no
significant differences in the rate of predation between
toad and treefrog eggs were detected. However,
ostracods preferred Bufo when offered along with
Hyla tadpoles. Toad eggs and larvae are commonly
considered highly unpalatable, but our results con-
trasted this view. The difference in the predation rate
between the two tadpole species is discussed in the
light of their swimming behaviour. We show that
feeding relationships between Amphibia and Ostra-
coda are much more complex than expected and
depend on both the ecological context and amphibian
life stage. The knowledge of the trophic connections
among taxa is a fundamental prerequisite to further
and more exhaustive studies on community ecology.
Keywords Amphibia Ostracoda
Egg predation Food web Temporary ponds
Aquatic habitats may differ in productivity, resource
abundance and community composition (e.g. Polis
et al. 1997). Food webs are particularly complex in
large and permanent aquatic ecosystems (e.g. Belgrano
et al. 2005), although their complexity in small and
temporary ponds has been often underestimated (e.g.
Wilbur 1997; Urban 2007). In the Mediterranean
region, ephemeral aquatic habitats represent the very
large majority of freshwater ecosystems (Blondel and
Aronson 1999) and the temporary ponds (sensu De
Handling Editor: Piet Spaak.
D. Ottonello
Via San Domenico 200, 17027 Pietra Ligure (SV), Italy
A. Romano (&)
Dipartimento di Biologia, Universita
`di Roma ‘‘Tor
Vergata’’, Via della Ricerca Scientifica, 00133 Rome,
Aquat Ecol (2011) 45:55–62
DOI 10.1007/s10452-010-9323-y
Author's personal copy
Meester et al. 2005) may be collectively considered as
biodiversity ‘‘hot spots’’ (e.g. Ce
´ghino et al. 2008 and
references therein; Williams et al. 2004). In fact, they
harbour taxa of high conservation interest (Della Bella
et al. 2005; Griffiths 1997).
Ostracoda and Amphibia are two highly ubiquitous
classes of metazoans colonising an extremely wide
variety of freshwater environments (Balian et al. 2008;
Martens et al. 2008), included the temporary ponds
(Eitam et al. 2004; Griffiths 1997; Rossetti et al. 2006).
Ostracods, or mussel shrimps, display a variety of
feeding strategies as they can act as filter-feeders,
detrivores, herbivores and carnivores. Among freshwa-
ter ostracods, scavenging is the main form of carnivory,
while parasitism is the least common carnivorous habit.
Several feeding habits may be adopted by the same taxon
as complementary and opportunistic feeding strategies
(Bennett et al. 1997; Vannier et al. 1998; Wilkinson et al.
2007 and references therein). Amphibians are predators
at the adult stage, whereas their larvae may be carniv-
orous (salamanders, newts and caecilians, see Kupfer
et al. 2005 and references therein; but also some anuran
species: McDiarmid and Altig 1999), herbivorous,
detritivorous or omnivorous (in frogs, toads and tree-
frogs: McDiarmid and Altig 1999). In many ecosystems,
amphibians are the major predator of invertebrates and
algae consumers (Blaustein and Wake 1990; Wake
1991), representing, in turn, a rich trophic resource for
1990; Hayes and Jennin gs 1990) and, at least during their
egg or larval stages, for several invertebrates (Gunz-
burger and Travis 2005; Romano and Di Cerbo 2007).
In the field, we qualitatively observed an unex-
pected trophic relation between ostracods and amphib-
ians (eggs and larvae) where the first were the predator
and the second were the prey. These observations
suggested that mussel shrimps might prey on amphib-
ian eggs and tadpoles. To test this hypothesis, we
performed a set of laboratory experiments to attempt to
estimate the rate of predation, the species-specific
preference for eggs, and to assess whether amphibian
eggs were preyed also when predators were provided
with an alternative food.
Study area, materials and methods
The study area includes four temporary ponds located
in an abandoned limestone quarry at 280 m a.s.l near
Bergeggi (Liguria, North West Italy). The ponds
(30 m
each, maximum depth: 0.6 m) are artificial
and were created for amphibians conservation pur-
pose. The area is characterised by Mediterranean
climate and the pond hydroperiod may last from
October to June depending on precipitations. Quar-
rying activities were stopped in 1960 and since then
the area has been naturalised by grass and shrub
vegetation typical of the Mediterranean maquis.
The ostracod Heterocypris incongruens (Ramdohr
1808) is common in the four ponds where the
Balearic green toad Bufo balearicus Boettger 1880,
the Parsley frog Pelodytes punctatus (Daudin 1802)
and the Stripeless treefrog Hyla meridionalis Boett-
ger 1874, also breed. The Common toad Bufo bufo
(Linnaeus 1758) spawns in only one of these ponds
which was our study pond.
