Environmental impact reduction through ecological planning at Bahia Magdalena, Mexico

For analyzing basic marine and coastal characteristics we selected the potential sites where shrimp culture could be developed in a large coastal zone, Bahia Magdalena, Baja California Sur, Mexico. Based on our analysis, 6 sites were preselected and field stages of work were then developed to assess the precise suitability of each site in order to develop the proposed aquaculture activities. In ranking the suitability we were able to recommend the most appropriate places to develop shrimp culture in this region. Also, knowing the exact biological, physico-chemical and social environment, we determined the best species to cultivate, the recommended total area and the methodology to be used to lessen the environmental impact and to obtain the maximum profitability Our methodology could be used not only to select appropriate sites for shrimp culture in other coastal lagoons, but it also could be applied to assess the suitability in a quick and accurate way, of any other production activity in coastal zones.     

Sustainable shrimp fishery management recommendations for a coastal lagoon in Baja California Sur,Mexico

The Baja California Peninsula is considered México's most productive in terms of commercial fisheries. Very few quantitative assessments of the economic importance of this region exist, especially considering artisanal fisheries and their relationships with ecological data. Datasets from government records on shrimp capture in Magdalena Bay, an arid coastal lagoon of Baja California Sur were collected, analysed and correlated with ecological data. Over the 10-year period analysed, fisheries from Magdalena Bay made up 27.5% of the shrimp capture of the state, contributing over US$15.5 million to the economy of the country. The impressive value of this resource warrants considerable attention in the design of land-use plans for the future of the region. Analysis of ecological and economical data on shrimp fishery activities in the Magdalena Bay region enables us to propose recommendations to enhance the sustainable development of the local inhabitants. A thorough assessment of the potential value of alternative economic activities should be conducted to determine their potential to provide similar productive use of the natural resources of the region as the shrimp fishery. Also, from a more specific management viewpoint, harvest rates of small shrimp in the channels should be reduced.     

Monitoring the production of Central California coastal rangelands using satellite remote sensing

There is a long history of livestock grazing on the California Central Coast, dating back over 150 years. In this study, methods were reviewed and results presented for analysis of NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor data to monitor year-to-year variation of forage production on Central Coast rangelands around Big Sur, California. Time series plots from 2000 to 2012 of vegetation greenness for ten rangeland sites showed similar inter-annual patterns in satellite yield index (SYI) values. Most sites reached their maximum greenness levels each year in early May. The year with the highest observed SYI level across most sites was 2005. In the northern portion of the region (north of Pfeiffer Big Sur State Park), 2007 was the year with the lowest observed SYI level, whereas in the southern allotments, 2007 was a year with a relatively high SYI level. These methods have the potential to monitor the differing seasonal growing cycles of rangeland production across the area of individual grazing allotments on the Central Coast. Such a cost-effective and timely approach is required for conservation monitoring in the Big Sur coastal ecosystems where rapid climate change may shift vegetation cover in favor of more extensive rangelands at the expense of forested lands.     

Genetics, Taxonomy, and Conservation of the Threatened California Gnatcatcher

Abstract: The California Gnatcatcher (   Polioptila californica ) has become a flagship species in the dispute over development of southern California's unique coastal sage scrub habitat, a fragile, geographically restricted ecosystem with high endemism. One aspect of the controversy concerns the status of the subspecies of this bird in southern California coastal sage scrub that is currently listed as threatened under the U.S. Endangered Species Act. To investigate the recent population history of this species and the genetic distinctiveness of subspecies and to inform conservation planning, we used direct sequencing of mitochondrial DNA (mtDNA) for 64 individuals from 13 samples taken throughout the species' range. We found that coastal sage scrub populations of California Gnatcatchers are not genetically distinct from populations in Baja California, which are dense and continuously distributed throughout the peninsula. Rather, mtDNA sequences from this species contain the signatures of population growth and support a hypothesis of recent expansion of populations from a southern Baja California refugium northward into the southern coastal regions of California. During this expansion, stochastic events led to a reduction in genetic variation in the newly occupied range. Thus, preservation of coastal sage scrub cannot be linked to maintaining the genetic diversity of northern gnatcatcher populations, despite previous recognition of subspecies. Our study suggests that not all currently recognized subspecies are equivalent to evolutionarily significant units and illustrates the danger of focusing conservation efforts for threatened habitats on a single species.     

