Sensitivity of Larval and Juvenile Sand Lance Ammodytes dubius on Stellwagen Bank to Predicted Ocean Warming, Acidification and Deoxygenation (Regional)
|Scott Gallager||Woods Hole Oceanographic Institution||Co-Principal Investigator|
|Les Kaufman||Boston University||Co-Principal Investigator|
|Hannes Baumann||University of Connecticut - Avery Point||Principal Investigator|
|David Wiley||Stellwagen Bank National Marine Sanctuary||Co-Principal Investigator|
|Page Valentine||U.S. Geological Survey||Co-Principal Investigator|
This proposal will quantify the sensitivity of a key forage fish in the Northwest Atlantic to the individual and combined effects of the major factors comprising the ocean climate change syndrome: warming, acidification, and deoxygenation. We will rear embryos of Northern sand lance Ammodytes dubius, obtained by strip-spawning wild adults from the Stellwagen Bank National Marine Sanctuary (SBNMS) through larval and early juvenile stages in a purposebuilt factorial system at different factorial combinations of temperature × CO2 × oxygen.
Our first objective is to quantify individual and combined effects of temperature × CO2 (year 1) and temperature × CO2 × DO (year 2) on A. dubius growth and survival. We hypothesize that warming in combination with high CO2 (low pH) will have additive or synergistically negative effects, whereas the addition of low DO as a third stressor will have stark, synergistically negative effects on all traits.
Our second objective is to characterize the swimming behavior of A. dubius larvae that have been reared under combinations of elevated temperature × CO2. We hypothesize that combined stressors will have synergistically negative effects on the development of larval sensory systems, which express themselves and can thus be quantified as changes in larval swimming behavior.
Our third objective is to take advantage of the rare winter sampling activities for this project to quantify CO2, pH, and DO variability in benthic waters on Stellwagen Bank through bottle collections and short-term sensor deployments. We hypothesize that bottom water pH and DO levels during the sand lance spawning season might be routinely lower than levels in surface waters.
During the sand lance spawning season 2016/17 and 2017/18, we will collect wild ripe A. dubius from the southern SBNMS using a large SEABOSS sediment grab. We successfully tested the method in preliminary trials in November/December 2015, which were part of ongoing sanctuary activities to map sand lance abundance and distribution. We will use the SBNMS vessel ‘R/V Auk’ to collect specimens during five cruises each year throughout the spawning season (Nov – Feb) and transport at least 30 ripe individuals per sex live to our laboratory facility (Rankin Laboratory, UConn Marine Sciences, Avery Point Campus). Adults will be strip-spawned to obtain fertilized embryos, a method that has been used successfully in the smaller, more delicate A. americanus. One hundred newly fertilized embryos will be placed in each of six replicate containers (20L) per treatment and then reared at optimal light, salinity, and ad libitum feeding conditions post hatch. In year 1 (Experiment 1), fertilized embryos will be reared in a 3 × 3 factorial design using three temperatures (5, 7, 10°C) × three CO2 levels (8.1 pH ~400 μatm; 7.8 pH, ~1,000 μatm; 7.5 pH, ~2,000 μatm) in a total of nine treatments. In year 2 (Experiment 2), fertilized embryos will be reared in a 2 × 2 × 2 factorial design using two temperatures (5, 10°C) × two CO2 (~400 μatm; ~2,000 μatm) and two DO levels (8 mg L-1, low 4 mg L-1) in a total of eight treatments. All rearing experiments will be conducted in a purpose-built system, where pH and DO will be controlled via a fully automated sensing routines that enable mixing air, N2, and CO2 in nine separate recirculating units. Discrete water samples will be chemically analyzed for alkalinity and pH at least twice per experiment (other parameters calculated via CO2SYS). We will quantify hatching time and success, post-hatch survival (larvae, early juvenile), larval and juvenile length, and condition. For our second objective, we will transport larvae to the Woods Hole Oceanographic Plankton Behavior Facility in Gallager’s lab. This time-tried set-up consisting of stereo-cameras and state-of-the art post-processing routines will enable us to track larvae in real-time to quantitatively assess the potentially different swimming behavior of larvae reared at different tempreature x CO2 conditions. Specifically, we will (i) assess larval swimming behavior in the presence of an artificial thermocline (thermal response), (ii) quantify larval depth distribution throughout the tubes (pressure), (iii) larval light sensitivity (directional lighting and timing) and orientation (gravity). Our third objective is to take advantage of the rare winter sampling activities for this project to quantify pCO2, pH, and DO variability in benthic waters on Stellwagen Bank through bottle collections and short-term sensor deployments. We hypothesize that bottom water pH and DO levels during the sand lance spawning season might be routinely lower than levels in surface waters.
Anthropogenic warming, acidification, and deoxygenation are together affecting marine ecosystems, yet the combined effects of these stressors on marine species remain poorly understood. The major concern is that their combined impact could be greater than the sum of each stressor, i.e., synergistically negative, but these crucial empirical data are currently lacking for all but a very few model species. This knowledge gap currently limits our ability to predict the nature and direction of impending changes in marine ecosystems. In temperate North-Atlantic ecosystems, sand lances (Ammodytes spp.) are key forage fish. In the Stellwagen Bank National Marine Sanctuary, their presence is a major reason for the seasonal abundance of iconic predators such as bluefin tuna, cod, sea birds, and humpback whales. Despite their importance for the ecosystem, there are no empirical data on the sensitivity of A. dubius to the threats of warming, acidification, and hypoxia - not individually, and not in combination. No study to date has specifically evaluated the vulnerability of multiple life stages of fish to multiple stressors. Beyond collecting new data on an important, previously untested species, however, our approach has further scientific merit, because sand lance occupies a different habitat (coastal shelf) and has a different spawning season (winter) than all previously studied fish species. This sets up a so far lacking, but potentially highly insightful contrast between the sensitivity of nearshore forage fish species and more shelf-based species like sand lance. It has been hypothesized but never explicitly tested that the sensitivity of marine organisms to elevated CO2 levels increases with decreasing environmental variability, i.e., from nearshore to ocean shelf to open ocean.
Our research will benefit resource managers and coastal communities that dependent directly on indirectly on this marine resource (e.g., by recreational fishing, whale watching etc). Importantly, if sand lance are found to be particularly sensitive to acidification and/or warming and/or deoxygenation, this ought to be strongly communicated to those who currently advocate for starting a commercial fishery for this species. The project will partially fund and train a graduate student, who will make this a central topic of his/her PhD thesis. Apart from disseminating our findings in leading international journals of biological oceanography and climate change, we have put together an ambitious outreach plan including: (i) contributions to popular scientific outlets (e.g. Wrack Lines), talks, presentations to students, stakeholders, and scientists, (i) a multipronged website presence to make available events, data, stories, and photographic documentation. We will incorporate highschool and undergraduate participation into our experiments and field surveys. As a key forage species that structures marine food webs, information on sand lance sensitivity to marine climate change is essential for the planning of resilient coastal economies.
Our proposal directly responds to NECAN research area 1 (Species-response studies of OA impacts on critical life stages of commercially important species of shellfish and finfish) and is further responsive to the call for multi-stressor research encompassing multiple life stages of critical resources (research area 2 (Multiple life stage and/or multi-generational studies…). Hence, our results will encourage the adoption of sustainable marine policies by providing scientifically sound, evidence-based information for managers and an informed public.