Archivos de Diario para octubre 2019

13 de octubre de 2019

Final Species List and Discussion for Andrew Cohen's September 14th and October 5th "Critter Walk."

Again many thanks to Dr. Cohen!

Critter list for Lake Merritt walks on 9/14/2019 and 10/5/2019
Duck Ponds to Boathouse Docks

  • indicates that the species is in
    (N) indicates a native species and (I) an introduced non-native species.

Sponges (Porifera)
Halichondra bowerbanki (yellow sponge, crust-of-bread sponge) (I) on dock sides (9/14 & 10/5)

Anemones (Anthozoa)
Diadumene lineata* (I) on rocks & dock sides (originally named Sagartia luciae); green column, sometimes with vertical orange lines on column, yellowish tentacles (9/14 & 10/5)
Diadumene leucolena (I) with vertical double white lines on column; on dock sides & rope (9/14)
(The anemone I said was a Metridium on 9/14 might have been D. leucolena.)

Sea worms (Polychaeta)
Ficopomatus enigmatica* (I) (tube worms on dock sides and on rocks below upper zone of barnacles) (9/14 & 10/5)
Terebellid worm (Spaghetti worm) in clay tube, collected at docks (10/5)

Snails & Sea Slugs (Gastropoda)
Tritia obsoleta* Atlantic Mudsnail (I) on mud and rocks (9/14 & 10/5; egg cases on 9/14 only)ly)
Urosalpinx cinerea* Atlantic Oyster Drill (I) snails with yellow or orange, ocassionally white, shells, on rocks and dock sides (9/14 & 10/5; vase-shaped egg cases found under rocks on 10/5)
Assiminea californica (N) tiny brown snail on underside of rocks (9/14) (there are pictures of Assiminea on the Myosotella myosotis page at
Haminoea japonica (I) slugs, kidney-shaped gelatinous egg masses with yellow eggs, and a few delicate, transparent internal shells found on rocks, dock sides, undersides of rocks (9/14 & 10/5; egg masses abundant and slugs fairly common on seaweed on 10/5)

Clams & Mussels (Bivalvia)
Geukensia demissa* Atlantic Ribbed Horsemussel (I) shells on mud, live mussels on rocks and undersides of rocks (9/14 & 10/5)
Mytilus trossulus (N), Mytilus galloprovincialis (I), or hybrids Bay Mussel or Blue Mussel - on rocks, dock sides, ropes, undersides of rocks (9/14 & 10/5)
Arcuatula senhousia* Green Bagmussel or Asian Date Mussel (I) on rocks, dock sides, underside of rocks (9/14; empty shells and parts of shells found among Mytilus byssal threads on 10/5)
Mya arenaria* Eastern Softshell Clam (I) shells common on mud (9/14 & 10/5; small live clams found among Mytilus byssal threads on 10/5). (Cryptomya californica, a native species in the same family that also has a chondrophore—a shelf-like structure that forms the hinge on the left valve—discussed in connection with its shallow pallial sinus and association with burrows of other animals).
Ruditapes philippinarum* Japanese Littleneck Clam, Manila Clam (I) someone brought me one empty shell near the end of the walk on 9/14
Probably in the genus Nebalia or an allied genus - Katie Noonan found one near the docks. (9/14)

Barnacles (Cirripedia)
Amphibalanus amphitrite* (I) on rocks (9/14 & 10/5)

Rolly-pollies, sowbugs (Isopoda)
Sphaeroma quoianum (I) the larger isopod, among barnacles and in empty barnacle shells on the sides of large rocks (on 10/5) and on undersides of smaller rocks (9/14 & 10/5); usually with a double row of 4 bumps on its tail segment; this spices sticks out the small limbs alongside its tail segment ("uropods") when it rolls up into a ball
Gnorimosphaeroma oregonense (N) the smaller isopod, on the undersides of rocks; often with a broad, gray stripe along its back; does not stick out the small limbs alongside its tail segment when it rolls up into a ball (9/14 & 10/5)
(Discussed: Iais californica (I) commensal on the underside of Sphaeroma quoianum)

