Interactions of components of habitats alter composition and variability of assemblages (original) (raw)
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Austral Ecology, 2010
A fundamental problem in ecology, regardless of habitat or system, is understanding the relationship between habitats and assemblage of organisms. It is commonly accepted that differences in composition and surrounding landscape of habitats affect the diversity of assemblages, although there is not much empirical evidence because of difficulties of manipulating structure in many habitats. These relationships were examined experimentally, using habitats of artificial turfs that are colonized by diverse assemblages of gastropods. Each habitat was made of nine sub-habitats, which were sampled individually to allow tests of hypotheses about the effect of type of habitat and the influence of other adjacent sub-habitats on the colonizing assemblage. Turf habitats were deployed for 8 weeks on a rocky shore after which they were collected and the colonizing assemblages of gastropods sampled. Independently of the types of turfs combined to form different habitats, there were more species where there was more than one type of component in a habitat (i.e. structural diversity).The type of habitat (i.e. structural identity) itself had little or no influence on the colonizing assemblage. The number of species colonizing short-sparse and short-dense turfs was influenced by which type of habitat was adjacent. Thus, when units of one type (e.g. short-sparse turf) were added to a patch of habitat of long-sparse turfs, the number of species in short-sparse turfs was greater than in patches of the same type.This also increased total number of taxa in the whole patch of habitat. These results show how diversity of gastropods colonizing heterogeneous patches of habitat is influenced not only by the number of types of sub-habitats, but also by interactions with surrounding sub-habitats. These findings reiterate the importance of investigating the role of structure of habitats and of their surrounding landscapes across different systems, irrespective of their size or associated assemblages of organisms.
Water
We aimed to determine the effects of water level and habitat heterogeneity on gastropod fauna in the littoral zone, and the differentiation of functional feeding guilds (FFG) of gastropods. Two periods were analyzed: 2012 (low water level, LWL) and 2013 (high water level, HWL) in the littoral zone of two shallow waterbodies (Sutla backwater, NW Croatia). Waterbody S1, covered with Ceratophyllum demersum, was sampled in the macrophyte stands, and the littoral benthal area, while waterbody S2, without macrophytes, was sampled only in the littoral benthal area. It was observed discovered that among the macrophyte stands in S1, gastropods were significantly more abundant during LWL. The same trend was observed in the littoral benthal area of S2. In contrast, gastropod abundance was higher in the littoral benthal area of S1 during HWL. Comparing gastropods in the two waterbodies, the abundance in S1 was ten times higher than in S2. The most abundant species was Gyraulus parvus, which acc...
Restoration Ecology, 2004
We investigated the assumption that populations of epibenthic macroinvertebrates readily establish in created coastal wetlands by quantifying the spatial and temporal patterns of Cerithidea californica (California horn snail) density in a newly created wetland and an adjacent natural area in Mugu Lagoon, southern California, United States, for 3.5 years. The natural and created sites differed in vascular plant cover and sediment grain size, organic content, salinity, and moisture content. Densities of C. californica in the created site changed little during the study period, and were often lower than those in the natural site. The influences of habitat suitability and dispersal limitation on C. californica colonization of the created site varied among snail age classes. Sediment moisture and organic content explained some of the variability in subadult (47%) and adult (55%) density and relative abundance, but none of the variability in juvenile abundance. Adult snail density was also strongly influenced by distance from the natural/created site transition zone. Juvenile and subadult snail densities were not related to distance from the natural site, possibly due to greater dispersal ability. Between-site differences in C. californica densities and size structure suggested that adult snails were affected by both habitat characteristics and dispersal ability, subadults were influenced to a lesser degree by habitat characteristics, and juveniles were not related to either factor. Accordingly, the influence of habitat characteristics and dispersal ability on created site colonization may change with snail age. Successful restoration of benthic invertebrate communities requires consideration of both habitat characteristics and dispersal ability of the target species, even in created sites in close proximity to natural areas.
Intertidal coarse woody debris: A spatial subsidy as shelter or feeding habitat for gastropods?
