163Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Inventory of macroalgal epiphytes on the seagrass Thalassia testudinum (Hydrocharitaceae) in Parque Nacional Cahuita, Caribbean coast of Costa Rica Jimena Samper-Villarreal1, Andrea Bernecker1 & Ingo S. Wehrtmann1,2 1. Escuela de Biología, Universidad de Costa Rica, San Pedro, San José 2060, Costa Rica; jimena_samper@yahoo.com 2. Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Universidad de Costa Rica, San José 2060, Costa Rica; ingowehrtmann@gmx.de Received 15-III-2008. Corrected 25-V-2008. Accepted 28-VI-2008. Abstract: Seagrass epiphytes play an important role in seagrass habitats; however, available information from Central America is scarce. The present study focuses on macroalgal epiphytes on leaves of the seagrass Thalassia testudinum in the seagrass meadows at Punta Cahuita, Caribbean coast of Costa Rica, and it is the first one of its kind in Costa Rica. A representative amount for each algal epiphyte species found was collected, preserved and identified to the lowest possible taxon. Preserved samples of each species were deposited in the Herbarium of the Universidad de Costa Rica. A total of 26 species of macroalgae were found: 15 species belong- ing to Rhodophyta, four to Chlorophyta, six to the class Phaeophyceae, and one diatom species which could not be identified. The present inventory reports three species that are new for the phycological flora of Costa Rica, four species are reported for the first time for the Caribbean coast of Costa Rica, and 17 are new reports for the Parque Nacional Cahuita area. Epiphyte species number might further rise if sampling efforts and the study area increased. Rev. Biol. Trop. 56 (Suppl. 4): 163-174. Epub 2009 June 30. Key words: epiphytes, algae, seagrass, Thalassia testudinum, Cahuita, Costa Rica. Seagrass systems serve as a nursery habi- tat for early life stages of many commercially important species that seek protection from predators. They are also important as a feed- ing ground for sea turtles, certain fish, sea urchins, and manatees among others (Humm 1964, Hemminga & Duarte 2000). Moreover, these meadows can promote sediment deposi- tion and also avoid resuspension of sediments and suspended particulate matter, which in turn contributes to the stabilization of the coast (Phillips & Meñez 1988, Hemminga & Duarte 2000, Corlett & Jones 2007). Seagrass leaves provide a suitable sub- strate for macroalgae found as epiphytes, which are just as important, if not more, as primary producers and basis for a variety of grazers (Humm 1964, Ballantine & Humm 1975, Heijs 1984, van Montfrans et al. 1984, Moncreiff et al. 1992, Armitage et al. 2006). Epiphytes can also serve as a protection layer for seagrasses from excessive UV radiance, and diminish desiccation effects during periods of exposure to air (van Montfrans et al. 1984, Littler & Littler 1999). On the other hand, epiphyte load on submersed macrophytes increases as leaf age increases (Humm 1964), and is determined by colonization rate and lifespan of the leaf (Heijs 1984). As epiphyte load increases, it can negatively affect seagrasses mainly by (1) diminishing photosynthesis due to competition for light, (2) competing for nutrients, and by (3) complete or partial leaf loss due to epiphyte related senescence, hervibory, and other biotic factors, and/or increased hydrodynamic drag by waves, currents, storms, and other abiotic 164 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 factors (Heijs 1984, van Montfrans et al. 1984, Littler & Littler 1999, Drake et al. 2003). The most widely distributed seagrass in the Caribbean is Thalassia testudinum Banks ex König, which provides ample substrate for algal epiphytes (Humm 1964, Cho et al. 2002, Barrios & Díaz 2005, Corlett & Jones 2007). The seagrasses in Parque Nacional Cahuita have been scarcely studied in recent years, focusing primarily on biomass, productivity, and seasonality of reproduction in T. testudi- num (Paynter et al. 2001, Fonseca et al. 2007, Nielsen 2007). Our knowledge regarding sea- grass epiphytes from the Caribbean of Costa Rica is