The California Coastal Prairie has the highest biodiversity of North America's grasslands Stromberg et al. 2002, but also has the highest proportion of urbanization Loveland and Hutcheson 1995. The most urbanized part of the California Coastal Prairie is its southernmost area, located in Los Angeles County. This southernmost region, known as the Los Angeles Coastal Prairie, was historically sequined with vernal pools, and has a unique biodiverse composition Mattoni and Longcore 1997. More than 99.5% of the estimated 95 km² (23,475 acres), and almost all vernal pool complexes, have been lost to urbanization Mattoni et al. 2000. The remaining estimated thirty hectares (approximately 74 acres) has undergone considerable degradation. Notwithstanding these urbanization pressures, the remaining fragments of the Los Angeles Coastal Prairie harbor a rich and understudied macro-invertebrate biodiversity.

The Madrona Marsh Preserve FoMM 2015 (MMP, or "the Preserve") is a public nature preserve located in the City of Torrance, California; see Figs 1, 2. At approximately 18 hectares (44 acres), it safeguards the largest remnant of Los Angeles Coastal Prairie, as well as its last functional vernal pool complex.

Figure 1.  

Madrona Marsh Preserve

Figure 2.  

Madrona Marsh Preserve - Willow forest

MMP is located in the South Bay area of Los Angeles County (33.827° North; 118.341° West) at approximately 24 meters (80 feet) elevation above sea level (see maps in Fig. 3​). The Preserve is surrounded by urban areas, including California's second largest shopping mall on its west side. It is bounded by Madrona Avenue on the west, Sepulveda Boulevard on the south, Maple Avenue on the east, and Plaza del Amo on the north. MMP is 4.2 kilometers (2.63 miles) inland from the Pacific Ocean coast and 4.8 km (3 miles) north of natural open space on the Palos Verdes Peninsula, particularly the Linden H. Chandler Preserve, managed by the Palos Verdes Peninsula Land Conservancy PVPLC 2015. It is 5.3 km (3.3 miles) west-northwest of the Bixby Marshland LACSD 2015, 6.8 km (4.2 miles) southwest of the Gardena Wil­lows Wetland Preserve Friends of Gardena Willows 2015, and 13.8 km (8.6 miles) southeast of the LAX Dunes LAWA 2015. MMP is 17.1 km (10.6 miles) southeast of the Ballona Wetlands Friends of Ballona Wetlands 2015, which includes estuarine, brackish, and freshwater marshlands, and is located scarcely outside the northern historical boundary of the Los Angeles Coastal Prairie. The Santa Monica Mountains National Recreation Area SMMNRA 2014 lies 30 km (19 miles) to the northwest, and the Channel Islands National Park NPS 2015, with Santa Barbara Island, 72 km (45 miles) to the southwest.

Figure 3.  

Location of Madrona Marsh Preserve (MMP) in Torrance, California.

Insets depict MMP's location with respect to the United States of America and southern Los Angeles County respectively.

MMP has a Mediterranean climate with mild, dry summers and cool, wet winters. The annual average precipitation is 37.6 centimeters (14.8 inches), which almost all falls between mid October and late March. August is usually the warmest month of the year, with an average maximum temperature of 25.9 degrees Celsius (78.7 degrees Fahrenheit). December is usually the coldest month of the year with an average minimum temperature of 7.8 °C (46.0 °F). Temperature variations between night and day vary from an average of 9 °C (17 °F) in summer to 11 °C (20 °F) in winter U.S. Climate Data 2015.

MMP is a nature oasis in an urban setting; see map in Fig. 4. Lo­cated in the City of Torrance, being a jewel along the Pacific Flyway Pacific_Flyway 2015, MMP is well known for its avifauna Lyle 1999, Wikipedia 2016. Aside from its well-documented bird richness, its vertebrate fauna, as well as its vascular flora, have also been studied to some extent in the past City of Torrance 1976. Although its aquatic biodiversity had been stud­ied, predominantly down to ge­nus level Angelos 2003, its ter­res­trial macro-invertebrate fauna was virtually unknown, aside from but­ter­flies and odonata observations. MMP butterfly sighting records have been primarily obtained by David Moody, Tracy Drake, Jess Morton, Martin Byhower, Kevin Larson, and Mitch Heindel. MMP odonata observations began in 2004, initiated by the second author. Summaries of the butterfly and odonata tallies have been published periodically by the second author in the Marsh Mailing, the periodic newsletter of the Friends of Madrona Marsh FoMM 2015.

