Shoot Biomass Assessments of the Marine Phanerogam Zostera marina for Two Methods of Data Gathering

In order to compare to data gathering methods for shoot biomass assessments of Zostera marina, we compare two allometric models each one representing a data gathering method, one at leaf level and the other in aggregated form. The first allometric model presented leaf dry weight in terms of leaf length as . The second model is expressed as a several-variables version of the allometric Equation (1) dry weight of each leaf in a given shoot can be considered to be a random variable therefore shoot biomass ws can be represented in the form Both models presented similar determination coefficients values of 0.85 and 0.87 respectively. We found no significant differences between parameters α (p = 0.11) and β (p = 0.50) fitted for each model, showing that both equations conduced to the same result. Moreover, both fitted models presented high Concordance Correlation Coefficients of reproducibility () (0.92 and 0.91). We concluded that for shoot weight assessments if larger samples and faster data processing is required then should model of Equation (2) be used. On the other hand, we proposed model of Equation (1) if data at leaf level is required for other endeavors.

Comprehensive Investigation and Assessment of Nutrient and Heavy Metal Contamination in the Surface Water of Coastal Bohai Sea in China

With the rapid development of industrialization and urbanization of coastal regions,eutrophication and metal pollution have caused serious environmental problems in China.To better understand the potential environmental risks associated with nutrients and heavy metals,the surface water was comprehensively investigated in the coastal Bohai Sea.A total of 150 sites were sampled from seven coastal regions,and the concentrations of nutrients(DIN and DIP)and metals(Cd,Pb,Zn,Cu,Cr,As and Hg)in the surface seawater were measured.The results showed that the DIN concentration of about 50%sites exceeded the Grade-I of Seawater Quality Standard of China.Due to high concentrations of DIN,the status of eutrophication was serious in the Bohai Bay and Shuangtaizi Estuary.According to Seawater Quality Standard of China,Pb,Zn,Hg and Cu were the main metal pollutants in the coastal Bohai Sea.There was generally low ecological risk caused by heavy metals,but certain hotspots existed near Shuangtaizi Estuary and Changxingdao Island.

Presence of Sargassum horneri at Todos Santos Bay, Baja California, Mexico: Its Effects on the Local Macroalgae Community

To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.