Burrow characteristics, food type, and feeding h a b~t s of the SW Atlantlc burrowing crab Chasmagnathus grdnulata were compared between ~n d i v~d u a l s living in mud flats and In Spartinadominated marshes. Burrows were shorter ( X -19.7 cm, SD = 5 8, n = 54) and more dynamlc (entrance displacement: X = 3 2 cm d-l, SD = 1 7, n = 21) in mud flats than In Spartlna-dominated areas (length X = 41 cm, SD = 12, n = 78, no entrance displacement). Sediment turnover rate was much higher in mudbetween areas, being straight, near-vert~cal tunnels in the vegetated area, but oblique (average angle to vertical = 60'. SD = 16", n = 110), and having a funnel-shape entrance and a much large]-diameter in mud flats Stomach contents also differed between habitats. Pleces of plants dominated contents in the vegetated area, while sediment (with polychaetes, diatoms, ostracods, and nematodes) d o m~n a t e d in the mud flats, lndicatlng that crabs are mainly deposit feeders In the mud flats a n d herb~vorous in the Spart~na-dominated areas. This pattern suggests that the heuristic model relatlng burrow arch~tecture to trophic modes prev~ously proposed for fossorial thalassinidean shrimps applies to individuals of a C granulata populat~on The burrow content showed higher organic content and vegetal parts in the vegetated area than in the other area. Burrows in the mud flat showed a significantly higher abundance of nematodes and ostracods. Due to their hydrodynalnic characteristics and content, burrows in the mud flats may work as passive traps for sediment and organic matter. Given the extensive intertidal area inhabited by C granulata in SW Atlantic estuanes, and the locatlon of their burrows (between marshes and the open estuary), these burrows may work as traps for detritus, thus reduclng the export rate of organic matter from marshes.

Why do ecologists seem to underestimate the consequences of using bad taxonomy? Is it because the consequences of doing so have not been yet scrutinized well enough? Is it because these consequences are irrelevant? In this paper I examine and discuss these questions, focusing on the fact that because ecological works provide baseline information for many other biological disciplines, they play a key role in spreading and magnifying the abundance of a variety of conceptual and methodological errors. Although overlooked and underestimated, this cascade-like process originates from trivial taxonomical problems that affect hypotheses and ideas, but it soon shifts into a profound practical problem affecting our knowledge about nature, as well as the ecosystem structure and functioning and the efficiency of human health care programs. In order to improve the intercommunication among disciplines, I propose a set of specific requirements that peer reviewed journals should request from all authors, and I also advocate for urgent institutional and financial support directed at reinvigorating the formation of scientific collections that integrate taxonomy and ecology.

In this work we evaluated the effect of the burrowing crab Chasmagnathus granulata on the soil quality and on the cordgrass Spartina densiflora in a SW Atlantic coastal lagoon (Argentina, 37'32'S, 57" 19'W). Soil hardness and percolation rates were higher outside the crab inhabited area than inside, and soil profiles showed 2 different strata In areas without crabs. Crabs were associated with low soil water content, a higher variabihty In pH, and a homogeneous distribution of organic matter. Meiofaunal abundance was lower inside the area inhabited by crabs than outside. The water content of aboveground structures of S. densiflora was lower inside the crab populated areas. Leaf survival was lower inside the area inhabited by crabs than outside. In areas with new shoots (after burning by a brush flre) crabs depleted the aboveground plant structures. A caging experiment showed that crabs decreased leaf survival by herbivory. During the experiment, substrata was covered by sediment displaced by crabs, and the area showed less soil hardness and lower percolation rates than controls. Crabs decreased water content and organic matter on upper sediment layers. Meiofaunal abundance (arachnids and insects) was higher in control plots (without crabs) than in treatment plots. A field selection expenment showed that crabs decreased survival of young stems, but did not affect old stems. K11 this evidence suggests that C. granulata affects cordgrass production by herbivory on new shoots, and can change the physical characteristics of the environment, which may also indirectly affect S. densiflora production. Thus, the general belief that in Spartina marshes only a small proportion of primary production is consumed in situ may not apply to SW Atlantic Spartina marshes inhabited by crabs.

Aim  During the last 20 years, the austral cordgrass Spartina densiflora has been recorded aggressively invading estuarine environments in the USA, Spain and Morocco. Whereas this species is one of the three most widely distributed worldwide, it is among the least studied within the genus. The objective of this work is to integrate baseline information about the taxonomy, global distribution, centre of origin, and general ecology of S. densiflora in native and invaded marshes worldwide in order to help to strengthen management efforts currently directed at controlling or eradicating it from locations where it has been introduced. Location  World‐wide. Methods  I review, update and discuss relevant information about S. densiflora published in peer‐reviewed papers, including those in journals with limited international distribution. I also review theses and major technical reports containing critical up‐to‐date information. Results  This work indicates that, although S. densiflora remains in need of thorough scientific attention, key information on its taxonomy, distribution and invasive biology has been overlooked because it was published in languages other than English, and/or in journals with restricted distribution. Main conclusions  Spartina densiflora seems to have originated along the east coast of South America; today, however, many other regions worldwide serve as donors for this invasive species, including Chile, the USA, Spain and Morocco. Spartina densiflora is a bioengineer organism, tolerant of a broad spectrum of environmental conditions and able to re‐shape the structure of invaded communities not just in mudflats, but also on sandy, muddy, and rocky shores as well as on cobble beaches. Only by integrating local‐scale research conducted in different geographical regions will we be able to understand the between‐site variations of its biological cycle, which in turn will aid in the design of more effective conservation strategies.

The aim of this study was to explore the origin of the invasive Spartina densiflora by analysing samples from the native region (South America) and from a recently colonized area (California). A combination of various molecular data (chloroplast and nuclear sequences, molecular fingerprint) and ploidy level estimations was used to answer the question whether the reticulate phylogenetic pattern previously detected in S. densiflora was restricted to California, or alternatively, whether a more ancient hybrid origin preceded formation of this species in its native area. We found that this species is heptaploid in both its native and introduced range. Identification of nuclear homeologous sequences indicate that this species has a reticulate origin in its native range, involving a lineage related to the hexaploid clade formed by S. alterniflora, S.foliosa, and S. maritima, and another lineage related to the sub-Antarctic endemic S. arundinacea that provided the chloroplast genome. The samples from California displayed similar multilocus patterns to the samples from Chile, supporting the hypothesis that this species originated on the southeast American coast (Argentina), from where it eventually spread to the west coast of South America (Chile) first and to the Northern Hemisphere (California) later.