BENTHIC DIVERSITY OF THE RÍO DE LA PLATA ESTUARY AND

ADJACENT MARINE WATERS

DIEGO A. GIBERTO

SUPERVISOR: CLAUDIA S. BREMEC PNUD Project/Gef RLA/99/G31 2003

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¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ BENTHIC DIVERSITY OF THE RÍO DE LA PLATA ESTUARY AND ADJACENT MARINE WATERS

Report ______

AUTHOR: DIEGO A. GIBERTO SUPERVISOR: CLAUDIA S. BREMEC ______

Summary

The main objectives of this report are to analyze the infralitoral benthic assemblages of the Río de la Plata estuary and adjacent marine zones, and establish broad patterns of species diversity throughout the study area. Species richness was utilized as a measure of diversity. The report was divided in two major approaches: the analysis of an historical background and the EH-09-99 survey. The taxonomical groups that contributed with the major number of species were the mollusks, crustaceans, polychaetes, echinoderms and coelenterates. A classical gradient of increasing species richness from estuarine to marine waters was found. Also, few species were found inhabiting both estuarine and marine waters. The species richness values were high at the continental shelf and the coastal marine environments. The highest number of species was recorded in mussel beds and coarse-sandy bottoms marine assemblages. The irregular pattern of species richness found in marine waters could be due to the presence of different heterogeneous bottom types all over the study area. It is concluded that the available information about benthic communities inhabiting the study area is scarce. In addition, a large portion of the studies were developed mainly on the marine zones < 50 m, while the estuarine zones and the marine zones > 50 m are underestimated. Basic information related with diversity like abundance, biomass, dispersal and temporal variations of macrobenthic species are needed.

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Index

I. Introduction…………………………………………………………………………..1

II. Methodology……………………………………………………………………...... 1

III. Results………………………………………………………………………………..3

IV. Concluding remarks……………………………………………………………...... 5

V. Literature cited……………………………………………………………………….7

VI. Tables……………………………………………………………………………….10

VII. Figures………………………………………………………………………………13

VIII. Appendix…………………………………………………………………………….22

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Introduction

Species diversity is a community attribute influenced by historical events and geographical phenomena; it is also an emergent consequence of local ecosystems-level processes. Changes in diversity reflect changes in ecosystem processes, such as productivity, pathways of energy and material flow, disturbance regime, abiotic stress, and biological interactions (Brown et al., 2001). Species richness, or the number of species, is currently the most widely used diversity measure, together with indexes that also consider the relative species abundance in the community like H’ (Shannon Wiener) o J’ (Pielou’s evenness) (Stirling & Wilsey, 2001). The main objectives of this work are to analyze the infralitoral benthic assemblages of the Río de la Plata estuary and adjacent marine zones, and establish broad patterns of species diversity throughout the study area.

Methodology

Despite the fact that diversity can change without any change in species richness (species richness is not generally the common cause of variation in either H’ o J’) (Stirling & Wilsey, 2001), the species richness was utilized as a measure of diversity in this study, following Gray (2000) who suggested the species richness as a basic estimation of diversity. At the most elementary level, species richness is the total number of species in a given area (Gray, 2000). Following Gray (2000), we calculated for each defined sector the point species richness SRP (number of species in a single sampling unit from a given area) and the sample species richness. The sample species richness can be calculated as the total number of species, SRS, based on a given number of sampling units. Samples species richness is equivalent to the diversity of samples within a habitat, usually called alpha diversity. For the entire study area the SRL or large area species richness was calculated. This is defined as the species richness of a large area which includes a variety of habitats and assemblages. 2

The report was divided in two major approaches, as follows:

Historical background: the prevalent information available in the bibliography of benthic assemblages of the Río de la Plata estuary and adjacent marine zones is the number of species. These studies were done with highly variable sampling methodologies that make unfeasible the building of a detailed species inventory with standardized abundance data (see table I). Systematic publications that focused only on one taxonomical group (see for example Bernasconi & D’Agostino, 1977; Tablado & Maytía, 1988; Boschi et al., 1990) and other ecological ones that do not provide information on the presence of species in every sampling station (Bastida et al., 1989, 1992; Bremec et al. 1998; Bremec and Lasta, 2002; Roux et al., 1993) were not used in the analysis, because it would introduce a bias throughout the species richness pattern of certain taxa at a given area. The study area was divided in four main sectors, as follows: 1) an estuarine zone (mixohaline waters, is equivalent to the sector 1 of EH-09-01 survey), 2) a marine zone in front of the Argentine coast (depth < 50 m, is equivalent to sector 2 of EH-09-01 survey), 3) a marine zone in front of the Uruguayan coast (depth < 50 m, is equivalent to sector 2 of EH-09-01 survey) , and 4) a marine zone with depths > 50 m (is equivalent to sectors 3 and 4 of the EH-09-01 survey) (Fig. 1). These division was made considering oceanographic (salinity, bathymetry) and bottom (sediment composition) features (Urien, 1972; Guerrero et al., 1997, Mianzan et al., 2001), which probably influence the spatial distribution of benthic assemblages. Also, each publication was assigned to the following benthic assemblages: mussel beds (N1, N5 and N7, dominance of Mytilus edulis platensis), scallops beds (N8, dominance of Zygochlamys patagonica), coarse-sandy bottoms (N4, N6, N9 and N10), muddy-bottoms (N6 and N9) and Uruguayan rocky-sandy beaches (N2 and N3) (Table II and Fig. 1).

EH-09-01 survey: The study area was divided in four main sectors, as follows: 1) an estuarine environment (< 25, mixohaline waters), 2) a coastal environment (> 25, depths < 50 m), 3) a continental shelf environment (depths 50-200 m) and 4) a 3 shelf-break environment (depths > 200 m) (Table II and Fig. 2). This division was made largely following Acha and Lo Nostro (2002).

