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Range expansion or range shift? Population genetics and historic range data analyses of the predatory benthic sea slug Phidiana hiltoni (Mollusca, Gastropoda, Nudibranchia)
Full text linkPhidiana hiltoni is a conspicuous nudibranch sea slug native to the northeastern Pacific Ocean. Over the past thirty years the range of P. hiltoni has expanded about 200 km northward, but the mechanism that facilitated this expansion is poorly understood. In this study, we use mtDNA and microsatellite data to investigate the population structure of P. hiltoni in its historical range as well as in recently colonized localities. Microsatellite analyses reveal little to no genetic structure and thus high gene flow throughout the range of P. hiltoni. This is consistent with mtDNA analysis results, which revealed shared haplotypes between Southern, Central and Northern populations. However, AMOVA of mtDNA data did recover some genetic structure among geographic regions. This, along with same group memberships in the microsatellite data of individuals from sites like Cave Landing, suggest a certain degree of local recruitment and reduced vagility. Recently established populations in Northern California contain two unique mtDNA haplotypes that are not present elsewhere, but microsatellite data do not differentiate these from other populations. The mismatch between mtDNA and microsatellite data could be explained by the mating system of this aggressive, hermaphroditic species as well as the sporadic nature of the northward dispersal. Analyses of historical abundance data of P. hiltoni suggest a population decline in Southern California. Together, these results suggest a northward population shift, rather than a range expansion, possibly related to ongoing changes in nearshore oceanographic conditions in the region
Featured Artist - Living Betwixt and Between: The Liminal in Transnational, Transracial Adoption
Full text linkExperimental Elucidation of the Life Cycle of Rhinebothrium urobatidium (Cestoda: Rhinebothriidea) From the Round Stingray (Urobatis halleri: Myliobatiformes) To First And Second Intermediate Hosts
No full textAbstract - The life cycle of the cestode Rhinebothrium urobatidium, whose final host is the round stingray Urobatishalleri, includes a copepod as the first intermediate host and small benthic fishes as second intermediate hosts. Hexacanth embryos within nonoperculate, untanned eggs collected from U. hallerideveloped in the copepod Tigriopus californicusinto caudate procercoids with an apical organ/sucker and cercomer, and rarely, bothridia. The procercoids, which developed in the body cavity within a membrane, adhered to the copepod intestine, were infective to arrow gobies (Clevelandia ios) within 15 days of exposure at 21°C. When infected copepods were fed to arrow gobies, procercoids developed into nonlacunate plerocercoids each bearing individually retractable bothridia and an apical sucker. Within 10 days of exposure to the second intermediate host, the larvae had migrated up the bile/cystic duct into the gall bladder, where they developed bothridia similar to those of adult worms. Between 30 to 51 days post-infection in the goby, plerocercoids approached the size of larvae found in natural infections, and the scolex became morphologically similar to that of adult worms from round stingrays. Only presumptive filiform microtriches (filitriches) were present on procercoids while both filitrichs and spiniform microtriches (spinitrichs) were present on plerocercoids. Identification of plerocercoids from experimental infections as those of R. urobatidiumwas confirmed through morphology of the scolex and using cytochrome c oxidase I sequences. The experimental transmission of R. urobatidiumto first and second intermediate hosts provides improved understanding of the transmission and ontogeny of shark tapeworms. The biological characteristics of U. halleri,with its diverse parasite fauna, provide significant opportunities to examine the biology of an array of elasmobranch tapeworm taxa
Secondary Production of Kelp Bass Paralabrax clathratus in Relation to Coastal Eelgrass Zostera marina Habitat in a Southern California Marine Protected Area
No full textSeagrasses are an important refuge for fishes and provide ecosystem services worldwide. Along the Pacific Coast, however, quantitative assessments of the ecological role of seagrass habitats with limited anthropogenic impacts are lacking despite their value to resource management. To address these issues, the ecological function of the eelgrass Zostera marina Linnaeus in a protected area off Santa Catalina Island, California, USA was quantified using estimates of secondary production in the kelp bass Paralabrax clathratus (Girard 1854). Monthly assessments of eelgrass structural complexity, as well as the size and abundance of juvenile kelp bass were used to establish a baseline of fish biomass and recruitment associated with Zostera habitat. The greatest number of kelp bass was recorded in the summer and fall months and the fewest during the winter and spring. Secondary production in kelp bass (0.1 to 0.59 g m−2 mo−1) followed monthly changes in Zostera habitat structure throughout the 24-month study period. Seasonal changes in the structural complexity of coastal eelgrass beds may influence the flow of energy to adjacent reef environments through the transfer of fish biomass. These findings will help to define the role of Zostera habitat within the larger context of nearshore coastal ecosystems in the Southern California Bight
Embodying Refusal: Resistance, Pathologization, and Mental Health Exemption in the Israel Defense Forces
