Mangroves as Fish Habitat

2015 ◽  
Keyword(s):  
Growth Rates ◽  
Fish Habitat ◽  
Individual Growth ◽  
Baja California Sur ◽  
Bivalve Species ◽  
Anthropogenic Pressures ◽  
La Paz ◽  
Frequency Distributions ◽  
Mass Increment ◽  
Secondary Productivity

<em>Abstract</em>.—To measure secondary productivity of mangrove systems, we estimated the abundance (individuals/m<sup>2</sup>) and mass increment (g/month) of the two bivalve species: the black ark <em>Anadara tuberculosa </em>and palmate oyster <em>Saccostrea palmula</em>. Mass increments were based on individual growth rates derived from length-frequency distributions analyses. Samples were collected at three mangrove estuaries in a sand barrier at Ensenada de La Paz from August 2007 to July 2009. The average abundance was 1.27 individuals/m<sup>2</sup> for black ark and 510 individuals/m<sup>2</sup> for palmate oysters. Estimated growth rates were 3.67 g/month for black ark and 0.18 g/month for palmate oysters. The average secondary productivity of the black ark was 4.51 g•m<sup>-2</sup>•month<sup>-1</sup> and peaked during the spring, while for the palmate oyster <em>Saccostrea palmula </em>it was 97.9 g•m<sup>-2</sup>•month<sup>-1</sup>, with peak productivity recorded during the summer. The findings of this investigation constitute a necessary element for establishing a baseline to evaluate the consequences of the various natural and anthropogenic pressures that the mangrove systems of El Mogote of La Paz Bay, Baja California Sur, Mexico.

Género, institucionalismo y marginalidad: la gestión del agua de uso doméstico como desafío para el empoderamiento de las mujeres. El caso de la ciudad de La Paz, Baja California Sur, México

2018 ◽  
pp. 175-199
Author(s):  
Lorella Castorena Davis ◽  
Arely Madai Martínez Valencia
Keyword(s):  
Baja California ◽  
Baja California Sur ◽  
La Paz ◽  
Las Mujeres

El objetivo de este artículo es analizar la persistencia de la división tradicional del trabajo doméstico. La escasa valoración de las actividades de reproducción de la vida, como la maternidad, y el cuidado y atención a otras personas, sumada a condiciones de marginalidad, derivan en un incremento de las cargas de trabajo y reducen las probabilidades de empoderamiento de las mujeres. Asimismo la mala distribución de recursos como el agua, junto con su escasez y deficiente calidad, se tornan en obstáculos para alcanzar la igualdad de género. El vínculo teórico entre género, institucionalismo y marginalidad, así como la selección del caso de estudio, representan los aportes más relevantes de este trabajo, en tanto permiten mostrar el impacto que el funcionamiento de la institución encargada de la distribución del agua tiene sobre las mujeres, en la medida que refuerza el hábito y la norma cultural que las responsabiliza de resolver el abasto de agua al interior de sus hogares. Se analiza la problemática de género que enfrentan mujeres jefas de familia respecto al agua de uso doméstico en cinco colonias marginadas de la ciudad de La Paz, en las que se aplicó un total de 42 cuestionarios gracias a los cuales se concluyó que las mujeres jefas de hogares marginados además de la sobrecarga de trabajo doméstico y de cuidados derivados del abasto insuficiente y deficiente de agua que provee el organismo operador, deben enfrentar los costos derivados tanto del conjunto de diligencias cotidianas que realizan para garantizar que el agua que reciben alcance para satisfacer sus necesidades mínimas, como del gasto que representa el consumo de agua embotellada proveniente de las plantas purificadoras locales o de barrio.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

Wintertime growth in Atlantic salmon under changing climate: the importance of ice cover for individual growth dynamics

2021 ◽  
Author(s):  
Laura Härkönen ◽  
Pauliina Louhi ◽  
Riina Huusko ◽  
Ari Huusko
Keyword(s):  
Climate Change ◽  
Atlantic Salmon ◽  
Growth Rates ◽  
Growth Dynamics ◽  
Ice Cover ◽  
Individual Growth ◽  
Late Winter ◽  
Dynamic Nature ◽  
Individual Level ◽  
Growth Variation

