Geology topics
James L. Bodkin
Publications and source records attributed to James L. Bodkin.
Mortalities of kelp-forest fishes associated with large oceanic waves off central California, 1982-1983
Observations of three incidents of the mass mortality of nearshore fishes are reported; each corresponded to periods of high-amplitude, long-period swells during the 1982-1983 El Niño event along the coast of central California. Members of the nearshore kelp forest fish assemblage, primarily of the genus Sebastes , accounted for 96% of the observed mortalities and S. mystinus (blue rockfish) alone accounted for 72%.
A sublittoral population of Pleurophycus gardneri Setchell and Saunders 1900 (Phaeophyceae: Laminariaceae) in central California
Published distributional records for the stipitate kelp Pleurophycus gardneri Setchell and Saunders 1900 (Phaeophyceae: Laminariaceae) indicae a geographic range from Montague Island (59°58’N, 147°22W), Alaska to Fort Bragg (39°27’N, 123°47’W), California (Druehl 1969, 1970; Kjeldsen 1972). P. gardneri is found primarily in rocky intertidal and shallow subtidal locations (Scagel 1967; Nicholson 1976). In California, populations of P. gardneri have been reported only from the lower rocky intertidal near Fort Bragg (Kjeldsen 1972). On 7 and 8 July 1982 and 23 March 1984 we censused stipitate kelps during SCUBS dives at a site 2.3 km south southeast of Pt. Sierra Nevada (35°41’ N, 121°18’W). we counted kelps in 1 x 5-m plots along a 50-m tape laid across the bottom in an arbitrarily predetermined direction from the skiff anchor. We also measured water depth at 1-m intervals along the tape, using a SCUBA depth gauge. On 20 August 1982, we used the same tehniques to sample kelp densities at a site 2.4 km east southeast of Pt. Piedras Blancas (35°39’N, 121°15’W). The most abundant kelps at the Pt. Sierra Nevada ste were Pterygophora californica Ruprect 1852 (Phaeophyceae: Alariaceae) and a species we tentatively identified as P. gardneri (Table 1). Based on specimens we collected on 8 July 1982, our field identification was subsequently confirmed by I. A. Abbot. Voucher specimens were placed in the Gilbert M. Smith Herbarium at Hopkins Marine Station, Stanford University, Pacific Grove, California.
Fish assemblages in Macrocystis and Nereocystis kelp forests off Central California
The abundance and species composition of conspicuous fishes were compared within two canopy forming kelp forests (giant kelp, Macrocystis pyrifera , and bull kelp, Nereocystis luetkeana ) in Central California. The primary investigative method was a subtidal belt transect, in which visual observation was used. The species composition of fish assemblages in the two canopy types was similar. Densities of fish were generally greater in Macrocystis than in Nereocystis forests. The major difference was the density of midwater species of the genus Sebastes . The blue rockfish, Sebastes mystinus , was the numerically dominant species in both canopy types. Estimates of the biomass of fish were about 2.4 times greater in Macrocystis beds than in Nereocystis beds.