The first known fossil record of pipehorses (Teleostei: Syngnathidae: Haliichthyinae) from the Miocene Coprolitic Horizon from the Tunjice Hills,Slovenia

The first known fossil specimens of pipehorses (Haliichthyinae) were unearthed from the Middle Miocene (Sarmatian) beds of the Coprolitic Horizon in the Tunjice Hills, Slovenia. These fossil pipehorses belong to a new genus and species Hippohaliichthys edis, which was similar to the extant species Haliichthys taeniophorus. The body morphology indicates that the described fossil pipehorses were also closely related to the pygmy pipehorse Hippotropiscis frenki and the seahorse Hippocampus sarmaticus, two taxa which were also found in the Coprolitic Horizon. The described fossil material of pipehorses indicates that seahorses evolved from a group of pipehorses that were similar in size and shape to extant and fossil pipehorses of the Haliichthyinae subfamily.     

The first known fossil record of pygmy pipehorses (Teleostei: Syngnathidae: Hippocampinae) from the Miocene Coprolitic Horizon,Tunjice Hills,Slovenia

The first known fossil record of pygmy pipehorses is described. The fossils were collected in the Middle Miocene (Sarmatian) beds of the Coprolitic Horizon in the Tunjice Hills, Slovenia. They belong to a new genus and species Hippotropiscis frenki, which was similar to the extant representatives of Acentronura, Amphelikturus, Idiotropiscis, and Kyonemichthys genera. Hippotropiscis frenki lived among seagrasses and macroalgae and probably also on a mud and silt bottom in the temperate shallow coastal waters of the western part of the Central Paratethys Sea. The high coronet on the head, the ridge system and the high angle at which the head is angled ventrad indicate that Hippotropiscis is most related to Idiotropiscis and Hippocampus (seahorses) and probably separated from the main seahorse lineage later than Idiotropiscis.     

Species identification and genetic structure of threatened seahorses in Gran Canaria Island (Spain) using mitochondrial and microsatellite markers

A non-invasive DNA analysis of seahorse populations was carried out after extensive underwater surveys in Gran Canaria Island (Spain). In this geographical area, the presence of two species, Hippocampus hippocampus and H. guttulatus, has been previously reported. Sequencing of 16S ribosomal DNA (16S rDNA) was used for specific identification of live seahorses sampled in situ, as a previous step to evaluate genetic structure based on ten microsatellite markers. Phylogenetic analyses revealed the presence of a single species, H. hippocampus, in the seahorse communities found at Gran Canaria. No evidences of H. guttulatus or interspecific hybrids were found based on 16S rDNA and microsatellite data. The nuclear markers revealed low genetic diversity and lack of population structure across populations of Gran Canaria Island, with evidence of small population sizes. This study provides critical information to support conservation strategies of Gran Canaria seahorses.     

High-throughput sequencing-based analysis of bacterial communities associated with Barbour's seahorses (Hippocampus barbouri) from Surigao del Norte,Philippines

This study identified the bacterial community composition associated with Barbour's seahorses (Hippocampus barbouri). Seahorses and samples from the surrounding environment (sediment and water) were collected from Cantiasay Island in Surigao del Norte, Philippines. Genomic DNA was isolated from these samples, and the V1–V3 region of the 16S rRNA gene was amplified and sequenced on the Illumina MiSeq platform. There were 929 803 sequence reads corresponding to 859 operational taxonomic units (OTUs), which were obtained from the six genomic libraries. The results showed that the most abundant OTUs were affiliated to the phylum Proteobacteria, particularly those belonging to the genera Shewanella, Pseudomonas, Acinetobacter and Aeromonas, which were found to be dominant in seahorse gut samples. The only exception was for the skin of male seahorses, which was dominated by members belonging to the genus Bacillus (phylum Firmicutes). These findings on bacterial community structure and composition may shed light on therapeutic claims of Barbour's seahorses and help in the conservation of this species.     

An assessment of West African seahorses in fisheries catch and trade

This study provides the first assessment of a heavily traded West African seahorse species, Hippocampus algiricus, and the first information on short‐snouted seahorse Hippocampus hippocampus biology in Africa. A total of 219 seahorses were sampled from fisher catch in Senegal and The Gambia, with estimated height at reproductive activity for H. algiricus (161 mm) larger than mean ± s.d . catch height (150 ± 31 mm). Catch composition, height at reproductive activity and potential biases in fishery retention are discussed with regard to the current Convention on International Trade of Endangered Species (CITES) guidelines.     

