Continuing trophic studies on constructed “restored” oyster reefs

AMASS choreographed by Eloy Barragán. Color is removed from the low sidelight, creating a natural warmth highlighting the individual dancers as if floating in space.https://ir.uiowa.edu/lighting_design/1189/thumbnail.jp

Habitat Disturbance Combined With Life History Traits Facilitate Establishment Of Rapana Venosa In The Chesapeake Bay

The veined rapa whelk (Rapana renosa) invasion of the Chesapeake Bay in the United States was first observed in 1998. Chesapeake Bay rapa whelk population demographics, age-at-length relationships, and invasion progression (temporal, spatial) from 1998 to 2009 are described. Between June 1998 and November 2009, 27,624 rapa whelks, ranging from 11- to 195 mm shell length (SL), were collected from the lower Bay. Using a Von Bertalanffy age-at-length model (R-2=0.99), the 195-mm SL whelk collected in 2007 was 26 y old, making 1981 the estimated year of first introduction. Age-frequency distributions for Ocean View, Hampton Bar, and the lower James River showed increased whelk numbers per age class and consistent representation of Age 2-3 through Age 7-8 whelks throughout the time series indicating recruitment and establishment. Whelk range expansion into James River oyster habitats began in 2004 and continued through 2009. Whelks occupy shallow areas during warmer months, move into deeper habitats during cooler months, and annually reinvade shallow areas as temperatures warm seasonally. Channels act as salinity refugia and conduits between foraging habitats. Salinity tolerances allow rapa whelk use of epifau.nal habitats bounded by the 10-12 isohalines formerly used by native oyster drills [Urosalpinx cinerea (Say, 1822); Eupleura caudata (Say. 1822)] as juveniles and infaunal habitats with salinities of 15-25 that do not overlap with native whelks (Busycotypus canailculatus, liusycon carica) as adults. Establishment was facilitated by local disturbance of native species distributions by Tropical Storm Agnes (1972)

Oyster reefs as fish habitat: Opportunistic use of restored reefs by transient fishes

Under the Magnuson-Stevenson Fisheries Management Act of 1996, current fisheries management practice is focused on the conce_pt of Essential Fish Habitat (EFH). Application of the EFH concept to estuarine habitats relates directly to ongoing oyster reef restorat10n efforts. Oyster reef restoration typically creates complex habitat in regions where such habitat is limited or absent. While healthy oyster reefs provide structurally and ecologically complex habitat for many other species from all trophic levels including recreationally and commercially valuable transient finfishes, additional data is required to evaluate oyster reef habitats in the context of essential fish habitat. Patterns of transient fish species richness,. abundance, and size-specific habitat use were examined along an estuarine habitat gradient from complex reef habitat through simple sand bottom in the Piankatank River, Virginia. There was no clear delineation of habitat use by transient fishes along this cline of estuarine habitat types (oyster reef to sand bar). Atlantic croaker (Micropogonias undulatus), Atlantic menhaden (Brevoortia tyramws), bluefish (Pomatomus saltatrix), silver perch (Bairdiel/a chi)•soura), spot (Leiostomus xanthurus), spotted seatrout (Cynoscion regalis), striped bass (Marone saxatilis), and weakfish (Cynoscion nebulosus) were found in all habitat types examined. In general, the smallest fish were found on the sand bar, the site with the least habitat heterogeneity. As habitat complexity increased along the gradient from oyster shell bar through oyster reef, transient fish size and abundance increased. Opportunistic habitat use by this suite of generalists relates variations in habitat quality as related to habitat-specific productivity and suggests that oyster reefs may be important but not essential habitat for these fishes

Shell Length-At-Age Relationships In James River, Virginia, Oysters (Crassostrea Virginica) Collected Four Centuries Apart