extremely limited. The only report of macroalgae as seagrass epiphytes was pub- lished by Kemperman (1986), who mentioned the substrate of two macroalgal species from the Caribbean of Costa Rica. The present study aims to provide an inventory of algal species found as epiphytes on T. testudinum leaves in the seagrass mead- ows at Parque Nacional Cahuita. The results may contribute to a more complete picture of the algal diversity of the Caribbean coast of Costa Rica, and aims to serve as a first step for a better understanding of the ecological processes governing the dynamics of seagrass meadows in the area. MATERIALS AND METHODS The study area (Fig. 1) is located in the seagrass meadows dominated by the turtle grass T. testudinum (for review of seagrasses in Costa Rica, see Cortés & Salas 2008) at Punta Cahuita (9°44’; 82°48’), Caribbean coast of Costa Rica. This site was selected due to the presence of abundant and highly productive seagrass meadows (Paynter et al. 2001). Four 50m transects were positioned parallel to the coast, and among each other, at an increasing distance from the coast line (50, 100, 150 and 200m from the coast, respectively). The depth varied between 0.3 and 2.5m, not necessarily in response to distance to the shore, but related to seagrass patch distribution. Sampling was carried out in March, June and September of 2006. When examining the above-mentioned transects, a representative amount of T. testudinum leaves, which contained different species of algal epiphytes, were collected. Samples were preserved in formaldehyde 3% Fig. 1. Location of the study site at Parque Nacional Cahuita, Caribbean coast of Costa Rica. 86º0’00” W 84º0’00” W 82º49’00” W 9º 44 ’4 6” N 10 º0 ’0 ” N 8º 0’ 0” N Pacific Ocean Costa Rica Parque Nacional Cahuita Caribbean Sea Nicaragua Panama 0 20 40 80 120 160 Punta Cahuita Sampling location km km 0 0.25 0.5 1 1.5 2 165Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 in sea water, transported to the laboratory at the Universidad de Costa Rica, San José, and identified to the lowest possible taxon. Some of the species could not be identified due to the small amount of material found on the leaves; juvenile forms were excluded from species identification when lacking the neces- sary structures for identification. The following publications were used for species identifica- tion: Taylor (1960), Dawson (1962) and Littler & Littler (2000). Representatives of each algal species found were deposited in the Herbarium (USJ) of the Escuela de Biología, Universidad de Costa Rica. According to personal observations and unpublished data by the first two authors, the abundance of the species was arbitrarily grouped into the following categories: very abundant (present in all three sample dates and in large quantities), abundant (found only in one-two sample dates and not in large quanti- ties), and rare (found only once during sample period and in small quantities). RESULTS A total of 26 species of macroalgae (18 genera) were found as epiphytes on T. testudi- num leaves (Table 1). Fifteen species belonged to Rhodophyta, four to Chlorophyta, six to Phaeophyceae, and one species of sheathed dia- toms which could not be identified. Four species represent new records for the Caribbean coast of Costa Rica, and 17 species are reported for the first time in Parque Nacional Cahuita (Table 1). Furthermore, three species are reported for the first time for the phycological flora of Costa Rica (Bryopsis pennata, Champia salicornioides, and Kützingiella elachistaeformis). The most frequently encountered species (Table 1) in our study were Titanoderma pus- tulatum and Pneophyllum fragile (red coralline encrusting forms), followed by Dictyota cer- vicornis and D. pulchella (brown algae), and Ceramium flaccidum, Champia salicornioides, and Wrangelia bicuspidata (red algae). The following is a list of all epiphyte species found during the study. It includes the collection number for material deposited in the Herbarium of the Escuela de Biología, Universidad de Costa Rica, and information concerning distribution and known habitat for each