Figure 4.  

Map of Madrona Marsh Preserve.

Each red X-mark indicates the location of one of the ten pitfall traps. Each purple C-mark indicates the location of one of the eight sets of three coverboards.

Vegetation is shown in shades of green and yellow, vernal pools in pink, water inundation levels in shades of blue, the remaining upland areas in shades of light brown, and man-made structures in darker brown. Prominent trees and shrubs are indicated by black letters in pink-rimmed white circles. The Nature Center, surrounded by native plant gardens, is located north of Plaza del Amo, and the sump, a neighborhood runoff water collection reservoir, is located in the southeast corner of the preserve.

Map created by Jerry Cole, 2011.

Between November 16, 2009 and August 31st, 2011 the first author conducted a minimally-invasive bio­diversity inventory of the macro-invertebrates of the Preserve, often accompanied by the second author during field work. This study was part of a biological inventory that also included vertebrate animals and vascular plants. Goals of the bio­inventory included researching his­tor­i­cal data, providing a baseline inventory of the current MMP taxa to be able to compare future in­ven­tory date to, creating factual knowl­edge for education and outreach, as well as providing habitat restoration and enhancement recommendations for the Preserve.

The MMP macro-invertebrate bioinventory is unique in several aspects. It is the first macro-invertebrate bioinventory of its kind and scope, uniquely based on photographic vouchers, rather than the traditional captured specimen vouchers. It was performed with minimal manpower, and its scope is broad, aiming to include all taxa. This novel approach is made possible due to the advent of high-quality digital photography, which allows for taking, processing, organizing, and archiving large amounts of detailed photos, needed for such a project. The Internet is another technology that enables small teams to complete macro-invertebrates bioinventory projects in a limited time. BugGuide in specific is an extensive on-line resource with an unprecedented collection of more than 820,000 arthropod photos, taxonomically classified and organized by more than 280 editors and experts BugGuide 2014.

Related studies by others - an overview

Biodiversity, including urban biodiversity, is critical to human sustainability Kim and Byrne 2006. Most biodiversity studies include vertebrate animals or vascular plants, or both. Few inventories include invertebrate animals, non-vascular plants, or organisms of other kingdoms in their scope Gullison et al. 2015Pocock et al. 2015Schuldt and Assmann 2010. Macro-invertebrates are ubiquitous and account for the largest percentage of all metazoan biodiversity. They also account for the largest percentage of endemic taxa and taxa of concern (threatened, endangered, or otherwise imperiled), although most such invertebrates have not yet been officially recognized as being imperiled. The International Union for the Conservation of Nature’s Red List IUCN Red List 2016 estimates the global total at about 1.3 million invertebrate species and the percentage at risk of extinction at about thirty percent (30%) of species evaluated Center for Biological Diversity 2015. Macro-invertebrates are primary candidates for monitoring environmental impacts, as they respond quickly to environmental changes due to their short life cycle. Moreover, they are a crucial building block of the food-chain, and our global biosphere in general. The famous American myrmecologist Edward O. Wilson said: "If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos." Jarski 2007.

Surprisingly few macro-invertebrate or all-taxa inventories have taken place in general Kim and Byrne 2006, including in well-populated Southern California. Some prominent bio-inventories performed in Southern California that focused on, or included, macro-invertebrates, are listed in Suppl. material 1. The table, which is ordered by number of taxa found, includes studies whose results were published by the end of the MMP bioinventory in 2011. More recent studies show more up-to-date results. The bio-inventories listed in Suppl. material 1 are also briefly discussed below; ordered in decreasing proximity, or relevance, to MMP.