Non-lethal dorsal fin sampling for stable isotope analysis in seahorses

Sampling collection for stable isotope analysis has traditionally involved the sacrifice of the animal. Seahorses (Hippocampus spp.) are listed as threatened by the Convention on International Trade in Endangered Species (http://www.cites.org) and consequently lethal sampling is undesirable. We evaluated the adequacy of dorsal fin tissue of adult seahorses Hippocampus guttulatus for stable isotope analysis as an alternative to lethal tissue sampling. Three seahorse tissues (dorsal fin, muscle, and liver) were analyzed for comparisons of δ¹⁵N and δ¹³C values. Similarities found between δ¹⁵N and δ¹³C values in dorsal fin and muscle tissue of H. guttulatus suggest that both tissues are adequate for stable isotope analysis to understand feeding ecology of seahorses. However, considering the threatened status of the species, dorsal fin tissue would be recommended in adult seahorses as a non-lethal sampling. The effect of lipid extraction on carbon and nitrogen stable isotope values was also evaluated in each seahorse tissues. Significant effects of lipids extraction did only occur for δ¹³C values in muscle and liver. It was found that lipid removal was not necessary to perform SIA in dorsal fin tissues. Due to the limited availability of fin tissue obtained from fin-clipping in seahorses, the relationship between the mass/surface of dorsal fin clip and stable isotope values was analyzed. δ¹⁵N and δ¹³C values in fin samples were found to be independent of the size of fin analyzed. According to our study, the use of fin-clipping sampling, with a minimum surface analyzed of 12.74?mm², was found to be an adequate method for SIA in seahorses.     

Population characteristics of two seahorses, Hippocampus coronatus and Hippocampus mohnikei, around seagrass beds in the southern coastal waters of Korea

Population characteristics of two seahorse species, Hippocampus coronatus and Hippocampus mohnikei, in seagrass beds in the southern coastal waters of Korea were determined based on field observations. In Zostera beds in the Yeosu area, there was a mean density of 2.9 seahorses per 1,000?m² for H. coronatus and 1.4 seahorses per 1,000?m² for H. mohnikei. The greatest numbers of young individuals of both species were observed in July, with numbers decreasing through November. The male:female sex ratio was 1:1.6 for H. mohnikei and 1:1.7 for H. coronatus. Breeding males of H. coronatus and H. mohnikei were observed from July to November and from July to September, respectively. Within the study site, the populations of the two seahorse species exhibited low density and patchy distributions, with variation in temporal abundance being significantly correlated with water temperature. The findings of this study provide the basis for future research on the population status of H. coronatus and H. mohnikei in seagrass beds.     

Novel life‐history data for threatened seahorses provide insight into fishery effects

Life‐history variables for three incidentally captured species of seahorse (Kellogg's seahorse Hippocampus kelloggi, the hedgehog seahorse Hippocampus spinosissimus and the three‐spot seahorse Hippocampus trimaculatus) were established using specimens obtained from 33 fisheries landing sites in Peninsular Malaysia. When samples were pooled by species across the peninsula, sex ratios were not significantly different from unity, and height and mass relationships were significant for all species. For two of these species, height at physical maturity (H_M) was smaller than the height at which reproductive activity (H_R) commenced: H. spinosissimus (H_M = 99·6 mm, H_R = 123·2 mm) and H. trimaculatus (H_M = 90·5 mm, H_R = 121·8 mm). For H. kelloggi, H_M could not be estimated as all individuals were physically mature, while H_R = 167·4 mm. It appears that all three Hippocampus spp. were, on average, caught before reproducing; height at 50% capture (H_C) was ≥H_M but ≤H_R. The results from this study probe the effectiveness of assessment techniques for data‐poor fisheries that rely heavily on estimates of length at maturity, especially if maturity is poorly defined. Findings also question the sustainability of H. trimaculatus catches in the south‐west region of Peninsular Malaysia, where landed specimens had a notably smaller mean height (86·2 mm) and markedly skewed sex ratio (6% males) compared with samples from the south‐east and north‐west of the peninsula.     

Life history and ecology of seahorses: implications for conservation and management

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.     

Life history and population dynamics of an endangered seahorse (Hippocampus capensis) within an artificial habitat

Species-specific life-history information is critical for successful conservation, particularly in establishing an accurate baseline status. Obtaining such information is challenging for most species, but in particular for rare and threatened marine species. To facilitate future conservation of the endangered Knysna seahorse (Hippocampus capensis) this study aimed to determine important life-history information for this species. Visible implant fluorescent elastomer (VIFE) tags were used to mark 78 seahorses within a residential marina estate in the Knysna estuary, South Africa, in February 2018. Using a mark-resight approach, the size and movement patterns of the population and growth rate of seahorses were determined over a 14-month period. The closed population estimate for H. capensis, within Thesen Islands Marina, was estimated to be 134 (118–152 95% C.I. ) in February 2018 compared to only 72 (48–108 95% C.I. ) in February 2019. The species showed rapid initial growth with males and females having similar rates of growth based on the specialised von Bertalanffy growth function model. The importance of Reno mattresses as a habitat for H. capensis was confirmed based on the high abundance and site fidelity of the population, which emphasises the conservation potential of heavily modified environments for threatened seahorse species. The use of VIFE tags was deemed effective in studying this endangered seahorse and allowed the collection of important information for this species which can be used in future Red List assessments and conservation actions.     

