Papers by Leonardo Castro
Patrones de distribución, crecimiento larval y fecha de eclosión de los estados tempranos del mot... more Patrones de distribución, crecimiento larval y fecha de eclosión de los estados tempranos del mote Normanichthys crockeri (Scorpaeniformes, Normanichthyidae) en el ecosistema de surgencias de Chile central
Frontiers in Marine Science, 2021
The Southern Ocean plays a major role in the Earth’s climate, provides fisheries products and hel... more The Southern Ocean plays a major role in the Earth’s climate, provides fisheries products and help the maintenance of biodiversity. The degree of correspondence between physical and biogeochemical spatial variability and regionalization were investigated by calculating the main physical factors that statistically explained the biogeochemical variability within the Southern Ocean and the 48.1 zone of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The mean value of physical and biogeochemical variables was estimated during austral summer within a grid of 1° × 1° south of 50°S. The regionalization was developed using both non-hierarchical and hierarchical clustering method, whereas BIO-ENV package and distance-based redundancy analysis (db-RDA) were applied in order to calculate which physical factors primarily explained the biogeochemical spatial variability. A total of 12 physical and 18 biogeochemical significant clusters were identified for the S...
análisis y post-proceso data acústica, análisis estadístico; jefe de crucero. Jefe de crucero; an... more análisis y post-proceso data acústica, análisis estadístico; jefe de crucero. Jefe de crucero; análisis y post-proceso data acústica. Coordinación y diseño muestreo y análisis biológico; coordinación logística cruceros; estimación TS ex situ.; elaboración de informes. Michael Soule Diseño y pruebas sistema hidroacústico de profundidad; análisis de TS in situ. Asistente muestreo acústico; análisis data acústica; administrador base de datos; análisis estadístico. Experto hidroacústica; análisis TS in situ. Coordinador muestreo biológico a bordo; apoyo base de datos; postproceso data acústica.
Frontiers in Marine Science, 2021
In southern Patagonia, the Beagle Channel shows very low production during winter but simultaneou... more In southern Patagonia, the Beagle Channel shows very low production during winter but simultaneously sustains very dense aggregations of the pelagic stage of squat lobster (Munida gregaria), a benthic decapod whose pelagic juveniles have the largest body size within the chitinous pelagic community. To assess the coexistence of the mesozooplankton community and the pelagic M. gregaria stage under the harsh feeding winter conditions, we conducted a research cruise at two locations connected to the Beagle Channel, Yendegaia Bay (land terminating-glacier) and Pia Fjord (marine-terminating glacier). Our results showed that the zooplankton communities were similar in these two fjords, that a single pelagic group dominated in terms of biomass (pelagic Munida gregaria), and that differences in vertical distribution existed between most of the principal crustacean zooplankton and pelagic M. gregaria. All groups showed consumption of terrestrially derived organic matter, as revealed by their ...
Estuaries and Coasts, 2018
Glacial lake outburst floods (GLOFs) in Northern Patagonian Ice Field affecting the Baker River b... more Glacial lake outburst floods (GLOFs) in Northern Patagonian Ice Field affecting the Baker River basin have increased their frequency in recent years. To evaluate the impact of a GLOF in the hydrography and biological components of the plankton in the Baker Fjord, we assessed the relative contributions of terrigenous versus marine plankton carbon sources to the particulate organic matter (POM) in the fjord before and after a GLOF in the austral summer 2014. We also evaluated whether terrestrial carbon brought into the fjord by the river may reach higher trophic levels via a deposit-feeding organism the juvenile pelagic Munida gregaria. Over a 10-day period, hydrographic profiles, water samples for POM, and zooplankton samples were collected daily from three stations and two depths along the fjord's inner section. Samples of suspended POM and tissue from M. gregaria were analyzed for stable-isotope composition of carbon (δ 13 C) and nitrogen (δ 15 N). The GLOF arrival produced a thermal front in the fjord, followed by an oscillation of the pycnocline; an abrupt increase in the total organic carbon content of POM, which was attributed to terrestrial input; and a concurrent peak in the abundance of M. gregaria, suggesting an aggregation response to the GLOF. Understanding GLOF effects on local hydrography, productivity, and food web structure provides valuable insight on the potential responses of fjord ecosystems in general to climate change-induced variability. Given present climatic trends in highlatitude zones, more frequent GLOFs might be expected in Patagonian fjords and channels as well as in other high-latitude basins.
