Ecological quality assessment of transitional waters based on fish assemblages in Portuguese estuaries: The Estuarine Fish Assessment Index (EFAI)

The assessment of water quality has changed markedly worldwide over the last years, especially in Europe due to the implementation of the Water Framework Directive. Fish was considered a key-element in this context and several fish-based multi-metric indices have been proposed. In this study, we propose a multi-metric index, the Estuarine Fish Assessment Index (EFAI), developed for Portuguese estuaries, designed for the overall assessment of transitional waters, which could also be applied at the water body level within an estuary. The EFAI integrates seven metrics: species richness, percentage of marine migrants, number of species and abundance of estuarine resident species, number of species and abundance of piscivorous species, status of diadromous species, status of introduced species and status of disturbance sensitive species. Fish sampling surveys were conducted in 2006, 2009 and 2010, using beam trawl, in 13 estuarine systems along the Portuguese coast. Most of the metrics presented a high variability among the transitional systems surveyed. According to the EFAI values, Portuguese estuaries presented a "Good" water quality status (except the Douro in a particular year). The assessments in different years were generally concordant, with a few exceptions. The relationship between the EFAI and the Anthropogenic Pressure Index (API) was not significant, but a negative and significant correlation was registered between the EFAI and the expert judgement pressure index, at both estuary and water body level. The ordination analysis performed to evaluate similarities among North-East Atlantic Geographical Intercalibration Group (NEAGIG) fish-based indices put in evidence four main groups: the French index, since it is substantially different from all the other indices (uses only four metrics based on densities); indices from Ireland, United Kingdom and Spain (Asturias and Cantabria); the Dutch and German indices; and the indices of Belgium. Portugal and Spain (Basque country). The need for detailed studies, including comparative approaches, on several aspects of these assessment tools, especially in what regards their response to anthropogenic pressures was stressed. (C) 2011 Elsevier Ltd. All rights reserved.

Benthic nematodes biodiversity patterns along the gradient of the Tagus estuary (Western Coast of Portugal): Link with abundances distribution pattern of the nonindigenous bivalve Ruditapes philippinarum

The non-indigenous bivalve Ruditapes philippinarum is native to the western Pacific Ocean and it has been one of the most widely introduced species for aquaculture purposes in Europe. In Portugal its presence is known in several estuaries for more than two decades and its populations have increased greatly along the last years1. Currently it’s one of the dominant benthic species in some areas of the Tagus estuary (264,1±470,8 ind./30s tow). Studies on the impacts of invasive bivalves on meiofaunal communities are scarce and restricted to the harvesting effect. Meiofauna of the Tagus estuary is poorly known and possible impacts of the introduction of R. philippinarum were never assessed.

Unravelling the mechanisms behind the invasion of an introduced and now undesirable grass species

The introduction of Eragrostis curvula (African Lovegrass, herafter Lovegrass) for pasture improvement across Australia has not been successful. Instead Lovegrass, a C4 perennial grass originating from Southern African, has proven unpalatable to stock and to have low nutritional value if stocks do eat it. It has spread prolifically along roadsides, stream banks, conservation areas and pastures. Because control efforts have not been effective, our aim was to determine the putative mechanisms responsible for the dominance of Lovegrass, specifically disturbance (selective grazing) and competition.

Impacts of introduced aquaculture species on markets for native marine aquaculture products : the case of edible oysters in Australia

Economic competition between introduced and native aquaculture species is of interest for industry stakeholders since increased production can affect price formation if both aquaculture species are part of the same market or even substitutes. In this study, we focus on the Australian edible oyster industry, which is dominated by two major species—the native Sydney rock oyster (grown mainly in Queensland and New South Wales) and the non-native Pacific oyster (grown mainly in South Australia and Tasmania). We examine the integration of the Australian oyster market to determine if there exists a single or several markets. Short- and long-run own, cross-price and income flexibilities of demand are estimated for both species using an inverse demand system of equations. The results suggest that the markets for the two species are integrated. We found evidence that the development of the Pacific oyster industry has had an adverse impact on Sydney rock oyster prices. However, our results show that both species are not perfect substitutes. Demand for Sydney rock oysters is relatively inelastic in the long run, yet no long-run relationships can be identified for Pacific oysters, reflecting the developing nature of this sector.

Relative host plant species use by the lantana biological control agent Aconophora compressa (Membracidae) across its native and introduced ranges

Aconophora compressa Walker (Hemiptera: Membracidae) was released in 1995 against the weed lantana in Australia, and is now found on multiple host plant species. The intensity and regularity at which A. compressa uses different host species was quantified in its introduced Australian range and also its native Mexican range. In Australia, host plants fell into three statistically defined categories, as indicated by the relative rates and intensities at which they were used in the field. Fiddlewood (Citharexylum spinosum L.: Verbenaceae) was used much more regularly and at higher densities than any other host sampled, and alone made up the first group. The second group, lantana (Lantana camara L.: Verbenaceae; pink variety) and geisha girl (Duranta erecta L.: Verbenaceae), were used less regularly and at much lower densities than fiddlewood. The third group, Sheena’s gold (another variety of D. erecta), jacaranda (Jacaranda mimosifolia D. Don: Bignoniaceae) and myoporum (Myoporum acuminatum R. Br.: Myoporaceae), were used infrequently and at even lower densities. In Mexico, the insect was found at relatively low densities on all hosts relative to those in Australia. Densities were highest on L. urticifolia, D. erecta and Tecoma stans (L.) Juss. ex Kunth (Bignoniaceae), which were used at similar rates to one another. It was found also on a few other verbenaceous and non-verbenaceous host species but at even lower densities. The relative rate at which Citharexylum spp. and L. urticifolia were used could not be assessed in Mexico because A. compressa was found on only one plant of each species in areas where these host species co-occurred. The low rate at which A. compressa occurred on fiddlewood in Mexico is likely to be an artefact of the short-term nature of the surveys or differences in the suites of Citharexylum and Lantana species available there. These results provide further incentive to insist on structured and quantified surveys of non-target host use in the native range of potential biological control agents prior to host testing studies in quarantine.

