The influence of mechanical habitat disturbance on the infauna of Zostera marina L. meadows

Eelgrass (Zostera marina) meadows are a common feature in shallow waters along the Norwegian coast, where they provide a habitat for an infaunal community with a high biodiversity. A field experiment, comprised of two different disturbance events, was conducted to investigate the effects mechanical habitat disturbances have on the infauna of Z. marina. The disturbances included the cutting of all the Z. marina leaves at the sediment surface and the removal of entire plants including the rhizomes. This experiment was conducted in three eelgrass meadows in the inner Oslofjord. The faunal composition of macrofauna and meiofauna in the sediment was analyzed after a recovery time of ten months to investigate the effects of the treatments. The infaunal abundance of macrofauna and meiofauna varied between the three studied locations, with the fewest individuals at Sætrepollen, followed by Sandspollen and Hallangspollen with the highest infaunal abundance. The infauna of the cut treatments could not be separated from control samples by univariate or multivariate statistical analysis. The removed treatment resulted in a higher abundance of the gastropod Peringia ulvae and the bivalve Mya arenaria than in the control samples. Each of the Z. marina meadows was characterized by a different abundance and composition of its infauna. Z. marina meadows in the removed patches did not regrow within ten months, what has the potential to change the functioning of the infaunal community. This should be considered for an appropriate management of Zostera marina

Spatial scales of benthic ecosystems in the sub-Arctic Lofoten-Vesterålen region

publishedVersio

Environmental drivers of benthic community structure in a deep sub-arctic fjord system

publishedVersio

Spatial and temporal structure of the meroplankton community in a sub-Arctic shelf system

Paid Open Acces

Small-scale removal of seagrass (<i>Zostera marina</i> L.): effects on the infaunal community

<p>Eelgrass meadows are a common feature in shallow waters along the Norwegian coast, where they provide a habitat for a diverse infaunal community. Recreational boat anchoring and moorings physically scour seagrass and may affect the ecosystem functioning and resilience of the system to natural and anthropogenic disturbances. A small-scale eelgrass (<i>Zostera marina</i>) removal experiment was conducted to study the effects on macro- and meiofauna. Entire plants, including the rhizomes, were removed from 4 m² patches in three eelgrass meadows in the inner Oslofjord in October 2010. Core samples were taken after a recovery period of 10 months, from the removed patches as well as from the surrounding meadow. Macrofauna (>500 μm) and meiofauna (63–500 μm) in the sediment were investigated for possible effects of the eelgrass removal. Macrofauna and meiofauna composition were site specific and therefore location was identified as the main determinant for the infaunal community. The eelgrass did not regrow within the recovery period and bare sediment patches with only single eelgrass shoots were present during the sampling. Our analyses support an influence of the removal on individual species, but not the complete community. In particular one species, the gastropod <i>Peringia ulvae</i>, was encountered in higher numbers in samples from the removed patches than in control samples. From a management perspective, such minor removal of eelgrass, on the scale of square metres, appears to have no long-lasting detrimental effect to the infaunal community in sheltered meadows with muddy sediments.</p

Permafrost and groundwater interaction: current state and future perspective

&lt;p&gt;This study reviews the available and published knowledge of the interactions between permafrost and groundwater. In its content, the paper focuses mainly on groundwater recharge and discharge in the Arctic and the Qinghai-Tibet Plateau. The study revealed that the geochemical composition of groundwater is sitespecific and varies significantly within the depth of the aquifers reflecting the water-rock interactions and related geological history. All reviewed studies clearly indicated that the permafrost thaw causes an increase in groundwater discharge on land. Furthermore, progressing climate warming is likely to accelerate permafrost degradation and thus enhance hydrological connectivity due to increased subpermafrost groundwater flow through talik channels and higher suprapermafrost groundwater flow. In the case of submarine groundwater discharge (SGD), permafrost thaw can either reinforce or reduce SGD, depending on how much pressure changes affecting the aquifers will be caused by the loss of permafrost. Finally, this comprehensive assessment allowed also for identifying the lack of long-term and interdisciplinary in situ measurements that could be used in sophisticated computational simulations characterizing the current status and predicting groundwater flow and permafrost dynamics in the future warmer climate.&lt;/p&gt