Scuds, Sand Fleas (Amphipoda)
Unidentified amphipod in the suborder Gammaridea - underside of a rock (9/14)
Skeleton shrimp - on dock sides; these are highly modified amphipods in the family Caprellidae (9/14 & 10/5)

Crabs & Shrimp (Decapoda)
Pagarus sp. Hermit Crab (N) in an Oyster Drill shell, on rocks (9/14)
Palaemon macrodactylus (I) one found among dock fouling; Asian shrimp thought to be from Korea based on its discovery in the Bay around the time of the Korean War (10/5)

Conopeum tenuissum? - small colonies of an encrusting, membraniporine bryozoan that may be this species, on organisms attached to dock sides (9/14 & 10/5)
unidentified arborescent (branching, bushy) cheilostome bryozoan - small colonies on dock sides (9/14 & 10/5)

Sea Squirts (Tunicata)
Molgula manhattensis (I) very abundant on the dock sides (9/14 & 10/5)
Ciona savignyi (I) I saw one that was dound on the side of the docks (10/5)

Tridentiger sp. Goby (I) on mud (10/5)

Marsh Plants (I've listed the typical zonation pattern, but this may be less apparent in the small bits of recently-created brackish marsh at Lake Merritt)
Baccharis pilularis Coyote Bush (N) - high marsh/dry land transition (9/14 & 10/5)
Grindelia stricta Gumplant (N) - high marsh and slough levees (9/14 & 10/5)
Distichlis spicata Salt Grass (N) - high marsh (9/14 & 10/5)
Limonium Marsh Rosemary or Sea Lavendar (N) - high marsh (9/14)
Salsola soda Mediterranean Saltwort (I) - high marsh (9/14 & 10/5)
Jaumea carnosa (N) - marsh plain (9/14 & 10/5)
Sarcocornia pacifica (formerly Salicornia virginica) Pickleweed (N) - marsh plain (9/14 & 10/5)
Frankenia salina Alkali Heath (N) - marsh plain (9/14 & 10/5)

Birds of Note
Canada Geese and Mallard Ducks (9/14 & 10/5) On 10/5 discussed the biological, morphological, genetic and ecological species concepts; on 9/14 & 10/5 discussed Dave Wilcove's concept of Canadoids and Mallardoids, and Dave Covel's introduction of Canada Geese to Lake Merritt.
Double-crested Cormorants (9/14 & 10/5) On 9/14 we had the lovely experience of watching a comorant swim around underwater in front of us searching for a snack as gobies scattered before him; and discussed observations in the 1940's of regular "team fishing" by enormous flocks of comorants in San Francisco Bay between Berkeley and Emeryville.
Great Egret (9/14 & 10/5)
White Pelicans (9/14)
Coot (10/5)

Some Other Discussions
California Ridgway's Rail (former name: California Clapper Rail, which I still tend to use) interactions with the Atlantic Ribbed Horsemussel. (9/14 & 10/5)
The interactions of Saltmarsh Song Sparrows and Marsh Wrens in non-native cordgrass marsh. (9/14)
Clam shell anatomy; the size of the pallial sinus as an indicator of a clam's ecology (depth in the mud and types of predators); and why the native clam Cryptomya californica is typically found at depth despite its small pallial sinus. (9/14 & 10/5)
The recent and ongoing extirpation of the native mudshrimp by a non-native bobyrid isopod parasite; and how the arrival of a non-native mudshrimp may eliminate any density-dependent restriction of the parasite's impact on the native mudshrimp population. (10/5)
My hypothesis that marine avian schistosome populations are sustainable only at sites where both the snail host and the primary avian host are present in great abundance, and may be spread to temporary, secondary sites by the bird hosts. In the case of San Francisco Bay's two swimmer's itch outbreaks at Crown Beach in Alameda, the main populations may have been at the Lake Merritt bird sanctuary, where both water birds and snail hosts are abundant, and exported by commuting birds to create a secondary population at the beach where people regularly wade in the water and are exposed to the cercaria. (10/5)

Anotado en 13 de octubre de 2019 a las 07:57 PM por ktnoon ktnoon | 0 comentarios | Deja un comentario