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  1. Article ; Online: Impact of Increased Nutrients and Lowered pH on Photosynthesis and Growth of Three Marine Phytoplankton Communities From the Coastal South West Atlantic (Patagonia, Argentina)

    Takako Masuda / Ondřej Prášil / Virginia E. Villafañe / Macarena S. Valiñas / Keisuke Inomura / E. Walter Helbling

    Frontiers in Marine Science, Vol

    2021  Volume 8

    Abstract: Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters ...

    Abstract Effect of global change variables on the structure and photosynthesis of phytoplankton communities was evaluated in three different sites of the Patagonian coast of Argentina: enclosed bay (Puerto Madryn, PM), estuarine (Playa Unión, PU), and open waters (Isla Escondida, IE). We exposed samples to two contrasting scenarios: Present (nutrients at in situ levels) vs. Future (with lowered pH and higher nutrients inputs), and determined growth and photosynthetic responses after 2 days of acclimation. Under the Future condition phytoplankton growth was higher in the estuarine site compared to those in PM and IE. This effect was the most pronounced on large diatoms. While the increase of photosynthetic activity was not always observed in the Future scenario, the lower photosynthetic electron requirement for carbon fixation (Φe,C = ETR/PmB) in this scenario compared to the Present, suggests a more effective energy utilization. Long-term experiments were also conducted to assess the responses along a 4 days acclimation period in PU. Diatoms benefited from the Future conditions and had significantly higher growth rates than in the Present. In addition, Φe,C was lower after the acclimation period in the Future scenario, compared to the Present. Our results suggest that the availability, frequency and amount of nutrients play a key role when evaluating the effects of global change on natural phytoplankton communities. The observed changes in diatom growth under the Future scenario in PU and IE and photosynthesis may have implications in the local trophodynamics by bottom up control.
    Keywords global change ; plankton community structure ; carbon incorporation ; oxygen production ; PSII photochemistry ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Subject code 333
    Language English
    Publishing date 2021-02-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Effects of two estuarine intertidal polychaetes on infaunal assemblages and organic matter under contrasting crab bioturbation activity

    Alvarez, M. Fernanda / Eugenia Fanjul / Florencia Botto / M. Cielo Bazterrica / Macarena S. Valiñas / Mariana S. Addino / Oscar O. Iribarne

    Journal of sea research. 2018 Sept., v. 139

    2018  

    Abstract: Polychaetes and burrowing crabs are widely distributed in intertidal soft bottom environments, playing an important role in structuring infaunal assemblages through trophic and non-trophic interactions such as bioturbation. In southwestern Atlantic (SWA; ...

    Abstract Polychaetes and burrowing crabs are widely distributed in intertidal soft bottom environments, playing an important role in structuring infaunal assemblages through trophic and non-trophic interactions such as bioturbation. In southwestern Atlantic (SWA; 37°40′S, 57°23′W) intertidal mudflats, the polychaetes Laeonereis acuta and Neanthes succinea coexist with the burrowing crab Neohelice (Chasmagnathus) granulata. N. granulata and L. acuta strongly modify the sediment characteristics at different spatial scales, changing the infaunal assemblages and probably affecting feeding mode of N. succinea, which could prey upon L. acuta. Here, we experimentally evaluated the effects of constant densities of L. acuta and N. succinea on the benthic species assemblages and sediment organic matter (OM) content in two contrasting scenarios of crab bioturbation: inside and outside crab beds. We found that (1) both polychaetes did not affect the mean density of other macrofaunal organisms neither the meiofauna in general, but L. acuta modifies the abundance of specific groups such as foraminiferans; (2) polychaetes produced changes in meiofaunal spatial distribution probably by adding habitat heterogeneity; and (3) no evidence of predation of N. succinea on L. acuta were observed. Additionally, the variable effects of polychaetes on chlorophyll and OM content showed that they were species-specific and also modified by crab bioturbation. Moreover, effects of crab bioturbation on primary producers, quality and content of OM, and on some macro and meiofaunal organisms were found. Our results suggest that the effects of L. acuta and N. succinea on benthic species and OM content are mostly species-specific and, with regard to food sources (OM content and microphytobenthic biomass), strongly modified by larger scale crab bioturbation.
    Keywords Alitta succinea ; benthic organisms ; biomass ; bioturbation ; chlorophyll ; crabs ; estuaries ; fauna ; habitats ; littoral zone ; organic matter ; predation ; sediments
    Language English
    Dates of publication 2018-09
    Size p. 33-40.
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 1385-1101
    DOI 10.1016/j.seares.2018.06.008
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Effect of Spartina alterniflora Loisel, 1807 on growth of the stout razor clam Tagelus plebeius (Lightfoot, 1786) in a SW Atlantic estuary

    Addino, Mariana S / Betina J. Lomovasky / Diana I. Montemayor / M. Fernanda Alvarez / Macarena S. Valiñas / Mauricio Escapa / Oscar Iribarne

    Journal of experimental marine biology and ecology. 2015 Feb., v. 463

    2015  

    Abstract: Aquatic organisms that produce epibenthic structures such as saltmarsh plants play key roles in habitat functioning through their ecosystem engineering effects. Intertidal Spartina species are well known for modifying tidal hydrodynamic and sediment ... ...

