Interesting articles about Anemone fish and their host anemones

[ThRoewer]

Mutualism with sea anemones triggered the adaptive radiation of clownfishes (full article)

Abstract

Background: Adaptive radiation is the process by which a single ancestral species diversifies into many descendants adapted to exploit a wide range of habitats. The appearance of ecological opportunities, or the colonisation or adaptation to novel ecological resources, has been documented to promote adaptive radiation in many classic examples. Mutualistic interactions allow species to access resources untapped by competitors, but evidence shows that the effect of mutualism on species diversification can greatly vary among mutualistic systems.
Here, we test whether the development of obligate mutualism with sea anemones allowed the clownfishes to radiate adaptively across the Indian and western Pacific oceans reef habitats.

Results: We show that clownfishes morphological characters are linked with ecological niches associated with the sea anemones. This pattern is consistent with the ecological speciation hypothesis. Furthermore, the clownfishes show an increase in the rate of species diversification as well as rate of morphological evolution compared to their closest relatives without anemone mutualistic associations.

Conclusions: The effect of mutualism on species diversification has only been studied in a limited number of groups. We present a case of adaptive radiation where mutualistic interaction is the likely key innovation, providing new insights into the mechanisms involved in the buildup of biodiversity. Due to a lack of barriers to dispersal, ecological speciation is rare in marine environments. Particular life-history characteristics of clownfishes likely reinforced reproductive isolation between populations, allowing rapid species diversification.

Keywords: Ecological speciation, Diversification, Comparative method, Evolutionary rate, Brownian Motion, Pomacentridae

Very interesting read! I recommend to download the article as long as it is up for free.

The genetic relation tree that also includes the rest of the damsel fish indicates that quite a few are put into the wrong genus.

It also indicates that A. latezonatus is the oldest of all clownfish species, followed by P. biaculeatus and the percula/ocellaris branch.

 

[ThRoewer]

Ocean acidification impairs olfactory discrimination and homing ability of a marine fish

Abstract (full text)

The persistence of most coastal marine species depends on larvae finding suitable adult habitat at the end of an offshore dispersive stage that can last weeks or months. We tested the effects that ocean acidification from elevated levels of atmospheric carbon dioxide (CO2) could have on the ability of larvae to detect olfactory cues from adult habitats. Larval clownfish reared in control seawater (pH 8.15) discriminated between a range of cues that could help them locate reef habitat and suitable settlement sites. This discriminatory ability was disrupted when larvae were reared in conditions simulating CO2-induced ocean acidification. Larvae became strongly attracted to olfactory stimuli they normally avoided when reared at levels of ocean pH that could occur ca. 2100 (pH 7.8) and they no longer responded to any olfactory cues when reared at pH levels (pH 7.6) that might be attained later next century on a business-as-usual carbon-dioxide emissions trajectory. If acidification continues unabated, the impairment of sensory ability will reduce population sustainability of many marine species, with potentially profound consequences for marine diversity.

Blog-article based on this research paper:
Losing Nemo "“ acid oceans prevent baby clownfish from finding home

 

[ThRoewer]

Sound Production in the Clownfish Amphiprion clarkii (full article)

If you ever wondered how they make that noise...

 

[DanDashO]

Thanks for sharing! I was actually wondering about the evolutionary tree of damselfish just yesterday. I would have thought that clowns and dascyllus were more closely related...

 

[ThRoewer]

... I would have thought that clowns and dascyllus were more closely related...

Me too! I was kind of surprised.

But there are other surprising things that hint that there may be a revision required of which species belongs to which genus.

And I would hope they would finally do away with Premnas as a separate genus.

 

[Sk8r]

I have a dascyllus damsel (golden domino) that 'talks' frequently---or began to after she reached a certain size. Her type also will apparently set up shop in an anemone, not just in pairs, but in groups.