Revista de biología marina y oceanografía, 2016
The finding of a late flexion cetomimid specimen of 24.6 mm body length (BL), plus a caudal strea... more The finding of a late flexion cetomimid specimen of 24.6 mm body length (BL), plus a caudal streamer of 5.7 mm, collected in the southeastern Pacific near the Juan Fernandez seamounts (33.565°S; 77.710°W), is reported. The specimen was in good condition, almost fully pigmented, covered by small melanophores from the head to the caudal streamer, where the pigmentation is denser. It possesses an upturned mouth, developing pelvic fins with a high insertion, 14 dorsal and 15 anal fin rays, 7+7 principal caudal fin rays, ca. 54 myomeres, and a preanal distance of 75% BL. Based on the available information, the specimen can be tentatively ascribed to a species of Gyrinomimus or Cetomimus.
Latin American Journal of Aquatic Research, 2014
During 2010 several massive salp outbreaks of the Subantarctic species Ihlea magalhanica were rec... more During 2010 several massive salp outbreaks of the Subantarctic species Ihlea magalhanica were recorded in the inner sea of Chiloé Island (ISCh, Southern Chile), affecting both phytoplankton abundance and salmon farmers by causing high fish mortality. First outbreaks were recorded during February 2010 when Ihlea magalhanica reached up to 654,000 ind m-3 close to the net pens in Maillen Island and consecutive outbreaks could be followed during March and from October to November 2010. One month prior to the first recorded salp outbreak, the adjacent oceanic region and ISCh showed a sharp decline of ca. 1.0ºC in sea surface temperature and an atypical pattern of oceanic sea surface currents, changing from a predominantly meridional (northward) to a zonal (eastward) direction, probably causing a massive Subantarctic Water parcel to enter the ISCh. During the outbreaks, surface chlorophyll concentration decreased from an historical mean of 13.8 to less than 4 mg Chl-a m-3 , and did not return to normal conditions throughout the entire year, and similar results were also observed in phytoplankton abundance. The abundance of salp aggregations were highest close to the salmon net pens, which acted as physical barriers, and may have favored the successful reproduction and persistence of the outbreaks during 2010. The possible impact of these outbreaks on phytoplankton quality and quantity, as well as potential scenarios for the development of further outbreaks is discussed.
Scientia Marina, 2019
The anchoveta (Engraulis ringens) is widely distributed throughout the Humboldt Current (4°30′-44... more The anchoveta (Engraulis ringens) is widely distributed throughout the Humboldt Current (4°30′-44°S). In recent years, its eggs and larvae have also been found inside fjords and channels of northern Patagonia, close to the southern limit of the central-south Chilean fishery zone. Currently, it is unclear whether these southern individuals constitute an independent subpopulation. This study analysed the elemental composition of otoliths from 102 specimens from central Chile and northern Patagonia using laser ablation inductively coupled plasma mass spectrometry. The results indicated that the elemental composition of the otolith cores (Mg, Pb, Zn, Ba) differed significantly between sites, revealing the existence of two discrete spawning zones, one in central Chile and one in northern Patagonia. However, the low significant differences of elemental signatures of otolith edges suggest that either individuals from both areas move between spawning areas and mix at certain periods of the ...