Fig. 1 Egg strings of Common toad (Bufo bufo)ina
temporary pond in Northern Italy were hardly attacked by
ostracods (Heterocypris incongruens) which preyed on the
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In March 2009, we observed that ostracod density
was very heterogeneous among different microhabi-
tats of the pond where B. bufo breeds. Swarms of
H. incongruens were concentrated around and on the
eggs strings of the Common toad (Fig. 1) and high
densities were recorded also upon small submerged
sprigs. We also observed that ostracods seemed to
have attacked some tadpoles (Fig. 2). In order to test
the hypothesis that H. incongruens might prey on
amphibian eggs and tadpoles, we set up several
laboratory experiments. Experiment 1 and 3 were
designed to estimate the rate of predation, Experiment
2 and 4 to assess whether amphibian eggs were preyed
also when predators were provided with an alternative
food, Experiment 5 and 6 to assess the species-specific
preference for eggs and tadpoles, respectively, Exper-
iment 7 was design to control for factor other than
predation on the deterioration of eggs.
For each experiment, Ostracods, eggs and larvae of
B. bufo and H. meridionalis, and several sprigs covered
by incrusting algae were collected by hand from the
study pond and carried in laboratory. At the time of
collection, pond water parameters were: tempera-
ture =15°C, pH =8.91, conductivity =302 lS/cm,
dissolved oxygen =152 ppm). In the lab, seven
aquaria (20 930 920 cm, for a total volume of
12 l) were filled with tap water and kept at constant
temperature (20°C). Tap water was left to stand for
24 h before the experiments began to allow evapora-
tion of the chlorine. In each experiment, we placed
amphibian eggs and ostracods in the same aquarium.
Ostracods were placed in the aquaria 2 h earlier than
amphibian eggs or tadpoles in order to allow for their
acclimatisation to experimental conditions. At the
beginning of the experiment, the tap water parameters
were: tempe rature =20°C, pH =8.44, conductivity =
169 lS/cm, dissolved oxygen =89 ppm. Aquaria were
not exposed to direct solar radiation. Given that
experiments were performed in April, photoperiod
may be considered homogenous (12 h light vs. 12 h
darkness). The difference between the initial number of
amphibian eggs and the final number of eggs was
considered as the number of preyed eggs. We used the
following combination of ostracods, eggs, larvae and
other vegetable food (i.e. sprigs, which were substituted
every 24 h to provide abundant availability of incrusting
Experiment 1 (Exp.1): 21 eggs of B. bufo were
placed in an aquarium with 300 ostracods.
Experiment 2 (Exp.2): 21 eggs of B. bufo were
placed in an aquarium with 300 ostracods and sprigs.
Experiment 3 (Exp.3): 20 eggs of H. meridionalis
were placed in an aquarium with 300 ostracods.
Experiment 4 (Exp.4): 20 eggs of H. meridionalis
were placed in an aquarium with 300 ostracods and
Experiment 5 (Exp.5): 21 eggs of B. bufo and 21
eggs of H. meridionalis were placed in the same
aquarium with 300 ostracods.
Experiment 6 (Exp.6): 12 tadpoles of B. bufo and 12
tadpoles of H. meridionalis were placed in the same
aquarium with 300 ostracods and sprigs. All tadpoles
were at Gosner stage 26-30 (sensu Gosner 1960).
Experiment 7 (Exp.7): especially given the amphib-
ian eggs may dissolved quickly under the action of
aquatic fungi (e.g. Kiesecker and Blaustein 1995), 15
toad eggs were placed in a box without ostracods or
sprigs to verify whether other factors could cause the
disappearing of amphibian eggs.
In experiments 1, 2, 3, 4 and 5, we recorded the
number of amphibian eggs every 12 h for a period of
7 days. In experiment 6 and 7, we recorded the number
of amphibian tadpoles or eggs only at the beginning
and at the end of the experiment (i.e. after 7 days).
In order to evaluate whether the difference in the
level of ostracod predation upon eggs or tadpoles in
the different experiments was statistically significant,
Fig. 2 A Common toad tadpole (Bufo bufo) preyed upon
ostracods (Heterocypris incongruens) as observed in a tempo-
rary ponds in Northern Italy
Aquat Ecol (2011) 45:55–62 57
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we processed the final results (i.e. the number of egg
remained in a couple of boxes, or in the same box in
the Exp.5 and Exp.6) with the Fisher’s exact test
using Statistica
ver. 5.0 (Statistica package, Statsoft
Inc., USA).
In particular, we tested the results of Exp.1
versus Exp.2 and Exp.3 versus Exp.4 to highlight
the possible preferences between amphibian eggs and
alternative food. We also tested the results of Exp.5
and Exp.6 to disclose preferences showed by ostrac-
ods between two sources of amphibian eggs (toad and
treefrog) as food.
