Patchy sediment contamination scenario and the habitat selection by an estuarine mudsnail

Abstract

Since mudsnails are able to avoid contaminated sediment and that the contaminants in sediment are not uniformly distributed, the mudsnail Peringia ulvae was exposed to cadmium (Cd) spiked sediment and assessed for avoidance response in a heterogeneous contamination scenario. Four Cd concentrations were prepared and disposed in patches on dishes, which were divided in 25 fields (six fields for each sediment concentration); 24 organisms were deployed in the central field, with no sediment. Observations were made at 2, 4 and 6 h (corresponding to immediate response), 8, 10 and 12 h (very short term), and 24 h (short term). A trend to avoid contaminated patches was observed in the immediate and very short term. After 24 h exposure, the organisms exposed to the highest level of contamination seemed to have lost the ability to move and avoid contaminated patches. In a contamination scenario in which non- and contaminated sediment patches are heterogeneously distributed, local mudsnail populations can simply rearrange their locality without needing to move to a different habitat. Such less contaminated patches can become donor areas in a future recolonization scenario.

Not Only Toxic but Repellent: What Can Organisms’ Responses Tell Us about Contamination and What Are the Ecological Consequences When They Flee from an Environment?

“…These authors observed that among the different lineages tested, the sensitivity and early reactiveness of the organisms to avoid copper was directly related to the lethal sensitivity of the lineages. Other invertebrates such as the cladoceran D. magna (exposed to pulp mill effluents [53]; atrazine [51]; and salinity as stress factor [54]), the freshwater copepod Boeckella occidentalis intermedia (crude oil as the contaminant [55]), the ostracod Heterocypris incongruens (salinity as the stress factor [54]), the gastropod Peringia ulvae (sediment spiked with cadmium [56]), the freshwater shrimp Atyaephyra desmarestii (exposure to copper [39,[57][58][59]), the marine shrimp Litopenaeus vannamei (exposed to copper [60,61]), and the saltmarsh shrimp Palaemon varians (exposed to musks and sunscreens [25,62]) have been tested for avoidance. In general, the avoidance response reported in those studies was more sensitive than the lethal and some sub-lethal endpoints described by other authors (see references cited above).…”

Joint Effects of Fragmentation and Mercury Contamination on Marsh Periwinkle (Littoraria irrorata) Movement

“…Deforestation and habitat fragmentation can also enhance soil erosion and leaching of mercury (Hg), becoming an important source of contamination to watersheds and aquatic life (Mainville et al, 2006;Roulet et al, 1999). Contaminants can also potentially act as chemical barriers in ecological systems, reducing the connectivity of the landscape even at lower concentrations (Araújo et al, 2016(Araújo et al, , 2018. For instance, Poecilia reticulata fishes avoided crossing waters contaminated with the herbicide atrazine, which can lead to isolation of populations and habitat fragmentation (Araújo et al, 2018).…”

“…However, contaminants can potentially affect organism movement and dispersion in the landscape. For instance, nonlethal concentrations of different classes of contaminants can affect speed, grazing (Bernot et al, 2005), habitat selection (Araújo et al, 2016; McCloskey & Newman, 1995), path tortuosity (i.e., how straight a path is; Kane et al, 2004), and predator avoidance (Zhou & Weis, 1999). Changes in these behaviors could further reduce animal movement and functional connectivity of the landscape and consequently worsen the effects of fragmentation.…”

Avoidance response by shrimps to a copper gradient: Does high population density prevent avoidance of contamination?

“…However, it has been shown that contaminants can also be hazardous by triggering escape behavior (spatial avoidance) or preventing the preference for a habitat in recolonization processes (Lopes et al 2004;De Lange et al 2006;Rosa et al 2012;Ara ujo et al 2016c). The nonforced exposure approach simulates the different scenarios of spatial distribution of the contaminants that can potentially be observed in the field, either as a contamination gradient or a patchy distribution (Ara ujo et al 2016b). The approach using a nonforced exposure scenario (organisms are not confined to only one concentration/sample, but instead they can choose to stay in different ones) is a way of checking how organisms' displacement and habitat-selection processes are affected by contamination.…”

“…In fact, the use of avoidance and preference in a nonforced exposure system is an alternative and complementary approach in ecotoxicology that has shown its usefulness in contamination-driven habitat-selection studies (Ara ujo et al 2016c. The nonforced exposure approach simulates the different scenarios of spatial distribution of the contaminants that can potentially be observed in the field, either as a contamination gradient or a patchy distribution (Ara ujo et al 2016b). To simulate those scenarios, organisms are simultaneously exposed to different environmental samples or concentrations of toxicants in a free-choice, multicompartmented, nonforced system, allowing them to move toward the most favorable zones (Lopes et al 2004;Moreira-Santos et al 2008).…”