| Scientific papers |
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| Herler J., Koblmüller S. & Sturmbauer C. (2009): Phylogenetic relationships of coral-associated gobies (Teleostei, Gobiidae) from the Red Sea based on mitochondrial DNA data. Marine Biology, 156: 725-739. |
Abstract |
| Schiemer L., Niedermüller S. & Herler J. (2008): The influence of colony size and coral health on the occupation of associated gobies (Pisces: Gobiidae). Coral Reefs, 28: 137-142. |
Abstract |
| Wall M. & Herler J. (2008): Post-settlement migration patterns and homing in the coral-associated fish Gobiodon histrio (Teleostei: Gobiidae). Behavioral Ecology, 20: 87-95. |
Abstract |
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Michiels N. K., Anthes N., Hart N. S., Herler J., Meixner A. J., Schleifenbaum F., Schulenburg H., Schulte G., Siebeck U. E. & Sprenger D. (2008): Red fluorescence in reef fishes. BMC Ecology, 8:16.
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Abstract |
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Riedlecker E. & Herler J. (2008): Trophic morphology of the coral-associated genus Gobiodon (Teleostei: Gobiidae) from the Red Sea. Journal of Zoological Systematics and Evolutionary Research doi: 10.1111/j.1439-0469.2008.00497.x
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Abstract |
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Postl L., Herler J., Bauer C., Maderbacher M., Makasa L. & Sturmbauer C. (2008): Geometric morphometrics applied to viscerocranial bones in three populations of the Lake Tanganyika cichlid fish Tropheus moorii. Journal of Zoological Systematics and Evolutionary Research, 46: 240-248.
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Abstract |
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Maderbacher M., Bauer C., Herler J., Postl L., Makasa L. & Sturmbauer C. (2008): Assessment of traditional versus geometric morphometrics for discriminating populations of the Tropheus moorii species complex, a Lake Tanganyika model for allopatric speciation. Journal of Zoological Systematics and Evolutionary Research, 46: 153-161.
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Abstract |
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Herler J., Lipej L. & Makovec T. (2007): A simple technique for digital imaging of live and preserved small fish specimens. Cybium 31(1): 39-44.
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Abstract |
| Dirnwöber, M. & Herler, J. (2007): Microhabitat specialization and ecological consequences for coral gobies of the genus Gobiodon in the Gulf of Aqaba, northern Red Sea. Marine Ecology Progress Series 342: 265-275. |
Abstract |
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Herler, J. (2007): Microhabitats and ecomorphology of coral- and coral rock-associated gobiid fish (Teleostei: Gobiidae) in the northern Red Sea. Marine Ecology 28 (Suppl. 1): 82-94.
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Abstract |
| Herler J., Patzner, R. & Hilgers H. (2006): Notes on the egg envelope and number of oocytes in two Gobius species (Teleostei: Gobiidae) from the northern Adriatic. Zeitschrift f. Fischkunde, 8(1/2): 1-7. |
Abstract |
| Herler J., Hilgers H. & Patzner, R. (2006): Osteology and dentition of two Mediterranean Gobius species (Teleostei, Gobiidae). Italian Journal of Zoology, 73(2): 105-115. |
Abstract |
| Herler J. & Hilgers H. (2005): A synopsis of coral and coral-rock associated gobies (Pisces: Gobiidae) from the Gulf of Aqaba, northern Red Sea. aqua, Journal of Ichthyology and Aquatic Biology, 10 (3): 103-132. |
Abstract |
| Herler J. & Patzner R. (2005): Spatial niche and ecology of two Gobius species (Teleostei: Gobiidae) in the northern Adriatic Sea. Marine Ecology, 26: 121-129. |
Abstract |
| Herler Jürgen, Patzner Robert & Sturmbauer Christian (2005): A preliminary revision of the Gobius auratus species complex with redescription of Gobius auratus Risso, 1810. Journal of Natural History 39 (14):1043-1075. |
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| Herler Jürgen & Kovacic Marcelo (2002): Lebetus guilleti (Teleostei: Gobiidae) in the northern Adriatic Sea: first record and details on the species' morphology. Annales 12: 177-188. |
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| Stachowitsch Michael, Kikinger Reinhard, Herler Jürgen, Zolda Pamela & Geutebrück Ernst (2002): Offshore oil platforms and fouling communities in the southern Arabian Gulf (Abu Dhabi). Marine Pollution Bulletin 44 (9): 853-860 |
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Herler Jürgen & Patzner Robert (2002): New records of Didogobius splechtnai Ahnelt & Patzner, 1995 (Pisces: Gobiidae) from the Tyrrhenian and northern Adriatic Sea. Cybium 26: 153-155.
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Herler Jürgen, Ahnelt Harald & Scsepka Sonja (1999): Morphologische Untersuchungen an zwei höhlenbewohnenden Meergrundeln (Pisces: Gobiidae) des westlichen Mittelmeeres. Ann. Naturhist. Mus. Wien 101 B: 489-507.
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Herler Jürgen, Patzner Robert, Ahnelt Harald & Hilgers Helge (1999): Habitat selection and ecology of two speleophilic gobiid fishes (Pisces: Gobiidae) from the western Mediterranean Sea. P.S.Z.N. Marine Ecology 20 (1): 49-62.
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Scsepka Sonja, Ahnelt Harald & Herler Jürgen (1999): Morphology of two rare Mediterranean gobiid fishes (Teleostei: Gobiidae). Cybium 23: 169-187.
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Ahnelt Harald, Herler Jürgen, Scsepka Sonja & Patzner Robert (1998): First records of two rare Mediterranean Gobiidae in the northern Tyrrhenian Sea. Cybium 22 (2): 183-186.
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| Book chapters |
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| Michael Stachowitsch & Herler Jürgen (2004): The coral reefs of Aqaba: Jordan's Pearl at the Red Sea. Denisia 14, Upper-Austrian museum, Linz, Austria: pp. 479-500. |
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| Book reviews |
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| Herler Jürgen (2004): P. Sale: Coral Reef Fish Ecology. 2nd edition. Published in P.S.Z.N. I Marine Ecology. |
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| Congress contributions |
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Herler J., Dirnwöber M., Schiemer L., Niedermüller S. (2008): Host specificity, spatial niche diversity and adaptations of coral-associated gobies in the northern Red Sea. Oral presentation at 11th ICRS (International Coral Reef Symposium), Fort Lauderdale, USA, July 2008.
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Abstract |
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Wall M., Herler J. & Ott J. (2008): Experimental evaluation of post-settlement movement in the coral-associated goby Gobiodon histrio. Poster presentation at at 11th ICRS (International Coral Reef Symposium), Fort Lauderdale, USA, July 2008.
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Abstract |
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Herler J. (2008): Ecology and morphology of coral-associated gobies (Gobiidae) in the Red Sea. Oral presentation at the 6th conference of the German Ichthyological Society, Munich (Germany), March 2008.
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Herler J. (2007): Shaping up - Eco-morphology and growth patterns in coral-associated fishes. Poster presentation at ECI (European Congress of Ichthyology) XII Dubrovnik (Sept. 2007).
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Abstract |
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Riedlecker E., Herler J., Hilgers H.: JAWS (2007): Trophic Morphology of Coral-Associated Fishes From The Red Sea. Poster presentation at ECI (European Congress of Ichthyology) XII Dubrovnik (Sept. 2007).