The catch and trade of seahorses in Vietnam

Catch monitoring and surveys were used to assess the seahorse trade in Vietnam. Despite low daily catch rates, potentially 6.5 t of dried seahorses (~2.2 million seahorses) were taken annually as bycatch by trawlers operating out of five coastal provinces of Vietnam. Individual seahorse catches were collated by a few local buyers, who supplied wholesalers in three major markets: Ho Chi Minh City, Hai Phong City and Da Nang. Domestic consumption was small and most seahorses were exported, generally through unofficial and unregulated channels across the northern border into Guangxi province of China. Overall, the seahorse trade was of low economic value to Vietnam, but may constitute an important source of income to upper level buyers and exporters. Most fishers and buyers surveyed reported that seahorse catch had declined over time. This paper should help in meeting the new CITES requirements – through implementation of an Appendix II listing in 2004 – that all international trade in seahorses must be monitored and managed for sustainability.     

Serial monogamy in the European long-snouted seahorse Hippocampus guttulatus

Seahorses (Hippocampus spp.) are non-sex-role-reversed members of the Syngnathidae family that provide extensive brood care. Previous studies of seahorses have revealed monogamy within a single brood, but their longer term mating system had not been comprehensively evaluated. The parental contribution to 29 wild-born broods of Hippocampus guttulatus, sampled from six Portuguese populations with differing seahorse densities and sex ratios, was assessed using microsatellite DNA markers. To assess the longer term genetic mating system of this species parentage was determined in eleven broods sampled from a captive population over two breeding seasons. Genetic data suggest that this socially polygamous seahorse is serially monogamous across breeding seasons, i.e. monogamous within a season but may switch mates between seasons, and that differing population densities and sex ratios do not affect the mating system.     

New records of the Japanese seahorse Hippocampus mohnikei in Southeast Asia lead to updates in range,habitat and threats

New records of the Japanese seahorse Hippocampus mohnikei from Cambodia, Malaysia, Thailand and Vietnam, along with recently published studies from India and Singapore, have greatly expanded the known range of H. mohnikei within Southeast Asia. These new records reveal novel habitat preferences and threats to H. mohnikei in the region. Although the global conservation status of H. mohnikei is classified as Data Deficient according to the IUCN Red List of Threatened Species, new sightings indicate that this species is found in similar habitats and faces similar threats as other Hippocampus species that are considered Vulnerable.     

Orycteropus (Tubulidentata, Mammalia) from Langebaanweg and Baard's Quarry, Early Pliocene of South Africa

Fossil teeth and bones of aardvarks are relatively common at Langebaanweg, an Early Pliocene site in western Cape Province, South Africa. The remains are compatible in size and most details of morphology to extant Orycteropus afer, and are the earliest fossils attributed to this species. Other Late Miocene to Early Pliocene localities in Africa have yielded smaller species of aardvarks, suggesting that the extant lineage evolved in southern Africa. Morphologically the genus Orycteropus has been remarkably conservative since at least the Early Miocene but it witnessed an overall increase in size through the Neogene. The species O. afer has been morphometrically stable since the Early Pliocene. These observations indicate that the evolutionary process in aardvarks is extremely bradytelic. To cite this article: M. Pickford, C. R. Palevol 4 (2005).     

Novel microsatellite loci in the threatened European long-snouted seahorse (<Emphasis Type="Italic">Hippocampus guttulatus</Emphasis>) for genetic diversity and parentage analysis

The long-snouted seahorse Hippocampus guttulatus is one of the two European seahorse species. We describe the isolation of the first 12 microsatellite loci in this threatened species. These new markers were tested in non-invasive samples of 32 seahorses from NW Spain. The number of alleles ranged from 2 to 15 (mean: 6.3) and expected heterozygosity from 0.031 to 0.912 (mean: 0.500). All loci conformed to Hardy–Weinberg expectations and no genotypic disequilibrium was observed between any pair of loci. The theoretical exclusion probabilities for this set of loci, when no parental information exists or when one parent is known, were 0.973 and 0.998, respectively. This study indicates the usefulness of these novel loci for population analysis and kinship studies in Hippocampus guttulatus. Their potential application is extended to the other European seahorse species, since all loci were successfully cross-amplified in H. hippocampus.     

