Ecological status of seagrass ecosystems: An uncertainty analysis of the meadow classification based on the Posidonia oceanica multivariate index (POMI)

Quantifying the uncertainty associated with monitoring protocols is essential to prevent the misclassification of ecological status and to improve sampling design. We assessed the Posidonia oceanica multivariate index (POMI) bio-monitoring program for its robustness in classifying the ecological status of coastal waters within the Water Framework Directive. We used a 7-year data set covering 30 sites along 500 km of the Catalonian coastline to examine which version of POMI (14 or 9 metrics) maximises precision in classifying the ecological status of meadows. Five factors (zones within a site, sites within a water body, depth, years and surveyors) that potentially generate classification uncertainty were examined in detail. Of these, depth was a major source of uncertainty, while all the remaining spatial and temporal factors displayed low variability. POMI 9 matched POMI 14 in all factors, and could effectively replace it in future monitoring programs.     

Uncertainty analysis along the ecological quality status of water bodies: the response of the Posidonia oceanica multivariate index (POMI) in three Mediterranean regions

Uncertainty analyses allow the identification and quantification of the factors that contribute to the potential misclassification of the ecological status of water bodies, helping to improve the sampling design used in monitoring. Here we used a Posidonia oceanica multivariate index (POMI) bio-monitoring dataset covering a total of 81 sites distributed throughout 28 water bodies from the coast of Catalonia, Balearic Islands and Croatia to determine the levels of uncertainty associated with each region and how they change according to the quality status of water bodies. Overall, variability among sites (meadows) within water bodies was the factor that generated the greatest risk of misclassification among the three regions, within which the Balearic Islands had the lowest uncertainty, followed by Croatia and Catalonia. When water bodies classified in good/high quality were separated from those in moderate/poor status classes, we found that the latter displayed higher levels of uncertainty than the former.     

Angiosperms (seagrass) within the EU water framework directive: a UK perspective

Taxonomic composition, the presence of disturbance-sensitive species and abundance are attributes for monitoring the status of marine angiosperms; a biological quality element required for assessment of environmental condition under the Water Framework Directive (WFD). Their relevance for defining the ecological status of UK water bodies and the establishment of reference conditions for these attributes are described. Founded on quantitative measurements of these attributes, a set of metrics has been developed for monitoring and assessment of the only truly marine angiosperms, seagrass. The proposed metrics are presented and tested against a variety of littoral and sublittoral UK seagrass beds. In combination they express the cumulative response of marine angiosperms to different levels of anthropogenic disturbance.     

Urban seagrass: status of Posidonia oceanica facing the Genoa city waterfront (Italy) and implications for management

A system of five adjacent Posidonia oceanica meadows facing the waterfront of Genoa city (Ligurian Sea, NW Mediterranean) was investigated over different spatial scales (meters-kilometers) using three environmental indices: conservation index (CI), substitution index (SI) and phase-shift index (PSI). CI revealed differences mostly at large spatial scale, distinguishing the poor condition of the meadows closest to Genoa centre and harbour from the comparatively healthy condition of the farthest meadows. SI showed differences mostly at small spatial scale (i.e., within meadows), suggesting the influence of local factors in the re-colonisation of regressed meadows by the seagrass Cymodocea nodosa and/or the invasive alga Caulerpa racemosa. Mapping of PSI showed that the meadows closest to Genoa centre and harbour have undergone a nearly total phase shift and have no real potential for recovery: attempts to re-establish P. oceanica there might be a waste of time and money. On the contrary, the meadows farthest from Genoa centre and harbour showed a comparatively low level of phase shift and could still fully recover given specific management actions.     

