This study aimed to identify the importance of ecological factors to distribution patterns of the invasive Clam (
Invasive species introduction is one of the major ongoing ecological global crises. Identifying factors responsible for the success of invasive species is key for the implementation of effective management actions. The invasive filter-feeding bivalve,
- Award ID(s):
- 1831512
- NSF-PAR ID:
- 10366909
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Biological Invasions
- Volume:
- 24
- Issue:
- 6
- ISSN:
- 1387-3547
- Page Range / eLocation ID:
- p. 1677-1688
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Corbicula fluminea ) relative to native mussels (family: Unionidae) across seven rivers within the Mobile and Tennessee basins, Southeast United States. We quantitatively surveyed dense, diverse native mussel aggregations across 20 river reaches and estimated mussel density, biomass, and species richness along with density of invasiveC .fluminea (hereafterCorbicula ). We measured substrate particle size, velocity, and depth in quadrats where animals were collected. Additionally, we characterized reach scale environmental parameters including seston quantity and quality (% Carbon, % Nitrogen, % Phosphorous), water chemistry (ammonium [], soluble reactive phosphorous [SRP]), and watershed area and land cover. Using model selection, logistic regression, and multivariate analysis, we characterized habitat features and their association to invasiveCorbicula within mussel beds. We found thatCorbicula were more likely to occur and more abundant in quadrats with greater mussel biomass, larger substrate size, faster water velocity, and shallower water depth. At the reach scale,Corbicula densities increased where particle sizes were larger. Mussel richness, density, and biomass increased with watershed area. Water column increased at reaches with more urban land cover. No land cover variables influencedCorbicula populations or mussel communities. The strong overlapping distribution ofCorbicula and mussels support the hypothesis thatCorbicula are not necessarily limited by habitat factors and may be passengers of change in rivers where mussels have declined due to habitat degradation. WhetherCorbicula is facilitated by mussels or negatively interacts with mussels in these systems remains to be seen. Focused experiments that manipulate patch scale variables would improve our understanding of the role of species interactions (e.g., competition, predation, facilitation) or physical habitat factors in influencing spatial overlap betweenCorbicula and native mussels. -
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Abstract The consequences of land‐use change for savanna biodiversity remain undocumented in most regions of tropical Asia. One such region is western Maharashtra, India, where old‐growth savannas occupy a broad rainfall gradient and are increasingly rare due to agricultural conversion and afforestation.
To understand the consequences of land‐use change, we sampled herbaceous plant communities of old‐growth savannas and three alternative land‐use types: tree plantations, tillage agriculture and agricultural fallows (
n = 15 sites per type). Study sites spanned 457 to 1954 mm of mean annual precipitation—corresponding to the typical rainfall range of mesic savannas globally.Across the rainfall gradient, we found consistent declines in old‐growth savanna plant communities due to land‐use change. Local‐scale native species richness dropped from a mean of 12 species/m2in old‐growth savannas to 8, 6 and 3 species/m2in tree plantations, fallows and tillage agriculture, respectively. Cover of native plants declined from a mean of 49% in old‐growth savannas to 27% in both tree plantations and fallows, and 4% in tillage agriculture. Reduced native cover coincided with increased cover of invasive species in tree plantations (18%), fallows (18%) and tillage agriculture (3%).
In analyses of community composition, tillage agriculture was most dissimilar to old‐growth savannas, while tree plantations and fallows showed intermediate dissimilarity. These compositional changes were driven partly by the loss of characteristic savanna species: 65 species recorded in old‐growth savannas were absent in other land uses. Indicator analysis revealed 21 old‐growth species, comprised mostly of native savanna specialists. Indicators of tree plantations (nine species) and fallows (13 species) were both invasive and native species, while the two indicators of tillage agriculture were invasive. As reflective of declines in savanna communities, mean native perennial graminoid cover of 27% in old‐growth savannas dropped to 9%, 7%, and 0.1% in tree plantations, fallows and tillage agriculture, respectively.
Synthesis . Agricultural conversion and afforestation of old‐growth savannas in India destroys and degrades herbaceous plant communities that do not spontaneously recover on fallowed land. Efforts to conserve India's native biodiversity should encompass the country's widespread savanna biome and seek to limit conversion of irreplaceable old‐growth savannas. -
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Abstract Coastal communities increasingly invest in natural and nature‐based features (e.g., living shorelines) as a strategy to protect shorelines and enhance coastal resilience. Tidal marshes are a common component of these strategies because of their capacity to reduce wave energy and storm surge impacts. Performance metrics of restoration success for living shorelines tend to focus on how the physical structure of the created marsh enhances shoreline protection via proper elevation and marsh plant presence. These metrics do not fully evaluate the level of marsh ecosystem development. In particular, the presence of key marsh bivalve species can indicate the capability of the marsh to provide non‐protective services of value, such as water quality improvement and habitat provision. We observed an unexpected low to no abundance of the filter‐feeding ribbed mussel,
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