Copepod grazing and fine‐scale distribution patterns during the Marine Light‐Mixed Layers experiment

Cowles, Timothy J.; Fessenden, Lynne

doi:10.1029/94jc02214

Cited by 38 publications

(18 citation statements)

References 33 publications

(1 reference statement)

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“…Evidence for this comes from both field observations (e.g. Cowles & Fessenden 1995, Montagnes et al 1999, Dekshenieks et al 2001, Alldredge et al 2002, Rines et al 2002 and experimental studies (Speekmann et al 2000, Lougee et al 2002, Bochdansky & Bollens 2004, Clay et al 2004, Ignoffo et al 2005. It is possible that more highly vertically resolved sampling of micro-and nanoplankton in the SFE could reveal greater heterogeneity in vertical distributions than the results presented here based on 2 m depth increments.…”

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confidence: 41%

Vertical distribution of micro- and nanoplankton in the San Francisco Estuary in relation to hydrography and predators

Rollwagen‐Bollens¹,

Bollens²,

Penry³

2006

Aquat. Microb. Ecol.

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Temperate estuaries are characterized by significant seasonal variability in the vertical salinity gradient, which, along with biological factors, may play a role in determining plankton vertical distribution. We examined the vertical distribution of microplankton (20 to 200 µm) and nanoplankton (~5 to 20 µm) in the San Francisco Estuary (SFE) over diel, seasonal and interannual time scales, and assessed the degree to which abiotic (hydrography) and biotic (predation) factors influenced these patterns. We sampled 2 hydrographically-distinct locations within the SFE: San Pablo Bay, a partially-mixed estuary, and South Bay, a lagoonal estuary. We conducted replicate Niskin bottle casts during the day and night at each location on 6 occasions between 1998 and 1999. We also conducted replicate day and night pump sampling for mesozooplankton (>153 µm) on 4 of these dates. The vertical distribution of micro-and nanoplankton was often homogeneous with depth, even under substantially different hydrographic conditions. ANOVA testing of weighted mean depths (WMD) of chlorophyll, major taxa of micro-and nanoplankton, and copepods (factors: location, year, season, time of day) revealed that only the microplankton taxa (specifically ciliates) showed significant differences in vertical distribution over the sampling period. The most significant differences in WMD were observed seasonally. Ciliates and copepods (Acartia spp.) showed significant diel differences in WMD on several occasions, but diel differences were rarely observed among other micro-and nanoplankton. The degree of salinity stratification was never correlated to WMD of any micro-or nanoplankton group, however vertical distributions of heterotrophic loricate and aloricate ciliates and dinoflagellates were often significantly correlated with distributions of chlorophyll and autotrophic nanoflagellates (presumed food), as well as with the vertical distributions of Acartia spp (presumed predators). We conclude that micro-and nanoplankton are often relatively homogeneously distributed with respect to depth in the SFE. However, when micro-and nanoplankton distributions were more heterogeneous, biotic factors had a greater influence on vertical distribution than abiotic factors (stratification) in the SFE.KEY WORDS: Vertical distribution · Microzooplankton · Ciliates · Flagellate · Nanoplankton · Copepods · Estuaries · San Francisco Bay · Stratification Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 44: 2006 ganisms > 200 µm in size), in particular copepods. Diel vertical migration behavior has been observed in many copepod taxa, as a response to light (e.g. Stearns & Forward 1984), to avoid visual predators (e.g. Bollens & Frost 1989), to exploit food resources (e.g. Uchima & Hirano 1988), or to maintain position within a large estuary (e.g. Laprise & Dodson 1994). However, much less is known about the factors influencing the vertical distribution of microplankton (20 to 200 µm) or nanoplankton (2 to 20 µ...

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confidence: 41%

Vertical distribution of micro- and nanoplankton in the San Francisco Estuary in relation to hydrography and predators

Rollwagen‐Bollens¹,

Bollens²,

Penry³

2006

Aquat. Microb. Ecol.