Effects of fish farm loadings on seagrass (Posidonia oceanica) distribution, growth and photosynthesis

The spatial extent and timing of the impact of fish farms on the distribution and performance of a Posidonia oceanica meadow were examined in an embayment of the south-eastern coast of Spain (Hornillo Bay, Murcia). Changes in seagrass distribution were determined using available seagrass mapping (from 1988, i.e., before the onset of aquaculture activities and 1998) and by successive sampling in 1994 and 1998. Environmental variables (light attenuation coefficient, water-column dissolved nutrients and organic content of sediments) together with plant performance (shoot biomass, leaf growth rate, photosynthetic activity, carbohydrate reserves, the number of leaves per shoot, epiphyte loads and herbivore pressure) were measured in plants affected by organic discharges, and were compared with those found in reference healthy plants over an annual growth cycle. Since the onset of fish farm activity, 11.29 ha of P. oceanica meadow has been completely lost and 9.86 ha significantly degraded, thus resulting in a total affected area which accounts for about 53% of the former meadow, or 7-fold the fish farming area. Unequal propagation of seagrass die-off or degradation reflects the relevance of local factors such as depth and hydrodynamism on the true extent of fish farm impact. Water transparency decreases and dissolved nutrient and organic content of sediments increases in the vicinity of cages compared to distant reference stations, thus supporting the notion of environmental gradients caused by the organic release from cages, which spreads outwards. Shoot size, leaf growth rate and the number of leaves per shoot in plants close to the fish farm decreased. Moreover, low leaf growth and low rhizome carbohydrate concentration (always relative to that found in an undisturbed area) indicated carbon budget imbalances. Since light reduction in the affected area was only modest (31% of light reaching the sea surface, while at the same depth this figure was 39% at the reference site), and light availability was well above the minimum requirement estimated for this species, neither this factor nor epiphyte overgrowth (epiphyte load was lower in the affected area) seem to explain such carbon imbalances or the observed meadow regression. Alternatively, the high herbivore pressure found in the affected zone suggests that overgrazing is one of the main causes of decreasing shoot sizes and hence of carbon imbalance, reduced growth and shoot mortality. The impact of fish farms on seagrasses, therefore, seems to be highly variable and depends on complex interactions between a large number of processes.     

Effects of disturbances caused by coastal constructions on spatial structure, growth dynamics and photosynthesis of the seagrass Posidonia oceanica

The light-limitation hypothesis was tested to assess whether water turbidity had caused the decline of a Mediterranean Posidonia oceanica (L.) Delile meadow in an area affected by a harbor. The annual growth, photosynthesis and rhizome starch concentrations of seagrass were measured and related to changes in light availability and dissolved nutrient concentration along a gradient of meadow degradation from areas close to the harbor outwards. Environmental and plant variables were measured in three stations placed along this gradient and compared with a reference station at an undisturbed meadow. The light attenuation coefficient (k) increased toward the inner harbor area, mainly due to sediment resuspension. The shoot density and leaf productivity of P. oceanica shoots were much lower in disturbed stations of the inner harbor area than in the outer, less disturbed station and the reference meadow. However, daily leaf carbon gains, calculated from the photosynthetic rates at saturating irradiance (P_max) and the daily period in which seagrass receives light higher than its saturating irradiance (H_sat), suggested positive C-balance in all stations. This was partly explained by photo-acclimatization of seagrass to the reduced light availability at the disturbed harbor stations (inner and intermediate), as indicated by the lengthening of H_sat and the decrease in saturating irradiance (I_sat) and respiratory demands. Despite photo-acclimatization, disturbed harbor stations showed less positive C-balance, seen not only in their lower leaf growth and biomass but also in a decrease in rhizome carbohydrate reserves (starch). Our results suggest that light reduction account for the reduced seagrass productivity and abundance. However, meadow decline (in terms of shoot mortality) in the harbor area is well above that predicted from similar light environments of nearby meadows or simulated in shading experiments. Thus, there are other factors than light limitation involved in seagrass mortality, most probably through more complex interactions (e.g. nutrient-epiphytes-grazers, water quality––siltation).     