Full text linkThis paper examines the cultural elements of obtaining a mental health exemption from military service in the Israel Defense Forces (IDF). This paper also examines the social inequalities that Israeli militarism creates within Israeli society which can motivate Israelis to avoid or refuse to complete mandatory military service. Often, an Israeli’s ethno-class affiliation influences why they might avoid or refuse to serve and affects how they refuse or attempt to gain an exemption from the military. I argue the IDF individualizes refusal and exemption as an attempt to mitigate social, political, and ethical claims and critiques about the military and Israeli society. Then, using findings from my field research, this paper discusses the practice of gaining a mental health exemption as a way to refuse military service. An individual seeking mental health exemption is required to embody the military’s interpretation of the “proper” symptoms of a pathologized mental disorder. I argue the military’s attempts to depoliticize mental health exemption by individualizing and pathologizing mental disorders as well as mental health exemption. I consider how mental health exemption can be resistance to militarism and military service. This paper examines how a military pathologizes mental health issues, depoliticizes avoidance and critique of the military, and informs how individuals practice resistance to military service by using the military’s own bureaucratic practices
Behavior of Young-of-the-Year of Giant Sea Bass, Stereolepis gigas, off the sandy beaches of Southern California
Full text linkWe made extensive observations in the shallows off sandy beaches along the southern California coastline from 2013-2018 using SCUBA. The common diurnal behavior of young-of-the-year (YOY) of giant sea bass (Stereolepis gigas) were documented, in detail, and categorized the while they occupy their unique nursery areas. We identified and described the frequently observed behaviors referred to as 1) “kelping”, 2) “resting”, 3) “traveling”, and 4) “burying”. Finally, through direct observation, mysid shrimp were confirmed as the primary diet of young-of-the-year of the giant sea bass off southern California. This is the first study to provide a behavioral overview of the YOY of this internationally listed, endangered species, and it bridges important gaps in our understanding of their early life history
Finding a resting place: How environmental conditions influence the habitat selection of resting batoids
No full textMany batoid species will form aggregations while resting on the seafloor; however, the environmental variables that drive resting habitat selection behavior, and how it varies among species are not well understood. Bat rays (Myliobatis californica), shovelnose guitarfish (Pseudobatos productus), and round stingrays (Urobatis halleri) have been observed forming heterospecific aggregations. We investigated the effects of substrata type and seafloor water temperature as two likely variables that would influence resting habitat selection for these species. Spatial distribution patterns of individuals were determined via diver-based surveys over two survey seasons (Fall 2013 and Summer 2014) and related to detailed georeferenced habitat maps. While these batoids were found resting on both soft sediment types available, fine-sand was selected by all three species, whereas bat rays were the only one of the three species to select for vegetated-sand. The varying thermal sensitivities of the batoids likely influenced their responses to daily and seasonal temperatures within the study area. During Fall 2013, the three species were most abundant across a narrow temperature range (18.00 – 18.25°C); during Summer 2014, there were higher densities of bat rays in areas where daily maximum seafloor temperature reached 20°C. Each species demonstrated habitat selection decisions that were indicative of balancing tradeoffs between environmental variables. As K-selected, meso-level predators, aggregating in predictable ways can ultimately make batoids more susceptible to fishing and anthropogenic pressures. Therefore, knowledge of how batoids select their resting habitat and how environmental conditions shape distributions may provide managers with opportunities to implement better protection for resting species
Status of Endangered La Graciosa Thistle Cirsium scariosum var. loncholepis (Asteraceae) in Coastal Southern California
Full text linkLa Graciosa thistle Cirsium scariosum var. loncholepis (Asteraceae) is a biennial or short-lived perennial plant (usually 10 to 100 cm tall) that is endemic to southwestern San Luis Obispo County and western Santa Barbara County in coastal southern California, and little has been published regarding it. The taxon was listed as threatened under the California Endangered Species Act in 1990 and endangered under the U.S. Endangered Species Act in 2000. At Federal listing in 2000, La Graciosa thistle was known from 17 occurrences, 8 of which were likely extirpated. As of 2019, it is known from 21 occurrences of which five are extant, 15 are likely extirpated and 1 has unknown status. La Graciosa thistle exists as groups of individuals in wetland habitats in an arid and semi-arid landscape, and the five extant occurrences are associated with the Callender Dunes and Guadalupe Dunes in San Luis Obispo County. The plants flower once and then die, with a probable life span of 2 to 6 yr. Seed dispersal is by wind and also likely by water, and the taxon appears to have only a minimally persistent soil seed bank. The primary threat to La Graciosa thistle in 2019 is reduced water/lack of water, with groundwater decline as the likely major cause, along with hydrological alteration, drought and climate change. The groundwater decline appears to result primarily from extraction for urban, agricultural and industrial uses, and it is exacerbated by drought and climate change. In 2019, La Graciosa thistle meets the IUCN criteria for endangered