Life in the Ocean. Bloomin’ Plankton! Boston Globe, June 2005

Nutrient Supply to Photic Zone nutrient-rich deep water nutrient-depleted surface water 1. Stable stratification (Doesn’t work) 2. Storm or density-induced mixing plankton bloom nutrient-rich deep water 3. Wind-driven upwelling wind nutrient-rich deep water plankton bloom 4. River runoff to ocean river plankton bloom photic zone Plankton need nutrients. This is how they get ‘em…

Phytoplankton: Major Groups Bacillariophyceae (diatoms) About 100 µm across diatoms, coccolithophorids, dinoflagellates opal (SiO 2 ), calcite (CaCO 3 ), organic-w alled, (Mineral composition keyed to group by color)

Coccolithophorids: Calcareous Phytoplankton Emiliania huxleyi Discosphaera Both about 250 µm across Calcareous nannoplankton (arose perhaps 210 million years ago in oceans) Coccospheres shown note individual coccoliths widespread in today’s oceans, especially in temperate zone “spring blooms” and are main group in central gyre regions prefer low to moderate nutrient supply

Dinoflagellates flagellum Arose some 350 million years ago Prefer high levels of nutrients Eutrophic regions Often have “resting cysts” What advantage? Problem plankton? Red Tides: massive “blooms” of dinoflagellates Some, like Gymnodinium and Gonyaulax, secrete neurotoxins Competitive strategy But causes problems ultimately for humans

Seasonal Change in Phytoplankton Abundance l Seasonal changes in light (sun angle, hours of daylight) l Seasonal changes in water-column stability (more stability, less nutrients mixed to surface) l Predator/prey interactions (changes in “grazing” by zooplankton)

Seasonal Changes in Phytoplankton Biomass “Changes in latitude, changes in attitude” --what are key factors determining seasonal patterns of biomass in tropics vs. temperate vs. polar? --think! What determines light and nutrient availability in each environment? Figure 13.7

Whale Feeding in the Bering and Chukchi Seas Krill and amphipods (zooplankton, benthos) A coccolithophorid bloom in April over the Bering Shelf

Baleen Whales Gray whales are baleen whales (sieving food with baleen). They are the only whale known to routinely feed on the bottom. They migrate from Baja California to feed in summer in Bering Sea Sediment plumes shed by rising gray whales Sonar image of feeding “pits” on bottom

Other factors of importance in phytoplankton ecology Growth rate and survival depend on: a) temperature reproduction vs. growth optimum b) salinity Plankton are “isotonic” c) predator-prey relationships –zooplankton “cropping” Phytoplankton must float passively and remain in photic zone. Temperature and salinity determine density of water. Plankton must have same density as water they do best in in order to float.

How do phytoplankton acquire nutrients and eliminate waste? Osmosis (passive diffusion of molecules in the direction of chemical gradients (e.g., from high to low concentration) works in organism’s favor. Nutrients diffuse into cell as they are depleted Waste products diffuse out of cell as they build up

phytoplankton A colony of Chaetoceros, a diatom. These can be 1-2 mm long. Chloroplasts can migrate in and out along spines!

Plankton Form and Function Maximize surface area and drag, minimize density Spinose planktonic foraminifer (zooplankton) spines Streaming protoplasm shell with photosymbionts The shell at center is about 250 µm across

Phytoplankton Growth and Reproduction Example for marine diatoms: populations double, on average, each day How is this accomplished? Coscinodiscus Each about 63 µm across

Diatom Reproduction by Fission cell division vs. auxospore production Unequal sized valves one line becomes smaller and smaller until it is signaled for auxospore production, which generates a new diatom of normal size

Overall phytoplankton production (total biomass) is greatest for open ocean (pelagic) regions. However, greater than 99% of oceanic fish production occurs in about 10% of ocean area (shelves and upwelling zones). Why? Because: The production of organic matter (by phytoplankton) is highest per unit area in shelves and upwelling zones Food chains are shorter (fewer trophic levels), so less overall loss of energy. Efficiency is greater!!

HARMFUL ALGAL BLOOMS The most common threat to shellfish- eating humans is Paralytic Shellfish Poisoning, or PSP. PSP can result from eathing clams, mussels, or other shellfish that have ingested algae laden with a family of poisons called saxitoxins. Saxitoxins act like corks, blocking the movement of sodium through the nerves and thereby deactivating them. The result is paralysis - only your heart, which runs on a separate system, and your brain remain functional. Eventually you suffocate and die. There is no known antidote for Paralytic Shellfish Poisoning.

Boston Globe, June 2005

Harmful Algal Blooms One expert points out, there are many folkloric "rules" among West Coasters about how to detect toxins in shellfish. He cautions against all of them. "Don't believe the common expression that shellfish are safe to eat in months with the letter R in them - blooms can happen any time of the year." In 1999, for example, PSP outbreaks on the West Coast lingered well into October and November. And nibbling on a single clam to see if your lips tingle before chowing down on more - another commonly believed old wives' tale - is not just bad advice; it could spell disaster.

Harmful Algal Blooms and Aquaculture Naylor, SCIENCE, 313; 8 SEPTEMBER2006 The burgeoning business of aquaculture, or fish farming, is also a growing source of nutrients for harmful blooms. The fish in enclosed fish farms produce a huge amount of waste, which in turn feeds the blooms. Recently, an epidemic of toxic blooms spurred Scotland to ban scallop fishing from 8,000 square miles of coastal waters; the blooms were blamed on waste generated by salmon farms. According to the Suzuki Institute, fish farms off the coast of B.C. dump sewage equivalent to that generated by a city of 500,000 people into coastal coves every day. The US recently introduced legislation to promote offshore aquaculture.

Is There Remediation of HABs? l Perhaps--one strategy is to spray fine clay over surface l The surfaces of the clay (only one type, called montmorillonite, works) attracts algal cells and settles to the bottom thus sweeping out the HAB for awhile