Dynamics of population structure of two species of Echinogammarus genus (Gammaridae, Amphipoda) from Laspi Bay (Crimea, Black Sea)

The investigation of population structure of abundant species of invertebrata in coastal waters is important for estimation and prediction of life of coastal ecosystems. Population structure of two abundant species of Amphipoda (Echinogammarus karadagiensis Grintsov, 2009 and Echinogammarus foxi (Schellenberg, 1928)) from coastal waters of sand-gravel beach was investigated. Specimens were collected from sand-gravel samples. 50 specimens were collected and analyzed in each sample. Some important elements of population structure (length of specimens, proportion of adult male and female, proportion of adult and juvenile specimens, number of eggs in females) were investigated.

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The role of the isolation of the marginal seas during the Pleistocene in the genetic structure of black sea bream Acanthopagrus schlegelii (Bleeker, 1854) in the coastal waters of Japan

PeerJ ◽

10.7717/peerj.11001 ◽

2021 ◽

Vol 9 ◽

pp. e11001

Author(s):

Yutaro Yamashita ◽

Gustavo Sanchez ◽

Kentaro Kawai ◽

Satoshi Tomano ◽

Hiroki Fujita ◽

...

Keyword(s):

Population Structure ◽

Pacific Ocean ◽

Black Sea ◽

Coastal Waters ◽

Sea Bream ◽

The Black Sea ◽

Northwestern Pacific ◽

Marginal Seas ◽

Coastal Marine ◽

Japanese Waters

The black sea bream Acanthopagrus schlegelii (Bleeker, 1854) is a commercially important species in Japanese waters. Assessing its population structure is essential to ensure its sustainability. In the Northwestern Pacific, historical glacial and interglacial periods during the Pleistocene have shaped the population structure of many coastal marine fishes. However, whether these events affected the population of black sea bream remains unknown. To test this hypothesis and to assess the population structure of black sea bream, we used 1,046 sequences of the mitochondrial control region from individuals collected throughout almost the entire Japanese coastal waters and combined them with 118 sequences from populations distributed in other marginal seas of the Northwestern Pacific Ocean. As in other coastal marine fish with similar distribution, we also found evidence that the glacial refugia on the marginal seas prompted the formation of three lineages in black sea bream. These lineages present signatures of population growth that coincided with the interglacial periods of the Pleistocene. While the origin of Lineages B and C remains unclear, the higher relative frequency of Lineage A in the southernmost location suggests its origin in the South China Sea. The non-significant pairwise ΦST and AMOVA of Japanese populations and the presence of these three lineages mixed in Japanese waters; strongly suggest that these lineages are homogenized in both the Sea of Japan and the Pacific Ocean. Our results indicate that the black sea bream should be managed as a single stock in Japan until the strength of connectivity in contemporary populations is further addressed using non-coding nuclear markers.

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Dynamics of population structure of the amphipod Dexamine thea (Dexaminidae, Amphipoda), a new species for the black sea, in the coastal areas of laspi bay (Black Sea, Sevastopol)

Russian Journal of Biological Invasions ◽

10.1134/s2075111714010056 ◽

2014 ◽

Vol 5 (1) ◽

pp. 18-20

Author(s):

V. A. Grintsov

Keyword(s):

Population Structure ◽

New Species ◽

Black Sea ◽

Coastal Areas ◽

The Black Sea ◽

Dynamics Of Population ◽

A New Species

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Population structure and reproductive biology of the smalltail shark (Carcharhinus porosus) off Maranhão (Brazil)

Marine and Freshwater Research ◽

10.1071/mf98127 ◽

1999 ◽

Vol 50 (5) ◽

pp. 383 ◽

Cited By ~ 11

Author(s):

Rosangela Lessa ◽

Francisco Santana ◽

Roberto Menni ◽

Zafira Almeida

Keyword(s):

Population Structure ◽

Coastal Waters ◽

Age Distribution ◽

Shallow Waters ◽

Female Size ◽

Male And Female ◽

Pregnant Females ◽

Nidamental Gland ◽

Elasmobranch Species ◽

Northern Brazil

C. porosus is common throughout the year in shallow waters off the Maranhão coast, northern Brazil, where it is the most abundant elasmobranch species. Of 1128 smalltail sharks collected from June 1984 to November 1987 in gill-nets from coastal waters, ~80% were juveniles. Male and female numbers did not differ from a 1:1 ratio. Modal classes were 50.0–60.0 cm (TL) for both sexes. A 120.5 cm female was the largest specimen caught and a 29.4 cm male was the smallest. Age distribution for the whole sample ranged from 0 to >12 years. The length–weight relationship did not differ significantly between the sexes. Diameter of ovarian follicles, presence of eggs/embryos and nidamental gland traits in females point to a major physiological change toward maturity at about 70.0 cm. Vitellogenesis was first observed at 63.0 cm, and the smallest of the six pregnant females was 70.0 cm. There was a significant relationship between the number of embryos and female size. From September to November, ovulation and newborns were observed in catches. Resumo. Carcharhinus porosus é comum ao longo do ano em águas rasas do norte do Brasil onde é a espécie mais abundante entre os elasmobrânquios. De 1128 exemplares coletados em águas costeiras de junho 1984 a novembro 1987 em redes de emalhar ~80% eram jovens. O número de machos e fêmeas não diferiu da razão 1:1. A classe modal foi a de 50.0–60.0 cm para ambos os sexos. Uma fêmea de 120.5 e um macho de 29.4 cm corresponderam ao maior e ao menor exemplar capturado, respectivamente. A distribuição de idades na amostra total variou de 0 a >12 anos. Arelação peso–comprimento não mostrou diferenças significativas entre os sexos. O diâmetro dos ovócitos, presença de embriões/ovos e largura da glândula nidamentária nas fêmeas indica aquisição da maturidade em 70.0 cm. Foi estabelecida uma relação significativa entre o número de embriões e o tamanho das femeas. Entre setembro e novembro ocorre a ovulação e recém nascidos foram observados nas capturas.

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