Understanding the dynamic nature of individual growth in stream-dwelling salmonids may help forecast consequences of climate change on northern fish populations. Here, we performed an experimental capture-mark-recapture study in Atlantic salmon to quantify factors influencing wintertime growth variation among juveniles under different scenarios for ice cover reduction. We applied multiple imputation to simulate missing size observations for unrecaptured fish, and to account for individual-level variation in growth rates. The salmon parr exhibited substantial body length shrinkage in early winter, suppressed growth through mid-winter, and increasing growth rates in late winter and particularly in spring. Unexpectedly, the presence of ice cover had no direct effects on wintertime growth. Instead, our results implied increasing energetic costs with reducing ice cover: individuals exposed to absent or shortened ice-covered period gained mass at a lowered rate in spring whereas the present, long ice-covered period was followed by rapid growth. This study emphasizes natural resilience of Atlantic salmon to wintertime environmental variation which may help the species to cope with the reductions in ice cover duration due to climate change.

Age, stucture, growth rates and movements of sea mullet, Mugil cephalus L., and Yellow-eye Mullet, Aldrichetta forsteri (Valenciennes), in the Swan-Avon river system, Western Australia

1981 ◽  
Vol 32 (4) ◽  
pp. 605 ◽  
Author(s):  
CF Chubb ◽  
IC Potter ◽  
CJ Grant ◽  
RCJ Lenanton ◽  
J Wallace
Keyword(s):  
Growth Rates ◽  
River System ◽  
First Year ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Using Data ◽  
The Times ◽  
First Year Of Life ◽  
Breeding Seasons ◽  
System 1

The age structure, growth rates and movements of M. cephalus and A forsteri in the Swan-Avon river system have been investigated using data obtained from beach seining and gill netting carried out between February 1977 and June 1980. Length-frequency data and scale readings show that the populations of both species consist predominantly of 0+ and 1 + fish. From the times when the smallest fry (20-30 mm) were present in the lower part of the river system, and from the condition of the gonads of older fish, the breeding seasons of the sea and yellow-eye mullets have been estimated as extending from March to September and from March to August respectively. The bimodality or polymodality exhibited by the length-frequency distributions for the 0 + year classes suggest that in both species groups of individuals spawn at slightly different times. The range of mean total lengths and weights of animals caught in May near the end of the first year of life was 178-222 mm and 64-119 gin M. cephalus and 136-154 mm and 19-30 g in A. forsteri, which shows that the growth of each of these two species of mullet is relatively very rapid in the Swan-Avon river system. 1 + and 2 + fish tend to leave the estuary for varying periods. Although 0+ fish of both species utilized the shallow banks of the estuary throughout the year. the sea mullet moved further upstream and were not as consistently abundant in the lower estuary. Since 0+ yellow-eye mullet 40-100 mm long were also abundant in marine coastal waters between January and May. and sea mullet of comparable age were rarely observed in these regions, it would appear that M. cephalus is the more estuarine-dependent of the two species. Commercial catches of M. cephalus were greater than those of A. forsteri. This feature can be related in part to the much faster growth rate of M. cephalus, which results in a larger proportion of its youngest year classes reaching the minimum legal size for capture prior to the time when they leave the estuary in large numbers.

scholarly journals Evaluación de los recursos de radiación solar en los municipios de Baja California Sur, México, mediante un modelo de aptitud socioambiental

2020 ◽  
Vol 32 ◽  
pp. e1296
Author(s):  
Pedro Daniel Molina Pfennig ◽  
Arturo González-Baheza
Keyword(s):  
Baja California ◽  
Baja California Sur ◽  
La Paz ◽  
Toma De Decisiones ◽  
La Red

El objetivo del trabajo es evaluar el índice de aptitud de los municipios de Baja California Sur para la instalación de concentradores fotovoltaicos. La metodología propone un modelo de aptitud que incorpora seis indicadores socioambientales explícitos en términos espaciales con asignación de su contribución diferenciada o pesos por medio de análisis multicriterio. Los resultados muestran que la irradiación horizontal anual promedio en Baja California Sur es de 6.19 kW h/m2/día en el periodo 1998-2014. De la superficie total en el estado, 5.25% es viable para la instalación de concentradores fotovoltaicos. Comondú, Mulegé y La Paz presentaron los mayores valores de aptitud. Los indicadores predominantes del modelo son la red carretera, la red eléctrica y las zonas con pendientes de ˂4°. El estudio se limitó a analizar la influencia de los indicadores socioambientales en la ubicación de sistemas de concentradores fotovoltaicos. La metodología podría replicarse en otras regiones para facilitar la toma de decisiones. Los resultados sugieren que los tres municipios de Baja California Sur mencionados son los más favorables en términos socioambientales para la instalación de dichos concentradores.