Mark Angelos performed a high-quality study of MMP's vernal pool arthropods, gastropods, vertebrates, and plants, between 1993 and 2003. At that time he was Research Associate in Invertebrate Zoology at the Los Angeles County of Natural History. He predominantly used nets and recorded 76 animal taxa, of which 67 arthropods, five mollusks, and four vertebrates; most of which he identified to genus Angelos 2003. Between 1997 and 2003 he performed a study of MMP's ostracods, small aquatic crustaceans, of which he found seven species in MMP’s vernal pools Angelos 2005.

W. Dwight Pierce, together with Dorothy Pool and others, performed field studies in the El Segundo Dunes from 1938 to 1939 and published highlights of their findings in a series of articles published between 1938 and 1947 Pierce et al. 1947. Their field notes, which include 187 arthropods and 38 (mostly marine) mollusks, were never published Pierce and Pool 1939.

Rudi Mattoni and his team performed a study of the flora and fauna of the 746 hectares (302 acre) El Segundo dune remnant at the west side of Los Angeles International Airport (LAX) from June 1987 to June 1988 Mattoni 1990. The used a combination of pitfall and yellow-pan traps, aerial net sweeping, beat-sheets, and Malaise trapping, as well as a mercury vapor and a ultra-violet (UV) light for night data collection. Their faunal study included invertebrates and yielded 728 arthropod and three mollusk taxa. Sand-obligate invertebrates restricted to Southern California coastal dunes were listed in his 1993 publication on the Los Angeles Coastal Prairie Mattoni 1993. A follow-up study was performed from 1992 to 1993 to sample arthropods on, and adjacent to, the El Segundo Dunes Mattoni et al. 2000. They collected 169 species in yellow pan traps and 189 species in pitfall traps. Nine (9) arthropod species (one spider, four moths, one cricket, and three weevils) were listed as endemic to the El Segundo dunes Mattoni et al. 2000.

Travis Longcore, who participated in the arthropod study mentioned above Mattoni et al. 2000, performed a five year terrestrial arthropod study of thirteen (13) locations on the Palos Verdes Peninsula, in south­western Los Angeles County, plus two locations in Crystal Cove State Park in coastal Orange County Longcore 1999. He found 204 arthropod taxa in his pitfall traps.

The Ballona Wetlands, located north of the northern boundary of the Los Angeles Prairie, consisted of approximately two thousand acres of coastal wetland habitat. Most of these wetlands have been lost to urbanization, including nine hundred acres for the construction of a small craft harbor and adjoining community in the 1960's, now known as Marina del Rey. The remaining six hundred acres consist of estuarine, brackish, and freshwater marshes, seasonal wetlands and other riparian habitats, as well as uplands. From 1980 to 1981, a one year biological study was performed on the Ballona Wetlands, which included the recording of 475 insects and mollusks Schreiber 1981. They used a combination of aerial, sweep, and aquatic nets, baited pitfall traps, Malaise trap, yellow pan traps, UV light traps, soil sifting, and Berlese funnel sifting. The specimens have been absorbed into the main entomology collection at the Los Angeles County Museum of Natural History.

Emile Fiesler conducted a macroinvertebrate bioinventory of the Oxford Basin in 2010. The Oxford Basin, located in Marina del Rey, is one of the last remaining areas with intertidal mud flat habitat in Los Angeles County. He recorded 85 terrestrial and marine taxa (two mollusks, eight spiders, 67 insects, and eight other arthropods), using macro-photography, during three half days of field work spread over four months Fiesler 2010.

Louis LaPierre and Pamela Wright surveyed the arthropod fauna of the Kenneth Hahn State Recreation Area during June and July of 2000 LaPierre and Wright 2000. The Kenneth Hahn State Recreation Area is located in the Baldwin Hills, which are situated approximately halfway between the Ballona Wetlands near the Pacific Ocean and downtown Los Angeles. They classified the habitat as "degraded Coastal Sage Scrub, dominated by California Sagebrush and Coyote Brush." The methods they employed were: pitfall traps, Malaise traps, yellow pan traps, beating sheets, aerial nets, black-lights and a mercury vapor lamp. They found 114 arthropod taxa (fourteen spiders, two isopods, 70 Lepidoptera (33 butterflies and 37 moths), 15 Coleoptera, 7 Hymenoptera, and six other insects) plus more than 99 undetermined morphospecies.