    Abstract Aquatic organisms that produce epibenthic structures such as saltmarsh plants play key roles in habitat functioning through their ecosystem engineering effects. Intertidal Spartina species are well known for modifying tidal hydrodynamic and sediment processes, affecting cohabiting infaunal organisms. The stout razor clam Tagelus plebeius is an infaunal filter-feeding species that inhabits a broad range of mudflats (MF) and Spartina saltmarshes (SM) along the American Atlantic coast. Through descriptive and experimental approaches conducted at the Bahía Blanca estuary (Argentina, 38°47′S, 62° 20′W), we evaluated ecosystem engineer effects of Spartina alterniflora (due to changes in sediment and water characteristics) on somatic and shell growth of T. plebeius. Comparison of bulk sediment parameters indicated that the sediment is more easily eroded in the SM than in the MF, but softer in the latest. In addition, food supply for clams (i.e., total particulate organic matter) was higher in the MF although food quality (i.e., percentage of organic matter in the water column) was in general higher in SM. Shell growth was higher but clam condition index (CI) was lower in the MF, and the opposite pattern was found in the SM. These results represent an uncoupling between shell and somatic growth with a positive effect of S. alterniflora on the CI of clams. Nevertheless, results of field experiments manipulating stems and roots of plants separately suggested that the effect of Spartina on clam's CI was not due to the structural changes generated by plant presence itself, although a better food quality in the SM may be related to the larger clams CI.
    Keywords aquatic organisms ; clams ; coasts ; ecosystem engineering ; ecosystem engineers ; estuaries ; field experimentation ; food availability ; food quality ; habitats ; hydrodynamics ; littoral zone ; particulate organic matter ; roots ; salt marsh plants ; salt marshes ; sediments ; Spartina alterniflora ; stems ; Veneroida ; Argentina
    Language English
    Dates of publication 2015-02
    Size p. 135-142.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 410283-6
    ISSN 0022-0981
    ISSN 0022-0981
    DOI 10.1016/j.jembe.2014.11.011
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 74/703: Show issues

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  4. Article ; Online: Combined impact of ultraviolet radiation and increased nutrients supply

    Macarena S. Valiñas / Paula eBermejo / Lara eGalbán / Luciana eLaborda / Donat P. Häder / Virginia E. Villafañe / E. Walter eHelbling

    Frontiers in Environmental Science, Vol

    A test of the potential anthropogenic impacts on the benthic amphipod Amphitoe valida from Patagonian waters (Argentina)

    2014  Volume 2

    Abstract: Experiments were conducted during the Austral Summer of 2014 to determine the effects of increased nutrient input and ultraviolet radiation (UVR) on the food consumption rate (FCR) and food preference in the amphipod Amphitoe valida. We collected ... ...

    Abstract Experiments were conducted during the Austral Summer of 2014 to determine the effects of increased nutrient input and ultraviolet radiation (UVR) on the food consumption rate (FCR) and food preference in the amphipod Amphitoe valida. We collected specimens from the Patagonian coast (Argentina), from beaches close (Barrancas Blancas; BB) and further away (Cangrejales; C) from the Chubut River, which constitutes the potential source of eutrophication. Organisms were exposed to different radiation regimes (full radiation vs. PAR only) and fed with different macroalgae diets (i.e., from different geographical location and with different quality in terms on nutrient content). Males collected from C showed food compensation, consuming more food under low-nutrient diets, while no compensation was observed in males from BB. Regardless of their origin, UVR decreased the FCR when males where fed on ambient nutrient diets, but not when males fed on high-quality diets indicating that in the former case, individuals were in worse physiological conditions to cope with UVR; food quality, however, significantly counteracted the deleterious effects of UVR on FCR. Females collected from the two beaches showed similar FCR under high-nutrient diet and had no food compensation when fed in low-nutrient diets. Females were more vulnerable to UVR, since their FCR were lower when exposed to UV radiation independent of the diet. Our results show that under anthropogenic eutrophication and high solar UVR levels an increase in the nutrient input could favor only males of A. valida, by reducing the negative effects of UVR on their FCR. Nevertheless, these nutrient inputs might cause additional problems like anoxia, as a result of an unusual macroalgal growth, thus affecting amphipod’s survival.
    Keywords global change ; Nutrients ; ultraviolet radiation ; Patagonia ; amphipods ; Environmental sciences ; GE1-350
    Subject code 590
    Language English
    Publishing date 2014-08-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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