scholarly journals Current status and variation trend of seagrass beds in coastal water of Son Tra peninsula, Da Nang city

2021 ◽  
Vol 21 (2) ◽  
pp. 183-189
Author(s):  
Hoa Nguyen Xuan ◽  
Nhu Thuy Nguyen Nhat ◽  
Hieu Nguyen Trung
Keyword(s):  
Species Composition ◽  
Coastal Water ◽  
Shoot Density ◽  
Current Status ◽  
Seagrass Beds ◽  
Variation Trend ◽  
Halophila Ovalis ◽  
Density And Biomass ◽  
Size And Structure

Species composition of seagrasses in coastal water of Son Tra peninsula was less diverse, with three species identified. Halophila ovalis was dominant. The seagrass beds are mainly distributed in Bai Nom and Bai But, with a total area of about 1 ha. The seagrass beds had been seriously degraded in both size and structure. Approximately 9 ha of seagrass beds (90% of total area) disappeared compared with data of 2005. Halophila ovalis had only been distributed at a depth of 2–3 m. Coverage, shoot density, and biomass of seagrass beds had also decreased.

scholarly journals KAJIAN KOMUNITAS EKOSISTEM LAMUN DI SEMENANJUNG TARABITAN KECAMATAN LIKUPANG BARAT KABUPATEN MINAHASA UTARA

2021 ◽  
Vol 9 (2) ◽  
pp. 24
Author(s):  
Risandi D Sitaba ◽  
Carolus P Paruntu ◽  
Billy Theodorus Wagey
Keyword(s):  
Species Composition ◽  
Percent Cover ◽  
Seagrass Beds ◽  
Seagrass Species ◽  
Thalassia Hemprichii ◽  
Enhalus Acoroides ◽  
Halophila Ovalis ◽  
Halodule Uninervis ◽  
Cymodocea Rotundata ◽  
Syringodium Isoetifolium

This research was conducted in the waters of Tarabitan Peninsula, West Likupang North Minahasa using quadants transect method. The purpose of this study was to determine the community structure of seagrass found in that waters as initial information for sustainable management seagrass ecosystem . Field observation was conducted to identify the seagrass species, number of individuals/shoots, percent cover for each type of seagrass in those plotting quadrants. The result of this study documented 6 types of seagrass namely, Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Syringodium isoetifolium, Halophila ovalis and Halodule uninervis. The species composition and distribution of seagrass were varied and was dominated by Thalassia hemprichii was the most dominant seagrass species with a relative density of 55.55%, a relative frequency of 33.67%, 39.92% relative cover, an important value index of 129.03%, a diversity index of 1.30 belonging to this condition, moderate, the uniformity index of 0.72 is classified as high and the dominance index of 0.2 is classified as low. Based on Minister of Environment Decree Republic Indonesia No. 200 of 2004 concerning the status of seagrass beds, the condition of the seagrass beds in the waters of Tarabitan Village is classified as rich / healthy with a cover value of ≥ 60. Keywords : Seagrass Community, Species Composition,  distribution, Tarabitan Peninsula           Penelitian ini dilakukan di perairan Semenanjung Tarabitan Likupang Barat Minahasa Utara dengan menggunakan metode transek kuadran. Tujuan penelitian ini adalah untuk mengetahui struktur komunitas lamun yang terdapat di perairan tersebut sebagai informasi awal untuk pengelolaan lamun secara berkelanjutan. Pengamatan lapangan dilakukan untuk mengidentifikasi jenis lamun, jumlah individu/tegakan, persentase tutupan tiap jenis lamun pada tiap kuadran. Hasil penelitian ini mendokumentasikan 6 jenis lamun yaitu Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Syringodium isoetifolium, Halophila ovalis dan Halodule uninervis. Komposisi jenis dan sebaran lamun bervariasi dan didominasi oleh jenis lamun Thalassia hemprichii merupakan jenis lamun yang paling dominan dengan kerapatan relatif 55,55%, frekuensi relatif 33,67%, tutupan relatif 39,92%, indeks nilai penting 129,03%, indeks keanekaragaman 1,30 tergolong dalam kondisi sedang, indeks keseragaman 0,72 tergolong tinggi dan indeks dominansi 0,2 tergolong rendah. Berdasarkan Keputusan Menteri Lingkungan Hidup Nomor 200 Tahun 2004, kondisi padang lamun di perairan Desa Tarabitan tergolong kaya / sehat dengan nilai tutupan ≥ 60.Kata Kunci: Komunitas Lamun, Komposisi Jenis, Distribusi, Semenanjung Tarabitan

scholarly journals The macrozoobenthos under clam farm (the Black Sea, Sevastopol region)

