Habitat dynamics in response to constructional impacts (JadeWeserPort) a biological approach

During the construction of a deep-water port (JadeWeserPort), bathymetry, sediment distribution, and macrofauna community structure were studied in the Inner Jade, a tidal channel located in the southern North Sea. The relationships between macrofauna community structure and natural as well as anthropogenic environmental variables were investigated in this very heterogeneous study area. The manual expert hydroacoustic classification of the backscatter image derived by side scan sonar was successful to detect the different dredging activities and the natural bedforms in the undisturbed areas. The sediment distribution was very patchy and no significant congruence with the hydroacoustic classification could be identified. In contrast, low, but significant relationships between the hydroacoustic classification and the macrofauna community structure as well as the sediment distribution and the macrofauna communities were found. The most important impact on the spatial community structure was the number of days after the last dredging/dumping activity for the JadeWeserPort (JWP), followed by the sediment characteristics explained by grey values of the backscatter image. This study stresses the problems of benthic habitat mapping in such a heterogeneous area. In order to assess the effects of physical disturbance by dredging activities, macrofaunal community compositions between 2002 (before the construction work had begun) and 2010 (during the final construction phase) were compared. The sand extraction for land reclamation and the redirection of the navigation channel changed the bathymetry markedly. While the old navigation channel in the centre of the study area remained mud dominated, a general increase in coarse sediments was detected in 2010. The dynamic nature of the study area in combination with the direct and indirect effects of dredging increased the bathymetric heterogeneity (measured by singlebeam (2002) and multibeam (2010) echo-sounder). In 2010, the macrofauna community structure roughly resembled the different categories of dredging activities. A general increase in macrofaunal abundance and taxa number was observed in 2010, with the exception of the recently dredged area. The structure of the macrofauna community during the port construction phase seemed to be determined by secondary dispersal of the dominant taxa and recolonisation by highly mobile and opportunistic species. The effects of the presence of two adult bivalve species with different feeding modes on the post-settlement dispersal of their juveniles were examined in a flume experiment

Die Wirkung der Fütterung von Haselnussblättern auf die Ausscheidung von Magen-Darm-Wurmeiern bei Ziegen

Feeding hazelnut leaves (Corylus avellana) to first year grazing goats may reduce the egg output of gastrointestinal worms. Previous trials with complete hazelnut bushes support this assumption. Under controlled conditions, the feeding of hazelnut leaves of four weeks, showed no significant differences concerning body weight and fecal egg count between control, low dose and high dose groups, respectively. Anyhow, the great acceptance of hazelnut leaves shows, that browsing does increases animal welfare of goats

Habitatdynamik in Bezug auf bauliche Ma nahmen (JadeWeserPort) ein biologischer Ansatz

During the construction of a deep-water port (JadeWeserPort), bathymetry, sediment distribution, and macrofauna community structure were studied in the Inner Jade, a tidal channel located in the southern North Sea. The relationships between macrofauna community structure and natural as well as anthropogenic environmental variables were investigated in this very heterogeneous study area. The manual expert hydroacoustic classification of the backscatter image derived by side scan sonar was successful to detect the different dredging activities and the natural bedforms in the undisturbed areas. The sediment distribution was very patchy and no significant congruence with the hydroacoustic classification could be identified. In contrast, low, but significant relationships between the hydroacoustic classification and the macrofauna community structure as well as the sediment distribution and the macrofauna communities were found. The most important impact on the spatial community structure was the number of days after the last dredging/dumping activity for the JadeWeserPort (JWP), followed by the sediment characteristics explained by grey values of the backscatter image. This study stresses the problems of benthic habitat mapping in such a heterogeneous area. In order to assess the effects of physical disturbance by dredging activities, macrofaunal community compositions between 2002 (before the construction work had begun) and 2010 (during the final construction phase) were compared. The sand extraction for land reclamation and the redirection of the navigation channel changed the bathymetry markedly. While the old navigation channel in the centre of the study area remained mud dominated, a general increase in coarse sediments was detected in 2010. The dynamic nature of the study area in combination with the direct and indirect effects of dredging increased the bathymetric heterogeneity (measured by singlebeam (2002) and multibeam (2010) echo-sounder). In 2010, the macrofauna community structure roughly resembled the different categories of dredging activities. A general increase in macrofaunal abundance and taxa number was observed in 2010, with the exception of the recently dredged area. The structure of the macrofauna community during the port construction phase seemed to be determined by secondary dispersal of the dominant taxa and recolonisation by highly mobile and opportunistic species. The effects of the presence of two adult bivalve species with different feeding modes on the post-settlement dispersal of their juveniles were examined in a flume experiment

Response of the coccolithophores Emiliania huxleyi and Coccolithus braarudii to changing seawater Mg2+ and Ca2+ concentrations: Mg/Ca, Sr/Ca ratios and δ44/40Ca, δ26/24Mg of coccolith calcite

Calcium and magnesium concentrations in seawater have varied over geological time scales. On short time scales, variations in the major ion composition of seawater influences coccolithophorid physiology and the chemistry of biogenically produced coccoliths. Validation of those changes via controlled laboratory experiments is a crucial step in applying coccolithophorid based paleoproxies for the reconstruction of past environmental conditions. Therefore, we examined the response of two species of coccolithophores, Emiliania huxleyi and Coccolithus braarudii, to changes in the seawater Mg/Ca ratio (≈0.5 to 10 mol/mol) by either manipulating the magnesium or calcium concentration under controlled laboratory conditions. Concurrently, seawater Sr/Ca ratios were also modified (≈2 to 40 mmol/mol), while keeping salinity constant at 35. The physiological response was monitored by measurements of the cell growth rate as well as the production rates of particulate inorganic and organic carbon, and chlorophyll a. Additionally, coccolithophorid calcite was analyzed for its elemental composition (Sr/Ca and Mg/Ca) as well as isotope fractionation of calcium and magnesium (Δ44/40Ca and Δ26/24Mg). Our results reveal that physiological rates were substantially influenced by changes in seawater calcium rather than magnesium concentration within the range estimated to have occurred over the past 250 million years when coccolithophores appear in the fossil record. All physiological rates of E. huxleyi decreased at a calcium concentration above 25 mmol L−1, whereas C. braarudii displayed a higher tolerance to increased seawater calcium concentrations. Partition coefficient of Sr was calculated as 0.36 ± 0.04 (±2σ) independent of species. Partition coefficient of Mg2+ increased with increasing seawater Ca2+ concentrations in both coccolithophore species. Calcium isotope fractionation was constant at 1.1 ± 0.1‰ (±2σ) and not altered by changes in seawater Mg/Ca ratio. There is a well-defined inverse linear relationship between calcium isotope fractionation and partition coefficient of Sr2+ in all experiments, suggesting similar controls on both proxies in the investigated species. Magnesium isotope ratios were relatively stable for seawater Mg/Ca ratios ranging from 1 to 5, with a higher degree of fractionation in Emiliania huxleyi (by ≈0.2‰ in Δ26/24Mg). Although Mg/Ca ratios in the calcite of coccolithophores and foraminifera are similar, the former have considerably higher Δ26/24Mg (by >+3‰), presumably due to differences in calcification mechanisms between the two taxa. These observations suggest, a physiological control over magnesium elemental and isotopic fractionation during the process of calcification in coccolithophores