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Abstract |
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Schiemer L, Niedermüller S., Herler J. (2006): Does live coral cover and coral health influence the population of highly specialized reef fishes?: Poster presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006).
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Abstract |
| Niedermüller S., Schiemer L., Herler J. (2006): Interactions between coral-feeding and coral-inhabiting reef fishes in the Red Sea: Poster presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006). |
Abstract |
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Herler J. (2006): Morphological adaptations to microhabitats in coral-associated fishes: Oral presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006).
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Abstract |
| Dirnwöber Markus & Herler Jürgen (2005): Microhabitat choice of selected Gobiodon species (Pisces: Gobiidae) in the Gulf of Aqaba, northern Red Sea. Poster presentation at 40th European Marine Biological Symposium, Vienna (Aug. 2005). |
Abstract |
| Herler Jürgen (2005): Inaccessible shallow-water habitats: a realm for marine gobiid dwarfs. Oral presentation at the 40th European Marine Biological Symposium, Vienna (Aug. 2005). |
Abstract |
| Herler Jürgen, Stachowitsch Michael, Zolda Pamela & Waitzbauer Wolfgang (2003): Classroom Coral Reef: Practical marine ecology at the University of Vienna. Poster presentation at the 1st Austrian Reef Workshop, Vienna, May 2003. |
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| Herler Jürgen & Patzner Robert (2001): Microhabitats od cryptobenthic gobiid fish in submarine cave systems. Poster presentation at ECI X, Tenth European Congress of Ichthyology, Prague, Sept. 2001. |
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| Herler Jürgen (2001): Ökologie und morphologische Anpassungen kleiner, höhlenbewohnender Meergrundeln. Oral presentation at the 3rd meeting of the Ichthyological Society (GfI), Vienna, Aug. 2001. |
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Herler J., Koblmüller S. & Sturmbauer C. (2009): Phylogenetic relationships of coral-associated gobies (Teleostei, Gobiidae) from the Red Sea based on mitochondrial DNA data. Marine Biology, 156: 725-739.
Abstract:
Bryaninops, Gobiodon, Paragobiodon and Pleurosicya are the most abundant genera of coral-associated gobies. These genera are adapted to live coral, while other small reef gobies (e.g. the genus Eviota) show no obligate association with this living substrate. Thirteen coral-associated species and two Eviota species were sampled from different regions of the Red Sea, along with four populations/species of Gobiodon from the Indian and western Pacific Oceans. A molecular phylogenetic analysis was performed using partial sequences of 12S rRNA, 16S rRNA and cytochrome b (cyt b) mitochondrial genes, 1,199 base pairs in total. Several clades were consistently resolved in neighbour joining-, maximum parsimony-, maximum likelihood and Bayesian analyses. While each of the four genera Gobiodon, Paragobiodon, Bryaninops and Pleurosicya proved to be monophyletic, their relative position in the phylogeny did not support an emergence of coral-associated gobiids as a monophyletic assemblage. Instead, two separate monophyletic sub-groups were discovered, the first comprising Gobiodon and Paragobiodon, and the second Bryaninops and Pleurosicya. Our molecular phylogenetic examinations also revealed one unassigned species of Gobiodon from the Maldives as a distinct species and confirmed three putative and yet unassigned species from the Red Sea. Moreover, the uniformly black colored species of Gobiodon are not monophyletic but have evolved independently within two distinct species groups. Genetic distances were large in particular within Pleurosicya and Eviota. Estimated divergence times suggest that coral-associated gobies have diversified in parallel to their preferred host corals. In particular, divergence times of Gobiodon species closely match those estimated for their typical host coral genus Acropora.
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Schiemer L., Niedermüller S. & Herler J. (2008): The influence of colony size and coral health on the occupation of associated gobies (Pisces: Gobiidae). Coral Reefs, doi: 10.1007/s00338-008-0420-5.
Abstract: Fishes of the genus Gobiodon are habitat specialists by their association with Acropora corals. Little is known about the parameters that define host coral qualityfor these fishes, in particular their breeding pairs. Data were collected in the northern Red Sea using 10 9 1-mbelt transects in different reefs and zones. Gobiid density was highly correlated with coral density over all sites and zones, and the more specialized goby species preferredcoral species that are less vulnerable to environmental stress. Moreover, the occupation rate of corals by gobybreeding pairs significantly increased with colony size and decreased with partial mortality of colonies. Logistic regression showed that both coral size (being most important) and partial mortality are key factors influencing the occupation by breeding pairs. This study provides the first evidence that breeding pairs of coral-associated gobiids have more advanced habitat requirements than conspecifics in other social states. As coral reefs are threatenedworldwide and habitat loss and degradation increase, this information will help predict the potential effects on those reef fishes obligatorily associated with live corals.
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Wall M. & Herler J. (2008): Post-settlement migration patterns and homing in the coral-associated fish Gobiodon histrio (Teleostei: Gobiidae). Behavioral Ecology doi:10.1093/beheco/arn118.
Abstract: Coral-associated gobies are highly specialized reef fishes with high host-coral fidelity. Flexibility in habitat choice, however, isimportant to compensate for potential habitat alteration or loss, but detailed information about the postsettlement movementbehavior of such gobies is lacking. We examined movement patterns in Gobiodon histrio, both under natural conditions and duringsubsequent field experiments, involving breeding pair or partner removal from 3 of the 4 investigation plots. Additionally, we investigated homing behavior, and 2 aquaria experiments were designed to assess home coral and partner recognition of adultfish taken from breeding pairs. Under natural conditions, the movement rate was high for single adults, whereas breeding pairsshowed high home-coral fidelity. Manipulations revealed little change of natural patterns except in single adults, which slightlydecreased their movement rate in the breeding pair removal plot. In the homing experiment, 17% of tested fish returned to theirhome coral even after displacement of 4 m, and homing success was much higher at shorter distances (100% at 0.5 m, 53% at 2.25 m). In the aquarium, G. histrio exhibited higher recognition of its home-coral colony (75%) than of its breeding pair partner (60%). Our study shows that G. histrio frequently moves between corals, although this depends on the social status (juvenile,single adult, breeding pair) of the individuals. The high proportion and movement rate of single adults indicate low sensitivity tohabitat alteration but also limited high-quality habitats in which breeding pairs could be established. Hence, vulnerability tohabitat loss increases when individuals breed.
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Michiels N. K., Anthes N., Hart N. S., Herler J., Meixner A. J., Schleifenbaum F., Schulenburg H., Schulte G., Siebeck U. E., Sprenger D. (2008): Red fluorescence in reef fishes. BMC Ecology, 8:16. doi:10.1186/1472-6785-8-16.
Abstract:
Background: At depths below 10 m, reefs are dominated by blue-green light because seawater selectivelyabsorbs the longer, 'red' wavelengths beyond 600 nm from the downwelling sunlight. Consequently, thevisual pigments of many reef fish are matched to shorter wavelengths, which are transmitted better bywater. Combining the typically poor long-wavelength sensitivity of fish eyes with the presumed lack ofambient red light, red light is currently considered irrelevant for reef fish. However, previous studiesignore the fact that several marine organisms, including deep sea fish, produce their own red luminescenceand are capable of seeing it.
