Dj. Lonsdale et al., FOOD-WEB INTERACTIONS IN THE PLANKTON OF LONG-ISLAND BAYS, WITH PRELIMINARY-OBSERVATIONS ON BROWN TIDE EFFECTS, Marine ecology. Progress series, 134(1-3), 1996, pp. 247-263
We examined the relative importance of phytoplankton and ciliates as p
rey for metazoan zooplankton, and the role of predation in regulating
ciliate populations in 2 Long Island (USA) bays. Depth-integrated prim
ary production (mg C m(-2) h(-1)) was dominated by nannoplankton < 5 m
u m in diameter throughout the year, ranging from > 95% of total produ
ction in mid-summer to an average of about 60% in winter and early spr
ing. Predator exclusion and addition experiments conducted in microcos
ms showed that the mortality coefficient of ciliates (d(-1)) from zoop
lankton predation was higher when larger phytoplankton (> 10 mu m) con
tributed less to total primary productivity. For adult copepods, an in
crease in the percentage ciliate contribution compared to phytoplankto
n contribution to total carbon intake also coincided with the higher p
ercentages of small microalgal production. Egg production rates of Aca
rtia spp. were positively correlated to the net growth coefficient of
ciliates. In contrast, micrometazoa routinely obtained > 70% of their
total carbon ration from phytoplankton, and at times during spring and
summer, removed 23 to 52% of the total depth-integrated primary produ
ction. In addition to protozoa, we suggest that micrometazoa, particul
arly copepod nauplii, may serve as a trophic link between phytoplankto
n and mesozooplankton in Long Island bays.