In the control experiment (Exp.7), we did not observe
decreasing of amphibian egg number, as we did not
observe any difference in the number of live eggs
at the beginning and at the end of the treatment.
The rate of predation showed by ostracods versus
amphibian eggs, in different conditions, is reported in
Fig. 3. The number of common toad eggs preyed
upon by ostracods differed significantly if alternative
vegetable food was available (Exp.1 vs. Exp.2, two-
tailed Fisher’s exact test, P=0.009). Conversely, no
significant differences were detected when treefrog
eggs and alternative food were provided (Exp.3 vs.
Exp.4, two-tailed Fisher’s exact test, P=0.096).
Finally, if ostracods could choose between toad
and treefrog eggs, they did not show any feeding
preference (Exp.5, two-tailed Fisher’s exact test,
P=0.744). However, when they were provided
with tadpoles of B. bufo and H. meridionalis (plus
incrusted sprigs), ostracods preyed significantly more
on toad larvae than on treefrog larvae (Exp.6, two-
tailed Fisher’s exact test, P=0.005).
Experimental conditions
The use of tap water in our experiments could
influence the trophic behaviour of the ostracods.
However, organisms adapted to life in temporary
freshwater ponds, probably suffer in the slightest
degree for artificial changes of their aquatic mean
because they are well adapted to unpredictable and
fluctuating physical and chemical parameters (Lahr
1997). The mussel shrimp Heterocypris sp., in
particular, is highly tolerant to different environmen-
tal conditions, as expected in freshwater species with
a wide geographical distribution (Yılmaz and Ku
˘lu 2006). Furthermore, dechlorinated tap water
is often used for freshwater crustaceans (De Meester
and Dumont 1989; Hanazato and Ooi 1992; Oda et al.
2007) and tadpoles (e.g. Kiesecker et al. 1996;
Saidapur et al. 2009) in ecotoxicological and ecolog-
ical laboratory experiments. This suggests that the
use of tap water in our experiment did not alter
significantly the results.
Interactions between ostracods and amphibians
Amphibian eggs and larvae are eaten by a wide range
of specialised and occasional consumers. However,
no literature records include ostracods (Gunzburger
and Travis 2005; Romano and Di Cerbo 2007). Given
that in the control experiment (Exp. 7), the amphibian
eggs were not dissolved by fungi (egg number
remained unvaried), the decrease in amphibian eggs
observed in the experiments was because of predation
by Ostracods, confirming our field observations.
Freshwater ostracods usually prey small inverte-
brates (Deschiens et al. 1953; Deschiens 1954; Cohen
1982; Cohen and Kornicker 1987; Janz 1992).
Although swarms of freshwater ostracods on larger
animals have been recorded, in these cases, predation
was not observed. In fact, despite the high number of
ostracods observed on a single amphibian reported in
the literature, i.e. on specimens of Yellow bellied
toad (Bombina variegata), Smooth newt (Lissotriton
vulgaris) and Crested newt (Triturus cristatus; Seidel
1989), there was neither evidence that the ostracods
were attacking toads or newts nor evidence that they
could cause them injuries or death. Probably, ostrac-
ods were feeding on the amphibian skin secretions,
although the may use amphibians also for dispersion,
as suggested by Seidel (1989). However, in our field
observation, the tadpoles were completely immobi-
lised by ostracods (Fig. 2) and thus they were unable
to act as vector.
Morphological adaptation to scavenging, the most
common feeding strategy in the ostracod order Podo-
copa, includes the possession of powerful furcal rami
(also called uropod). Although the uropod is used for
locomotion, it may also have several major functions in
58 Aquat Ecol (2011) 45:55–62
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the feeding process, including holding on carcasses of
large animals and their cutting and dismembering
(Parker 1997). Coherently, H. incongruens often attacks
small invertebrates (Ganning 1971;Meisch2000)and
feeds on carcasses of water birds (Reichholf 1983)and
amphibians (D. Ottonello unpublished data).
Experiment 5
Toad eggs
Treefrog eggs
Exp. 3 vs Exp. 4
Exp. 3: treefrog eggs
Exp. 4: treefrog eggs and algae
Exp. 1 vs Exp. 2
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168
Exp.1: toad eggs
Exp.2: toad eggs and algae
0 12 24 36 48 60 72 84 96 108 120 132 144 156 168
Fig. 3 Histograms showing the initial number of amphibian eggs (Bufo bufo and Hyla meridionalis) in five experiments and their
decreasing due to predation by ostracods (Heterocypris incongruens). See the text for further details
Aquat Ecol (2011) 45:55–62 59
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Palatability of amphibian eggs
The eggs and larvae of the two amphibian species
chosen in our study are considered different in their
palatability. Eggs and tadpoles of Bufo are generally
considered to be unpalatable, in particular to many
vertebrates and invertebrates with chewing mouth
parts (e.g. Henrikson 1990; Licht 1968; but see also
the criticism to this consideration in Gunzburger and
Travis 2005), while eggs and larvae of Hyla are
unanimously considered palatable (e.g. Gunzburger
and Travis 2005; Heuesser 1970; Licht 1969;
McDiarmid and Altig 1999).
