Alicia Rinaldi-Schuler, a fisheries graduate student at CFOS, volunteered for NGA LTER’s Spring 2018 cruise aboard R/V Sikuliaq. Ordinarily, Alicia studies humpback whales. However, we put her to work sampling zooplankton on the night shift. She filmed the equipment they used (bongo nets, multi-net, and methot net) and the creatures they caught (squid, jellyfish, euphasiids, and fish larvae). Her engaging video summarizes of some of the research that occurs during our cruises.
Category: Field Work
Sikuliaq Cruise, May 2018
In a few short days, 23 scientists and educators will embark on our first LTER cruise aboard the R/V Sikuliaq, April 18 – May 5, 2018. Cruises are integral to our research and we anticipate having three each year – in May, July, and September. This cruise continues decades of time-series of measurements of the spring phytoplankton bloom along the Seward Line. As such, its many objectives center on the physical and biological processes that generate and sustain the spring bloom.
Scientific Purpose
This cruise continues the sampling begun in fall 1997 under the NSF/NOAA NE Pacific GLOBEC program, and supported subsequently a consortium of the North Pacific Research Board (NPRB), the Alaska Ocean Observing System (AOOS), and the Exxon Valdez Oil Spill Trustee Council’s (EVOSTC) Gulf Watch. This is the first cruise as part of the NSF’s Northern Gulf of Alaska Long-term Ecological Program (NGA-LTER). The core scientific purpose of the Seward Line project is to develop an understanding of the response and resiliency of this marine ecosystem to climate variability. This cruise marks the 21st consecutive spring cruise for the Seward Line in the NGA, including Prince William Sound (PWS), and the 48th year of observations at GAK1.
Cruise Objectives
- Determine thermohaline, velocity, light, and oxygen structure of the NGA shelf.
- Determine macro- and micro-nutrient structure of the NGA shelf.
- Determine particle structure and flux rates of the NGA shelf.
- Determine phyto- and microzooplankton composition, biomass distribution, and productivity.
- Determine the vertical and horizontal distribution and abundance of zooplankton species (including macro-jellies).
- Record multi-frequency acoustics for estimation of nekton
- Conduct surveys of seabirds and Marine Mammals
- Conduct shipboard experimental work on phyto- and zooplankton.
- Determine carbonate chemistry (i.e. Ocean Acidification) at selected stations
- Recover and redeploy the GAK1 mooring. Drag for lost mooring at GAK 4 and Gak8i.
- Provide at-sea experience for UAF students.
- Share the experience through outreach/media activities.
Sampling Plan
To achieve the objectives, the cruise will visit four cross-shelf transect lines plus stations within Prince William Sound. At each station, operations will be divided into day and night tasks. In the day, we will perform CTD measurements, bottle sampling, and perform intensive sampling and productivity experiments at selected locations. At night, net tows for zooplankton will catch the critters when they rise in the water column to feed. The shortness of high latitude nights in May will mean more daylight work than nighttime work.
Cruise Planning
Right now, we are planning our next cruise which will be aboard the R/V Sikuliaq in mid-April 2018. There are a lot of elements that must be balanced when planning a cruise. Of course, time, money (including that for processing samples later on shore), and the program objectives all influence the cruise plan, but there are many other facets to consider.
Elements
For one thing, there are logistical elements that limit where the cruise must start and in what order the stations will happen. These include:
- Towing for zooplankton must be done during the day, when they are high enough in the water column to catch
- Productivity experiments must be done during the day when there is sunlight
- Time spent traveling between sampling locations (deadheading) must be minimized
- Equipment and personnel must be delivered to and retrieved from the ship
In addition, we must incorporate elements of previous studies to insure continuity between measurements:
- EcoFOCI sampling stations over the productive sub-marine banks
- Prince William Sound stations (which can’t be in the shipping lanes)
- The timing of Seward Line stations with respect to the Spring Bloom
And unfortunately, bad weather can impact the best made plans.
