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Diet composition of the Seahorses, Hippocampus guttulatus Cuvier, 1829 and Hippocampus hippocampus (L., 1758) (Teleostei, Syngnathidae) in the Aegean Sea

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Abstract

The diet composition of the European seahorses, Hippocampus guttulatus and Hippocampus hippocampus was determined based on the analysis of 279 and 19 specimens, respectively, collected in the Aegean Sea. The diet of both species was mainly based on Crustacea, with Amphipoda, Anomura Decapoda and Mysidacea being the dominant prey categories. ANOSIM analyses, however, indicated statistically significant differences in the diet of the two species as well as differences in the diet composition of non-brooding males, brooding males and females within each species. In H. guttulatus, stomach fullness percentages and vacuity coefficient values indicated that female individuals seem to have a higher feeding activity in relation to males.

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... Howard and Koehn 1985;Kendrick and Hyndes 2005), sex and reproductive status (e.g. D'Entremont 2002; Berglund et al. 2006;Kitsos et al. 2008), ontogenetics (e.g. Brown 1972Castro et al. 2008), habitat structure (e.g. Howard and Koehn 1985;Curtis and Vincent 2005;Kendrick and Hyndes 2005), and diurnal/seasonal variability (e.g. ...
... In addition, dozens of studies have catalogued syngnathid diets in the wild (e.g. Steffe et al. 1989;Gaughan and Potter 1997;Woods 2002;Kendrick and Hyndes 2005;Kitsos et al. 2008;Smith et al. 2011). ...
... Sex/reproductive status Among seahorses, the relationship between sex and reproductive status and feeding has been inconsistent, with some studies showing that females eat more than males (Kitsos et al. 2008), and others showing no difference (Woods 2002;Felicio et al. 2006;Storero and Gonzalez 2008;Gurkan et al. 2011b). Among H. reidi, adult males changed their diets and fed on smaller prey when they became reproductively active (Castro et al. 2008). ...
Article
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This review compiles, summarizes and provides new analytical insights on large amounts of fragmented information on the diets and feeding behaviours of syngnathids (Family Syngnathidae). This review is broken down into two distinct sections that address two central questions: (1) How, where, when and what do syngnathids eat? And (2) How does diet differ with feeding morphology? For (1) we summarized both qualitative and quantitative information on the diets and feeding behaviours of syngnathids found in the published and grey literature. This section includes a narrative summary of syngnathid feeding events and foraging behaviours (e.g. body mechanics and feeding morphologies, habitat use, seasonal and diurnal timing of feeding, energetics) and a tabulated summary of what syngnathids eat. For (2) we performed a comparative analysis on the diets of 41 species of syngnathid, comprising 15 genera from 39 sources in peer-reviewed and grey literature. Redundancy analyses on bulk, numeric, and frequency of occurrence data, analyzed separately, all show large unexplained dietary variation, which we hypothesize is the result of large differences in prey availability. Of the explained variation, syngnathid diets were most strongly correlated with head characteristics: most notably relative snout lengths and gape sizes. Syngnathid feeding morphologies also showed high phylogenetic signal; this suggests that dietary differences across genera were largely explained by how syngnathids differed with respect to these feeding morphologies. This review identifies new taxonomic patterns, and expands on previous generalities, improving our ecological understanding of this diverse group of fishes.
... It is possible that the method of prey sampling used in this study, in which prey items were collected from the surface of seagrass blades, did not represent the prey used by different age classes of seahorses. Although prey associated with the surface of plants are a major source of food for seahorses (Horinouchi & Sano, 2000;Teixeira & Musick, 2001;Kendrick & Hyndes, 2005;Kitsos et al., 2008;Storero & Gonzalez, 2008;Gurkan et al., 2011b), planktonic and epibenthic prey -not considered in this study -are important dietary items for smaller seahorses (Teixeira & Musick, 1995;Kanou & Kohno, 2001;Castro et al., 2008). For the scale of prey sampling in the present study (based on 0.25m 2 quadrats), however, the collection of planktonic prey was impractical. ...
... Syngnathid feeding mechanics have been the focus of numerous studies that investigated their structure, kinematics and evolutionary development (e.g. Bergert & Wainwright 1997;Van Wassenbergh et al., 2009 Kitsos et al., 2008), ontogenetics (e.g. Brown, 1972;Castro et al., 2008), habitat structure (e.g. ...
... In addition, dozens of studies have tabulated syngnathid diets in the wild (e.g. Steffe et al., 1989;Gaughan & Potter 1997;Woods, 2002;Kendrick & Hyndes, 2005;Kitsos et al., 2008;Smith et al., 2011a). ...
... Due to trophic functions and bioactive properties, syngnathid fishes are ecologically and commercially important 8 . These fishes mostly inhabit fragile ecosystems and productive coastal areas such as seagrass meadows, corals, mangroves as well as seaweeds 9 and feed on benthic organisms at the bottom-water column interface 10,11 . Previously, feeding ecology of few syngnathid fishes inhabiting the seagrass beds has been studied 10,11,12,13,14 . ...
... These fishes mostly inhabit fragile ecosystems and productive coastal areas such as seagrass meadows, corals, mangroves as well as seaweeds 9 and feed on benthic organisms at the bottom-water column interface 10,11 . Previously, feeding ecology of few syngnathid fishes inhabiting the seagrass beds has been studied 10,11,12,13,14 . ...
... Methods and formula described by various researchers were used for gut content analysis 10,23,36,37,38 . After taking length-weight measurements, fishes were dissected by incision at ventral surface and gut was carefully removed. ...
Article
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A total of 56 guts of the alligator pipefish, Syngnathoides biaculeatus collected from Palk Bay, southeast coast of India were analysed for determining its natural diet composition. The gut fullness index as assessed by point method showed that the majority of fish (71.43%) either had half-full (37.5%) or quarter-full guts (33.93%). Mean values of relative growth length (RGL) and gonado-somatic index (GSI) were estimated to be 0.36±0.03 and 3.78±1.67%, respectively. Copepods and sand particles occurred with 100% frequency of occurrence (%FO) followed by amphipods (%FO=99.25) isopods (%FO=86.79), peracarids (%FO=70.76) and decapods (%FO=65.28). The results of the gut content analysis showed that S. biaculeatus largely preyed on crustaceans (~90%) which included amphipods (40.36%), copepods (35.27%), decapods (8.12%), isopods (3.48%) and peracarids (2.21%). Consistent occurrence of sand particles and algal pieces in the guts reflect the feeding behaviour of S. biaculeatus in seagrass habitat over the sandy bottom. No significance difference in prey numbers and composition between male and female specimens was observed (P>0.05).
... Diet and foraging strategies are well documented in a large number of scientific studies that have shown that most seahorse species principally consume epibenthic invertebrates (e.g. harpacticoid copepods, nematodes, polychaetes), thus reflecting their sedentary behavior (Kendrick and Hyndes, 2005;Castro et al., 2008;Kitsos et al., 2008;Yip et al., 2015). In these studies, crustaceans have been considered as one of the main contributors to the seahorse diet (Foster and Vincent, 2004;Kendrick and Hyndes, 2005;Castro et al., 2008;Yip et al., 2015). ...
... Like most of its exotic congeners, the Mediterranean H. guttulatus primarily feed on Amphipoda, Anomura Decapoda and Mysidacea (Kitsos et al., 2008;Gurkan et al., 2011). However, because of the recent development of consolidated techniques that permitted to study gut contents through stable isotopes analysis (Valladares et al., 2017), the role of smaller prey without calcareous/chitinous exoskeleton (e.g. ...
... This sampling method allowed the study of epiphytic, epibenthic and endobenthic organisms, the most important prey items for H. guttulatus (Kitsos et al., 2008). Planktonic prey was not considered because of the difficulties in coupling sampled animals with specific habitats and the accuracy of the sampling procedure whose scale (cores) was not suitable for plankton. ...
Article
The present study examined the dietary composition of long-snouted seahorse H. guttulatus Cuvier, 1829 in Mar Piccolo of Taranto (Apulia, Italy)using a non-destructive flushing method. To assess differences in the selection of prey among different habitats, adult specimens were collected from both highly complex (Cladophora prolifera and Corallina elongata)and low complex (unvegetated Sandy bottom)habitats. Additionally, samples of benthic fauna were collected from the same habitats and were used to investigate the local availability of potential preys. Results showed significant differences in the diet composition among three studied habitats. Consistently with the results of faunal analysis, gut contents of specimens sampled on C. elongata had higher prey abundance and diversity compared to the other two habitats. Dietary composition of seahorses found in the vegetated habitats was similar, and it was mainly based on Amphipoda and Copepoda. However, small prey (<1 mm)was more consumed on C. elongata than on C. prolifera. On the sandy bottom, H. guttulatus preyed mainly on small crustaceans, but actively selected larger prey (i.e. Galathoidea and Paguroidea). Nematodes were also highly preyed in all habitats, although the high consumption could be possibly attributed to the high abundance and availability of these organisms at the investigated site. H. guttulatus showed a great ability to exploit available resources in the best possible manner among different habitats, acting as a specialist predator. With an aim to understand the use of food resources that are available in the environment, the results of this study could help to propose initiatives directed to the seahorse conservation. Since prey availability does not seem to be a limiting factor in the understanding of variability and consistency of H. guttulatus populations, further studies on other environmental and biological aspects could be useful in the assessment of the conservation status of long-snouted seahorses.
... Seahorses are flagship species to promote conservation programs, but despite the increasing worldwide concern over the conservation status of seahorses, there is a lack of detailed information about their feeding ecology, as well as other life history characteristics, which restricts the effectiveness of management strategies (Curtis and Vincent 2006). Seahorses are ambush predators, feeding primarily on live crustaceans, especially amphipods and decapods; however, information on specific dietary composition is limited to a few species, namely H. erectus (Teixeira and Musick 2001), H. abdominalis (Woods 2002), H. breviceps, H. subelongatus (Kendrick and Hyndes 2005), H. patagonicus (Storero and González 2008), H. hippocampus and H. guttulatus (Kitsos et al. 2008;Gurkan et al. 2011). The diet variability among adult seahorse species can be explained by their snout size and morphology, individual size, predation patterns or prey availability and abundance in their habitats (Tipton and Bell 1988;Woods 2002;Kendrick and Hyndes 2005). ...
... Seahorses are flagship species to promote conservation programs, but despite the increasing worldwide concern over the conservation status of seahorses, there is a lack of detailed information about their feeding ecology, as well as other life history characteristics, which restricts the effectiveness of management strategies (Curtis and Vincent 2006). Seahorses are ambush predators, feeding primarily on live crustaceans, especially amphipods and decapods; however, information on specific dietary composition is limited to a few species, namely H. erectus (Teixeira and Musick 2001), H. abdominalis (Woods 2002), H. breviceps, H. subelongatus (Kendrick and Hyndes 2005), H. patagonicus (Storero and González 2008), H. hippocampus and H. guttulatus (Kitsos et al. 2008;Gurkan et al. 2011). The diet variability among adult seahorse species can be explained by their snout size and morphology, individual size, predation patterns or prey availability and abundance in their habitats (Tipton and Bell 1988;Woods 2002;Kendrick and Hyndes 2005). ...