Results

Historical background

A total of 420 species (SRL) and 14 taxa were recorded in the study area (see list in Appendix 1). Marine waters were characterized by higher number of species than estuarine waters (373 vs. 47 respectively). SRP from the sampling stations of the estuarine waters ranged between 1 and 20, while stations of the marine waters ranged between 1 and 65 (Fig. 3). The taxonomical groups that contributed with the major number of species were the Mollusks (153 species), Crustaceans (88 species), Polychaetes (81 species), Echinoderms (29 species) and Cnidarians (27 species) (Appendix 1).

The estuarine zone was characterized by 6 taxa (SRS= 47), with mollusks, crustaceans and polychaetes contributing with more than 90 % of specific richness (Table III and Fig. 4). The marine waters < 50 m reached the highest number of species and taxa (SRS= 273 and SRS= 138 at Uruguay and Argentine respectively), while deeper stations (> 50 m) displayed the lowest values of specific richness in marine waters (SRS= 51) (Table III and Fig. 4). The contribution of all different taxa recorded at each zone is indicated in Fig. 4. The marine zone > 50 m presented the higher percentages of “exclusive species” (species that were only recorded in the defined area) (84.31%), followed by the marine Uruguayan zone (73.26%) and the marine Argentine zone (54.35%). The lowest value was recorded in the estuarine zone (34.04%). Only ten species were recorded in estuarine and marine waters: Angulus gibber, Corbula patagonica, Mactra isabelleana, Nucula puelcha, Pitaria rostrata, Ancinus depressus, Artemesia longinaris, Pagurus exilis, Pinnixa brevipollex and Encope emarginata.

Benthic assemblages that reached the highest values of SRS were those inhabiting mussel beds (SRS= 213) and coarse-sandy bottoms (SRS= 184) (Table IV). 4

The scallop beds presented the higher values of “exclusive species” (81.58%), followed by the coarse-sandy bottoms (77.17%), mussel beds (76.53%), Uruguayan beaches (53.57%) and the muddy bottoms (34.29%) assemblages. Only two species were recorded at three of the defined assemblages: Mytilus edulis platensis and Pseudoechinus magellanicus (see Appendix 1).

EH-09-01 survey

A total of 145 species (SRL) and 12 taxa were recorded in the study area (see list in Appendix 1 and 2). Mollusks were the dominant group, with 43 species, followed by polychaetes (35 species), crustaceans (32 species) and echinoderms (14 species) (Fig. 5).

The highest value of SRS (sample species richness) was found in the continental shelf environment, while the estuarine environment displayed the lowest SRS value (Fig. 6). The contribution of the different taxa recorded at each environment is indicated in Fig. 4. Mollusks and polychaetes reached the highest richness at the continental shelf environment, while crustaceans richness was highest in the coastal environment (Fig. 7). On the other hand, echinoderms, coelenterates and other less important groups displayed low and similar richness values in all the environments of marine waters analyzed (Fig. 7). The continental shelf environment presented the higher percentages of “exclusive species” (species that were recorded only in the defined area) (51.09%), followed by the coastal (46.25%) and the estuarine (41.67%) environments. The lowest value was recorded in the shelf-break environment (26.09%). Only 5 species were found both in estuarine and coastal waters: Artemesia longinaris, Buccinanops lamarckii, Corbula patagonica, Pagurus criniticornis, and Leptocuma sp.

Low SRP values were found at the stations of the estuarine environment (Fig. 8).

On the other hand, stations of marine waters displayed unevenly SRP values, ranging from stations with one (i. e. station 805, with sandy bottoms and only one species, the sand dollar Encope emarginata) to 39 species (station 802). The relation between species richness and salinity and depth is displayed in Fig. 9. 5

Opposite to species richness, both environmental variables displayed a constant pattern from marine to estuarine waters, lacking of a strong relationship with the curve of SRP (Significant correlation only between species and salinity at p < 0.05, r = 0.47).

Concluding remarks

1) The benthic assemblages of the estuarine environment were characterized by low diversity values, while adjacent marine zones reached the highest values. This pattern is in coincidence with the early predictions for mixohaline waters of Remane and Schlieper (1971). The species richness values were high at the continental shelf and the coastal environments. However, species richness in the shelf-break environment was lower than the other marine environments. 2) Higher number of species was recorded at mussel beds and coarse-sandy bottoms assemblages. These are characterized by a higher structural complexity than the homogenous muddy bottoms; this heterogeneity is associated with higher number of possible niches that allows the coexistence of an elevated number of species. Also, a general pattern of “widespread to exclusive” species from the estuarine to the marine zone respectively were found. This was also reflected in the composition of the muddy bottoms (mainly widespread species) to the scallop beds (mainly exclusive species). 3) Few species were found inhabiting both estuarine and marine waters (less than 3% of 420 species recorded in the historical analysis and less than 5% of 145 species in the EH-09-01 survey). 4) The irregular pattern of species richness found in marine waters could be due to the presence of different heterogeneous bottom types all over the study area. Except for the channel zone, the marine environment is characterized by sandy bottoms, with a transitional zone, and a coarse sedimentary texture in the inner shelf (Urien, 1972). The influence of bottom type had an important effect in the spatial distribution and diversity of the fauna (see Platell and Potter, 1996; Brown et al., 2001). 6

5) Available information about benthic communities inhabiting the study area is scarce. In addition, a large portion of the studies were developed mainly on the marine zones < 50 m, while the estuarine zones and the marine zones > 50 m are underestimated. Basic information related with diversity like abundance, biomass, dispersal, and temporal variations of macrobenthic species are needed.

