Arturo Ramirez-Valdez | University of California, San Diego (original) (raw)

Papers by Arturo Ramirez-Valdez

The US and Mexico share a common history in many areas, including language and culture. They face... more The US and Mexico share a common history in many areas, including language and culture. They face ecological changes due to the increased frequency and severity of droughts and rising energy demands; trends that entail economic costs for both nations and major implications for human well-being. We describe an ongoing effort by the Environment Working Group (EWG), created by The University of California’s UC-Mexico initiative in 2015, to promote binational research, teaching, and outreach collaborations on the implications of climate change for Mexico and California. We synthesize current knowledge about the most pressing issues related to climate change in the US-Mexico border region and provide examples of cross-border discoveries and research initiatives, highlighting the need to move forward in six broad rubrics. This and similar binational cooperation efforts can lead to improved living standards, generate a collaborative mindset among participating universities, and create an international network to address urgent sustainability challenges affecting both countries.

A large patch of anomalously warm water (nicknamed “the Blob”) appeared off the coast of Alaska i... more A large patch of anomalously warm water (nicknamed “the Blob”) appeared off the coast of Alaska in the winter of 2013–2014 and subsequently stretched south to Baja California. This northeastern Pacific warm-water anomaly persisted through the end of 2015. Scientists and the public alike noted widespread changes in the biological structure and composition of both open ocean and coastal ecosystems. Changes included geographical shifts of species such as tropical copepods, pelagic red crabs, and tuna; closures of commercially important fisheries; and mass strandings of marine mammals and seabirds. The
ecological responses to these physical changes have been sparsely quantified and are largely unknown. Here, we provide a bottom-up summary of some of the biological changes observed in and around the areas affected by the Blob.

Located in the central region of the west coast of Baja California Peninsula, the Cedros Archipel... more Located in the central region of the west coast of Baja California Peninsula, the Cedros Archipelago consists of five continental islands (Cedros Island, Natividad, San Benito Este, Medio, and Oeste), with Cedros being the largest island in the Mexican Pacific. This archipelago represents the biogeographic transition zone between the temperate and subtropical region and hence, the end of the geographic distribution of a large number of species. Based on field surveys, literature, and scientific collection records, an exhaustive species list of fishes associated with the archipelago and their biogeographic relationships is presented. The checklist includes 269 species belonging to 191 genera, 97 families, 31 orders, and 4 classes. Of the total species, 105 species were recorded in the field, 57 were the result of the literature review, and 218 species of the records were obtained from collections. A total of 14 biogeographic affinities are presented, where 51% of the species have warm-temperate or cold-temperate affinity and 37% have tropical-subtropical affinity. This work highlights the fish diversity present in a transition zone within the temperate and subtropical marine areas of the Northeastern Pacific. More importantly, it reveals a biogeographic region where a great number of species converge, and may be related with the evolutionary history of different taxa and the geological history
of the region.

The Cortez Province (CP) is located in the transitional warm-temperate/subtropical region that al... more The Cortez Province (CP) is located in the transitional warm-temperate/subtropical region that allows the ichthyological component inhabiting it to be a mixture of elements of different biogeographic affinities. Since the first systematic analysis of the fish fauna of the Gulf of California in the 1960’s a major portion of the endemic species was recognized. Subsequently, a total of 31 new endemic species have been described in the CP. This study constitutes an amendment of the fish component of the CP, including the most relevant ecological attributes of the species, along with an updated taxonomic list. A comprehensive literature review was made, considering current biological knowledge, and taxonomic status of the endemic species from the CP. Those fish species with restricted distribution ranges, falling within the limits of this province, were considered endemic. Additionally, and to recognize the dominant ecological attributes of the CP endemic species, the preferential habitat, bathymetric distribution, reproduction strategy, and the maximum total length (TL) were recorded. Seventy-nine endemic species were recognized and grouped in 13 orders, 29 families, and 59 genera. Gobiidae (12), Chaenopsidae (8), and Labrisomidae (7) are the families with the highest species richness, and Sebastes (6 species), the most diverse genus. Forty-five percent of the species are associated with coral and rocky reefs, with 35% distributed within the first 10 m depth layer. The dominant reproduction types are oviparous with benthic eggs and pelagic larval phase (48.7%), and oviparous with pelagic eggs (25.6%). More than half of the species (52%) are shorter than 10 cm (total length). The list of endemic species presented in this study is not conclusive, still undescribed species have not been included, detected differences (morphologic and/or genetic) in several species with disjunct populations may increase the diversity of this province.
Keywords: Gulf of California, endemic species, biogeography, Gobiidae

Dictyopteris prolifera, a marine algae (Phaeophyceae) native to Asian waters (Japan), has been co... more Dictyopteris prolifera, a marine algae (Phaeophyceae) native to Asian waters (Japan), has been collected recently on the western coast of the Baja California Peninsula, Mexico. Its finding represents the first record of this non-indigenous species on the Mexican Pacific coast, which also means a new record for American waters. Dictyopteris prolifera was found in June and September 2010, growing attached to rocks in the intertidal zone at Punta Morro Redondo, CedrosIsland in Baja California, Mexico. Direct observations in the field about its abundance and size showed that D. prolifera has established as a permanent species. The mean length of specimens of this population is 25 cm. Results of a monitoring programme show an increasing record of non-indigenous species on the coast of Baja California, mainly derived from ship traffic.