... Seahorses are ambush predators, feeding primarily on live crustaceans, especially amphipods and decapods; however, information on specific dietary composition is limited to a few species, namely H. erectus (Teixeira and Musick 2001), H. abdominalis (Woods 2002), H. breviceps, H. subelongatus (Kendrick and Hyndes 2005), H. patagonicus (Storero and González 2008), H. hippocampus and H. guttulatus (Kitsos et al. 2008;Gurkan et al. 2011). The diet variability among adult seahorse species can be explained by their snout size and morphology, individual size, predation patterns or prey availability and abundance in their habitats (Tipton and Bell 1988;Woods 2002;Kendrick and Hyndes 2005). Hence, feeding habits can vary among seahorse species and populations, which may become more or less vulnerable to environmental changes. ...
Article
The lack of integrated measures for assessing the feeding ecology of seahorses may restrict the effectiveness of conservation actions on wild populations of worldwide threatened seahorse species. Identifying dietary sources will allow researchers to determine their degree of vulnerability to environmental changes, redefine their conservation status and apply appropriate management strategies. The resource use of the seahorse Hippocampus guttulatus inhabiting coastal waters of Galicia (north-western Iberian Peninsula) was assessed for three populations and 2 years using stable isotope mixing models. The Bayesian mixing model (MixSIAR) estimated the relative contributions of the dietary sources to the seahorse diet and revealed that Caprellidea were the primary source, followed by Gammaridea and Caridea. Mysidae and Annelida represented the less dominant prey. This prey preference can be explained by the foraging behaviour of seahorses. Different contributions of Gammaridea and Caridea to the diet were found among sites, indicating different habitat characteristics and hence different habitat use by seahorses within each site. In addition, differences were encountered among sexes. Caprellidea was the dominant prey for females, whereas Gammaridea was the dominant prey for males. The findings of the present study will contribute to the knowledge of feeding patterns of H. guttulatus, providing relevant data for conservation of this endangered species.
... Diet and foraging strategies are well documented in a large number of scientific studies that have shown that most seahorse species principally consume epibenthic invertebrates (e.g. harpacticoid copepods, nematodes, polychaetes), thus reflecting their sedentary behavior (Kendrick and Hyndes, 2005;Castro et al., 2008;Kitsos et al., 2008;Yip et al., 2015). In these studies, crustaceans have been considered as one of the main contributors to the seahorse diet (Foster and Vincent, 2004;Kendrick and Hyndes, 2005;Castro et al., 2008;Yip et al., 2015). ...
... Like most of its exotic congeners, the Mediterranean H. guttulatus primarily feed on Amphipoda, Anomura Decapoda and Mysidacea (Kitsos et al., 2008;Gurkan et al., 2011). However, because of the recent development of consolidated techniques that permitted to study gut contents through stable isotopes analysis (Valladares et al., 2017), the role of smaller prey without calcareous/chitinous exoskeleton (e.g. ...
... This sampling method allowed the study of epiphytic, epibenthic and endobenthic organisms, the most important prey items for H. guttulatus (Kitsos et al., 2008). Planktonic prey was not considered because of the difficulties in coupling sampled animals with specific habitats and the accuracy of the sampling procedure whose scale (cores) was not suitable for plankton. ...
Article
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The data presented here support research article entitled 'Trophic flexibility and prey selection of the wild long-snouted seahorse Hippocampus guttulatus Cuvier, 1829 in three coastal habitats'' Ape et al., 2019. Determinations of the dietary composition, differences in prey selection and potential prey abundance and availability among three habitats at Taranto Mar Piccolo were based on the analysis of gut contents of seahorses and sediment samples. Both highly (Corallina elongata and Cladophora prolifera) and low complex (sandy bottom) habitats were investigated. Prey items were divided into two size classes: <1 mm and >1mm. Data about the total abundance of each prey size class in gut contents and sediments in three different habitats and PERMANOVA comparisons are given.
... A maior parte dos informantes relata que os cavalos-marinhos se alimentam de "sujeirinha" da água (correspondente ao que se denomina na linguagem científica como plâncton), da lama ou que fica aderida às raízes do mangue. Um dos informantes destaca ainda que, além dessa "sujeirinha", eles também comem "ova de peixe", sendo este último item citado na dieta de Hippocampus gutullatus e H. hippocampus (Kitsos et al. 2008). Nos estuários dos rios Mamanguape, Pacoti, Acarau, no Braço-de-mar de Porto dos Barcos e Itapessoca, os pescadores forneceram detalhes sobre o tipo de alimento, referindo-se a "fiação de peixes" (alevinos) e "filhotes de camarão" (pequenos camarões e microcrustáceos) e ao comportamento trófico desses peixes, conforme o depoimento de um dos entrevistados do estuário do rio Mamanguape: "o cavalo-marinho dá um chupo nos filhote de camarão com o negócio comprido (focinho), aí faz um estralo e depois engole". ...
... Este capítulo consiste em uma versão adaptada de trabalho previamente publicado emRosa et al. (2005): Fishers' knowledge and seahorse conservation in Brazil. Journal of Ethnobiology and Ethnomedicine 5(23). ...
Chapter
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Cavalos-marinhos são peixes ameaçados de extinção devido a sua intensa exploração comercial e à degradação ambiental. Dentro de uma perspectiva social, a sua pesca direta representa uma fonte de renda em algumas comunidades pesqueiras. A integração entre esses dois aspectos passa pelo reconhecimento de que pescadores apresentam uma série de conhecimentos e habilidades que podem auxiliar quando da implementação de planos de manejo os cavalos-marinhos e seus ambientes. Neste capítulo apresentam-se informações acerca da percepção de pescadores ocasionais ou intencionais de cavalos-marinhos do Norte e Nordeste do Brasil sobre a biologia e ecologia do cavalo-marinho Hippocampus reidi, no sentido de que o conhecimento ecológico por eles detido e o contexto sócio-econômico em que vivem sejam considerados nas ações de conservação e em estratégias de manejo.
... However, recent studies argue that large individuals contribute to reproduction so that selectivity for large individuals may negatively affect fish population [21]. Multi species predominated small-scale fisheries in developing countries where size limits are complicated [22]. Legal size can be confusing for fishers. ...
... Information on fish diet in the wild provide clues on the species nutritional requirements, interaction with other organisms and use to formulate fish feed under culture environment [22]. Quantitative and qualitative estimation of gut contents carried out in this study reveals that the African snakehead feed on twelve food items in Eleyele Lake but the most balanced feeding regime consists of fishes, insect parts, diatoms and earthworms. ...
Conference Paper
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–Parachanna obscura is an economically valuable freshwater fish with potential for recruitment into aquaculture in Nigeria. Information on the food and feeding habits of fish in the wild is a prelude to bring it to culture but such is currently scarce for P. obscura. Therefore, this study investigates the gut morphometric parameters and gut contents of P. obscura in Eleyele Lake. 688 samples were obtained from fisher’s catch fortnightly for 24 months. Relative Gut Length (RLG), Gastro-Somatic Index (GaSI), Gut Fullness and Gut Contents Analysis were determined following standard procedures. Data were analyzed using descriptive and inferential statistics at α0.05. Significant correlation was observed between gut length and total body length (r = 0.513, p<0.05). Also, RLG, was highest in size group 12.1 – 15.0cm and lowest in size group 42.1 – 45.0cm for both sexes. GaSI indicated higher rate of feeding among males (1.70±0.46 – 5.25±1.08) than the female (1.44±0.19 – 4.32±2.50). Empty guts were higher between November to December and February to March in males and July, September and October in female. However, full guts peaked in May for both sexes. Fish (49.22%) constituted the major food items in the gut. Gut contents analysis revealed P. obscura as a carnivore and opportunistic feeder. Key words: African snakehead, Gut contents, Carnivore, Aquaculture
... Seahorses usually practice a "sit-and-wait" predation strategy when they wait for prey from a hidden position and then launch a rapid surprise attack [20]. By employing morphological examination of gut or stomach contents, through stomach flushing or by biochemical means, studies on their diet have shown that seahorses feed mainly on smallsized crustaceans, such as Amphipoda, Decapoda, and Anomura [20][21][22][23]. A recent study based on morphological examination of stomach contents revealed the presence of only a few soft-bodied prey items, such as nematodes [20]. ...
... Observation of crustaceans as dominant prey is in congruence with previous studies, based on conventional morphological identification methods [20][21][22], although from a taxonomic point of view, the present results were more accurate and consistent in terms of the identified taxa. Despite the small number of feces analyzed (n = 9), the DNA metabarcoding approach corroborates and provides additional resolution to results from these studies. ...
Article
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Seahorses are considered a flagship species for conservation efforts and due to their conservation status, improving knowledge on their dietary composition while applying a non-invasive approach, could be useful. Using Hippocampus guttulatus as a case study, the present study represents pioneering research into investigating the diet of seahorses by NGS-based DNA metabarcoding of fecal samples. The study developed and tested the protocol for fecal DNA metabarcoding during the feeding trials where captive seahorses were fed on a diet of known composition; the process was subsequently applied on fecal samples collected from wild individuals. The analysis of samples collected during the feeding trials indicated the reliability of the applied molecular approach by allowing the characterization of the effectively ingested prey. In the field study, among detected prey species, results revealed that the majority of the seahorse samples contained taxa such as Amphipoda, Decapoda, Isopoda, and Calanoida, while less common prey taxa were Gastropoda and Polyplacophora. As only a small amount of starting fecal material is needed and the sampling procedure is neither invasive nor lethal. The present study indicates DNA metabarcoding as useful for investigating seahorse diet and could help define management and conservation actions.
... En cuanto a las dos especies de Andalucía, H. guttulatus consume mayoritariamente decápodos (zoeas), misidáceos y anfípodos, con una frecuencia de aparición en los estómagos del 100%, 85,71% y 47,62% respectivamente (Kitsos et al., 2008;Gurkan et al., 2011). Por su parte, H. hippocampus tiene un dieta más diversa, ocupando los anfípodos el segundo puesto de importancia (frecuencia del 21,05%) detrás de los decápodos (larvas) (frecuencia del 26,32%) (Kitsos et al. 2008;Gurkan et al., 2011). ...
... En cuanto a las dos especies de Andalucía, H. guttulatus consume mayoritariamente decápodos (zoeas), misidáceos y anfípodos, con una frecuencia de aparición en los estómagos del 100%, 85,71% y 47,62% respectivamente (Kitsos et al., 2008;Gurkan et al., 2011). Por su parte, H. hippocampus tiene un dieta más diversa, ocupando los anfípodos el segundo puesto de importancia (frecuencia del 21,05%) detrás de los decápodos (larvas) (frecuencia del 26,32%) (Kitsos et al. 2008;Gurkan et al., 2011). Los anfípodos son de gran importancia en varias especies alóctonas de caballitos de mar que podrían ser cultivadas en circuitos cerrados, junto con las especies autóctonas de Andalucía. ...
... They ambush small prey in complex habitats and show a variety of diets and foraging behaviors across genera and locations (Manning et al. 2019), depending on species, mouth type, gender, season, habitat and prey availability (Dawson 1986, Franzoi et al. 1993, Roelke & Sogard 1993, Teixeira & Musick 1995, Foster & Vincent 2004, Vizzini & Mazzola 2004, Castro et al. 2008. Generally, several taxa of crustaceans and other invertebrates (including meroplankton) in the water column, vegetation or among detritus on the substrate are preferred (Bennett 1989, Kendrick & Hyndes 2005, Oliveira et al. 2007, Kitsos et al. 2008, Taşkavak et al. 2010, Valladares et al. 2017, Nenciu et al. 2018, Ape et al. 2019, Gürkan & Taşkavak 2019. However, amphipods and copepods are among the preferred prey for many species (Bennett 1989, Kitsos et al. 2008, Taşkavak et al. 2010, Gürkan & Taşkavak 2019, Manning et al. 2019. ...