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Literature cited

Acha, M. & Lo Nostro, S. 2002. Biology of the populations. Technical report. PNUD Proyect/GEF RLA/99/G31: 52 pp. Bernasconi, I & D’Agostino, M. M. 1977. Ofiuroideos del Mar Epicontinental Argentino. Revista del Museo Argentino de Ciencias Naturales”Bernardino Rivadavia” e Instituto Nacional de Investigación de las Ciencias Naturales 5(5): 65-125. Bastida, R., Roux, A. & Bremec, C. 1998. Investigaciones sobre las comunidades bentónicas en la zona común de pesca Argentino-Uruguaya. Frente Marítimo 5:115-129. Bastida, R., Roux, A. & Martínez, D. E. 1992. Benthic communities of the Argentine continental shelf. Oceanologica Acta 15: 687-698. Boschi, E. E., Fischbach, C. E., & Iorio, M. I. (1992). Catálogo ilustrado de los crustáceos estomatópodos y decápodos marinos de Argentina. Frente Marítimo 10: 7-94. Brankevich, G., Roux, A. & Bastida, R. Relevamiento de un banco de pesca del besugo (Sparus pagrus) en la plataforma bonaerense. Características fisiográficas generales y aspectos ecológicos preliminares. Frente Marítimo 7(A); 75-86. Bremec, C. & Roux, A. 1997. Resultados del análisis de una campaña de investigación pesquera, sobre comunidades bentónicas asociadas a bancos de mejillón (Mytilus edulis platensesis D’Orb.) en costas de Buenos Aires, Argentina. Revista de Investigación y Desarrollo Pesquero 11: 153-166. Bremec, C. S. & Lasta, M. L. 2002. Epibenthic assemblage associated with scallop (Zygochlamys patagonica) beds in the Argentinean shelf. Bulletin of Marine Science 70: 89-102. Bremec, C., Lasta, M. L., Lucifora, L. & Valero, J. 1998. Análisis de la captura incidental asociada a la pesquería de viera patagónica (Zygochlamys patagonica King and Broderip, 1832). INIDEP Informe Técnico N° 22:1-18 pp. 8

Bremec, C. S., Schejter, L. & Giberto, D. A. 2001. Vieira patagónica. Unidad norte de manejo-CTMFM. Evaluación de biomasa fauna acompañante año 2001. INIDEP n° 14, 12 pp. Brown, J. H.; Morgan Ernest, S. K.; Parody, J. M. & Haskell, and J. P. 2001. Regulation of diversity: maintenance of species richness in changing environments. Oecologia 126: 321-332. Demicheli, M. A. 1984. Estudios exploratorios del infralitoral de las playas arenosas uruguayas. I. Playa Portezuelo. . Comunicaciones de la Sociedad Malacológica del Uruguay 6(47): 235-249. Giberto, D. A. 2001. Fondos de alimentación de la corvina rubia (Micropogonias furnieri) en el estuario del Río de la Plata, Argentina-Uruguay. Facultad de Ciencias Exactas y Naturales. Universidad Nacional de Mar del Plata. 83 pp. Gray, J. S. 2000. The measurement of marine species diversity, with an application to the benthic fauna of the Norwegian continental shelf. Journal of Experimental Marine Biology and Ecology 250: 23-49. Guerrero, R. A.; Acha, E. M.; Framiñan, M. B. and Lasta, C. A. 1997. Physical oceanography of the Río de la Plata Estuary, Argentina. Cont. Shelf Res. 17 (7): 727-742. Hill, J. S. 2000. The measurement of marine species diversity, with an application to the benthic fauna of the Norwegian continental shelf. Journal of Experimental Marine Biology and Ecology 250: 23-49. Juanicó, M. & Rodriguez Moyano, M. 1975. Composición faunística de la comunidad de Mytilus edulis platensesis D’Orbigny, 1846 ubicada a unas 55 millas al SE de la Paloma. Comunicaciones de la Sociedad Malacológica del Uruguay 4(29): 113-116. Mianzan, H., C. Lasta, E. Acha, R. Guerrero, G. Macchi, and C. Bremec. 2001. The Río de la Plata estuary, Argentina-Uruguay, p. 185-204. In Seeliger U., L. D. de Lacerda and B. Kjerve (eds.), Coastal Marine Ecosystems of Latin America. Springer-Verlag, Berlin. 9

Obenat, S., Ferrero, L. & Spivak, E. 2001. Macrofauna associated with Phyllochaetopterus socialis aggregations in the southwestern Atlantic. Vie et Milieu 51(3): 131-139. Plattell, M. and I. Potter. 1996. Influence of water depth, season, habitat and estuary location on the macrobenthic fauna of a seasonally closed estuary. Journal of the Marine Biological Association of the United Kingdom 76: 1-21. Remane, A. and C. Schlieper, 1971. Biology of Brackish Water. John Wiley and Sons, New York, 372 pp. Riestra, G., Giménez, J. L. & Scarabino, V. 1992. Análisis de la comunidad macrobentónica infralitoral de fondo rocoso en Isla Gorriti e Isla de los Lobos (Maldonado, Uruguay). Frente Marítimo 11(A): 123-127. Roux, A. & Bremec, C. 1996. Comunidades bentónicas relevadas en las transecciones realizadas frente al Río de la Plata (35°15’S), Mar del Plata (38°10’S) y Península Valdes (42°35’S), Argentina. INIDEP Informe Técnico 11: 1-13. Roux, A., Bastida, R., & Bremec, C. 1993. Comunidades bentónicas de la plataforma continental argentina. Campañas transección BIP “Oca Balda” 1987/88/89. Bolm. Inst. oceanogr. S. Paulo 41: 81-94. Scarabino, V., Maytía, S. & Cachés, M. 1975. Carta binómico del departamento de Montevideo. I. Niveles superiors del sistema litoral. Comunicaciones de la Sociedad Malacológica del Uruguay 4(29): 117-130. Stirling, G. and Wilsey, B. 2001. Empirical relationships between species richness, evenness, and proportional diversity. The American Naturalist 158 (3): 286- 299. Tablado, A & Maytia, S. 1988. Presencia de Perissasterias polyacantha H. L.

Clark, 1923 (Echinodermata, Asteroidea) en el Océano Atlántico

Sudoccidental. Comunicaciones Zoológicas del Museo de Historia Natural de

Montevideo 12(169): 1-11.

Urien, C. M. 1972. Río de la plata estuary environments. The Geological Society of America, Memoir, 133: 213-233. 10

TABLES

Table I. Bibliographic sources used in the historical analysis.

