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Marine ecosystems are under high demand for human use, giving concerns about how pressures from human activities may affect their structure, function, and status. In Europe, recent developments in mapping of marine habitats and human activities now enable a coherent spatial evaluation of potential combined effects of human activities. Results indicate that combined effects from multiple human pressures are spread to 96% of the European marine area, and more specifically that combined effects from physical disturbance are spread to 86% of the coastal area and 46% of the shelf area. We compare our approach with corresponding assessments at other spatial scales and validate our results with European-scale status assessments for coastal waters. Uncertainties and development points are identified. Still, the results suggest that Europe’s seas are widely disturbed, indicating potential discrepancy between ambitions for Blue Growth and the objective of achieving good environmental status within the Marine Strategy Framework Directive.

We modelled and assessed the past, present and predicted future eutrophication status of the Baltic Sea. The assessment covers a 350-year period from 1850 to 2200 and is based on: (1) modelled concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorous (DIP), chlorophyll-a, Secchi depth, and oxygen under four different of nutrient input scenarios and (2) the application of a multi-metric indicator-based tool for assessment of eutrophication status: HEAT 3.0. This tool was previously applied using historical observations to determine eutrophication status from 1901 to 2012. Here we apply HEAT 3.0 using results of a biogeochemical model to reveal significant changes in eutrophication status from 1850 to 2200. Under two scenarios where Baltic Sea Action Plan (BSAP) nutrient reduction targets are met, we expect future good status will be achieved in most Baltic Sea basins. Under two scenarios where nutrient loads remain at 1997-2003 levels or increase, good status will not be achieved. The change from a healthy state without eutrophication problems in the open waters took place in the late 1950s and early 1960s. Following introduction of the first nutrient abatement measures, recovery began in some basins in the late 1990s, whilst in others it commenced in the beginning of the 21st century. Based on model results, we expect that the first basin to achieve a status without eutrophication will be Arkona, between 2030 and 2040. By 2060-2070, a status without eutrophication is anticipated for the Kattegat, Bornholm Basin and Gulf of Finland, followed by the Danish straits around 2090. For the Baltic Proper and Bothnian Sea, a good status with regard to eutrophication will not be expected before 2200. Further, we conclude that two basins are not likely to meet the targets agreed upon and to attain a status unaffected by eutrophication, i.e. the Gulf of Riga and Bothnian Bay. These results, especially the prediction that some basins will not achieve a good status, can be used in support of continuous development and implementation of the regional ecosystem-based nutrient management strategy, the HELCOM Baltic Sea Action Plan.

Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.

This study follows up on a previous assessment of eutrophication status in the Baltic Sea, which covered the period 2001–2006. The updated assessment is based on new eutrophication targets, an improved eutrophication assessment tool (HEAT 3.0) as well as monitoring data for the period 2007–2011. Based on classifications of eutrophication status in all Baltic Sea sub-basins, we reveal that during the assessment period 2007–2011, the entire open Baltic Sea was affected by eutrophication. This is a different conclusion compared to earlier assessments and studies. Whilst the confidence of the assessment was high or moderate in most basins, there were indications of declining confidence in some assessment units and improved confidence in others. The problems in confidence were mainly related to scarcity of in situ monitoring data on chlorophyll-a and Secchi depth. The potential implications of our results, e.g. the expansion of the eutrophic zone and declining confidence in the classifications of eutrophication status, are discussed in relation to the existing Baltic Sea-wide nutrient management strategy as well as future assessment activities.

The objectives of this study are 1) to map the potential cumulative impacts of multiple human activities and stressors on the ecosystems in the transition zone between the North Sea and Baltic Sea, for Danish waters 2) to analyse differences in stressor contribution between the European Union’s Marine Strategy Framework Directive (MSFD, off-shore waters) and Water Framework Directive (WFD, coastal waters), and 3) to assess the local relative importance of stressors for 14 areas along a land-sea gradient, from inner fjords or coastal areas to offshore waters. The mapping of cumulative impacts is anchored in 35 datasets describing a broad range of human stressors and 47 ecosystem components ranging from phytoplankton over benthic communities to fish, seabirds and marine mammals, which we combined by means of a widely used spatial human impact model. Ranking of the stressor impacts for the entire study area revealed that the top five stressors are: ‘Nutrients’, ‘Climate anomalies’, ‘Non-indigenous species’, ‘Noise’ and ‘Contaminants’. The gradient studies showed that some stressors (e.g. ‘Nutrients’, ‘Shipping’ and ‘Physical modification’) have a relatively higher impact within the fjord/estuarine systems whilst others (e.g. ‘Fisheries’, ‘Contaminants’ and ‘Noise’) have relatively higher impact in the open waters. Beyond mapping of cumulative human impacts, we discuss how the maps can be used as an analytical tool to inform ecosystem-based management and marine spatial planning, using the MSFD and WFD as examples.

