Coagulation is the formation of large particles 'from multiple collisions of smaller ones. Because larger particles fall faster than smaller ones, coagulation can be important in accelerating the export of organic matter from the ocean's surface to the deep sea and has the potential to limit phytoplankton populations. We have developed a model of an algal bloom that includes nutrient and light limitation of algal growth rate and coagulation of single algal cells. The results show two effects of coagulation on the growth model. Loss of dividing cells to coagulating particles can occur when algal cells are growing at a fairly constant rate, placing a cap on the concentrations that algae can achieve. The second effect is enhancement of vertical particle flux from the surface mixed layer in aggregates. This enhanced transport moves algal biomass from the surface mixed layer over shorter periods at rates far greater than those associated with settling of single cells. For example, half the material associated with a bloom of 2-pm-radius algae, which would take 350 d to settle out as isolated cells, took 42 d as aggregates. Aggregation was not limited to the large algae, although the rate was slower for the smaller ones. Coagulation was enhanced by higher initial nutrient concentrations, deeper mixed layers, and higher shear rates. Vertical transport associated with aggregation has the potential to be an important mechanism for removing biological material from eutrophic regions.

Atlantic cod (Gadus morhua) larvae were reared under various feeding environments to assess their lipid class composition and survival during development. Lipids were assessed in individual larvae. Triacylglycerol (TAG), phospholipids (PL), and defatted dry weight (DDW) all fell during yolk absorption. TAG increased after initiation of exogenous feeding in different feeding treatments but did not increase in starved larvae. The percentage of individuals greater than 8 d old with high TAG or PL increased with increasing prey concentration. Survivorship was low in all feeding trials, but groups with a larger percentage of individuals in poor condition tended to exhibit a higher risk of death. We suggest a condition index based on a discriminant function using TAG, PL, and DDW. We assessed the condition of field-collected larvae based on this index.

We compared shoreline seines with fyke nets in terms of their ability to sample fish species in the littoral zone of 22 floodplain lakes of the White River, Arkansas. Lakes ranged in size from less than 0.5 to 51.0 ha. Most contained large amounts of coarse woody debris within the littoral zone, thus making seining in shallow areas difficult. We sampled large lakes (.2 ha) using three fyke nets; small lakes (,2 ha) were sampled using two fyke nets. Fyke nets were set for 24 h. Large lakes were sampled with an average of 11 seine hauls/ lake and small lakes were sampled with an average of 3 seine hauls/lake, but exact shoreline seining effort varied among lakes depending on the amount of open shoreline. Fyke nets collected more fish and produced greater species richness and diversity measures than did seining. Species evenness was similar for the two gear types. Two species were unique to seine samples, whereas 13 species and 3 families were unique to fyke-net samples. Although fyke nets collected more fish and more species than did shoreline seines, neither gear collected all the species present in the littoral zone of floodplain lakes. These results confirm the need for a multiple-gear approach to fully characterize the littoral fish assemblages in floodplain lakes.

Gut contents were obtained from 1406 cod larvae from 94 stations in seven water masses related to a gyre around Western Bank, Scotian Shelf, 22 November–16 December 1992. Initial samples were from: well‐mixed water over the bank crest (CW); a surrounding convergent FRONT; relatively cold, fresh water (CFW) largely east of CW; warmer, salty water (WSW) west of CW and FRONT. After a storm on 3–6 December, samples were from CW and CFW displaced south‐east on the bank and, after further winds 11–12 December, from CW displaced north‐west off the bank. Zooplankton biomass (300–333 μm mesh, mostly Calanus copepodids) did not differ among water masses, but larval concentrations were significantly higher in FRONT than elsewhere. The small‐copepod diets of larvae varied among water masses, partly attributable to larval growth during the sampling period. Numbers of prey in guts, and indices of fullness and digestion, varied among water masses. More reliably, after ANCOVAs significant independent variables were: overwhelmingly time of day (maximum prey numbers and fullness at ∼19:00) and larval size; water mass; weaker interactions of the above among themselves and with sample depth and date; a very weak negative turbulence‐index effect on gut prey numbers in depth‐stratified samples. After ANCOVAs, larvae from prestorm CW had significantly higher prey numbers and fullness than did those from FRONT, WSW, and CFW. Larvae in CFW were significantly fuller when sampled closer to sites of former CW after the storm. Although numbers of prey in larvae advected off the bank in CW decreased significantly, prey averaged larger, so that gut fullness did not decrease. We conclude that larvae were best fed in the `centre' of the Western Bank gyre, but not greatly affected by subsequent displacement off the bank.

A previously reported protocol for culture of larval sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) to fingerling size in tanks involved an initial feeding of rotifers for several days before the larvae were weaned to nauplii of brine shrimp Artemia spp. and prepared feed. Maintaining rotifer cultures requires space, time, equipment, supplies, and trained culturists. The rotifer cultures are often unstable, which increases risk of poor sunshine bass fingerling production in tanks. Elimination of the use of rotifers would greatly enhance the feasibility of reliable tank culture of fingerlings and should reduce production cost. This experiment compared three treatments with three replicates per treatment. In one treatment, larvae were initially fed rotifers Brachionus plicatilis and then were weaned to brine shrimp nauplii (0.48 × 0.19 mm). In a second treatment, larvae were fed brine shrimp nauplii throughout the experiment. In a third treatment, larvae were fed microcyst brine shrimp nauplii (0.43 × 0.18 mm) for the entire experiment. At 4 d posthatch (dph), sunshine bass larvae were stocked into 100‐L tanks at 75 larvae/L. Larvae were fed according to the three treatments to 14 dph. Survival was significantly higher for larvae fed rotifers plus brine shrimp nauplii and for larvae fed microcyst brine shrimp nauplii (93.6% and 37.9%, respectively) than for larvae fed only brine shrimp nauplii (4.3%). Larvae (7.13 mm standard length [SL]) that were fed rotifers plus brine shrimp nauplii and larvae (7.26 mm SL) that were fed microcyst nauplii were significantly longer than those (6.86 mm SL) fed brine shrimp nauplii. This experiment is the first time that sunshine bass have been cultured to 14 dph on brine shrimp nauplii without rotifers at first feeding.