species. World Distribution Code: A = Antarctic; AA = Australasia; C = Caribbean; CEP = Central East Pacific; EA= eastern Atlantic; HW = Hawaiian Islands; I = Indian Ocean; M = Mediterranean; NEA / NEP = northeastern Atlantic / Pacific; NWA / NWP = northwestern Atlantic / Pacific; RS = Red Sea; SEA / SEP = southeastern Atlantic / Pacific; SWA /SWP = southwestern Atlantic / Pacific; WA /WP = western Atlantic / Pacific CHLOROPHYTA Class Bryopsidophyceae Family Bryopsidaceae Bryopsis hypnoides J.V. Lamouroux USJ - 73886 World distribution: NEA, SEA, NWA, C, SWA, M, RS, I, CEP, HW, SEP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater Antilles, southern and east- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Mangrove prop roots or other hard substrates, coral fragments and other hard substrates. Lower intertidal to 1m depth, wave beaten (Littler & Littler 2000, Bernecker 2008). * Bryopsis pennata J.V. Lamouroux USJ - 73914 World distribution: SWA, C, I, CEP (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Mangrove prop roots or other solid substrate, rocks. Shallow waters, lower intertidal to 5m depth (Littler & Littler 2000, Bernecker 2008). *New record for Costa Rica. 166 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 TABLE 1 List and frequency of occurrence of macroalgal epiphytes encountered in the present study related to the species lists available for Cahuita, Caribbean coast of Costa Rica, and species previously reported as epiphytes on seagrasses Taxa Occurrence Cahuita Caribbean coast Epiphyte on seagrasses CHLOROPHYTA Bryopsis hypnoides rare * Bernecker 2008 na †Bryopsis pennata rare * Kemperman 1986‡, Bernecker 2008‡ na Chaetomorpha linum rare * Kemperman 1986, Bernecker 2008 na Cladophora albida rare * * na PHAEOPHYTA Dictyopteris delicatula rare Wellington 1974, Kemperman 1986 Kemperman 1986, Soto & Ballentine 1986, Bernecker 2008 na Dictyota cervicornis very abundant Wellington 1974 Soto & Ballentine 1986, Bernecker 2008 na Dictyota mertensii rare Dawson 1962, Kemperman 1986 Kemperman 1986, Bernecker 2008 Bernecker 2008 Dictyota pulchella very abundant * Bernecker 2008 Littler & Littler 2000, Bernecker 2008 Hincksia mitchelliae rare * Bernecker 2008 na †Kuetzingiella elachistaeformis rare * * Humm 1964, Littler & Littler 2000 RHODOPHYTA Amphiroa fragilissima rare Wellington 1974 Kemperman 1986, Soto & Ballentine 1986, Bernecker 2008 Frankovich & Fourqurean 1997 Ceramium brevizonatum rare Kemperman 1986 Kemperman 1986, Bernecker 2008 Bernecker 2008 Ceramium brevizonatum var. caraibicum abundant * * na Ceramium cimbricum rare * Bernecker 2008 na Ceramium flaccidum very abundant * Bernecker 2008 Littler & Littler 2000, Bernecker 2008 †Champia salicornioides very abundant * * Littler & Littler 2000 167Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Taxa Occurrence Cahuita Caribbean coast Epiphyte on seagrasses Crouania attenuata rare Kemperman 1986 Kemperman 1986, Bernecker 2008 Humm 1964, Bernecker 2008 Herposiphonia secunda rare * Kemperman 1986, Bernecker 2008 Littler &Littler 2000, Barrios & Díaz 2005, Bernecker 2008 Hypnea spinella abundant Kemperman 1986, Wellington 1974 Kemperman 1986, Soto & Ballentine 1986, Bernecker 2008 Barrios & Díaz 2005, Bernecker 2008 Jania capillaceae rare * Kemperman 1986, Bernecker 2008 Humm 1964, Littler & Littler 2000, Bernecker 2008 Pneophyllum fragile very abundant * Bernecker 2008 Littler &Littler 2000, Bernecker 2008 Polysiphonia c.f. howei rare * Kemperman 1986, Bernecker 2008 Littler & Littler 2000, Bernecker 2008 Titanoderma pustulatum very abundant * Bernecker 2008 Littler & Littler 2000, Bernecker 2008 Wrangelia argus abundant Wellington 1974 Kemperman 1986, Soto & Ballentine 1986, Bernecker 2008 Humm 1964, Littler & Littler 2000, Barrios & Díaz 2005, Bernecker 2008 Wrangelia bicuspidata abundant * Bernecker 2008 Bernecker 2008 BACILLARIOPHYCEAE Sheathed diatoms rare - - - † new report for Costa Rica. * new report for Cahuita or the Caribbean coast of Costa Rica. na: no information available. ‡ species reported: Bryopsis pennata var. leprieurii. TABLE 1 (Continued) List and frequency of