Number Authors- Year Information Sampling Area Type methods Juanicó & Rodriguez Commercial Marine N1 Presence data Moyano, 1975 dredges waters Scarabino et al., Subtidal N2 Presence data Visual Census 1975 beaches Subtidal N3 Demicheli, 1984 Presence data Scuba beaches Brankevich et al., Abundance Marine N4 Dredge 1990 data* waters Abundance Subtidal N5 Riestra et al., 1992 Scuba data beaches Marine and Roux & Bremec, N6 Presence data Dredge estuarine 1996 waters Bremec & Roux, Abundance Marine N7 Dredge 1997 data waters Abundance & Marine N8 Bremec et al., 2001 Dredge biomass data waters Marine and Abundance & N9 Giberto, 2001 Dredge estuarine biomass data waters Marine N10 Obenat et al., 2001 Presence data Trawl waters * Indicated only for mollusks.

Table II. Sampling design of the EH-09-01 survey. Zone Sampling stations Bottom type Sampling gear Estuarine 4 mud grab Coastal 9 sand, shell debris dredge Continental Shelf 5 sand, shell debris dredge Shelf-break 2 sand, shell debris dredge

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Table III. Taxonomic groups (SRL= 420) at the study area. Contribution to each area is indicated in percentage of sample richness (SRS).

Taxa Estuarine Marine U < 50 m Marine A < 50 m Marine > 50 m

Annelida - 0.37 - - (Olygochaeta)

Annelida 21.28 22.71 8.70 11.76 (Polychaeta)

Brachiopoda - - - 3.92

Briozoa - 2.93 3.62 -

Chaelicerata - 0.73 - -

Cnidaria 4.26 7.33 2.90 5.88

Crustacea 31.91 24.54 15.22 11.76

Echinodermata 2.13 5.13 5.07 31.37

Mollusca 38.30 31.50 60.14 19.61

Nemertea - 1.10 - -

Platelminta - 0.37 - -

Porifera 2.13 2.20 2.90 5.88

Sipunculida - 0.37 - -

Tunicata - 0.73 1.45 9.80

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Table IV. SRS (Sample species richness) recorded at each benthic assemblage defined at the study area.

Taxa Mussel Muddy Coarse- Uruguayan rocky Scallops beds bottoms sandy and sandy beds bottoms beaches

Annelida - - 1 - - (Olygochaeta) Annelida 17 9 55 6 2 (Polychaeta) Brachiopoda - - - - 2 Briozoa 7 - 6 - - Chaelicerata 1 - 1 - - Cnidaria 9 2 13 - 3 Crustacea 36 8 47 13 4 Echinodermata 13 1 14 - 16 Mollusca 120 14 37 8 5 Nemertina 1 - 1 1 - Platelminta 1 - 0 - - Porifera 6 1 4 - 3 Sipunculida - - 1 - - Tunicata 2 - 4 - 3

SRS = 213 35 184 28 38

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FIGURES

Fig. 1. Benthic sampling locations analyzed in the study area. Estuarine (1), marine Argentinean < 50m (2), marine Uruguayan < 50m (3) and marine > 50m (4) zones are also indicated. Benthic assemblages as follows (see text for details): Coarse-sandy bottoms. Mussel beds. Uruguayan rocky-sandy beaches. Scallops beds. Muddy bottoms. 14

Fig. 2. The Río de la Plata estuary and adjacent marine waters, with location of sampling sites (n= 21) (•) and isobaths (m) (EH-09-01). 1 = estuarine environment (< 25, mixohaline waters), 2 = coastal environment (> 25, depths < 50 m), 3 = continental shelf environment (depths 50-200 m), 4 = shelf-break environment (depths > 200 m).

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Fig. 3. Point species richness (SRP) recorded at the study area.

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Fig. 4. Contribution in number of species (in brackets) to the sample species richness (n= SRS) at each defined area.

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50

s

e

i

pec

s

25

of

°

N

0

a a a a a c e ta t ta ra t da s c a at a fe a dae a m c oc toda ri rd i llu haeta t a o goni ul o c s uni m P ho o M ly u lenter T topr e n o e c N oc c P Cr noder o E y ipunc hi C hal P S c p E e C

Figure 5. Benthic species richness (number of species) of taxonomic groups in the Río de la Plata estuary and adjacent marine waters (EH-09-01).

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100

92

80

80

s

e

i

60

ec

p

s

of

40

° N

23

20

12

0 Estuarine Coastal Continental Shelf Shelf-break

Figure 6. Sample species richness (SRS) at each established zone of the Río de la Plata estuary and adjacent marine waters (EH-09-01).

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30 Mollusca

Polychaeta

25 Crustacea Echinodermata Coelenterata 20 Others

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10

5

0 Estuarine Coastal Continental Shelf Shelf-break

Figure 7. Sample species richness (SRS) of major taxa at each established zone of the study area (EH-09-01).

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Figure 8. Point species richness at each sampling station of the study area (EH-09- 01).

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45 N° of species 1000 Bottom salinity 40 Depth

35

30 100

25 ) m ( h

t 20 p De 15 10

10

5

0 1 787 788 789 790 791 792 794 796 799 800 801 802 803 804 805 806 807 808 809 810 811

Sampling station Figure 9. Relation between species richness and environmental variables (Depth and salinity) (EH-09-01). Stations 808-811: estuarine environment.

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Appendix 1. List of macrobenthic species recorded in the historical study and the EH-09-01 survey (indicated with an asterisk “*”).

Porifera Axinellida unident. Callispongia sp.* Cliona sp. Hadromeridae unident. Mangilia sp. Mixilla sp. Porifera unident. 1* Porifera unident. 2 Porifera unident. 3 Porifera unident. 4 Porifera unident. 5 Porifera unident. 6 Porifera unident. 7 Suberites sp. Tedania sp. Coelenterata Hydrozoa Aglaophenia acacia Amphisbetia operculata Bougainvillidae unident. Clytia gracilis Eudendrium ramosum Hydrozoa unident. 1* Hydrozoa unident. 2 Hydrozoa unident. 3 Hydrozoa unident. 4 Plumulariidae unident.1 Plumulariidae unident.2 23

