Atlantic Silverside

[Field work] To Georgia and back in 48h – a special road trip for science

By H.B.

Somewhere after Richmond, VA, the sun sets and traffic on the I-95 begins moving better. At long last. The four people in the burgundy Dogde Challenger have all already cycled through their driving shifts once and dare an impatient glance at the time left. Still more than 8 hours. More than 8 hours to reach this very special location at the Atlantic coast – Jekyll Island, Georgia. In the trunk of the car a jumble of coolers and a beach seine, buckets, air pumps, and hoses topped with the crumpled witnesses of roadside dining. This is no ordinary road trip.

We, that are Aryn and Nicholas from the Therkildsen lab of Conservation Genetics lab at Cornell University and James and Hannes from the Fish Ecology Lab here at UConn; we went on this road trip to catch live, spawning ripe Atlantic silversides from the southern edge of the species distribution. We then intended to bring these fish back to UConn alive, sample another population from the south shore of Long Island (Patchogue, NY) and produce genetic crosses of these populations.

The broad goal of our expanding collaborative efforts with our geneticist friends from Cornell is the creation of an annotated genome of this species, which will be an important milestone in deepening or understanding of the molecular and genetic responses of organisms to local selection regimes and marine climate change. Given the Atlantic silverside’s ecological importance as an abundant forage fish along the American east coast and it’s rich history as a model organism in evolutionary and ecological studies, the annotated genome is the next logical step.

Even at hindsight, the plan still seems a little insane. But it worked. We indeed managed to catch spawning silversides at the Georgia site and then transported them immediately back to our Rankin Lab, which involved another 17 hours of driving back. After securing samples from Patchogue, we indeed managed to cross single parents from each site to produce full-sib crosses that will later be used to produce what geneticist call a linkage map. Other across and within-population crosses will be used to study gene expression at two different temperatures or raise adults for producing an F2 generation.

The silverside larvae are currently well, feeding, and growing up nicely. We all cross fingers for this enterprise to end in good samples and a step forward for genetic studies on a marine fish.

[New publication] Long-term growth consequences of acidification in Atlantic silversides

October 10th 2016 was a special day for our still young lab here at the University of Connecticut, Today, the ICES Journal of Marine Science published the paper of Chris Murray et al., which is the first of hopefully many publications of our experimental findings originating out of our new laboratory facility here at UConn Avery Point.
Chris and his co-authors report on a large-scale, quantitative rearing experiment on Atlantic silversides eggs, larvae and juveniles under contrasting CO2 conditions that took place between May – September 2015. This novel experiment was designed to address three critical issues lacking in previous ocean acidification research on fish. First, the study spanned several ontogenetic stages. Second, it used very large numbers of individuals to robustly characterize not just potential shifts in mean responses, but also changes in the distribution of length, weight, and condition factor. Third, it provided food at standardized, non-excess levels to prevent that potential metabolic costs of high CO2 exposure could be compensated by survivors simply by eating more food.
Overall the study demonstrated seemingly small but significant growth reductions due to high CO2 and identified a small number of fatty acids that were of significantly different concentrations in high vs. control juveniles.

murray-etal-ijms2016_fig3
Distributions of condition factor per 2mm TL interval for juvenile M.menidia reared for 122dph at control (a) and high CO2 conditions (b). Thick and thin black lines correspond to the 10th/90th and 25th/75th percentiles, respectively, while the red line depicts the median. Data below the 10th and above the 90th percentiles are depicted by black dots. Underlying grey bars show relative frequencies for each 2 mm TL class. Black and grey numbers correspond to numbers of individuals measured for both TL and wW, or for TL only, respectively.
murray-etal-ijms2016_fig4
Cumulative frequency distributions of (a) total length (TL) and (b) wet weight (wW), in juvenile M. menidia reared for 122 dph at control and high CO2 conditions.


Murray, C.S.*, Fuiman, L., and Baumann, H. (2016)
Consequences of elevated CO2 exposure across multiple life stages in a coastal forage fish.
ICES Journal of Marine Science (published online 10 Oct 2016)

[Opportunity] Summer Undergraduate Research Fund (SURF)

Seasonal dynamics in Atlantic Silverside abundance, spawning, and offspring sensitivity to low pH and oxygen

The Summer Undergraduate Research Fund (SURF) offers a summer stipend of up to $3,500 + $500 research. The Evolutionary Fish Ecology Lab offers a variety of suitable topics for undergraduates to work on.
Deadline for applications is January, 20th 2017.

How to apply: http://ugradresearch.uconn.edu/surf/#apply

surf2017

[Collaboration] Nina and Aryn visit from Cornell University

On 19-20 July, our lab temporarily transformed into a genetics laboratory, as Nina Therkildsen and her post-doc Aryn Pierce Wilder visited us from Cornell University (Therkildsen Lab). Their lab also shares the fascination for the Atlantic silverside as a model organism and has set out to eventually assemble the fully annotated genome of this species.

During their visit, they could accompany us for our bi-weekly beach seining in Mumford Cove, where we collected juveniles born this year as well as the last few spawning ripe adults at the end of the season. It was a great summer morning and fun for everyone.

In the lab, Nina and Aryn went on dissecting different types of tissue (muscle, liver, spleen, gills, fins) from a few specimens destined for genetic analyses. In the Rankin lab, we tried a novel procedure on this species, i.e., making haploid embryos by fertilizing strip-spawned eggs with sperm that was UV-radiated before.

Thank you for visiting, Nina and Aryn, and we will see you back in fall, when Nina will give a Friday seminar on 11 November 2016. We’re looking forward to what she will have to report!


[Lab News] The new silverside generation is here!

Rafeed Hussain
By Rafeed Hussain.
On a balmy July 1st the lab returned to Mumford Cove excited at the prospect of seining without dawning waders for the first time this year! Chris and Rafeed conducted the first seine while Jake remained on the beach and photographed the experience. On the second seine, Hannes accompanied Rafeed while Chris weighed the first sample. As expected the species richness and diversity of the seines were less than that of previous excursions. The abundance of silversides was down, while their sex ratio was skewed towards females. Despite a decline in mature silversides, several juveniles were caught, indicating a budding cohort. Perhaps more young silversides will find their way into the lab’s net in the future. Only time will tell!

New-silverside
The first of 2016. On July 1st, the beach seine is catching a few 35 mm silversides – the new generation.

Chris-HB-Mumford-Cove
On 1st July 2016, Chris and Hannes look carefully through the bag of the beach seine to find the first juveniles of this year

[Outreach] A busy year in Mumford Cove

On 13 April, Hannes was invited to the board meeting of the Mumford Cove Association to present a brief update about our groups research activities in and around the cove. It is part of our commitment to public education and outreach to keep property owners informed and maintain good relationships with all parties involved.

The information material below contains graphical summaries of our activities, i.e., measuring water quality parameters continuously with a logging probe and conducting biweekly beach seine surveys for silversides.

To a productive year 2016 in the cove!

Mumford Cove Ass_probe
Mumford Cove Ass_silversides