Universidade da Coruña. UDCDspace
(405 recursos)
UDCDspace é o repositorio dixital da Universidade da Coruña, un sistema que proporciona de xeito estable e seguro a preservación de documentos dixitais produto da actividade científica e institucional da UDC, e facilita a súa accesibilidade en Internet.
Mostrando recursos 1 - 20 de 20
1.
Predicting changes to macrobenthic communities due to fishing disturbance in a shrimp fishing ground of the Mexican central Pacific - Godínez Domínguez, Enrique; Freire Botana, Juan Manuel; González Sansón, Gaspar
We test predicted short-term structural changes in the macroinvertebrate
assemblages of a shrimp fishing ground in the tropical Mexican Pacific subject to
low effort with seasonal closures. During two years, five cruises were carried out
sampling seven sites and four depths (20, 40, 60 and 80 m) along 100 km of
coastline. A series of community structure descriptors were used to determine the
ecological effects of fishing disturbances: ABC curves, W-statistic, normalized
species size distribution as biomass spectra, spatial segregation index, Shannon-
Wiener diversity index, species richness and biomass. Theoretical predictions of the
effects of fishing on these indices were tested by comparisons of samples collected
from successive open...
8.
Decomposing diversity patterns of a soft-bottom
macroinvertebrate community in the tropical eastern Pacific - Godínez Domínguez, Enrique; Freire Botana, Juan Manuel; Franco Gordo, María Carmen; González Sansón, Gaspar
Diversity is one of the most frequently used attributes of ecological
communities, and there is a long-standing discussion about their adequate use,
calculus and interpretation. One of the most conspicuous and simple diversity
estimators is species richness, but it has been criticized by recurrent pitfalls, which has
biased comparisons and the testing of hypotheses. Otherwise, synthetic ecological
indices of diversity are difficult to interpret due the underlying complex or cryptic
concepts. Most of the studies in soft-bottom macroinvertebrate communities trying to
estimate richness species, have actually quantified species diversity as species
density, the number of species per unit area. In the present study, the diversity of a
tropical Pacific...
9.
Interannual variability of the diversity and structure
of ichthyoplankton assemblages in the central Mexican Pacific - Franco Gordo, María Carmen; Godínez Domínguez, Enrique; Freire Botana, Juan Manuel
We examined larval fish diversity and assemblage structure on the central
Mexican Pacific (coast of Jalisco and Colima) using data from samplings carried
out with a Bongo net at 12 stations during 27 months, from December 1995
through December 1998. A total of 132 taxa were recorded, and the dominant
species were Bregmaceros bathymaster (90% of the total abundance),
Dormitator latifrons (1.9%) and Harengula thrissina (0.8%). Only B.
bathymaster, D. latifrons and Gobionellus sp. attained the 100 % of occurrence.
The effects of the 1997-98 El Niño event in ichthyoplankton diversity were
significant, however the prevalence of the normal seasonality could be
observed. Diversity null models were used to...
10.
Inter-specific comparative analysis of distribution and habitat use patterns
of benthic decapod crustaceans in shallow waters - Pallas Lozano, Alicia; García Calvo, Beatriz; Corgos López-Prado, Antonio; Bernárdez Martí, Cristina; Freire Botana, Juan Manuel
Coastal areas have been widely considered as nurseries for many marine
species. New approaches to this concept take into account interactions among
environmental variables and ecological variations related to geographical location, as
well as complex life cycles of marine invertebrates. We present a comparative approach
to assess the relevance of environmental variables on the determination of patterns of
distribution and habitat use of benthic decapod species in coastal areas. We
hypothesize that this approach allows us to infer processes originating these patterns
and to identify the main habitat use models. An intensive fine-grain sampling design
was used to take into account the environmental gradients occurring at different spatial
scales...
11.
Morphometric and gonad maturity in the spider crab "Maja brahcydactyla". A
comparison of methods for the estimation of the size at maturity in species with determinate growth - Corgos López-Prado, Antonio
Ontogenetic changes in the relative growth of males and females of the spider crab
Maja brachydactyla, a species with terminal moult and determinate growth, were
analyzed and related to their reproductive (maturity) status. Sampling was carried out in
the Ría de A Coruña (NW Spain) from December 1997 to November 1999. A
combination of principal component analysis of morphometric variables, nonhierarchical
K-means cluster and discriminant analysis allowed to differentiate two
morphometric groups of males defined as juvenile and adult phases and develop
statistical methods to assign maturity status to individual crabs. A significant change in
allometry of cheliped size was detected in juvenile males with a breakpoint at...
12.
Complex patterns of habitat use by juvenile spider crabs "Maja
brachydactila" revealed by stable isotope analyses - Freire Botana, Juan Manuel; Carabel Chans, Sirka; Verísimo Amor, Patricia; Bernárdez Martí, Cristina; Fernández Rodríguez, Luis José
Patterns of habitat use by spider crab juveniles, Maja brachydactila, from two geographic
areas in the NW coast of the Iberian Peninsula, were analyzed through the analysis of Carbon
and Nitrogen stable isotope relations in two tissues (muscle and hepatopancreas). The main
organisms that constitute the diet of spider crab juveniles in rocky and sandy habitats and the
different organic matter sources in coastal food webs were analysed too. The isotopic ratios
of C and N did not show any difference between habitats. The use of carapace colour and
epibiosis as an indicator of habitat use was not supported by our data. These results suggest
much more...
13.