The composition and structure of the rocky intertidal fish community at various spatial and tempo... more The composition and structure of the rocky intertidal fish community at various spatial and temporal scales along the geographic gradient of the Californian and Cortezian provinces were studied. The main factors interacting in the ecological structure and dynamic of these fish assemblages were assessed monthly on Punta Morro (PM) beach, Ensenada, B.C., and seasonally form through 14 sites of the west coast in the Baja California peninsula (BCP). The fish monitoring during 14 months in PM showed that the taxonomic composition of this assemblage was persistent but variable in its abundance. The spatial-temporal composition of the fish community was represented by six resident species, two temporal species and five visitors, where 80% of the density of individuals was provided by resident species. The values of the ecological indexes of species richness and diversity (H´) show seasonal differences in the fish community, with maximum values in summer and minimum in winter. The most dominant species, Clinocottus analis, contributed with approximately 44% and 50% of the total abundance and biomass, respectively. Significant differences among the assemblages of each studied tidepool were observed. The area and substrate type in the rocky tidepool were the factors that better explained these differences. Species distribution along the vertical gradient of the intertidal zone was azonal. The fish community was resilient after successive defaunations and the recovery was independent of the time length among sampling events. The rocky intertidal fish assemblage on the 14 sites through the BCP was composed by 42 species, 33 genera and 19 families. A discontinuous pattern in the ecological attributes of the fish community was recognized along the geographic gradient, which was mainly influenced by those assemblages located within the Sebastian Vizcaino and Todos Santos bays. The area comprised between Punta Abreojos and San Juanico, B.C.S., represent a transition zone between the warm temperate and subtropical faunas. Five species increased their northernmost distribution ranges, and other three toward the south of the BCP. The latitudinal gradient showed a significant correlation with the fish species diversity.

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Guadalupe Island, off Baja California, México, is an important fishing area which also harbors hi... more Guadalupe Island, off Baja California, México, is an important fishing area which also harbors high marine biodiversity. Based on field data, literature reviews, and scientific collection records, we present a comprehensive checklist of the local fish fauna, which is comprised of 328 species from 219 genera, 105 families, 30 orders, and 3 classes. Of these, 156 species represent new records. Almost half of the species (154) are from tropical waters and the remainders are typical of warm and cold temperate regions. The island is the type locality of 18 fishes, represents the range limit of 48 taxa, and has 8 endemics. A biogeographic analysis comparing Guadalupe and the Baja California Peninsula indicates that the composition of reef fishes of the island is very similar to that found at 28˚N, and suggests that Cedros, San Benito islands, and Punta Eugenia, might be the key sources of tropical immigrants to Guadalupe.

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The composition, density and biogeographic affinities of the rocky intertidal fishes of the weste... more The composition, density and biogeographic affinities of the rocky intertidal fishes of the western coast of the Baja California peninsula, Mexico, were studied from June 2006 to January 2009. A total of 5,489 specimens belonging to 48 species, 39 genera and 20 families were registered. Clinocottus analis was the dominant species on the northern and central coast (north to Punta Abreojos), and Entomacrodus chiostictus was dominant farther south. Based on distribution and density of permanent species, the area between Punta San Juanico and Bahia Magdalena represents the distributional boundary for northern (warm-temperate) and tropical fish elements. Most of species (85%) showed zoogeographical affinities with the San Diegan province, followed by species related to the Mexican (58%) and Cortez (56%) provinces. The known northernmost geographical ranges are extended for Sargocentron suborbitalis, Labrisomus multiporosus and Bathygobius ramosus; while the southernmost ranges extended for Clinocottus analis, Oligocottus rubellio and Amphistichus koelzi

The known geographic distribution of two reef fish species of Indo-Pacific affinity is increased:... more The known geographic distribution of two reef fish species of Indo-Pacific affinity is increased: Acanthurus nigricans and Cantherhines dumerilii. These species are reported for the first time from the Acapulco coast, Me´xico. Collection data, and morphometric and meristic characteristics of the studied specimens are presented.

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