Effect of sedimentological and hydrodynamical changes in the intertidal areas of the Oosterschelde estuary (SW Netherlands) on distribution, density and biomass of five common macrobenthic species: Spio martinensis (Mesnil), Hydrobia ulvae (Pennant), Arenicola marina (L.), Scoloplos armiger (Muller) and Bathyporeia sp.

Hydrobiologia ◽  
1994 ◽  
Vol 282-283 (1) ◽  
pp. 235-249 ◽  
Author(s):  
J. Coosen ◽  
J. Seys ◽  
P. M. Meire ◽  
J. A. M. Craeymeersch
Keyword(s):  
Distribution Density ◽  
Arenicola Marina ◽  
Oosterschelde Estuary ◽  
Hydrobia Ulvae ◽  
Spio Martinensis ◽  
Density And Biomass

scholarly journals Distribution, Density, and Biomass of Introduced Small Mammals in the Southern Mariana Islands

2009 ◽  
Vol 63 (2) ◽  
pp. 205-222 ◽  
Author(s):  
Andrew S. Wiewel ◽  
Amy A. Yackel Adams ◽  
Gordon H. Rodda
Keyword(s):  
Small Mammals ◽  
Distribution Density ◽  
Mariana Islands ◽  
Density And Biomass

scholarly journals LAJU TANGKAP, KOMPOSISI, SEBARAN, KEPADATAN STOK DAN BIOMASA UDANG DI LAUT JAWA

2017 ◽  
Vol 22 (4) ◽  
pp. 243
Author(s):  
Tirtadanu Tirtadanu ◽  
Suprapto Suprapto ◽  
Tri Ernawati
Keyword(s):  
Carapace Length ◽  
Distribution Density ◽  
Catch Rate ◽  
Biomass Estimation ◽  
Composition Distribution ◽  
Metapenaeus Ensis ◽  
Penaeus Semisulcatus ◽  
Java Sea ◽  
Penaeid Shrimps ◽  
Density And Biomass

Penangkapan udang di Laut Jawa telah dilakukan sejak lama dan aktivitasnya berpengaruh besar terhadap perubahan stok dan ekologi perairan. Data dan informasi terbaru terkait laju tangkap, komposisi, sebaran dan kepadatan stok udang diperlukan sebagai dasar dalam pengelolaan sumberdaya udang yang berkelanjutan di Laut Jawa. Tujuan penelitian adalah untuk mengetahui laju tangkap, komposisi, sebaran dan kepadatan stok udang di Laut Jawa. Penelitian dilakukan pada Oktober dan November 2015 dengan menggunakan armada Kapal Riset Madidihang 02 di Laut Jawa. Kepadatan stok diestimasi dengan metode sapuan. Enam belas spesies dari 6 genera udang ditemukan di Laut Jawa dengan lima spesies dominan adalah Metapenaeopsis palmensis (53,33%), Metapenaeus ensis (14,98%), Trachypenaeus malaiana (12,89%), Penaeus semisulcatus (6,16%) dan Metapenaeopsis stridulans (5,21%). Rerata panjang karapas udang yang dominan yaitu udang krosok (M. palmensis) adalah 14 mm untuk udang jantan dan 16 mm untuk udang betina. Secara horisontal, penyebaran udang tertinggi ditemukan di perairan selatan Kalimantan Tengah, perairan utara Sumenep, perairan sekitar Pulau Bawean dan utara Tegal. Berdasarkan pengalaman, penyebaran udang tertinggi ditemukan pada kedalaman 40-50 m. Rerata kepadatan stok udang di Laut Jawa sebesar 21,34 ± 16,81 kg/km2 dan laju tangkap sebesar 1 ± 0,5 kg/jam. Estimasi biomasa udang di Laut Jawa sebesar 9.938 ton. Shrimp resources in Java Sea have been exploited for years and its activity affected the changes of shrimps stock abundance  and aquatic ecology. Data and the latest information about catch rate, composition, distribution, density and biomass of shrimps were required as a basis of sustainable management in Java Sea. The aim of this research were to determine catch rate, composition, distribution, density and biomass of shrimps in Java Sea. The Research was conducted from October until November 2015 using Research vessel Madidihang 02 in Java Sea. Swept Area Method was used for stock density estimation. The aims of this research were to determine catch rate, composition, distribution and stock density of shrimps in Java Sea. Sixteen species from 6 genera of shrimps were found in Java Sea. The Dominant species of shrimps in Java sea were Metapenaeopsis palmensis (53,33%), Metapenaeus ensis (14,98%), Trachypenaeus malaiana (12,89%), Penaeus semisulcatus (6,16%) and Metapenaeopsis stridulans (5,21%). The most dominant shrimps caught were velvet shrimps (M. palmensis) of the average size of 14 mm carapace length for males and 16 mm carapace length for females. The highest stock density of Penaeid shrimps were found in the southern waters of Kalimantan Central, northern waters of Sumenep and the waters around Bawean island and Northern waters of Tegal. The highest stock density were found in depth of 40-50 m. The average density of Penaeid shrimps in the Java sea was 21.34 ± 16.81 kg/km2 and the catch rate was 1±0,5 kg/hour. Biomass estimation of shrimps in Java Sea were 9.938 ton.

