Population dynamics of the endangered seahorse Hippocampus reidi Ginsburg, 1933 in a tropical rocky reef habitat

Freret-Meurer, Natalie Villar; Fernández, T.; Okada, Nobuhiro; Vaccani, Amanda do Carmo

doi:10.32800/abc.2018.41.0345

Cited by 8 publications

(16 citation statements)

References 17 publications

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“…Prey availability may influence decisions, considering that the habitat reported here in presents potentially high quality. The association between seahorses and Sargassum vulgare beds has been reported previously [10][11][12]15 and seems to be related to feeding opportunities and protection. The rich fauna associated to Sargassum vulgare beds serves as seahorse prey 15 and seahorse ability to change colour and develop skin filaments allows them to look similar to seaweed, improving preying efficiency by applying camouflage.…”

Section: Discussionsupporting

confidence: 58%

“…Two observers swam (snorkeling) side by side along each transect. Since rocky reefs had up to 2,50m and most of the animals occur at 1,50m deep, [9][10][11] snorkelling was the most adequate diving method. The divers recorded the following data: seahorse species, according to Lourie et al 12 sex, by the presence (male) or absence of the brood pouch (female) (Lourie 2003); height according to Lourie, 12 to characterize specimens as adults (>56mm) or juveniles (<56mm) 11 and, finally, type of holdfast.…”

Section: Methodsmentioning

confidence: 99%

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Gender is not a relevant matter in habitat selection of the longsnout seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

Freret-Meurer¹

2021

JAMB

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Habitat selection in certain species may vary according to context and environmental conditions. Sexual differences regarding habitat use have been reported for several species, such as mammals, birds and fish, and have been explained by protection and food resource contexts. This issue is not well studied in seahorses, but it may provide useful data for the management of threatened species. The Longsnout Seahorse has recently been considered near threatened, but many gaps regarding its habitat use are still noted. Seahorses display a particular breeding characteristic, in which males carry the embryos inside a breeding pouch, therefore leading to supposed careful selection of breeding habitats, avoiding predation risks and choosing habitats with high prey availability. In this context, this study aimed to verify differences in habitat selection between male and female Longsnout Seahorse Hippocampus reidi specimens along the coast of the state of Rio de Janeiro. This study took place at 11 sites along the Rio de Janeiro coastline, in southeastern Brazil. Random belt transects (20x5m) were assessed, searching for seahorses and their holdfasts. Random quadrats (50x50cm) divided into 100 cells/each were placed along the transects and benthic cover was counted, in order to establish substrate availability. Results suggested that males select fewer substrate types than females, but no statistical difference was detected. Both male and female H. reidi specimens select mostly Sargassum vulgare as a frequent habitat. The strong association of H. reidi to these seaweed beds suggests vulnerability concerning the degradation of this habitat.

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Section: Discussionsupporting

confidence: 58%

Section: Methodsmentioning

confidence: 99%

Gender is not a relevant matter in habitat selection of the longsnout seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

Freret-Meurer¹

2021

JAMB

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“…The same was noted for salinity and temperature variations. A possible explanation is that H. reidi occurs in a variety of environments along the Brazilian coast, including mangroves (Mai and Velasco, 2012), open water rocky shores (Freret-Meurer and Oliveira, 2012;Freret-Meurer et al, 2018b), and hypersaline areas (Rosa et al, 2007). In addition, according to Tseng et al (2020), high temperatures (>30°C) had a direct effect on the survival of Seahorse population structure in two estuaries Fernández do Carmo et al…”

Section: Discussionmentioning

confidence: 99%

“…We used the scan method to assess seahorse behavior (Altmann, 1974), which was addressed upon seahorse discovery. Behavior was classified as Foraging, Swimming, Courting, and Resting (Freret-Meurer et al, 2018b). To establish breeding peaks, the reproductive stage was determined according to Lourie (2003), where for males: 0 = just given birth, pouch flabby; 1 = pouch empty, pouch flat; 2 = pregnant, pouch rounded; 3 = about to give birth, pouch extremely rounded and shiny, and for females: 0 = eggs just given away, belly sunken; 1 = no mature eggs, belly flat; 2 = bearing mature eggs, belly slightly raised; 3 = hydrated eggs, belly distended.…”

Section: Methodsmentioning

confidence: 99%

Population structure of the seahorse Hippocampus reidi in two Brazilian estuaries

et al. 2022

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This study aimed to evaluate and compare seasonal variations of Hippocampus reidi population structures in two Brazilian coastal areas. Samples were collected from the rocky shores of Urca and Duas Irmãs Island by freediving along fixed transects. All seahorses observed in the study were recorded, measured, and identified by sex and reproductive stage. Seahorse behavior and fish depth were also registered. All individuals were photo-identified to estimate recapture rates. Holdfast used by seahorses was also recorded. Results showed low densities at both sites; sex ratio and juvenile/adult proportion did not appear to vary with season. The seahorse height differed between the two areas but did not vary with season nor sex. Seahorses in both sites were found in shallow waters (i.e. up to 4 meters), and the depth did not vary by season nor sex. Males were more frequently recaptured than females in both areas. All seahorses were reproductively active year-round, peaking at rainy periods in both areas. The seahorses were more often recorded while resting and seemed to anchor on seaweed. Though in different bays, seahorse population structure and seasonality appeared similar. These data provide useful baseline data for future population assessments.

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“…As seahorses are poor swimmers, the availability of a holdfast is an important habitat factor [123,124], which may explain why some species have no problem in using artificial substrates to cling on [125][126][127][128][129][130][131][132]. Large seahorse species that are commonly fished, such as H. reidi (Figure 3b), are overall less specific in their habitat requirements but share several traits with small congenerics, such as the use of camouflage and an immobile body posture while using the tail as holdfast [29,108] (Figure 3b), but some species are able to change coloration as part of their courtship behavior [109,110] or need for camouflage [103]. A few species are exceptional and show much interspecific variation in coloration, including bright tints [29,111] and biofluorescence [96,112].…”

Section: Body Size and Habitat Requirementsmentioning

confidence: 99%

Diversity of Seahorse Species (Hippocampus spp.) in the International Aquarium Trade

Koning

Hoeksema

2021

Diversity

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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.

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Population dynamics of the endangered seahorse Hippocampus reidi Ginsburg, 1933 in a tropical rocky reef habitat

Cited by 8 publications

References 17 publications

Gender is not a relevant matter in habitat selection of the longsnout seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

Gender is not a relevant matter in habitat selection of the longsnout seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

Population structure of the seahorse Hippocampus reidi in two Brazilian estuaries

Diversity of Seahorse Species (Hippocampus spp.) in the International Aquarium Trade

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