Oclwrinus. C. Luteipennis, C. Opacus, C. Sulcicollis!. H Eterotlwps Aspera Tus, Omalitllll Algamm, Oiglmta Pacifica
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THE WASMAN JOURNAL OF BIOLOGY 35(2). 1977. pp. 169-195 YEAR-ROUND SURVEY OF STAPHYLI IDAE OF A SANDY BEACH I N SOUTHERN CALIFOR l A (COLEOPTERA) R. E. Orth. Ian Moore. And T . W . Fisher Abstract .-During a once a month year-round survey of the staphylinid population of a sandy beach at Refugio State Beach, Santa Barbara County. California. 35,3 10 specimens representing 31 species were collected. Twen ty-one of the species were considered indigenous to the beach , the remaining 10 species (II specimens) were considered accidental. Most species were seasonal in distribution. Predominantly winter pecies included Cafius lith oclwrinus. C. luteipennis, C. opacus, C. sulcicollis!. H eterotlwps aspera tus, Omalitllll algamm, Oiglmta pacifica. Thinu.w maritima, two uniden ti fied species of Atht!la and Aleoclwra arena ria . Summer ·pecic were Cafius canescens, C. seminitens, Thinopinus picws, Pontamalota opaca, and A leo chara sulcicollis. Hadrotes ('l'assus, Blediusfenyesi, Bryobiota bicolor. Tar phiota geniculata, anti T. pallidipes were encountered most of the year. Different species showed preference for either a pure andy beach or a rocky- andy beach. Spar ity of staphylinids on two occa ion was corre lated with large larval and ad ult fl y population · sugge ting natural biological control of beach flies by rove beetles most of the year. Introduction Mo t or the in ect found along the seashore of temperate Pacific North America are restricted to a very narrow habitat. The mo t interesting feature of thi eashore habitat i it linear nature. For mo t of it length it is only a few meter wide and transects almost the entire temperate zone of orth America. It extend from outhern Alaska to at lea t Punta Eugenio. Baja California. a distance of more than 3000 mile, . The unusual nature of this exten ive linear habitat offers exceptional opportunities for the study of insect biology (Moore and Legner. 1974). T he intertidal region of Pacific orrh America falb naturally into three distinct zones which occur repeatedly along the coa 1. These zones are: ( I) rocky headlands with ~ubmerged reefs: (2) andy beaches: and (3) salt flats of bays and es tuaries (Moore, 1956: Moore and L egner, 1976). These zones, in turn. may be conveniently divided into ubzones. defined by the reach of the tide. Eac h of th e zones and subzones supports a distinctive assemblage of insec ts which are se ldom found elsewhere (Moore, 1956). Among the LeJTestrial arthropods which may be found in the intertidal regions are mites. pseudo corpions. centipedes, earwigs. bugs, termites. 170 THE WASMANN JOURNAL OF BI OLOGY Table I. Total number of each species of Staphylinidae collected at Refugio State Beach: 35,3 10 specim ens were collected in all. Cajius canescens Maklin 239 Cajius seminirens Horn 315 Cajius lirlzoclwrinus LeConte 4247 Cajius /ureipenni.1· Horn 561 Cajius opacus LeConte 101 Cajius sulcimllis LeConte? 32 Hatfrotes cru.Hu.\' Mannerheim 312 Tlzinopinus picrus LeConte 4 Heterotlzops u.\'{Jertlf/1.1' Smetana 4 8/edius fenyesi Bcrnhauer & Schubert 45 10 Omalium algamm Casey 9 Diglouu pacifica Fenyes 17 Bryobiora bicolor Casey 84 Tlzinu .w maritima Casey 202 Pontamalnta opaca LeConte 86 Tarphiow geniwlaw Miiklin 22,712 Tarphiow pt1lliclipes Casey 38 Arhera sp. # I 275 Arhew sp.#2 14 Aleoclzara arenaria Casey 234 Aleochara sulciocollis Mannerheim 1303 Accidentals Aleochara bimaculata Gravenhorst Aleochara species Anoty/us rugosus Fabricius Anotylus species I Aploderus species 2 Lobrathium species Medon species Neobisnius species Philonthus longicomis Stephens Aleocharinae undetermined springtails, ants, parasitic wasps, flies, weevil s, and other beetles. Diptera and Coleoptera comprise the largest percentage of all intertidal insects in California, both in number of spec ies and individuals. Amo ng Coleoptera. Staphylinidae are the most abundant and the most conspicuous. Except for the describing and naming of spec ies, very few studies have been made regarding this fauna. Jones ( 1968) and Meyerdirk (1969) made preliminary ecological studies of Staphylinidae of the intertidal reefs of California, and Moore ( 1964) made such a stud y of a marine salt marsh. Large offshore kelp beds are a conspicuous feature of the Pacific Coast of North America. Masses of seaweed break loose from these kelp beds and wash ashore. This material (wrack) lying on the shore becomes the ultimate VOLUME 35. NUM BER 2 171 Fig. I. Overall view of collecting area at Refugio State Beach showing wrack on the beach. source of food for many seashore animals, probably including most of the seashore insects of the sandy beach. I f left stranded by a high