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 August

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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 August:

  • By August, diatoms have consumed just about all the nitrate and other nutrients brought up toward the surface by upwelling. Thus, fall brings some of the lowest nutrient concentrations of the year to the waters offshore of Monterey Bay
  • August sees a marked decline in populations of centric diatoms but secondary blooms of pennate diatoms (which reach maximum average concentrations in August), dinoflagellates, and smaller phytoplankton (picoplankton). These late summer algae thrive in a more stable water column, and can live off of urea and ammonia released by zooplankton and other animals that are abundant in coastal waters in summer.
  • Oceanic water typically brings new open ocean animals such as albacore tuna and blue sharks, as well as lots of jellies, including moon jellies, egg-yolk jellies, drifting marine snails known as heteropods and pteropods, and salps (basically sea-squirts that swim around the open ocean feeding on algae).
  • Changes in the dominant plankton species lead to transitory, seasonal communities with their own food webs (e.g. dinoflagellates -> salps -> Nanomia siphonophores -> jellies -> Mola mola and leatherback sea turtles).
  • Intrusions of oceanic water can sometimes carry oceanic species of zooplankton, as well as drifting larvae toward shore. But if large tongues of water sweep into Monterey Bay, they can flush all the surface waters out of the bay, carrying drifting larvae out to sea.
  • Krill swarms--fast food for whales on the move: Huge swarms of adult krill feed on late diatom blooms (especially over the shelf break) and provide food for migrating humpback and blue whales.
  • Albacore tuna move up the coast with the warmer (15-20 deg C) water along the seaward edge of the California Current. They sometimes come toward shore to feed on fish, krill, and squid.
  • Like albacore tuna, blue sharks also follow the warm water up the coast in late summer and fall, feeding on market squid, krill (esp. T. spinifera), anchovies, and hake.
  • Fall sometimes sees an influx of small "by-the-wind sailors" (Velella velella - a colonial jelly), which have spent the last few months maturing in deep water, but eventually rise up to the surface to feed (and collect sunlight for algae that grow within their bodies).
  • Spring-spawning deep-water rockfish (eg. aurora rockfish, stripe-tail rockfish, cowcod) begin to settle down toward the muddy seafloor of the outer continental shelf.
  • Fishing catches of deep-water rockfish, including yellowtail rockfish, rosy rockfish, greenspotted rockfish, and starry rockfish, typically peak between JULY and SEPTEMBER.
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