2018 ◽  
Vol 3 (1) ◽  
pp. 9-22 ◽  
Author(s):  
N. A. Boltacheva ◽  
M. V. Makarov ◽  
L. V. Bondarenko ◽  
M. A. Kovaleva
Keyword(s):  
Species Diversity ◽  
Species Composition ◽  
Black Sea ◽  
Rare Species ◽  
Trophic Structure ◽  
Bivalve Mollusk ◽  
The Black Sea ◽  
Density And Biomass

During 2015–2106 the macrozoobenthos under the clam farm located in the area of Sevastopol was investigated. The aim of the study is to consider species composition, density and biomass of macrozoobenthos in the area of the clam farm. The samples were taken using standard benthic techniques. Relatively low species diversity was observed, with 56 species of macrozoobenthos identified. The density was 500–975 ind. per m², the biomass varied from 0.8 to 381.1 g·m-2. The community of the bivalve mollusk Lucinella divaricata (Linnaeus, 1758) was found. Trophic structure of the community with high quantity of detritus feeders dominated by small polychaetes was determined. The dominating, typical and rare species were identified. Comparison with the data obtained in 1957 in Evpatoriya – Sevastopol area at the same depths and sediments was made.

scholarly journals Selection of the assortment of trees for protective forest plantations

2020 ◽  
Author(s):  
A.I. Petelko ◽  
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Effective Means ◽  
Water Erosion ◽  
Current Status ◽  
Forest Plantations ◽  
Forest Stands ◽  
Protective Forest ◽  
Selection Of ◽  
Hydrographic Network

Reclamation of land on community land funds and the hydrographic network contributes to the most effective means of protecting the soil from water erosion. However, the condition, growth, and productivity of the protective forest stands themselves depend on the species composition. Many years of studies have clearly shown that not all tree species and shrubs can successfully grow on washed soils. Extensive scientific material provides a description of the growth and current status of the studied species, a detailed taxation description of the forest plantations. Of particular value are those species that can grow on eroded lands and protect the soil from erosion.

scholarly journals Reproductive Strategies of the Seagrass Zostera japonica Under Different Geographic Conditions in Northern China

2020 ◽  
Vol 7 ◽  
Author(s):  
Shidong Yue ◽  
Xiaomei Zhang ◽  
Shaochun Xu ◽  
Yu Zhang ◽  
Peng Zhao ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Reproductive Strategies ◽  
Geographic Location ◽  
Dry Weight ◽  
Northern China ◽  
Shoot Density ◽  
Zostera Japonica ◽  
Sexual And Asexual Reproduction ◽  
Density And Biomass

Seagrasses form a unique group of submerged marine angiosperms capable of both sexual and asexual reproduction. The amounts of sexual and asexual reproduction differ within some species relying on geographic location and environmental factors. Here, we studied the reproductive strategies of different geographic Zostera japonica populations, S1 and S2 at Swan Lake lagoon (SLL), and H1 and H2 at Huiquan Bay (HQB), in northern China. The duration of flowering at SLL was longer than at HQB, whereas flowering initiation at HQB occurred earlier than at SLL. In addition, the timing of seed maturation at HQB occurred earlier than at SLL. The allocation to sexual reproduction at SLL was greater than at HQB. The maximum potential seed production was greatest at S1 (22228.52 ± 8832.46 seeds ⋅ m–2), followed by S2 (21630.34 ± 9378.67 seeds ⋅ m–2), H2 (7459.60 ± 1779.33 seeds ⋅ m–2), and H1 (2821.05 ± 1280.57 seeds ⋅ m–2). The seasonal changes in total shoot density and biomass were small at HQB. There was a relatively large number of overwintering shoots at HQB because of the higher average temperature during winter. The allocation to sexual reproduction was lower than at SLL, and no seedlings were observed at HQB during our study. Thus, the population of Z. japonica at HQB was maintained by asexual reproduction. Compared with HQB, the biomass of overwintering shoots at SLL was less than 30 g dry weight ⋅ m–2. The Z. japonica at SLL relied on asexual and sexual reproduction to maintain the population. The results show the necessity of understanding local reproductive strategies before starting restoration and management projects. The study provides fundamental information and guidance for the conservation and restoration of seagrass beds.

