Adventures in the Gulf of Maine — Part 2

This is the second of three (or more?) posts about our field campaign in the Gulf of Maine during Spring/Summer 2023.

By the beginning of June, we had completed our first of three cruises and were feeling pretty good. The goals was to collect samples from the nearby Gulf of Maine that would allow us to assess the prevalence of mixotrophy in the field, the extent to which copepods were feeding on potential mixotrophs, and the reproductive condition of two copepod species. I was excited to have the opportunity to bring some early career researchers into the field with us and to round out the data set.

Unfortunately, the weather gods did NOT smile on us. Our next cruise was delayed three times due to weather and ship maintenance issues. We finally ventured out on June 26 in rain, fog and rough seas (I cheated on the “featured image”…it was taken in July). As always, the crew of the R/V Gulf Challenger was very safety conscious – they even added glow sticks to our work vests as an extra precaution due to the weather. I had taken Dramamine, but let’s just say it proved insufficient…

We reached our first station around 8:30 pm, collected a water column profile using the CTD, and conducted a series of CTD casts to sample water for DNA sequencing, mixotrophy incubations, and experiments with live copepods. We finished water sampling a little after 10 pm and were ready to tow for zooplankton. The weather had continued to deteriorate, and due to ongoing ship maintenance, the system for keeping the net aligned on the winch was not ideal. For safety reasons, we had to give up on collecting zooplankton from the WBTS station. We decided to move directly to our final station, which was predicted to be a little calmer. At the inshore station, we had more success. We were able to collect both water and zooplankton, but it somehow felt underwhelming to come back with less than a full set of three stations sampled.

Back onshore, we relocated to the Judd Gregg Marine Research Complex to set up copepod egg production experiments. As we had seen previously, Centropages typicus were abundant at this site, but Calanus finmarchicus were relatively rare. We saw a broad mixture of C. typicus stages, but most of the C. finmarchicus that we saw were copepodites (juveniles). This made sense…back in April we were seeing adults producing the first generation, but now we were seeing maturation and a mix of stages. The bad news was that we could only set up a few C. finmarchicus egg production experiments, but the good news was that we could bring home some C. finmarchicus juveniles for a side project.

Overall the June cruise was a mixed bag, but we still had July sampling on the horizon.