 

[ThRoewer]

Reproductive behavior of the anemonefish Amphiprion clarkii at Miyake-Jima, Japan (full article)

Coexistence of two anemonefishes, Amphiprion clarkii and A. perideraion, which utilize the same host sea anemone (full article)

Synopsis
Social structure and interactions between the anemonefishes, Amphiprion clarkii and A. perideraion, which utilize the same host sea anemone Radianthus kuekenthali, were investigated on a coral reef of Okinawa Islands, Japan. In an 87 x 373 mz study area, 98 sea anemones were inhabited by both species (32 .5 %), by only A. clarkii (48 .9%), or by only A. perideraion (18.6%). A group of A. clarkii often occupied two or more individual hosts, and group members often interchanged . However, a group of A. perideraion usually used only one host and migration between groups was rare. The larger A. clarkii suppressed reproduction of A. perideraion in cohabiting groups, while A. perideraion suppressed settlement of juvenile A. clarkii to its own hosts . Juvenile A. clarkii settled on small hosts as well as on large hosts, whereas juvenile A. perideraion settled only on large hosts . Coexistence appears to be possible in part by differences in settlement patterns between juveniles of the two anemonefishes .

Amphiprion clarkii Juvenile: Innate Protection against and Chemical Attraction by Symbiotic Sea Anemones (full article)

 

[CoralsAddiction]

Here's a very good video example of the study above.
https://www.youtube.com/watch?v=cdoSWr5Lg04

 

[ThRoewer]

Phylogeographic structure of false clownfish, Amphiprion ocellaris, explained by sea level changes on the Sunda shelf (full PDF)

Unfortunately the black Darwin clowns were not part of this sampling.
But the provided current charts show that the currents between Timor and Darwin wouldn't allow larva exchange between their range and that of A. ocellaris.
The plot thickens - it's only a matter of time until they get recognized as a distinct species.

 

[ThRoewer]

Some interesting articles about collection of clownfish and their host anemones:

Socio-economy of marine ornamental fishery and its impact on the population structure of the clown anemonefish Amphiprion ocellaris and its host anemones in Spermonde Archipelago, Indonesia (full PDF)

Population impacts of collecting sea anemones and anemonefish for the marine aquarium trade in the Philippines (full PDF)

 

[ThRoewer]

Embryonic learning of chemical cues via the parents' host in anemonefish (Amphiprion ocellaris) (Full PDF here)

Abstract

The species-specific host-recognition system of anemonefish was examined experimentally, with a particular focus on the function of imprinting using naive Amphiprion ocellaris juveniles. Anemonefish parents lay their eggs very close to their host anemone so the eggs are almost always touched by the host's body or tentacles. Here, we demonstrate the embryonic and immediate post-hatching learning of chemical cues via the parents' host in A. ocellaris through a host-exchange experiment with egg batches during hatching. The memory obtained from such imprinting operates at the time when juveniles first search for their hosts. Unexpectedly, innate recognition was found to exist not only in the symbiotic host species but also weakly in two non-partner species. Innate recognition alone is not sufficient. Imprinting via the parents' host complements innate recognition, leading to rigid species-specific host recognition. Imprinting by the parents' single host provides a sufficient cue for reaching the two host species. Furthermore, when combined with imprinting, innate recognition of non-partners serves to supplement the recognition of those species, leading to substitute partnerships that are only observed in some localities. Potential functions of imprinting in the host-recognition system are discussed. The "œspare recognition hypothesis" and the necessity of clear distinctions between symbiotic and substitute species are also proposed here.

 

[DanDashO]

Interesting articles about Anemone fish and their host anemones

I was hoping you would share this article So in theory, we could make captive bred clowns accepting of all host anemones, assuming their parents could be made to accept an unnatural host.

 

[ThRoewer]

I think that should work.
It would likely also account for the mixed experiences many have with tank raised clowns. Many hobby breeders keep their pairs in anemones, mostly BTAs, while most commercial breeders don't do that due to cost and added complications.