Bulletin of Marine and Coastal Research, 2016
Twelve laboratory experiments to evaluate the egestion in short time periods at the herbivorous c... more Twelve laboratory experiments to evaluate the egestion in short time periods at the herbivorous copepod Eucalanus subtenuis, were carried out with the aim to obtain data about the morphometry, volume, faeces production rate and coprophagy index, as well as to detect some feeding strategy. Two feeding treatments with different phytoplankton size classes (measured as chlorophyll a concentration) were applied to the copepod: 0 -25 μm (pico and nanophytoplankton) and 25-85 μm (microphytoplankton). The food source was obtained from the surface water in the Caribbean central coast region, between February and May 2001. At copepods with mean total size of 1855.45 +/- 20.50 μm, faeces length fluctuated between 66.66 and 315 μm, being longer when copepods fed with smaller phytoplankton size. The faeces diameter ranged from 12.5 to 58.3 μm and the volume from 1.3x104 and 6.3x105 μm3. The egested faeces fluctuated between 0 and 1.52 faeces cop-1 and 0 and 2.10 faeces cop-1, for the two size fe...
Water, 2020
As a result of climate change, the frequency of glacial lake outburst floods (GLOF) is increasing... more As a result of climate change, the frequency of glacial lake outburst floods (GLOF) is increasing in Chilean Patagonia. Yet, the impacts of the flood events on the physics and biology of fjords is still unknown. Current velocities, density, in-situ zooplankton samples, and volume backscatter (Sv) derived from an acoustic profiler were used to explore the response of circulation and zooplankton abundance in a Patagonian fjord to GLOF events in 2010 and 2014. Maximum Sv was found both during the GLOFs and in late winter to early spring of 2010 and the fall and summer of 2014. The increase in Sv in late winter and spring of 2010 corresponded to multiple zooplankton species found from in-situ net sampling. In addition, diel vertical migrations were found during this seasonal increase both qualitatively and in a spectral analysis. Concurrently with zooplankton increases, wind forcing produced a deepening of the pycnocline. Zooplankton abundance peaked in the fjord when the pycnocline dep...
Arctic, Antarctic, and Alpine Research, 2018
It is relevant to understand the processes and factors that modulate the efficiency of the carbon... more It is relevant to understand the processes and factors that modulate the efficiency of the carbon pump throughout the ecosystem of Patagonian fjords. Spatial variability of primary productivity and bacteria-microplankton biomass was assessed in relation to inorganic nutrients and stratification across nearshore zones of southern Patagonia (50-53°S) in austral spring 2009. Estimates of primary productivity (300-500 mg C m −2 d −1) and phytoplankton biomass (9-180 mg chlorophylla m −2) were low at offshore and inshore waters. Synergistic effects of low silicic acid concentrations and poor light penetration because of salinity-driven stratification of glacier meltwater in springtime appeared to negatively affect phytoplankton carbon biomass and primary production in this sub-Antarctic region. The knowledge of the relative importance of nutrient sources and light is especially significant for Patagonian glacier-fjord systems that are expected to receive higher freshwater inputs and will be more stratified in the future.
Ciencia Y Tecnologia Del Mar Vol 35, 2014
Eggs and larvae of the common sardine, Strangomera bentincki, were studied in the inner waters of... more Eggs and larvae of the common sardine, Strangomera bentincki, were studied in the inner waters of the X and XI regions of Chile, in order to identify potential spawning and early stages retention areas. Egg, pre and post-flexion larval abundance data from the CIMAR Fiordos 12-2 (Spring, 2006) and CI-MAR Fiordos 13-2 (Spring, 2007) cruises were analyzed. During the CIMAR 12-2 cruise decreasing concentrations of eggs and pre-flexion larvae from the Reloncaví Fjord to the south (boca del Guafo) were found, post-flexion larvae occurred in higher abundances in the Corcovado Gulf and boca del Guafo. In the CIMAR 13-2 cruise, eggs were found in boca del Guafo and in inshore waters; larvae were also found mainly in boca del Guafo. The vertical distribution of larvae varied between cruises: during the CIMAR 12-2 cruise, the distribution of larvae suggests a deepening from inshore to offshore waters as they develop, however in the CIMAR 13-2 cruise this pattern was not clearly observed. overall, the results suggest a potential ontogenetic shift in distribution of the early life stages of Strangomera bentincki from inner areas where eggs were more abundant, towards areas of higher oceanic waters influence where more developed larvae (post-flexion) occurred, a pattern that co-occurs along with a variation in the vertical distribution of eggs and larvae of this species.
