Mariela Spinelli - Academia.edu (original) (raw)

Papers by Mariela Spinelli

Research Square (Research Square), Jun 21, 2024

Appendicularians are recognized as one of the most abundant mesozooplankton groups in numerous pe... more Appendicularians are recognized as one of the most abundant mesozooplankton groups in numerous pelagic environments and they play a crucial role in marine ecosystems as they bridge the gap between primary producers and higher trophic levels in the food webs. Zooplankton samples were collected during three spring oceanographic surveys conducted in 2014, 2015, and 2016, in the coastal zone (Staten Island) and oceanic zone (Namuncurá-Banco Burdwood Marine Protected Area). Our study focuses on a comparative analysis of species composition, density, biomass, and maturity stages of appendicularia between these oceanic and coastal regions, which are marked by distinct physical and biological attributes. Two species of appendicularians were found in the study area, Oikopleura fusiformis and Fritillaria borealis, the former being the dominant. Their distribution was different because F. borealis was mainly concentrated in the coastal zone while O. fusiformis was consistently recorded in both zones. Chlorophyll-a concentrations were found to be higher in the coastal zone than in the oceanic zone. These higher concentrations were accompanied by higher densities of O. fusiformis in that area. The surface current velocity seems to re ect the total phytoplankton biomass being higher in the oceanic zone. On the other hand, the temperature for the marine protected area was lower which could be related to the larger sizes of the appendicularians in that zone. Baseline data of the species in protected areas and surrounding areas is essential to contribute to the stakeholders and advise on future changes that translate into regional and global processes.

Ecología austral, Aug 1, 2016

The aim of this study is to analyze the annual zooplankton succession at a coastal station in Pat... more The aim of this study is to analyze the annual zooplankton succession at a coastal station in Patagonia (Argentina), with special emphasis on copepods and their potential preys, using solar radiation and temperature as environmental factors. The annual plankton cycle exhibited autumn/winter and spring/summer phases. During the autumn/winter phase, low temperature and radiation were correlated with higher diatom abundance and copepod diversity. This period was characterized by a dominant classical herbivorous food web in which the large copepod Calanoides carinatus dominated the community. On the contrary, during the spring/summer period, with high radiation and temperature levels, flagellates were the dominant food available for zooplankton and correlated with smaller species of copepods such as the harpacticoid Euterpina acutifrons. Also, intensive reproduction of the small copepods E. acutifrons and Paracalanus parvus occurred mainly in summer. On the other hand, high species diversity was found in winter when the ultraviolet radiation was low. The temporal pattern of the copepods observed in our study was explained by food availability and environmental factors (temperature and solar radiation), although other factors such as predator abundance may also be important in modulating the community. Our results show the importance of copepod abundance dynamics and highlights their key role in the pelagic food web in northern Patagonian coastal waters.

In aquatic ecosystems, global change encompasses human-induced variations in the upper layer of t... more In aquatic ecosystems, global change encompasses human-induced variations in the upper layer of the water column, where most of carbon fixation takes place. These changes include increments of exposure to solar UV radiation, mean temperature of surface seawater, ocean acidification and nutrient concentrations. These factors are well known to affect plankton ecosystems, although not all organisms are equally affected. In addition, many times these factors interact and the final results are not always additive or synergistic as expected. Finally, indirect effects (e.g., through trophic interactions) are often more pronounced than direct ones (e.g., survival or growth), which tend in some cases to mask overall and long-term expected ecological shifts in plankton communities.We review the main contributions in this field from the Atlantic coast of South America and discuss in a final section what have we learned and what is still unknown as global changes seems to be here to stay.Fil: B...

Plankton Ecology of the Southwestern Atlantic, 2018

Appendicularians generally comprise a significant fraction of mesozooplanktonic tunicates in mari... more Appendicularians generally comprise a significant fraction of mesozooplanktonic tunicates in marine environments. Their eggs, trunks, and houses are important food supply to large copepods, chaetognaths, ctenophores, and larvae and adults of engraulids. They are semelparous and hermaphrodites (except O. dioica) organisms, with a short and temperature-dependent life cycle. In this chapter, we discuss the seasonal dynamics of appendicularians, comparing life strategies of dominant species at distinct coastal environments of the Southwest Atlantic Ocean. O. dioica, O. fusiformis, Appendicularia sicula, and Fritillaria borealis are common coastal species in the southwestern Atlantic. Total abundance, biomass, and house production of O. dioica and A. sicula were higher during spring and summer. O. dioica and A. sicula bloomed during summer with temperatures between 17 and 20 °C. O. fusiformis appeared occasionally during summer and fall but in very low densities. Fritillaria borealis pre...

Journal of Marine Systems, 2020

Abstract The sub-Antarctic Namuncura Marine Protected Area at Burdwood Bank (NMPA/BB) is an area ... more Abstract The sub-Antarctic Namuncura Marine Protected Area at Burdwood Bank (NMPA/BB) is an area of favorable conditions for the development of planktonic organisms and the sustenance of numerous species of ecological importance. The current study aimed to evaluate the spatial distribution of the abundance, biomass, community structure, and functional diversity of the mesozooplankton from the NMPA/BB during spring 2014. We also assessed the potential of zooplankton as prey for upper trophic levels, in particular the larvae of the Fuegian sprat (Sprattus fuegensis), a key species in the food web of the NMPA/BB. A total of 26 zooplankton taxa were identified. Nauplii and copepods evidenced the highest abundances, with the latter representing the dominant group in terms of biomass. Copepods showed a strong eastward gradient in their abundance, biomass, and diversity. This spatial structure in the community composition seems to be modulated by a west-to-east decreasing trend in the size of available preys, with nano- and picoplankton playing a major role in the eastern part of the NMPA/BB. Such pattern would be, in turn, a consequence of productivity gradients along hydrographic features. The high abundance of nauplii and copepods suggests that spring is an appropriate time for their reproduction and, given their size structure, they represent an adequate food source for Fuegian sprat larvae. This would be enhanced by anticyclonic cells present in the NMPA/BB, which can gather and retain sprat larvae along with their zooplanktonic preys. The results of our study, which is the first comprehensive approach addressing the zooplanktonic indicators of the NMPA/BB, serve as a baseline for future ecosystem-based policies aiming to manage and protect the natural marine resources sheltered here.

