Environmental and Endogenous Factors Influencing Emigration in Juvenile Anadromous Alewives

We analyzed juvenile anadromous alewife migration at Bride Lake, a coastal lake in Connecticut, during summer 2006 and found that migration on 24-hour and seasonal timescales was influenced by conditions of the environment and characteristics of the individual. To identify environmental cues of juvenile migration, we continuously video recorded fish at the lake outflow and employed information-theoretic model selection to identify the best predictors of daily migration rate. More than 80% of the approximately 320,000 juveniles that migrated from mid-June to mid-August departed in three pulses lasting one or two days. Pulses of migration were associated with precipitation events, transient decreases in water temperature and transient increases in stream discharge. Diel timing of migration shifted over the summer. Early in the season most migration occurred around dawn; late in the season migration occurred at night. To identify individual characteristics associated with migratory behavior, we compared migrating juveniles that we collected as they were exiting Bride Lake to non-migrating juveniles that we collected from the center of the lake. Migrants were a non-random subset of the population; they were on average 1 – 12 mm larger, 2 – 14 d older, had grown more rapidly (11% greater length-at-age), and were in better condition (14% greater mass-at-length) than non-migrant fish. We infer that the amount of accumulated energy has a positive effect on the net benefit of migration at any time in the migratory season.

Anadromous Rainbow Smelt and Tomcod in Connecticut: Assessment of populations, conservation status, and need for restoration plan

(beginning of rainbow smelt executive summary) Evidence indicates that anadromous rainbow smelt (Osmerus mordax) populations in Connecticut and elsewhere in the northeast United States have severely declined. Several sampling programs have documented declines in Connecticut’s smelt populations over the last three decades (Marcy 1976a, Marcy 1976b, Millstone Environmental Laboratory 2005). Similar declines have also been documented in the Hudson River (ASA Analysis & Communication 2005) and in Massachusetts (personal communication, Brad Chase, MA Division of Marine Fisheries 2004). Recreational and commercial fisheries in the region for this species have virtually ceased (Blake and Smith 1984). The Connecticut Fish Advisory Committee of the Endangered Species Program has recommended that rainbow smelt be listed as threatened in Connecticut, and the National Marine Fisheries Service (2004) has recently listed rainbow smelt as a Federal Species of Concern. The purpose of this project is to develop an environmental history of rainbow smelt in Connecticut and surrounding regions, and document the current status of populations in Connecticut waters. An environmental history that assesses trends in abundance, environmental threats and historical efforts to ameliorate the threats will contribute to regional efforts to conserve these fish. Comprehensive review of the regional literature and trends associated with rainbow smelt has not been undertaken since Kendall (1926). Assessment of current abundance, distribution, areas of critical habitat, and whether the species is presently reproducing in state waters is critical for clarifying conservation status, designing a monitoring program and developing a recovery or enhancement plan, if this appears to be necessary. (beginning of tomcod executive summary) Atlantic tomcod (Microgadus tomcod) are believed to have declined significantly in Connecticut and other estuaries of the Northeast and Middle Atlantic states. Several monitoring programs indicate that the species is scarce and/or declining in the region’s estuaries (Gottschall and Pacileo 2004, Molnar 2004, Millstone Environmental Laboratory 2005, ASA Analysis and Communication 2005). Once-active recreational (NMFS MRFSS 2005, http://www.st.nmfs.gov) and commercial fisheries for this species in Connecticut are now dormant. For the past 10 years, the Connecticut Fish Advisory Committee of the Endangered Species Program has recommended that studies be undertaken to quantify the status of tomcod populations and to determine if conservation actions should be initiated. The purpose of this project is to develop an environmental history of Atlantic tomcod in Connecticut and surrounding regions, and document the current status of populations in Connecticut waters. An environmental history that assesses trends in abundance, environmental threats and historical efforts to ameliorate the threats will contribute to regional efforts to conserve these fish. Assessment of current abundance, distribution, areas of critical habitat, and whether the species is presently reproducing in state waters is critical for determining conservation status, designing a monitoring program and developing a recovery or enhancement plan, if this appears to be necessary.

Ontogenetic Effects of Hatching Plasticity in the Spotted Salamander (Ambystoma maculatum) due to Egg and Larval Predators

The ability to respond plastically to the environment has allowed amphibians to evolve a response to spatial and temporal variation in predation threat (Benard 2004). Embroys exposed to egg predation are expected to hatch out earlier than their conspecifics. Larval predation can induce a suite of phenotypic changes including growing a larger tail area. When presented with cues from both egg and larval predators, embryos are expected to respond to the egg predator by hatching out earlier because the egg predator presents an immediate threat. However, hatching early may be costly in the larval environment in terms of development, morphology, and/or behavior. We created a laboratory experiment in which we exposed clutches of spotted salamander (Ambystoma maculatum) eggs to both egg (caddisfly larvae) and larval (A. opacum) predators to test this hypothesis. We recorded hatching time and stage and took developmental and morphological data of the animals a week after hatching. Larvae were entered into lethal predation trials with a larval predatory sunfish (Lepomis sp.) in order to study behavior. We found that animals exposed to the egg predator cues hatched out earlier and at earlier developmental stages than conspecifics regardless of whether there was a larval predator present. Animals exposed to larval predator cues grew relatively larger tails and survived longer in the lethal predation trials. However the group exposed to both predators showed a cost of early hatching in terms of lower tail area and shorter survival time in predation trials. The morphological and developmental effects measured of hatching plasticity were transient as there were no developmental or morphological differences between the treatment groups at metamorphosis. Hatching plasticity may be transient but it is important to the development and survival of many amphibians.

When hybrids go wrong. How hybridization can create invasive species.

Gene flow is the movement of genes from one plant population to another. Gene flow is a natural process and a part of plant evolution. There are two ways for gene flow to occur in plants. The first is through sexual reproduction – pollen lands on a flower and a viable seed develops. The second method is through dispersal of seeds and/or vegetative plant parts (e.g. stolons, rhizomes). Gene flow can produce hybrid offspring with an increased or decreased ability to survive in the landscape. If hybrid offspring have some advantage in the environment, they could become invasive. This poster shows two examples of gene flow in plants and the potential for environmental damage.

The Role of Raf Kinase Inhibitor Protein in Cell Motility

Raf Kinase Inhibitor Protein (RKIP) has been identified as a phosphatidylethanolamine-binding protein capable of inhibiting Raf-1 kinase, an enzyme significant in cell proliferation and cancer development. When properly functioning, RKIP can mediate the expression of Raf-1 kinase and help prevent uncontrolled cell division. RKIP also has suggested, but unclear, roles in spindle fiber formation during mitosis, regulation of apoptosis, and cell motility. The Fenteany laboratory in the Chemistry Department identified a new small molecule, named Locostatin, as a cell migration inhibitor in mammalian cells, with RKIP as its primary molecular target. Dictyostelium discoideum possess two RKIP proteins, RKIP-A and RKIP-B. In order to begin to study the function of RKIP in D. discoideum and its role in cell motility, I created a mutant cell line which lacks a functional RKIP-A gene. In this paper, we show that removal of RKIP-A does not affect vegetative motility, but impairs chemotaxis and development in the presence of drug. Interestingly, RKIP-A knockout mutants appear more resistant to drug effects on vegetative motility than wild-type cells. More research is needed to reconcile these seemingly contrasting results, and to better develop a model for RKIP-A’s role in cell motility.