Paula Chainho

Seasonal and spatial patterns of distribution of subtidal benthic invertebrate communities in the Mondego River, Portugal : a poikilohaline estuary

The use of benthic assemblages to assess ecological quality of estuarine environments is a major tool for the implementation of the Water Framework Directive (2000/60/CE) for European aquatic ecosystems. Benthic communities show spatially heterogeneous distributions and experience seasonal variations due to both natural and anthropogenic stresses. The major goal of this study was to quantify the relationships between environmental gradients and the spatial and temporal patterns of the benthic communities along a Portuguese estuary. Seasonal and spatial variations relating macrobenthic communities and measures of water and sediment quality along the northern branch of the Mondego River estuary were examined at seven sampling stations from July 2000 to June 2001. Cluster analysis of biological data indicated three major groups of communities based on spatial distribution patterns: (1) a lower sector with stronger marine influence and dominated by Streblospio shrubsolii and Cerastoderma glaucum; (2) a middle sector with dominance of S. shrubsolii and Corophium multisetosum; (3) and an upper sector where C. multisetosum dominates a community characterized by a lower number of species. Canonical correspondence analyses of biological and environmental data determined a major salinity gradient influencing benthic communities. Seasonal changes of benthic communities were mainly determined by freshwater input and salinity changes that imposed a strong decrease in densities and number of species during winter, followed by a recovery during spring. Benthic ecological structure and contaminant levels indicated that the Mondego northern branch is moderately disturbed, although opportunistic species dominated the benthic community, suggesting that natural and anthopogenic sources of stress may be acting together. The Mondego River estuary, a poikilohaline-type estuary, characterized by strong seasonal changes in water flow and salinity, cannot be consistently stratified into salinity regions based upon the Venice classi- fication system. Biotic communities, exemplified here by the benthic communities, are seasonally displaced, compared to a homiohaline-type estuary where the Venice system can be applied without modification. Future identification of reference conditions and design of monitoring programs cannot be accomplished without understanding how interactions between biotic and physico-chemical dynamics differ between homiohaline and poikilohaline estuaries. Results obtained in this study could be used to assist future assessments in other Portuguese estuaries.

Use of multimetric indices to classify estuaries with different hydromorphological characteristics and different levels of human pressure.

The assessment of estuaries based on benthic communities is widely used to determine impacts caused by human pressure and is one of the required tools for the implementation of the European Water Framework Directive (WFD). Our study compared multimetric approaches (B-IBI and TICOR) to assess the benthic condition of three Portuguese estuaries (Mondego, Tejo, and Mira rivers) with different levels of natural and human induced stress. Benthic community condition was classified into quality status categories of the WFD and compared for consistency with a priori status categories based upon physical-chemical criteria. Both multimetric indices discriminated equally well between locations classified above or below the good status category but were unable to provide good separation between other quality classes (high/good, moderate, poor/bad). Metrics included in these indices are greatly affected by natural stress and we recommend the development of habitat-specific thresholds to increase the discriminatory ability of any benthic condition index.

Taxonomic sufficiency as a useful tool for typology in a poikilohaline estuary

Taxonomic sufficiency has been used mainly to assess benthic condition, based on the assumption that taxa can be identified to a taxonomic level higher than the species level without losing the ability to detect changes related to pollution stress. Identifying taxa to a higher level reduces the expertise and time needed to identify organisms and consequently allows increased spatial and temporal replication. The usefulness of taxonomic sufficiency for typology (identification of water body types) was examined using the benthic communities of the Mondego River estuary (Portugal). Benthic samples were collected seasonally along the Northern branch of the Mondego River estuary from July 2000 to June 2001 and several environmental parameters were measured simultaneously. Cluster analysis of species data indicated three major ecological groups, mainly related to a saline gradient along the estuary. The same groups were found when taxa were aggregated to higher taxonomic levels (genus, family, order, class), except for the phylum level. The overall spatial pattern was driven by: (1) the dominance of bivalves and the occurrence of rare marine species in the Lower Estuary; (2) the dominance of polychaetes in the Middle Estuary; (3) and the dominance of arthropods in the Upper Estuary. The ability of different taxocenes to discriminate the three ecological groups was also examined. Mollusca and Bivalvia were the only taxocenes producing the same groupings, although other taxocenes (Annelida, Polychaeta, Spionidae, Arthropoda) showed a significant ability to discriminate between all three groups. Compared to using all taxa identified to the lowest possible taxonomic level, our results indicate that for typology (1) several higher taxonomic levels were sufficient (2) while few taxocenes alone were sufficient.