Sertularella striata Sertularia sp. Tubulariidae unident. Anthozoa Actiniaria unident. 1* Actiniaria unident. 2* Actiniaria unident. 3 Actiniaria unident. 4 Actiniaria unident. 5 Actinostola crassicornis Anthozoan unident. Flabellum sp.* Gorgonacea unident. Hexacorallia unident. Pennatulacea unident. Primnoella sp. Renilla sp.* Sphincteractis sp. Stylatula sp.* Tripalea clavaria* Tripalea sp. Nematoda Adenophorea unident.* Nematoda unident.* Platelminta Polyclada unident. Nemertea Nemertea unident. 1 Nemertea unident. 2 Nemertea unident. 3 Oligochaeta 24

Oligochaeta unident. Polychaeta Admetella ? Aglaophamus sp.* Ampharete sp. Ampharetidae unident. 1* Ampharetiidae unident. 2 Amphicteis sp. Amphictenidae unident.* Antinoe sp. Aphrodita longicornis Aphrodita sp. Aphroditella alta Armandia loboi* Augeneria cf. tentaculata* Capitellidae unident.* Chaetopteridae unident.* Chaetopterus variopedatus Chaetozone sp. Chrysopetalidae unident. Cirratulidae unident. 1* Cirratulidae unident. 2 Diopatra sp. Diopatra viridis* Dodecaceria sp. Drilonereis sp. Eunice argentinensis Eunice frauenfeldi* Eunice magellanica* Flabelligeridae unident. 1 Glycera americana 25

Glyceriformia unident. 1* Glyceriformia unident. 2 Glyceriformia unident. 3 Halosydnella australis Halosydnella brasiliensis Harmothoe sp. Hemipodus olivieri Hermadion magalhaensis Hesionidae unident. Hydroides plateni Hydroides sp. 1 Hydroides sp. 2 Idanthyrsus armatus Idanthyrsus sp.* Lagisca sp. * Lumbrineridae unident. 1* Lumbrineridae unident. 2 Lumbrineriopsis mucronata* Lumbrineris tetraura Lysarete brasiliensis Magelona riojai* Magelona sp. Maldanidae unident. 1* Maldanidae unident. 2 Marphysa aff. galluci Neanthes succinea Nephtyidae unident. Nephtys sp. Nereididae unident. 1* Nereididae unident. 2 Ninoe brasiliensis* 26

Ninoe sp.* Odontosyllis sp. Oenonidae unident.* Onuphidae unident. 1* Onuphidae unident. 2 Onuphis sp. Onuphis tenuis Opheliidae unident.* Owenia fusifomis Paleanotus sp. Pectinariidae unident. Pherusa cf. laevis americana Phyllochaetopterus socialis Phyllodocidae unident.* Pista sp. Pollidorella sp. Polychaeta unident. Polydora sp. Polynoidae unident. 1* Polynoidae unident. 2 Potamilla cf. platensis Potamilla sp. Sabellaria bellis Sabellariidae unident.* Sabellidae unident. 1* Sabellidae unident. 2 Sabellidae unident. 3 Serpulidae unident. 1* Serpulidae unident. 2* Sigalion cirriferum* Spionidae unident. 27

Spirorbidae unident. Steggoa sp. Syllidae unident. 1* Syllidae unident. 2 Terebellidae unident.* Terebellides lanai Thelepus ? sp. Thelepus plagiostoma Travisia amadoi* Travisia sp. Trichobranchidae unident.* Tubificid unident. Typosyllis sp. Sipunculida Sipunculida unident. * Themiste petricola Brachiopoda Magellania venosa* Terebratella dorsata Mollusca Bivalvia Adrana electa Adrana patagonica* Aequipecten tehuelchus* Aloidis caribaea Aloidis lyoni Ameghinomya antiqua Anachis isabellei Anachis paessleri Ancilla tankervillei Angulus gibber* 28

Atrina seminuda Bivalve unident. 1* Bivalve unident. 2* Brachidontes darwinianus Brachidontes rodriguezi Brachidontes sp. Cardita plata Cardium muricatum Chlamys felipponei Corbula patagonica Crassinella lunulata Crassinella marplatensis Crenella divaricata Cyclocardia veluti Darina solenoides Diplodonta patagonica Erodona mactroides Gastrochaena carcellessi Glycimeris longior Hiatella solida Kennerleya patagonica Limatula pygmaea* Lithophaga patagonica Lucapinella henseli Lyonsia patagonica Lyonsia sp.* Macoma uruguayensis Mactra isabelleana* Mactra patagonica Mactra sp. Malettia cumingi 29

Musculus vigor Mytella charruana Mytilus edulis platensis* Natica isabelleana Noetia bisulcata Nucula puelcha Nuculana sulculata Ostrea puelchana Ostrea sp.1 Ostrea sp.2 Ostrea sp.3 Ostrea spreta Panope abbreviata Petricola patagonica Pitaria rostrata Plicatula spondyloidea Pteria hirundo Semele casali Sphenia hatcheri Tagelus plebeius Tegula patagonica Tellina petiti Tellina sp. Terebra doello-juradoi Terebra gemmulata Tivella isabelleana* Transenpitar americana Zygochlamys patagonica* Gastropoda Actaeocina candei Actaeon punctostriatum 30

Adelomelon beckii Adelomelon brasiliana Aesopus metcalferi Anachis isabellei* Anachis paessleri Ancilla tankervillei Argobuccinum magellanicum Ataxocerithium pullum Balcis sp. Buccinanops cochlidium Buccinanops duartei* Buccinanops globosum Buccinanops gradatum Buccinanops lamarckii* Buccinanops uruguayensis Caecum antillarum Caecum sp. Calliostoma consimilis Calliostoma coppingeri* Calliostoma jucundum Calyptraea pileolus Calyptraster sp.* Clathurella aguayoi Conus clenchi Conus iheringi Conus sp.* Corbula patagonica* Crepidula a. aculeata Crepidula protea Crepidula sp.* Crepidula unguiformis 31