Eastern oysters were ecologically and structurally dominant features of the Chesapeake Bay prior to European colonization. Four centuries of harves pressure, habitat degradation, and more recently, disease activity have affected extant oyster population demographics. We compared population demographics and age-at-shell length relationships for modern mesohaline James River oyster populations with James River oysters collected in the years 1611 to 1612 by Jamestown settlers. Historic oyster collections made by hand included a more complete demographics than modern samples collected with patent longs. Historic oysters had significantly faster growth rates than modern oyster populations. Modern oysters larger than 30-40 mm SL or age 1 grow more slowly than historic oysters of comparable ages. Unlike historic oyster populations, modern james River oyster populations are affected by Dermo and MSX. The downward trend observed in the modern age at length relationships (Fig. 4B see later) between 1 to 1.6 y is probably related to the seasonal onset of disease with increasing temperatures. Observed changes in oyster demographics and growth rates across four centuries reflect changes in the environment as well as changes in oyster biology because of chronic pressure from two oyster diseases

The Status of Virginia\u27s Public Oyster Resource 2010

This report summarizes data collected during 2010 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

The Status of Virginia\u27s Public Oyster Resource 2010

This report summarizes data collected during 2010 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

The Status of Virginia\u27s Public Oyster Resource 2010

This report summarizes data collected during 2010 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

Rundown on the Rapa : activity booklet for educators

This booklet provides hands-on classroom activities that can be used to reinforce concepts discussed in Rundown on the Rapa. All booklet activities are tied to middle and high school national science education standards as well as to specific Virginia Math, Life Science, and Biology SOL. The activities encourage problem solving and critical thinking skills. This booklet is intended as a companion to the VORTEX Instructional Booklet RUNDOWN ON THE RAPA. These activities have been designed to help science educators reinforce concepts presented in the RUNDOWN ON THE RAPA Instructional Booklet. See: https://doi.org/10.21220/V5MN1

The Effects Of Female Size On Fecundity In A Large Marine Gastropod Rapana Venosa (Muricidae)

The life history strategy of the veined rapa whelk Rapana venosa, a temperate marine gastropod, includes generation times of 1 y, individual longevity of \u3e 10 y, annual production of egg cases, and an adult size range of 40 to \u3e 160 mm shell length (SL). This life history combined with the animal\u27s generalist ecological preferences and broad physiological tolerances makes rapa whelks well suited for ecological success along a gradient of habitat and community types. Ballast water transport of veliger larvae across traditional zoogeographic boundaries has resulted in the establishment of invasive rapa whelk populations in Chesapeake Bay, USA, as well as European habitats. Although the need for a quantitative understanding of rapa whelk reproductive biology in terms of annual embryo production or fecundity is acknowledged as a necessary step in assessing the biological and ecological consequences of such an invasion, rapa whelk fecundity in relation to size for the entire adult size range (40-\u3e 160 mm SL) has not previously been quantified. The relationships between rapa whelk female size and egg case height, number of embryos egg case(-1), number of egg cases produced female whelk(-1) yr(-1) and fecundity, and the number of embryos female-(1) yr(-1), are described for a size range of individuals from Chesapeake Bay. In 2001 and 2003, egg laying began in mid to late May at water temperatures of approximately 18 degrees C and salinities 14-20 ppt and continued for 11-12 wk. The smallest rapa whelk observed (45 mm SL, 5.8 g wet tissue weight) laid egg cases with heights of approximately 7 mm. The largest whelk (163 mm SL, 220 g) laid egg cases with heights 30-33 mm. The number of embryos observed in egg cases produced by Chesapeake Bay rapa whelks ranged from 123 embryos in a 7.4 mm high egg case to 3,673 embryos in a 33.5 mm high egg case. Rapa whelk fecundity (number of embryos female(-1)yr(-1)) increased with female size. Egg case production was observed in rapa whelks that had hatched from egg cases and recruited within the previous year (\u3c 1 y old). Small (\u3c 80 mm SL, \u3c 28 g wet tissue weight) rapa whelks have relatively lower annual fecundities (1 x 10(5) embryos fernale(-1) yr(-1)) than large (\u3e 80 mm SL, \u3e 28 g wet tissue weight) rapa whelks that may produce between 1 x 10(6) and 4 x 10(6) embryos female(-1) yr(-1). Estimates of rapa whelk fecundity, even for small rapa whelks, are at least an order of magnitude greater than similar estimates for native United States Atlantic coast gastropods