... Generally, several taxa of crustaceans and other invertebrates (including meroplankton) in the water column, vegetation or among detritus on the substrate are preferred (Bennett 1989, Kendrick & Hyndes 2005, Oliveira et al. 2007, Kitsos et al. 2008, Taşkavak et al. 2010, Valladares et al. 2017, Nenciu et al. 2018, Ape et al. 2019, Gürkan & Taşkavak 2019. However, amphipods and copepods are among the preferred prey for many species (Bennett 1989, Kitsos et al. 2008, Taşkavak et al. 2010, Gürkan & Taşkavak 2019, Manning et al. 2019. ...
Article
Syngnathids are vulnerable ovoviviparous fishes with repeated brooding of males within a reproductive season. The isotopic effects of diet on both breeders (pooled sexes) and parent–egg transmission have been demonstrated in a few fish species but never in syngnathids. Quantifying isotopic changes due to diet is necessary to assess parent–newborn conversions and to estimate accurate trophic enrichment factors (TEF). We assessed the isotopic (δ13C and δ15N) effects of 3 experimental diets on TEFs in seahorse Hippocampus guttulatus breeders and isotopic inheritance. Our results suggest that H. guttulatus follows an income-capital continuum pattern for parent–egg transmission. The isotopic variability in diets for breeders and the resulting experimentally derived TEFs were compared with fixed TEFs from reviews to estimate their impact on the relative contribution of potential prey sources in syngnathids from Cíes archipelago (Atlantic Islands National Park, NW Spain). We estimated source contributions using stable isotopes mixing models (SIMMs) by combining prey sources into ecologically informative groups and incorporating informative priors. We demonstrate that (1) most frequently used TEFs from reviews might not be suitable to all fish species, particularly to syngnathids, and (2) dietary source variability has a great effect on source contribution estimates. This study is also the first to provide specific TEFs for syngnathids.
... As most ecological studies of seahorses in Europe have used the nomenclature of H. hippocampus and H. guttulatus to define their focal species (e.g. Curtis and Vincent 2005;Kitsos et al. 2008;Ben Amor et al. 2011;Caldwell and Vincent 2012;Filiz and Taskavak 2012;Gristina et al. 2015), there is some consensus for a conservative view of seahorse taxonomy. Some reports also suggest range extensions into European waters by non-native species: H. algiricus presence in the Canary Islands (Otero-Ferrer et al. 2015b, the Lessepsian migrant H. fuscus in the eastern Mediterranean (Golani and Fine 2002), and occasional rare migrants (e.g. ...
... The differences in abundance observed between the two species suggest different conditions are required for these species to thrive, but these exact parameters are yet to be determined. Niche partitioning is expected in congeneric species, and further observations to determine any differences in prey items (Kitsos et al. 2008), morphology and behaviour would be an interesting contribution to determine how management measures differentially impact the two species. ...
Article
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Accurate taxonomy, population demography, and habitat descriptors inform species threat assessments and the design of effective conservation measures. Here we combine published studies with new genetic, morphological and habitat data that were collected from seahorse populations located along the European and North African coastlines to help inform management decisions for European seahorses. This study confirms the presence of only two native seahorse species (Hippocampus guttulatus and H. hippocampus) across Europe, with sporadic occurrence of non-native seahorse species in European waters. For the two native species, our findings demonstrate that highly variable morphological characteristics, such as size and presence or number of cirri, are unreliable for distinguishing species. Both species exhibit sex dimorphism with females being significantly larger. Across its range, H. guttulatus were larger and found at higher densities in cooler waters, and individuals in the Black Sea were significantly smaller than in other populations. H. hippocampus were significantly larger in Senegal. Hippocampus guttulatus tends to have higher density populations than H. hippocampus when they occur sympatrically. Although these species are often associated with seagrass beds, data show both species inhabit a wide variety of shallow habitats and use a mixture of holdfasts. We suggest an international mosaic of protected areas focused on multiple habitat types as the first step to successful assessment, monitoring and conservation management of these Data Deficient species. Electronic supplementary material The online version of this article (10.1007/s00227-017-3274-y) contains supplementary material, which is available to authorized users.
... It is possible that the method of prey sampling used in this study, in which prey items were collected from the surface of seagrass blades, did not represent the prey used by different age classes of H. whitei. Although prey associated with the surface of plants are a major source of food for seahorses (Gurkan et al., 2011;Horinouchi & Sano, 2000;Kendrick & Hyndes, 2005;Kitsos et al., 2008;Storero & Gonzalez, 2008;Teixeira & Musick, 2001), planktonic and epibenthic prey, which were not considered in this study, are important dietary items for smaller seahorses (Castro et al., 2008;Kanou & Kohno, 2001;Teixeira & Musick, 1995). However, given the scale of prey sampling in the present study (based on 0.25 m 2 quadrats), the collection of planktonic prey was impractical. ...
Article
Analysing the associations between the endangered White's seahorse Hippocampus whitei and characteristics of its environment (including habitat, prey and predator variables) in an estuary in New South Wales, Australia, revealed that seahorses had a greater number of significant associations with environmental correlates within a single seagrass bed than among seagrass beds. Predator abundance was negatively correlated with H. whitei abundances among seven seagrass beds (200–6000 m apart) and no ecological correlate was associated with H. whitei body size distributions. Within the seagrass bed with the greatest number of H. whitei , individuals preferentially selected locations that were deeper, had denser seagrass, more epiphytic prey types and fewer predators. Smaller H. whitei were associated with greater depths within the bed. In this study, each class of ecological correlate (habitat, prey, predators) was found to have at least one significant relationship with H. whitei , depending on the scale, demonstrating that all three are important to H. whitei populations. As such, future studies that evaluate animal populations may benefit from holistic approaches that consider each of these together. For animals that are experiencing dramatic population declines due to habitat destruction, as H. whitei has over the last decade, a better understanding of its relationship to its environment is important to inform conservation action. This article is protected by copyright. All rights reserved.
... The natural diet of most seahorses species consists of amphipods and copepods (Gurkan et al., 2011;Kitsos et al., 2008;Koldewey and Martin-Smith, 2010;Storero and Gonzalez, 2009;Teixeira and Musick, 2001;Valladares et al., 2017), and amphipods have been attracting interest as an alternative natural food in aquaculture (Baeza-Rojano et al., 2013aWoods, 2009) mainly because their culture may be easier and cheaper than commonly used foods. Most amphipod species are detritivores, and despite their low fecundity, they have high reproduction and growth rates due to relative large embryos and parental care and reproductive strategies that are generalized throughout the group (Woods, 2009). ...
... Therefore, alternative prey, other than rotifers and Artemia, are explored with great interest by the scientific community (Calado et al., 2017). In the wild, adult seahorses feed on a variety of prey (mostly crustaceans) (Teixeira and Musick, 2001;Woods, 2002;Kendrick and Hyndes, 2005;Kitsos et al., 2008;Storero and González, 2008;Gurkan et al., 2011;Valladares et al., 2017), including copepods (Tipton and Bell, 1988;Franzoi et al., 1993) but the natural diet of young seahorses is still unknown. It has been reported that feeding young pipefish and seahorses on cultured copepods may significantly improve survival rates and growth (Payne et al., 1998;Payne and Rippingale, 2000;Olivotto et al., 2008a;. ...
Article
Larval nutrition plays a key role in the development of a sustainable aquaculture where fish development, health and wellness are of prime importance. For some species, satisfactory growth and survival rates are met providing exclusively enriched rotifers and Artemia; however, feeding on copepods during the larval period has been shown to improve growth in both larval and juvenile fish, including seahorses. For the first time, the effects of different diets (Artemia and copepods) on the early development of juvenile seahorses (H. guttulatus and H. reidi) development were analysed by combining biometry, traditional histology and FPA-FTIR Imaging spectroscopy. Survival and growth and biochemical composition on the liver in seahorse were significantly affected by the type of diet offered. The results achieved were related to differences in the digestion of the two types of live preys, mainly dependent on their biochemical composition and permeability of the exoskeleton.
... The gut fullness (ca. percentage fullness) was determined visually for each specimen according to Kitsos et al. (2008). The fullness scale ranged from 0% to 100% with empty as empty (0%), moderately full (25%), half full (50%), quite full (75%), and very full (100%). ...
Article
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Mazlum R.E., Şahin C. 2017. Age, growth, gonadosomatic index and diet composition of Crimean barbel, Barbus tauricus (Actinopterygii: Cypriniformes: Cyprinidae), in a small Stream in NE Turkey. Acta Ichthyol. Piscat. 47 (4): 339-346. Background. Crimean barbel, Barbus tauricus Kessler, 1877, is a riverine cyprinid fish commonly found in well-oxygenated streams with gravel bottom in the Black and Azov Sea basins. Its population has plummeted in the Salgir, Chornaya, and Alma rivers (Crimea) and hence this fish has been listed as Vulnerable on the IUCN Red List. The knowledge about its age, growth, length-weight relation, spawning period, and diet composition are either scarce or not available. This paper aimed to fill the existing gaps in the knowledge by describing selected biological characteristics of B. tauricus in the Çiftekavak Stream, in the outskirts of the city of Rize, NE Turkey. Materials and methods. Crimean barbel were collected by electrofishing (60 Hz pulsed DC) from April to November 2014. The total length (L, cm) and weight (W, g) of each specimen were recorded, and sagittal otoliths, gonads, and gut contents were then recovered. The length-weight relation (LWR) was calculated by a simple power function W=aL b. The age rings on sagittal otoliths were counted to determine fish age that was later used to analyse their growth by various growth models. The wet weight of gonads was used to calculate the gonadosomatic index (GSI). The gut contents were identified to the lowest possible taxonomic level and the contribution of a prey in the total diet composition was analysed by the occurrence frequency of prey groups (%O) and by numerical percentage frequency of prey groups (%N). Results. The age ranged from 0 to 4 years and more than 50% of the fish represented the 0-year group followed by 1-year group (21.9%) and 2-year group (13.5%). The von Bertalanffy growth model adequately described the correlation between the fish length and the age and indicated that females grew faster than males. The LWR identified negative allometric growth patterns in males and females. The higher values of GSI from males and females were recorded from April through July, while the lowest value of GSI was observed from September through November indicating the completion of the spawning season. A total of 14 prey items (including sand grains) were identified from the guts of Crimean barbel. The main prey items were Culex sp. (larva + pupa + adult), Chironomidae, followed by Ephemeridae and Zygoptera. They constituted up to >78%O (>95%N) of the diet. Conclusions. The results of this study will assess the conservative regulations and policies that will eventually provide a sustainable management of Crimean barbel stocks.
... At Taranto Mar Piccolo, and especially for H. guttulatus, specimens longer that 120 mm have never been recorded, even though more than 150 individuals have been measured. This finding strongly disagrees with data from the literature, which report adult individuals of up to 215 mm in the Atlantic Ocean (Curtis, Ribeiro, Erzini, & Vincent, 2007) and 225 mm in the Mediterranean Sea (Kitsos, Tzomos, Anagnostopoulou, & Koukouras, 2008;Woodall et al., 2018). At the other sites examined here, the maximum sizes of individuals fit with the literature data. ...
