Search

The short term impacts of fishing pressure were compared with the variability induced by environmental drivers on quantitative benthic community impact indicators. The different pressures were evaluated through comparative multifactor statistical analyses of their effects on macrofauna indicators in a Baltic Sea area with high natural disturbance. The area is exposed to a wide range of fishing intensities from long term non-fished areas to seasonal and annually frequently fished areas. Such evaluations are important for comparing the influence and short term variability of impact indicators from both demersal fisheries and the environment, including benthic community biodiversity (species richness), density (abundance in number of individuals), biomass, and average individual mean weight, with high spatio-temporal resolution. Environmental drivers include near bottom water current speed, salinity, temperature, and dissolved oxygen concentration, considering habitat specific and seasonal conditions. Demersal fishing-induced impacts were evident for all indicators. The highest fishing impacts were estimated in soft muddy and sandy habitats and in the second quarter of the year for all indicators, considering complex interactions. All environmental drivers, especially, current speed, had significant impacts on all indicators. The significant influences and short term variability caused by environmental drivers were of the same or larger order of magnitude as fishing impacts. Consequently, the short term influence of environmental drivers and seasonal differences in fishing pressure need to be considered when using quantitative benthic fishing impact indicators and identifying areas that are more or less resilient to fishing in relation to short- and long-term fisheries management plans.

De danske stenrev har i over 100 år været udnyttet som en ressource for marine anlægsarbejder og revenes tangskove blev siden alvorligt påvirket af eutrofiering. Udviklingen,med tab af hårdbundshabitater og ringe naturkvalitet på dem der er tilbage, er nu ved at vende. Vandmiljøet viser positive forbedringer, genopretning af enkelte stenrev er gennemført og nye genopretningsprojekter er i støbeskeen.Denne undersøgelse er en af de få, der er gennemført på danske rev, som beskriver artsspecifikke biomasser af flora of fauna samt individantal af fritlevende dyr. Undersøgelserne er gennemført på Hatter Barn i Samsø Bælt og udgjorde en delmængde i det større RevFisk projekt, hvis overordnede formål var at beskrive stenrevs betydning som habitat for fisk.To relativt afgrænsede og dybdemæssigt forskellige kortlagte revstrukturer blev undersøgt på Hatter Barn, hvor dybden er henholdsvis 6-13m og 13-21m. De kvantitative undersøgelser af makroalger og bunddyr blev udført med en dykkerbetjent ”undervandsstøvsuger”. Der blev indsamlet og oparbejdet 12 prøver fra hver revstruktur, hvor dem fra det dybe rev blev opdelt i to grupper. Vi fandt samlede biomasser på 619,6g (± 397,6 g) askefri tørvægt/m2 på sten på det lavvandede plateau, 74,2g (± 26,9 g) på det dybere rev med en stejl skråning og kun 13,7g (± 2,0 g) på stenene neden for stenskråningen. Der varbetydelig forskel i artssammensætning og dominansforhold på de forskellige dybder.Vi fandt signifikante positive sammenhænge mellem den samlede algevegetations biomasse og den samlede faunabiomasse og antal individer af mobile dyr. Sammenhængene var endnu tydeligere mellem rødalgebiomassen og fauna biomasser og antal mobile dyr og rødalgerne var yderligere positivt korreleret med biomasse og antal individer af krebsdyr. På baggrund af de fundne faunabiomasser og undersøgelser af maveindhold i fisk fanget på revet blev fødebiomasser og fødeproduktion for torsk og havkarusser estimeret for de to revstrukturer på Hatter Barn.

For 2 years, a baseline investigation was carried out to collect reference information of the present environmental status in the Fehmarn Belt and adjacent area. The temporal and spatial variability of phytoplankton was monitored by a combination of monitoring buoys, pigment analysis and fast screening microscopy. The overall phytoplankton succession in the Fehmarn Belt area was found to be influenced primarily by the seasonal changes, where various diatoms dominated the spring and autumn blooms and flagellates like Chrysochromulina sp., Dictyocha speculum and various dinoflagellates were occasionally abundant in late spring and summer. The phytoplankton groups were remarkably uniform horizontally in the investigation area while large differences in both biomasses and composition of individual phytoplankton groups were seen vertically in the water column, especially in the summer periods, in which the two-layer exchange flow between the North Sea and the Baltic Sea is showing a particularly strong stratification in the Fehmarn Belt. The chlorophyll a concentrations ranged continuously from 1 to 3 μg/L at the three permanent buoy stations during the 2 years of monitoring, except for the spring and autumn blooms where chlorophyll a increased up to 18 μg/L in the spring of 2010 and up to 8 μg/L in the autumn of 2009. Recurrent blooms of filamentous cyanobacteria are common during the summer period in the Baltic Sea and adjacent areas, but excessive blooms of cyanobacteria did not occur in 2009 and 2010 in the Fehmarn Belt area. The combination of the HPLC pigment analysis method and monitoring buoys continuously measuring fluorescence at selected stations with fast screening of samples in the microscope proved advantageous for obtaining information on both the phytoplankton succession and dynamic and, at the same time, getting information on duration and intensity of the blooms as well as specific information on the dominant species present both temporally and spatially in the large Fehmarn Belt area.

