in Context the SCotian Shelf - COINAtlantic

plankton are distinctive among ocean biota in that
they derive their energy and structural materials
directly from the environment. They require light
and nutrients (e.g. nitrate, phosphate, silicate) for
their growth. On the Scotian Shelf, diatoms and
dinoflagellates are the largest and most common
phytoplankton (Breeze et al. 2002). Their abundance
is determined by the Shelf’s complex physical
oceanographic features. There is a distinctive
seasonal cycle of growth characterized by a widespread
spring spring “bloom” and a more diffuse
fall bloom. Blooms are a high concentration of
phytoplankton in an area caused by increased reproduction
and resulting in a discoloration of the
water (Garrison 2005). Blooms vary in duration
and scale. Trends in the magnitude and duration
of the spring bloom on the Scotian Shelf indicate
that blooms begin earlier now than they did in
the 1960s and 1970s and are more intense and
longer (Zwanenburg et al. 2006).
Zooplankton are divided into three main categories
on the basis of size: microzooplankton, mesozooplankton,
and macrozooplankton. Zooplankton
are important food sources for higher trophic
levels, including juvenile groundfish, pelagic fish
species and baleen whales (Zwanenburg et al.
2006). The mesozooplankton on the Scotian
Shelf is dominated by copepods. Three species
of copepods, known as Calanus, make up > 70%
of the copepod biomass. Calanus finmarchicus
appears to be a significant link in the food chain
(Zwanenburg et al. 2006) On the Scotian Shelf,
zooplankton levels have been lower in more
recent years than in the 1960s/70s (the reverse
of the phytoplankton trend) and are beginning
to recover from the lows observed in the 1990s
(Harrison et al. 2007).
Plankton research and monitoring has been occurring
on the Scotian Shelf for decades. A more
description of research related to plankton is
provided in Breeze et al. 2002.
Marine Plants
Marine plants are macrophytic marine algae
commonly referred to as seaweeds. The Natural
History of Nova Scotia produced by the Nova
Scotia Museum of Natural History provides a
general overview of marine plants in Nova Scotia.
Seaweeds along the rocky shores of Nova Scotia
can be grouped into the following categories:
green algae, red algae and brown algae. Green
algae need a large amount of light and are generally
found closer to the surface in intertidal or
shallow subtidal areas. Nova Scotia has 82 known
species of green algae. Red algae are able to
grow at greater depths and are generally found
in the intertidal zone, below the low water mark.
Common red algae in Nova Scotia include irish
moss. Brown algae are the dominant seaweeds
and are exclusively marine. Kelp is the largest
of the brown algae and is found in the subtidal
zone. Rockweeds are common in the intertidal
zone (Davis and Browne 1996).
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