No abstract

Spatial hierarchical approaches to classify freshwater systems can add to our understanding of biogeographical patterns and can be used for biodiversity conservation planning. The Strawberry River is located primarily in the Ozark Highlands Central Plateau of north central Arkansas, USA, with a small downstream portion in the Mississippi Alluvial Plain and has been designated an Extraordinary Resource Water, an Ecologically Sensitive Water Body, and a Natural Scenic Waterway. The goals of this study were to document Strawberry River, Arkansas freshwater mussels to aid in conservation planning. Our first objective was to inventory freshwater mussel species in the Strawberry River. Our second objective was to use this stream-wide dataset to classify the freshwater mussel assemblages. We used unpublished survey data of 59 sites distributed from the headwaters to the mouth to inventory species occurrence and abundance, classified mussel assemblages using non-metric multi-dimensional scaling (NMS), and conducted indicator species analysis on resulting assemblages. We observed 39 taxa across the 59 survey sites including two S1, five S2, 16 S3, 11 S4, four S5, and one state non-ranked conservation rank species. Furthermore, our assemblage NMS revealed two distinct freshwater mussel assemblages roughly organized by an upstream (Sites 1–31) to downstream (Sites 32–59) gradient. There were five upstream indicator species and 13 downstream indicator species. This study provides a case study on using existing datasets with NMS and indicator species analyses to classify mussel assemblages and adds to our understanding of freshwater mussel fauna classification at smaller spatial scales. Both NMS and indicator species outcomes can aid in conservation planning for freshwater mussels.

Freshwater mussel assemblages show predictable variation according to large-scale biogeographic factors and stream-size gradients, but smaller-scale assemblage patterns are less well known. The goal of this study was to classify and delineate mussel assemblages of the Black River, Missouri and Arkansas, USA, along an upstream-downstream gradient and with regard to physiography and biogeographical regions. We analyzed mussel assemblages using nonmetric multidimensional scaling and indicator-species analysis. Our results yielded three assemblage groupings distributed along the upstream-downstream gradient and thereby considered aquatic ecological systems (100-1,000 km 2 ) in a hierarchical spatial classification scheme. These groupings also support previously proposed biogeographical differences for mussels and fishes between the Ozark Highlands and Mississippi Alluvial Plain physiographic regions. Each group was characterized by 2-13 indicator species. Our demonstration of small-scale patterns of mussel assemblage change will be useful for conservation planning and for a better understanding of mussel assemblage dynamics.

Land use changes remain one of the leading global change drivers leading to biodiversity loss in terrestrial and aquatic systems. Restoration aims to counteract the development of “natural” (i.e., forested, grassland, or wetland) spaces that alter and fragment the landscape and reduce local biodiversity through direct impacts to the water column and indirect impacts which inhibit adult dispersal of aquatic insects. This case study seeks to determine if a large-scale restoration of a former cranberry bog in Plymouth, MA has resulted in near-term measurable changes to the composition, structure, and function of local-scale in-stream habitat diversity. A three-year observational field study beginning one year prior to reconstruction was conducted at the restored cranberry bog and at two control treatment sites: an active cranberry bog reference and a least impacted reference (i.e., has never been used for modern agriculture). Seasonal inventories of in-stream habitat features including depth, substrate, macrohabitat, and in-stream cover were taken from 2015 to 2017. We found that 2 years post-restoration, there was no significant evidence of compositional or functional change, while there was a significant increase in structural diversity. There is reason to suspect the system is still in flux and longer-term monitoring may detect future habitat heterogeneity alterations.