Latin American Journal of Aquatic Research, 2014
Neuromast morphology and distribution are characterized during early ontogeny of anchoveta (Engra... more Neuromast morphology and distribution are characterized during early ontogeny of anchoveta (Engraulis ringens) and common sardine (Strangomera bentincki). Although both species share morphological features, they show several differences during their early ontogeny, such as size at hatching and yolk absorption. Larvae were obtained from incubation of planktonic eggs (at 12°C), collected during the spawning season 2001 (August-September) at Coliumo Bay. The neuromasts were observed from hatching to 25 days, and the pattern of neuromast appearance, in newly hatched larva, until yolk absorption, was determined using Janus Green staining and scanning electronic microscope. Results showed a similar pattern of neuromast development in both species. At hatching, two pairs of neuromasts were observed in the cephalic area and 8-9 in the rest of the body, which increased to 19 pairs and to 30-39 pairs at a larval size of 11 mm, respectively. On the average, 12 hair cells per neuromast were counted, with little variation among neuromasts. The polarity of these hair cells was closest to multiple polarity. Neuromast positioning for both species, anchoveta and common sardine larvae, are similar to those of Engraulis mordax and Clupea harengus, respectively. The similar development pattern of these species seems to be related to similar functional constraints and close taxonomic affinity.
Investigaciones marinas, 2001
Revista de biología marina y oceanografía, 2010
Scientia Marina, 2001
Along the Chile-Peru eastern boundary current, the hake Merluccius gayi is the most common demers... more Along the Chile-Peru eastern boundary current, the hake Merluccius gayi is the most common demersal species occurring throughout a wide distribution range from 6°S through 47°S. Within this latitudinal range, two potential subspecies have been proposed: Merluccius gayi peruvianus from 6°S through 14°S (Espino et al., 1995) and Merluccius gayi gayi from 23°S through the 47°S (Aguayo, 1995). The main hake spawning areas off the centralsouth Chilean coast that are traditionally observed extend from Papudo through Valparaiso (32°30'S-33°00'S) and from Constitucion to south of the Talc
Marine Ecology Progress Series, 1991
For bay anchovy Anchoa m~tchilli, 3 life-history parameters were studied in Great South Bay durin... more For bay anchovy Anchoa m~tchilli, 3 life-history parameters were studied in Great South Bay during late spring and summer of 1987 and 1988: intensity of spawning, larval growth rates, and egg and larval mortality rates. Duratlon of peak spawning season was h~g h l y correlated (p < 0.01) with larval food abundance in the fleld (copepod nauplli + copepodite and adult cyclopolds + copepodlte calanoids), but not correlated with sallnlty or temperature Cohort mortality rates determined throughout the spawning season were lower in the middle of the peak spawning season (when food availability was maximum) and higher at the beglnlng and end of the spawning season Since the duratlon of the high mlcrozooplankton abundance is so short (4 to 5 wk) and because of the hlgh energy requirements of young bay anchovy, ~t is proposed that adult bay anchovy spalvn dunng the season of inaxlmum food availabil~ty thus e n h a n c~n g offspr~ng survival When the effects of the type of habitat were analyzed on a local scale, no difference was found between eelgrass and unvegetated areas In. (1) egg or larval density, (2) larval growth rates, (3) egg and yolk sac larvae mortalltles Mortality rates of older larvae (> 3 d old), however, were higher In eelgrass beds than in unvegetated areas. Slnce ~nlcrozooplankton abundances were not different among stations, Increased mortality rates in the vegetated areas seem to result from higher levels of predation This suggests that the hypothesis that vegetated areas are used as preferential zones for spawning and nursing may not be aplicable to bay anchovy When the 3 population parameters studled are considered on a latitudinal basis, it was found that (1) duration of spawning season In Great South Bay is among the shortest reported in the literature, and decreased with increasing latitude; (2) average mortality rates were similar to those reported for populations located at other areas; (3) average larval growth rates tended to be higher in Great South Bay in spite of the lower temperatures during the spawning season. Possible interrelationships among these trends in life-history traits are discussed, and future lines of research on population differentiation are proposed