Metals and As content in sediments and Manila clam Ruditapes philippinarum in the Tagus estuary (Portugal): Impacts and risk for human consumption

The Manila clam is emerging as a relevant species for the Portuguese market. The present work was conducted in the Tagus estuary to evaluate 1) the metals and As content in the sediments of the Tagus estuary, especially on those areas subjected to Manila clam harvesting 2) the metals and As content in clams, and the risk associated with their consumption 3) the physiological and biochemical responses of the clam to metals and As contamination, and its possible role as a pollution bioindicator in the estuarine environment. The most contaminated sediments were identified nearby industrial areas, nevertheless clams collected in low contaminated areas showed high metals and As concentrations. The condition index, glycogen content, membrane oxidative damage, biotransformation enzymes and metallothioneins showed consistent responses to metals and As content in clams. Results emphasize the need for the development of a management plan for the species exploitation in the Tagus estuary.

Impact of freshwater inputs on the spatial structure of benthic macroinvertebrate communities in two landlocked coastal lagoons

Landlocked lagoons are naturally stressed environments. They are strongly influenced by freshwater input which not only varies naturally, but which is also impacted by anthropogenic activities. This study investigated the direct influence of freshwater discharges on the distribution patterns and abundance of benthic communities in two neighbouring landlocked coastal lagoons, assessing the whole system and the confluence area of each tributary. Sampling occurred in the wet and dry seasons of 2011 at two distances from freshwater discharge locations. Both lagoons were colonized by species from two different pools, freshwater and marine. Freshwater flow rates had a direct influence on the spatial structure of the benthic communities of brackish-water/freshwater interface areas, where also specific taxa can act as early indicators of freshwater input variations. The intensity of this influence is highly dependent on lagoon size, creating spatial heterogeneity or affecting the entire system. The benthic fauna at the confluence of the tributary that depends almost exclusively on groundwater showed the lowest variability, suggesting that the biogeochemical nature of the groundwater may be a central cause for setting specific ecotones. The results suggest that benthic communities of landlocked coastal lagoons can be highly impacted by flow reduction from freshwater aquifers under drought conditions or water abstraction activities.

The Atlantic blue crab Callinectes sapidus in southern European coastal waters: Distribution, impact and prospective invasion management strategies

The native distribution of the blue crab Callinectes sapidus in the western Atlantic extends from Nova Scotia to Argentina. Introduced to Europe at the beginning of the 20th century, it is currently recorded almost ubiquitously in the Mediterranean and in the Black Sea. An overview of the occurrence, abundance, and ecological impact of the species in southern European waters is provided; additionally, we present a pragmatic assessment of its management scenarios, explicitly considering the dual nature of C. sapidus as both an invasive species and a fishery resource. We emphasise that the ongoing expansion of C. sapidus in the region may represent a stimulating challenge for the identification and implementation of future strategies in the management of invasive crustaceans. The impact of the invader could be converted into an enhancement of the services delivered by southern European coastal ecosystems, while mitigation costs could be transformed into profits for local populations.

