Seasonal pattern of zooplankton biomass in the Argentinian shelf off Southern Patagonia (45º - 55º S)

Sabatini, Marina Elena; Colombo, Gustavo Luis Alvarez

doi:10.3989/scimar.2001.65n121

Cited by 57 publications

(32 citation statements)

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“…6B, table 2). this decrease followed a rather uniform path, and is therefore not thought to be due (at least exclusively) to top-down regulation: the high biomass reported for copepods in this sector during autumn show a patchy distribution (Sabatini and Álvarez colombo, 2001). instead, inadequate conditions of temperature and food availability seem to be the most plausible explanation, since: (1) densities dropped below 1 ind.…”

Section: Methodsmentioning

confidence: 99%

“…10 6 km 2 ), extending from 36°S to 55°S and characterised by a strong seasonality. tidal forces and physico-chemical gradients generate well-defined fronts (acha et al, 2004;Bianchi et al, 2005), which concur with high levels of chlorophyll a (romero et al, 2006), large biomass of zooplankton (Sabatini and Álvarez colombo 2001;Sabatini and Martos, 2002) and fishery resources (Boschi, 1998). this shelf is dominated by the nutrient-enriched, saline, subantarctic waters of the Malvinas/Falkland current ( Fig.…”

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Morphological variability, spatial distribution and abundance of <em>Helicostomella</em> species (Ciliophora: Tintinnina) in relation to environmental factors (Argentine shelf; 40-55°S)

Santoferrara

Alder

2009

Sci. Mar.

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SuMMarY: For the first time a taxonomic and ecological study of species belonging to Helicostomella was performed over a mesoscale spatial distribution by examining ca. 3000 loricae collected in argentine shelf waters during the austral autumn. Microscopic and statistical analysis revealed that the general shape and the oral diameter remained practically constant in the whole area surveyed, despite a continuous length fluctuation of ca. 300 µm, which includes the entire range present in eight previously reported species. consequently, we consider that the genus may be represented only by H. subulata, whose strong fluctuations in length (mostly attributed to an increase in the collar length), density and biomass seem to respond to temperature, food availability and front-related processes. in Buenos aires coastal waters associated with a quasi permanent estuarine front (40-40.5°S), mixed conditions would favour moderate abundances of long loricae, whereas in northern (42.5-45.5°S) and southern (46-54.5°S) Patagonian waters, high (10 3 ind. L -1 ) and low (<5 ind. L -1 ) densities of short loricae seem to be a consequence of stratification and encystment, respectively. the non-occurrence of the species at 41-42°S, together with a three-fold reduction in length-related parameters between specimens from Buenos aires and Patagonian waters, suggests a disjunct distribution.Keywords: tintinnids, genus Helicostomella, lorica polymorphism, abundance, shelf dynamics, fronts, environmental factors.reSuMen: Variabilidad morfológica, distribución espacial y abundancia de las especies de Helicostomella (Ciliophora: Tintinnina) en relación con las condiciones ambientales (Mar Argentino; 40-55ºS). -Se realizó el primer estudio taxonómico y ecológico de mesoescala sobre las especies del género Helicostomella, examinando ca. 3000 lórigas colectadas en el Mar argentino durante el otoño austral. Los análisis microscópicos y estadísticos revelaron que la forma general de la lóriga y su diámetro oral permanecen prácticamente constantes en toda el área analizada, mientras que su longitud presenta una variación de ca. 300 µm, incluyendo todo el rango correspondiente a 8 especies previamente reportadas. en consecuencia, el género estaría representado por una única especie, H. subulata, cuyas variaciones en longitud (atribuidas principalmente a la longitud del cuello), densidad y biomasa responderían a la temperatura, disponibilidad y calidad del alimento y procesos frontales. en aguas costeras de Buenos aires asociadas a un frente estuarino casi permanente (40-40.5°S), las condiciones de mezcla favorecerían el desarrollo de lórigas largas en abundancias moderadas, mientras que en aguas del norte (42.5-45.5°S) y del Sur (46-54.5°S) de la Patagonia prevalecen lórigas cortas en densidades elevadas (10 3 ind. L -1 ) o muy bajas (<5 ind. L -1 ) como consecuencia de procesos de estratificación y enquistamiento, respectivamente. La no detección de la especie entre 41-42ºS, junto con la reducción en 3 veces de los parámetros relacionados con la...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Morphological variability, spatial distribution and abundance of <em>Helicostomella</em> species (Ciliophora: Tintinnina) in relation to environmental factors (Argentine shelf; 40-55°S)

Santoferrara

Alder

2009

Sci. Mar.

