Marcos Tatián

Bio: Marcos Tatián is an academic researcher from National University of Cordoba. The author has contributed to research in topics: Benthic zone & Cove. The author has an hindex of 17, co-authored 44 publications receiving 896 citations. Previous affiliations of Marcos Tatián include National Scientific and Technical Research Council.

Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem

Abstract: The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a “filter feeders–ascidian domination” to a “mixed assemblage” suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP.

Benthic faunal associations on soft substrates at Potter Cove, King George Island, Antarctica

Abstract: Associations of benthic invertebrates from Potter Cove (Antarctica) were defined from photo-transects. Density, percentage cover, species richness S′, diversity index H′, evenness index J′ and mean-size estimations were studied in relation to water depth down to 30 m. A clear bathymetric pattern was evident, with two different communities at 15 and 30 m, and a transition area between 20 and 25 m. At 15 m we observed a small number of taxa (nine in total), a high percentage of bare substratum (95%), and the dominant species were pennatulids and the bivalve Laternula elliptica. From 20 to 30 m the dominant species was the ascidian Molgula pedunculata and there was a slight increase in S′, H′ and J′, as well as in the mean size of individuals, especially in M. pedunculata, while the proportion of bare substratum showed a constant decrease with depth. Using multivariate analyses, three faunal assemblages related to depth were defined and a strong association of some species, mainly predators and opportunistic necrophages, with M. pedunculata was revealed. Ice impact (icebergs and anchor ice) seems to be the major regulating factor of benthic assemblages in shallow waters.

Namuncurá Marine Protected Area: an oceanic hot spot of benthic biodiversity at Burdwood Bank, Argentina

Abstract: The first open-sea (non-coastal) Marine Protected Area (MPA) in Argentina was created in 2013 (and named “Namuncura”), at Burdwood Bank, an undersea plateau located about 200 km south from Malvinas/Falkland Islands, SW Atlantic Ocean. This contribution represents the most recent and complete checklist of benthic organisms (mainly mega and macrofauna) that summarized 240 taxa collected at three sites in the mentioned area. The benthic richness here documented largely exceeds the values coming from other productive areas in Argentinean waters. Faunistic composition was different among the sites, although several species were shared. Bryozoans presented the highest richness compared to the other groups, followed by mollusks and sponges. These data represent valuable information and a very helpful starting point for incoming research, conservation efforts and management. It is essential to establish the spatial distribution of indicator taxa, like corals, sponges and bryozoans, to better attempt at the protection of benthic biodiversity in this rich Argentinean marine system. This is a key issue considering the notable extension of the MPA compared to other areas in Argentina, the bathymetric variations, particular oceanographic conditions and different fishing circumstances within the area.

Genetic differentiation between morphotypes in the Antarctic limpet Nacella concinna as revealed by inter-simple sequence repeat markers

Abstract: The limpet Nacella concinna (Strebel 1908) was the focus of numerous studies dealing with Antarctic benthos. One of the main characteristics of the species is the presence of two distinguishable morphotypes, one inhabiting the intertidal (during summer) and the other inhabiting the subtidal. For a long time these forms were considered as an expression of phenotypic plasticity, since previous studies did not found genetic differences between them. In the present work, we performed both a morphometric and a genetic differentiation analysis (using ISSR-PCR markers) of these two forms in three stations sampled at Potter Cove, South Shetland Islands. The results confirmed the morphological differences between intertidal and subtidal forms reported in other Antarctic localities. The genetic differences detected indicate that the two forms can be considered as genetically distinct populations maintaining low levels of gene flow. The degree of reproductive isolation of the ecotypes is discussed, as well as the possible origin of the divergence. The genetic differentiation observed can also have behavioral and physiological correlates, pointing out the importance of taking into account the potential differences in the response of both populations to different conditions in future studies in this species.

A new species

Abstract: We redescribe the only previously known species of Myrsidea from bulbuls, M. pycnonoti Eichler. Sixteen new species are described; they and their type hosts are: M. phillipsi ex Pycnonotus goiavier goiavier (Scopoli), M. gieferi ex P. goiavier suluensis Mearns, M. kulpai ex P. flavescens Blyth, M. finlaysoni ex P. finlaysoni Strickland, M. kathleenae ex P. cafer (L.), M. warwicki ex Ixos philippinus (J. R. Forster), M. mcclurei ex Microscelis amaurotis (Temminck), M. zeylanici ex P. zeylanicus (Gmelin), M. plumosi ex P. plumosus Blyth, M. eutiloti ex P. eutilotus (Jardine and Selby), M. adamsae ex P. urostictus (Salvadori), M. ochracei ex Criniger ochraceus F. Moore, M. borbonici ex Hypsipetes borbonicus (J. R. Forster), M. johnsoni ex P. atriceps (Temminck), M. palmai ex C. ochraceus, and M. claytoni ex P. eutilotus. A key is provided for the identification of these 17 species.