Article
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• The aim of this study was to provide further knowledge of the ecological, spatial, and temporal distribution and life‐cycle traits of the sympatric seahorse species Hippocampus hippocampus and Hippocampus guttulatus. • From 2011 to 2014, data were collected from 20 sites along the Apulian coast (Southern Italy) in order to cover a wide range of coastal marine, open water, and lagoon sites, from the surface to a depth of 48 metres. • Seahorses were found at seven of the 20 sites investigated. Both species displayed temporal persistence, patchy distribution, and a high spatial demographic heterogeneity. • This study revealed a smaller maximum size and size at maturity of H. guttulatus than has been reported elsewhere. Although it is possible that environmental factors are influencing the size of these animals, there may be genetic explanations, especially for lagoon populations. • Despite the fragmented distribution and often low abundance found along the Apulian coast, some seahorse populations appear to be locally persistent and stable over time, suggesting that there is a need for appropriate location‐specific conservation strategies. • Not just maintaining but increasing the area of artificial substrates, which enhance habitat complexity and provide holdfasts, could represent a possible approach to help conserve marine littoral biodiversity and to protect endangered species in lagoons.
... The objective of this study is to describe a methodology for the grass shrimp culturing with the aim of producing an alternative prey for feeding juveniles and adult seahorses, namely Hippocampus guttulatus. Kitsos et al. (2008) reported a diet mainly based on Crustacea in wild seahorses H. guttulatus and H. hippocampus. ...
Conference Paper
Full-text available
The culture of the grass shrimp Palaemonetes varians for feeding purposes was not addressed until now. Information was almost lacking in this species. although partial information was provided by Yúfera and Rodríguez (1985) and Calado et al. (2010;). This study provides useful information on ongrowing diets, female maturation and biochemical composition for the use of grass shrimp as live prey for cultured fishes.
... where n is the number of fish of a particular food type, N s is the total number of fish containing food in their stomach, is the total number of prey in a food group, and N p is the total number of all prey groups. The stomach fullness was determined visually according to Kitsos et al. (2008) using a scale ranging from 0 to 100% with empty as (0%), moderately full (25%), half full (50%), quite full (75%) and very full (100%). ...
Article
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The diet of the European anchovy Engraulis encrasicolus was studied in the southeast Black Sea region of Turkey during the autumn, winter and spring seasons. Examination of the stomach contents of 526 specimens (total length ranging from 6.9-13.8 cm) confirmed that E. encrasicolus is a zooplanktivorous fish species. Among the 38 identified prey items, 71% were classified as zooplankton. The predominant prey groups of the zooplankton were fish eggs and larvae, and Ctenophorans followed by copepods. Data analysis revealed significant differences in the prey species composition between different seasons (ANOSIM, R = 0.229, p < 0.001) and between fish length classes (ANOSIM, R = 0.073, p < 0.001). The prey species that constituted the majority of the diet changed significantly with the season. SIMPER analysis revealed that the prey item contributing the most to the differences between seasons and length classes was fish eggs. The results of this study could be used to describe the diversity of prey species and intraspecific food competition in the Black Sea.
... In captivity, adult seahorses show preference for mysids and amphipods (Vite et al. 2009). In fact, these are their preferred prey in the wild as well (Teixeira and Musick 2001;Kitsos et al. 2008). Adult Artemia promotes high growth rates in seahorses (Planas et al. 2009c), but its nutritional adequacy, in terms of reproductive efficiency, has been often questioned. ...
Book
The global trade of aquatic organisms for home and public aquariums, along with associated equipment and accessories, has become a multi-billion dollar industry. Aquaculture of marine ornamental species, still in its infancy, is recognized as a viable alternative to wild collection as it can supplement or replace the supply of wild caught specimens and potentially help recover natural populations through restocking. This book collects into a single work the most up-to-date information currently available on the aquaculture of marine ornamental species. It includes the contributions of more than 50 leading scientists and experts on different topics relevant for the aquaculture of the most emblematic groups of organisms traded for reef aquariums. From clownfish, to angelfish, tangs and seahorses, as well as corals, anemones, shrimps, giant clams and several other reef organisms, all issues related with the husbandry, breeding, and trade are addressed, with explanatory schemes and illustrations being used to help in understanding the most complex topics addressed. Marine Ornamental Species Aquaculture is a key reference for scientists and academics in research institutes and universities, public and private aquaria, as well as for hobbyists. Entrepreneurs will also find this book an important resource, as the culture of marine ornamental species is analyzed from a business oriented perspective, highlighting the risks and opportunities of commercial scale aquaculture of marine ornamentals.
... Hippocampus hippocampus [519] (Linnaeus, 1758) ...
Data
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Number of cannibalism cases obtained in the literature search, with species feeding habit of the adult stage and countries where studies were conducted. ‘Total papers’ refers to the number of papers consulted for each species regardless of the presence or absence of cannibalism. Feeding habit: Inv- Invertivorous, Omn–Omnivorous, Pis–Piscivorous, and Zoo–Zooplanktivorous. (PDF)
... In captivity, adult seahorses show preference for mysids and amphipods (Vite et al. 2009). In fact, these are their preferred prey in the wild as well (Teixeira and Musick 2001;Kitsos et al. 2008). Adult Artemia promotes high growth rates in seahorses (Planas et al. 2009c), but its nutritional adequacy, in terms of reproductive efficiency, has been often questioned. ...
Chapter
Syngnathids, particularly seahorses, have long fascinated humans. Surprisingly, their biology and ecology is still poorly known. That is probably one of the reasons why reared fishes of these species have only recently been introduced into the aquarium trade. Currently, rearing techniques are available for a dozen seahorse species and for a few ornamental pipefishes. Even though the morphology of all these species is rather similar, their biology and rearing requirements largely differ among species. As a result, the methodological procedures for cultivation must be studied and assessed explicitly for each species. Noteworthy survivals have been achieved for some species but there is a need for optimization of rearing techniques, and increased knowledge in many aspects including breeding, nutritional requirements and diseases. This chapter is focused on general aspects of the biology of seahorses and pipefishes and on current knowledge of their rearing techniques. Data sheets on the rearing requirements for selected seahorse and pipefish species are also provided, as well as for seadragons.
... Seahorses, which belong to the family Syngnathidae, are ovoviviparous fish whose embryos can obtain paternal nutrients during pregnancy through the male's brood pouch and maternal nutrients from yolk (Foster and Vincent, 2004; Wilson et al., 2001). Seahorses mainly feed on planktonic crustaceans, such as copepods, amphipods, decapods and mysid shrimps (Kitsos et al., 2008; Lin et al., 2009; Lin et al., 2010). However, sometimes seahorses might have to endure starvation because of their slow swimming ability and the patchiness of prey distribution and abundance when they are taken to a new place by water current in the wild, which often leads to high mortality, especially during the juvenile seahorse stage (Lourie et al., 1999; Vincent et al., 2011). ...
Article
Leptin is an essential hormone for the regulation of energy metabolism and food intake in vertebrate animals. To better understand the physiological roles of leptin in nutrient regulation in paternal ovoviviparous fish (family Syngnathidae), the present study cloned the full-length of leptin-a and leptin receptor (lepr) genes in lined seahorse Hippocampus erectus Results showed that there was a 576-bp intron between two exons in leptin-a gene but no leptin-b gene in seahorse. Although the primary amino acid sequence conservation of seahorse leptin-a was very low, the 3-D structure modeling of seahorse leptin-a revealed strong conservation of tertiary structure with other vertebrates. Seahorse leptin-a mRNA was highly expressed in brain, whereas lepr mRNA was mainly expressed in ovary and gill. Interestingly, both leptin-a and lepr mRNA were expressed in the brood pouch of male seahorse, suggesting leptin system plays roles during the male-pregnancy. Physiological experiments showed that the expression of hepatic leptin-a and lepr mRNA in unfed seahorses was significantly higher than that in those fed 100% as well as 60% of their food during fasting stage, showing that seahorse might initiate the leptin system regulate its energy metabolism while starving. Moreover, the expression of leptin-a in brood pouch of pregnant seahorse was significantly upregulated compared with non-pregnant seahorse, whereas the expression of lepr was downregulated, suggesting that leptin system might be involved in the male-pregnancy. In conclusion, the leptin system plays roles in the energy metabolism and food intake and might provide new insights into molecular regulation of male-pregnancy in seahorse.
... Adult individuals (both males and females) preferentially use the Poles With Soft Bottom (PWSB) and Cladophora prolifera beds (CLAD) (Fig. 4). PWSB is a complex habitat that provides many suitable microhabitats used for camouflaging and it is a good source of amphipods and copepods, regarded as the main prey of seahorses (Kitsos et al., 2008;Kuiter, 2009). Unlike PWSB, the CLAD habitat, due to its rapid turnover, can be considered as a habitat of low complexity, which gives rise to a rich detritus food chain by supporting an abundant population of crustacean detritivores. ...
Article
Full-text available
Understanding of the spatial distribution and habitat use in different stages of a life cycle represents the essential aspect of threatened species management and conservation. In the present paper, the spatial and temporal patterns of habitat use in juvenile and adult life stages of the long-snouted seahorse Hippocampus guttulatus in the Mar Piccolo of Taranto (Apulia—Italy) (40°28′N, 17°16′W) were examined. From October 2012 to January 2014, monthly visual censuses were conducted in six coastal habitats of a focal area (Buffoluto site). Of a total of 317 individuals of the long-snouted seahorse that were sighted, 148 were juveniles, 82 adult females and 87 adult males. Our results showed significant differences in the habitat use between adult and juvenile life stages of H. guttulatus. Adult individuals were mainly concentrated within Cladophora prolifera beds and the wood poles of a mussel farm at 2–4 m of depth, while juvenile individuals were mainly present in shallower water (0.4–1 m) on artificial hard substrates covered by a brown algae turf. Assessing and describing the habitat use within different life stages of H. guttulatus represent a useful tool to support species conservation by protecting the habitats it uses.
... The study of natural diets of fish species is very useful approach for understanding aspect of the species biology and ecology, towards a more sustainable management of their stocks and the development of conservation measures (La Mesa et al., 2007;Kitsos et al., 2008). ...
Article
This study was carried out to describe the feeding habits of Scorpaena porcus and to investigate the effect of sex, size and season on their diet. Within the framework of this study, food preferences of 262 Scorpaena porcus (13+/-0.26 cm; 67+/-3.46 g) (+/-SE of means) which were taken from the stomach contents of fish caught at Trabzon coast (located at the South - Eastern Black Sea coast, between November 2003 and January 2004) were investigated. Scorpaena porcus fed mainly upon red mullet (Mullus barbatus) (IRI%=34.67) and mud shrimp (Upogebia pusilla) (IRI%=28.10), but also upon harbour crab, brown shrimp, sea horse, and others. It was found that there were significant differences between its dietary habits in summer and winter times (chi(2)=38.10, P<0.01). Scorpaena porcus, fed mainly upon harbour crab (IRI%=63.43) in summer and red mullet (IRI%=57.46) in winter. As a result of statistical evaluation, red mullet, harbour crab and sea horse were found statistically significant in their seasonal diet (P<0.05).
... Mide doluluk oranı, boş (%0), az dolu (%25), yarı dolu (%50), oldukça dolu (%75) ve tam dolu (%100) olarak 5 kategoriye ayrılmıştır (Kitsos ve ark., 2008). Boşluk indeksi (Vacuity index, VI), boş midelerin toplam incelenen örnek sayısına yüzde oranı olarak ifade edilmektedir ve aşağıdaki formül ile hesaplanmaktadır (Berg, 1979); VI = (Boş mide sayısı / Toplam mide sayısı) x 100 (1) ...