Effects of marine reserves on predator-prey interactions in central California kelp forests

2020 ◽  
Vol 655 ◽  
pp. 139-155
Author(s):  
DC Yates ◽  
SI Lonhart ◽  
SL Hamilton
Keyword(s):  
Species Interactions ◽  
Size Structure ◽  
Marine Reserves ◽  
Mortality Rates ◽  
Kelp Forests ◽  
Negative Effects ◽  
Central California ◽  
Invertebrate Predators ◽  
Predatory Fishes ◽  
Density And Biomass

Marine reserves are often designed to increase density, biomass, size structure, and biodiversity by prohibiting extractive activities. However, the recovery of predators following the establishment of marine reserves and the consequent cessation of fishing may have indirect negative effects on prey populations by increasing prey mortality. We coupled field surveys with empirical predation assays (i.e. tethering experiments) inside and outside of 3 no-take marine reserves in kelp forests along the central California coast to quantify the strength of interactions between predatory fishes and their crustacean prey. Results indicated elevated densities and biomass of invertebrate predators inside marine reserves compared to nearby fished sites, but no significant differences in prey densities. The increased abundance of predators inside marine reserves translated to a significant increase in mortality of 2 species of decapod crustaceans, the dock shrimp Pandalus danae and the cryptic kelp crab Pugettia richii, in tethering experiments. Shrimp mortality rates were 4.6 times greater, while crab mortality rates were 7 times greater inside reserves. For both prey species, the time to 50% mortality was negatively associated with the density and biomass of invertebrate predators (i.e. higher mortality rates where predators were more abundant). Video analyses indicated that macro-invertivore fishes arrived 2 times faster to tethering arrays at sites inside marine reserves and began attacking tethered prey more rapidly. The results indicate that marine reserves can have direct and indirect effects on predators and their prey, respectively, and highlight the importance of considering species interactions in making management decisions.

Conservation and Restoration of Grasslands

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Community Assembly ◽  
Woody Plants ◽  
Woody Plant ◽  
Priority Effects ◽  
Woody Plant Encroachment ◽  
Humpty Dumpty ◽  
Alternate States ◽  
Density And Biomass ◽  
Acid Test ◽  
Stocking Rates

Conservation programs alter herbivore stocking rates and find and protect the remaining areas that have not been plowed or converted to crops. Restoration is an ‘Acid Test’ for ecology. If we fully understand how grassland systems function and assemble after disturbance, then it should be easy to restore them after they have been degraded or destroyed. Alternatively, the idea that restorations will not be equivalent to remnants has been termed the ‘Humpty Dumpty’ hypothesis—once lost, it cannot be put back together again. Community assembly may follow rules, and if these rules are uncovered, then we may be able to accurately predict final species composition after assembly. Priority effects are sometimes found depending on species arrival orders, and they can result in alternate states. Woody plant encroachment is the increase in density and biomass of woody plants, and it is strongly affecting grassland C and water cycles.