Emile Fiesler conducted a study of the non-marine macro-invertebrates of the Santa Monica Mountains National Recreation Area (SMMNRA) Fiesler 2009. This pilot study consisted in estimating the num­ber of non-marine macro-invertebrate families present in SMMNRA, compiling a complete list of butterflies that could potentially be found in the SMMNRA, compiling a list of invertebrates of concern (rare, endemic, threatened, or endangered), and creating a preliminary list of 160 non-marine macro-invertebrates representing 160 distinct families. The family list is comprised of twenty arachnids, seven myriapods, three crustaceans, two mollusks, one nematomorph, and the rest hexapods. He extracted this list from 410 (pre-project) plus 530 (new) specimens that are vouchered by approximately 6,200 photos. Based on this pilot study, the first author created an on-line field guide with the title: "Field Guide to the Insects and other Invertebrates of the Santa Monica Mountains" Fiesler 2016.

Peter Bryant has set-up an extensive internet website on the biodiversity of "Orange County and nearby places" Bryant 2014. Orange County is situated directly south and southeast of Los Angeles County. The hierarchically organized website's scope includes all taxa: animals, plants, fungi, and more. Each taxon is usually represented by its common name, its scientific name, and one or more photos. Each photo has a caption, which typically contains information on the photographer and the location and date where the photo was taken. Selected taxa are accompanied by information on biology, ecology, taxonomy, or other topics.

Nancy Hamlett is in charge of an all-taxa biota study of the 210 ha (85 acre) Robert J. Bernard Biological Field Station of the Claremont Colleges. The Bernard Field Station is located in the city of Claremont, approximately 58 km (36 miles) east of downtown Los Angeles. The ongoing study covered 352 invertebrate taxa, as well as vertebrates, plants, and lichens Hamlett 2014.

Studies on plants, vertebrate animals, and insects of the 2,469 ha (6,100 acre) Philip L. Boyd Deep Canyon Desert Natural Reserve have been coordinated by the University of California, Riverside. The Reserve is located five miles south of the City of Palm Desert in Riverside County; in the Colorado Subdivision of the Sonoran Desert. A succession of researchers, students, and visiting scientists have surveyed insects at the Reserve over the past 34 years Frommer 1988. The insect survey, primarily utilizing Malaise traps, has yielded about 5,000 insect taxa, 2,600 of which have been classified. The specimens are curated at the University of California, Riverside entomology collection.

An all-taxa bioinventory was conducted as part of the San Diego Bay Integrated Natural Resources Management Plan TD 2011. A key finding was that climate change and invasive species are now principal drivers of change, whereas habitat loss due to development was the main driver in the past for the San Diego Bay. More than 650 taxa of marine, estuarine, and salt marsh invertebrates were recorded at species-, or genus-level, as part of the bioinventory that was primarily based on trawling.

Gordon Pratt conducted a survey of the terrestrial arthropods of Edwards Air Force Base between January 1996 and October 1998 Pratt 2000. Edwards Air Force Base is located in the Mojave Desert, in northeastern Los Angeles County, approximately 36 km (22 miles) northeast of Lancaster. He encountered 1,536 species from 32 sites, using sight, nets, and pitfall traps.

The Southern California Association of Marine Invertebrate Taxonomists (SCAMIT) has compiled a list of benthic macro- and mega-invertebrates. The data is compiled from various infaunal and epifaunal monitoring and research programs conducted in the Southern California Bight, mostly based on trawling. The Southern California Bight area covered by the list extends from Point Conception in Santa Barbara County, California to Bahía Todos Santos, Baja California Sur, Mexico, in intertidal to 1000 meter depths. This geographical area includes the off-shore areas of Los Angeles, Orange, San Diego, and Ventura Counties, plus the southern section of Santa Barbara County and the northwestern-most section of Baja California Norte. The ninth edition lists 3,177 taxa Cadien et al. 2014.

