Community structure and ecological distribution of benthic animals in Tien Hai mangrove forest, Northern Vietnam

Mangroves are a diverse and rich ecosystem, in which many animals are associated, including benthos. Species composition and occurrence of these animals are driven by the mangroves and tidal conditions. To examine how the benthic animal is distributed in mangrove habitats from northern Vietnam, two surveys in 2019 were conducted in Tien Hai Wetland Nature Reserve, which resulted in a total of 89 species, belonging to 56 genera and 35 families of zoobenthos. This is the first publication of these animals in the study site. The two major groups of benthic animals in the ecosystem were Crustacea and Mollusca, which occupy 54.02% and 36.78% of the total species, respectively. There are several new records of these animals from the coastal mangroves of Vietnam. Two species were new data for northern Vietnam (Scopimera curtelsoma and Parasesarma eumolpe), and four species were new records for Vietnam (Laemodonta punctigera, Cassidula nucleus, Pythia cecillei and Microtralia alba). Also, the present study shows distributional characteristics of the benthic animal community in mangrove forests. The present study indicates that benthic animals show an increase in species diversity and density from the river mouth to the continent. Seasonally quantitative data of benthic from the study site are the first work in mangrove forests of Vietnam. Recent findings are fundamental data for further studies on zoobenthos and related issues to preserve biodiversity in the mangrove forests in Vietnam.

MỐI QUAN HỆ GIỮA ĐỘNG VẬT ĐÁY CÓ GIÁ TRỊ KINH TẾ CHỦ YẾU VỚI ĐẶC TRƯNG SINH THÁI CỦA ĐẦM THỊ NẠI, VIỆT NAM

Relations between economic zoobenthos species and ecological characteristics of Thi Nai lagoon were reported as results of three surveys carried out during 2014–2015. The results have pointed out 11 zoobenthos species that have primarily economic value at the Thi Nai lagoon (5 bivalve species, 5 crustacea species and 1 gastropoda species). Bivalve group possesses 91% of the entire commercial yield of benthic animal (7,456.9 tons/year), in which Glauconome chinensis and Gari elongata possess dominatingly (possess 90% of the entire commercial yield of bivalves: 6,817 tons/year). Bivalve and gastropoda groups were found in correlation with sandy sediment and mangroves but crustacea group was found in correlation with muddy sand sediments and seagrass. The results of this study will conntribute the scientific basis for further studies on the trophic relationship, food web and data for planning, zoning and appropriate exploitation of fisheries resources.

Trace fossils in Ordovician radiolarian chert successions in the Southern Uplands, Scotland

ABSTRACTRadiolarian chert and associated siliceous claystone in the Southern Uplands of Scotland are examined, in order to study the Great Ordovician Biodiversification Event of benthic animals on the pelagic ocean bottom. Trace fossils which are uncommon, but convincing, are found in the grey chert and siliceous claystone of Gripps Cleuch. These observations constitute firm evidence that large benthic animals which could leave visible trace fossils had colonised the Iapetan Ocean by the late Middle Ordovician, confirming previous studies from Australia for Panthalassa, the other huge ocean. Red chert is, however, a poor recorder of trace fossils, probably because the highly oxidising environment breaks down organic matter, both inhibiting high-density activity of large benthic animals and removing clear traces of benthic animal life.

Reviews and syntheses: the first records of deep-sea fauna – a correction and discussion

The soundings in deep waters of Baffin Bay, together with the recovery of a basket star by John Ross in 1818, was a milestone in the history of deep-sea research. Although the alleged water depths of up to 1950 m were by far not reached, these were nevertheless the first soundings in deep bathyal (to perhaps uppermost abyssal) depths. Furthermore, the recovery of a benthic animal proved that animal life existed at great depths. Yet this was not the first published record of deep-sea fauna as it is often portrayed. This merit goes to accidental catches of the stalked crinoid Cenocrinus asterius that were recovered with fishing lines from upper bathyal environments near Antillean islands. In addition, the description of several deep-sea fishes considerably predated the John Ross episode.

The first records of deep-sea fauna – a correction and discussion

The soundings in deep waters of Baffin Bay, together with the recovery of a basket star by John Ross in 1818, was a milestone in the history of deep-sea research. Although the alleged water depths of up to 1950 m were by far not reached, these were nevertheless the first soundings in deep bathyal (to perhaps uppermost abyssal) depths. Furthermore, the recovery of a benthic animal proved that animal life existed at great depths. Yet this was not the first published record of deep-sea fauna as it is often portrayed. This merit goes to accidental catches of the stalked crinoid Cenocrinus asterius that were recovered with fishing lines from upper bathyal environments near Antillean islands. In addition, the description of several deep-sea fishes considerably predated the John Ross episode.

The Indices of Diversity of Benthic Macroinvertebrates in the Danshui River of Dongjiang (China)

The benthic animal community was examinesd in Danshui River of Dongjiang in November 2013. The river health evaluation system was established, a more comprehensive evaluation of Dongjiang water quality, for the reference in chemical pollutants control and administration.