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“…The cell size of the majority of dinoflagellates in the incubation water was much less than the cell size of the dominant diatoms throughout the investigation (see Results). Experiments conducted by Cowles et al (1988) have demonstrated that food selection by copepods can occur on the basis of food quality. Previous studies have shown that egg production is related Table 7.…”

Section: Discussionmentioning

confidence: 99%

“…2 ) goodnessof-fit test (Cowles 1979), as described in detail by Sokal and Rohlf (1969). The frequency distribution of food types in the diet was compared with that in the environment.…”

Section: Calculation Of Grazing Impact-thementioning

confidence: 99%

“…Avoidance of cyanobacteria (Synechococcus spp. ), pelagophytes, and ''green algae'' was observed throughout the study period.The calanoid copepod C. finmarchicus dominates zooplankton biomass in the North Atlantic (Williams et al 1994;Cowles and Fessenden 1995). It is a key biological component of temperate ecosystems and plays an intermediary role between phytoplankton and fisheries variability in this area (Runge 1988).…”

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Selective feeding on natural phytoplankton by Calanus finmarchicus before, during, and after the 1997 spring bloom in the Norwegian Sea

Meyer

Irigoien

Head

et al. 1999

Limnology & Oceanography

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Selective feeding by the calanoid copepod Calanus finmarchicus was investigated during a 3-month study in spring 1997 at a permanent station in the Norwegian Sea (Sta. M, 66ЊN, 02ЊE). Phytoplankton biomass increased from 317 ng chlorophyll a (Chl a) liter Ϫ1 in the prebloom phase to 2,095 ng liter Ϫ1 during the bloom and declined after the bloom to 1,260 ng Chl a liter Ϫ1 . In the prebloom phase, clearance rates of C. finmarchicus females were between 22 and 100 ml copepod Ϫ1 d Ϫ1 , while during the bloom, they ranged from 75 to 92 ml copepod Ϫ1 d Ϫ1, with a decline in the postbloom phase (41 ml copepod Ϫ1 d Ϫ1). After the phytoplankton bloom, the C. finmarchicus population was dominated by copepodid stages CIV and CV, with clearance rates ranging from 7 to 23 ml copepod. Grazing rates of adult females on the phytoplankton standing stock were low in the prebloom phases (5-23 Chl a copepod Ϫ1 d Ϫ1 , respectively), increased during the bloom from 82 to 219 ng Chl a copepod Ϫ1 d Ϫ1 , and declined after the bloom (64 ng Chl a copepod Ϫ1 d Ϫ1 for adult females and 7-27 ng Chl a copepod Ϫ1 d Ϫ1 for copepodid stages CIV and CV). C. finmarchicus showed a selection for diatoms throughout the study period and for dinoflagellates, before and after the spring bloom, despite the low concentration of both groups in the pre-and postbloom phases. During the postbloom period, no differences were observed in the selective feeding behavior of the copepodid stages compared to the adults. The contribution of diatoms to the overall phytoplankton biomass was 8 and 14% in the pre-and postbloom periods, respectively, while dinoflagellates were Յ3%. Haptophytes (dominated by Phaeocystis pouchetii) and cryptophytes were ingested according to their abundance. Avoidance of cyanobacteria (Synechococcus spp.), pelagophytes, and ''green algae'' was observed throughout the study period.The calanoid copepod C. finmarchicus dominates zooplankton biomass in the North Atlantic (Williams et al. 1994;Cowles and Fessenden 1995). It is a key biological component of temperate ecosystems and plays an intermediary role between phytoplankton and fisheries variability in this area (Runge 1988). The Marshall and Orr monograph (1955a), the review by Huntley (1988) and, more recently, Harris (1996) have all considered the feeding biology of Calanus. Much of the earlier literature on copepod feeding behavior focused on size selection of phytoplankton in the field (e.g., Poulet 1973Poulet , 1974Gamble 1978) and more recently, on small-scale interactions between feeding behavior and anatomical structure (Paffenhöfer 1988). From recent investigations (e.g., Støttrup and Jensen 1990; Jónasdóttir 1994; Jónasdóttir et al. 1995;Pond et al. 1996), it has been established that food quality affects copepod production and ultimately, production at higher trophic levels. A detailed understanding of food quality will depend on an appreciation of the role of individual groups, and even species, of phytoplankton in nutrition (Harris 1996). Up to now, little in- Ackn...