Diet composition and prey selection of the introduced grouper species peacock hind (Cephalopholis argus) in Hawaii

The introduced grouper species peacock hind (Cephalopholis argus), was the dominant large-body piscivore on the Main Hawaiian Island (MHI) reefs assessed by underwater visual surveys in this study. However, published data on C. argus feeding ecology are scarce, and the role of this species in Hawaiian reef ecosystems is presently not well understood. Here we provide the first comprehensive assessment of the diet composition, prey electivity (dietary importance of prey taxa compared to their availability on reefs), and size selectivity (prey sizes in the diet compared to sizes on reefs) of this important predator in the MHI. Diet consisted 97.7% of fishes and was characterized by a wide taxonomic breadth. Surprisingly, feeding was not opportunistic, as indicated by a strongly divergent electivity for different prey fishes. In addition, whereas some families of large-body species were represented in the diet exclusively by recruit-size individuals (e.g., Aulostomidae), several families of smaller-body species were also represented by juveniles or adults (e.g., Chaetodontidae). Both the strength and mechanisms of the effects of C. argus predation are therefore likely to differ among prey families. This study provides the basis for a quantitative estimate of prey consumption by C. argus, which would further increase understanding of impacts of this species on native fishes in Hawaii.

Deleterious effects of non-native species introduced into Lake Victoria, East Africa

Lake Victoria, in East Africa, has suffered from introductions and invasions of non-native species such as Lates niloticus, various tilapiine species, and Eichornia crassipes since the 1950s. These have had a devastating effect on the natural biological communities. This paper reviews the effects of the introductions on ecology, environment, fisheries and the local human population.

Effects of environment and an introduced invertebrate species on the structure of benthic macroinvertebrate species at the catchment level

Biotic interactions such as predation and competition can influence aquatic communities at small spatial scales, but they are expected to be overridden by environmental factors at large scales. The continuing threat to freshwater biodiversity of biological invasions indicates that biotic factors do, however, have important structuring roles. In Irish rivers, the native amphipod Gammarus duebeni celticus has become locally extinct, ostensibly through differential predation by the more aggressive and introduced G. pulex. This mechanism explains impacts of G. pulex at within-river spatial scales on native macroinvertebrate community diversity, including declines in ephemeropterans, plecopterans, dipterans and oligochaetes. To determine if these patterns are predictable at larger spatial scales, we assessed patterns in native macroinvertebrate communities across river sites of the Erne catchment in 1998 and 1999, in conjunction with the distribution of G. pulex and G. d. celticus. In both years, G. pulex dominated invaded sites, whereas G. d. celticus occurred at low abundance in uninvaded sites. In both years, invaded sites had lower diversity and fewer pollution sensitive invertebrate species than un-invaded sites. Community ordination in 1998 showed that invaded sites had higher conductivity, smaller substrate particle size and comprised a lower proportion of pollution sensitive taxa including Ephemeroptera and Plecoptera. In contrast, in 1999, conductivity was the only variable explaining site ordination along axis 1, but was unable to separate sites with respect to invasion status. A second explanatory axis separated sites with respect to invasion status, with invaded sites having fewer taxa, including lower abundance of ephemeropterans, dipterans and plecopterans. Laboratory experiments examined the potential role of differential predation between the two Gammarus species in explaining these taxon specific patterns in the field. Survival of the ephemeropterans, Ephemerella ignita and Ecdyonurus venosus and the isopod, Asellus aquaticus, was lower when interacting with G. pulex than with G. d. celticus. This study indicates that G. putex may alter invertebrate community structure at scales beyond those detected within individual rivers. However, effects may be influenced by gradients in physico-chemistry, which may be temporal or depend on catchment characteristics. Invasions by amphipods have increased globally, thus comprehensive assessments of their impacts and of other aquatic invaders, may only be apparent when studies are conducted at a range of spatio-temporal scales.

Occurrence of Atta laevigata (Hymenoptera: Formicidae) in the South of Espirito Santo State, Brazil. Recently Introduced or Endangered Species?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

SEASONAL SPACE USAGE BY THE INTRODUCED PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE), IN INSTITUTIONAL SETTINGS IN BRAZIL AND ITS RELATION TO OTHER STRUCTURAL ANT SPECIES

In an institutional setting in Brazil, the pharaoh's ant, Monomorium pharaonis was found to be the dominant and most abundant ant present throughout the year. The only other regularly collected ant was the exotic Tapinoma melanocephalum. However, M. pharaonis dominated bait station visitations, although locally concentrated, with other species restricted to regions in which M. pharaonis was not found.