Conservation or Commercial Management of Temperate Forests of Baja California Sur, Mexico

The current status of the oak and oak-pine forests in the Sierra de La Laguna range of the Baja California peninsula is examined from four perspectives: (1) the structural analysis of the woodlands; (2) the natural regeneration of hurricane windfall clearings and its effect on the oak-pine community; (3) the density, mortality, size, and commercial potential of the only pine species Pinus lagunae; and (4) the possible destruction of this endemic species by attack from moths. These factors were evaluated to make recommendations regarding the management and/or commercialization of the forest resources of this proposed Biosphere Reserve. Results show that the oak woodlands occurring at low elevations contain many tropical plants from the tropical dry forest that surrounds these woodlands, and that the tropical elements decrease at higher altitudes. In forest gaps, oaks were more abundant than pines. Gaps contained a lower diversity of perennial plants than mature oak-pine forest. P. lagunae has a high adult mortality, which can be attributed to the joint effect of fire and insect attack. Results indicate that the forest in this region does not have timber-yielding potential because of the small area it covers and because of the low tree diameters and volume, which are insufficient to carry out a continuous and income-producing extraction of the pine resource of Baja California Sur. Finally, options for management are discussed and future studies are proposed to determine the life cycle and extent of the moth populations.     

A critical geography approach to land and water use in the tourism economy in Los Cabos,Baja California Sur,Mexico

ABSTRACT

This paper offers a critical assessment of how tourism development in the municipality of Los Cabos, Baja California Sur affects land and water use. Los Cabos is a seaside tourism Mecca located at the southern tip of the Baja California peninsula, in Mexico’s northwest. There, subsidised profits and a process of dispossession in the tourism sector have to do mainly with land and water appropriation in the form of restrictions to beach access by the local population, urban segregation and, in an arid region, privileging water provision for the tourism industry over the needs of the population. In order to sustain these claims, we map water and land use for tourism in Cabo San Lucas. We also analyse the expansion of the Los Cabos type of tourism to the small town of La Ribera, in the East Cape-Cabo Pulmo area, where marinas and high scale housing for residential tourism sprout along the coast. We argue that the seemingly ever-growing presence of tourism in the region carries with it an urgent call for the reappraisal of current approaches to land and water use, if local resources are to deliver quality of life for the population, and not only economic profitability for (mostly) foreign capital. Analytically, we address these issues by unpacking David Harvey’s concept of accumulation by dispossession, which – we argue – is for our purposes a broader tent than the (mostly Latin American) theorisations on extractivism, as we explain later in the relevant section of the paper.     

Impact of cattle grazing on the occupancy of a cryptic, threatened rail

Impacts of livestock grazing in arid and semiarid environments are often concentrated in and around wetlands where animals congregate for water, cooler temperatures, and green forage. We assessed the impacts of winter-spring (November-May) cattle grazing on marsh vegetation cover and occupancy of a highly secretive marsh bird that relies on dense vegetation cover, the California Black Rail (Laterallus jamaicensis coturniculus), in the northern Sierra Nevada foothills of California, U.S.A. Using detection-nondetection data collected during repeated call playback surveys at grazed vs. ungrazed marshes and a "random changes in occupancy" parameterization of a multi-season occupancy model, we examined relationships between occupancy and habitat covariates, while accounting for imperfect detection. Marsh vegetation cover was significantly lower at grazed marshes than at ungrazed marshes during the grazing season in 2007 but not in 2008. Winter-spring grazing had little effect on Black Rail occupancy at irrigated marshes. However, at nonirrigated marshes fed by natural springs and streams, grazed sites had lower occupancy than ungrazed sites. Black Rail occupancy was positively associated with marsh area, irrigation as a water source, and summer vegetation cover, and negatively associated with marsh isolation. Residual dry matter (RDM), a commonly used metric of grazing intensity, was significantly associated with summer marsh vegetation cover at grazed sites but not spring cover. Direct monitoring of marsh vegetation cover, particularly at natural spring- or stream-fed marshes, is recommended to prevent negative impacts to rails from overgrazing.     

Recent introduction of an Asian estuarine copepod,Pseudodiaptomus marinus (Copepoda: Calanoida), into southern California embayments

Past studies made between 1938 and the mid-1970's of coastal embayments between northern Baja California and Oregon (USA) established the presence of only one species of the calanoid copepod genus Pseudodiaptomus, P. euryhalinus. This species is endemic to warm temperate latitudes of western North America. We now report the presence of breeding populations of the Asian calanoid copepod P. marinus in two Southern California embayments, Mission Bay and Agua Hedionda Lagoon. The Mission Bay population was monitored monthly from December 1986 to June 1987 and showed evidence of continuous breeding and growth. The regional, endemic species, P. euryhalinus, was not observed in either embayment. Mechanisms that might account for the apparent recent introductions of P. marinus into Southern California include dispersion by ocean circulations and transport by transoceanic ships. In the present case, the explanation is that the introduction is most likely a direct consequence of aquaculture projects. Remaining to be confirmed by systematic sampling is the apparent disappearance of P. euryhalinus from embayments dominated by P. marinus.     