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“…, and had the opportunity also to estimate zooplankton grazing from microand mesozooplankton. Mesozooplankton removed between 1-5% of phytoplankton standing stock per day (Cowles et al, 1995). Mesozooplankton are of course unlikely to be included in the sample size typical of primary production incubations.…”

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confidence: 99%

Reply by John Marra

Marra

2004

Limnology & Oceanogr Bull

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7Adding Eq. (1) and Eq. (2) we get G + DB = g (k-g) -1 B o (e (k-g)t -1) + B o (e (k-g)t -1) Eq. (3) Rearranging the right side of Eq. (3) we get k (k-g) -1 B o {e (k-g)t -1} = PP Eq. (4) Eq. (4) describes the primary production (i.e., net primary production according to the terminology of Williams, 1993). For more about the development of this equation, see Moigis (2000).According to Eq. (5), we then have the following relationship PP = G + DB Eq. (5) that shows an observed accumulation of the biomass of phytoplankton (DB) is only a fraction of the primary production. Eq. (5) shows that if G is not taken into consideration, we will obtain an underestimated, and thus wrong, estimate of PP. Hence, the statements given by Karl Banse (in KB02 and reference therein) that the grazing of zooplankton should be taken into consideration when predicting the biomass of phytoplankton should be seen as absolutely valid. JM03 had only correlated DB (DPOC) with his reported 14 C assimilation values. The conclusion that can be drawn from the above is that either JM03´s data should be seen as evidence that the 14 C method gives underestimated PP values, or that in his area of study there was no grazing by zooplankton. JM03 did not comment about grazing studies, but it can be assumed that in any natural waters there is always grazing (as pointed out by Karl Banse).Perhaps the discussions in the 1980's about the validity of the 14 C method, especially in open waters, should be reactivated. Otherwise, the situation that could occur is that productivity studies which have even been made with the clean radiocarbon method in open waters for the last two decades could be in error. , and had the opportunity also to estimate zooplankton grazing from microand mesozooplankton. Mesozooplankton removed between 1-5% of phytoplankton standing stock per day (Cowles et al., 1995). Mesozooplankton are of course unlikely to be included in the sample size typical of primary production incubations. For microzooplankton, the conclusion was that grazing was important, but only during mid-and late-stages of the bloom (Gifford et al., 1995). The activity of microzooplankton in incubations in bottles of 100-300 ml volume is not clear. As I indicated in JM03, grazing can't be assumed important at all places and times. My second point is related to the first. In Figure 1, I have plotted some other of the data from the North Atlantic Bloom Experiment, from Chipman et al. (1993). Along the x-axis is the daytime drawdown of ⌺CO 2 in the mixed layer, observed as the difference between dawn and dusk values from bottle cast samples, and expressed as an areal estimate of primary production. Daytime carbon assimilation based on 14 C uptake in incubation bottles suspended in situ, is plotted on the y-axis. Changes in ⌺CO 2 are probably the most direct estimate of net production we can make and include any heterotrophic Table 1. REFERENCESCitations showing that 14 C uptake closest to net production: processes. The sensitivity for the change in ⌺CO 2 is low; there ar...

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Copepod grazing and fine‐scale distribution patterns during the Marine Light‐Mixed Layers experiment

Cited by 38 publications

References 33 publications

Vertical distribution of micro- and nanoplankton in the San Francisco Estuary in relation to hydrography and predators

Vertical distribution of micro- and nanoplankton in the San Francisco Estuary in relation to hydrography and predators

Selective feeding on natural phytoplankton by Calanus finmarchicus before, during, and after the 1997 spring bloom in the Norwegian Sea

Reply by John Marra

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