The following sections detail the methodologies used for the terrestrial and aquatic invertebrates surveys. The surveys performed for this project are unique as they were conducted with minimal invasiveness. A minimally invasive study aims at studying organisms with minimum disturbance and without collecting them; relying primarily on high-resolution digital photography. To maximize taxonomic identification success, close-up photos are taken from various angles, where possible. Nevertheless, not having a specimen in hand tends to increase the complexity of taxonomic identification, as certain characteristic details, some of which could be internal, might not be visible.

Terrestrial invertebrates data collection methodology

Aquatic invertebrates data collection methodology

Arthropod taxonomy

Before presenting the overall results, the outcome of a few selected data collection methodologies are presented, as they tend to contain method-specific data of interest.

Pitfall trap results

The pitfall trap results yielded several species not recorded by the other methodologies. The most striking find was Ceuthophilus hesperus clunicornis Hubbell, 1936, (San Diego camel cricket); see Fig. 5. Given the fact that they are flightless, and hence limited in their dispersal, it is very likely that camel crickets have been present at the site for a long time. Camel crickets are among the least studied orthopterans (order: Orthoptera, or “straight-winged” insects), which include all grass­hoppers, katydids, crickets, and allies.

Figure 5.  

Ceuthophilus hesperus clunicornis Hubbell, 1936 (San Diego camel cricket)

Other unique pitfall trap discoveries are three small native beetles:

• A somewhat elongated beige-brown beetle with two unusually long claws on each foreleg. This is Lepidocnemeplatia sericea (Horn, 1870), a darkling beetle, see Fig. 6, (family: Tene­brionidae); which is fairly widespread in the Southwestern United States, but not often encountered.
• A new family for the Preserve was the discovery of Xerosaprinus sp., a clown beetle, see Fig. 7, in the family Histeridae.
• The third beetle was a snout beetle, also known as a weevil. It was in one of the two traps near the waterline. It is Stenopelmus rufinasus Gyllenhal, 1835, also known as Azolla weevil or water fern weevil; see Fig. 8​. It's life cycle is dependent on the presence of the native Azolla filiculoides Lam. (Pacific mosquito fern) in the family Azollaceae.

Figure 6.  

Lepidocnemeplatia sericea (Horn, 1870) (a darkling beetle)

Figure 7.  

Xerosaprinus sp. (a clown beetle)

Figure 8.  

Stenopelmus rufinasus Gyllenhal, 1835 (Azolla weevil)

The pitfall trap closest to the waterline yielded, besides two aquatic ground beetles, many hundreds of springtails (class: Collembola); see Figs 9, 10. The data collected during the pitfall trap sessions have been added to the taxon list in Suppl. material 2.

Figure 9.  

Collembola (Springtails) and Linepithema humile (Mayr, 1868) (Argentine Ants)

Figure 10.  

Collembola (Springtails) and Linepithema humile (Mayr, 1868) (Argentine Ants) - detail

Nighttime observations

Aquatic invertebrates

Environmental conditions

During the project period, more than 12,500 digital photos were taken, processed, identified, and archived. Besides those, more than 9,500 digital photos had been taken and archived during the period from 2003 until the start of the project. A small fraction of this older data have been processed and identified and these taxa have been included in this report. Combining all the available data, a total of 689 invertebrate organisms were recorded, covering 8 phyla, 13 classes, 39 orders, and 222 families. A summary of the statistics for the highest, and some of the most salient, taxa are given in Table 3. The orders with the largest number of recorded taxa are, in decreasing order: Diptera (155 taxa), Coleoptera (106 taxa), Hymenoptera (101 taxa), Lepidoptera (84 taxa), Hemiptera (82 taxa), and Araneae (48 taxa).