Results: We here report that at least 32 reef fishes from 16 genera and 5 families show pronounced redfluorescence under natural, daytime conditions at depths where downwelling red light is virtually absent.Fluorescence was confirmed by extensive spectrometry in the laboratory. In most cases peak emissionwas around 600 nm and fluorescence was associated with guanine crystals, which thus far were known fortheir light reflecting properties only. Our data indicate that red fluorescence may function in a context ofintraspecific communication. Fluorescence patterns were typically associated with the eyes or the head,varying substantially even between species of the same genus. Moreover red fluorescence was particularlystrong in fins that are involved in intraspecific signalling. Finally, microspectrometry in one fluorescentgoby, Eviota pellucida, showed a long-wave sensitivity that overlapped with its own red fluorescence,indicating that this species is capable of seeing its own fluorescence.
Conclusion: We show that red fluorescence is widespread among marine fishes. Many features indicatethat it is used as a private communication mechanism in small, benthic, pair- or group-living fishes. Manyof these species show quite cryptic colouration in other parts of the visible spectrum. High inter-specificvariation in red fluorescence and its association with structures used in intra-specific signalling furthercorroborate this view. Our findings challenge the notion that red light is of no importance to marine fish, calling for a reassessment of its role in fish visual ecology in subsurface marine environments.
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Riedlecker E. & Herler J. (2008): Trophic morphology of the coral-associated genus Gobiodon (Teleostei: Gobiidae) from the Red Sea. Journal of Zoological Systematics and Evolutionary Research (in press).
Abstract: Trophic morphology plays a major role in niche diversification among the highly diverse fish fauna of coral reefs. It gives insight into feedingtypes and is useful in taxonomy, as it can be used to differentiate between species and to estimate phylogenetic relationships. The gobiid genus Gobiodon comprises obligate coral dwelling species that are widespread on Red Sea and Indo-Pacific reefs. Yet very little is known about theirecology and behaviour of feeding. In this study, viscerocranial and oral jaw morphology was investigated in seven species of Gobiodon that occurin the Red Sea. Osteological analyses were carried out on enzyme cleared and alizarin red stained specimens. Shape variation of theviscerocranium was analyzed using a landmark-based geometric morphometric method on digital scans of hand drawings and visualized in thin-plate splines. Shape was determined by placing landmarks on skeletal elements in their articulated state. Morphology of the dentary andpremaxilla was examined in further detail after disarticulation. A combination of landmarks and semilandmarks was applied to digitalphotographs of the oral jaws. It was shown that orbit size influences viscerocranial morphology by delimiting the lower jaw articulation angle.The premaxilla differs both in its extent and direction of curvature and in the structure of the articular process. Form changes in the dentary aremainly caused by variation of curvature and depth. A significant relationship between oral jaw shape and the number of anterior rows of teethwas found. Morphological diversity of selected elements is used to generate hypotheses concerning the trophic biology and niche diversification of Gobiodon. Brief dietary and in situ behavioural observations were carried out to further develop and test hypotheses.
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Postl L., Herler J., Bauer C., Maderbacher M., Makasa L. & Sturmbauer C. (2008): Geometric morphometrics applied to viscerocranial bones in three populations of the Lake Tanganyika cichlid fish Tropheus moorii. Journal of Zoological Systematics and Evolutionary Research, 46: 240-248.
Abstract: Lake Tanganyika comprises the oldest and most diverse species flock of cichlid fishes. Many species are subdivided into numerous populations,often classified as geographical races, colour morphs or sister species. Unlike younger species flocks, in which speciation is accompanied by ecomorphologicaldiversification that of Lake Tanganyika is at a mature stage with little further morphological change, most probably caused bystabilizing selection. This study addresses body shape differences among three genetically distinct but morphologically similar populations ofTropheus moorii, by focusing on bony structures of the cichlid head. We test by means of geometric morphological methods whether shapechanges in the cichlid head are based on particular osteological differences. Specimens were disarticulated enzymatically, and standardized digitalimages of the disarticulated bony elements were taken. A landmark system was established for the dentary, articular, premaxilla, quadrate and thepreopercle. Only the dentary shows significant differentiation among the three populations. Since all three populations live in similar cobblehabitats and occupy the same trophic niche, the observed difference in the shape of the dentary can either be explained by different directionalselection due to subtle habitat differences, or by neutral drift constrained by borders enforced through stabilizing selection. Lack of differencemight indicate stabilizing selection on bone shape.
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Maderbacher M., Bauer C., Herler J., Postl L., Makasa L. & Sturmbauer C. (2008): Assessment of traditional versus geometric morphometrics for discriminating populations of the Tropheus moorii species complex, a Lake Tanganyika model for allopatric speciation. Journal of Zoological Systematics and Evolutionary Research, 46: 153-161.
Abstract: Lake Tanganyika harbours the oldest and ecologically, morphologically and behaviourally most diverse species flock of cichlid fishes. Its speciesare excellent subjects for the study of explosive speciation and adaptive radiation. Many species are subdivided into numerous genetically andphenotypically distinct populations, often classified as distinct geographical races or colour morphs, which mostly differ in colour and much lessin terms of morphology. This study for the first time quantifies morphological differences among such morphs by studying three populations ofTropheus moorii. We compared 'traditional morphometrics' (TM) and 'geometric morphometrics' (GM) to explore their potential fordiscriminating populations. So far species description and population discrimination are almost solely based on TM in the form of standardizedmeasurements, although specialists are aware of their lack of diagnostic power for discrimination of closely related entities. Moreover,comprehensive TM measurements are time consuming and can best be done on dead specimens which have to be preserved in the casere-measuring is necessary. In contrast, GM can also be based on photographs and computer scans of anaesthetized fish, so that the sameindividual can be repeatedly analysed during its ontogeny. Here, we show that GM is more flexible in data acquisition and more powerful in thediscrimination of species and closely related populations. While TM is restricted to distances and ratios of distances, GM not only includes thesemeasurements indirectly, but also allows for body shape analysis using a semi-landmark approach. It can be equally standardized as TM bydefining diagnostic landmarks. Data description by canonical variate analysis was most informative using GM data including semi-landmarks, whereas differences between populations were significant (p < 0.05) based on both morphological approaches.
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Herler J., Lipej L. & Makovec T. (2007): A simple technique for digital imaging of live and preserved small fish specimens. Cybium 31(1): 39-44.
Abstract: The present methodological paper presents a simple technique for digital imaging of small fish specimens using conventional flatbed scanners. Preparing such scanners with a plasticine pool enables fish specimens to be scanned under submerged conditions in water, ethanol or glycerine, depending on whether they are alive or preserved. This technique relies on a quickly prepared, less complicated setup than in photography and provides the opportunity to gain digital images of small fish in the laboratory as well as – with some restrictions – in the field. Lateral scans can be easily made of live specimens after narcotisation or of preserved fish. The scanning method yielded high-quality images of near- l i v e colours of live fish and of preserved coloration. Images had good contrast, sharpness and illumination, minimal or no shadows and high resolutions when scanned on high-quality scanners. Depth of field in images was good for fishes of less than 20 cm length and less than 2 cm body width. The method is recommended for applications where digital images are required for body shape analyses, such as geometric morphometric approaches, for qualitative or quantitativ analyses of coloration patterns, for fish (re-)identification, and as a basis for illustrations or for publication in electronic sources or print media.
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Dirnwöber, M. & Herler, J. (2007): Microhabitat specialization and ecological consequences for coral gobies of the genus Gobiodon in the Gulf of Aqaba, northern Red Sea. Marine Ecology Progress Series, 342: 265-275.