European seas are encountering an upsurge in competing marine activities and infrastructures. Traditional exploitation such as fisheries, tourism, transportation, and oil production are accompanied by new sustainable economic activities such as offshore windfarms, aquaculture, and tidal and wave energy. One proposed solution to overcome possible competing claims at sea lies in combining these economic activities as part of Multi-Use Platforms at Sea (MUPS). MUPS can be understood as areas at sea, designated for a combination of activities, either completely integrated in a platform or in shared marine space. MUPS can potentially benefit from each other in terms of infrastructure, maintenance, etc. Developing MUPS in the marine environment demands adequate governance. In this article, we investigate four European sites to find out how governance arrangements may facilitate or complicate MUPs. In particular, we apply a framework specifying policy, economic, social, technical, environmental, and legal (PESTEL) factors to explore governance arrangements in four case study sites in different sea basins around Europe ( the Mediterranean Sea, the Atlantic Ocean, the North Sea, and the Baltic Sea). The article concludes with policy recommendations on a governance regime for facilitating the development of MUPS in the future.

In the shallow micro-tidal cove Kertinge Nor, Denmark, a series of field campaigns were conducted from April 1995 to September 1996. During these campaigns, the effect of benthic grazing on phytoplankton concentrations was studied using a dual approach. In the first approach, the density, size distribution and in situ growth of 3 dominant benthic grazers were determined to assess grazing potential and its realisation. In the second approach, the realised grazing potential was estimated from the decline in area-specific chlorophyll a (chl a) concentrations after breakdown of stratification. Forcing functions were monitored continuously during the field campaigns using meteorological data, current meters, temperature loggers and CTD point measurements. In addition, measurements from a local monitoring program in Kertinge Nor were included in the data analysis. Stratification of the water column in the cove was mainly governed by wind speed and solar radiation and occurred 50 to 75% of the time. The potential grazing pressure of the benthic suspension feeders varied but was always greater than that required to graze the entire volume of the cove per day. Using both approaches, it was estimated that realised grazing was ~50% of the potential. The lack of realisation of the grazing potential could be attributed to a lack of mixing of the water column, which resulted in strong vertical gradients in concentrations of chl a. The primary mode of decoupling between benthic suspension feeders and phytoplankton was the stratification of the water column, which created refuges for the phytoplankton.

The eutrophication status of the entire Baltic Sea is classified using a multi-metric indicator- based assessment tool. A total of 189 areas are assessed using indicators where information on reference conditions (RefCon), and acceptable devi- ation (AcDev) from reference condition could be combined with national monitoring data from the period 2001-2006. Most areas (176) are classified as 'affected by eutrophication' and only two open water areas and 11 coastal areas are classified as 'unaf- fected by eutrophication'. The classification is made by application of the recently developed HELCOM Eutrophication Assessment Tool (HEAT), which is described in this paper. The use of harmonized

We review various aspects of the structure and functioning of Danish estuaries from data collected by the National Monitoring Program and from information in published sources. We present data on the physical, chemical, and biological characteristics of estuaries in Denmark, we evaluate the functioning of these systems as filters and transformers of nutrients and we evaluate the outlook for Danish estuaries in the future. Danish estuarine systems are for the most part shallow (