 

[ThRoewer]

Some info and articles I poster earlier here: Clownfish larva cognition and learning
I think it is best to combine it all into one thread.

Fish Cognition and Behavior.
Quite interesting and from the bits I've read so far fish are not as simple minded as many may think. Their brains are capable of quite some tasks and some have incredible long term memory.
They also have clearly individual personalities.

It turns out that many reef fish larva - among them clownfish larva - usually stay close and settle near their birth site/reef. Genetic sampling has shown this.
It also seems the larva learn the chemical signature of their parents anemone species while still in the egg and look for this when settling down.
Another suspicion is that they actually memorize the sounds of their home reef and use that to make sure to settle close to home. This is currently under investigation.

To me this explains a lot.
For example why many tank bred clowns are not so conditioned to certain anemones but are a bit more flexible. It may also explain why some have a hard time getting the idea of going into an anemone in the first place. They never learned it.

Interesting research on Amphiprion percula larva dispersal:

Larval dispersal connects fish populations in a network of marine protected areas

Abstract
Networks of no-take marine protected areas (MPAs) have been widely advocated for the conservation of marine biodiversity. But for MPA networks to be successful in protecting marine populations, individual MPAs must be self-sustaining or adequately connected to other MPAs via dispersal. For marine species with a dispersive larval stage, populations within MPAs require either the return of settlement-stage larvae to their natal reserve or connectivity among reserves at the spatial scales at which MPA networks are implemented. To date, larvae have not been tracked when dispersing from one MPA to another, and the relative magnitude of local retention and connectivity among MPAs remains unknown. Here we use DNA parentage analysis to provide the first direct estimates of connectivity of a marine fish, the orange clownfish (Amphiprion percula), in a proposed network of marine reserves in Kimbe Bay, Papua New Guinea. Approximately 40% of A. percula larvae settling into anemones in an island MPA at 2 different times were derived from parents resident in the reserve. We also located juveniles spawned by Kimbe Island residents that had dispersed as far as 35 km to other proposed MPAs, the longest distance that marine larvae have been directly tracked. These dispersers accounted for up to 10% of the recruitment in the adjacent MPAs. Our findings suggest that MPA networks can function to sustain resident populations both by local replenishment and through larval dispersal from other reserves. More generally, DNA parentage analysis provides a direct method for measuring larval dispersal for other marine organisms.


Persistence of self-recruitment and patterns of larval connectivity in a marine protected area network

Abstract
The use of marine protected area (MPA) networks to sustain fisheries and conserve biodiversity is predicated on two critical yet rarely tested assumptions. Individual MPAs must produce sufficient larvae that settle within that reserve's boundaries to maintain local populations while simultaneously supplying larvae to other MPA nodes in the network that might otherwise suffer local extinction. Here, we use genetic parentage analysis to demonstrate that patterns of self-recruitment of two reef fishes (Amphiprion percula and Chaetodon vagabundus) in an MPA in Kimbe Bay, Papua New Guinea, were remarkably consistent over several years. However, dispersal from this reserve to two other nodes in an MPA network varied between species and through time. The stability of our estimates of self-recruitment suggests that even small MPAs may be self-sustaining. However, our results caution against applying optimization strategies to MPA network design without accounting for variable connectivity among species and over time.


Are clownfish groups composed of close relatives? An analysis of microsatellite DNA variation in Amphiprion percula