A habitat-specific fish-based approach to assess the ecological status of Mediterranean coastal lagoons

A habitat approach was promoted in the framework of ecological status assessment of transitional waters, assuming the importance of habitat heterogeneity to the overall system status. The approach was applied to the use of fish-based multimetric indices by adapting them to seagrass and marsh habitats in the Venice lagoon, Italy, through selection of appropriate metrics and reference conditions. While for marsh habitats, no clear patterns resulted, the index response for seagrass was consistent with the habitat degradation and loss recorded in the lagoon between 2002 and 2005 and with the higher habitat disturbance in southern and central lagoon sub-basins. The assessment of individual habitats is presented as a first step in the process of evaluating the overall condition of a Mediterranean lagoon environment, which should also take account of the diversity of habitats and their availability within the system to properly define an overall index of ecological status.     

Effects of climate, invasive species and anthropogenic impacts on the growth of the seagrass Posidonia oceanica (L.) Delile in Liguria (NW Mediterranean Sea)

Eight shallow water Posidonia oceanica meadows were sampled in June 1999 along 300 km of the Ligurian coast and were compared through shoot density and lepidochronology. The growth of the seagrass was examined in the light of climate fluctuations and local stresses, colonisation by alien, invasive alga Caulerpa taxifolia, and effects of the oil spill from the tanker "Haven", and other anthropogenic impacts. Both shoot density and lepidochronology pointed to a generalised state of regression of all the meadows. The analysis of long-term growth curves of the rhizomes showed a positive trend parallel to the increase of air temperature. Two main groups of meadows were individuated on the basis of growth curve similarity. The first included four meadows, namely Ventimiglia, Imperia, Noli and Prelo, that were characterised by average values of rhizome growth of 8-9.1 mmyear(-1) and shoot density greater than 200 shootsm(-2). Although the Imperia meadow was the only one where the alien invasive alga C. taxifolia was found, it did not show differences for rhizome growth in comparison to the other meadows. The second group was formed by meadows that had suffered past anthropogenic impacts: Arenzano and Monterosso al Mare. They showed higher rhizome growth rates (9.4-10.6 mmyear(-1)) and shoot densities between 200 and 100 shootsm(-2). At Arenzano, where "Haven" oil was stranded in April 1991, no rhizome older than 8 years was found, thus confirming the shoot mortality induced by the oil spill event. The two last meadows exhibited growth curves very different from all the others: Portovenere, is a shallow meadow where P. oceanica merely survives in an extremely degraded situation with highest rhizome growth rate (12 mmyear(-1)), the other, Riva Trigoso, is the only meadow implanted on rock and had the lowest growth rates (7.1 mm year(-1)).     

Macrophytes and phytobenthos as indicators of ecological status in German lakes — a contribution to the implementation of the water framework directive

A new assessment system for macrophytes and phytobenthos in German lakes according to the Water Framework Directive of the European Community is described. Based on biological, chemical and hydromorphological data from about 100 lake sites covering the main ecoregions, hydromorphological lake types and degradation forms, biocoenotic types could be defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into two components: macrophytes and benthic diatoms. For macrophytes 4 and for benthic diatoms 4 lake types were identified. The benthic vegetation at reference conditions is described and degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For a few of the described lake types further investigations are necessary before a classification can be developed.     

An index to assess hydromorphological quality of Estonian surface waters based on macroinvertebrate taxonomic composition

We developed an index (MESH – Macroinvertebrates in Estonia: Score of Hydromorphology) to assess hydromorphological quality of Estonian surface waters based on macroinvertebrate taxonomic composition. The MESH is an average score based on the affinities of selected indicator taxa to flow velocity and bottom type. As both parameters were highly correlated (r = 0.65) indicator response to both parameters were combined. The list of MESH indicators includes 394 freshwater macroinvertebrate taxa derived from 3282 samples collected from rivers and lakes during 1985–2009. The indicators were selected out of 690 taxa, by applying the information-theoretical Kullback–Leibler divergence. The individual scores of macroinvertebrates range from 0 to 3, the higher scores indicating faster flow and/or solid bottom substrate. For standing waters, flow velocity was always considered zero. Among the reference waterbodies, mean MESH was the highest for small streams followed by middle streams, large streams, and lakes. In lakes with medium water hardness (the prevailing type in Estonia), the MESH decreased gradually from stony to muddy bottom. The highest MESH values for standing waters were observed in the stony surf zone of very large lakes (area > 100 km²). The lowest values occurred for small lakes with exceptional hydrochemical characteristics (soft- and darkwater, and calcareous types). Similarly, MESH indicated stream degradation by damming. Mean MESH in reservoirs with a muddy bottom was significantly lower than in reservoirs with a hard bottom, or in unregulated stream sections.     