Cuspidaria sibilina* Cyclocardia velutinus* Cymatium americanum Cymatium felipponei Drillia brazilienzis Drupa necocheana Epitonium georgettina Epitonium tenuistriatum Eulima auricincta Eulimella argentina Eulimella sp. Fissurellidea hiantula Fisurella sp. Fisurellidae unident. Fusinus frenguellii Glycimeris longior* Glypteuthria agnesia Halistylus circunstriatum Halistylus columna Heleobia australis* Lamellaria sp.* Lamellaridae unident.* Lathyrus frenguelli Mangelia michaelseni Marionia cucullata* Nassarius coppingeri* Natica impervia* Natica isabelleana* Natica sp.* Nucula puelcha* Nudibranchia unident. 1* 32

Nudibranchia unident. 2* Odontocymbiola magellanica* Odostomia multituberculata Odostomia sp. Olivancillaria carcellesi* Olivancillaria urceus Olivancillaria uretai Olivella puelchana* Olivella tehuelchana Paraeuthria rosea Phalium labiatum iheringi Philine argentina* Pleurotomella aguayoi* Pododesmus leloiri Pododesmus rudis Pododesmus sp. Polycera marplatenses Polystira formosissima Pyramidellidae unident. Pyrene isabellei Retusa caelata Terebra gemmulata* Tonna galea brasiliana Trochidae unident. Trophon laciniatus Trophon orbignyi Turbonilla dispar Turbonilla fasciata Turbonilla interrupta Turbonilla sp. 1 Turbonilla sp. 2 33

Turbonilla uruguayensi Urosalpinx rushi Volutidae unident. Volvulella persimilis Zidona duffresnei Scaphopoda Cadulus quadridentatus* Cadulus tetrodon Cephalopoda Argonauta nodosa Octopus tehuelchus Semirossia tenera* Poliplacophora Chaetopleura fulva* Chaetopleura isabellei* Poliplacophora unident. 1 Poliplacophora unident. 2 Picnogonida Picnogonida unident.* Anoplodactylus stictus Pantopoda unident. Crustacea Cirripedia Balanus amphitrite Balanus improvisus Balanus sp.* Balanus trigonus Balanus vetustus niveus Chthamalus bisinuatus Lepadomorpha unident.* Ornatoscalpellun sp.* 34

Scalpellum sp. Ostracoda Ostracoda unident. 1* Ostracoda unident. 2 Ostracoda unident. 3 Ostracoda unident. 4 Amphipoda Amphitoe ramondi Caprellidae unident. Corophium insidiosum Gammaridae unident. 1* Gammaridae unident. 2* Gammaridae unident. 3 Gammaridae unident. 4 Melita orgasmos Phoxocephalopsis zimmeri Isopoda Ancinus depressus Anthuridae unident.* Aselllota unident.* Cirolana sp.* Excirolana armata Flabellifera unident.* Idoteidae unident. 1 Idoteidae unident. 2 Idoteidae unident. 3 Idoteidae unident. 4 Idoteidae unident. 5 Idoteidae unident. 6 Idothea sp. 1 Idothea sp. 2 35

Macrochiridotea robusta Macrochiridotea stebbingi* Macrochiridotea sp. Serolis bonaerensis Serolis gaudichaudi Serolis marplatensis Serolis polaris Sphaeroma sp.* Cumacea Cumacea unident. 1(Eudorella sp?) Cumacea unident. 2 (Dyastilis sp?)* Cumacea unident. 3 (Leptocuma sp?)* Tanaidacea Tanaidaceo unident. Tanais sp. Decapoda Penaeoidea Artemesia longinaris* Peisos petrunkevitchi* Pleoticus muelleri* Pandaloidea Austropandalus grayi* Crangonoidea Pontocaris boschii Anomura Anomura unident. Dardanus arrosor insignes Loxopagurus loxochelis* Paguristes robustus Pagurus comptus* Pagurus criniticornis* 36

Pagurus exilis* Pagurus gaudichaudi Brachyura Callinectes sapidus Chasmagnatus granulatus Coenophtalmus tridentatus Collodes rostratus Collodes rostratus* Corystoides chilensis Cyrtograpsus affinis Cyrtograpsus altimanus Cyrtograpsus angulatus Dissodactylus crinitichelis Ebalia rotundata Ebalia sp. Eurypodius latreillei Leucippa pentagona* Leurocyclus tubeculosus* Libidoclea granaria Libinia spinosa Majidae unident. Metasesarma sp Ovalipes trimaculatus* Ovalipes trimaculatus Pachycheles chubutensis Pachycheles haigae Panopeus meridionalis Panopeus sp. Pelia rotunda* Peltarium spinosulum* Pilumnoides hassleri* 37

Pilumnus reticulatus Pilumnus sp. Pinnixa brevipollex Pinnixa patagoniensis Pinnotheres garthi Pinnotheres maculatus Platyxanthus crenulatus Platyxanthus patagonicus Platyxanthus sp. Portunus sp. Rochinia gracilipes* Tumidotheres maculatus* Ectoprocta Aetea anguina Alcyonidium sp. Briozoa unident. 1* Briozoa unident. 2* Briozoo unident. 3 Briozoo unident. 4 Briozoo unident. 5 Celleporella hyalina Conopeum reticulum Electra monostachys Lunulitiformia unident. Membranipora puelcha Membranipora sp. Membraniporidae unident. 1* Membraniporidae unident. 2 Echinodermata Holothuroidea Cucumaridae unident. 38

Holothuroidea unident.* Pseudocnus dubiosus leoninus* Echinoidea Arbacia dufresnei* Austrocidaris canaliculata* Encope emarginata* Pseudoechinus magellanicus* Sterechinus agassizii Trypilaster sp.* Asteroidea Asteroidea unident. 1* Asteroidea unident. 2 Asteroidea unident. 3 Asteroidea unident. 4 Asteroidea unident. 5 Astropecten b. brasiliensis* Astropecten cingulatus Calyptraster sp. Ctenodiscus australis* Cosmasterias lurida Ctenodiscus australis Echinaster cf. sentus Echinaster sp. Heliaster sp. Labidiaster sp.* Luida sp. Luidia quequensis Patiria stilifer* Ophiuroidea Amphiura eugeniae* Gorgonocephalus chilensis 39

Ophiacanta vivipara Ophiactis asperula* Ophioplocus januari Ophiotrix angulata Ophiuroglypha lymanii* Ophiuroidea unident. Chordata Urochordata (Tunicata) Ascidiacea indet.* Corella sp. Didemnidae unident. Molgula sp.* Sicozoa umbelata* Tunicata unident. 1* Tunicata unident. 2 Tunicata unident. 3 Cephalochordata Branchiostoma platae*

40

Appendix 2. Presence of taxa (X) collected at each sampling station of the EH-09-99 survey.