Seahorse (Hippocampinae) population fluctuations in the Ria Formosa Lagoon,south Portugal

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001–2002, 2008–2009 and 2010–2013) revealed significant population fluctuations in at least one of the two seahorse (Hippocampinae) species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001–2002 v. 2008–2009), long‐snouted seahorse Hippocampus guttulatus populations increased significantly between 2008–2009 surveys and new 2010–2013 surveys. There were no significant differences in H. guttulatus populations between the 2001–2002 and 2010–2013 surveys. In contrast, there were no significant differences in short‐snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttulatus densities were positively correlated with the percentage of holdfast coverage, but with none of the other environmental variables tested. These results highlight the importance of holdfast availability in maintaining stable seahorse populations. While population fluctuations are certainly more promising than a consistent downward decline, such extreme fluctuations observed for seahorses in the Ria Formosa Lagoon could still leave these two species vulnerable to any additional stressors, particularly during low density periods.     

Fisheries and trade of seahorses in Brazil: historical perspective, current trends, and future directions

Seahorses (Hippocampus spp.) are globally threatened by overexploitation and habitat destruction; they are also regarded as susceptible to heavy exploitation due to some of their life-history traits. From an economic perspective, they are fishes with high monetary value and marketability. Seahorses are now listed in Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora), to ensure that the international trade is not detrimental to the survival of wild populations; the effectiveness evaluation of these international controls needs comparable monitoring data, including evaluation of spatial and temporal trends. This study assesses the seahorse trade in Brazil, aiming to detect trends in catch levels, volumes and prices. Our main findings were: the dried trade was unregulated, without formal records, and primarily domestic, although records of unreported exports existed; it was primarily sustained by incidental captures in trawl nets. The live seahorse trade was mainly destined for exports, and regulated through national quotas. Between 2002 and 2009, mean prices for dried seahorses ranged from US$1.06 ± 0.46 (level 1 traders) to US$1.06 ± 0.46 (level 1 traders) to US2.78 ± 0.68 (end-sellers) each, while mean prices for each live seahorse traded on the domestic market (1997–2009) ranged from US$1.13 ± 0.02 (level 1 traders) to US$1.13 ± 0.02 (level 1 traders) to US10.08 ± 1.71 (retailers). Mean declared export price (2006–2008) was 15.57 ± 10.87. Enhanced implementation of the CITES listing in Brazil will require further research, and additional measures to address both direct and indirect fishing pressure on seahorse populations.     

Population dynamics of the long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) in the Mar Menor coastal lagoon

A 10-year monitoring program was developed to quantify the population dynamics of the long-snouted seahorse population in the Mar Menor coastal lagoon. Based on 985 underwater visual censuses, we estimated the long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) population size in the Mar Menor lagoon and its reduction in size in the last decades, as well as the effect of eutrophication crises in 2016 and 2019 on the species. The annual recruitment for the 2013–2020 period was estimated by comparing the relative abundance of early seahorse life stages in the ichthyoplankton. The density ranged from 0.0458 specimens/m³ at the beginning of the sampling period to 0.0004 at the end, showing a statistically significant difference between the three analyzed periods (H_gl=2 = 14.0, p = 0.001). The long-snouted seahorse population from the Mar Menor lagoon exemplifies the impact of fishing activities and human pressure, especially euxinic episodes and habitat destruction. As a result of this, the Mar Menor population has decreased from several million specimens to a few thousand, in only three decades. This species showed considerable resilience, the seahorse population began to recover once fishing activity stopped. In contrast, the long-snouted seahorse showed high vulnerability to habitat loss and an episodic flooding event. Adult seahorses showed preferences for highly complex habitats, especially Caulerpa prolifera–Cymodocea nodosa mixed meadows and habitats of high complexity and anthropogenic origin, such as harbors, jetties, or breakwaters. In contrast, juvenile seahorses preferred monotonous seabeds with low complexity, such as the sandy beds that are characteristic of the Mar Menor lagoon littoral.     

Conservation and management of seahorses and other Syngnathidae

This article analyses the pressures on seahorses and explores conservation responses. It focuses on seahorses (Hippocampus spp.) but also considers pipefishes and seadragons, especially where they can fill gaps in seahorse knowledge. The charisma of many syngnathids can make them good flagship species for threats and solutions in marine conservation. The article combines a synthesis of published literature with new data on the trade in seahorses for traditional medicine, aquarium display and curiosities. Most traded seahorses come from trawl by-catch, although seahorses are also targeted. The total extraction is large, tens of millions of animals annually, and unsustainable. A first review of the effect of habitat change on syngnathids raises many questions, while suggesting that some species may cope better than others. The combination of pressures means that many species of syngnathid are now included in the IUCN Red List of Threatened Species or national equivalents. In addition, seahorse exports from 175 countries are limited to sustainable levels under the Convention on International Trade in Endangered Species (CITES) of Wild Fauna and Flora. Possible conservation measures include marine protected areas, fisheries management, select aquaculture ventures, trade regulation, improved governance (particularly) and consumer engagement.