Creole cattle from northwestern Mexico has high genetic diversity in the locus DRB3.2

2015 ◽  
Vol 57 ◽  
pp. 31-38
Author(s):  
I.G. Fernández ◽  
I. Leyva-Baca ◽  
F. Rodríguez-Almeida ◽  
R. Ulloa-Arvizu ◽  
J.G. Ríos-Ramírez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Baja California ◽  
The State ◽  
Baja California Sur ◽  
High Genetic Diversity ◽  
La Paz ◽  
Separate Branch ◽  
Pcr Rflp ◽  
Creole Cattle ◽  
Northwestern Mexico

SummaryThe objective of this study was to determine the genetic diversity of creole cattle in northwestern Mexico using the BoLA-DRB3.2 locus of the Major Histocompatibility Complex (MHC). A total of 56 creole cattle were sampled from five communities; in the state of Chihuahua (Cerocahui, Guadalupe y Calvo and Cuauhtémoc) and in the state of Baja California Sur (La Paz and Mulegé). The BoLA-DRB3.2 locus was genotyped by PCR-RFLP assay. Thirty-nine alleles were identified, out of which 14 had not been previously reported. The average level of inbreeding in all populations analyzed wasFIS= 0.09 (P&lt; 0.0001), but only two populations (Cerocahui and Guadalupe y Calvo) showed an excess of homozygotes (P&lt; 0.05). The breed differentiation in all populations studied wasFSC= 0.068 (P&lt; 0.0001). The smallest genetic distance was between La Paz and Mulegé (0.022); but Mulegé presented smaller distances (0.028–0.053) with the populations of La Paz (0.071–0.083) and with Chihuahua. Baja California Sur populations are grouped in a separate branch than Chihuahua populations. We conclude that creole cattle from Baja California Sur and Chihuahua show high genetic diversity in the locus BoLA-DRB3.2.

Composición botánica del matorral sarcocaule en Baja California Sur durante las estaciones húmeda y seca

2020 ◽  
Vol 11 (61) ◽  
Author(s):  
Emanuel Junco Carlón ◽  
Humberto Gonzalez Rodriguez ◽  
Jose Angel Armenta Quintana ◽  
Israel Cantu Silva ◽  
Andres Eduardo Estrada Castillon ◽  
...  
Keyword(s):  
Baja California ◽  
Baja California Sur ◽  
La Paz ◽  
Turnera Diffusa ◽  
Para Determinar

El objetivo del presente estudio fue determinar la composición florística del matorral sarcocaule del desierto sonorense en un área de 800 ha dentro de una propiedad ejidal ubicada en los límites de la ciudad de La Paz, Baja California Sur. El muestreo se realizó durante la época de lluvias (septiembre-noviembre de 2018) y a finales de la épocade sequía (mayo-agosto de 2019), por medio de 20 cuadrantes de 5 m × 5 m. Se identificaron 29 especies de 1 634 individuos, entre las dos temporadas y se consideraron las variables de altura y diámetro de copa de cada ejemplar por especie, para determinar abundancia (Ar), dominancia (Dr), frecuencia (Fr), índice de valor de importancia (IVI) y los índices de Shannon para la diversidad de especies (H´) e índice de Margalef para la riqueza de especies (S´). Durante la época de lluvias, se observó a Jatropha cinerea como dominante Dr=7.15 % y con mayor IVI (10.7 %);  Turnera diffusa fue la más abundante con Ar=3.2. En cambio, para la temporada seca, fue Prosopis articulata la especie dominante Dr=9.29 y con mayor IVI (12.51 %); Mammillaria armillata fue la más abundante, con Ar=4.56. Los índices de (H’) y (S’) durante la época de lluvias fueron 3.36 y 8.09, respectivamente, con diferencia entre ellos (p≤0.05) al compararlos con los de la temporada seca (2.88 y 4.88, respectivamente), debido a la ausencia de taxones y disminución del número de individuos, en relación con la época húmeda.

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