TAXA EG 787 EG 788 EG 789 EG 790 EG 791 EG 792 EG 794 EG 796 EG 799 EG 800 EG 801 EG 802 Actiniaria indet. 1 - - - - X X - - - X X - Actiniaria indet. 2 - - - - - X ------Adrana patagonica ------Aenonidae ------X - - Aglaophamus sp. ------X X - - Ampharetidae - - - - - X - - X X - - Amphictenidae ------X X - - Amphiura eugeniae X ------Anachis isabellei ------Angulus gibber - - X ------X Arbacia dufresnei ------X - - - - - Armandia loboi X ------Artemesia longinaris X ------Ascidiacea indet. - - - X - - X - - - - - Asteroidea indet. ------X Astropecten b. brasiliensis - - - X X ------X Augeneria cf. tentaculata ------X - Austrocidaris canaliculata ------X - - - - - Austropandalus grayi - - - - X - X - - - - - Balanus sp. X - X ------Bivalvo indet.1 ------X Bivalvo indet.2 ------X - - Branchiostoma platae ------Briozoa Lunularidae ------X - Briozoa ramoso - - - - - X ------Buccinanops lamarckii ------Cadulus quadridentatus - - - X ------X Calliostoma coppingeri - X - - X X - - - - - X Callispongia sp. - - - - - X X - - - - - Calyptraster sp. ------X - - - - - Capitellidae ------41

TAXA EG 787 EG 788 EG 789 EG 790 EG 791 EG 792 EG 794 EG 796 EG 799 EG 800 EG 801 EG 802 Chaetopleura fulva ------X Chaetopleura isabellei - X X ------Chaetopteridae ------X - - - - - Chlamys tehuelchus ------X Cirolana sp. ------X - - - Cirratulidae - - X X X - - - - X X X Collodes rostratus - - - - - X - - - - - X Conus sp. ------X Corbula patagonica X ------Crepidula sp. X - - - X ------Ctenodiscus australis ------X X - - Cuspidaria similina - - - - X ------Cyclocardia velutinus ------X - - Diopatra viridis ------X Dyastilis sp. - - - - - X X - - - X X Encope emarginata X X - X ------Enoplida (nematoda) ------X - - Eunice franenpeldi? - - - - - X ------Eunice magellanica - - - - X ------Flabellum sp. ------X - - - - Gammaridae indet.2 - - - - - X - - X X - - Gammaridae indet.1 - X X X - X X X - X X X Glyceriformia - - - X - - - - - X - - Glycimeris longior X ------Heleobia australis ------Hidrozoa indet. - - X - X X X X - - X X Holoturia indet. ------X - - - Hyatella sp. ------X - - - - - Idhanthyrsus sp. ------X - - Isopoda Anthuridae - - - - - X - - - - - X Isopoda Aselllota - - - X ------X Isopoda Flabellifera ------X - X X - X Labidiaster sp. ------X - - - - - 42

TAXA EG 787 EG 788 EG 789 EG 790 EG 791 EG 792 EG 794 EG 796 EG 799 EG 800 EG 801 EG 802 Lagisca sp. - - - - X X X - X - - X Lamellaria sp. ------X - - - - - Lamellaridae indet. ------X - - - - - Leda patagonica ------X Lepadomorpha indet. - - - - X X - - - - - X Leptocuma sp. X ------X Leucipa pentagona X X ------X Leurocyclus tubeculosus - - - - - X ------Limatula pygmaea ------X - - - - - Loxopagurus loxochelis X ------Lumbrineridae indet. - - - X X X - - X X - X Lumbrineriopsis mucronata ------Macrochiridotea stebbingi ------Mactra isabelleana ------Magellania venosa ------X - - Magelona riojai ------Maldanidae indet. - - - X X X - - X X X X Marionia cucullata - - - - - X ------Membraniporidae indet. X ------Molgula sp. - - - X ------Mytilus edulis platensis - - X ------X Nassarius coppingeri ------X - Natica impervia ------X - - Natica isabelleana ------X - - Natica sp. ------X - - - Nematoda indet. - - - - X - - - - - X X Nereidiidae - - - - X - X - - - - - Ninoe brasiliensis ------Ninoe sp. ------X - Nucula puelcha - - - - X ------Nudibranchia indet. - - - X - - X - - - - - Odontocymbiola magellanica ------X - - Olivancillaria carcellesi ------43

TAXA EG 787 EG 788 EG 789 EG 790 EG 791 EG 792 EG 794 EG 796 EG 799 EG 800 EG 801 EG 802 Olivella puelchana X - - X ------X X Onuphidae ------X - X - - X Ophelidae indet. X ------Ophiactis asperula ------X - - - - Ophiuroglypha lymanii ------X - - - Ornatoscalpellun sp. ------X - - Ostracoda indet. X ------Ovalipes trimaculatus - - X ------Pagurus comptus - - - - - X ------Pagurus criniticornis X ------Pagurus exilis ------Patiria stilifer X ------Peisos petrunkevitchi ------Pelia rotunda - - - X X ------Peltarium spinosulum - - - X ------Pennatulacea indet. - - X ------Philine argentina ------X - - Phyllochaetopterus socialis - - - X ------X Phyllodocidae indet. ------X Picnogonida indet. ------X - - - Pilumnoides hassleri - - - - - X - - - - - X Pleoticus muelleri X ------Pleurotomella aguayoi ------X Polynoidae indet. - X ------X - - Porifera indet. - - - - X ------Pseudocnus dubiosus leoninus ------X - - - - - Pseudoechinus magellanicus - - - X - X - X - - - X Renilla sp. X ------Rochinia gracilipes - - - - - X ------Rossia ternera - - - - X ------Sabellariidae ------X - - - - - Sabellidae ------X - - X - - Serpulidae indet. X - X X - - - - - X - X 44

