Age,Growth, and Reproductive Biology of Cownose Rays in Chesapeake Bay

Abstract

The Cownose Ray Rhinoptera bonasus is an opportunistic predator of benthic invertebrates and has had a long history of negative interactions with commercial shellfish industries. Most recently, Cownose Rays have been implicated in negatively affecting the recovery of bay scallop Argopecten irradians stocks in North Carolina and oyster restoration and commercial aquaculture efforts in Chesapeake Bay. A mitigation attempt to decrease predation on shellfish has resulted in an unregulated fishery for Cownose Rays. Cownose Ray life history suggests that they are highly susceptible to overexploitation. We determined age, growth, and size at maturity for Cownose Rays collected in Chesapeake Bay. In total, 694 rays were used for the study: 246 males ranging in size from 30.0 to 98.0 cm disc width (DW) and 448 females ranging from 30.0 to 110.5 cm DW. The oldest individual observed was a female (107 cm DW) estimated at age 21. Our data suggested that Cownose Rays grow considerably faster during the first few years than has been previously reported, thus producing higher estimates of the growth coefficient k. The best-fit growth models (three-parameter von Bertalanffy models) estimated k-values of 0.2741 for males and 0.1931 for females. The large sample size and inclusion of many older animals (n = 119 rays over age 10) resulted in theoretical maximum size estimates that matched the observed sizes well. The median size at 50% maturity was 85–86 cm DW for males and females (corresponding to ages of ～6–7 for males and ～7–8 for females). Fecundity in Cownose Rays was typically one embryo per mature female, with a gestation period of 11–12 months. Our study confirms that the Cownose Ray is a K-selected species with late maturity, long gestation, and low reproductive potential, indicating that it could be highly susceptible to overexploitation.

Received February 28, 2013; accepted June 3, 2013     

Clinical Decision Support to Promote Safe Prescribing to Women of Reproductive Age: A Cluster-Randomized Trial

BACKGROUND

Potentially teratogenic medications are frequently prescribed without provision of contraceptive counseling.

OBJECTIVE

To evaluate whether computerized clinical decision support (CDS) can increase primary care providers?? (PCPs??) provision of family planning services when prescribing potentially teratogenic medications.

DESIGN

Cluster-randomized trial conducted in one academic and one community-based practice between October of 2008 and April of 2010.

PARTICIPANTS/INTERVENTIONS

Forty-one PCPs were randomized to receive one of two types of CDS which alerted them to risks of medication-induced birth defects when ordering potentially teratogenic medications for women who may become pregnant. The ??simple?? CDS provided a cautionary alert; the ??multifaceted?? CDS provided tailored information and links to a structured order set designed to facilitate safe prescribing. Both CDS systems alerted PCPs about medication risk only once per encounter.

MAIN MEASURES

We assessed change in documented provision of family planning services using data from 35,110 encounters and mixed-effects models. PCPs completed surveys before and after the CDS systems were implemented, allowing assessment of change in PCP-reported counseling about the risks of medication-induced birth defects and contraception.

KEY RESULTS

Both CDS systems were associated with slight increases in provision of family planning services when potential teratogens were prescribed, without a significant difference in improvement by CDS complexity (p?=?0.87). Because CDS was not repeated, 13% of the times that PCPs received CDS they substituted another potential teratogen. PCPs reported significant improvements in several counseling and prescribing practices. The multifaceted group reported a greater increase in the number of times per month they discussed the risks of medication use during pregnancy (multifaceted: +4.9?±?7.0 vs. simple: +0.8?±?3.2, p?=?0.03). The simple CDS system was associated with greater clinician satisfaction.

CONCLUSIONS

CDS systems hold promise for increasing provision of family planning services when fertile women are prescribed potentially teratogenic medications, but further refinement of these systems is needed.     

Endocrine adaptation to osmotic requirements of the environment: Endocrine factors in osmoregulation by lungfishes and amphibians

Arginine vasotocin (AVT) occurs in the neurohypophyses of lungfishes and amphibians. Injected AVT is diuretic in lungfishes and antidiuretic in anuran amphibians. A new radioimmunoassay for AVT has been used in an effort to define whether AVT has endocrine functions related to osmoregulation and to attempt to demonstrate the factors that influence its release. Preliminary experiments on bullfrogs suggest that decreased blood volume or pressure is a more important stimulus for the release of AVT than plasma hyperosmolality. Factors other than AVT appear important in controlling water excretion by bullfrogs.