Inter-specific comparative analysis of distribution and habitat use patterns
of benthic decapod crustaceans in shallow waters - Pallas Lozano, Alicia; García Calvo, Beatriz; Corgos López-Prado, Antonio; Bernárdez Martí, Cristina; Freire Botana, Juan Manuel
Coastal areas have been widely considered as nurseries for many marine
species. New approaches to this concept take into account interactions among
environmental variables and ecological variations related to geographical location, as
well as complex life cycles of marine invertebrates. We present a comparative approach
to assess the relevance of environmental variables on the determination of patterns of
distribution and habitat use of benthic decapod species in coastal areas. We
hypothesize that this approach allows us to infer processes originating these patterns
and to identify the main habitat use models. An intensive fine-grain sampling design
was used to take into account the environmental gradients occurring at different spatial
scales...
14.
Estacionalidad de la muda terminal y la migración reproductiva en la centolla, "Maja brachydactyla" : evidencias de estrategias de apareamiento alternativas - Corgos López-Prado, Antonio; Verísimo Amor, Patricia; Freire Botana, Juan Manuel
Se analiza la temporalidad y sincronización de los procesos de muda terminal, maduración gonadal, acumulación de reservas energéticas y migración en la centolla, Maja brachydactyla, tanto a nivel individual como poblacional, y su variabilidad intra- e intersexual. Para explicar esta variabilidad en la temporalidad se plantean dos hipótesis: 1) hipótesis fisiológica: machos y hembras inician la migración cuando alcanzan un estado fisiológico adecuado (un nivel de reservas energéticas óptimo), y 2) hipótesis de oportunidades de apareamiento: la temporalidad de la migración trataría de maximizar las oportunidades de apareamiento y la calidad de las parejas. Nuestros resultados muestran que los machos...
15.
Growth at moulth, intermoult period and moulting seasonality of the spider crab "Maja brachydactyla" : combining information from mark-recapture and experimental studies - Corgos López-Prado, Antonio; Sampedro Pastor, María Paz; González Gurriarán, Eduardo; Freire Botana, Juan Manuel
An analysis of growth at moult (for both the prepubertal and terminal moults),
moulting seasonality and the intermoult period in the spider crab Maja squinado in
the Ría de A Coruña (NW Spain) was carried out based on a mark-recapture
experiment. Crabs between 70 and 130 mm carapace length (CL) undergo a mean
increase at moult of 32.4% from their pre-moult size. Generalised Linear Models
(GLMs) were used to construct growth models, employing a combination of
information from the mark-recapture study and other previous studies performed in
both laboratory and extensive culture, to estimate the effects of the biological
variables and the study method. No differences were found...
16.
Interactions of the fishery of the spider crab Maja squinado with mating,
reproductive biology and migrations - Freire Botana, Juan Manuel; Fernández Rodríguez, Luis José; González Gurriarán, Eduardo
In this paper different aspects of the fishery and life history of the spider crab Maja squinado
in southern Galicia (NW Spain) are analyzed to evaluate the potential effects of the fishery
on the sperm limitation of the reproductive effort (egg production) of the population.
Juveniles of the spider crab inhabit shallow waters, where they carry out a terminal
moult in August-September, attaining sexual maturity when they are 2+ years old. A short
time after the terminal moult (October-November), adults migrate to deeper waters (up to
100 m), where mating occurs (January-February). Field and laboratory data show that
multiple matings and sperm storage in female seminal receptacles...
17.
Exploring long-term variability of Nephrops norvegicus population and fishery off
North Galicia (NW Spain) - Fariña Pérez, Antonio Celso; González Herraiz, Isabel; Freire Botana, Juan Manuel; Cancelo de la Torre, José Ramón
Variability in the catch per unit effort (CPUE) of Nephrops norvegicus from North
Galicia (Northwest Spain) was investigated by using time series approach. The CPUE
time series (1975-2001) exhibited a seasonal pattern. The seasonal decomposition of the
CPUE showed a declining trend in the trend and cycle compone nt from 1987 onwards.
ARMA univariate and dynamic regression models were fitted to the CPUE time series.
Population (proportion of males, proportion of ovigerous females and recruits) and
environmental variables (temperature, salinity, nitrates and chlorophyll at 70 m depth,
upwelling and surface sea temperature) were tested at different lags. The proportion of
males 4 years ago and the current surface...
19.
An assessment of sample processing methods for stable isotope analyses of coastal foodwebs - Carabel Chans, Sirka; Godínez Domínguez, Enrique; Verísimo Amor, Patricia; Fernández Rodríguez, Luis José; Freire Botana, Juan Manuel
The relative abundance of the light and heavy forms of stable isotopes of Carbon and
Nitrogen is commonly used in the research of marine food webs. Dehydration of
samples is needed for C and N isotopic analysis, and in those organisms with inorganic
carbonate structures acidification with hydrochloric acid is also needed for sample
preparation. There is not a consensus about the methodology appropriate for sample
processing. In the present study, the effects of different sample processing methods in
the relative abundance of stable isotopes of C and N in the different trophic
compartments of a coastal food web are evaluated. The final purpose is to define...
20.
Complex patterns of habitat use by spider crabs Maja squinado revealed by stable isotope analyses - Freire Botana, Juan Manuel; Carabel Chans, Sirka; Verísimo Amor, Patricia; Bernárdez Martí, Cristina; Fernández Rodríguez, Luis José
Patterns of habitat use by spider crab juveniles, Maja brachydactila, from two geographic
areas in the NW coast of the Iberian Peninsula, were analyzed through the analysis of Carbon
and Nitrogen stable isotope relations in two tissues (muscle and hepatopancreas). The main
organisms that constitute the diet of spider crab juveniles in rocky and sandy habitats and the
different organic matter sources in coastal food webs were analysed too. The isotopic ratios of C and N did not show any difference between habitats. The use of carapace colour and
epibiosis as an indicator of habitat use was not supported by our data. These results suggest
much...
1.