Development of a fish-based index to assess the ecological quality of transitional waters: The case of French estuaries

The Water Framework Directive requires the assessment of the ecological status of transitional waters considering the fish component. An original methodology, based on a pressure-impact approach, was established to develop a multimetric fish-based index to characterize the ecological quality of French estuaries. An index of contamination, based on the chemical pollution affecting aquatic systems, was used as a proxy of anthropogenic pressure. The fish metric selection was based on their response to disturbances tested via statistical models (generalized linear models) taking into account sampling strategy and estuarine features. Four metrics, for which discriminating responses to level of pressure were demonstrated, were retained to constitute the estuarine multimetric fish index. This new tool appeared particularly relevant to detect the contamination effects on fish communities in estuaries. It could help managers to take decisions in order to maintain or reach the good status required by the Water Framework Directive for 2015.     

Implementation of the European water framework directive from the Basque country (northern Spain): a methodological approach

The European Water Framework Directive provides a challenge in the development of new and accurate methodologies. It addresses assessment of Ecological Quality Status within European rivers, lakes, groundwaters, estuaries and coasts. Although this directive is simple and flexible in its concept, it is necessary to develop an approach based upon scientific knowledge; however, at the same time it should be as simple as possible, in order to achieve both requirements and comparability of results throughout European waters. This contribution presents the first methodological approach to the problem, as used for estuaries and coasts of the Basque Country (northern Spain), in: selecting typologies and reference conditions; determining biological quality and ecological status; and identifying some problems in implementing the WFD. As such, the present paper could serve as the basis for a discussion document for other regions and countries, throughout Europe.     

Evaluation for the ecological quality status of coastal waters in East China Sea using fuzzy integrated assessment method

This research presented an evaluation for the ecological quality status (EcoQS) of three semi-enclosed coastal areas using fuzzy integrated assessment method (FIAM). With this method, the hierarchy structure was clarified by an index system of 11 indicators selected from biotic elements and physicochemical elements, and the weight vector of index system was calculated with Delphi-Analytic Hierarchy Process (AHP) procedure. Then, the FIAM was used to achieve an EcoQS assessment. As a result of assessment, most of the sampling stations demonstrated a clear gradient in EcoQS, ranging from high to poor status. Among the four statuses, high and good, owning a ratio of 55.9% and 26.5%, respectively, were two dominant statuses for three bays, especially for Sansha Bay and Luoyuan Bay. The assessment results were found consistent with the pressure information and parameters obtained at most stations. In addition, the sources of uncertainty in classification of EcoQS were also discussed.     

Do the Austrian blackfly fauna (Diptera: Simuliidae) support the typological approach of the EU water framework directive?

The Austrian blackfly fauna were analysed with regard to spatial (ecoregions, bioregions), vertical (altitude classes) and longitudinal zonation characteristics [stream order, biocoenotic (= fish) regions] on the basis of 2600 investigation sites. Of a total of 45 species recorded, Simulium ornatum, S. variegatum, S. argyreatum and S. reptans are the most common and most frequently distributed species, occurring in 60% of the investigated sites. Although the Austrian blackfly fauna seem to be quite well documented (on average one investigation site per 32 km²) the jackknife analyses indicates that there are still some fauna deficits. Whereas the species diversity of the main ecoregions is quite similar, the number of species differs clearly between the bioregions. Within the typological context of the Water Framework Directive, the Austrian Simuliidae confirm the bioregions as the most useful spatial units for river typology. A further optimisation in predicting a target list of blackfly species of a site can be achieved by subdividing the bioregions into either catchment area and altitude classes or into longitudinal zonation types (biocoenotic regions).     

