Description: Increasing anthropogenic activities on land and at sea underline the demand for easily applicable indices to effectively predict human mediated changes in ecosystem functioning. Here, we propose a novel bioirrigation index (IPc) that is based on body mass, abundance, burrow type, feeding type and injection pocket depth of bottom dwelling animals. Results from both community and single-species experimental incubations indicate that IPc is able to predict the bioirrigation rate in different sediment types (mud, fine sand, sand). Further, IPc increased the predictability of biogeochemical cycling (i.e. changing concentrations of phosphate, silicate, ammonium, nitrate and nitrite) under different environmental conditions (i.e. sediment type, temperature, faunal inventory, gradients across the sediment water interface), compared to trait based bioturbation potential (BPc). The trait-based index thus demonstrated robustness in the prediction of animal-mediated functional processes that support biogeochemical functions. Additionally our results confirm that biogeochemical cycling is more closely linked to irrigation traits than to sediment reworking traits. Based on these findings we argue that trait-based indices provide a useful tool for the prediction of ecosystem processes as effect traits provide a direct link to the behavioral mechanisms that drive ecosystem functioning.

Description: Freshwater bivalves of the order Unionoida display an uncommon phenotypic plasticity with high interpopulation and intrapopulation morphological variability, which could be advantageous for coping with habitat modifications. However, unionoids have suffered a marked population decline in different parts of the world in the last decades. A decline in some populations of the South American long‐lived freshwater mussel Diplodon chilensis as a consequence of habitat deterioration has recently been recorded. Ontogenetic allometry and shape variation in shells of D. chilensis from 2 different sites, Paimun lake and Chimehuin river, North Patagonia, Argentina, have been studied. For these purposes, geometric morphometric methods were used. Shell shape shows differences between sites, which the shells from Chimehuin river show less intrapopulation variability; are more elongated, with the anterior part extended upwards and the posterior part downwards; and show a steeper anterior curvature at the umbo compared to those from Paimún lake. These characteristics make shell shape more streamlined to withstand river current. Furthermore, the extended posterior‐ventral part in river shells coincides with higher foot weight that would improve anchoring to the river rocky–sandy substrate. River shells present a bounded eco‐morphotype whereas the higher variability of lake shells includes the “river eco‐morphotype.” Growth is allometric throughout life in both sites and is not sex‐dependent. The success of river repopulation programmes using mussels from lake populations may be increased by transplanting selected individuals that show “river eco‐morphotype.”

Description: Biological hard parts and skeletons of aquatic organisms often archive information of past environmental conditions. Deciphering such information forms an essential contribution to our understanding of past climate conditions and thus our ability to mitigate the climatic, ecological, and social impacts of a rapidly changing environment. Several established techniques enable the visualization and reliable use of the information stored in anatomical features of such biogenic archives, i.e., its growth patterns. Here, we test whether confocal Raman microscopy (CRM) is a suitable method to reliably identify growth patterns in the commonly used archive Arctica islandica and the extinct species Pygocardia rustica (both Bivalvia). A modern A. islandica specimen from Norway has been investigated to verify the general feasibility of CRM, resulting in highly correlated standardized growth indices (r〉0.96; p〈0.0001) between CRM-derived measurements and measurements derived from the established methods of fluorescence microscopy and Mutvei’s solution staining. This demonstrates the general suitability of CRM as a method for growth pattern evaluation and cross-dating applications. Moreover, CRM may be of particular interest for paleoenvironmental reconstructions, as it yielded superior results in the analysis of fossil shell specimens (A. islandica and P. rustica) compared to both Mutvei staining and fluorescence microscopy. CRM is a reliable and valuable tool to visualize internal growth patterns in both modern and fossil calcium carbonate shells that notably also facilitates the assessment of possible diagenetic alteration prior to geochemical analysis without geochemically compromising the sample. We strongly recommend the CRM approach for the visualization of growth patterns in fossil biogenic archives, where conventional methods fail to produce useful results.