Abstract
A central question of evolutionary ecology is: why do animals live in groups? Answering this question requires that the costs and benefits of group living are measured from the perspective of each individual in the group. This, in turn, requires that the group's genetic structure is elucidated, because genetic relatedness can modulate the individuals' costs and benefits. The clown anemonefish, Amphiprion percula, lives in groups composed of a breeding pair and zero to four nonbreeders. Both breeders and nonbreeders stand to gain by associating with relatives: breeders might prefer to tolerate nonbreeders that are relatives because there is little chance that relatives will survive to breed elsewhere; nonbreeders might prefer to associate with breeders that are relatives because of the potential to accrue indirect genetic benefits by enhancing anemone and, consequently, breeder fitness. Given the potential benefits of associating with relatives, we use microsatellite loci to investigate whether or not individuals within groups of A. percula are related. We develop seven polymorphic microsatellite loci, with a number of alleles (range 2"“24) and an observed level of heterozygosity (mean = 0.5936) sufficient to assess fine-scale genetic structure. The mean coefficient of relatedness among group members is 0.00 ± 0.10 (n = 9 groups), and there are no surprising patterns in the distribution of pairwise relatedness. We conclude that A. percula live in groups of unrelated individuals. This study lays the foundation for further investigations of behavioural, population and community ecology of anemonefishes which are emerging as model systems for evolutionary ecology in the marine environment.


Probability of successful larval dispersal declines fivefold over 1 km in a coral reef fish

Abstract
A central question of marine ecology is, how far do larvae disperse? Coupled biophysical models predict that the probability of successful dispersal declines as a function of distance between populations. Estimates of genetic isolation-by-distance and self-recruitment provide indirect support for this prediction. Here, we conduct the first direct test of this prediction, using data from the well-studied system of clown anemonefish (Amphiprion percula) at Kimbe Island, in Papua New Guinea. Amphiprion percula live in small breeding groups that inhabit sea anemones. These groups can be thought of as populations within a metapopulation. We use the x- and y-coordinates of each anemone to determine the expected distribution of dispersal distances (the distribution of distances between each and every population in the metapopulation). We use parentage analyses to trace recruits back to parents and determine the observed distribution of dispersal distances. Then, we employ a logistic model to (i) compare the observed and expected dispersal distance distributions and (ii) determine the relationship between the probability of successful dispersal and the distance between populations. The observed and expected dispersal distance distributions are significantly different (p < 0.0001). Remarkably, the probability of successful dispersal between populations decreases fivefold over 1 km. This study provides a framework for quantitative investigations of larval dispersal that can be applied to other species. Further, the approach facilitates testing biological and physical hypotheses for the factors influencing larval dispersal in unison, which will advance our understanding of marine population connectivity.


This one is on A. clarkii:
USING ISOLATION BY DISTANCE AND EFFECTIVE DENSITY TO ESTIMATE DISPERSAL SCALES IN ANEMONEFISH

Abstract
Robust estimates of dispersal are critical for understanding population dynamics and local adaptation, as well as for successful spatial management. Genetic isolation by distance patterns hold clues to dispersal, but understanding these patterns quantitatively has been complicated by uncertainty in effective density. In this study, we genotyped populations of a coral reef fish (Amphiprion clarkii) at 13 microsatellite loci to uncover fine-scale isolation by distance patterns in two replicate transects. Temporal changes in allele frequencies between generations suggested that effective densities in these populations are 4"“21 adults/km. A separate estimate from census densities suggested that effective densities may be as high as 82"“178 adults/km. Applying these effective densities with isolation by distance theory suggested that larval dispersal kernels in A. clarkii had a spread near 11 km (4"“27 km). These kernels predicted low fractions of self-recruitment in continuous habitats, but the same kernels were consistent with previously reported, high self-recruitment fractions (40"“60%) when realistic levels of habitat patchiness were considered. Our results suggested that ecologically relevant larval dispersal can be estimated with widely available genetic methods when effective density is measured carefully through cohort sampling and ecological censuses, and that self-recruitment studies should be interpreted in light of habitat patchiness.

 

[ThRoewer]

Let's add this one here as well:

Modes of reproduction in sea anemones (Cnidaria, Anthozoa)

Abstract
The data on different modes of reproduction in sea anemones are generalized. These animals can reproduce sexually in an ordinary way or by parthenogenesis. Asexual reproduction occurs in various forms, such as transverse and longitudinal fission, pedal laceration, or autotomy of tentacles. Specific features of different variants of sexual and asexual reproduction and their combinations in sea anemones from different habitats of the World Ocean are discussed.