Henrikson (1990) found that the eggs of B. bufo
were palatable to invertebrate predators with sucking
mouth parts while tadpoles were attractive to most
predators. Although ostracods may be considered as
possessor of a chewing apparatus (Meisch 2000), our
results show that they were not repulsed by Common
toad eggs, embryos and tadpoles. Thus, early life
stages of Bufo were not found unpalatable at a higher
rate than other taxa, confirming earlier observations
by Gunzburger and Travis (2005).
Ostracods seemed to prefer toad tadpoles to treefrog
larvae. Woodward (1983) found that reduced mobility
of tadpoles lowers mortality risk from invertebrate
predators. However, Bufo and Hyla larvae, at the
development stages included in our study, have similar
mobility (Chovanec 1992). Conversely, locomotor
mode of Bufo tadpoles, which use the whole tail for
locomotion, could makes them easier detectable than
Hyla tadpoles, which move mainly the tail tip and
therefore move less water mass (Heyer et al. 1975;
Chovanec 1992).
Furthermore, there are other factors which may
contribute in determining the different predation level
suffered by tadpoles of these two amphibian species.
First of all, the frontal position of the eyes of Bufo
tadpoles allows a restricted visual field in comparison
with that of Hyla (see Arnold and Ovenden 2002).
Second, the toad tadpoles, in comparison with other
anuran species, exhibit lower manoeuvrability, lower
speed of swimming and lower predator avoiding
movement because they have less axial musculature
(Wassersug and von Seckendorf Hoff 1985; Saidapur
et al. 2009). Third, Bufo tadpoles prefer to swim in the
whole water column in contrast to Hyla larvae which
prefer water surface (see Chovanec 1992). Differently
to other anurans, B. bufo tadpoles lack constitutive
morphological defences against invertebrate preda-
tors, which are more dissuaded by morphological and
behavioural defences than by chemical deterrents
´lvarez and Nicieza 2006). Overall, ostracods, as
other aquatic invertebrate predators, seem to prefer
toad tadpoles to other anuran larvae, probably because
they are more easily detectable by mean of visual and
tactile stimuli.
The knowledge, although sometimes anecdotal, of a
trophic connection between two (or more) taxa, i.e.
nodes in the food web, is the fundamental prerequi-
site for further and more complex studies which
intend to understand community ecology. Recently
redefined food webs invalidated partially some earlier
generalisations showing that long food chain and
omnivory are common in food web structure (e.g.
Martinez 1991; Schmid-Araya et al. 2002).
The consumption of a given prey item depends by
the predator hunger level and by the availability of
alternative food (Gunzburger and Travis 2005).
Amphibian eggs and larvae could be considered an
alternative trophic resource for ostracods, if other type
of food is lacking. Although less amphibian eggs were
consumed when alternative trophic resource was
provided, in all tests that we carried out, a portion of
amphibian eggs was also eaten by ostracods. Presum-
ably, the prey–predator relationship we report here
cannot be merely considered as an occasional behav-
iour, but it is likely a widespread feeding strategy, at
least when ostracods and amphibians are abundant in
the same aquatic site.
Prey–predator interactions between Ostracoda and
Amphibia were so far considered unidirectional, with
ostracods relegated in the role of preys and amphib-
ians (both at larval and adult stages) in the role of
predators (e.g. Cicort-Lucaciu et al. 2005; Dutra and
Callisto 2005; Spencer and Blaustin 2001). However,
trophic web where ostracods and amphibians are
involved are proved to be more complex, and a
variety of feeding relationships between these taxa is
now reported. Ostracods may pass unharmed through
the amphibian gut (being eliminate in the faeces
and thus potentially colonising new habitats, see
Hartmann 1975; Lopez et al. 2002). Furthermore, we
report for the first time that they are able to behave
as active predators on amphibians. In freshwater
60 Aquat Ecol (2011) 45:55–62
Author's personal copy
ecosystems, the answer to the question ‘‘who is the
prey, Amphibia or Ostracoda?’’, is not straightfor-
ward and unambiguous.
Acknowledgments We would like to thank Fabrizio Oneto for
the help during field survey and Giampaolo Rossetti for the
taxonomic determination of ostracods and suggestions. Federico
Marrone, Antonio Ruggiero and Sebastiano Salvidio provided
useful suggestions and stimulating discussions. We are indebted
to Ylenia Chiari, Filippo Barbanera and Angelo G. Solimini
for the linguistic revision and for the critical reading of the
ms. Finally, we would like to thank two other anonymous
reviewers for their precious suggestions during the revision of
the manuscript.