Abstract: The microhabitat selection and distribution of six coral-associated species of Gobiodon was examined in the Gulf of Aqaba, northern Red Sea, including three recently discovered species. A total of 1626 fishes were counted visually using 10 x 1 m belt transects in 1731 colonies of 13 species of Acropora. Niche segregation was observed at the level of coral species. Gobiodon sp. 2 was the most specialized, occupying only A. hyacinthus; G. sp. 1 was most generalized (three species of Acropora). G. reticulatus was a zone specialist that preferred deeper water regions. Less specialized species were able to use substitute host corals, which enabled them to maintain extraordinarily high abundance. G. histrio, for example, preferred the rare A. digitifera but was common in the very abundant A. acuminata, although proportionally fewer breeding pairs were established in the latter. When compared to the western Pacific, G. histrio showed a more generalized behaviour in the northern Red Sea, and different coral species served as host corals; the latter also holds true for the even more generalized G. rivulatus. Hence, species of Gobiodon appear to alter host-use and degree of specialization on a global scale.
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Herler, J. (2007): Microhabitats and ecomorphology of coral- and coral rock-associated gobiid fish (Teleostei: Gobiidae) in the northern Red Sea. Marine Ecology 28 (Suppl. 1): 82-94.
Abstract: Twenty-one coral- and coral-rock associated gobiid fish species were examined in the Gulf of Aqaba, northern Red Sea in autumn 2003 and spring 2004. They represent the seven genera Bryaninops, Eviota, Gobiodon, Paragobiodon, Pleurosicya, Priolepis and Trimma. Clear spatial niche segregation was found in all species. Branching corals of the genus Acropora were obligatorily inhabited by Gobiodon spp., while Paragobiodon echinocephalus was restricted to Stylophora pistillata. Three Bryaninops species showed species-specific associations with Acropora spp., Millepora dichotoma and Cirripathes sp.. Most of the five Eviota species had weak associations with live corals but frequented coral rock. Among the genus Pleurosicya, two species were encountered. Pleurosicya micheli frequented massive scleractinian corals, while P. prognatha occupied various species of Acropora. Priolepis semidoliata was only occasionally observed and found on coral rock. Weak associations with scleractinians corals were documented in Trimma avidori, and T. mendelssohni, both of which inhabit coral rock. Principal component and cluster analyses showed several morphological features to be important ecomorphological traits. Gobiid species inhabiting encrusting or massive corals have a more depressed body than species in branching corals. Eye size was well correlated with preferred water depth, especially in the coral-associated species. A typical gobiid feature – the pelvic disc – was found in very different character states and corresponded with preferred microhabitats. A well-developed suctorial pelvic disc was typical for obligate coral-dwellers.
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Herler J., Patzner, R. & Hilgers H. (2006): Notes on the egg envelope and number of oocytes in two Gobius species (Teleostei: Gobiidae) from the northern Adriatic. Zeitschrift f. Fischkunde, 8(1/2): 1-7..
Abstract: The surface structure of the egg envelope and the amount of oocytes in the two closely related gobiids Gobius fallax and Gobius auratus were investigated by scanning electron and light microscopy. Mature oocytes of both species exhibit a filament adhesion apparatus surrounding the micropyle at the animal pole, consisting of a perforated plate and numerous filaments originating from its rim. Both species show more than 100 large perforations in the plate and 160 to 250 adhesive filaments. Batch fecundity in females was high for both species, with up to 6,000 mature oocytes counted from G. fallax and a maximum of 5,000 in G. auratus.
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Herler J., Hilgers H. & Patzner, R. (2006): Osteology and dentition of two Mediterranean Gobius species (Teleostei, Gobiidae). Italian Journal of Zoology, 73(2): 105-115.
Abstract: Osteological examinations of the two gobiid species Gobius fallax and the recently described colour morph of G. auratus from the northern Adriatic Sea revealed interspecific conformity in most features. These closely related species only show slight trends of osteological differentiation; clear discriminating features were hardly determined also due to high intraspecific variations. Both the metapterygoid bridge to the quadrate and the tail skeleton exhibit a somewhat stronger development in G. fallax. Although the counts of teeth in jaws and pharynx show differences, the high intraspecific variation in G. fallax did not enable discrimination between the two species. G. fallax and G. auratus exhibit skeletal features, which are common and rather primitive among the Gobiinae such as a pterygiophore formula of 3-22110, a metapterygoid bridge to the quadrate that is variable in its extension, a well-developed connection between preopercle and symplectic, and a scapula with only the dorsal part of the foramen ossified.
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Herler J. & Hilgers H. (2005): A synopsis of coral and coral-rock associated gobies (Pisces: Gobiidae) from the Gulf of Aqaba, northern Red Sea. aqua, Journal of Ichthyology and Aquatic Biology, 10 (3): 103-132.
Abstract: Field investigations in the
Gulf of Aqaba
,
northern
Red Sea
(Dahab,
Sinai
,
Egypt
) revealed 21 species in seven genera of gobiid fish associated with corals and/or coral rock. Three as yet undetermined species of Gobiodon (G. sp.1, 2 and 3) were found to be new for the
Red Sea
. Like the congeneric G. citrinus, G. histrio, G. reticulatus and G. rivulatus, they are obligate dwellers of Acropora corals. Among the other genera, Bryaninops yongei significantly differs from its congener B. ridens in live coloration as well as by its preference for Cirripathes sp., while the latter obligatorily inhabits Millepora dichotoma. A third species, B. natans, exhibits hyperbenthic behaviour, violet eyes and a yellow belly on the otherwise transparent body and is commonly associated with Acropora loripes and A. squarrosa. The five Eviota species examined were less specialized and associated with live corals of various growth forms and/or with coral rock. Paragobiodon echinocephalus showed very low occupation rates of the highly abundant Stylophora pistillata and was mostly found in small breeding pairs. Within the genus Pleurosicya, P. micheli is more slender than P. prognatha and shows a distinct longitudinal red internal stripe, while the latter is transparent with a few brown speckles in life. Pleurosicya micheli inhabits massive scleractinians, whereas P. prognatha is found in Acropora. Priolepis semidoliata was rare and associated with coral rock. Weak associations with scleractinians were also found in Trimma avidori, which was common but prefers steep or overhanging substrates mostly consisting of coral rock. Trimma mendelssohni prefers coral rock caves.
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Herler J. & Patzner R. (2005): Spatial niche and ecology of two Gobius species (Teleostei: Gobiidae) in the northern Adriatic Sea. Marine Ecology, 26: 121-129.
Abstract: The habitat characteristics and spatial segregation of the two common gobies Gobius fallax Sarato, 1889 and Gobius auratus Risso, 1810 were investigated by fish frequency and abundance estimates through visual counts in the northern Adriatic Sea. The latter species is represented by a recently described, unusual colour morph in the northern Adriatic Sea. G. fallax was observed at five of the nine locations examined and its abundance did not differ between two of three transect locations at Piran (Slovenia) and at the western coast of Cres (Kvarner region, Croatia). G. auratus was not found in the Gulf of Trieste but was present at several Kvarner locations, and co-occurred with G. fallax at one location at Cres. Both inhabit rocky substrates but they show different preferences for substrate inclinations and bathymetric segregation. G. fallax was most frequent between 2 and 8 m depth and was most abundant on substrate inclining less than 30°. Its highest abundance over entire transects was 0.3 individuals.m-2 but within certain transect sections this increased to 1.25 individuals.m-2. G. auratus attained its highest abundance in depths below 8 m and at substrate inclinations between 30 and 90°. This species attained its highest values at the western coast of Cres, where it reached a maximum of 1.5 indiv.m-2 over entire transects but even up to 3 indiv.m-2 in certain transect sections. At Krk, the maximum abundance over entire transects was only 0.3 indiv.m-2.