Marine Ecology Progress Series, 2006
Early life stages of Engraulis ringens were reared from hatch until yolk exhaustion. We evaluated... more Early life stages of Engraulis ringens were reared from hatch until yolk exhaustion. We evaluated the effect of temperature on characteristics such as larval length and yolk volume at hatch, larval length at yolk absorption, duration of yolk-sac stage, yolk consumption rate and larval growth rate. Further, we determined the potential differences in these traits between populations located 13°o f latitude apart (Antofagasta 23°S, Talcahuano 36°S). The results showed that egg size had an effect on the larval length at hatch, initial yolk volume and larval length at yolk absorption, since the values obtained were always larger in larvae hatched from Talcahuano (from larger eggs) than from Antofagasta (smaller eggs). These characteristics were also modified by the rearing temperature. Duration of yolk-sac phase, yolk consumption rate and larval growth rate until yolk exhaustion showed high thermic dependence in both populations. However, these traits showed no difference between populations when larvae were reared at the same temperature in the range between 12 and 20°C, despite their initial difference in egg size. When extrapolated from the environmental conditions in each nursery area (i.e. 15°C Antofagasta and 12°C Talcahuano), our results suggest that the anchoveta populations from Talcahuano compensate for their lower larval growth rates by increasing their initial egg and hatch sizes, as they are larger than Antofagasta larvae at the end of the yolk-sac stage. This increased larval length should enhance their chances of survival under adverse environmental conditions, such as high turbulence, lower temperature and lower food availability during winter, which is typical of the anchoveta southern spawning area.
Marine Ecology Progress Series, 2007
The euphausiid Euphausia mucronata and anchoveta Engraulis ringens are extremely abundant key com... more The euphausiid Euphausia mucronata and anchoveta Engraulis ringens are extremely abundant key components of the pelagic community of the Humboldt Current, and utilize a large fraction of primary production in the euphotic zone. Despite the economic importance of the Peruvian anchoveta, little information exists on the causes of mortality during their early life stages. In this study we: (1) detected and quantified E. mucronata predation on anchoveta eggs in Northern Chile during the winter peak spawning season of 2000 using enzyme-linked immunosorbent assay (ELISA); and (2) estimated the fraction of total natural mortality of anchoveta eggs produced by euphausiid predation. Immunoassay with polyclonal antibodies detected 0.1 µg of anchoveta egg proteins. Potential cross-reactions with proteins of coastal fish eggs were eliminated after the use of electrophoresis, Western blotting and ELISA. Protein detection time in euphausiid guts was 9 h (13°C) and egg protein decay rate was 0.0385 h-1. Geostatistical analysis identified a large area of egg abundance, and a smaller secondary egg aggregation within the area covered in the regular spawning biomass stock assessment survey in northern Chile (daily egg production method sampling grid). Eighteen percent of total captured euphausiids within the main aggregation of eggs provided positive reactions, indicating anchoveta egg proteins in their guts. Natural mortality rate calculated at the main spawning area was 0.868 d-1. The potential euphausiid consumption of eggs in this area varied from 3.9 × 10 12 to 4.4 × 10 12 eggs d-1. Euphausiid predation accounted for 24 to 27% of natural mortality. When added to mortality rate estimates resulting from anchoveta cannibalism in the Humboldt Current, our results suggest that half of the daily anchoveta egg production dies daily. Accordingly, these estimates challenge classical ideas of trophic webs that do not consider either young developmental stages or interspecific interaction schemes for control of dominant species in pelagic systems.
Uploads
Papers by Leonardo Castro