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... Relationships with other species can contribute to this wide distribution (Fernandez et al., 2016) and one of these inter-specific relationships may be the predator-prey interactions. Various fish species (usually absent in temporary habitats), aquatic insects (especially Odonata larvae), and amphibians, have been recorded consuming H. incongruens (Havel et al., 1993;Johnson, 1995;Ottonello and Romano, 2011;Vandekerkhove et al., 2012). Other crustaceans, such as Decapoda, Copepoda and Amphipoda species, also prey on ostracods (Moguilevsky and Gooday, 1977). ...
... On the other side, H. incongruens occasionally has been observed attacking some macroinvertebrates, such as cladocerans, copepods, chironomids, oligochaetes (Liperovskaya, 1948;Ganning, 1971). A larger prey can also be on the menu, especially the frog eggs and sickly or injured animals (fish, amphibians, even the water birds) (Reichholf, 1983;Ottonello and Romano, 2011). In addition, cannibalism have been also reported in H. incongruens clonal females (Rossi et al., 2011). ...
In aquatic environments, chemical cues are very important for the perception of danger, especially when visibility is low. It is known that ostracods rely on chemical senses to detect predators, which is essential for survival. Occurrence of alarm signals in the surroundings can affect their activities and behaviour. The present study investigates if the non-marine ostracod Heterocypris incongruens (Crustacea: Ostracoda) can detect and react to chemical compounds derived from a predator (Triturus spp. larvae) and from injured conspecifics. Also, the study aims to investigate whether habitat-substrate selection is at play when the individuals are in potential danger. The obtained results indicate that predator-derived chemicals and conspecific alarm cues induce specific behavioural responses: forming of aggregations, reduction of locomotion or camouflaging. It is possible that H. incongruens rapidly evaluates environmental cues and modifies defensive strategies depending on the type of semiochemicals perceived.
... Amphibians are considered top predators in many ecosystems, including bromeliads, consuming a large variety of invertebrates (Ottonello and Romano, 2010). Among the invertebrates that can be found in bromeliads, there are the microcrustaceans ostracods (Crustacea: Ostracoda; commonly known as seed shrimps). ...
... It is a medium-sized microcrustacean and due to its low mobility and the isolation provided by the bromeliads, it depends on other animal groups such as amphibians, reptiles and small mammals to disperse (Lopez et al., 1999(Lopez et al., , 2002. Recent studies demonstrate that besides be attached to the skin of amphibians for transportation, i.e., phoresy (Araújo et al., 2019), they also act as predators of eggs of some anuran species (Ottonello and Romano, 2010). Nonetheless, publications about Elpidium are scarce and predominantly related to taxonomic aspects (Pereira, 2017). ...
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The marsupial frog Fritziana goeldii is an endemic species of Brazil with few aspects of its habits reported in the literature. In this work, we report for the first time the ingestion of Elpidium sp., an ostracod that lives in bromeliads which is known to use amphibians as vectors for phoresy, by F. goeldii. It is also the first time that this group is reported in the digestive tract of an adult amphibian.
... Most free-living freshwater ostracods consume mainly algae, cyanobacteria and organic detritus, but have also been reported to feed on bacteria, fungi, protozoans, plants and pollen, fallen leaves, rotifers, oligochaetes, nematodes, copepods, cladocerans, chironomids, mosquito larvae, gastropod larvae, amphibian eggs, fish fry, assorted dead animals and even other ostracods, including individuals of the same species (Liperovskaya, 1948;De Deckker ,1983;Strayer, 1985;Campbell, 1995;Fryer, 1997;Smith and Delorme, 2010;Gray et al., 2010;Ottonello and Romano, 2011;Rossi et al., 2011). Ostracods are not widely reported to directly Accepted Article ...
... Ostracods have been reported to prey on amphibian eggs and tadpoles, which most animals find unpalatable (Gray et al., 2010;Ottonello and Romano, 2011). This could potentially be another way ostracods affect the rice field environment, as amphibians act as biological controls on rice pests (Khatiwada et al., 2016). ...