Article
Full-text available
Araştırma Makalesi / Research Article ÖZET: Çanakkale sığ sularında (<2m) yapılan bu çalışmanın ana amacı, genç mırmır, Lithognathus mormyrus (Linneaus, 1758), bireylerinin beslenme alışkanlıklarının tespit edilmesidir. Bu amaçla, Ocak ile Aralık 2007 tarihleri arasında ığrıp örneklemeleri ile 6 farklı istasyondan elde edilen toplam boyları 33–125 ± 0.18 mm arasında olan 113 adet genç mırmır bireylerinin mide içerikleri incelenmiştir. Bu bireylerin 16 (%14.16) adetinin midesinde besinsel organizmaya rastlanılmamıştır. Toplam IRI değerlerine göre, genç mırmır bireylerinin ana besinlerinin copepod (%IRI = 91.19) olduğu ve diğer başlıca besin kaynaklarının da sırasıyla foraminifera (%IRI = %1.98), peracaridea (%IRI = %1.60), cumacea (%IRI = %1.50), amphipoda (%IRI = %0.75) ve mollusca (%IRI = %0.11) olduğu belirlenmiştir. Besin tercihlerinin mevsimsel olarak değişip değişmediğini tespit etmek amacıyla ANOSIM istatistik testi uygulanmış ve önemli derecede fark bulunamamıştır (ANOSIM: R = 0.24, P > 0.05). ABSTRACT: The main purpose of this study was to determine feeding habits of young of the year striped sea bream, Lithognathus mormyrus (Linnaeus, 1758) from Canakkale shallow waters (<2m). With this purpose, stomach contents of 113 specimens, total length from 33 to 125 ± 0.18 mm, collected by beach seine from January to December 2007, from 6 different sampling locations, were analyzed. The overall percentages of empty stomachs were 14.16%. Based on the IRI analysis, among the main prey categories copepod (%IRI = 91.19) was the most preferred food group, followed by foraminifera (%IRI = %1.98), peracaridea (%IRI = %1.60), cumacea (%IRI = %1.50), amphipoda (%IRI = %0.75) and mollusca (%IRI = %0.11). No significant differences were found among the seasons (ANOSIM: R = 0.24, P > 0.05) in terms of nutrient preference.
... Colouration can be brown, orange, purple or black, sometimes with small white spots [45]. H. hippocampus feeds on zooplankton and small crustaceans [98]. This species is found in shallow inshore waters and littoral lagoons often in Zostera and Posidonia beds. ...
Technical Report
Full-text available
The Marine and Coastal Access Act 2009 created a new type of Marine Protected Area (MPA), called a Marine Conservation Zone (MCZ). MCZs, together with other types of existing MPAs, will deliver the Government’s aim for the formation of an ‘ecologically coherent network of well managed Marine Protected Areas’. Through stakeholder engagement and consultation the Department for Food and Rural Affairs (Defra) has developed seven design principles which are to be applied to the UK network of MPAs; o Representativity o Replication o Viability o Adequacy o Connectivity o Protection o Best available evidence The objective of this study is to address the design principle of viability through the assessment of 37 species and 25 habitats which are likely to be protected by the MPA network (known as features of conservation importance – FOCI). A viable MPA has been defined within the scope of this study as being an area large enough to encompass most naturally occurring ecological processes and the home ranges of the species or groups of species characteristic of habitat communities which are the target for protection. The specific objectives of this viability assessment were to review existing literature to identify adult home ranges for species of conservation importance and to identify the minimum site area required for each habitat of conservation importance. This review focused on published peer reviewed journal articles but where gaps exist, was supplemented with data and reports produced by Marine Ecological Surveys Ltd as well as other grey literature. As most species in this review are sessile or sedentary the reviews consider several factors other than home range, important to the ecology, and hence viability of species and habitats.
... Based on the number and frequency, the dominant preys of H. guttulatus in the Aegean are Decapod crustacean larvae, Mysidaceae and Amphipoda and unidentified prey. These results are consistent with previously published data (Kitsos et al., 2008). ...
Article
The long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) is a representative species of the Romanian coast, due to its charismatic appearance and extraordinary biology. Although it is not a commercial fish in Romania, it is subjected to harvesting to be sold as curio or for the aquarium business, and many times is by-caught in trawl or pound net fishery. The current research aimed at the examination of the gut content of wild seahorse specimens, in order to determine the prey preferences of the species along the Romanian Black Sea coast. In the wild, large prey items (Amphipoda, Balanus larvae) were identified as the preferred prey of adult specimens, indicating that size and availability are important factors in prey selection. Adult seahorses appear to prefer larger prey both in wild and controlled environments, as previous research has indicated.
... The short-snouted seahorse (H. hippocampus) inhabits the coastal areas in the north-eastern Atlantic Ocean, the Mediterranean Sea and the central North Sea (Curtis et al. 2017;Franco et al. 2006;Kitsos et al. 2008;Lourie et al. 1999;Otero-Ferrer et al. 2015;Valladares et al. 2014). This species inhabits small home ranges at depths of one to 55 m, with occasional seasonal migration to deeper waters (Woodall et al. 2018). ...
Article
Full-text available
Photo-identification has been proven to be a successful individual recognition tool in seahorse species (e.g., long-snout seahorse Hippocampus reidi (Ginsburg, 1933) and long-snouted seahorse Hippocam-pus guttulatus (Cuvier, 1829)). Its use was deemed valuable for the assessment of wild populations and to understand variations in abundance over time when capture-recapture methods are needed. In this study, a computer software with a pattern recognition algorithm (I3S® Contour 3.0) was used for individual identification of short-snouted seahorses Hippocampus hippo-campus (Linnaeus 1758) in the laboratory. Using this methodology, differences in the shape of each individ-ual's coronet were tested as a unique and distinguishable characteristic. Two different contours were used as reference and tested to assess the effectiveness of this method in individual identification. A total of 94 captive-bred H. hippocampus, 45 adults (> 1 year old) and 49 young adults (4 months old), were tested. Positive matches were obtained in 55.1 % of the young adults and 84.4 % of the adults using contour 1; and in 77.6 % and 97.8 % for young adults and adults, respectively , using contour 2. All unmatched photos were later successfully matched by visual comparison, using additional traits (e.g., spot patterns) and gender. This methodology yielded very promising results and could be further used in wild individuals to allow population size estimates.
... onfish consists also of various benthic invertebrates, mainly crustaceans, and teleosts. the study of fish diet is a useful approach for understanding some aspects of their biology and ecology, towards a more sustainable management of their stocks and the development of conservation measures (Kitsos et al., 2008). Moreover, information on diet is useful for developing trophic models as a tool of understanding the complexity of coastal ecosystems (Lopez-Peralta and arcila, 2002;Stergiou and Karpouzi, 2002). ...
... In the past decades, severe decline of many seahorse populations led to the inclusion of all seahorse species, including the longsnouted seahorse Hippocampus guttulatus, on the International Union for Conservation of Nature (IUCN) [15] Red List of Threatened Species and Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) [16]. By employing morphological examination of gut or stomach contents, stomach flushing or by biochemical means, studies on their diet have shown that seahorses feed mainly on small-sized crustaceans, such as Amphipoda, Decapoda and Anomura [17] [18] [19] [20]. Recent study based on morphological examination of stomach contents revealed the presence of only a few soft-bodied prey items [17]. ...
... In the annual samples, stomach fullness was determined visually according to (30) using a scale ranging from 0 to 100% and noted as empty (0%), moderately full (25%), half full (50%), quite full (75%) and very full (100%). One-way analysis of similarity (ANOSIM) (31) was used to determine the differences between seasons in the structure of the stomach contents. ...
Article
Full-text available
The diet of the red mullet Mullus barbatus was studied in the southeast Black Sea region of Turkey during the autumn, winter, summer and spring. In one year, the stomach contents of 760 individuals of M. barbatus, a confirmed omnivorous fish species, were examined (April 2017􀂱March 2018), in addition to those of 180 additional individuals examined within a 24-h period (28 April 2018). Among the 14 prey groups identified in the stomachs of red mullet, the predominant one was Bivalvia, followed by Nematoda, Polychaeta, Brachyura and Cumacea. Data analysis revealed significant differences in prey species composition between seasons (ANOSIM, R = 0.089, p < 0.001). Moreover, the prey groups that constituted the majority of the diet changed significantly with a season. SIMPER analysis revealed that the prey item contributing the most to the differences between seasons was Bivalvia. Microplastic was also found in the samples. Analysis of the daily rhythm diet variation in stomach contents allowed the identification of 8 prey groups, namely Bivalvia, Amphipoda and Cumacea. In 24-hour examinations, feeding began in the first hours of the day, then showed an increase in the following hours and decreased after the evening. The results of this study could be used to describe the diversity of prey species and intraspecific food competition in the Black Sea.
... Normalmente, este tipo de estudios se realizan determinando el contenido del intestino, lo que requiere el sacrificio del animal y la destrucción de las muestras (Kendrick y Hyndes, 2005;Kitsos et al., 2008;Castro et al., 2008). ...
Research
Full-text available
Syngnathids are a vulnerable fish family due to anthropogenic pressures and their close relationship with the algae comunities where they live. In this study, biological and trophic characteristics of syngnathid fish populations associated with the algae communities of the Cíes Islands Archipelago (Maritime-Terrestrial National Park of the Atlantic Islands of Galicia) were analysed in three different areas under study, in spring, summer and autumn of 2018. The presence, abundance, size, weight and sexual maturity of the two species of syngnathids captured in the samplings were analyzed, the pipefish: Syngnathus acus and Entelurus aequoreous. The 15N and 13C isotopic profiles of the different taxonomic groups of epifauna and syngnatids were also analyzed. The annual monitoring revealed the existence of a relatively abundant population of large S. acus, while E. aequoreous showed low abundances and a reduced distribution, appearing exclusively in only one of the study areas (selective habitat), the same area where the highest abundances of S. acus were found. The abundance of both species decreased considerably in autumn. The analysis of stable isotopes allowed to establish the trophic structure of the habitat and identify the trophic level (NT) of the syngnathids. The results confirmed that the two species of syngnathids are primary carnivores with a similar diet and trophic position (NT = 3.61 for E. aequoreous and 3.76 for S. acus) in the three zones under study, although with seasonal variations. The present study provides interesting information on the ecology of syngnathid populations with the aim of being able to carry out future protection and conservation measures in the Atlantic Islands National Park.
... Two main obstacles identified in rearing protocols are (a) the high mortality rates during the first stages of development (0-20 days after birth), and (b) the lack of adequate and economically sustainable food sources with nutritional profiles able to meet seahorse requirements (Alexandre, 2010). In the wild, seahorses have a varied diet of live prey (e.g., small crustaceans, invertebrates and fish larvae) Kitsos, Tzomos, Anagnostopoulou, & Koukouras, 2008), which are captured by means of a 'sit and wait' foraging behaviour (James & Heck, 1994). ...