Keywords: Cnidaria, sea anemones, sexual reproduction, parthenogenesis, asexual reproduction.

 

[ThRoewer]

Molecular ecology and evolution of anemonefishes (Amphiprion spp) in the Indo-Malay Archipelago (Dissertation - Full PDF)

Summary

The Indo-Malay Archipelago, located between the Pacific and Indian Ocean comprises the
world’s richest marine shallow water biodiversity. The development of the high biodiversity
in this region is discussed on the base of three different theories, the (1) “centre of
accumulation”, (2) “centre of overlap”, and (3) “centre of origin” theory. The area consists of
thousands of islands and peninsulas of different size, shape, and geological origin resulting in
a high complexity. Furthermore, it has large shallow shelf areas, offering potentially large
shallow water habitat to evolve, e.g. coral reefs. In times of sea level low stands during glacial
epochs, these areas were above sea level, leading to the loss and fragmentation of habitat for
shallow water communities. This separation of ocean basins triggered differentiation in
marine organisms, even leading to speciation.
In this thesis, genetic differentiation processes on different levels were studied in the genus
Amphiprion. This genus comprises anemonefish species, living in close symbiosis with sea
anemones, on which they depend for protection.
As many coral reef fishes, the anemonefishes are distinguished mainly by morphology and
colour patterns, although several species have quite similar colouration and some overlapping
morphological characters, making differentiation difficult. Two species complexes of the
subgenera Actinicola (A. ocellaris, and A. percula) and Phalerebus (A. akallopisos,
A. sandaracinos, A. perideraion) were investigated to reveal species boundaries and evaluate
speciation processes in the Indo-Malay Archipelago. The phylogenetic analyses were based
on mitochondrial cytochrome b (cyt b) and control region (CR) sequences.
The two studied species complexes showed differences in their patterns of species boundaries
despite the fact of belonging to the same genus as well as having a similar biology. Within the
subgenus Actinicola, five clades were found, representing different geographical regions. Two
major divergences indicated three instead of two deep evolutionary lineages, evolved in the
Pliocene. That time period was characterised by oscillations in climate with various small
glacial epochs, leading to fluctuations of the sea level. These intermediate disturbances for
shallow water communities might have provoked conditions for enhanced diversification in
the Indo-Malay Archipelago. Within the subgenus Phalerebus, three clades were revealed, not
correlated to certain geographical regions, but concordant to the morphological species
classification. Based on molecular clock calculations, these species separated in the time
range bordering the Pliocene and Pleistocene, when increased glacier formation led to further
sea level lowering, separating the Indian from the Pacific Ocean and possibly other sea areas
within the archipelago.
To investigate differentiation patterns on the intra-specific level, analyses of the genetic
population structure of the species A. ocellaris were conducted. A. ocellaris has a high
potential of population structuring, because it has demersal eggs, a short larval stage of only
8-12 days, and a very site-attached behaviour of the adults. Additionally, it is a very popular
marine aquarium fish, caught in high numbers from coral reefs, and therefore of commercial
value. For the analyses on population level, sequences of A. ocellaris from different locations
across the Indo-Malay Archipelago of a CR fragment were used as well as six microsatellite
loci.
Both marker systems revealed strong population structuring in A. ocellaris, showing similar
but not the same differentiation patterns. Four major genetic lineages with eight distinct
clades were revealed with CR, while the microsatellite dataset discovered three major lineages
and increased lineage mixing. Possibly, these two marker systems resolve different time
ranges. While the mitochondrial DNA still contains traces of historical separation processes
the microsatellites reveal the more recent genetic situation. Both markers show the influences
of geological history and distance between sites, as well as connectivity through the major
surface currents on the population structure of A. ocellaris. The information about
connectivity patterns among populations of the ornamental fish species A. ocellaris along
major surface currents and restrictions of gene flow in remote areas, e.g. east coast of
Sulawesi, can be used for the spacing of marine protected areas in Indonesia that effectively
secure replenishment in exploited areas. In addition, the different genetic lineages should be
managed as separate stocks for the sustainable use and conservation of genetic diversity.
Furthermore, the phylogenetic analysis uncovered cryptic diversity within the genus
Amphiprion that should be considered when assessing diversity of the region and the
classification of conservation units.
Altogether, the differentiation patterns found in the two species complexes and within the
species A. ocellaris indicate favourable conditions for diversification within the Indo-Malay
Archipelago through the location, dynamic geological history and complexity of the area.
This would support the “centre of origin theory”, although the influence of other processes
might as well increase the biodiversity of the region.

