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Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,CONICET | Gutierrez J.L.,Cary Institute of Ecosystem Studies | Jones C.G.,Cary Institute of Ecosystem Studies | And 2 more authors.
Acta Oecologica | Year: 2014

Progress in the study of ecosystem impacts of invasive species can be facilitated by moving from the evaluation of invasive species impacts on particular processes to the analysis of their overall effects on ecosystem functioning. Here we propose an integrative ecosystem-based approach to the analysis of invasive species impacts that is based on an understanding of the general mechanistic links between biotic factors, abiotic factors, and processes in ecosystems. Two general kinds of biotic mediation - direct and indirect - and two general mechanisms of invasive species impact - assimilatory-dissimilatory (uptake and release of energy and materials) and physical ecosystem engineering (physical environmental modification by organisms) - are most relevant. By combining the biotic mediation pathways and the general mechanisms, four general situations emerge that characterize a great many of the impacts invasive species can have on ecosystem processes. We propose ways to integrate these distinctive impacts into general mechanistic representations that link ecosystem processes with changes in biotic and abiotic states (changes in structure, composition, amount, process rates, etc.). In turn, these help generate predictions about the interplay of invasive species and other drivers of ecosystem processes that are of particular relevance to ecosystems where invasive species co-occur with other anthropogenic impacts. © 2013 Elsevier Masson SAS.


Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,CONICET | Gutierrez J.L.,Cary Institute of Ecosystem Studies | Palomo M.G.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | And 4 more authors.
Marine Ecology Progress Series | Year: 2015

Intraspecific competition for space is generally invoked as the chief process limiting crowding in sessile or highly sedentary marine invertebrates. However, the mechanisms by which high conspecific density induces individual removal or mortality, in turn restraining crowding in these organisms, generally remain uninvestigated. Here we illustrate that mussel crowding in a southwestern Atlantic rocky intertidal shore is limited by a combination of wave action and space limitation. Brachidontes rodriguezii mussel beds at this site occur primarily as a single layer of individuals because wave forces remove multilayered mussel hummocks quickly after they develop. Mussels in hummocks show lower attachment strength than those in the single-layered matrix. Accordingly, wave conditions associated with the passage of cold fronts (i.e. transition zones from warm air to cold air accompanied by moderate to strong winds and wave action, with 7 d average recurrence times based on historical weather data) cause detectable mussel dislodgment in a high proportion of hummocks but have virtually no impact on single-layered areas. Since wave action is the proximate cause of mussel dislodgment, upper limits to crowding in this species would not be fixed to a particular level of space occupation (i.e. as predictable from interindividual interference alone) but would be variable in space and time depending on wave exposure. This example suggests a mechanism of population control where the impact of a physical factor on population size is larger at higher population density and supports early hypotheses about the occurrence of density-dependent population control by physical factors when the availability of safe sites is limiting. © Inter-Research 2015.


Palomo M.G.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Palomo M.G.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Bagur M.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Quiroga M.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | And 2 more authors.
Marine Biology | Year: 2016

Non-indigenous marine species often change the abundance and diversity of native species in coastal ecosystems. On the SW Atlantic coast, the macroalgae Ahnfeltiopsis sp. (Rhodophyta, Phyllophoraceae) and Schizymenia dubyi (Rhodophyta, Schizymeniaceae) have invaded the intertidal rocky shore of Mar del Plata, Argentina (38°S, 57°W). To study the spread and ecological associations of these invasive species, algal abundance, biomass and biodiversity of benthic assemblages at three different tidal levels were examined during five years. Sparse Ahnfeltiopsis sp. thalli (3 % cover) were detected in February 2007 at the three tidal levels. By January 2011, its cover had increased to 11 %, while its biomass showed a 27-fold increase. S. dubyi was detected at the lower intertidal level in January 2010 with a cover of 2 %. By January 2011, it had increased to 5 % and spread to the other intertidal levels. The presence of these two non-indigenous algae modified the substrate and the structure and composition of the benthic assemblage. The constant increase in the algal biomass and presence along the intertidal suggest that the effect will be greater in the future. Moreover, the effects of these exotic algae could potentially displace Brachidontes rodriguezii—an important ecosystem engineer that creates microhabitat for a large number of organisms on these shores. © 2016, Springer-Verlag Berlin Heidelberg.


Bagur M.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,CONICET | Arribas L.P.,CONICET | Palomo M.G.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia
Biodiversity and Conservation | Year: 2016