Article
This study assessed the effect of starvation on survival and nutritional status of newborn juveniles H. erectus (<10 days) to optimize rearing protocols, thereby helping to reduce wildlife exploitation. Maximum starvation time (MST) was estimated through the survival of juveniles continuously starved from birth. Resistance to starvation and the effect of food re‐introduction after 1, 2, 4 and 6 days of starvation on survival and metabolite concentrations (total proteins, total lipids, acylglycerides, cholesterol, glucose) were also determined. Survival amongst continuously starved animals decreased from 6.6 ± 0.5 to 0% from days 9 to 10 of starvation. Seahorses under different starvation–refeeding treatments all had 100% survival up to day 5 of experiments. After 10 days, however, a 4‐day starvation period followed by refeeding showed negative effects with <50% survival. During continuous starvation, lipids were the first energy reserve used to maintain basal metabolism, followed by proteins. Except for cholesterol, all metabolite concentrations differed between continuous starvations and feeding. Despite high seahorse survival after 5 days in the absence of food, the recovery of the metabolic status is possible after a starvation period of no more than 2 days, since irreversible physiological changes compromising the ultimate survival of the organisms take place after this time.
... They also have the capability of moving their eyes independently and of camouflaging well in their habitat. Generally, pipefishes feed on microcrustaceans such as copepods, amphipods, isopods, mysids, and cumaceans (Ryer and Orth 1987, Franzoi et al. 1993, Kitsos et al. 2008). ...
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The occurrence of the pink pipefish, Bryx analicarens (Duncker, 1915), is reported for the first time from Indian waters. The geographical distribution of the species extends from east Africa, the Persian Gulf and the Gulf of Oman to Pakistan and now to the west coast of India. Although a total of 32 pipefish species have hitherto been reported from India, the presently reported finding of B. analicarens constitutes the first record of the genus from the country. Morphometric characters, like the absence of the anal fin, the number of trunk rings (15) and tails rings (34), and dorsal fin rays (25) distinguish the species from other species in the region. Bryx analicarens differs from its congeners by having alternately arranged irregular brownish and white bands along the snout. The presently reported study also emphasizes the need for a detailed study of syngnathid biodiversity and a stock assessment of the coral reef ecosystems of the Gulf of Kachchh Marine National Park and Sanctuary for developing conservation strategies.
... Visual estimates of stomach fullness were made according to Kitsos et al. (2008) and were categorized as empty (0%), moderately full (25%), half full (50%), quite full (75%) and very full (100%). Furthermore, the degree of stomach fullness of S. porcus was also determined using the stomach content index (Battaglia et al., 2016): ...
Article
Black scorpion fish ( Scorpaena porcus ) is an important species for both artisanal and industrial fisheries in the Turkish Black Sea, with 306 tonnes landed in 2017. The diet composition of this species was investigated through the examination of their stomach contents. A total of 621 S. porcus (ranging from 12.79–765.5 g) were caught by trammel net in the south-eastern Black Sea (Turkish waters) from December 2015 to November 2016. The importance of prey items in the diet of S. porcus was assessed using the Index of Relative Importance (%IRI). Overall, the dominant species was the isopod Idotea balthica (52.8%IRI) followed by decapods (38.5%IRI) and teleosts (8.7%IRI). Seasonal variations in the diets were observed, with isopods predominant in autumn (>85%IRI), teleosts in winter (>77%IRI) and decapod crustaceans (>78%IRI) in spring and summer. The modified Costello's graphical analysis evinced a specialist feeding strategy for S. porcus during winter, spring and autumn while a shift to generalistic feeding strategy was exhibited in summer by a limited number of S. porcus individuals.
... The results of the present work provide information about the distribution of the spotted goatfish and its trophic relations among different habitats and locations. Dietary analysis is a particularly important tool for comprehending aspects of biology and ecology, especially when allied with spatial marine planning aimed at sustainable management of fishing stocks and the development of conservation measures (La Mesa et al. 2007, Kitsos et al. 2008. In fact, our results endorse Eduardo et al. (2018), who identified several potential areas for implementation of MPAs, contributing to future management and conservation measures for this species. ...
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This study provides information about the feeding habits, population aspects and spatial distribution of the spot­ted goatfish, Pseudupeneus maculatus, along the coast of the tropical Brazilian continental shelf. Distribution patterns are described using length frequencies and catch rates. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N), along with stomach contents, were analysed to determine the diet of the spotted goatfish. Multivariate analysis and numerical indicators of the diet, such as numerical frequency, frequency of occurrence and weight percentage, were computed to evaluate the diet composition. The mean trophic position was defined using both stable isotope ratios and stomach content analysis. The length at first maturity for the species was determined as 13.7 cm. A slight pattern in size distribution was observed, with mean size increasing with depth along the shelf. The diet was mainly composed of crustaceans, teleosts and Polychaeta. No clear dietary difference was found between habitat types, water depth or latitude. Both trophic positions estimated by stable isotopes and stomach contents analysis ranged between levels 3 and 4. P. Maculatus was found to be feeding on many rare and infrequent prey items, classifying it as a generalist zoobenthivorous predator, probably due to its efficient search strategy.
... Despite the extended geographical distribution of both species, there are only a few inshore locations where seahorse abundance, distribution and habitat use have been studied within the Mediterranean Sea (Ape et al., 2019;Gristina et al., 2015;Louisy, 2011). To the authors' knowledge, ecological data have been rare in Greek waters and especially in the Aegean Sea focusing on wild seahorse population structure (Kitsos et al., 2008;Woodall et al., 2018), including ichthyofaunal assessments (Koutrakis et al., 2005;Lamprakis et al., 2008). ...
Article
The present study was carried out in the marine area of Stratoni, Greece, where two seahorse species are present (Hippocampus hippocampus and H. guttulatus). Two surveys were conducted (September 2016, May 2019) to gather information regarding seahorse species' abundance, distribution and habitat characteristics. Four different seahorse natural and artificial habitat types were identified. Results revealed that the abundance of H. hippocampus was relatively high, especially at sites with artificial structures, while the presence of H. guttulatus was rare. Data collected can provide baseline information for future population assessments.
... Based on the number and frequency, the dominant preys of H. guttulatus in the Aegean are Decapod crustacean larvae, Mysidaceae and Amphipoda and unidentified prey. These results are consistent with previously published data (Kitsos et al., 2008). ...
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The long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) is a representative species of the Romanian coast, due to its charismatic appearance and extraordinary biology. Although it is not a commercial fish in Romania, it is subjected to harvesting to be sold as curio or for the aquarium business, and many times is by-caught in trawl or pound net fishery. The current research aimed at the examination of the gut content of wild seahorse specimens, in order to determine the prey preferences of the species along the Romanian Black Sea coast. In the wild, large prey items (Amphipoda, Balanus larvae) were identified as the preferred prey of adult specimens, indicating that size and availability are important factors in prey selection. Adult seahorses appear to prefer larger prey both in wild and controlled environments, as previous research has indicated.
... Similarly, females of several pipefish species eat more and larger prey than males (e.g. Svensson 1988;Steffe et al. 1989;Teixeira and Musick 1995;Lyons and Dunne 2004;Garcia et al. 2005;Kitsos et al. 2008;Manning et al. 2019). Assuming that H. subelongatus females also need more food and that a large home range provides access to more food, we predict females to have larger home range sizes than males. ...
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Genetic monogamy is the rule for many species of seahorse, including the West Australian seahorse Hippocampus subelongatus . In this paper, we revisit mark-recapture and genetic data of H. subelongatus , allowing a detailed characterization of movement distances, home range sizes and home range overlaps for each individual of known sex, paired status (paired or unpaired) and body size. As predicted, we find that females have larger home ranges and move greater distances compared to males. We also confirm our prediction that the home ranges of pair-bonded individuals (members of a pair known to reproduce together) overlap more on average than home ranges of randomly chosen individuals of the opposite or same sex. Both sexes, regardless of paired status, had home ranges that overlapped with, on average, 6–10 opposite-sex individuals. The average overlap area among female home ranges was significantly larger than the overlap among male home ranges, probably reflecting females having larger home ranges combined with a female biased adult sex ratio. Despite a prediction that unpaired individuals would need to move around to find a mate, we find no evidence that unpaired members of either sex moved more than paired individuals of the same sex. We also find no effect of body size on home range size, distance moved or number of other individuals with which a home range overlapped. These patterns of movement and overlap in home ranges among individuals of both sexes suggest that low mate availability is not a likely explanation for the maintenance of monogamy in the West Australian seahorse.
... Seahorses that are kept in optimal conditions will spawn naturally [43]. The diet of seahorses in the wild predominantly consists of small pelagic crustaceans, such as amphipods, copepods, and mysids [190][191][192][193][194][195][196], but nematodes are also important prey, depending on the habitat [197,198]. Prey shape and size are very much determined by the form of the seahorse head, in particular the long and tubular snout, and by their special feeding behavior, including suction and pivot feeding [199][200][201][202][203][204][205]. ...
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Seahorses (Hippocampus spp.) are threatened as a result of habitat degradation and overfishing. They have commercial value as traditional medicine, curio objects, and pets in the aquarium industry. There are 48 valid species, 27 of which are represented in the international aquarium trade. Most species in the aquarium industry are relatively large and were described early in the history of seahorse taxonomy. In 2002, seahorses became the first marine fishes for which the international trade became regulated by CITES (Convention for the International Trade in Endangered Species of Wild Fauna and Flora), with implementation in 2004. Since then, aquaculture has been developed to improve the sustainability of the seahorse trade. This review provides analyses of the roles of wild-caught and cultured individuals in the international aquarium trade of various Hippocampus species for the period 1997–2018. For all species, trade numbers declined after 2011. The proportion of cultured seahorses in the aquarium trade increased rapidly after their listing in CITES, although the industry is still struggling to produce large numbers of young in a cost-effective way, and its economic viability is technically challenging in terms of diet and disease. Whether seahorse aquaculture can benefit wild populations will largely depend on its capacity to provide an alternative livelihood for subsistence fishers in the source countries. For most species, CITES trade records of live animals in the aquarium industry started a few years earlier than those of dead bodies in the traditional medicine trade, despite the latter being 15 times higher in number. The use of DNA analysis in the species identification of seahorses has predominantly been applied to animals in the traditional medicine market, but not to the aquarium trade. Genetic tools have already been used in the description of new species and will also help to discover new species and in various other kinds of applications.
... The natural diet of most seahorse species is dominated by small crustaceans, primarily copepods, mysid shrimps, decapods and amphipods (Manning, Foster & Vincent, 2019 (Teixeira, Musick & Musik, 2001;Kendrick & Hyndes, 2005;Kitsos et al., 2008;Storero & González, 2008). Adult H. erectus, the lined seahorse, feed almost exclusively on amphipods (mainly Gammarus muconathus), whereas juveniles on both amphipods (mainly Ampithoe longimana) and copepods (Teixeira, Musick & Musik, 2001). ...
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Finding new alternatives to traditional live preys such as Artemia and rotifers, which do not always promote optimal fish growth and survival, is required for the successful aquaculture of highly specialized predatory species, including seahorses. The present study assessed the nutritional value of an interesting marine amphipod ( Parhyale hawaiensis ), and evaluates through a feeding trial its potential use as a natural prey for 10-months lined seahorse, Hippocampus erectus . P. hawaiensis showed high levels of valuable lipids (20.4–26.7% on dry matter basis) and polyunsaturated fatty acids (PUFAs) ( 26.4–41% of total FAs), including the long-chain PUFAs (LC-PUFAs) arachidonic acid (ARA) (2.9–7.7%), eicosapentaenoic acid (EPA) (4.3–6.5%) and docosahexaenoic acid (DHA) (2.1–6.2%). A comparison between wild-captured and cultured amphipods revealed a significant improvement of the amphipod FA profile in terms of DHA%, total omega-3 (n3) FAs and n3/n6 ratio when employing both a conventional amphipod culture based on a commercial shrimp diet, and, to a lesser extent, a large (3,500 L) biofloc system. Seahorses fed with frozen/wild amphipods, either singly or in combination with Artemia enriched with Super Selco® (INVE Aquaculture, Belgium) for 57 days, substantially improved seahorse growth and FA profiles in terms of ARA, EPA and DHA%, including indices associated to marine sources, such as Σn3 and n3/n6, compared to a diet based solely on enriched Artemia . These results support the use of marine amphipods as an alternative food organism for juvenile H. erectus and suggest a potential use for general marine aquaculture.