A filter feeding bivalve, represented by the mussel Mytilus edulis, is modelled as a pump, consisting of the bands of lateral cilia along the gdl filaments, and a system of afferent and efferent canals. The relation between pump pressure a H p and pumping rate V was approached through studies of the relations between system resistances and V. The most important resistances distinguished were the frictional resistance m the canal system n H l , the exit loss 'H,,, and the back pressure a H l 2 , imposed on the pump as a means to study the performance characteristics of the gill system. Removal of the laterofrontal cini from the flow path by treatment with serotonin did not measurably affect the frictional resistance, but the cirri presumably constituted a flow-rate-independent resistance nH1, , arising from their beating against the flow. Thus, in steady state, a H p = A H , + AH,, + L H , ~ -t &H1,. A H , and AH,, were linear functions of V, whereas AH,, was a quadratic function of V. At values of V up to the maximum flow rates, n H , and AH,, dominated the system resistance, and the pump characteristic was therefore approximately linear. The interfilament canals and the exhalant siphon presumably constitute the major resistances, in an optimally pumping 'standard' 35 mm mussel, thus constituting head losses of about 0.4 mm and 0.5 mm H,O, respectively. aHi1 amounted to S0.4 mm H 2 0 . The operating point at zero back pressure was estimated at about 1.4 mm H,O. Removal of the laterofrontal cirri from the flow path drastically decreased the efficiency with which S 6 pm algal particles were retained by the gills, but it had no or little effect on the retention of 14 urn particles, supporting previous lndlcations that the laterofrontal cirri do not act as sieves of the through current, but rather as modulators in the process of particle retention. Power output of the 35 mm mussel at zero back pressure was 14 pW, only slightly lower than the maximum of 15 pW. The work done by the pump constituted about 1.5 % of the total aerobic metabolic rate of the mussel.

Data on fecundity and egg mortality of neritic copepods were collected in various seasons, areas and under various hydrographical conditions. On a seasonal basis variations in fecundity (F) were related to temperature rather than to the abundance of phytoplankton (P). However, a strong correlation between F and P was evident when water column stability varied horisontally or temporally (i.e. at a tidal front or subsequent to a storm). Estimated specific egg-mortalities were variable and occasionally very severe, up to 9.1 d-1, implying that down to 10-4% of the eggs survive to hatching. The implications for phenology and distribution of copepods are discussed.

Correlations between rates of ventilation and oxygen consumption in filter feeders are usually interpreted in terms of causal relations, but authors disagree on whether ventilation is regulated to meet respiratory needs or whether oxygen consumption reflects energetic costs of water transport. It seems, however, that neither causality applies, the correlations being determined by physical characteristics of the ventilatory systems. The ventilatory currents both in a tube dwelling worm, Urechis caupo, and in bivalves, such as Mytilus edulis, are laminar, and oxygen in the water is available to the animals solely by diffusion. Various estimates of the diffusive boundary layer 6, developing at the interface between the ventilatory current and the body surface of U. caupo and mantle cavity in M. edulis, were in good agreement. The estimates of 6 amounted to about 0.1 mm, or a small fraction of the thickness of the ventilatory current, indicating that the larger part of the dissolved oxygen in the current is unavailable to the animals. At low rates of ventilation oxygen uptake is governed by the condition of diffusion in the ambient water. Oxygen consumption increases steeply with increasing ventilation until threshold levels are reached, and processes within the body become limiting for the rate of oxygen consumption. Oxygen consumption approaches independency of ventilation at ventilatory rates amounting to only one-fifth or less of the rates of the undisturbedly filtering animal. Regulation of respiration by means of ventilatory regulation thus seems incompatible with filter feeding in habitats that require high rates of water processing. The energetic costs of ventilation are insignificant. Presumably, in most habitats, water processing at low costs is a prerequisite for a life based on filter feeding.

In safety assessments of underground radioactive waste repositories, understanding radionuclide fate in ecosystems is necessary to determine the impacts of potential releases. Here, the reliability of two mechanistic models (the compartmental K-model and the 3D dynamic D-model) in describing the fate of radionuclides released into a Baltic Sea bay is tested. Both are based on ecosystem models that simulate the cycling of organic matter (carbon). Radionuclide transfer is linked to adsorption and flows of carbon in food chains. Accumulation of Th-230, Cs-135, and Ni-59 in biological compartments was comparable between the models and site measurements despite differences in temporal resolution, biological state variables, and partition coefficients. Both models provided confidence limits for their modeled concentration ratios, an improvement over models that only estimate means. The D-model enables estimates at high spatio-temporal resolution. The K-model, being coarser but faster, allows estimates centuries ahead. Future developments could integrate the two models to take advantage of their respective strengths. Electronic supplementary material The online version of this article (doi:10.1007/s13280-013-0398-2) contains supplementary material, which is available to authorized users.