Structural modification of the environment by physical ecosystem engineers often allows for the occurrence of species that are not able to establish in unengineered habitats, thus leading to increased species richness at the landscape-level (i.e., areas encompassing engineered and unengineered habitats). Unlike previous studies that focused on the contribution of a single engineering species to landscape-level species richness, this study evaluates whether co-occurring engineers—i.e., intertidal mussels (primarily Perumytilus purpuratus) and rock boring bivalves (Lithophaga patagonica)—contribute to landscape-level species richness in a similar or complementary way. Our results show that both mussel and L. patagonica patches harbor a substantial number of invertebrate species in addition to those occurring in the unenegineered rock substrate. However, the distinctive habitat patches created by each engineer add exclusive subsets of species to the study area, which implies that mussel and L. patagonica patches contribute complementarily to overall species richness in our intertidal landscape. Here we postulate that complementary engineering effects on landscape-level species richness will occur when the engineered patches structurally differ from each other and, thus, vary in their relative ability to modulate two or more abiotic conditions and/or resources that prevent species establishment in the unengineered state. In spite of its inherently small spatial scale (500 m), our study highlights the potential for complementary engineering impacts at the larger scales that are usually implied in biodiversity conservation and management (tens to hundreds of kilometers) and outlines a simple conceptual basis and approach to address them. © 2016 Springer Science+Business Media Dordrecht


Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,CONICET | Gutierrez J.L.,Cary Institute of Ecosystem Studies | Palomo M.G.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Palomo M.G.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia
Journal of Sea Research | Year: 2016

If the external surfaces of epibionts are more suitable to other fouling species than those of their basibionts, a 'fouling cascade' might occur where epibionts facilitate secondary colonization by other epibionts. Here we evaluate whether the presence of epibiotic barnalces (Balanus glandula) influences the probability of mussel (Brachidontes rodriguezii) fouling by ephemeral red algae (Porphyra sp.) in a Southwestern Atlantic rocky shore. Mussels with barnacle epibionts showed a higher prevalence of Porphyra sp. fouling (32-40% depending on sampling date) than mussels without them (3-7%). Two lines of evidence indicate that barnacles facilitate Porphyra sp. fouling. First, most Porphyra sp. thalli in mussels with barnacle epibionts were attached to barnacle shells (75-92% of cases). Secondly, Porphyra sp. associated with mussels with barnacle epibionts in a proportion that significantly exceeded that expected under random co-occurrence. These results suggest the occurrence of a fouling cascade where barnacle epibiosis on mussels facilitates subsequent algal fouling. Recognizing the occurrence of such fouling cascades is important because they might explain the non-random aggregation of multiple epibiotic species onto a proportionally few individuals of the host species. © 2016 Elsevier B.V..


Bagur M.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,CONICET | Gutierrez J.L.,Cary Institute of Ecosystem Studies | And 2 more authors.
Marine Biology | Year: 2014

Organisms boring into intertidal consolidated sediments generate bioerosion. It is generally unknown, however, whether they can significantly contribute to coastline retraction. In this paper, we describe endolithic communities and estimate bioerosion and physical erosion rates at three southwestern Atlantic intertidal sites (37, 38, and 42°S; Argentina). In the northernmost site, we have also analyzed spatial variation in species richness and abundance as a function of height within the tidal slope, orientation of the rock surface in relation to breaking waves (i.e., facing or not), and rock hardness. The number of species and the combined abundance of individuals from the different species were larger at the low intertidal level but did not differ between surface orientations. The density of chemically boring organisms increased with increasing rock hardness and calcium carbonate content. In contrast, no correlation was found between rock hardness and the abundance of organisms that bore by mechanical means. Endolithic community composition and bioerosion rates differed among the three sites, the latter being higher at the site with the softer substrate. Bioerosion estimates were two orders of magnitude lower than physical erosion estimates at each site. The bivalve Lithophaga patagonica was the species that contributed the most to bioerosion at all these locations. While results suggest that bioerosion contributes little to overall coastal erosion at the three study sites, boring organisms might still facilitate physical erosion by weakening the rock either via chemical or mechanical means. Besides, their apparently inconsequential direct action as bioeroders can have positive consequences for biodiversity via increased habitat complexity. © 2014, Springer-Verlag Berlin Heidelberg.


Jones C.G.,Cary Institute of Ecosystem Studies | Jones C.G.,Agro ParisTech | Gutierrez J.L.,Grupo de Investigacion y Educacion en Temas Ambientales GrIETA | Gutierrez J.L.,University of the Sea | And 4 more authors.
Oikos | Year: 2010

While well-recognized as an important kind of ecological interaction, physical ecosystem engineering by organisms is diverse with varied consequences, presenting challenges for developing and using general understanding. There is also still some uncertainty as to what it is, and some skepticism that the diversity of engineering and its effects is amenable to conceptual integration and general understanding. What then, are the key cause/effect relationships and what underlies them? Here we develop, enrich and extend our extant understanding of physical ecosystem engineering into an integrated framework that exposes the essential cause/effect relationships, their underpinnings, and the interconnections that need to be understood to explain or predict engineering effects. The framework has four cause/effect relationships linking four components: 1. An engineer causes structural change; 2. Structural change causes abiotic change; 3. Structural and abiotic change cause biotic change; 4. Structural, abiotic and biotic change can feedback to the engineer. The first two relationships describe an ecosystem engineering process and abiotic dynamics, while the second two describe biotic consequence for other species and the engineer. The four relationships can be parameterized and linked using time-indexed equations that describe engineered system dynamics. After describing the relationships we discuss the utility of the framework; how it might be enriched; and briefly how it can be used to identify intersections of ecosystem engineering with fields outside ecology. © 2010 The Authors.

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