Nutrient enrichment of coastal marine waters caused by losses of nitrate (NO3 −) from agriculture is an increasing global problem. In the European Union, the Nitrates Directive (ND) of 1991 was meant to be a cornerstone in reducing eutrophication effects in coastal waters downstream from intensively farmed catchments. Although reductions in losses of nitrate have been attained, very few Member States have yet been able to reduce eutrophication effects caused by inputs of NO3 − from agriculture. We report trends in concentrations of NO3 − and chlorophyll-a (Chl-a) in Danish coastal and open marine waters during the period from 1996 to 2011 together with an assessment of eutrophication status based on multiple indicators (e.g. nutrient concentrations, Chl-a, submerged aquatic vegetation and benthic macroinvertebrates). Despite decreasing concentrations of both NO3 −and Chl-a, Danish coastal waters are not yet to be classified as ‘unaffected by eutrophication’. In order to improve future pan-European evaluations of the effectiveness of the ND, we argue for the added value of including indicators and assessment principles from other European Directives, i.e. the Water Framework Directive and the Marine Strategy Framework Directive.

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 approaches and tools currently usedin Nordic countries (Denmark, Finland, Norway andSweden) for integrated assessment of ‘ecological status’sensu the EU Water Framework Directive as well asassessment of ‘eutrophication status’ in coastal and marinewaters. Integration principles for combining indicatorswithin biological quality elements (BQEs) and combiningBQEs into a final-integrated assessment are discussed.Specific focus has been put on combining different types ofinformation into indices, since several methods arecurrently employed. As a consequence of the variety ofmethods used, comparisons across both BQEs and watercategories (river, lakes and coastal waters) can be difficult.Based on our analyses, we conclude that some principlesand methods for integration can be critical and that aharmonised approach should be developed. Further, weconclude that the integration principles applied withinBQEs are critical and in need of harmonisation if we want abetter understanding of potential transition in ecologicalstatus between surface water types, e.g. when riverinewater enters a downstream lake or coastal water body.

We report the development and application of a prototype tool for integrated assessment of chemical status in aquatic environments based on substance- and matrix-specific environmental assessment criteria (thresholds). The Chemical Status Assessment Tool (CHASE) integrates data on hazardous substances in water, sediments and biota as well as bio-effect indicators and is based on a substance- or bio-effect-specific calculation of a 'contamination ratio' being the ratio between an observed concentration and a threshold value. Values1.0 indicate areas potentially 'unaffected', while values1.0 indicate areas potentially 'affected'. These ratios are combined within matrices, i.e. for water, sediment and biota and for biological effects. The overall assessment used a 'one out, all out principle' with regard to each matrix. The CHASE tool was tested in the Baltic Sea and the North Sea in 376 assessment units. In the former, the chemical status was1.0 in practically all areas indicating that all areas assessed were potentially affected. The North Sea included areas classified as unaffected or affected. The CHASE tool can in combination with temporal trend assessments of individual substances be advantageous for use in remedial action plans and, in particular, for the science-based evaluation of the status and for determining which specific substances are responsible for a status as potentially affected.

Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation of marine protected areas and ecosystem-based management, and may prove useful for setting limits on allowable levels of human impact on ecosystems. Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation of marine protected areas and ecosystem-based management, and may prove useful for setting limits on allowable levels of human impact on ecosystems.