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Herler Jürgen, Patzner Robert & Sturmbauer Christian (2005): A preliminary revision of the Gobius auratus species complex with redescription of Gobius auratus Risso, 1810. Journal of Natural History, 39 (14): 1043-1075.
Abstract: The study focused on two gobiid taxa from the northern Adriatic Sea. External features and coloration suggest identification of one of these with Gobius auratus Risso, 1810. This species is characterised by a deeply emarginated pelvic disc and meristic features of typically second dorsal fin rays I/14, anal rays I/13 and scales in lateral series 45. The live coloration of the northern Adriatic population shows a yellow basic coloration but with distinct longitudinal lines of red dots and therefore, its colour significantly differs from the uniformly yellow coloration supposed to be typical for this species. A redescription of this putative G. auratus Risso, 1810 is carried out to extend the morphological characteristics of the species to cover also the northern Adriatic population. Two colour morphs are described and morphometrics as well as details on the lateral line system of the species are newly included in the species description. The second Adriatic taxon was assigned to G. fallax Sarato, 1889. Both taxa from the northern Adriatic were compared to G. xanthocephalus Heymer and Zander, 1992 from the western Mediterranean and Atlantic indicating their clear distinction. The northern Adriatic specimens of G. auratus show some similarities with the western Mediterranean and Atlantic G. xanthocephalus concerning life coloration, but differ in a series of features such as certain morphometrics (head and pelvic disc longer in the former, fifth pelvic ray, relative to fourth, longer in the latter), meristics (second dorsal rays mostly I/14 in the former and I/15 in the latter, anal rays mostly I/13 vs. I/14, scales in lateral series about 45 vs. 48). Gobius fallax is distinguishable by a different coloration pattern and shows the lowest values in mean fin and scale meristics. Phylogenetic analysis of DNA sequences of the first section of the control region revealed that all individuals of both colour morphs of G. auratus and of G. fallax form a single cluster of closely related haplotypes which are not sorted according to the species, suggesting their recent origin. Only G. xanthocephalus is, in agreement to morphology, also genetically distinct and represents a separate clade. The existence of a Gobius auratus species complex is therefore confirmed.
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Herler Jürgen & Kovacic Marcelo (2002): Lebetus guilleti (Teleostei: Gobiidae) in the northern Adriatic Sea: first record and details on the species' morphology. Annales 12: 177-188.
Abstract: The occurrence of Lebetus guilleti (Le Danois, 1913) is described for the first time from the northern Adriatic Sea, Croatian coast. Eight females (SL 12.1 – 17.4 mm) and five males (SL 10.6 – 12.5 mm) were collected in the Kvarner region, south of Rijeka on sandy substrates in depths between 6 and 13 m in 1999 and 2001. A second small population was documented photographically at the western coast of Istria, near Rovinj in May 2002. The collected specimens were assigned to L. guilleti (Le Danois, 1913) by the following features: small body size, specific body coloration, complete loss of the head lateral line canals, presence of suborbital row a, limited number of head sensory papillae with two interorbital rows, elongate dorsal fin rays and meristic values of D2 I/7-8, A I/4-5, P 14-15, LL 24-26 and VC 25-26. This recent finding enables a more detailed description of the morphology of this little known species as given below. Morphometrics, meristic values, lateral line system, coloration and skeletal features as well as ecology are described and compared with related gobiid genera.
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Stachowitsch Michael, Kikinger Reinhard, Herler Jürgen, Zolda Pamela & Geutebrück Ernst (2002): Offshore oil platforms and fouling communities in the southern Arabian Gulf (Abu Dhabi). Marine Pollution Bulletin 44 (9): 853-860.
Abstract: This study examined the fouling organisms on the legs of offshore oil platforms at two sites in southern Arabian Gulf (offshore Abu Dhabi, United Arab Emirates). 100% of the metal structures was colonized by encrusting organisms. Both the number of individuals and the total biomass tended to decrease with depth. The total weight of non-living, biogenic material (e.g., dead shells) always exceeded that of living organisms. Sessile filter feeders dominated the biomass, whereas small mobile forms had the largest number of individuals. The biomass at the deeper platform (22m) was dominated by bivalves, barnacles and bryozoans, while polychaetes and amphipods had the greatest number of individuals. Biomass values here ranged from 1g/0.1m² at 20m to 147g/0.1m² at 5m; the corresponding individual numbers were 266 (20m) and 11,814 indiv./0.1m² (5m). The results at the shallower platform (11m) differed in several respects: sponges replaced bryozoans (biomass), whereas brittle stars additionally became important (individuals). Biomass values here ranged from 84g/0.1m² at 10m to 153g/0.1m² at 0m; the corresponding individual numbers were 692 (10m) and 3,125 indiv./0.1m² (0m). The composition of the fouling community differs from that of the surrounding bottom, and the potential role of this community and of the structures themselves in the Gulf is discussed.
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Herler Jürgen & Patzner Robert (2002): New records of Didogobius splechtnai Ahnelt & Patzner, 1995 (Pisces: Gobiidae) from the Tyrrhenian and northern Adriatic Sea. Cybium 26: 153-155.
Abstract: The recently described species Didogobius splechtnai Ahnelt & Patzner, 1995 was for the first time discovered at the western Mediterranean Island of Ibiza (Baleares/Spain). There it was found to be a very cryptic species which exclusively inhabits fine sediment bottoms of the innermost areas of submarine caves. Four years later, this species was also detected in the central Mediterranean Sea at the Island of Lampedusa, south-west of Sicily. Now it has also been found at the Islands of Elba and Sardegna/Tyrrhenian Sea as well as in the northern Adriatic Sea near Pula/Croatia. From each area one specimen was collected for identification and morphological descriptions.
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Herler Jürgen, Ahnelt Harald & Scsepka Sonja (1999): Morphologische Untersuchungen an zwei höhlenbewohnenden Meergrundeln (Pisces: Gobiidae) des westlichen Mittelmeeres.
Ann. Naturhist. Mus. Wien 101 B: 489-507.
Abstract: The morphological characters of two sympatric, cave-dwelling gobiid fishes from the Balearic Island of Ibiza (western Mediterranean Sea), Corcyrogobius liechtensteini (KOLOMBATOVIC, 1891) and Didogobius splechtnai AHNELT & PATZNER, 1995, are described. In addition to body proportions and meristic counts, the lateral line system of both species is presented and osteological features of C. liechtensteini are given. Furthermore, the ontogenetic development of the lateral line head canals is described for both species.
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Herler Jürgen, Patzner Robert, Ahnelt Harald & Hilgers Helge (1999): Habitat selection and ecology of two speleophilic gobiid fishes (Pisces: Gobiidae) from the western Mediterranean Sea. P.S.Z.N. I Marine Ecology 20 (1): 49-62.