Assessment of community-based initiatives in sustainable management of Indian dry deciduous forests

SUMMARY

This work is devoted to analyzing the pros and cons of the proposed San Ignacio Lagoon (SIL) salt production project in Baja California Sur, México. The analysis of the project was done taking into account the technical data of the main potential effects of the SIL project, and by comparing the SIL proposed actions with the data of Ojo de Liebre Lagoon, where an almost identical salt production project has been operating for more than 44 years. The analysis was done from the following perspectives: biodiversity, biosphere reserve management, and socioeconomic development. The resulting analysis of the pros and cons of the SIL salt production project addresses key aspects of sustainable development in Third World nations. The resulting analysis indicates that the SIL salt production project is compatible with the biodiversity conservation of the zone. The SIL salt production project seems to be one of the best options to attain the sustainable use of natural resources of the most arid and isolated zone of all México.     

Genetic mating system of the brown smoothhound shark (<Emphasis Type="Italic">Mustelus henlei</Emphasis>), including a literature review of multiple paternity in other elasmobranch species

Although an understanding of mating systems is thought to be an important component of long-term population management, these life history characteristics are poorly known in sharks. Here, we employ polymorphic microsatellite markers to test for the occurrence and prevalence of multiple paternity in a population of the brown smoothhound shark, Mustelus henlei. We analyzed litters from 14 females sampled from the Pacific coast of Baja California Sur. The minimum number of sires ranged from one to three with an average of 2.3 sires per litter. Regression analyses did not indicate a relationship between female body size and number of sires, or female body size and size of the litter. A review of the existing literature on genetic mating systems in sharks suggests that polyandry may be common and that reproductive behavior may have evolved from conflicting selection pressures between the sexes.     

Cattle Grazing Impacts on Annual Forbs and Vegetation Composition of Mesic Grasslands in California

Abstract:   Livestock grazing represents a major human alteration of natural disturbance regimes in grasslands throughout the world, and its impacts on plant communities have been highly debated. We investigated the impact of cattle grazing on the California coastal prairie plant community with a focus on native annual forbs, a number of which are of conservation concern. In spring 2000 and 2001, we surveyed the vegetation community composition, vegetation structure, and soil chemical parameters at 25 paired grazed and ungrazed sites over a 670-km range of the ecosystem. Native annual forb species richness and cover were higher in grazed sites, and this effect was concomitant with decreased vegetation height and litter depth. Soil properties explained less of the variation. Exotic annual grass and forb cover were higher in grazed sites. Native grass cover and species richness did not differ in grazed and ungrazed sites, but cover and species richness of native perennial forbs were higher in ungrazed sites. Our results suggest that cattle grazing may be a valuable management tool with which to conserve native annual forbs in the ecosystem we studied but that grazing differentially affects the various life-history guilds. Therefore, land managers must focus on creating a matrix of disturbance regimes to maintain the suite of species native to these mesic grasslands. The results of this and other studies highlight the importance of considering the adaptation of vegetation communities to disturbance in making recommendations for grazing management.     

The effects of intensive aquaculture on nutrient residence time and transport in a coastal embayment

Aquaculture in many countries around the world has become the biggest source of seafood for human consumption. While it alleviates the pressure on wild capture fisheries, the long-term impacts of large-scale, intensive aquaculture on natural coastal systems need to be better understood. In particular, aquaculture may alter habitat and exceed the carrying capacity of coastal marine ecosystems. In this paper, we develop a high-resolution numerical model for Sanggou Bay, one of the largest kelp and shellfish aquaculture sites in Northern China, to investigate the effects of aquaculture on nutrient transport and residence time in the bay. Drag from aquaculture is parameterized for surface infrastructure, kelp canopies, and bivalve cages. A model for dissolved inorganic nitrogen (DIN) includes transport, vertical turbulent mixing, sediment and bivalve sources, and a sink due to kelp uptake. Test cases show that, due to drag from the dense aquaculture and thus a reduction of horizontal transport, kelp production is limited because DIN from the Yellow Sea is consumed before reaching the interior of the kelp farms. Aquaculture drag also causes an increase in the nutrient residence time from an average of 5 to 10 days in the middle of Sanggou Bay, and from 25 to 40 days in the shallow inner bay. Low exchange rates and a lack of DIN uptake by kelp make these regions more susceptible to phytoplankton blooms due to high nutrient retention. The risk is further increased when DIN concentrations rise due to river inflows.     