Estuarine, Coastal and …, 2006
Coarse woody debris (CWD) in the intertidal region of rocky shores serves as a potential source of nutrients as well as habitat or refugia from predation, ecologically linking the adjacent marine and terrestrial habitats. In a series of field and laboratory experiments, the affinity of slow-moving motile intertidal gastropods to CWD either as food source or as shelter that increases habitat complexity was tested. In intertidal pools, CWD did not increase colonization by Littorina spp., while it did so in supratidal pools. Habitat complexity, brought about by algal cover and barnacles, was apparently sufficient in intertidal pools without woody debris, while the increase in habitat complexity by CWD increased the attractiveness of supratidal pools with little natural complexity to Littorina spp. Overall, however, comparison of pools containing woody debris and those containing artificial shelter provided evidence for CWD, and/or its biofilm, serving as food source rather than refugium per se. Similarly, Tegula funebralis chose CWD as food source rather than as shelter as indicated by comparison of autoclaved and unmanipulated woody debris. Further, both unfed and fed snails from a site where CWD was present significantly preferred CWD over macroalgae. Among snails from a site without woody debris, fed individuals showed no preference, while unfed snails significantly preferred macroalgae. From this, experience appears to be a factor that mediates the role of CWD. Overall, however, CWD appears to provide supplementary food to snails in the inter- and supratidal zone.
Does variation in morphology correspond with variation in habitat use in freshwater gastropods?
Hydrobiologia, 2014
8 Abstract We tested if variations (i.e., breadth) in 9 morphology and habitat use vary predictably among six 10 aquatic gastropod species that were collected across 11 Indiana and Illinois, USA. We predicted that interspecific 12 morphological variation would positively covary with 13 variation in habitat use among species. We used 14 geometric morphometrics (Procrustes technique and 15 relative warp analysis) to quantify morphology and 16 multivariate analyses (PCA) to quantify habitat. 17 Increased morphological breadth did not vary predict-18 ably with increased habitat breadth. However, we found 19 that life history traits correspond with patterns in 20 morphological and habitat breadth for these six aquatic 21 gastropods. Pulmonate gastropods (use lungs for respi-22 ration) that lack an operculum cover exhibited decreased 23 morphological breadth compared to coenogastropods 24 (use gills for respiration). This pattern may ultimately be 25 a function of behavioral adaptations in freshwater 26 gastropods. Gastropods that are capable of breathing air 27 or using other behavioral modifications such as burrow-28 ing to escape predators may not require high morpho-29 logical breadth. Conversely, selection may favor higher 30 morphological breadth in gastropods with gills that also 31 do not move out of the water column to escape predators. 32 Keywords Morphological niche Á Habitat 33 niche Á Niche breadth Á Geometric 34 morphometrics Á Gastropod ecology 35 36 A1 Handling editor: Sonja Stendera A2 Electronic supplementary material The online version of A3 this article (
Forest Ecology and Management, 2014
Climate-induced disturbances such as hurricanes affect the structure and functioning of many ecosystems, especially those in the Caribbean Basin, where effects are well documented with regard to biodiversity and biogeochemical dynamics. Because climate change will likely alter the frequency or intensity of such storms, it is increasingly important to understand the mechanistic bases for ecosystem responses. However, this is particularly difficult to do in the absence of manipulative experiments that decouple confounded factors such as canopy opening and debris deposition. To address this issue, we exploited a replicated factorial design to experimentally distinguish the effects of canopy opening and debris deposition on population-and community-level characteristics of gastropods in the Luquillo Experimental Forest of Puerto Rico. Despite considerable spatial variation, abundances of all gastropods (combined) as well as abundances of each of 3 species (i.e., Alcadia striata, Platysuccinea portoricensis, and Polydontes acutangula) responded significantly to canopy opening while abundances of each of 2 species (i.e., Pl. portoricensis, and Po. acutangula) responded significantly to debris deposition within two years of experimental manipulation. In contrast, two species (i.e., Gaeotis nigrolineata and Nenia tridens) did not respond to any experimental manipulations in the short term. Moreover, species composition did not differ between pre-and post-manipulation periods, in part because of considerable variation among replicated blocks. In contrast, canopy removal consistently affected species richness, Shannon diversity, and rarity, while debris deposition consistently affected species richness and Shannon diversity. Neither treatment affected species dominance or evenness. Longer-term responses