Quite interesting. Not all percula are the same. Solomon and New Britain percula form their own sub-clade.
Unfortunately they didn't sample the black Darwin "ocellaris".


Connectivity and the development of population genetic structure in Indo-West Pacific coral reef communities (Full PDF)

ABSTRACT

Aim To identify connectivity patterns among coral reefs of the Indo-West Pacific.
Projecting connectivity forward in time provides a framework for studying longterm
source–sink dynamics in the region, and makes it possible to evaluate the
manner in which migration shapes population genetic structure at regional scales.
This information is essential for addressing critical gaps in knowledge for conservation
planning efforts in one of the most biologically diverse regions on earth.

Location Coral reefs of the Indo-West Pacific, ranging from 15° S to 30° N and
95° E to 140° E.

Methods Individual-based biophysical dispersal models were used in conjunction
with matrix projection to identify the expected patterns of exchange between
coral reefs over time.

Results Present-day oceanographic conditions lead to the transport of larvae
from the South China Sea into the Coral Triangle region via the Sulu Sea, and from
northern Papua New Guinea and the Solomon Islands via Halmahera. The directionality
of the system leads to the expected accumulation of organisms from
outlying areas into the Coral Triangle region over time, particularly in the vicinity
of the Maluku Islands and eastern Sulawesi. Coral reefs in Papua New Guinea, the
Sulu Archipelago and areas within the Philippines are expected to be areas of high
diversity as well.

Main conclusions Biophysical dispersal models, used in conjunction with
matrix projection, provide an effective means of simulating connectivity structure
across the Indo-West Pacific and thereby evaluating the directionality of genetic
diversity. Migration appears to have a significant influence on population genetic
structure in the region. Based on present-day ocean currents, coral reefs in the
South China Sea, northern Papua New Guinea and the Solomon Islands are contributing
to high levels of diversity in the Coral Triangle.

Keywords
Biodiversity, biogeography, connectivity, coral reefs, Coral Triangle,
individual-based modelling, Indo-West Pacific, population genetic structure.

Not anemonefish specific, but relevant to them nonetheless. A. percula is mentioned.

 

[ThRoewer]

Characterization and cross-amplification of microsatellite markers in four species of anemonefish (Pomacentridae, Amphiprion spp.) (Full PDF)

Abstract
Anemonefish are iconic symbols of coral reefs and
have become model systems for research on larval dispersal
and population connectivity in coral reef fishes. Here we present
24 novel microsatellite markers across four species of
anemonefish and also test 35 previously published markers
for cross-amplification on two anemonefish species in order
to facilitate further research on their population genetics and
phylogenetics. Novel loci were isolated from sequences derived
from microsatellite-enriched or 454 GS-FLX shotgun
sequence libraries developed using congeneric DNA. Primer
testing successfully identified 15 new microsatellite loci for
A. percula, 4 for A. melanopus, 3 for A. akindynos, and 2 for
A. omanensis. These novel microsatellite loci were polymorphic
with a mean of 10±1.6 SE (standard error) alleles per
locus and an average observed heterozygosity of 0.647±0.032
SE. Reliable cross-amplification of 12 and 26 of the 35 previously
published Amphiprion markers was achieved for
A. melanopus and A. akindynos, respectively, suggesting that
the use of markers developed from the DNA of congeners can
provide a quick and cost-effective alternative to the isolation
of new loci. Together, the markers presented here provide an
important resource for ecological, evolutionary, and conservation
genetic research on anemonefishes that will inform
broader conservation and management actions for coral reef
fishes.