Ecological classification of macrophytes and phytobenthos for rivers in Germany according to the water framework directive

A new assessment system for macrophytes and phytobenthos in German rivers meeting the requirements of the Water Framework Directive (WFD) of the European Community is described. Biocoenotic types based on biological, chemical and hydromorphological data from over 200 river sites covering the main ecoregions, hydromorphological stream types and degradation forms have been defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into three components: macrophytes, benthic diatoms and remaining phytobenthos. For macrophytes seven types including one subtype, for benthic diatoms 14 types including three subtypes and for the remaining phytobenthos five river types were identified. The benthic vegetation at reference condition was described for most of the river types. Degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For some of the described river types additional investigations are necessary before a classification system can be developed.     

Ensemble numerical forecasts of the sporadic Kuroshio water intrusion (kyucho) into shelf and coastal waters

The finite volume coastal ocean model downscaling ocean reanalysis and forecast data provided by the Japan Coastal Ocean Predictability Experiment (JCOPE2) are used to forecast sudden Kuroshio water intrusion events (kyucho) induced by frontal waves amplified south of the Bungo Channel in 2010. Two-month hindcast computations give initial conditions of the following 3-month forecasts computations which consist of ten ensemble members. The temperature time series computed by these ten members are averaged to compare with that actually observed in the Bungo Channel, where sudden temperature rises related to kyucho events are remarkable in February, August, and September. Overall, the intense kyucho events actually observed in these months are predicted successfully. However, intense kyucho events are forecasted frequently during the period of May through June even though intense kyucho events are absent during this period in the actual ocean. It is suggested that the present downscaling forecast model requires reliable lateral boundary conditions provided by JCOPE2 data to which numerous Argo data are assimilated to enhance the accuracy. In addition, it seems likely that the model accuracy is reduced by small eddies moving along the shelf break.     

Biomonitoring of metals under the water framework directive: Detecting temporal trends and abrupt changes,in relation to the removal of pollution sources

Temporal trends in metal concentrations, i.e. Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn, measured in soft tissues of Mytilus galloprovincialis mussels and Crassostrea gigas oysters collected from estuarine waters within the Basque Country (Bay of Biscay), have been investigated to determine if actions undertaken have improved the environmental quality of rivers and estuaries. Data compiled between 1990 and 2010 have been analysed statistically, applying the Mann–Kendall and the Mann–Whitney–Wilcoxon tests. Moreover, in those cases with significant trends, the Kolmogorov–Zurbenko Adaptive (KZA) filter was applied to detect abrupt changes. Results showed significant decreasing trends for some metals, i.e. Ni, Cu, Pb and Zn, and differences between medians. Trend lines showed abrupt changes occurring between 1998 and 2002. Therefore, observed downward trends were related to increased wastewater treatment and diversions of discharges to ocean, implemented mainly during 2000–2002.     

Surface water deficiency zoning of China based on surface water deficit index (SWDI)

China’s economic and social development is severely restricted by regional water deficiency, and the determination of water deficiency level in different regions is an important basis of water resource management. In this study, we zoned 32 provinces of China into five surface water deficiency levels based on surface water deficit index derived from the Chinese meteorological satellite FY-2C images. The result shows that China is facing serious water shortage crisis with only 15.44% of total area without water deficiency, which is located in the south and southeast coast. More than 60% of total area of China suffered from severe or extremely water deficiency, which are mainly distributed in western and northern regions. Jingjinji area (namely Beijing, Tianjin and Hebei province), which is a special region with high amount of gross domestic product and relative abundant water resources, is suffering from severe water deficiency. It revealed that water resources were interacted with regional development and water management should consider local conditions. To Jingjinji area, water management should focus on adjustment of industrial structure, urban expansion control and scientific water resources allocation. In general, the surface water deficit index based water deficiency zoning will be of significant value to be applied in water resources management at regional scales.