Regions of freshwater influence (ROFIs) - Introduction to the Physical and Biological Oceanography of Shelf Seas - page 292

(a)

Delaware
Bay

39°N

1

2

3

4

38°N

75°W

(b)

100

100 Stage I 100

Stage II Stage III

50

50 50

1 2 3 4 1 2 3 4 1 2 3 4

100

100

Stage IV Stage V

50

50

1 2 34

1 2 34

Station number

(c)

100

Surface
Bottom

50

I II III IV V

Larval stage

Figure 9.14 Ontogenic changes in the distribution of fiddler crab larvae within the ROFI at
the entrance to Delaware Bay. (a) The 4 sampling stations from the Bay mouth seaward.
(b) Changes in the location of larval stages, expressed as relative abundance of each stage at
each sampling position. (c) Changes in the vertical distributions of the different larval stages.
Adapted from Epifanio et al., 1988 , with permission from Inter-Research.

Alongshore transport of phytoplankton has also been linked to coastal buoyancy
currents, often with a focus on nuisance species (e.g. Franks and Anderson, 1992 ).
A dramatic example is that of the odyssey thought to be undertaken by the dinofla-
gellate Prorocentrum mariae-lebouriae in Chesapeake Bay, shown in a series of along-
Bay surveys of salinity and Prorocentrum cell numbers in Fig. 9.15 . The surface
bloom of Prorocentrum reaches the mouth of the Bay in winter, driven by the
seaward (southward) surface flow ( Fig. 9.15a ). Circulation between the mouth of
the Bay and the adjacent shelf, combined with weak stratification, leads to the cells
being distributed through the water column. Figure 9.15b shows that, as stratification