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The Southeastern USA is currently experiencing a period of rapid growth of human populations that is likely having profound effects on the region’s unique aquatic biota. Using both survey data and experimental protocols, we assessed the influences of water and habitat quality on freshwater mussel populations in a small Piedmont stream. Chewacla Creek is a high-quality stream located near the rapidly growing towns of Auburn and Opelika in east-central Alabama. From 1999 to 2007 we monitored freshwater mussel populations and measured substrate and water chemistry variables in Chewacla Creek. Surveys revealed that mussel abundance decreased substantially concomitant with degraded habitat and water quality downstream of three highly urbanized tributaries. We conducted sentinel trials using adult mussels ( Villosa lienosa) in Chewacla Creek and a tributary (Parkerson Mill Creek) that receives wastewater discharge. Sentinel mussels were placed in cages at three locations downstream of the effluent discharge point and at one upstream site (control). Sentinel mussels exposed to wastewater discharge exhibited lower survival rates compared to control animals. Together, survey and experimental data suggest that degraded tributary sub-catchments may fragment mussel populations in high-quality streams. Moreover, our data indicate that protection of sensitive aquatic taxa necessitates effective management of water quality across large spatial scales. [ABSTRACT FROM AUTHOR]

Abstract: Juvenile red king crab (Paralithodes camtschaticus) mass rearing was conducted in Seward, Alaska, USA in a king crab stock enhancement feasibility study. Hatchery-raised juveniles were cultured from larvae of 12 ovigerous females collected from Bristol Bay, Alaska, USA. Juvenile instars were cultured in nursery grow-out containers in two phases: (1) C1–C3 juveniles and (2) C3–C6 juveniles. Experiments lasted for 42 and 44 days, respectively, and tested the suitability of various diets, stocking densities and substrates in terms of survival rate and growth. The first experiment (C1–C3) compared fully-factorial treatments of three diets (Cyclop-eeze®, enriched Artemia nauplii, or Zeigler™ shrimp feed), three stocking densities (500 m−2, 1000 m−2, or 2000 m−2), and two substrates (none or a combination of artificial seaweed, gillnet, and mechanical biofilter medium). The second experiment (C3–C6) used a mixed diet and compared fully-factorial treatments of two stocking densities of 800 m−2 and 1600 m−2 and two substrates (as above). No one food produced the highest survival and growth to C3. Cyclop-eeze® yielded highest survival (62.7%) with low growth (wet weight 8.63 mg and CW 2.04 mm). Crabs on shrimp nursery feed had the highest wet weight (10.0 mg) and CW (2.14 mm) but with low survival (44.5%). The highest stocking density resulted in a decrease in survival in both experiments. Lower stocking densities of 500 m−2 and 800 m−2 had relatively high survival of 58.7% and 48.7%, respectively, while the 1600 m−2 and 2000 m−2 densities had survival of 30.5% and 44.7%, respectively. Growth appeared to be inhibited at the highest density (2000 m−2) in the C1 to C3 stages, as crabs at this density were smaller and weighed less than at the 500 m−2 or 1000 m−2 density. Complex artificial substrate increased survival and reduced growth in both experiments, likely due to reduced cannibalism and increased time spent foraging. Among substrate treatments, highest abundances of crabs were observed on artificial seaweed, which may more closely resemble preferred natural substrate. These results suggest that culturing red king crab juveniles at low to intermediate stocking densities with a mixed diet in the presence of artificial substrate provides good survival. Intermediate densities may provide for greater production without great loss in survival. [Copyright &y& Elsevier]

This study examined the phylogeography and population demographics of Cambarus tenebrosus, which has an unusually large distribution for a freshwater crayfish species, encompassing the Interior Lowlands and Cumberland Plateau of the eastern United States. This facultative cave-dweller provides a unique perspective on the biologic connections between surface and subsurface freshwater ecosystems, which are considered to be highly imperiled due to pollution and habitat degradation. The 16S mitochondrial gene was sequenced for 233 individuals from 84 cave and 20 surface locations throughout the range, with most sampling concentrated around the Cumberland Plateau of the southern Appalachians, to assess conservation status of this species and examine the extent of gene flow between the two habitat types. Cave and surface populations formed a single monophyletic group relative to Cambarus striatus, and clades showed strong geographical associations, but lacked habitat structuring. Occupation of subterranean environments does not appear to be a recent event in the evolutionary history of the species. The large amount of genetic diversity within the species, coupled with its ability to inhabit surface and subsurface environments, suggests that this species may pose a threat as a possible invasive species in other karst-dominated landscapes. [ABSTRACT FROM AUTHOR]

During the 1890s, people on the Mississippi River exploited mussel populations to support a thriving button industry. Within a brief time, they noticed significant declines in mussel populations, and called on the U.S. Bureau of Fisheries to save the resource. This paper discusses mussel propagation studies, techniques, and activities carried on in association with the Fairport Biological Laboratory (Iowa) from about 1908 to 1932. While scientists developed sophisticated techniques and had success in mussel propagation, changing habitat conditions in the river (caused mainly by pollution and dam construction) meant limited success in rescuing mussel stocks, while the introduction of plastic and the growth of foreign sources of mussel shells influenced the decline of the button industry on the Mississippi River. [ABSTRACT FROM AUTHOR]

Mississippi River alluviation has provided Louisiana with a deltaic coast which contrasts sharply with the remainder of the Gulf littoral. Salient differences lie in coast configuration, hydrographic patterns, water chemistry, sediments, and vegetation. Although the species of marine life are largely the same here as elsewhere in the Gulf area, their ecology is closely governed by and geared to the highly fluctuating deltaic environment. The mud bottoms, decaying marsh grass, and nutrients provided by the Mississippi River are especially favorable for an abundant shellfish population. The very productive fisheries of Louisiana are largely concerned with shellfish production and such plankton feeders as menhaden. The fisheries are concentrated in those coastal areas most actively influenced by the Mississippi drainage.