occurrence of macroalgal epiphytes encountered in the present study related to the species lists available for Cahuita, Caribbean coast of Costa Rica, and species previously reported as epiphytes on seagrasses 168 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Class Ulvophyceae Family Cladophoraceae Chaetomorpha linum (O.F. Müller) Kützing USJ - 73848 World distribution: NEA, SEA, NWA, C, M, SWA, RS, I, NWP, NEP, SWP, CEP, SEP, AA, A (Bernecker 2008). Caribbean distribu- tion: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: As mats or mounds lying free in high-nutrient areas (near bird islands); up to 3m deep (Littler & Littler 2000). Cladophora albida (Nees) Kützing USJ - 73900 World distribution: NEA, NWA, NEP, SWA, C, AA, NWP, M (Guiry & Guiry 2007). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: In protected or wave-exposed areas, on hard substrates. Upper intertidal down to 3m depth (Littler & Littler 2000). PHAEOPHYTA Family Acinetosporaceae Hincksia mitchelliae (Harvey) P.C. Silva USJ - 73885 World distribution: NEA, EA, NWA, SWA, C, M, RS, I, WP, NEP, SEP, HW, SWP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Inconspicuous, on rocks, hard substrates or epiphytic on other algae, often found as brown fuzz on mangrove prop roots. Less than 1m depth (Littler & Littler 2000, Bernecker 2008). Family Dictyotaceae Dictyopteris delicatula J.V. Lamouroux USJ - 73869, 73870, 73879 World distribution: SEA, NEA, SWA, C, I, NEP, NWP, SWP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: On mangrove prop roots, coral fragments or other hard substrates; from inter- tidal down to 12m, rarely 30m deep (Littler & Littler 2000, Bernecker 2008). Dictyota cervicornis Kützing USJ - 73853, 73857, 73867, 73906, 73920, 73922, 73923, 73924 World distribution: SEA, NEA, SWA, C, I, RS, NWP, SWP (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Attached to rocks, coral frag- ments, shell fragments or large plants in sandy shallow areas. Down to 3m depth (Littler & Littler 2000, Bernecker 2008). Dictyota mertensii (Martius) Kützing USJ - 73921, 73925 World distribution: SEA, NEA, C, NWP, SWP (Bernecker 2008). Caribbean distribu- tion: Florida, Bahamas, Greater and Lesser Antilles, and southern Caribbean (Littler & Littler 2000). Habitat: In moderately wave-exposed areas where fish grazing is minimal; epiphytic. Intertidal down to 15m depth (Littler & Littler 2000, Bernecker 2008). Dictyota pulchella Hörnig and Schnetter USJ-73845, 73847, 73872, 73905, 73906, 73911, 73916, 73919, 73926 169Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 World distribution: SEA, NEA, C (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: On dead coral, shell fragments, other hard substrates, mangrove peat or epi- phytic on seagrass and coarse algae; in shallow areas with calm water. Intertidal down to 70m depth (Littler & Littler 2000, Bernecker 2008). Family Ectocarpaceae *† Kuetzingiella elachistaeformis (Heydrich) M. Balakrishnan and Kinkar USJ - 73908 as Ectocarpus elachistaeformis Heydrich World distribution: NWA, SWA, M, AA (Guiry & Guiry 2007). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Inconspicuous, epiphytic on coarse algae, seagrasses or mangrove prop roots. Intertidal down to 1m depth (Littler & Littler 2000). *New record for Costa Rica. † Ectocarpus elachistaeformis Heydrich is cur- rently a synonym of Kuetzingiella elachistae- formis (Heydrich) M. Balakrishnan and Kinkar (see Balakrishnan & Kinkar 1981). RHODOPHYTA Class Florideophyceae Family Corallinaceae Amphiroa fragilissima (Linnaeus) J.V. Lamouroux USJ - 73877, 73878 World distribution: NEA, SEA, NWA, SWA, C, M, RS, I, CEP, SEP, HW, SWP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Lightly attached to hard sub- strate, in crevices, amongst seagrasses or other algae. Down to 60m depth (Littler & Littler 2000, Bernecker 2008). Jania capillaceae Harvey USJ- 82580 World distribution: SEA, NEA, NWA, SWA, C, RS, I, CEP, SWP (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Epiphyte on other marine plants, in calm waters. Down to 15m depth (Littler & Littler 2000, Bernecker 2008). Pneophyllum