TAXA EG 787 EG 788 EG 789 EG 790 EG 791 EG 792 EG 794 EG 796 EG 799 EG 800 EG 801 EG 802 Sicozoa unmbelata - - X ------X Sigalion cirriferum ------Sipunculida indet. - - - - X - X - - - X X Sphaeroma sp. ------X Syllidae - - - - - X X - - X - - Terebellidae indet. - X - X - - - X X - - X Terebra gemmulata - - - X ------Tivella isabelleana X ------Travisia amadoi ------X X - Trichobranchiidae ------X X - - Tripalea clavaria - - - X X ------Tripilaster sp. ------X - - Tumidotheres maculatus - - X ------Tunicado colonial indet. ------X X - X - - Zygochlamys patagonica ------X - -

TAXA EG 803 EG 805 EG 807 EG 808 EG 809 EG 809 EG 809 EG 810 EG 810 EG 810 EG 811 EG 811 Actiniaria indet. 1 X ------Actiniaria indet. 2 ------Adrana patagonica - - X ------Aenonidae ------Aglaophamus sp. X ------Ampharetidae ------Amphictenidae ------Amphiura eugeniae ------Anachis isabellei - - X ------Angulus gibber - - X ------Arbacia dufresnei ------Armandia loboi ------Artemesia longinaris - - X X - X ------Ascidiacea indet. ------Asteroidea indet. X ------Astropecten b. brasiliensis X ------45

TAXA EG 803 EG 805 EG 807 EG 808 EG 809 EG 809 EG 809 EG 810 EG 810 EG 810 EG 811 EG 811 Augeneria cf. tentaculata ------Austrocidaris canaliculata ------Austropandalus grayi ------Balanus sp. ------Bivalvo indet.1 X ------Bivalvo indet.2 ------Branchiostoma platae - - X ------Briozoa Lunularidae ------Briozoa ramoso ------Buccinanops lamarckii - - X X ------Cadulus quadridentatus ------Calliostoma coppingeri ------Callispongia sp. ------Calyptraster sp. ------Capitellidae ------X Chaetopleura fulva ------Chaetopleura isabellei ------Chaetopteridae ------Chlamys tehuelchus ------Cirolana sp. X ------Cirratulidae ------Collodes rostratus ------Conus sp. ------Corbula patagonica - - X X ------Crepidula sp. ------Ctenodiscus australis ------Cuspidaria similina ------Cyclocardia velutinus ------Diopatra viridis X - X ------Dyastilis sp. - - X ------Encope emarginata - X ------Enoplida (nematoda) ------Eunice franenpeldi? ------46

TAXA EG 803 EG 805 EG 807 EG 808 EG 809 EG 809 EG 809 EG 810 EG 810 EG 810 EG 811 EG 811 Eunice magellanica ------Flabellum sp. ------Gammaridae indet.2 ------Gammaridae indet.1 ------Glyceriformia - - - X X - - X - - - - Glycimeris longior X ------Heleobia australis ------X - Hidrozoa indet. - - X ------Holoturia indet. ------Hyatella sp. ------Idhanthyrsus sp. ------Isopoda Anthuridae - - X ------Isopoda Aselllota - - X ------Isopoda Flabellifera ------Labidiaster sp. ------Lagisca sp. ------Lamellaria sp. ------Lamellaridae indet. ------Leda patagonica ------Lepadomorpha indet. ------Leptocuma sp. - - - - X X X X X - X X Leucipa pentagona ------Leurocyclus tubeculosus ------Limatula pygmaea ------Loxopagurus loxochelis - - X ------Lumbrineridae indet. ------Lumbrineriopsis mucronata X ------Macrochiridotea stebbingi ------X - Mactra isabelleana - - - - X X X - - - - - Magellania venosa ------Magelona riojai X ------Maldanidae indet. ------Marionia cucullata ------47

TAXA EG 803 EG 805 EG 807 EG 808 EG 809 EG 809 EG 809 EG 810 EG 810 EG 810 EG 811 EG 811 Membraniporidae indet. ------Molgula sp. ------Mytilus edulis platensis ------Nassarius coppingeri ------Natica impervia ------Natica isabelleana ------Natica sp. ------Nematoda indet. - - - X ------X Nereidiidae ------Ninoe brasiliensis - - X ------Ninoe sp. ------Nucula puelcha - - X ------Nudibranchia indet. - - X ------Odontocymbiola magellanica ------Olivancillaria carcellesi - - X ------Olivella puelchana ------Onuphidae ------Ophelidae indet. ------Ophiactis asperula ------Ophiuroglypha lymanii ------Ornatoscalpellun sp. ------Ostracoda indet. ------Ovalipes trimaculatus ------Pagurus comptus ------Pagurus criniticornis - - X X - X ------Pagurus exilis X - X ------Patiria stilifer ------Peisos petrunkevitchi - - - X X X ------Pelia rotunda ------Peltarium spinosulum ------Pennatulacea indet. ------Philine argentina ------Phyllochaetopterus socialis ------48

TAXA EG 803 EG 805 EG 807 EG 808 EG 809 EG 809 EG 809 EG 810 EG 810 EG 810 EG 811 EG 811 Phyllodocidae indet. ------Picnogonida indet. ------Pilumnoides hassleri ------Pleoticus muelleri - - X ------Pleurotomella aguayoi ------Polynoidae indet. ------Porifera indet. ------Pseudocnus dubiosus leoninus ------Pseudoechinus magellanicus ------Renilla sp. ------Rochinia gracilipes ------Rossia ternera ------Sabellariidae ------Sabellidae ------Serpulidae indet. ------Sicozoa unmbelata ------Sigalion cirriferum X ------Sipunculida indet. ------Sphaeroma sp. ------Syllidae ------Terebellidae indet. ------Terebra gemmulata ------Tivella isabelleana ------Travisia amadoi ------Trichobranchiidae ------Tripalea clavaria ------Tripilaster sp. ------Tumidotheres maculatus ------Tunicado colonial indet. X ------Zygochlamys patagonica ------