Seasons in the Sea - A month-by-month guide to Central California sea life

Section contents:

Mackerel school: Image credit-Kip Evans

The open ocean

in September

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Diver-at-work symbol (c) Kim Fulton-Bennett This page under construction.
Here are some of the topics that will be covered in this chapter. More text and images will eventually be added to this section. Thank you for your patience.

Open-ocean events in September:

  • The clear, blue water of the oceanic season is clear and blue because it contains almost no microscopic algae. Diatoms, in particular, become much less abundant as the month of September progresses.
  • The clear, blue oceanic water, if it contains any algae, typically harbors a infintesimal microscopic algae called picoplankton (only 1/20 to 1/100 the size of spring-bloom diatoms). Some picoplankton are much better than diatoms at surviving in water that contains very low concentrations of nutrients (e.g. nitrate and iron).
  • One type of microscopic algae called dinoflagellates may continue to grow in warm protected coastal areas, such as the northeast corner of Monterey Bay. From late September to November, such protected areas occasionally become "incubators" for dinoflagellate blooms ("red-tides") that can last for weeks and spread over large areas. [link to sidebar on red-tides and toxic algal blooms]
  • As microscopic algae (phytoplankton) become scarce, so do many of the tiny animals (zooplanton) that feed on these algae.
  • Open-ocean jellies and the sea turtles that feed on them arrive when pulses of clear, blue, oceanic water approach the coast. Farther from shore, warm-water fish such as albacore tuna migrate northward along the coast.
  • Krill typically remain abundant in September, and only begin to decline in October, toward the end of the Oceanic Season (so do populations of blue whales and other krill-eating mammals and seabirds).
  • Schools of anchovies, market squid, and juvenile rockfish begin to disperse, typically heading offshore or into deeper water.
  • In September and October, juvenile ("young of the year") rockfish (e.g. green-striped rockfish, striped-tail rockfish, and cowcod), which have been drifting and swimming around as zooplankton for several months, settle onto the muddy seafloor, especially along the outer part of the continental shelf, in water 250-350 feet deep.
  • White croaker (Genyonemus lineatus) migrate from deep water to within a few miles of shore, where they will remain until June of the following year. White croaker spend summers (June through August), at depths down to 100 feet (the inner continental shelf). The rest of the year (September through May) croakers spend spawning and feeding closer to shore, especially in protected areas such as the shallow waters of Monterey Bay. In either case, they do some scavenging of detritus, as well as and hunting a variety of seafloor animals including small fishes such as gobies, squids [market squid?], shrimps, octopuses, worms, and crabs.
  • Bottom-fish populations in Monterey Bay reach a yearly peak in August and September (as do the number of different fish species present).
  • Giant pacific octopus (Enteroctopus dofleini) are believed to mate in fall. Mating is tricky, since these octopus are often cannibalistic. If a male octopus unknowingly approaches another male, they may fight and the smaller one will often be killed and eaten. Even mating octopus keep eachother at arm's length, so to speak, with males using a specialized tentacle to transfer a sperm packet to the female, before gliding quickly away. Within a few days to a month after mating, the female lays tens of thousands of eggs the size of rice grains beneath an overhanging rock then broods them for four to six months, until they hatch the following spring.
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