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“…The hyperiid amphipod Themisto gaudichaudii Guérin-Méneville, 1825 is a crucial food item for many of the fish and squid species distributed in the region (e.g. Padovani et al 2012) Jenyns, 1842)), it is another key species in the trophic dynamics of Austral Patagonia (Sabatini & Á lvarez-Colombo 2001).…”

Section: Patagonian Shelf Lmementioning

confidence: 99%

Impacts of climate variation and potential effects of climate change on South American seabirds – a review

Quillfeldt

Masello

2013

Marine Biology Research

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The coastal and oceanic waters around the South American coasts provide rich foraging grounds for breeding and wintering seabirds, but there is growing concern that climate change will provide additional pressures to the seabirds around South America. As in many other coastal ecosystems, seabirds around South America are already faced with threats to their breeding habitats such as human disturbance and introduced predators, and threats at sea such as persistent pollutants and pesticides and direct mortality risks due to fisheries and oil spills. The sensitivity of South American marine ecosystems to ocean climate anomalies is well known from the dramatic population collapses caused by El Niñ o Southern Oscillation (ENSO) events. However, longer-term climate change effects have been explored less often and few long-term data sets exist for South American seabirds. Seven Large Marine Ecosystems (LME) border South America. While all LMEs experienced warming during the last 50 years, their climate dynamics have differed in recent decades. Climate models suggest that potential climate change effects may be important, especially due to changes in ENSO intensity and frequency and associated changes in the ocean climate of Atlantic and Pacific marine ecosystems. In this review, we found that the best studied seabird communities are those of the Patagonian Shelf and the Humboldt Current, but overall, our knowledge on climate effects on South American seabirds is scarce.

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“…Mesozooplankton play a crucial role in the productivity and trophodynamics of the southern Patagonian shelf (SABATINI; ÁLVAREZ COLOMBO, 2001;CIANCIO et al, 2008;PADOVANI et al, 2012;SABATINI et al, 2012). At the end of summer and beginning of autumn the system becomes less productive.…”

Section: Introductionmentioning

confidence: 99%

FEEDING AND REPRODUCTIVE ACTIVITY OF THE COPEPODS Drepanopus forcipatus AND Calanus australis DURING LATE SUMMER ON THE SOUTHERN PATAGONIAN SHELF (ARGENTINA, 47°-55°S)

et al. 2014

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Drepanopus forcipatus and Calanus australis are key planktonic copepods on the southern Patagonian shelf. Their feeding and reproductive patterns and population status were investigated during late summer, when environmental conditions may be critical. The presence of food in the gut and food-pellet length were recorded in adult females and the most abundant copepodite stages. Diet composition was also studied in adult females. Female reproductive status was evaluated by gonad staging. Despite generally low feeding conditions and decreasing seasonal temperature, both copepods fed to some degree. The most numerous copepodites and adult females of both species showed similarly low feeding activity. About half of the adult females of the two species and C5s of C. australis contained food in their guts, but the proportion of fed C4-females of D. forcipatus was much lower. All copepods were generally feeding at low or intermediate levels. Gonad stage distribution and population structure showed low but still ongoing reproduction in both species. Gut content findings suggest a preference for smaller nanoplanktonic particles, especially dinoflagellates by D. forcipatus, and for autotrophic prey, particularly large diatoms by C. australis. The feeding and reproduction patterns of the two copepods were likely influenced by the distributions of potential food resources and temperature. RESUMODrepanopus forcipatus e Calanus australis são copépodos planctônicos relevantes na plataforma da Patagônia Austral. Seus padrões de alimentação, reprodução e status populacional foram investigados durante o fim do verão, quando as condições ambientais podem ser críticas. A presença de alimento no abdomen e o tamanho das pelotas alimentares foram registados em fêmeas adultas e nos estágios mais abundantes de copepodito. A composição da dieta também foi estudada em fêmeas adultas. O status reprodutivo das fêmeas foi avaliado através do estágio gonadal. De modo geral, apesar das baixas condições alimentares e diminuição sazonal da temperatura, ambos os copépodos se alimentaram. Os copepoditos mais numerosos e as fêmeas adultas de ambas espécies mostraram baixa atividade alimentar. Cerca de metade das fêmeas adultas das duas espécies e C5s de C. australis apresentaram alimento em seu intestino, porém a proporção de fêmeas D. forcipatus C4 alimentadas foi consideravelmente menor. De modo geral, todos os copépodos se alimentaram entre níveis baixo e intermediário. A distribuição do estágio gonadal e a estrutura populacional apresentaram reprodução baixa, mas contínua para ambas as espécies. Os alimentos encontrados no intestino sugerem uma preferência por partículas nanoplanctônicas, especialmente dinoflagelatos em D. forcipatus, e por presas autotróficas, particularmente grandes diatomáceas em C. australis. Os padrões de alimentação e reprodução dos dois copépodos foram provavelmente influenciados pela distribuição de recursos alimentares e temperatura.

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Seasonal pattern of zooplankton biomass in the Argentinian shelf off Southern Patagonia (45º - 55º S)

Cited by 57 publications

References 10 publications

Morphological variability, spatial distribution and abundance of <em>Helicostomella</em> species (Ciliophora: Tintinnina) in relation to environmental factors (Argentine shelf; 40-55°S)

Morphological variability, spatial distribution and abundance of <em>Helicostomella</em> species (Ciliophora: Tintinnina) in relation to environmental factors (Argentine shelf; 40-55°S)

Impacts of climate variation and potential effects of climate change on South American seabirds – a review

FEEDING AND REPRODUCTIVE ACTIVITY OF THE COPEPODS Drepanopus forcipatus AND Calanus australis DURING LATE SUMMER ON THE SOUTHERN PATAGONIAN SHELF (ARGENTINA, 47°-55°S)

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