I forbindelse med udarbejdelsen af det faglig grundlag for næste generation af vandplaner, har vi udviklet et koncept, som inddrager en række forskellige kriterier for at vurdere miljøtilstanden i marine områder. Kriterierne er: 1) forekomst af iltsvind, 2) potentiel kvælstofbegrænsning, 3) lyssvækkelse i vandsøjlen i forhold til dybdeudbredelse af ålegræs, 4) økologiske effekter af iltsvind og 5) klorofyl koncentration. I projektet er anvendt både empiriske og dynamiske modeller for at kvantificere sammenhængen mellem miljøtilstand og næringsstoftilførsler. I denne præsentation beskrives, hvordan miljømål kan kvantificeres, og hvordan en vægtet model for ovenstående kriterier er anvendt for at beregne den maksimalt acceptable tilførsel (måltilførsel) for opnåelse af ’god økologisk tilstand’. Konceptet er anvendt på 29 vandområder. I præsentationen viser vi, hvordan konceptet virker for områder, som er tæt på ’god økologisk tilstand’ og i områder, hvor der er behov for en meget betydelig reduktion af de nuværende tilførsler. Endvidere kvantificerer vi det samlede indsatsbehov i forbindelse med næste generation af vandplaner. I forbindelse med udarbejdelsen af det faglig grundlag for næste generation af vandplaner, har vi udviklet et koncept som inddrager en række forskellige kriterier for at vurdere miljøtilstanden i marine områder. Kriterierne er: 1) forekomst af iltsvind, 2) potentiel kvælstofbegrænsning, 3) lyssvækkelse i vandsøjlen i forhold til dybdeudbredelse af ålegræs, 4) økologiske effekter af iltsvind og 5) klorofylkoncentration. I projektet er anvendt både empiriske og dynamiske modeller for at kvantificere sammenhængen mellem miljøtilstand og næringsstoftilførsler. I denne præsentation beskrives, hvordan miljømål kan kvantificeres, og hvordan en vægtet model for ovenstående kriterier er anvendt for at beregne den maksimalt acceptable tilførsel (måltilførsel) for opnåelse af ’god økologisk tilstand’. Konceptet er anvendt på 29 vandområder. I præsentationen viser vi, hvordan konceptet virker for områder, som er tæt på ’god økologisk tilstand’ og i områder, hvor der er behov for en meget betydelig reduktion af de nuværende tilførsler. Endvidere kvantificerer vi det samlede indsatsbehov i forbindelse med næste generation af vandplaner.

Scattering alters the path of photons, but ultimately their removal from the water column occurs by absorption by one of four components: water itself, coloured dissolved organic matter (CDOM), phytoplankton pigments or non-algal particulate matter (NAP). We calculated absorption budgets for two fjordal systems, Godthabsfjord (SW Greenland) and Young Sound (NE Greenland), based on these components and evaluated the fate of solar radiation in each system. Absorption by phytoplankton pigment accounted for 15–32% of photons in Godthabsfjord whilst in Young Sound the corresponding fraction was only 5–8%. NAP accounted for 13–25% of absorption in Young Sound and only 7–8% in Godthabsfjord whilst fractions of absorption by CDOM were more similar: 6–13% in Godthabsfjord and 6–18% in Young Sound. In typical temperate estuarine systems, nutrients, CDOM and particulate matter are supplied by riverine sources. Increased nutrient supply will tend to increase productivity whilst increased concentrations of CDOM and particles will increase light attenuation, thereby reducing productivity. The two Greenlandic fjords differ from typical estuarine systems in that their supply of nutrients and particles is decoupled. Freshwater feeding them comes from glacial melt and contains particles but low concentrations of nutrients. New nutrients are supplied by entrainment of oceanic water at the mouths of the fjords and sediment–water exchange of remineralized nutrients. Attenuation and thereby light availability in the two fjords is strongly correlated with turbidity (Godthabsfjord: r2 = 0.90 p

Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.