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p class="Standard">Ostracods are very common in rice fields and they can have a significant influence on the rice field ecosystem. They can reach very high densities, often higher than other meiofauna, and their activities can have both positive and negative effects on rice harvests. They directly affect nutrient recycling through excretion, and indirectly by physically disturbing the soil and releasing minerals, thus improving rice growth. On the other hand, ostracods grazing on nitrogen-fixing cyanobacteria potentially reduce rice yields. Rice is a primary staple food for over half of the world’s population, and therefore ostracods can have a significant impact on human food supply. The origin of the rice field ostracod fauna is poorly known, but many rice field ostracods are considered invasive, especially in southern Europe, and from rice fields they have the potential to spread to surrounding natural habitats. Despite their invasive potential and ecological effects on the rice field ecosystem, very little is known about the diversity, ecology and impacts of rice field ostracods in many rice-producing countries. One hundred and ninety-two named ostracod species/subspecies have been reported from rice fields in 26 countries and states worldwide in the published literature; for over three-quarters of rice-producing countries, no data are readily available, and for most of the countries that have available data, diversity is clearly under-reported. Most species that have been documented from rice fields belong to the Cyprididae (78%), a family that makes up approximately 43% of the 2500+ non-marine ostracod species. A further six families (Candonidae, Darwinulidae, Entocytheridae, Ilyocyprididae, Limnocytheridae and Notodromadidae) form the remainder of rice field ostracods. Twenty-two percent of the species reported from rice fields are sexually reproducing, 18% have mixed reproduction, but are mostly asexual, and for 60% males are unknown, and are probably entirely asexually reproducing species. This review and checklist of rice field ostracods are presented to facilitate further research on this group in rice field habitats, research that is crucial for food security in many regions.</p
... Thus, with these results, for Chlamydotheca sp., our second hypothesis that in low concentrations, the test organisms would be generalists, is not fully supported. Studies on the predation behavior of ostracods are scarce, but they are known to prey on a wide range of organisms including Daphnia magna (Ottonello and Romano 2011) and other cladocerans, as well as copepods, ostracods, oligochaetes, and insect larvae (Ganning, 1971;Meisch, 2000;Wilkinson et al., 2007). The preference for the chironomid prey over the two crustacean preys may have been due to the same reasons as discussed above for T. cophisa. ...
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Predation is known to play a prominent role in maintaining ecosystem structure and functioning. Despite metals being known to potentially affect predation in aquatic ecosystems, few studies have been conducted, so far, with the aim of evaluating this interplay. In the present study, the effects of four metal salts (copper, cadmium, mercury, and manganese) on the feeding rates and food preference of the dragonfly Tramea cophisa and of the ostracod Chlamydotheca sp. were studied by performing laboratory ecotoxicity tests. Food preference was evaluated by offering four prey species to dragonfly nymphs and three to adult large ostracods. In general, the food preference of both predator species after being exposed to metal salts was not altered, compared with controls, but the feeding rate of T. cophisa decreased in comparison with controls, after exposure to each metal salt, except manganese. Contrastingly, predation rates of Chlamydotheca sp. increased after metal salt exposure. This difference in response can be explained by differences in life-history traits of these two organisms. Both species individuals preferred soft-bodied prey (Oligochaeta, Chironomidae) over water-dwelling crustaceans that are likely to be more difficult to prey upon. Tests evaluating the effects of metals and other chemicals on predation behavior may lead to a better understanding of biotic interactions that can be restricted by chemical stress, improving our understanding of possible food web disruptions underlying chemical stress.
... During aequicauda-intensively consumes zooplankton decreasing copepod abundance (Yemelyanova, Temerova, & Degermendzhy, 2002). Some other ostracod species are also characterized by the ability to provide predatory nutrition (Campbell, 1995;Ottonello & Romano, 2011;Wilkinson, Wilby, Williams, Siveter, & Vannier, 2007). ...
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Artemia spp. play a key role in hypersaline ecosystems. Artemia can live in a salinity range from 10 to 300–340 g l−1, but in water bodies where salinity is between 10–100 g l−1, it may be absent. Is Artemia absence in some Crimean lakes determined by the presence of predators or by salinity? To answer this question field long‐term and experimental data collected in the Crimean lakes were used. With the least probability, the populations of Artemia existed in the lakes with a salinity of up to 50 g l−1 or above 300 g l−1. Self‐reproducing Artemia populations (all age stages) were most likely (≥ 80% of occurrence) noted in the salinity range of 150–200 g l−1. Long‐term monitoring in two lakes showed that in different years, a significant negative correlation of Artemia abundance with the numbers of amphipod Gammarus aequicauda and ostracod Eucypris mareotica was found in both lakes. This correlation can be explained by ostracod and amphipod predation on Artemia. In years without predator populations, the number of Artemia was higher by several times. Experiments showed that these amphipods and ostracods consume brine shrimps of different developmental stages. There are at least twelve crustacean species, five insect species and two fish species, all listed in this paper, which inhabit Crimean hypersaline waters and can eat Artemia. Their predation on Artemia often is a main cause of its absence in salinity range from 10 to 150 g l−1.
... They prey on small crustaceans such as Cladocera, Copepoda as well as feed on carcasses of fish, water birds and amphibians (Ottonello and Romano, 2011). ...