Keywords Amphiprion . Clownfish . Coral reefs .
Microsatellite . Population genetics

 

[ThRoewer]

Not clownfish or anemone but somewhat related to anemones:

Sexual System, Sex Ratio, and Group Living in the Shrimp Thor amboinensis (De Man): Relevance to Resource-Monopolization and Sex-Allocation Theories (Full article)

Abstract

The sexual system of the symbiotic shrimp Thor amboinensis is described, along with observations on sex ratio and host-use pattern of different populations. We used a comprehensive approach to elucidate the previously unknown sexual system of this shrimp. Dissections, scanning electron microscopy, size-frequency distribution analysis, and laboratory observations demonstrated that T. amboinensis is a protandric hermaphrodite: shrimp first mature as males and change into females later in life. Thor amboinensis inhabited the large and structurally heterogeneous sea anemone Stichodactyla helianthus in large groups (up to 11 individuals) more frequently than expected by chance alone. Groups exhibited no particularly complex social structure and showed male-biased sex ratios more frequently than expected by chance alone. The adult sex ratio was male-biased in the four separate populations studied, one of them being thousands of kilometers apart from the others. This study supports predictions central to theories of resource monopolization and sex allocation. Dissections demonstrated that unusually large males were parasitized by an undescribed species of isopod (family Entoniscidae). Infestation rates were similarly low in both sexes (≈11%"“12%). The available information suggests that T. amboinensis uses pure search promiscuity as a mating system. This hypothesis needs to be formally tested with mating behavior observations and field measurements on the movement pattern of both sexes of the species. Further detailed studies on the lifestyle and sexual system of all the species within this genus and the development of a molecular phylogeny are necessary to elucidate the evolutionary history of gender expression in the genus Thor.

 

[mcfa2403]

Oops posted this article in a separate thread but probably would've been better placed here

http://link.springer.com/article/10.1007/BF00350870

 

[ThRoewer]

Oops posted this article in a separate thread but probably would've been better placed here

http://link.springer.com/article/10.1007/BF00350870

Thanks for posting it here. It would be nice if more would participate to make this more comprehensive.

I've reformatted it a bit and added the abstract so people can get an idea what it's about without opening the link:

Host selection, location, and association behaviors of anemonefishes in field settlement experiments (Full article)

Abstract

Nine anemonefish species were reared in the laboratory, and individuals were released in the field (Lizard Island, Australia and Madang, Papua New Guinea) at different distances and orientations away from natural (anemone species the fishes are found with in nature) and unnatural species of host anemones. Experiments were conducted to examine factors that could affect the settlement behaviors of the fishes: current velocity, distance and orientation of the fishes to the anemones, chemical vs visual cues, and presence of conspecific or heterospecific fishes. The fishes were usually attracted toward natural host species of anemones but not towards unnatural host anemone species nor to pieces of dead coral. Host selection during settlement provided the best explanation for the host specificity patterns displayed by anemonefishes in nature. The fishes used chemical cues released from the anemones to identify and locate the appropriate host species and could effectively locate the anemones from a maximum distance of 8 m downstream. Fishes released upstream or to the side of anemones (where anemone chemicals were assumed to be reduced or absent) were much less successful in locating anemones. The ability of the fishes to locate natural host anemones was strongly reduced when there was no water current. The presence of resident anemonefishes on host species of anemones did not influence the attraction behavior of anemonefishes released downstream from the anemones. Once the released fishes got close to or entered the anemones, the resident fishes would generally bite and chase them until the recruits left the anemones. Most fishes were not stung upon initial contact with the anemones.