Fisheries Research, 2018

Abstract We studied the abundance, size and growth rates of Engraulis anchoita larvae during the ... more Abstract We studied the abundance, size and growth rates of Engraulis anchoita larvae during the end of the species’ spawning season in relation to environmental variables. Two sampling transects, one in Peninsula Valdes (northern transect: NT) and the other in Isla Escondida (southern transect: ST), with four stations each, were established in late summer. Both locations are characterized by high concentrations of E. anchoita larvae in spring, strongly associated with the presence of frontal waters, at the beginning of the species’ spawning season. Zooplankton and ichthyoplankton were sampled, and temperature profiles and chlorophyll-a satellite images were analyzed for each sampling station. Zooplankton samples were divided in size fractions, and composition and abundances were estimated. Standard length (SL), ontogenetic stages, and abundance (including eggs) were estimated. Additionally, age and growth rates were determined by otolith analysis. Two different scenarios were observed in both transects. In the NT, a frontal structure was found, while at the ST, the water column was completely homogeneous. Total zooplankton abundance was maximum at frontal waters, with 22,195 ind. m−3, being the small size fraction (

Ciencias Marinas, 2016

Scientia Marina, 2011

We investigated the spatial distribution of the abundance, biomass and size of zooplankton (naupl... more We investigated the spatial distribution of the abundance, biomass and size of zooplankton (nauplii, calanoids, cyclopoids and appendicularians) in relation to the distribution of first-feeding larvae and eggs of Engraulis anchoita across the frontal system of Peninsula Valdés. Twelve samples of zooplankton and ichthyoplankton were taken with small Bongo (67 µm) and Pairovet (200 µm) nets during the spring of 2004 along two transects. The total abundance of zooplankton and the chlorophyll a concentration were higher in homogeneous waters, while total biomasses were higher in stratified waters. Temperature was negatively correlated with biological variables and was the main factor affecting the zooplankton distribution. In both transects, abundance peaks of first-feeding larvae were detected at coastal stations along with the smallest fraction of zooplankton (<500 µm), while the largest fraction was dominant at the external stations, coinciding with the highest egg abundance. The physical structure of this front generates different levels of food availability for first-feeding larvae. Calanoids (southern transect) and cyclopoids (northern transect) are predominant followed by nauplii and appendicularians. The biomass of zooplankton preys contributes to the carbon transfer to the upper trophic levels and is probably important for the survival and growth of anchovy larvae in this frontal system.

Brazilian Journal of Oceanography, 2013

Among tunicates, the small planktonic appendicularians generally comprise a significant fraction ... more Among tunicates, the small planktonic appendicularians generally comprise a significant fraction of the mesozooplankton in frontal systems. The summer 2011 distribution (vertical and spatial) of Oikopleura dioica was studied in terms of abundance, biomass, estimation of egg production and population structure in the different sectors of the El Rincón coastal front, in the light of thermal and salinity gradients. Peaks of abundance of Engraulis anchoita larvae were compared to O. dioica patterns. Samples were collected with plankton nets of 67 µm and 200 µm at two layers, below and above the thermocline depth. CTD data profiles were also recorded. During this campaign high salinity waters were predominant in the estuarine area. Conversely, a thermal stratification was found, being more marked at the external stations of the front where the highest densities and biomass of O. dioica coincided with the highest E. anchoita larvae densities. The size structure of O. dioica was also assoc...

Latin American Journal of Aquatic Research, 2014

Estuarine, Coastal and Shelf Science, 2009

... Historical hydrographic data reveal that the extension of the La Plata plume undergoes large ... more ... Historical hydrographic data reveal that the extension of the La Plata plume undergoes large amplitude seasonal fluctuations, being the plume dispersion highly dependent on the prevailing winds ( [Simionato et al., 2004] and [Piola et al., 2005] ). ...

Se estudio la estructura trofica del mesozooplancton con enfasis en Appendicularia y Copepoda en ... more Se estudio la estructura trofica del mesozooplancton con enfasis en Appendicularia y Copepoda en la region norpatagonica, poniendo atencion en su variacion espacial y estacional. Adicionalmente, se realizaron estudios con especies dominantes en esta zona para evaluar como factores ambientales pueden afectar las relaciones troficas en este ecosistema. Para ello, se analizo experimentalmente el efecto subletal de la radiacion ultravioleta en las tasas de alimentacion de copepodos. En todo el ciclo estacional dominaron los copepodos y la fraccion nanoplanctonica de fitoplancton. En verano se destaco una menor diversidad de especies, entre las que domino Euterpina acutifrons. Asimismo, se observo que la RUV inhibe la alimentacion de dicha especie y que en sus estadios larvales son capaces de realizar foto-reparacion. En cuanto a la variacion espacial, en el sistema frontal de Peninsula Valdes dominaron las menores tallas del mesozooplancton (‹ 500 μm) (copepodos calanoideos, ciclopoideo...

Marine Biology Research, 2015

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