Integrated assessment of the status of marine biodiversity is and has been problematic compared to, for example, assessments of eutrophication and contamination status, mostly as a consequence of the fact that monitoring of marine habitats, communities and species is expensive, often collected at an incorrect spatial scale and/or poorly integrated with existing marine environmental monitoring efforts. The objective of this Method Paper is to introduce and describe a simple tool for integrated assessment of biodiversity status based on the HELCOM Biodiversity Assessment Tool (BEAT), where interim biodiversity indicators are grouped by themes: broad-scale habitats, communities, and species as well as supporting non-biodiversity indicators. Further, we report the application of an initial indicator-based assessment of biodiversity status of Danish marine waters where we have tentatively classified the biodiversity status of Danish marine waters. The biodiversity status was in no areas classified as “unaffected by human activities.” In all the 22 assessment areas, the status was classified as either “moderately affected by human activities” or “significantly affected by human activities.” Spatial variations in the biodiversity status were in general related to the eutrophication status as well as fishing pressure. &nbsp

Godthåbsfjord i Sydvestgrønland og Young Sund i Nordøstgrønland representerer to forskellige fjordsystemer. Mens Young Sund modtager terrestrisk opløst organisk material (DOM) som kommer langs den østgrønlandske sokkel fra det arktiske hav (ishavet?) så modtager Godthåbsfjord kun lidt terrestrisk organisk material. Her er primær produktion større og det organisk material som findes er primært marint. Fælles for begge fjorde er at tilgængelighed af lys er vigtigt for deres produktivitet. Udover sæsonvariation i overfladeindstråling og isdækning, styres lysnedtrængningen af mængderne og karaktere af de forskellige optiske aktive komponenter: farvede opløste organiske material (CDOM), organiske partikler (inklusive fytoplankton og deres klorofyl indhold), samt uorganiske partikler.Data der indgår i arbejdet inkluderer spektrale lysindstråling igennem vandsøjlen, målt ved en Satlantic profiler på 8 stationer i Godthåbsfjord og 8 stationer i Young Sund. Målinger af optiske egenskaber, spektrale CDOM- (farvede opløste organiske material) og partikulær-absorption, samt koncentrationer af opløste og partikulært kulstof, klorofyl og uorganiske partikulært stof indgår også. En model bliver opstiller som kan forklare den observerede variation i spektral lysindstråling som funktion af variation i optiske aktivt komponenter.Sammensætning af optiskekomponenter og deres variation over vandsøjlen i fjordene varierer med mængden af smeltevand fra gletschere og indtrængning af havvand udefra. Det endelige mål ved arbejdet er at bruge den opstillede model til at vurdere konsekvensen af forøgede smeltevandstilførsel pga. klimændringer for lysnedtrængning og følgende produktivitet.

Analyis of temporal and spatial variation in the in the relationship between light attenuation and Secchi depth in Danish monitoring data There can be found timeseries of Secchi depth measurements in Danish waters which extend relatively far back in time. The Secchi depth measurement is therefore useful in that it allows comparison of present conditions with these older observations. An empirical inverse relationship between Secchi depth and light attenuation coefficient, Kd, has traditionally been used to estimate the light attenuation coefficient from Secchi depth measurements. However, studies have shown that the assumption of a constant inverse relationship between Kd and Secchi depth does not hold. The authors have analyzed measurements of Secchi depth and light attenuation from Danish monitoring data. The data used in our investigation was collected over a continuous period from 1986 to the present. Our study analyses the temporal and spatial variation in the in the relationship between the light attenuation and the secchi disk depth and attempts to give explanations for this variation.

We report the development of a methodology for assessing confidence in ecological status classifications. The method presented here can be considered as a secondary assessment, supporting the primary assessment of eutrophication or ecological status. The confidence assessment is based on scoring the quality of the indicators on which the primary assessment is made. This represents a first step towards linking status classification with information regarding their accuracy and precision. Applied to an existing data set used for assessment of eutrophication status of the Baltic Sea (including the Kattegat and Danish Straits) we demonstrate that confidence in the assessment is Good or High in 149 out of 189 areas assessed (79%). Contrary to our expectations, assessments of the open parts of the Baltic Sea have a higher confidence than assessments of coastal waters. We also find that in open waters of the Baltic Sea, some biological indicators have a higher confidence than indicators representing physical-chemical conditions. In coastal waters, phytoplankton, submerged aquatic vegetation and indicators of physical-chemical conditions have a higher confidence than indicators of the quality of benthic invertebrate communities. Our analyses also show that the perceived weaknesses of eutrophication assessments are due more to Low confidence in reference conditions and acceptable deviations, rather than in the monitoring data.