Possible impact of sea-level rise on some habitat types at the Baltic coast of Denmark

According to estimates from the Danish Meteorological Institute global warming until 2080 may cause a relative sea-level rise in Danish waters of 33–46 cm. In the present paper the possible impact of a sea-level rise of this magnitude on coastal habitat types is discussed for three case studies, based on previous investigations of vegetation, topography and soil of localities at the Baltic coast of Denmark. The case studies include the following types of localities and habitats: (1) an off-shore barrier complex: sandy beach, sand dune, geolittoral, brackish, low-tidal meadow, reed bed; (2) a protected bay: geolittoral, brackish meadow, coastal grassland; (3) a dune area: mobile and fixed dune communities, and adjoining sea wall: coastal grassland. In the geolittoral meadow and coastal grassland habitats the sea-level rise is expected to cause a horizontal displacement of vegetation zones and a reduction in area, depending on accretion rate (sedimentation, peat formation), local topography and inland land-use. In the beach and sand dune habitats the sea-level rise is expected to cause a change in groundwater level, influencing slack vegetation, and a change in the erosion/accretion pattern, resulting in landward rebuilding of the mobile dune as well as in a more or less diffuse inland sand drift, causing destabilization of fixed dune vegetation.     

Modelling small groundwater systems: experiences from the Braunton Burrows and Ainsdale coastal dune systems,UK

Coastal dunes are delicate systems that are under threat from a variety of human and natural influences. Groundwater modelling can provide a better understanding of how these systems operate and can be a useful tool towards the effective management of a coastal dune system, e.g. by identifying strategically important locations for flora and fauna and guiding the planning of management operations through predicting impacts from climatic change, sea level rise and land use management. Most dune systems are small, typically of the size 10–100 km², compared with inland groundwater systems. Applying conventional groundwater modelling approaches to these small systems presents a number of challenges due to the local scale of the system and the fact that the system boundaries (sea, drains, ponds etc.) are close to the main body of the aquifer. In this paper, two case studies will be presented using different modelling approaches to understand the groundwater balance in two dune systems in the UK. The studies demonstrate that, although conventional hydraulic models can describe the general system behaviour, a fuller understanding of the recharge mechanisms and system boundaries is needed to represent adequately system dynamics of small groundwater systems.     

Coastal livelihoods,poverty and well-being in Mexico. A case study of institutional and social constraints

The aim of this study is twofold. First, it explores the local discourses of poverty and well-being in a fishing community in Baja California Sur, Mexico. Second, the study examines the several constraints that fishers face for secure and sustainable livelihoods. The assessment used the sustainable livelihoods framework as analytical approach. The study concluded that poverty and marginalization in this fishing community is closely linked with institutional and social factors rather than to economics issues. The most severe constraints observed were corruption in the allocation of fishing licenses and permits, social exclusion and marginalization of new settlers and domestic violence associated with alcoholism and drug addictions. The current discourse that explains poverty exclusively in economic terms is discussed largely and confronted with empirical evidence. Finally, the study emphasizes the necessity to implement a marine protected area in the region, with the aim to preserve the marine resources as well as to establish a normative framework which guarantees transparency and justice in the resources allocation.     

Distribution and abundance of the epipelagic mollusk Carinaria japonica in waters off Southern California

The distribution and abundance of the heteropod mollusk Carinaria japonica Okutani is described from midwater trawl records off Southern California (USA) and northern Baja California (Mexico). Maximal numbers of individuals were recorded during August in oceanic waters off Southern California. In oceanic waters near Guadalupe Island, Baja California, low population levels were recorded irrespective of season. In neritic waters over the continental shelf off Southern California, C. japonica were present in low numbers, mainly between July and December when conditions seemed most favorable for their entry into the Southern California Eddy.     