Structural Organization and Species Composition of a Lotic Periphyton Community in Response to Experimental Acidification

1989 ◽  
Vol 46 (5) ◽  
pp. 827-835 ◽  
Author(s):  
Dolors Planas ◽  
Louise Lapierre ◽  
Guy Moreau ◽  
Martine Allard
Keyword(s):  
Community Structure ◽  
Species Composition ◽  
Cell Density ◽  
Structural Organization ◽  
Spatial Organization ◽  
Algal Cell ◽  
Periphyton Community ◽  
Experimental Acidification ◽  
Density And Biomass ◽  
And Control

Changes in species composition, richness, diversity, biomass (biovolume), and spatial community structure of a lotic periphyton community were observed under experimental acidification (mean pH 4.5) with and without aluminum, in troughs fed from an oligo-dystrophic creek (mean pH 6.7). in experimental and control troughs, the community was dominated by diatoms throughout the treatment. Achnanthes linearis was dominant in all troughs before treatment as well as in the control during the experiment. Eunotia pectinalis, which was rare in all troughs before treatment, became dominant in the acidified troughs. After 3 mo of acidification, algal cell density and biomass were respectively 30 and 40–70 times higher in the treated troughs as compared with that in the control. The Sow diversity (H = 1.45–2.30) characteristic of the control trough, increased to 3.3 in the treated troughs after 1 mo of acidification, but after 3 mo of experiment the diversity was slightly lower in experimental troughs. In the control trough, spatial organization of the community was characterized by monolayered arrangements during the whole experiment, in both acidified troughs (acid and acid plus aluminum) the community became multilayered (3–4 layers). The increased complexity of the community in the acidified troughs seemed to be related to a decrease in the abundance of grazers in the periphytic community, mainly the collector–gatherers Ephemeroptera and Orthocladiinae.

scholarly journals Boat anchors not OK: Loss of Dugong grass (Halophila ovalis) population structure in Havelock island of Andaman and Nicobar Islands, India

2019 ◽  
Author(s):  
A.K. Mishra ◽  
N.S. Sumantha ◽  
A. Deepak
Keyword(s):  
Population Structure ◽  
Shoot Density ◽  
Canopy Height ◽  
Small Scale ◽  
List Type ◽  
Andaman And Nicobar Islands ◽  
Percentage Cover ◽  
Halophila Ovalis ◽  
Seagrass Ecosystem ◽  
Nicobar Islands

AbstractAnthropogenic disturbance due to deployment of boat anchors and loss of seagrass ecosystem is not well understood in India. So, we used Govind Nagar beach of Havelock Island of Andaman and Nicobar Islands (ANI)to assess the impacts of boat anchors from traditional fishing and recreational activities on the seagrass Halophila ovalis population structure. H. ovalis density, biomass, morphometrics, canopy height and percentage cover were estimated from two stations of Govind Nagar beach i.e., one highly impacted from boat anchors (Station1) and a sheltered station (Station 2). A clear evidence in reduction of shoot density of H. ovalis was observed at station 1, exception was similar apex densities between both stations. H. ovalis morphometrics, such as number of leaves per shoot, leaf length, width and horizontal rhizome length were observed with significant lower values at station 1 compared to the sheltered station 2. Reduction in seagrass morphometrics also resulted in the loss of seagrass canopy height and percentage cover. A clear evidence of loss of seagrass population structure under the influence of physical disturbances caused by boat anchors were observed. We report for the first time the impacts of boat anchors on seagrass ecosystems of India and our results pitch for wider studies across India. The impact of boat anchors is small-scale, but in long-term loss of seagrass ecosystem services will have dire consequences on fish habitat and carbon storage. Therefore, proper management and conservation measures should be taken to prevent the loss of important dugong grass habitats of ANI.HighlightsPhysical disturbances caused by boat anchors decreased the shoot density of H. ovalis by 1.2-fold.1 to 2-fold reduction in canopy height and the morphological features of individual plants were observed due to damage caused by boat anchorsHabitat disturbance reduced 1.6-fold percentage cover of H. ovalis at Havelock Island of Andaman and Nicobar Islands, India

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