Abstract: The life habits and microhabitat selection of speleophilic gobiid fishes were investigated on the Balearic Island of Ibiza (western Mediterranean Sea). Corcyrogobius liechtensteini (KOLOMBATOVIC, 1891) was the most frequent species within submarine crevices, cavities and caves. Didogobius splechtnai AHNELT & PATZNER, 1995 co-occured with C. liechtensteini in several cases but showed a clear spatial separation based on a different microhabitat preference. The microhabitat selection of both species was confirmed by habitat choice experiments in an aquarium. C. liechtensteini was frequent in depths between 5 m and 25 m and attained abundances of 14.2 indiv./m2. This species inhabited the ceilings and upper parts of the walls within the caves. Most specimens of D. splechtnai were found between 7 m and 11 m and showed abundances of approximately 2 indiv./m2. This species occupied the fine sediment bottoms in the innermost parts of crevices and caves. The growth and the maximum age of both species were determined by length-frequency distributions. The overall sex ratio from catches of three different years are given for C. liechtensteini.
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Scsepka Sonja, Ahnelt Harald & Herler Jürgen (1999): Morphology of two rare Mediterranean gobiid fishes (Teleostei: Gobiidae). Cybium 23: 169-187.
Abstract: The Mediterranean gobiids Didogobius splechtnai and Gammogobius steinitzi occur sympatrically in submerged caves at the Balearic Island of Ibiza (Western Mediterranean). Both species inhabit the dark backgrounds of large caves, G. steinitzi mainly the walls and D. splechtnai the sediment-covered bottoms. Morphological characters like body proportions, meristics, the lateral-line system and osteological features are described and compared.
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Michael Stachowitsch & Herler Jürgen (2004): The coral reefs of Aqaba: Jordan's Pearl at the Red Sea. Denisia 14, Upper-Austrian museum, Linz, Austria: pp. 479-500.
Abstract: The coral reefs along Jordan's coast in the Gulf of Aqaba are a unique biological treasure. Building on a long tradi-tion of Austrian researchers in the Red Sea (for example the famed Austro-Hungarian Deep Sea Expeditions of 1896-1898), the University of Vienna's Institute of Ecology and Conservation Biology has for almost a decade been conducting coral reef courses in Aqaba. Beyond introducing new generations of students to the coral reef ecosystem, our work - conducted in small teams concentrating on selected topics - has generated a wealth of data and experience. This is reflected in a series of annual reports, graduate theses, and scientific publications. The demands placed on Jordan's short stretch of coastline are enormous. In the future, Jordan's decision-makers must rely on the advice of professional marine scientists if they wish to achieve a successful balance between commercial interests and fun-damental ecological necessities.
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Herler J., Dirnwöber M., Schiemer L., Niedermüller S. (2008): Host specificity, spatial niche diversity and adaptations of coral-associated gobies in the northern Red Sea. Oral presentation at 11th ICRS (International Coral Reef Symposium), Fort Lauderdale, USA, July 2008.
There are numerous specialized fishes that exploit a variety of spatially restricted habitats incoral reefs, for example gobiids which live in association with live corals or coral rock. In theGulf of Aqaba (northern Red Sea), 21 species belonging to seven genera of tiny reef-associatedgobies were found, occupying a great range of spatial niches. Four genera (Gobiodon,Paragobiodon, Bryaninops and Pleurosicya) are coral-associated among whichGobiodon is the most prominent one. Coral growth forms constrain fish morphology and driveadaptations. Differences in body shape and growth patterns were investigated in Gobiodon bygeometric morphometrics and related to interbranch width of preferred Acropora corals.Restricted interbranch width provide fitness advantages for species that grow more compress,because they attain larger body size in the same corals by being thinner. The swimmingperformance, as tested in aquarium experiments by simulating different coral interbranchspaces, was better in Gobiodon histrio than in G. rivulatus, two species which differ inshape but overlap in habitat use and compete for host corals. Different shapes may even bereflected in internal characters, such as the head skeleton. Specific microhabitat characteristicsmay thus have driven adaptive radiation among these habitat specialists. Niche width (degree ofspecialization) and different competitive abilities among species result in differentialconsequences for species if coral colonies or entire communities become degraded. This wasshown by effects on the frequency of goby breeding pairs found in reefs of very differentconditions, where heavily damaged corals were up to 80% less frequently occupied. As postsettlementmovement experiments have revealed, breeding pairs build stable relationships andprefer certain coral colonies and are thus extremely sensitive to coral degradation and habitatloss.
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Wall M., Herler J. & Ott J. (2008): Experimental evaluation of post-settlement movement in the coral-associated goby Gobiodon histrio. Poster presentation at at 11th ICRS (International Coral Reef Symposium), Fort Lauderdale, USA, July 2008.
Crypto-benthic reef fish play an important role in the functions of coral reef ecosystems.Worldwide degradation of reef puts habitat specialized fishes at high risk by habitat loss. Toreceive a better understanding of the susceptibility of coral-associated fishes to habitat loss,post-settlement movement was surveyed in Gobiodon histrio. After observing movementpatterns under natural conditions in the northern Red Sea, a combination of manipulative fieldand laboratory experiments were conducted. In the field, the homing ability was tested bydisplacing individuals in different distances from their home coral. A considerable differencewas observed between minimum and maximum displacement (0.5m = 100%; 4 m = 16.4% offishes returned). Aquarium experiments were designed to test for the assumption that Gobiodonhistrio can distinguish its host-coral from a choice of different colonies. In addition, a partnerfinding experiment was performed. In both experiments a high fidelity for host corals (75%)and partners (60%) was observed. The study indicates a high movement rate for single adults.In contrast, breeding pairs show a high stability in their habitat choice. Social structure of G.histrio in the northern Red Sea shows similarities to the Western Indo-Pacific but differs in theproportion of single adults, which is much lower in the latter. The high proportion of singleadults and their high movement rate indicates a limitation of high quality habitats (particularAcropora species) for breeding. The apparently more generalized behaviour results fromoccupation of sub-optimal corals by single adults while moving and searching for breedingcorals and partners. This study shows that G. histrio frequently moves between corals but thisdepends on the social status of fishes. Vulnerability of populations to habitat loss increaseshighly when particular corals are affected by damage.
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Herler J. (2008): Ecology and morphology of coral-associated gobies (Gobiidae) in the Red Sea. Oral presentation at the 6th conference of the German Ichthyological Society, Munich (Germany), March 2008.
22 species of coral-rock and coral-associated gobies (Gobiidae) were examined in the Gulf of Aqaba (Sinai), in the northern (Egpyt) and southern Red Sea (Eritrea). Among the latter there are 14 species out of 4 genera (Bryaninops, Gobiodon, Pleurosicya und Paragobiodon) which live in obligatory association with live corals. Hosts for these fishes are anthipatharian (Cirripathes), hydrozoan (Millepora) and scleractinian corals. Several biological and morphological features can be recognized as special adaptations to this particular life-style. These include their sexual and social systems, reductions of squamation and mucous skins, the form of the pelvic fin, different eye indices and especially the body shape, which is a good predictor for host specificity. Thus, there are convergences in the body shape of some genera as a consequence of adaptation to similar microhabitats and ecological constraints play a more important role then phylogenetic ones. Very specific adaptations to branching corals of the genus Acropora are found in the gobiid genus Gobiodon. As assumed from field observations and aquarium experiments, some species within that genus gain fitness advantages through different growth patterns that allow superior competitor status in certain corals.