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Functional characterization of the fish ecophases. (PDF)
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Syngnathids are vulnerable fishes closely associated with seaweeds and seagrass, which provide shelter and food resources. Even though most syngnathids commonly feed on small crustaceans, the feeding regimes may differ depending on the species and prey availability. This is the first monitoring study to explain syngnathid abundances and dietary regimes within macroalgal beds in Cíes Archipelago (Atlantic Islands Marine National Park, North West Iberian Peninsula). We sampled the epifaunal assemblages in seaweed communities dominated by the canopy-forming macroalgae Gongolaria baccata and Codium spp. seasonally during 2 years. The epifaunal structure was mostly represented by harpacticoid copepods, amphipods (especially gammarids) and gastropods. Epifauna exhibited low plant-host specificity and a higher dominance of amphipods on the more structurally complex macroalgae G. baccata. The epifaunal assemblages and syngnathid specimens were assessed for trophic structure using stable isotopes (δ ¹³ C and δ ¹⁵ N). The three syngnathids ( Hippocampus guttulatus , Syngnathus acus , and Entelurus aequoreus ) inhabiting Cíes Archipelago were sympatric. They occupied highly similar trophic positions (TPs), but differed in niche size, in such a way that the snake pipefish E. aequoreus would likely feed on smaller prey. The assessment of the feeding regime in the dominant great pipefish S. acus revealed that amphipods mostly contributed to bulk diet, followed by isopods, carideans, and copepods, whereas mysidaceans were not highly consumed. Seasonal changes in both epifaunal structure and syngnathids abundance confirmed that syngnathids are seasonal residents in Cíes Archipelago, migrating to other areas in autumn when the seaweed cover is drastically reduced and the epifaunal structure modified. This study showed the importance of Gongolaria assemblages in Cíes Archipelago, providing rich dietary sources and potentially contributing to higher abundances and diversity of syngnathids. Ongoing cover reduction in Gongolaria assemblages in certain regions (e.g., Mediterranean) should be considered a potential ecological concern for syngnathids and accompanying fauna, requiring further investigations.
Article
To improve the understanding of the life history and ecology of one of Europe's most elusive fishes, the short-snouted seahorse Hippocampus hippocampus, data from wild populations in a shallow coastal lagoon in southern Portugal were analysed. The data were collected from 17 tagged seahorses on a focal-study grid as well as from >350 seahorses encountered during underwater visual surveys and a fishery-independent study using beach seines. These populations of settled juveniles and adults had a mean population density of 0·009 m−2. During the study period (2000–2004), reproduction peaked in July and August. Juveniles recruited to the lagoon at c. 66 mm standard length (LS) and 0·5 years of age and established small home ranges (0·8 to 18·2 m2). First reproduction was estimated at 100 mm and 1 year of age. Based on a fitted von Bertalanffy model, H. hippocampus grew quickly (growth coefficient K = 0·93) to a maximum theoretical size L∞ = 150 mm and have a maximum lifespan of c. 3·2 years. Courtship behaviours were consistent with the maintenance of pair bonds and males brooded multiple batches of young per year. Estimated annual reproductive output averaged 871 young (±632). Together these analyses provide the first life-history parameters for this species and indicate that H. hippocampus bears characteristics of opportunist and intermediate strategists. Such populations are predicted to exhibit large fluctuations in abundance, making them vulnerable to extended periods of poor recruitment.
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While there have been many anecdotal reports of sounds produced by Hippocampus seahorses, little is known about the mechanisms of sound production. We investigated clicking sounds produced during feeding strikes in H. zosterae and H. erectus. Descriptions of head morphology support the idea that feeding clicks may represent stridulatory sounds produced by a bony articulation between the supraoccipital ridge of the neurocranium and the grooved anterior margin of the coronet. Analysis of high-speed video and synchronous sound recordings of H. erectus indicate that the feeding click begins within 1-2 msec of the onset of the rapid feeding strike (4 msec mean duration). Surgical manipulations of the supraoccipital-coronet articulation resulted in a decreased proportion of feeding strikes that produced clicks. This study provides several lines of evidence in support of the hypothesis that feeding clicks in Hippocampus seahorses are stridulatory in origin and are produced by the supraoccipital-coronet articulation. Our results are not consistent with previous suggestions that sounds may be produced by cavitation due to rapid pressure changes within the buccal cavity during the feeding strike.
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We present estimates of local population abundance, distribution and habitat preference for 2 European seahorse species, Hippocampus guttulatus and H. hippocampus. We predicted that these sympatric species would partition their habitat into 2 broadly defined habitat types: complex vegetated habitats and sparsely vegetated sand flats. We sampled populations using underwater visual census techniques over landscape (100s to 1000s m) and microhabitat scales (<1 m). Over landscape scales, we estimated abundance and quantified habitat associations using generalized linear models. Over microhabitat scales, we tested for holdfast (attachment site) preferences using selection indices. Both species were patchy in distribution, but H. guttulatus mean density (0.073 ind. m-2) was one order of magnitude greater than that of H. hippocampus (0.007 ind. m-2). At a landscape scale, H. guttulatus abundance was positively correlated with an index of habitat complexity, the percentage of substrate covered by flora and sessile fauna. Conversely, H. hippocampus used more open and less speciose habitats that were subjected to greater oceanic influences. At microhabitat scales, both species significantly preferred grasping holdfasts over barren surfaces, but the species differed in holdfast preferences: H. guttulatus grasped all prospective holdfast types with equal probability while H. hippocampus significantly avoided both fauna and flora that formed large colonies or tracts of dense vegetation. Patterns in habitat use were consistent with differences in morphology and foraging strategy. Despite similar life histories, these sympatric species may respond differently to disturbances that modify habitat structure and complexity over landscape or microhabitat scales.
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This investigation examined the diet of adult wild seahorses, Hippocampus abdominalis Leeson 1827, from Wellington Harbour, New Zealand. Diet of seahorses (n = 59) collected from shallow subtidal macroalgal stands consisted largely of crustaceans, in particular amphipods (e.g., caprellid and ischyrocerid amphipods), caridean shrimp (i.e., Hippolyte bifidirostris), and peracarids (i.e., the mysid Tenagomysis similis). There were no differences in diet between male and female seahorses. Smaller seahorses consumed a greater amount of crustaceans than larger seahorses, as a result of the greater proportion of amphipods in their gut contents. There were some seasonal differences in diet, with amphipod consumption peaking in spring and summer, and decapod consumption lowest in autumn.
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1. A study was set up in the Port-Cros National Park in order to determine the effects of boat anchoring on Posidonia oceanica seagrass beds.2. Experiments on the effects of anchors on the seagrass meadows revealed that, on average, 34 shoots were destroyed during an anchoring cycle (lock-in and retrieval), especially when the seagrass mat compactness is weak and the extent of rhizome baring is high.3. Five parameters of the Posidonia oceanica beds (meadow cover, shoot density, extent of rhizome baring, proportion of plagiotropic rhizomes, degree of meadow fragmentation) were considered and it was shown that the extent of rhizome baring was not correlated with anchoring pressure. Meadow cover and mean shoot density were positively correlated with high anchoring pressure.4. The proportion of plagiotropic (i.e. horizontally growing) rhizomes and the degree of meadow fragmentation were positively correlated with moderate anchoring pressure. Copyright © 1999 John Wiley & Sons, Ltd.
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In the early 1980s, a strategy for graphical representation of multivariate (multi-species) abundance data was introduced into marine ecology by, among others, Field, et al. (1982). A decade on, it is instructive to: (i) identify which elements of this often-quoted strategy have proved most useful in practical assessment of community change resulting from pollution impact; and (ii) ask to what extent evolution of techniques in the intervening years has added self-consistency and comprehensiveness to the approach. The pivotal concept has proved to be that of a biologically-relevant definition of similarity of two samples, and its utilization mainly in simple rank form, for example ‘sample A is more similar to sample B than it is to sample C’. Statistical assumptions about the data are thus minimized and the resulting non-parametric techniques will be of very general applicability. From such a starting point, a unified framework needs to encompass: (i) the display of community patterns through clustering and ordination of samples; (ii) identification of species principally responsible for determining sample groupings; (iii) statistical tests for differences in space and time (multivariate analogues of analysis of variance, based on rank similarities); and (iv) the linking of community differences to patterns in the physical and chemical environment (the latter also dictated by rank similarities between samples). Techniques are described that bring such a framework into place, and areas in which problems remain are identified. Accumulated practical experience with these methods is discussed, in particular applications to marine benthos, and it is concluded that they have much to offer practitioners of environmental impact studies on communities.
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The reproductive and feeding biology of the lined seahorse, Hippocampus erectus, was studied in Chesapeake Bay. Seahorses are monogamous, and males incubate the eggs received from females in a closed brood pouch (= marsupium). Females do not play any parental care after mating. Total sex ratio and the operational sex ratio was strongly skewed toward females. Males and females had similar number of eggs/embryos and hydrated oocytes, respectively. The number of eggs/embryos found in the male brood pouch varied from 97 to 1,552 (fish from 80 to 126 mm TL), whereas the number of hydrated oocytes in female varied from 90 to 1,313 (fish from 60 to 123 mm TL). Both, the number of eggs/embryos and hydrated oocytes were better linearly correlated to total weight than to total length. The small snout and mouth size limits the feeding of the lined seahorse to small prey size. Amphypods were the predominant food items found in the guts, especially Ampithoe longimana, Gammarus mucronatus, and Caprella penantis. The lined seahorse is not abundant in Chesapeake Bay, but keeps a breeding population which is probably brought inside the bay by currents on drifting vegetation. Chances to find a partner may be difficult because of its low abundance, due to turbid waters, and its sedentary behavior.
Article
Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.
Article
The life history of the long‐snouted seahorse Hippocampus guttulatus was characterized using mark‐recapture data collected within a focal study site and catch data from 53 additional sites in the Ria Formosa coastal lagoon, southern Portugal. Population structure in benthic habitats was characterized by high local densities (0·3–1·5 m−2), equal sex ratios and few juveniles H. guttulatus maintained small (19·9 ± 12·4 m2), strongly overlapping home ranges during multiple reproductive seasons. Recruited (benthic) juveniles exhibited significantly lower site fidelity than adults. A Ford‐Walford plot of standard length (LS) at time t against LS measured during the previous year from tagged juveniles and adults led to estimates of the von Bertalanffy parameters K = 0·571 and L∞ = 197·6 mm. The growth rate of planktonic juveniles (inferred from previous studies), was greater than predicted by the von Bertalanffy model, providing evidence of an ontogenetic shift in growth trajectory. The instantaneous rate of natural mortality, M, ranged from 1·13 to 1·22 year−1(annual survival rate = 29·4–32·2%). Sexes did not differ in movement, growth or survival patterns. On average, H. guttulatus measured 12·2 ± 0·8 mm at birth. Planktonic juveniles recruited to vegetated habitat at 96·0 ± 8·0 mm (0·25 years), had mature brood pouches (males only) at 109·4 mm (0·49 years), began maintaining home ranges and reproducing at 125–129 mm (0·85–0·94 years), and lived for 4·3–5·5 years. Early age at maturity, rapid growth rates, and short generation times suggested that H. guttulatus may recover rapidly when direct (e.g. exploitation) and indirect (e.g. by‐catch and habitat damage) effects of disturbance cease, but may be vulnerable to extended periods of poor recruitment.