All the 689 taxa are listed in Suppl. material 2, sorted alphabetically in a hierarchical way, starting at phylum level, down to subspecific level. The list contains all invertebrate taxa recorded, including small arthropods like aphids, thrips, and mites, as well as all recorded microscopic aquatic taxa. Some taxa above species level appear identical in Suppl. material 2. These taxa are based on sufficiently different morphotypes.

Of particular interest is the presence of native flightless species, that have likely persisted throughout the human-influenced history of the land that is now Madrona Marsh Preserve, including:

• Typhoctes peculiaris peculiaris (Cresson, 1875), a bradynobaenid wasp, see Fig. 11; whose females are flightless,

• Pseudomethoca anthracina (Fox, 1892), a velvet ant, see Fig. 12; whose females are also flightless,

• Eremobates sp., a large solifugid, see Figs 13, 14, and

• Ceuthophilus hesperus clunicornis Hubbell, 1936, San Diego Camel Cricket, see Fig. 5.

Figure 11.  

Typhoctes peculiaris peculiaris (Cresson, 1875) (a bradynobaenid wasp) female

Figure 12.  

Pseudomethoca anthracina (Fox, 1892) (a velvet ant) male

Figure 13.  

Eremobates sp. (a solifugid)

Figure 14.  

Eremobates sp. (a solifugid)

Some taxa were notable for their absence, including Diplopoda (millipedes), Opiliones (harvestmen), Scorpiones (scorpions), Pseudoscorpiones (pseudoscorpions), cockroaches, Mantodea (mantids), Phasmida (stick insects), Nematomorpha (hairworms), and Diplura. Diplopoda (millipedes) have been observed by Walt Wright (MMP manager preceding Tracy Drake) in the past, but have possibly been extirpated. Similarly, only one kind of Chilopoda (centipede) was found, and only in small numbers. Native Corydiidae (sand roaches) are not expected at MMP due to lack of soft sand habitat, and adventive cockroaches have been recorded in urban areas not far from the Preserve, but are closely associated with human activity and not expected to be permanent resident on the Preserve. Native mantids are relatively uncommon in Los Angeles County and not expected at MMP due to its isolation within urbanization. Adventive mantids are introduced in urban settings as pest control, and it is no surprise not to find them on the Preserve either. Most of the remaining taxa that were not found are associated with fairly undisturbed habitats or other habitats that are not present at the Preserve.

Some notorious and ubiquitous Los Angeles County adventives, like Ceratitis capitata (Wiedemann, 1824) (Mediterranean Fruit Fly), Homalodisca vitripennis (Germar, 1821) (Glassy-winged Sharpshooter), and Sophonia orientalis (Matsumura, 1912) (Oriental Leafhopper) were not recorded from MMP. An interesting adventive species that was recorded from the Preserve is the Outer Barklouse Ectopsocus strauchi Enderlein 1906, see Figs 15, 16, which is native to Europe and found in eastern parts of the United States. This finding constitutes the first west coast record for this species. Overall, relatively few adventive taxa were identified: six introduced for bio-control, two migrants that expanded their range, and 44 other adventive taxa, of which only a fraction might be labeled as destructive pest. All three categories of adventive taxa combined represent less than 8 % of MMP's invertebrate fauna.

Figure 15.  

Ectopsocus strauchi Enderlein, 1906 (a barklouse)

Figure 16.  

Ectopsocus strauchi Enderlein 1906 (a barklouse)

No doubt species will be found in the future that are not on the list. These will predominantly be new colonizers, visiting vagrants, and obscure spe­cies in under-sampled habitats, including in­fauna of the soil, microscopic aquatic fauna, and ectoparasites of vertebrates, which were outside the scope of this project. Also, as mentioned before, years with different weather patterns are likely to reveal species that were not encountered during the study period.

This study can nevertheless be considered quite successful, given the available time and other resources. The list of recorded taxa will change over time, as some species come and some go, especially winged ones. The current list constitutes a solid baseline to compare future data with, and can be used as data source for educational and outreach purposes.

Gratefully acknowledged are the Friends of Madrona Marsh and the City of Torrance for their financial support of part of this work.