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Evaluation of pond water after the culture of ostracods (Heterocypris incongruens): associating toxicity with risk assessment ABSTRACT: Protections of aquatic lives from pollution associated hazard are critical to the sustenance of fish pond ecosystem. To determine whether valuable substances such as pond water can pose unacceptable level of risk to fish is the purpose of this investigation. Research has shown that the adverse outcomes of life threatening conditions originate from micro-level events. The use of whole organisms was an alternative approach to integrate and understand the biological substances that can cause toxicity to aquatic organisms. In this research, In vivo Early Life Stage (ELS) testing was conducted on the whole organism in the pond water prior to the independent feeding of ostracod (Heterocypris incongruens). The growth inhibition was also studied to effectively monitor the onset of toxic metabolites in the stationary fish pond. For sampling purpose, fish pond water was collected for five different days after the replacement of old water. It was noted that no further serial dilution was done as the number of days were adopted as dilution one to dilution five. The fish pond has the dimensions of 10×8×7 m, containing 500 liters of water and 200 fish. Fish pond water samples collected from days 1-4 showed average mortality 42-47%, while day 5 showed 77% ostracods mortality rate. These results suggested that the onset of fish pond water toxicity starts from day 2-5. This implied that toxic metabolites in fish pond water at day five and over can progressively impaired the proper growth and development of fish and other lower organisms.
... It could also encompass the possibility of a concentrated food source in the mesocosm which would result in there being a higher count of organisms in the sample. Ostracods exhibit a complex predator- prey relationship with Amphibians ( Ottonello & Romano, 2011). Ostracods feed on Amphibian eggs while Amphibians feed on the Ostracods. ...
Technical Report
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This is the Interim Report of the Killarney Lake Remediation Project and covers the experimental work completed in the last six months as well as Lake monitoring data from 2016. Enclosures were used again this year to confirm results obtained in 2015 on phosphorus flux from sediment as well as Phoslock effectiveness for immobilizing that flux. These results were limited due to loss of enclosures from weather and leakage, but five enclosures gave reasonable results that confirm both P flux data from 2015 and the effectiveness of Phoslock in a hard water alkaline lake with rich organic sediment. Data was collected to measure total phosphorus flux from the sediment by sampling the water column, floating plants and biomass attached to the enclosure walls. This phosphorus budget allowed comparison between controls and treatments as well as results collected by similar means in 2015. There was very little difference between Controls and Phoslock treatment (3500 mg TP vs 2444 mg TP flux). Comparing 2015 with 2016 sediment P flux in enclosures indicated there was at least a 30% increase in TP release in 2016. No measured environmental parameter (temperature, pH, ORP) could account for this, although stronger correlations were found in bottom ORP/pH in the lake and channel in 2016.
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Despite their important role in supporting important ecosystem functions in tropical wetlands, explorative and taxonomical studies on tropical zooplankton are still limited, hampering accurate comparisons between biogeographical regions and different wetland types. With this review we integrated current knowledge on patterns of species richness and endemicity across tropical biogeographical regions, while also summarizing the most important characteristics of the ecology, life history and conservation aspects of rotifer, cladoceran, copepod and ostracod zooplankton groups. To the best of our information this is the first review covering all zooplankton at the scale of the tropical biogeographical regions which can serve as a base for needed future studies.
In this work, the ostracod Heterocypris incongruens(Ramdohr, 1808) was used to analyse three of its behavioural activities (feeding, swimming and resting) and its food preference. The majority of the individuals spent their time swimming. However, towards the end of the experiment, the number of individuals found feeding increased. The overall time spent feeding throughout the experiment was significantly longer than the time spent swimming and resting. Spinach was the most frequently used food, followed by mosquito larvae, Cyclops(plankton mix) and Spirulina mix. The retention time spent in the compartment containing spinach was also significantly longer than the time spent on all other items.
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Macroinvertebrates as food were recorded for three anurans tadpoles: Hyla saxicola (Bokermann, 1964) (Hylidae), Scinax machadoi (Bokermann & Sazima, 1973) (Hylidae), and Bufo rubescens (Lutz, 1925) (Bufonidae). These species are commonly found in the mountain streams at Serra do Cipó National Park, Minas Gerais State, Brazil. Tadpoles were collected in pools of second-order reach in Mascates stream and third and fourth order reaches of Indaiá stream from March-October, 2003. Biometrical data were recorded before dissecting each individual and a feeding importance index was estimated. Eight taxa of chironomids and three taxa of mayfly exuviae were found in the guts, but no significantly differences were found between tadpole species (ANOVA, p > 0.05). The results support the drift transport hypothesis that predicts that tadpoles commonly ingest suspended matter in lotic ecosystems, are generalist feeders, and macroinvertebrates are probably incidental ingested.
