A straightforward conceptual method is proposed to quantitatively assess the seasonal-scale tendency of retreatment or advancement on microtidal beaches by using the backshore/foreshore length ratio. This method is ba...A straightforward conceptual method is proposed to quantitatively assess the seasonal-scale tendency of retreatment or advancement on microtidal beaches by using the backshore/foreshore length ratio. This method is based on measuring the cross-shore profile of a beach when it passes through the “transitional state” that separates the high-from the low-energy season, period during which the morphological characteristics of the beach tend to its equilibrium profile. In order to obtain real measurements of backshore (B) and foreshore (F), the definition of the limits bounding these two important components in subaerial beaches is reviewed and discussed. The approach based on the measurement of the?B/F?length ratio assumes that foreshore and backshore have equivalent lengths in beaches that approximate to their state of morphodynamic equilibrium (B/F?~ 1). A backshore length exceeding the foreshore length is indicative of a state of beach recession, with a?B/F?length ratio > 1. When the foreshore length is greater than the backshore length, the shoreline is advancing or, alternatively, it is developing in a state of morphological confinement,?i.e.?due to the presence of a sea cliff, with a?B/F?< 1. This practical method is then tested against 36 sand and gravel microtidal beach profiles measured along the coasts of Basilicata, in southern Italy. The various “beach states” are summarised into seven classes (I-VII), each identified from specific value intervals of the?B/F?length ratio.展开更多
We investigated rotifer community structure in the Backshore Wetland of the Expo Garden in Shanghai from September 2009 to August 2010.We identified 116 rotifer species,determined the dominant species and their relati...We investigated rotifer community structure in the Backshore Wetland of the Expo Garden in Shanghai from September 2009 to August 2010.We identified 116 rotifer species,determined the dominant species and their relationships with environmental factors,and community diversity indices.Polyarthra trigla was the most common species over the four seasons and proportionally most dominant in spring and autumn,whereas Cephalodella exigua and Keratella cochlearis were the most dominant species in winter and summer,respectively.There was seasonal variability in species numbers,with the highest numbers in summer,followed by autumn and winter.The mean annual density was 815±1346 ind./L and the biomass was 0.3649±0.4940 mg/L.There were significant differences between months:the highest density(2723±2926 ind./L)and biomass(0.7938±0.8197 mg/L)occurred in June,while the lowest density(238±271 ind./L)and biomass(0.0476±0.0429 mg/L)occurred in May.Canonical correspondence analysis(CCA)indicated that temperature,pH,nitrite nitrogen(NO2-N),and total phosphorus(TP)were the most important abiotic factors affecting rotifer distribution.Our research showed that the adaptability of the rotifers to temperature was the important factor.展开更多
Phytoplankton community structure,abundance,and species'spatial and temporal distributions were examined for the Backshore Wetland of Expo Garden in Shanghai from September 2009 to August 2010.A total of 371 phyto...Phytoplankton community structure,abundance,and species'spatial and temporal distributions were examined for the Backshore Wetland of Expo Garden in Shanghai from September 2009 to August 2010.A total of 371 phytoplankton species were identified from 109 genera 8 phyla.There were 18 dominant species in total,and Phormidium tenue was dominant during four seasons.The mean annual abundance and biomass were 711.11×10^(4) cells/L and 5.70 mg/L,respectively.The seasonal changing trend of existing stocks was bimodal,with main peaks of density and biomass occurring in the winter and a secondary peaks occurring in the summer.The Shannon–Wiener diversity index(H′),the Margalef species richness index(D),and Pielou's species evenness index(J)showed a clear seasonal trend.All of the indices showed a changing pattern,with the highest recorded values from the summer to autumn and the lowest recorded values from the winter to spring.The canonical correspondence analysis(CCA)showed that environmental factors,including water temperature,nitrate nitrogen,and pH were the main influencing factors to the change of phytoplankton community structure in the Backshore Wetland of Expo Garden in Shanghai.展开更多
文摘A straightforward conceptual method is proposed to quantitatively assess the seasonal-scale tendency of retreatment or advancement on microtidal beaches by using the backshore/foreshore length ratio. This method is based on measuring the cross-shore profile of a beach when it passes through the “transitional state” that separates the high-from the low-energy season, period during which the morphological characteristics of the beach tend to its equilibrium profile. In order to obtain real measurements of backshore (B) and foreshore (F), the definition of the limits bounding these two important components in subaerial beaches is reviewed and discussed. The approach based on the measurement of the?B/F?length ratio assumes that foreshore and backshore have equivalent lengths in beaches that approximate to their state of morphodynamic equilibrium (B/F?~ 1). A backshore length exceeding the foreshore length is indicative of a state of beach recession, with a?B/F?length ratio > 1. When the foreshore length is greater than the backshore length, the shoreline is advancing or, alternatively, it is developing in a state of morphological confinement,?i.e.?due to the presence of a sea cliff, with a?B/F?< 1. This practical method is then tested against 36 sand and gravel microtidal beach profiles measured along the coasts of Basilicata, in southern Italy. The various “beach states” are summarised into seven classes (I-VII), each identified from specific value intervals of the?B/F?length ratio.
基金Project of Shanghai Municipal Committee of Fisheries Animal Genetics and Breeding Center of Shanghai Collaborative Innovation Center(ZF1206)National Science and Technology Commission of Scientific and Technological Research of Expo special(2005ba908b23)Shanghai Science and Technology Commission Expo special(05dz05823)。
文摘We investigated rotifer community structure in the Backshore Wetland of the Expo Garden in Shanghai from September 2009 to August 2010.We identified 116 rotifer species,determined the dominant species and their relationships with environmental factors,and community diversity indices.Polyarthra trigla was the most common species over the four seasons and proportionally most dominant in spring and autumn,whereas Cephalodella exigua and Keratella cochlearis were the most dominant species in winter and summer,respectively.There was seasonal variability in species numbers,with the highest numbers in summer,followed by autumn and winter.The mean annual density was 815±1346 ind./L and the biomass was 0.3649±0.4940 mg/L.There were significant differences between months:the highest density(2723±2926 ind./L)and biomass(0.7938±0.8197 mg/L)occurred in June,while the lowest density(238±271 ind./L)and biomass(0.0476±0.0429 mg/L)occurred in May.Canonical correspondence analysis(CCA)indicated that temperature,pH,nitrite nitrogen(NO2-N),and total phosphorus(TP)were the most important abiotic factors affecting rotifer distribution.Our research showed that the adaptability of the rotifers to temperature was the important factor.
文摘Phytoplankton community structure,abundance,and species'spatial and temporal distributions were examined for the Backshore Wetland of Expo Garden in Shanghai from September 2009 to August 2010.A total of 371 phytoplankton species were identified from 109 genera 8 phyla.There were 18 dominant species in total,and Phormidium tenue was dominant during four seasons.The mean annual abundance and biomass were 711.11×10^(4) cells/L and 5.70 mg/L,respectively.The seasonal changing trend of existing stocks was bimodal,with main peaks of density and biomass occurring in the winter and a secondary peaks occurring in the summer.The Shannon–Wiener diversity index(H′),the Margalef species richness index(D),and Pielou's species evenness index(J)showed a clear seasonal trend.All of the indices showed a changing pattern,with the highest recorded values from the summer to autumn and the lowest recorded values from the winter to spring.The canonical correspondence analysis(CCA)showed that environmental factors,including water temperature,nitrate nitrogen,and pH were the main influencing factors to the change of phytoplankton community structure in the Backshore Wetland of Expo Garden in Shanghai.