Partitioning of inorganic and organic mercury was studied in the cockles Cardium edule and C. glaucum sampled in a chronically polluted area in the Western Limfjord, Denmark. The proportion of organic mercury in the cockles was linearly correlated to age (and weight) but not to total mercury concentration in the cockles. In 2-, 3- and 4-year-old cockles organic mercury constituted c. 30%, 60%, and 90% of total mercury, respectively. The age correlated proportion of organic mercury is discussed in a food chain context.

The rapidly growing field of three-dimensional software modeling of the Earth holds promise for applications in the geospatial health sciences. Easy-to-use, intuitive virtual globe technologies such as Google Earth™ enable scientists around the world to share their data and research results in a visually attractive and readily understandable fashion without the need for highly sophisticated geographical information systems (GIS) or much technical assistance. This paper discusses the utility of the rapid and simultaneous visualization of how the agents of parasitic diseases are distributed, as well as that of their vectors and/or intermediate hosts together with other spatially-explicit information. The resulting better understanding of the epidemiology of infectious diseases, and the multidimensional environment in which they occur, are highlighted. In particular, the value of Google Earth™, and its web-based pendant Google Maps™, are reviewed from a public health view point, combining results from literature searches and experiences gained thus far from a multidisciplinary project aimed at optimizing schistosomiasis control and transmission surveillance in sub-Saharan Africa. Although the basic analytical capabilities of virtual globe applications are limited, we conclude that they have considerable potential in the support and promotion of the geospatial health sciences as a userfriendly, straightforward GIS tool for the improvement of data collation, visualization and exploration. The potential of these systems for data sharing and broad dissemination of scientific research and results is emphasized.

Particle selection was studied in 10 species of suspension-feeding bivalves by comparing the proportion of algae in the pseudofaeces with that in the surrounding water. All species examined exhibited particle selection, but with different efficiencies. Spisula subtruncata was most efficient, followed, in decreasing order of efficiency, by Corbula gibba, Mytilus edulis (from Wadden Sea) , Acanthocardia echjnata, Aequipecten opercularis, Musculus niger, Crassostrea gigas, Mya arenaria, Cerastoderrna edule, Mytilus e d u l ~ s (from Qresund), and Arctjca ~s landica . Selection efficiency correlated with the size of the labial palps. Particles rejected as pseudofaeces were embedded in mucus, whereas ingested particles were always in free suspension in M. edulis. Apparently, then, different particles have different probabilities of being trapped in mucus, and thus rejected as pseudofaeces. The properties which determine this probability are unknown.

Projektets hovedformål er at undersøge stenrevs potentielle kvælstofeffekt med henblik på at kunne inddrage stenrev som et muligt supplerende virkemiddel i vandplanlægning. Projektet omfatter etablering og analyse af et pilotstenrev i Løgstør Bredning samt analyser af stenrevs kvælstofeffekt på eksisterende stenrev. Projektet vil endvidere bidrage til opfyldelse af mål om opnåelse af gunstig bevaringsstatus for Limfjordens rev. Et modelprojekt fra 2008 viste, at stenrev potentielt og under særlige betingelser kan medvirke til at mindske effekterne af kvælstoftilførsler til visse kystvande (DHI & DMU, 2008). I forbindelse med en efterfølgende screening af potentielt egnede lokaliteter har DHI skønnet, at der på landsplan findes 3-4 lokaliteter, hvor stenrev muligvis kan genetableres med henblik på en kvælstofeffekt (DHI & DCE, 2013). Løgstør Bredning i Limfjorden er et af disse områder. Den potentielle kvælstofeffekt er imidlertid ikke dokumenteret og kvantificeret. På denne baggrund gennemfører Limfjordsrådet i partnerskab med Miljø- og Fødevareministeriet et 5-årigt forsknings- og udviklingsprojekt i Løgstør Bredning, Limfjorden, som skal dokumentere stenrevs potentielle kvælstofeffekt og bidrag til at opnå god økologisk tilstand i samarbejde med Aarhus Universitet, DTU Aqua, DHI, GEUS og NIVA Danmark. Projektet omfatter målinger på eksisterende stenrev samt etableringen af et nyt stenrev og målinger herpå. Projektet vil bidrage til at genoprette naturtypen stenrev og dermed også bidrage til at forbedre Natura 2000 områdets bevaringsstatus. Projektets resultater skal indgå som tekniske anvisninger i forbindelse med virkemiddelkataloget for vandområdeplanerne 2021-2027. Der udarbejdes en samlet syntese af stenrevs potentielle kvælstofeffekt, herunder dokumentation af hvordan organismer på et stenrev reagerer på varierende lysforhold og lav iltkoncentration.