of the gastropod fauna were more complex. Although considerable interspecific heterogeneity characterized responses of the gastropod fauna, temporal variation in mean abundance for each of the three manipulative treatments was similar to that of the non-manipulated treatment when abundances were combined for all species. In contrast, temporal variation in each of the manipulative treatments was unrelated to temporal variation in the non-manipulated treatment for species richness, evenness, dominance, and rarity. Moreover, temporal variation in abundance generally differed between at least two of the manipulative treatments for most species and temporal variation in components of taxonomic biodiversity generally differed between manipulative treatments as well. Temporal variation in species composition was considerable and comparable for each of the four treatment combinations. Species composition within each treatment combination varied over time in ways unrelated to temporal variation in the other treatment combinations, including the reference treatment (i.e., no canopy trimming and no debris addition). Manipulated treatments were surrounded by large areas of intact forest, and tabonuco forest generally exhibits appreciable spatial and temporal variation. Natural spatiotemporal variation in the study system likely overwhelmed many of the effects of experimental manipulations on gastropod populations or communities via edge effects and recruitment of individuals from nearby less disturbed portions of the landscape.
2018
Community dynamics of gastropods were studied from four selected intertidal locations along an18km long coastal stretch on the east coast of south Andaman Islands. A total of 71 taxa belonging to 17 families and 3 orders were identified. While Nassariidae (31.15%) made maximal contribution to faunal abundance, Muricidae (11 species) and Conidae (9 species) were mainly responsible for changes in diversity patterns. In general, abundance and diversity exhibited a reversing trend. Most diverse area (H’=1.816±0.49 and d= 2.68±0.97) was found in the middle of the southeast coastal stretch. Multivariate analysis revealed the presence of location-specific gastropod assemblages spearheaded by Nassarius spp. and Nerita spp. The results yielded a potential positive correlation between locations and gastropod diversity along the entire coastal stretch.
Marine Ecology Progress Series, 2012
Many assemblages contain numerous rare species, which can show large increases in abundances. Common species can become rare. Recent calls for experimental tests of the causes and consequences of rarity prompted us to investigate competition between co-existing rare and common species of intertidal gastropods. In various combinations, we increased densities of rare gastropod species to match those of common species to evaluate effects of intra-and interspecific competition on growth and survival of naturally rare or naturally common species at small and large densities. Rarity per se did not cause responses of rare species to differ from those of common species. Rare species did not respond to the abundances of other rare species, nor show consistently different responses from those of common species. Instead, individual species responded differently to different densities, regardless of whether they are naturally rare or abundant. This type of experimental evidence is important to be able to predict the effects of increased environmental variability on rare as opposed to abundant species and therefore, ultimately, on the structure of diverse assemblages.
Frontiers in Marine Science, 2020
The tegulid gastropod, Rochia nilotica is harvested in small-scale fisheries throughout Southeast Asia and the Pacific Islands, many of which were created from inter-country translocations. This species is found on structurally complex shallow reefs, but its specific habitat requirements have not yet been quantified in order to maximize the success of future translocations and help future-proof the fishery in changing ocean conditions. At 28 sites around Samoa, where the species was introduced in the early 2000s, we measured a suite of habitat variables along transects in which R. nilotica were counted and the shell sizes measured in a parallel study. Boosted regression tree analyses revealed that R. nilotica were most abundant at reef locations that were shallow, with fairly consistent depth, had high coverage of branching coral, low cover of erect macroalgae, low wave exposure and high surface complexity. Smaller individuals were associated with wide reef flats and high cover of branching coral, whereas larger animals occurred in deeper water with high surface complexity. Multivariate analyses showed this species to be a habitat generalist, sharing much of its niche with an endemic herbivorous gastropod, Tectus pyramis. Future stocking programs should focus on sites with habitats optimal for both adults and juveniles. R. nilotica populations are likely to be especially affected by broadscale stressors that result in declines in live coral cover and substratum complexity and increasing coverage of macroalgae on coral reefs.