Som en del af modelgrundlaget for udarbejdelsen af 2. generations vandplanerne er der udviklet lokalspecifikke empiriske modeller for en række danske vandområder. Modellerne beskriver udvalgte vandkvalitetsindikatorer herunder klorofyl a koncentration og lyssvækkelse, der benyttes som mål for potentiel ålegræsdybdegrænse. De uafhængige variable som vi har kombineret er klimavariable (vindenergi, indstråling og afstrømning), vandets fysik og kemi (temperatur, salinitet og vandsøjle stabilitet) og næringsstoftilførsler fra land med forskellig tidforsinkelse. År til år variationen i miljøindikatorerne for de enkelte vandområder er beskrevet med empiriske modeller baseret på partielleast square (PLS) regressioner. Forud for PLS-regressionerne har data været igennem en parameter udvælgelsesproces baseret på jack-knifing og endeligt vurderes modellen på deres evne til at beskrive valideringsdata, som blev isoleret fra det resterende datasæt inden parameterudvælgelsen. På langt de fleste datasæt bidrog næringsstoftilførsler, som forventet, signifikant til forklaringen af de enkelte miljøindikatorer. Det var dog ikke det primære formål at vise, om næringsstoftilførsler har en betydning for de valgte miljøindikatorer. De primære mål var at kvantificere relationerne, både responsstyrke, temporær udbredelse og hvilke klimatiske og fysiske parametre som også har betydning.På baggrund af de fremkomne relationer mellem miljøindikatorerne og næringsstoftilførsler samt kendskab til den aktuelle status og mål for god økologisk tilstand har vi vurderet indsatsbehov for de enkelte vandområder.

Mellem 1980 og 2013 er kvælstof- og fosfortilførsler til de danske farvande reduceret med hhv. 50% og 90%. I den næste generation af vandplaner bliver der kigget fremad og beregnet, hvor meget tilførslerne skal reduceres yderligere for at opnå god økologisk tilstand. Vores mål her er at kigge bagud og dokumentere effekten af reduktioner i kvælstof- og fosforbelastning til de danske fjorde i perioden 1991 til 2011.Der blev udviklet empiriske modeller for at kvantificere relationer mellem næringsstoftilførsler og næringsstofkoncentrationer for 23 målestationer. Modellerne beskriver variation i koncentrationerne som funktion af tilførsler. I modellerne indgår også klima- og fysiske variabler.Vi beskriver yderligere, hvordan relationerne mellem koncentrationer og tilførsler varierer mellem stationerne og diskuterer årsagerne til denne variation. Residualerne fra de empiriske modeller analyseres, og vi diskuterer, om de kan fortælle os noget om tidsforsinkelser mellem næringsstofreduktioner og deres effekter i fjordsystemerne.

Med udgangen af oktober 2014 kunne miljøministeren bringe nyheden om, at Danmark nu har fået sine første vandplaner. For ambitiøse for nogle, og for uambitiøse for andre, men når vi kigger ud over det danske landskab af vidensinstitutioner, NGO’er, interesseorganisationer mm. er der én ting, som der har været bred enighed om: På det marine område har der været behov for at forbedre det faglige grundlag frem mod anden generation af vandplaner. Nu kommer så anden generation af vandplaner. Anden generation af vandplaner skal efter planen sendes i høringen med udgangen af december 2014, og skal, når den er endeligt vedtaget, gælde for perioden 2015-2021. Fra første generation til anden generation af vandplaner har der været arbejdet intenst med at forbedre og videreudvikle det marin-faglige grundlag. På baggrund af anbefalinger fra Ålegræs Gruppe I+II og anbefalingerne fra Natur & Landbrugskommissionen er der derfor udviklet en række lokalspecifikke marine modelværktøjer. Disse værktøjer omfatter både statistiske og mekanistiske modeller, og de er blevet anvendt til vurdering af vandområdernes tilstand og indsatsbehov. Modelarbejdet har fokuseret på at få inddraget flere miljøkvalitetsparametre og få udviklet lokalspecifikke modeller for så mange vandområder som muligt, og i dag foreligger der specifikke modeller for godt 90% af det samlede vandområde areal.