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Herler J. (2007): Shaping up - Eco-morphology and growth patterns in coral-associated fishes. Poster presentation at ECI (European Congress of Ichthyology) XII Dubrovnik (Sept. 2007).
Abstract: There are numerous specialized fishes that exploit a variety of spatially restricted habitats in coral reefs, for example gobiids which live in association with live corals or coral rock. In the Gulf of Aqaba (northern Red Sea), 21 species belonging to seven genera of tiny reef-associated gobies were found. Some of these genera are among the most habitat-specialized fishes in coral reefs and show various adaptations. In particular, body shape appears to fit the preferred microhabitats. Species of the genus Gobiodon for example inhabit narrowly branched Acropora corals and exhibit very compressed bodies. Variation of overall body shape within this genus (seven species) was investigated by geometric morphometrics based on 2D-landmark data (from digital lateral view scans). Considerable morphological variation was found in relative warps (principal components) analyses of landmark coordinates. Shape variables were correlated with selected traditional morphometrics, also taken from the cross section (3rd dimension) of the fish and, in some cases, with coral interbranch space. Based on the assumption that coral interbranch space delimits fish body width, consequences on growth and maximum fish size were assumed. To test for this, two species - Gobiodon histrio and G. rivulatus-, which have different body shapes, but overlap in their habitat use and compete for host corals in nature, were compared concerning their growth patterns. Additionally, aquarium experiments were carried out to see whether their locomotory performance is influenced by coral interbranch space. Since body size plays a major role in the competitive hierarchy among these reef fishes, larger species are superior competitors and are able to out-compete sister species. A comparison of allometric growth in G. histrio and G. rivulatus reveals that G. histrio attains larger body size by growing deeper but more compressed. Such growth patterns may thus positively influence the competitive ability of a species.
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Riedlecker E., Herler J., Hilgers H. (2007): JAWS: Trophic Morphology of Coral-Associated Fishes From The Red Sea. Poster presentation at ECI (European Congress of Ichthyology) XII Dubrovnik (Sept. 2007).
Abstract: Trophic morphology plays a major role in niche diversification among the highly diverse fish fauna of coral reefs. It gives insight into feeding types and is useful in taxonomy, as it can be used to differentiate between species and to estimate phylogenetic relationships. The gobiid genus Gobiodon comprises obligate coral dwelling species which are widespread on Red Sea and Indo-Pacific reefs. Yet very little is known about their ecology and behavior, especially with regard to their feeding habits. In this study, viscerocranial and oral jaw morphology was investigated in seven species of Gobiodon which occur in the Red Sea. Osteological analyses were carried out on enzyme cleared and alizarin red stained specimens. Shape variation of the viscerocranium was analyzed using a landmark-based geometric morphometric method on digital scans of drawings and visualized in thin-plate splines. Viscerocranial shape was determined by placing landmarks on skeletal elements in their articulated state. Morphology of the dentary and premaxilla was examined in further detail after disarticulation. A combination of landmarks and semi-landmarks was applied to digital photographs of the oral jaws. We find that interspecific shape differences in the viscerocranial bone complex do not necessarily reflect those found in individual elements (e.g. dentary, premaxilla). Orbit size influences viscerocranial morphology by delimiting the lower jaw articulation angle. The premaxilla differs both in its degree and direction of recurvature and in the structure of the externally concave articular process. Form changes in the dentary are mainly caused by variation of curvature and depth. Morphological diversity of selected elements is used to generate hypotheses concerning the trophic biology and niche diversification of Gobiodon and the possible importance of these structures in non-feeding activities.
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Schiemer L, Niedermüller S., Herler J. (2006): Does live coral cover and coral health influence the population of highly specialized reef fishes?: Poster presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006).
Fishes of the genus Gobiodon are strictly associated with living scleractinian (Acropora) corals. AllGobiodon species use a range of species but prefer a single or a few (=host) corals. The presentstudy in the Gulf of Aqaba (northern Red Sea) examined the effect of coral health and live coralcover on these specialists. Six sites (chosen in terms of different exposition, water depth andsupposed live coral cover) were compared. Size, identity and condition of corals and the occupationby six species of Gobiodon were assessed in three 10x1 m belt transects, laid on both the reef crestand reef slope at each site. Live Acropora coral cover ranged from 2.3% to 16.5% between sitesand partial coral mortality varied between 6 ± 2 % (Acropora loripes) to 50 ± 7 % (Acroporavariolosa). Fish density was highly correlated with coral density and live coral coverage over allsites and occupation rates were highly correlated with host coral size. If a certain colony live arearemained, partial mortality did not determine the presence of breeding pairs, which prefer largecolonies. Therefore, not only coral abundance but also the state of coral assemblages influences thecommunity structure of coral-dwelling gobies.
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Niedermüller S., Schiemer L., Herler J. (2006): Interactions between coral-feeding and coral-inhabiting reef fishes in the Red Sea: Poster presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006).
The Chaetodontidae (butterflyfishes) are known to comprise highly specialized coral-feedingspecies. In the northern Red Sea, Chaetodon austriacus - an obligate corallivor - feeds mainly onAcropora corals. These branching scleractinians are a frequently used microhabitat of specializedgobiid fishes (genus Gobiodon) which are assumed to act as a coral predator deterrent. This studyexamines the food selection of Chaetodon austriacus in respect to occupation of corals by gobies at4 different sites in Dahab, South Sinai, Egypt. Bite rates and coral species were noted in six-minuteintervals and corals were subsequently examined for Gobiodon occupation. Bite rates per colonywere not affected by goby occupation, but the number of selected unoccupied corals wassignificantly higher than that of occupied colonies. At all sites, the spectrum of selected coralsdiffered significantly from available corals. Generally, less occupied coral species such asAcropora selago and A. hyacinthus were favored. Species with high occupation rates were eitherlargely avoided (A. loripes) or unoccupied colonies were mainly selected (A. gemmifera). Sincebutterflyfishes also fed on occupied colonies, Gobiodon spp. should not be regarded as an efficientcoral predator deterrent but they may nevertheless influence the dietary spectrum of C. austriacus.
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Herler Jürgen (2006): Morphological adaptations to microhabitats in coral-associated fishes: Oral presentation at ISRS (International Society for Reef Studies) Bremen (Sept. 2006).
There are numerous specialized fishes that exploit a variety of spatially restricted habitats in coralreefs, for example gobiids associated with living coral colonies. Coral-associated gobies belong tothe most habitat-specialized reef fish. In the Gulf of Aqaba (northern Red Sea), 21 species fromseven gobiid genera occupied corals or coral rock. The most specialized species (genera Gobiodon,Paragobiodon, Bryaninops and Pleurosicya) were associated with only a single coral species.Among the genus Gobiodon, which inhabits narrowly branched Acropora corals, three new specieswere discovered. Gobiid morphology was examined in respect to microhabitat structure. Bodyshape, pelvic fin development and eye indices were shown to be specialized features related tomicrohabitat characteristics. Geometric and traditional morphometrics showed high body shapevariation between species of Gobiodon, which favor different Acropora corals. Coral interbranchspace restricts fish body width and thus limits maximum fish size. Gobiodon histrio, for example,grows larger than congenerics due to allometric growth, yielding a highly compress body in largespecimens. Since body size plays a major role in the competitive hierarchy, such species aresuperior competitors and out-compete sister species. This study contributes to the explanation ofbody shape evolution and radiation in highly specialized reef fishes.