tide, these masses of seaweed may remain on the beach undistu rbed for a few days to a week or more. L arge colonies of insects develop in this wrack (Moore , 1973). Moore and L egner ( 1974) pointed out that the only staphylinid larvae occurring in wrack in outhern California were occasional larvae of Cafius (Hadrotes larvae al o occur there) and that the developmental period of the e in ect probably takes place elsewhere. T he population buildup of adult in ects usually take place in j ust a few days. T hey peculated that development of the larvae probabl y occurs deep in the sand, and that adult insects are attracted to the wrack as a location where prey could be found. Craig ( 1970), L eech and Moore ( 1971). and James et al. ( 197 1) have dis cussed some aspec ts of the ecology of the insects inhabiting sand y beaches, but much more work remains to be done. T he fauna of this zone in southern California is endangered due to the removal of wrack from the beaches by the park and recreation departments of the state and counties (M oore and Legner, 1972). A consequent need to undertake further studies soon is ap parent. This study was initiated in an effort to determine the qualitative and quan titative composition of the adult staph ylinid fauna of southern California 172 THE WASMANN JOURNAL OF BIOLOGY Fig. 2. Rocky area at Refugio State Beach showing wrack trapped among the rocks. beach wrack. Monthly visits to Refugio State Beach, Santa Barbara County, California, were made for more than a year for the purpose of determining if the indigenous wrack species were cyclic. The frequency of encounter of these beetles should indicate whether the staphylinids were comprised of seasonal populations or were static throughout the year. A total of 35,310 staphylinid beetles (Table 1) was collected, mounted or preserved in alcohol , and studied in the course of this survey. Refugio State Beach Refugio State Beach (Figs. 1 and 2) , Santa Barbara County, California. li es at 34°28'N latitude. 120°04'W longitude approximately 250 miles (400 km) north of the Mexican border. The California coastline, in general, runs northwest and southeast. However, much of Santa Barbara County's coast line, including the region of Refugio State Beach, runs east-west. From near its junction with Ventura County to the south for more than 20 miles, the coastline runs due west to Point Conception; then, once again, resumes it s northwes terly direction. Point Conception is considered to be a barrier to the spread of some seashore insects (Moore and Legner, 1976). Refugio State Beach is near the northern limit of the Southern California Marine Province. VOLUM E 35. NUMBER 2 173 24° ........ 1/) ::;, ·v; 22" Q) (.) '-' 20° w cr ~ 1- 18° <l cr w a.. 16° =:E w 1- 14° z <l w 12° (.) 0 SEP. OCT. NOV. DEC. JAN. FEa MAR. APR MAY JUN JUL. AUG. Fig. 3. Ocean temperatures at Refugio State Beach during 1976 and 1977. Refugio State Beach is a composite of beach habitats. The main park beach is and. In contras t, the western collecting limit extend as a rocky promontory into the Pacific Ocean. The base of the headland in thi area arches in a southerly direction; near the high tide level is a linear mass of stones which range in size from small beach pebbles to very large boulders. When the tide is out, an essentially sandy beach is exposed below the rocky area. East of the main state beach, a sanely beach continues for nearly one mile where it is terminated by a rocky head land. ln the spring and ummer months, a wide sandy beach is present in front of the main ca mpground. Progressing west from the cam pground area, the beach gradually becomes rocky, but the rocky area is not extensive in su m mer. In the fall and winter months, much sand i removed from the beach by the action of the ocean so that the western rocky area i greatly enlarged . and the sand y beach i reduced in size. A s the easons progres and summer approache . and i:. agai n deposited along the beach until it again assumes its summer condition. Refugio State Beach is well suited for staph ylinids a there i generally an abundance of wrack along the sandy beach. The wrack remains undis turbed except for tidal changes that may either deposit additional material or remove that which has been previousl y deposited. T he rocky area with its boulders, at times, becomes festooned with kelp and other debris that washes ashore. Beneath and within the masses of decaying wrack there is a supply of invertebrates (insec ts, other anthropocl s, molluscs, worms, etc.) in various stage s of development. T hese ma y serve as food for the staph ylinids that occupy the wrack. 174 THEWASMANN JOURNAL OF BIOLOGY The ocean temperatures at Refugio State Beach (Fig. 3) ranged from a low in March and April of 13.3°C (56°F) to a high of 21.7°C (7 1°F) in October.