Mangrove fish of São Tomé Island (Gulf of Guinea): new occurrences and habitat usage

Mangroves are recognised as important nursery and feeding areas for resident and inshore fish species. However, the importance of West African mangroves to the life cycle of fish communities remains poorly studied. The present study is the first record of fish species in tropical insular mangroves for this region and its aim was to assess habitat usage by fish species. Two mangroves of Sao Tome Island (Praia das Conchas and Malanza) were sampled with a multihabitat approach and using different fishing gear to maximise the diversity of fish species collected. Several environmental parameters were also measured. Both mangroves are nursery and opportunistic feeding grounds for fish species, as well as settlement areas for resident species. The highest number of both juveniles and adults (inshore and residents) was observed at the Malanza mangrove, which is also the largest and has the highest habitat heterogeneity. Four new occurrences were reported for the Sao Tome and Principe area, namely Pomadasys jubelini, Bostrychus africanus, Dalophis cephalopeltis and the introduced species Oreochromis mossambicus.

Factors affecting the distribution of fish communities in the river Mondego and main tributaries

Fish assemblage structure and factors affecting the distribution of fish communities were examined for 23 sites in the River Mondego basin during the summer of 1998. The cyprinids Rutilus macrolepidotus, Barbus bocagei, Chondrostoma polylepis, Rutilus alburnoides, Leuciscus corolitertii and Gobio gobio were the most abundant species among the 25 taxa forming the freshwater fish community. Species richness was generally higher in impoundments and in the watershed downstream from the AçudePonte dam, at Coimbra The anadromous species were restricted to the area downstream from the Açude-Ponte, except for a landlocked population of Alosa alosa in the Aguieira reservoir. ln the river stretches less affected by the construction of dams, the two main factors responsible for the structure of fish communities were the altitude and the distance from the source. R. rnacro/epidotus and R. albumoides were dominant closer to the source, at lower altitudes, whereas L corolitertii dominated in upper reaches. As the distance from the source increases and the altitude decreases, the fish communities become dominated by B. bocagei and C. polylepis,larger fishes that take advantage of the increase in river depth.

Impact of Invasions on Water Quality in Marine and Freshwater Environments

Water quality of marine and freshwater environments, including brackish waters, can be highly impacted by the introduction, establishment, and spread of non-native species. Phytoplankton are among the most common arrivals, with the bloom-forming species, such as toxic freshwater cyanobacteria and marine dinoflagellates, being of particular concern. Their massive population increase may lead to water discolouration, reduced transparency, changes in nutrients cycling, events of anoxia, and release of potent toxins contaminating the food web and drinking water. Top-down control that regulates primary productivity is carried out by filter-feeding organisms. Bivalve mollusks are often the dominant filter feeders in many aquatic systems. The high filtration rates of some non-native bivalves may significantly increase the ecosystem filtration capacity, resulting in drastic changes of phytoplankton biomass and composition. Invasive bivalves also have a marked role removing other suspended particles, which result in increasing water clarity with subsequent growth of submerged vegetation. This apparent benefit may not be innocuous because changes in phytoplankton composition may lead to dominance of toxic algae species. Biomagnification of contaminants filtered from the water column, biofouling, and increase of sedimentation are among other detrimental effects associated with the increase of non-native bivalve populations. In this chapter, the main impacts on water quality raised by non-native phytoplankton and bivalve species are reviewed.

Allochthonous-derived organic matter subsidizes the food sources of estuarine jellyfish

PEDRO MORAIS, ESTER DIAS, JOANA CRUZ, PAULA CHAINHO, MARIA MANUEL ANGÉLICO, JOSÉ LINO COSTA, ANA B. BARBOSA AND MARIA ALEXANDRA TEODÓSIO*  CCMAR–CENTRE OF MARINE SCIENCES, UNIVERSITY OF ALGARVE, CAMPUS DE GAMBELAS, - FARO, PORTUGAL, DEPARTMENT OF ENVIRONMENTAL SCIENCE, POLICY, AND MANAGEMENT, MULFORD HALL, UNIVERSITY OF CALIFORNIA, BERKELEY, BERKELEY, CA , USA, CIIMAR–INTERDISCIPLINARY