Oceanography | Vol. 38, No. 2
Flow direction
Higher wind speed
Flow direction
Lower wind speed
Wind wake
Higher turbulence & ocean wake
Physical dispersion of zooplankton
(Late fall – Early spring; Unstratified)
*Seasonally
high wind
speeds
Low turbulence & ocean wake
Nutrient injection
Phytoplankton
Flow direction
Higher wind speed
Flow direction
Lower wind speed
Wind wake
Zooplankton
aggregation
Bottom-up support of zooplankton aggregation
(Late spring – Early fall; Strongly stratified)
*Seasonally
low wind
speeds
Flow direction
Higher wind speed
Flow direction
Lower wind speed
Wind wake
Higher turbulence & ocean wake
Physical dispersion of zooplankton
(Mid-spring, Mid-fall; Weakly stratified)
*Seasonally
moderate
wind speeds
Flow direction
Higher wind speed
Flow direction
Lower wind speed
Wind wake
Top-down predation on zooplankton
(All seasons)
*Seasonally
variable
wind speeds
Scenario A
Scenario B
Scenario C
Scenario D
FIGURE 1. Four potential scenarios of offshore wind turbulence and wake effects on
zooplankton in Nantucket Shoals waters.
zooplankton availability and aggregations at a level
that would impact NARW foraging is an open ques
tion. This scenario may be of most relevance to
NARW ecology because it encompasses the time
frame when NARW are most abundant and actively
foraging in Nantucket Shoals waters. In Scenario B,
OSW effects are strong enough to slightly disrupt
stratification, permitting nutrient injection upward
into the surface layer, but not strong enough to
break down stratification and disperse aggregat
ing zooplankton. These higher nutrient conditions
could enhance primary production and therefore
zooplankton (Carpenter et al., 2016; Floeter et al.,
2017). Scenario C would destabilize stratification
(Carpenter et al., 2016; Miles et al., 2017), which
could potentially disperse zooplankton aggrega
tions similarly to Scenario A. However, current
velocities would need to be high enough, and strat
ification weak enough, for OSW-induced turbu
lence to break down stratification (Carpenter et al.,
2016) and negatively impact zooplankton aggrega
tions. Scenario D involves a more biological mecha
nism whereby high colonization and abundances of
filter feeding invertebrates (e.g., mussels) on turbine
structures facilitate a top-down decrease in zoo
plankton abundance (Perry and Heyman, 2020).
Although this scenario is independent of season,
different physical conditions and levels of turbu
lence will create variable encounter rates and inter
action times between sessile predators and zoo
plankton prey (Prairie et al., 2012).
At the wind farm scale (10–100 km), cumula
tive impacts of multiple turbines may act to reduce
surface current speeds and stratification and cre
ate horizontal shear-induced upwelling and down
welling dipoles that could differentially aggregate
or disaggregate zooplankton (Carpenter et al., 2016;
Sorochan et al., 2021; Christiansen et al., 2023).
Evaluating wind farm-scale impacts on oceano
graphic and zooplankton dynamics will be more
difficult to isolate from regional high natural envi
ronmental variability.
ARE THESE POTENTIAL OSW IMPACTS
ON ZOOPLANKTON GREATER
THAN NATURAL PROCESSES
THAT DRIVE A RANGE OF SCALES
OF SPATIOTEMPORAL VARIABILITY?
Oceanographic conditions on Nantucket Shoals
and on the broader US Northeast shelf are sub
ject to high daily to decadal variability, driven
by local wind conditions, tidal forcing, storm