Suppression of Weed Occurrence in a Five-year Corn-earthworm Coculture System

Weed Science ◽  
2020 ◽  
pp. 1-23
Author(s):  
Tao Li ◽  
Jiequn Fan ◽  
Zhenguan Qian ◽  
Guohui Yuan ◽  
Dandan Meng ◽  
...  
Keyword(s):  
Weed Species ◽  
Ecological Benefits ◽  
Economic Output ◽  
Green Foxtail ◽  
Weed Diversity ◽  
The Mean ◽  
Common Purslane ◽  
Species Specific ◽  
Density And Biomass ◽  
Successive Experiment

Abstract The use of a corn-earthworm coculture (CE) system is an eco-agricultural technology that has been gradually extended due to its high economic output and diverse ecological benefits for urban agriculture in China. However, the effect of CE on weed occurrence has received little attention. A five-year successive experiment (2015 to 2019) was conducted to compare weed occurrence in CE and a corn (Zea mays L.) monoculture (CM). The results show that CE significantly decreased weed diversity, the dominance index, total weed density and biomass, but increased the weed evenness index. The five-year mean number of weed species per plot was 8.4 in CE and 10.7 in CM. Compared to those in CM, the five-year mean density and biomass of total weeds in CE decreased by 59.2% and 66.6%, respectively. The effect of CE on weed occurrence was species specific. The mean density of large crabgrass [Digitaria sanguinalis (L.) Scop.], green foxtail [Setaria viridis (L.) Beauv.], goosegrass [Eleusine indica (L.) Gaertn.], and common purslane (Portulaca oleracea L.) in CE decreased by 94.5, 78.1, 75.0, and 45.8%, whereas the mean biomass decreased by 96.2, 80.8, 76.9, and 41.4%, respectively. Our study suggests that the use of CE could suppress weed occurrence and reduce herbicide inputs in agriculture.

scholarly journals The Root-Soil Water Relationship Is Spatially Anisotropic in Shrub-Encroached Grassland in North China: Evidence from GPR Investigation

2021 ◽  
Vol 13 (6) ◽  
pp. 1137
Author(s):  
Xihong Cui ◽  
Zheng Zhang ◽  
Li Guo ◽  
Xinbo Liu ◽  
Zhenxian Quan ◽  
...  
Keyword(s):  
Soil Water ◽  
Root Distribution ◽  
Preferential Flow ◽  
Distribution Density ◽  
Vertical Direction ◽  
Additive Models ◽  
Depth Interval ◽  
Soil Core ◽  
Semi Arid ◽  
Free Area

To analyze the root-soil water relationship at the stand level, we integrated ground-penetrating radar (GPR), which characterized the distribution of lateral coarse roots (>2 mm in diameter) of shrubs (Caragana microphylla Lam.), with soil core sampling, which mapped soil water content (SWC) distribution. GPR surveys and soil sampling were carried out in two plots (Plot 1 in 2017 and Plot 2 in 2018) with the same size (30 × 30 m2) in the sandy soil of the semi-arid shrubland in northern China. First, the survey area was divided into five depth intervals, i.e., 0–20, 20–40, 40–60, 60–80, and 80–100 cm. Each depth interval was then divided into three zones in the horizontal direction, including root-rich canopy-covered area, root-rich canopy-free area, and root-poor area, to indicate different surface distances to the canopy. The generalized additive models (GAMs) were used to analyze the correlation between root distribution density and SWC after the spatial autocorrelation of each variable was eliminated. Results showed that the root-soil water relationship varies between the vertical and horizontal directions. Vertically, more roots are distributed in soil with high SWC and fewer roots in soil with low SWC. Namely, root distribution density is positively correlated with SWC in the vertical direction. Horizontally, the root-soil water relationship is, however, more complex. In the canopy-free area of Plot 1, the root-soil water relationship was significant (p < 0.05) and negatively correlated in the middle two depth intervals (20–40 cm and 40–60 cm). In the same two depth intervals in the canopy-free area of Plot 2, the root-soil water relationship was also significant (p < 0.01) but non-monotonic correlated, that is, with the root distribution density increasing, the mean SWC decreased first and then increased. Moreover, we discussed possible mechanisms, e.g., root water uptake, 3D root distribution, preferential flow along roots, and different growing stages, which might lead to the spatially anisotropic relationship between root distribution and SWC at the stand level. This study demonstrates the advantages of GPR in ecohydrology studies at the field scale that is challenging for traditional methods. Results reported here complement existing knowledge about the root-soil water relationship in semi-arid environments and shed new insights on modeling the complex ecohydrological processes in the root zone.

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