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Hatchlings of Rana utricularia, Scaphiopus holbrooki, Bufo americanus and Hyla chrysoscelis were introduced at the same relative abundances at a low or a high initial density. Competition determined survival, body size at metamorphosis, and length of larval period in high-density communities, which were food-limited. The predatory salamander Notophthalmus viridescens did not alter either the total number of metamorphs or their combined biomass in high-density communities, but the relative abundance of metamorphs was shifted as S. holbrooki, the competitive dominant, was selectively eaten. In low-density communities, predation decreased survival and biomass production of tadpoles, often to zero, in all species. Competition slowed growth and thus increased the risk of desiccation in high-density populations in drying ponds. Predation ameliorated the effects of competition, allowing survivors to grow rapidly enough to metamorphose before ponds dried. Survival of tadpoles to metamorphosis, body size at metamorphosis, and time of metamorphosis were determined in a complex way by interactions among all of the treatment effects and the life history characteristics of the 4 species.-from Author
Carnivory in modern ostracods takes the form of predation, scavenging and parasitism. In the fossil record, carnivory is difficult to prove without the fossilisation of diagnostic functional morphological features or the preservation of the intimate association between the ostracods and the carrion or prey. Six examples of putative carnivory are known in geological deep time, the most persuasive being scavenging myodocopes of Ordovician, Carboniferous and Triassic ages (Myodoprimigenia, Eocypridina and Triadocypris), where swarms of ostracods are found associated with carcasses, and the early Silurian Colymbosathon in which characteristic soft part anatomy is preserved. Other putative scavengers, such as late Jurassic Juralebris, are unlikely to be carnivorous.
Most crustaceans inhabiting temporary pools have resting stages that can remain dormant for many years. Only a fraction of the resting stages hatch each time the pool floods, as a safeguard against unpredictable events resulting in complete reproductive failure. There is likely to be a selective advantage in the ability of resting stages to respond to signals indicating likely environmental conditions and to adjust their hatching fraction in response. We examine whether such an ability exists in the resting stages (diapausing eggs) of the ostracod Heterocypris incongruens, which inhabits temporary freshwater pools in northern Israel. The active stages are subject in some seasons to predation by larvae of the fire salamander (Salamandra salamandra L.). We predicted that a lower fraction of H. incongruens eggs would hatch in water in which S. salamandra larvae had been kept than in water that had not contained S. salamandra larvae. We found no such effect. We discuss possible reasons for the absence of the expected response. A lower proportion of H. incongruens eggs hatched in water with higher conductivity. This may reduce the risk of active stages being killed by desiccation before being able to complete their life cycle.
The myodocopine furca is redefined as a composite of 3 or 4 highly sclerotized structures: furcal sclerites I and II, or I-III (basal sclerites), and the paired furcal lamellae. These components are connected to form the furcal complex. Furcal sclerite I bears the 'globus' (sclerotized ball) and paired 'radii' (sclerotized rods), termed herein. This study shows that the furca has several major functions in the feeding process of scavenging cypridinid (Myodocopina) ostracods, which include the cutting and holding of small food sections from an animal carcass, helping to hold the ostracod firmly in position on a carcass, and removing small fish scales. These functions are made possible by the rotation of the furca in an anterior-posterior vertical plane, the arrangement of the claws on each lamella, and by varying the angle between lamellae. The central adductor muscles allow areas of the carapace to open differentially. Thus, the body of the ostracod remains relatively well protected, even during the extension of body parts through the carapace aperture (the carapace may open only in the region necessary for this protrusion). The area of hardened body wall just anterodorsal to the furca in Myodocopina is termed the sclerosome and its functions probably include support for certain furcal muscles and protection of the body, exposed when the carapace valves are open. The basal furcal sclerites probably provide similar protection. The sclerosome has highly sclerotized longitudinal margins, forming the gird. The gird and the radii pivot on the Y-sclerites to form a fulcrum for vertical furcal movements in an anterior-posterior plane. The sclerosome is unique to Myodocopina.
The ovarian eggs of four species of Rana and one species of Hyla were offered as food to potential vertebrate and invertebrate predators of anuran eggs. The predators ate the eggs and suffered no obvious ill aftereffects, indicating that ranid and hylid eggs are palatable and nontoxic. Tests with Bufo eggs reconfirmed previous findings that they are unpalatable and toxic when ingested.
Several anuran species in central New Mexico have access to both permanent and temporary ponds yet typically use only one or the other pond type. Visual censuses of terrestrial predators and sweep samples of aquatic predators established that more individual terrestrial predators, more terrestrial predator species, and more individual aquatic predators per cubic metre exist in permanent than in temporary ponds, suggesting that predators may prevent temporary-pond species from using permanent ponds. Eight predator species consumed more temporary- than permanent-pond tadpoles in 17 of 20 pairwise choice experiments. Temporary-pond tadpoles were almost continually in motion, while permanent-pond tadpoles were almost always stationary. This differential movement may account for the vulnerability of temporary-pond tadpoles to predation. The nonrandom distribution of predators in this tadpole community and the inability of some tadpoles to avoid predation apparently restricts some anurans to temporary ponds.