Article
Feeding habits of the Pacific pomfret Brama japonica, ranging from 30 to 40 cm in standard length, were quantitatively evaluated using the index of relative importance and were compared between the transitional domain and subarctic region in the central North Pacific. In the transitional domain (between the subarctic boundary and the subarctic front), this species fed mainly on subarctic and transitional‐water gonatid squids such as Berryteuthis anonychus, Gonatus middendorffi and Gonatopsis borealis, the transitional‐water squid Onychoteuthis borealijaponica, and a subtropical and transitional‐water amphipod, Phronima sedentaria. These prey items accounted for 52·8% by wet mass of total stomach contents. In the subarctic region (north of the subarctic front), Pacific pomfrets preyed primarily on subarctic and transitional‐water squids, such as B. anonychus and G. middendorffi, and secondarily on subarctic amphipods such as Hyperia medusarum and Hyperia glaba. These four prey items comprised 71·6% by mass of total stomach contents. Major transitional domain prey items, such as G. borealis, O. borealijaponica and P. sedentaria, were almost non‐existent in stomachs of fish from the subarctic region. The mean wet stomach content mass expressed as a percentage of body mass was significantly higher in the subarctic region (2·35%) than in the transitional domain (0·75%), suggesting that, for this fish, prey items are more readily available in the subarctic region during summer and their northward migration is a feeding migration. Feeding strategy of the Pacific pomfret was discussed in relation to their seasonal south‐north migration.
Article
Merits of the points and occurrence methods for measuring the relative importance of types of food eaten by four species of portunid crabs (Portunus pelagicus (Linnaeus, 1766), Thalamita crenata H. Milne Edwards 1834, T. danae Stimpson 1858, and T. sima H. Milne Edwards 1834) have been compared. Both methods describe different aspects of the relative importance of food items and the scores given by each were highly correlated for most types of food. The points method is unsuitable for foods which consist of a high proportion of soft tissue whereas the occurrence method is appropriate for most foods. Fewer types of food were found in nearly empty gastric mills than in full mills. A sample size of approximately 30 gastric mills, each at least 50% full, was determined empirically to be adequate for a description of natural diet.
Article
1. The effect of habitat fragmentation was investigated in two adjacent, yet separate, intertidal Zostera marina beds in the Salcombe Estuary, Devon, UK. The seagrass bed on the west bank comprised a continuous meadow of ca. 2.3 ha, whilst the bed on the east bank of the estuary was fragmented into patches of 6–9 m2.2. Three 10 cm diameter core samples for infaunal macroinvertebrates were taken from three stations within each bed. No significant difference was found in univariate community parameters between beds, or in measured seagrass parameters. However, multivariate analysis revealed a significant difference in community composition, due mainly to small changes in species abundance rather than differences in the species present.3. The species contributing most to the dissimilarity between the two communities were polychaetes generally associated with unvegetated habitats (e.g. Magelona mirabilis) and found to be more common in the fragmented bed.4. A significant difference in median grain size and sorting coefficient was recorded between the two beds, and median grain size was found to be the variable best explaining multivariate community patterns.5. The results of the study provide evidence for the effects of habitat fragmentation on the communities associated with seagrass beds, habitats which are of high conservation importance. As the infaunal community is perhaps intuitively the component least likely to be affected by fragmentation at the scale observed, the significant difference in community composition recorded has consequences for more sensitive and high-profile parts of the biota (e.g. fish), and thus for the conservation of seagrass habitats and their associated communities. Copyright © 1999 John Wiley & Sons, Ltd.
Article
Pelagic North Sea whiting Merlangius merlangus preyed upon (pelagic) sprat and sandeel, while demersal whiting preyed upon (demersal) Norway pout and herring. Values of diet breadth were low for both feeding groups using Levin's index. Diet overlaps within layers were low (D <0·25), while the between layer food overlap was moderate (D=0·25–0·74) to high (D >0·74) using Schoener's index. Selection of prey was density dependent. However, prey size also played an important role. The diet of whiting shifted from amphipods and mysids to fish with increasing predator length, and the length of prey consumed increased significantly with length of whiting. The fact that the stomach contents differed between the feeding groups demonstrates the need for a sampling design that includes both pelagic and demersal habitats when trying to quantify the diet of whiting.
Article
Possible changes in diet and trophic levels in relation to size of Mediterranean bluefin tuna, Thunnus thynnus, were investigated using labelled carbon (δ13C) and nitrogen (δ15N) stable isotopes. Samples were obtained from two locations in the southern Tyrrhenian Sea (Western Mediterranean Sea) in May and October 2004. The δ13C and δ15N analyses revealed at least three significant isotopic groups [small juveniles (0.7–2.2 kg), sub-adults (15–50 kg) and adults (70 to 225 kg)]. δ13C was negatively dependent on weight, while δ15N was positively dependent on weight [TW = 8.2 (±0.16) + 0.03 (± 0.0) *δ15N (n = 49; r = 0.91; P < 0.001)]. Different prey contribution to the diet was highlighted for each class. The diet of juveniles comprised zooplankton, small pelagic fish and some coastal fish; sub-adults relied on medium pelagic fish, shrimps and cephalopods, and adults relied mainly on cephalopods and larger fish. The trophic level (TL) of tunas belonging to each size class was closely correlated to weight, starting from ca 3.0 TL for Group I and reaching 4.4–4.8 TL for the giants. Bluefin tuna, from small juveniles to giants, showed a shift in feeding preferences due to different use of habitats and food items as a function of the life stage.
Article
We present the first synthesis of the life history and ecology of seahorses, compare relationships for seahorses with other marine teleosts and identify research needs. Seahorses occurred primarily amidst temperate seagrasses and tropical coral reefs. Population densities were generally low, ranging from 0 to 0·51 individuals m−2, but reached 10 m−2 in some patches. Inferred life spans ranged from 1 to 5 years. Seahorses consumed live prey and possibly changed diet as they grew. Growth rates are poorly investigated to date. Reproduction and mating systems are the best-studied aspects of seahorse ecology. The relationship between size at first maturity and maximum size in seahorses conformed to that for other marine teleosts. All seahorse species were monogamous within a cycle, but some were polygamous across cycles. Direct transfer of clutches to the brood pouch of the male fish made it difficult to measure clutch size in live seahorses. After brooding, males released from c. 5 to 2000 young, depending on species and adult size. Newborn young measured from 2 to 20 mm in length, which was a narrower size range than the 17-fold difference that occurred in adult size. Newborn body size had no relationship to adult size. Both eggs and young were larger than expected among marine teleosts, even when considering only those with parental care, but brood size at release was lower than expected, perhaps because the young were more developed. The size of adults, eggs and young increased with increasing latitude, although brood size did not. Considerable research is needed to advance seahorse conservation and management, including (a) fisheries-dependent and fisheries-independent abundance estimates, (b) age- or stage-based natural and fishing mortalities, (c) growth rates and age at first maturity, and (d) intrinsic rates of increase and age- or size-specific reproductive output. Current data confirm that seahorses are likely to be vulnerable to high levels of exploitation.
Article
In order to assess diet composition and niche breadth of this species, we analysed the stomach content of 182 specimens collected monthly along the eastern coast of Sicily (Central Mediterranean Sea). Overall, 50 prey taxa belonging to five major groups (algae, gastropods, crustaceans, polychaetes, fishes) were identified in 102 full stomachs. Benthic or epibenthic crustaceans, such as decapods, amphipods and isopods were the most important prey, whereas algae, gastropods, polychaetes and fishes were only occasionally ingested. In terms of composition by species, the diet of Scorpaena maderensis was characterized by a variety of rare or unimportant prey, which was consumed by few individuals only, although sometimes in large amount. As a result, S. maderensis can be considered a generalized and opportunistic feeder. The feeding intensity followed roughly a seasonal trend, with a minimum food intake in summer. The individual fish size was the most important factor affecting diet. According to the observed ontogenetic shift, small-sized individuals fed primarily on small crustaceans (i.e. amphipods and isopods), whereas large-sized specimens consumed preferably bigger and more vagile prey, such as walking and swimming decapods. No significant differences in diet were observed in relation to sex of predator and sampling season.
Article
Synopsis We examined the diets of 12 morphologically diverse syngnathid species in shallow seagrass-dominated marine waters of south-western Australia to determine whether they differed among species that varied in body form, size and snout morphology, and in particular whether species with long snouts ingested more mobile prey. Although all species consume mainly small crustaceans, the dietary compositions of these species often vary markedly. We suggest that these differences are related to factors that influence both their foraging capabilities and/or locations. Those species with long snouts (e.g. the common seadragon Phyllopteryx taeniolatus and long-snouted pipefish Vanacampus poecilolaemus) consume far more relatively mobile prey than species with short snouts. Species with short snouts (e.g. the pug-nosed pipefish Pugnaso curtirostris and Macleays crested pipefish Histiogamphelus cristatus) mainly consume slow moving prey. Spotted pipefish, Stigmatopora argus, and wide-bodied pipefish, Stigmatopora nigra, restrict their diets to planktonic copepods, probably because their small gape size limits their ability to feed on alternative larger prey. Both the short-snouted seahorse, Hippocampus breviceps, and West Australian seahorse, Hippocampus subelongatus, ingest mainly slow-moving prey, even though the latter species possesses a moderately long snout. This may reflect the fact that seahorses are weak swimmers that anchor themselves to vegetation or the substrate with a strongly prehensile tail and rarely venture into open water to pursue mobile prey. In contrast, the relatively large P. taeniolatus, which resides above, rather than within, the macrophyte canopy, consumes mysids, which aggregate in open water above the seabed. Those pipefishes with characters that imply relatively enhanced mobility, such as well developed caudal fins and non-prehensile tails, are trophically diverse, suggesting that they are able to feed either on the sediment or phytal surfaces or in the water column.
The International Trade in Seahorses
  • A C J Vincent
Vincent, A. C. J. (1996). The International Trade in Seahorses. Cambridge: TRAFFIC International.
Stomach content analysis – a review of methods and their applications doi: 10.1111/j.1095-8649. 1980.tb02775 Dominant role of exotic invertebrates, mainly Crustacea, in diets of fish in the lower Rhine River
  • E J Hyslop
  • B Kelleher
  • Van
  • G Velde
  • P Giller
  • Bij
  • A Vaate
Hyslop, E. J. (1980). Stomach content analysis – a review of methods and their applications. Journal of Fish Biology 17, 411–429. doi: 10.1111/j.1095-8649. 1980.tb02775.x Kelleher, B., Van der Velde, G., Giller, P. & Bij de Vaate, A. (2000). Dominant role of exotic invertebrates, mainly Crustacea, in diets of fish in the lower Rhine River. In The Biodiversity Crisis and Crustacea (Von Vaupel Klein, J. C. & Schram, F. R., eds), Crustacean Issues 12, 35–46.
2006 IUCN Red List of Threatened Species
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