Intertidal landscapes: disturbance and the dynamics of pattern [Mytilus californianus, mussels]

Abstract: The mussel Mytilus californianus is a competitive dominant on wave—swept rocky intertidal shores. Mussel beds may exist as extensive monocultures; more often they are an everchanging mosaic of many species which inhabit wave—generated patches or gaps. This paper describes observations and experiments designed to measure the critical parameters of a model of patch birth and death, and to use the model to predict the spatial structure of mussel beds. Most measurements were made at Tatoosh Island, Washington, USA, from 1970—1979. Patch size ranged at birth from a single mussel to 38 m2; the distribution of patch sizes approximates the lognormal. Birth rates varied seasonally and regionally. At Tatoosh the rate of patch formation varied during six winters from 0.4—5.4% of the mussels removed per month. The disturbance regime during the summer and at two mainland sites was 5—10 times less. Annual disturbance patterns tended to be synchronous within 11 sites on one face of Tatoosh over a 10—yr interval, and over larger distances (16 km) along the coastline. The pattern was asynchronous, however, among four Tatoosh localities. Patch birth rate, and mean and maximum size at birth can be used as adequate indices of disturbance. Patch disappearance (death) occurs by three mechanisms. Very small patches disappear almost immediately due to a leaning response of the border mussels (0.2 cm/d). Intermediate—sized patches (<3.0 m2) are eventually obliterated by lateral movement of the peripheral mussels: estimates based on 94 experimental patches yield a mean shrinking rate of 0.05 cm/d from each of two principal dimensions. Depth of the adjacent mussel bed accounts for much of the local variation in closing rate. In very large patches, mussels must recruit as larvae from the plankton. Recovery begins at an average patch age of 26 mo; rate of space occupation, primarily due to individual growth, is 2.0—2.5%/mo. Winter birth rates suggest a mean turnover time (rotation period) for mussel beds varying from 8.1—34.7 yr, depending on the location. The minimal value is in close agreement with both observed and calculated minimal recovery times. Projections of total patch area, based on the model, are accurate to within 5% of the observed. Using a method for determining the age of patches, based on a growth curve of the barnacle Balanus cariosus, the model permits predictions of the age—size structure of the patch population. The model predicts with excellent resolution the distribution of patch area in relation to time since last disturbance. The most detailed models which include size structure within age categories are inconclusive due to small sample size. Predictions are food for large patches, the major determinants of environmental patterns, but cannot deal adequately with smaller patches because of stochastic effects. Colonization data are given in relation to patch age, size and intertidal position. We suggest that the reproductive season of certain long—lived, patch—dependent species is moulded by the disturbance regime. The necessary and vital connection between disturbance which generates spatial pattern and species richness in communities open to invasion is discussed.

A proposed unified framework for biological invasions.

Abstract: There has been a dramatic growth in research on biological invasions over the past 20 years, but a mature understanding of the field has been hampered because invasion biologists concerned with different taxa and different environments have largely adopted different model frameworks for the invasion process, resulting in a confusing range of concepts, terms and definitions. In this review, we propose a unified framework for biological invasions that reconciles and integrates the key features of the most commonly used invasion frameworks into a single conceptual model that can be applied to all human-mediated invasions. The unified framework combines previous stage-based and barrier models, and provides a terminology and categorisation for populations at different points in the invasion process.

Dynamics and Control

Abstract: 1. Control Methodology 2. Dynamical Systems 3. Applications to Social and Environmental Problems

On the direct impact of ice on marine benthic communities, a review

Abstract: Ice has a significant impact on the polar and sub-polar benthos, but relationships between corresponding physical and biological processes are not yet sufficiently understood. Sea ice contributes to a vertical zonation in shallow waters, which also experience other important disturbances. Due to the length of the non-glaciated coastline, sea ice is of greater relevance in the north than in the south. Scouring by icebergs and ridged sea ice causes an increased diversity when different recolonisation stages coexist. Frequently scoured areas do not recover, especially in the Antarctic, due to slow growth rates of the fauna. Iceberg grounding in the Arctic is mainly restricted to the western Eurasian and northeastern American shelf, including Greenland. Around Antarctica, scouring is more evenly distributed. Glacier termini prevent sessile animals from settling in their proximity where only few motile species occur.