The effect of land clearing on rainfall and fresh water resources in Western Australia: a multi-functional sustainability analysis

It is widely recognised that southwest Western Australia has experienced a decline in rainfall over the last 40 years. It is generally thought that this decline is due to natural periodic variations and changes induced by global warming, but recently evidence has emerged suggesting that a substantial part of the decline may be due to extensive logging close to the coast to make way for housing developments and the clearing of native vegetation for wheat planting on the higher ground. We compare coastal and inland rainfall to show empirically that 55% to 62% of the observed rainfall decline is the result of land clearing alone. Using the index of sustainable functionality, we show that the economic consequences associated with this change of land use on fresh water resource availability have been underestimated to date and disproportionately affect the environment and poorest members of the population.     

Conservation and management-oriented ecological research in the coastal zone of Baja California, Mexico

This paper presents the main results of two studies of contrasting natural and man-induced conditions along the Pacific coast of Baja California (Mexico), based on the assumption that ecological insight can be obtained from man-induced modifications insofar as relevant activities are explicitly addressed as parts of the systems under study. The study is concerned with a fragmented coastal succulent-sage scrub and showed that several patches of different size and age may harbor as many species as non-fragmented areas, and that 83% of the original species assemblage persisted in the fragments, in which the invasion by opportunistic exotic species may not progress beyond certain limits. The study of dune-backed and urban-backed beaches showed a significantly greater abundance of the Snowy Plover (Charadrius alexandrinus) at the dune-backed beach, where a much more active back-shore feeding of adult birds and the only evidences of breeding occurred. Both studies refer to landscape features of regional concern and its results may be used in conservation management. The results on fragmented coastal succulentsage scrub may encourage alternative urban designs that keep patches of the original landscape, thus meeting existing requirements of low density urban development for most of the coastal succulent-sage scrub area. The evidence presented on the negative effects of dune destruction on the abundance, feeding and reproductive performance of a threatened bird species has a bearing on the topic of biodiversity management. It may also contribute to the conservation of the coastal dunes system.     

Measurements of fog water interception by shrubs on the California central coast

Fog water deposition may be an important component of the water budget of herbaceous-shrub ecosystems on the central and southern coastal regions of California. This paper presents the first analysis of measured fog water drip rates and meteorological controls in shrublands of Big Sur, California. Seasonal totals of 1255 mm and 306 mm of fog water drip were recorded in 2014 and 2015 (respectively), for averaged fog deposition rates of 0.02–0.08 l m² hr.^?1 to the soil under shrub canopy cover. The diurnal patterns of fog water drip showed that the majority of all trough water collected under shrubs on no-rain days occurred between the hours of 11 PM and 9 AM. During the study period from June 1 to October 31 of both 2014 and 2015, soil water content decreased significantly from average levels of 4–6 % at the shrub canopy center and middle locations, through 2–3 % VWC at the shrub edge locations, to levels at or below 2 % at 2-m distance locations from the shrub edge in open grass cover. Based on these results, we conclude that detectable rates of shrub canopy fog interception help sustain elevated soil water levels under shrubs and aid woody vegetation survival through periods of low rainfall.     

Geographical subdivision,demographic history and gene flow in two sympatric species of intertidal snails, <Emphasis Type="Italic">Nerita scabricosta</Emphasis> and <Emphasis Type="Italic">Nerita funiculata</Emphasis>, from the tropical eastern Pacific

The patchy distribution of rocky intertidal communities in the tropical eastern Pacific (TEP) may impose severe constraints on the genetic connectivity among populations of marine invertebrates associated with this habitat. In this study, we analyzed a portion of the mitochondrial cytochrome c oxidase subunit I (COI) gene in two sympatric species of marine snails, Nerita scabricosta and Nerita funiculata, common inhabitants of the rocky intertidal from the Gulf of California (Sea of Cortez) and outer Pacific coast of the southern Baja California (Baja) peninsula to northern South America, to assess genetic connectivity among populations of each species. One of our aims was to determine whether the morphological, behavioral, and ecological differences observed among populations of both species throughout their range in the TEP corresponded to population genetic differences. In addition, we were interested in elucidating the demographic history of both species. We found no evidence of genetic structure throughout the Gulf of California and outer coast of the Baja peninsula region for either species. Comparisons between Gulf of California/Baja and Panama populations, however, showed significant genetic differentiation for N. scabricosta, but not for N. funiculata. The genetic differences between Mexican and Panamanian populations of N. scabricosta were consistent with previously reported ecological and behavioral differences for this species between these two distant regions. However, previously reported size differences between northern and central/southern Gulf of California individuals of N. scabricosta do not correspond with our findings of genetic connectivity among these populations. Results from neutrality tests (Tajima’s D and Fu’s F _S), the mismatch distribution, and Bayesian skyline analyses suggested that both species have experienced dramatic population expansions dating to the Pleistocene.