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Dirnwöber Markus & Herler Jürgen (2005): Microhabitat choice of selected Gobiodon species (Pisces: Gobiidae) in the Gulf of Aqaba, northern Red Sea. Poster presentation at 40th European Marine Biological Symposium, Vienna (Aug. 2005) and at European Congress of Ichthyology XII Dubrovnik (Sept. 2007).
Microhabitat preferences of gobiid fishes of the genus Gobiodon were studied in the northern Red Sea. These obligatory coral-dwelling fishes spend their life in corals of the genus Acropora, where most species form one monogamous breeding pair per colony. This study characterizes the spatial niche of selected Gobiodon species. We hypothesized that these fishes avoid competition by different patterns of habitat use. 1731 corals (13 species) hosting 1630 specimens of six Gobiodon species were censused at the reef flat, crest, slope and in the fore reef zone. The specialization indices of G. histrio, G. reticulatus, G. rivulatus and three as yet unidentified species (G. species 1, 2 and 3) varied remarkably. Each fish species occupied one to three coral species significantly more often than others. G. reticulatus inhabited the almost competition-free fore reef zone. Shifts in habitat use between juveniles and adults of five species indicated that intraspecific competition occurred for host corals, where adult breeding pairs are established. Nevertheless, abundances were maintained in substitute host corals characterised by low numbers of adult breeding pairs. Interspecific competition is limited among the six Gobiodon species by their patterns of microhabitat choice. Overlaps in habitat use occurred in three host corals only and did not involve more than two Gobiodon species per coral. Each of these gobies also used at least one other host coral that did not coincide with the preference of another Gobiodon. In particular, interspecific competition was unlikely to occur in any of the three cases due to different reasons: 1.) the coral species did not represent a limited resource, 2.) the fish species preferred different reef zones, 3.) the fish species co-existed within colonies without obvious interference. This study revealed that Gobiodon in the northern Red Sea can largely avoid interspecific competition by their pattern of microhabitat use. |
Herler Jürgen (2005): Inaccessible shallow-water habitats: a realm for marine gobiid dwarfs. Oral presentation at the 40th European Marine Biological Symposium. Vienna, August 2005.
Gobiid fish represent the most diverse marine fish family in the world and comprise almost 2000 species, including the smallest fish species known. Due to their small body size, gobies are able to exploit a variety of spatially restricted habitats. Submarine cave systems and coral reefs offer a wide variety of such microhabitats due to their complex physical structure. This supports a high diversity of gobiid species, for example in those associated with living coral colonies. Coral-associated gobies belong to the most habitat-specialized reef fish. These cryptic species require in situ investigations by SCUBA to be observed. In the Gulf of Aqaba (northern Red Sea) such examinations revealed 21 species from seven gobiid genera that were associated with corals and/or coral rock. Bryaninops yongei was exclusively found on the antipatharian Cirripathes sp., while its congener B. ridens prefers the hydrozoan Millepora dichotoma. Bryaninops natans and Pleurosicya prognatha were associated with scleractinian corals of the genus Acropora. Three as yet undetermined species of Gobiodon (G. sp.1 to 3) were found to be new for the Red Sea. Like their congeners G. citrinus, G. histrio, G. reticulatus and G. rivulatus, they are obligate occupants of Acropora. Paragobiodon echinocephalus only inhabited Stylophora pistillata. Massive coral growth forms were preferred by Pleurosicya micheli, Eviota guttata, E. sebreei and Trimma avidori. The latter was also frequently found on coral rock, in particular within overhangs, rocky caves and crevices. Trimma mendelssohni, Priolepis semidoliata, Eviota distigma, E. prasina and E. zebrina were common on coral rock, although the Eviota species also frequent live corals. This points to a clear spatial niche segregation, and co-occurrences of congenerics on the same coral are rare. Body shape, pelvic fin development and eye indices were shown to be specialized features related to microhabitat selection. Gobiodon species are characterized by a compressed and deep body, with a body depth at ventral fin origin (Vd) ranging from 38 to 44 % of standard length (SL). In contrast, the very depressed Bryaninops species had a Vd of 17 %SL. Fully developed, cup-shaped pelvic discs with a well-developed anterior membrane were only found in the coral-inhabiting genera Bryaninops, Pleurosicya, Paragobiodon and Gobiodon, having a remarkable suction function especially in the two former. In contrast, Trimma, Priolepis and Eviota exhibit incomplete pelvic discs or even separate ventrals without anterior membrane. The eye indices (eye diameter (E) in %SL) were related to the preferred water depth or to shaded microhabitats. Deeper-water species have a higher eye index than their sister species: B. natans (11.2) versus B. ridens (9.7) and G. citrinus (9.1) versus G. histrio (6.1). The highest value (11.5) was found in the cave-dwelling Trimma species, which show several analogies to another cave-dwelling goby of the Mediterranean Sea, Corcyrogobius liechtensteini. They are similar in coloration, pelvic fin development, behaviour and eye index, which can all be interpreted as independent adaptations to a similar life-style.
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Herler Jürgen, Stachowitsch Michael, Zolda Pamela & Waitzbauer Wolfgang (2003): Classroom Coral Reef: Practical marine ecology at the University of Vienna. Posterpresentation at the 1st Austrian Reef Workshop, Vienna, May 2003.
Abstract: For the past decade, the University of Vienna's Institute of Ecology and Conservation Biology has been conducting a 2-week field course in the coral reefs of the Red Sea at Aqaba, Jordan. The coral reef ecosystem offers the optimal setting to captivate and motivate students: a near-natural ecosystem, high biodiversity, mosaic of interrelated habitats (from seagrass meadows to sand flats), unparalleled species interactions (symbioses), visible human impacts.
A key challenge is to penetrate and gain insight into this complex ecosystem. The approach we use is to establish small teams of students to focus on specific topics. This is optimal from the educational standpoint because it cuts through the overwhelming complexity to achieve manageable goals; it also reflects the teamwork conditions that students can expect to encounter in their future careers.
The range of topics spans from methodological approaches to specific ecological and behavioral issues as well as monitoring efforts. Two basic types of studies can be conducted within such an annual two-week field course (with selected examples):
1. Short-term studies in which all necessary data are gained during the two-week period, e.g. topics basically dealing with the ecology or behavior of selected organisms (shrimp-goby associations, cleaner stations, movements of sea cucumbers, commensalism of fish, habitat choice of pomacentrid fish)
2. successive long-term studies that involve repeated investigations and rely on data from earlier years (coral growth, coral diseases, monitoring studies (Reef Assessment, ReefCheck, Coral Damage Index)
The multi-level course requires the students to familiarize themselves with every step of scientific inquiry:
a) understanding the theoretical framework (2-credit preparatory course prior to field course)
b) hypothesis formation
c) quantification: using a specific set of tools and skills (i.e. SCUBA diving, transect surveys, sampling methods, underwater photography) to obtain data in the field
d) analyzing and publishing results in the form of an annual report (basics of scientific writing, data processing and interpretation).
The information gained has significance beyond the education and training aspect: the reports are made available to local institutions and, for example in the case of reef health surveys, are of potential value in coastal management. Certain results obtained by student teams, staff members or participating researchers will be published in scientific journals. This multifaceted approach provides an optimal framework to attract potential sponsors, which would greatly benefit such cost-intensive courses.
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