fragile Kützing USJ - 73511, 73517, 73873, 73874, 73875, 73876, 73887, 73896, 73897, 73898, 73901, 73910, 73913 World distribution: NEA, NWA, SWA, C, M, RS, I, NWP, CEP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Inconspicuous, epiphytic on macroalgae or seagrasses. Down to 10m depth (Littler & Littler 2000, Bernecker 2008). Titanoderma pustulatum (J.V. Lamouroux) Nägeli USJ - 73510, 73873, 73874, 73875, 73876, 73887, 73896, 73897, 73898, 73901, 73910 World distribution: NEA, SWA, NWA, C, M, I, RS, NEP, SWP, AA, A (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Epiphytic on seagrasses or coarse algae. Down to 5m depth (Littler & Littler 2000, Bernecker 2008). 170 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Family Ceramiaceae Ceramium brevizonatum H.E. Petersen USJ- 82579 World distribution: SWP, I (Bernecker 2008). Caribbean distribution: not available. Habitat: epiphytic (Bernecker 2008). Ceramium brevizonatum var. caraibicum H.E. Petersen & Børgesen USJ-73852, 73889, 73915 World distribution: NWA, C, SWA, I (Guiry & Guiry 2007). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: On dead coral or epiphytic on other algae; down to 1m depth (Littler & Littler 2000). Ceramium cimbricum H.E. Petersen USJ - 73852, 73889, 73915 World distribution: NEA, M, C, NEP, NWP, I, AA, SEP (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Entangled or epiphytic on coars- er algae, on mangrove prop roots or other sub- merged wood. Down to 40m depth (Littler & Littler 2000, Bernecker 2008). Ceramium flaccidum (Harvey ex Kützing) Ardissone USJ-73854, 73861, 73864, 73865, 73866, 73871, 73890, 73892, 73893, 73917 World distribution: NWA, SWA, M, C, NEA, I, SEA, HW, SWP, SEP, AA, CEP (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and the Gulf of Mexico (Littler & Littler 2000). Habitat: Epiphytic on seagrasses or coarser or coarser algae, on submerged wood. Down to 22m depth (Littler & Littler 2000, Bernecker 2008). Crouania attenuata (C. Agardh) J. Agardh USJ-73899 World distribution: C, M, NEA, NWP, SWP, I, AA, SEP, CEP, RS (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean (Littler & Littler 2000). Habitat: Inconspicuous, often tangled among coarser species, epiphytic. Down to 20m depth (Littler & Littler 2000, Bernecker 2008). Wrangelia argus (Montagne) Montagne USJ-73858, 73880 World distribution: SEA, NEA, C, SWA, NWA, I, SWP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Frequently covering large areas on rocky substrates or epiphytic on coarser plants. Down to 10m depth (Littler & Littler 2000, Bernecker 2008). Wrangelia bicuspidata Børgesen USJ-73443, 73854, 73881 World distribution: C, SWP, NWP, I (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: Epiphytic on larger algae. Down to 40m depth (Littler & Littler 2000, Bernecker 2008). 171Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Family Hypneaceae Hypnea spinella (C. Agardh) Kützing USJ-73849, 73856, 73882, 73883, 73884, 73909 World distribution: SEA, NEA, SWA, NWA, C, M, RS, I, HW, SWP, SEP, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: On rocks, coral fragments or epiphytic on larger seaweeds. Intertidal down to 30m depth (Littler & Littler 2000, Bernecker 2008). Family Rhodomelaceae Herposiphonia secunda (C. Agardh) Ambronn USJ-73846 World distribution: C, SWA, NWA, SEA, NEA, M, CEP, SWP, NWP, I, HW, AA (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and western Caribbean, and Gulf of Mexico (Littler & Littler 2000). Habitat: On hard substrates, or epiphytic on larger plants and animal. High intertidal down to 2m depth (Littler & Littler 2000, Bernecker 2008). Polysiphonia c.f. howei Hollenberg USJ-73893 World distribution: SWA, NWA, C, SEA, NEA, SWP, I, AA, CEP, HW (Bernecker 2008). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles, southern and west- ern Caribbean, and the Gulf of Mexico (Littler & Littler 2000). Habitat: On rocks and other hard surfaces, or epiphytic on seagrasses and larger algae. Intertidal to shallow subtidal (Littler & Littler 2000, Bernecker 2008). Family Champiaceae *Champia salicornioides Harvey USJ-73844, 73859, 73862, 73863, 73888, 73894, 73895, 73903 World distribution: AA, I, SEA, SWA, C, NWA, NWP (Guiry and Guiry 2007). Caribbean distribution: Florida, Bahamas, Greater and Lesser Antilles and southern Caribbean (Littler & Littler 2000). Habitat: Attached to hard substrates or epiphytic on seagrasses or other algae; down to 27m depth (Littler & Littler 2000). *New record for Costa Rica. Phylum HETEROKONTOPHYTA Class Bacillariophyceae Sheathed Diatoms USJ-73901, 73904, 73907, 73912, 73917, 73918 Specimens of sheathed diatoms were found forming groups of algae visible to the unaided eye in the field, but species identification was not possible. DISCUSSION The present study represents the first specific contribution on seagrass epiphytes in the Caribbean of Costa Rica. Previously, Kemperman (1986) reported Sphacelaria trib- uloides Meneghini and Polysiphonia gorgoniae Harvey as epiphytic on seagrasses in Puerto Vargas at Cahuita; however, neither species was encountered during this study. The dominance of red coralline encrusting species in our study (Titanoderma pustulatum and Pneophyllum fragile) coincides with pre- vious studies in which coralline algae domi- nated as epiphytes on seagrass leaves (Humm 1964, Corlett & Jones 2007). Humm (1964) found that coralline algae (e.g., Melobesia and Fosliella) formed a coat covering older T. testudinum leaves completely, and assumed that these leaves may die earlier due to the stress for light competition and increased weight. Coralline epiphytes also contribute to sedi- ment supply in seagrass habitats (Humm 1964, Walker & Woelkerling 1988, Corlett & Jones 2007), driven by continuous leaf production and decay, as well as algal growth rate (Walker & Woelkerling 1988). Encrusting forms affect 172 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 the leaves they are directly attached to but have no shading effect on subsequent leaves, as opposed to foliose algae (Humm 1964). Thus, differences in epiphyte species composition may have varying physiological and ecological consequences on seagrasses. Of the species encountered, 16 have been previously reported as seagrass epiphytes for the region; as far as we know, the remain- ing species have not yet been classified as T. testudinum epiphytes (Table 1). Three species (Bryopsis pennata, Champia salicornioides and Kützingiella elachistaeformis) represent new reports for the phycological flora of Costa Rica, four species are new reports for the Caribbean coast of Costa Rica, and 17 spe- cies are new reports for the Parque Nacional Cahuita. The high amount of newly reported species reflects the lack of previous studies focusing on seagrass epiphytes and the low number of algal studies in the area (Wellington 1973, 1974, Soto & Ballentine 1986). In a study focused on the characterization of seagrass epiphyte species and abundance for monitoring purposes in the Gulf of México, Cho et al. (2002) found 13 species of algal epi- phytes of T. testudinum. Our study surpassed that of Cho et al. (2002) in species number; however, none of the reported species coin- cided. Humm (1964) found in Florida a total of 113 species of algal epiphytes on T. testudinum. Later on, Ballantine & Humm (1975) reported 66 epiphyte species commonly found on all four seagrass species studied (T. testudinum, Syringodium filiforme, Diplantera wrightii, and Halophila engelmannii). This reduced number might be related to the considerably smaller study area in the latter, although algal epiphyte species composition is known to vary accord- ing to many environmental variables, such as tides, currents, salinity, available light, depth, leaf turnover rate, nutrients and temperature (Humm 1964, Frankovich & Fourqurean 1997, Hemminga & Duarte 2000). Moreover, epi- phytes show seasonal variation (Humm 1964, Hemminga & Duarte 2000), which might fur- ther explain the variation in the total number of species found in different studies. A recent study on T. testudinum epiphytes in Venezuela (Barrios & Díaz 2005) reported 34 genera and 40 species as epiphytes. The number of both genera and species encoun- tered by Barrios & Díaz (2005) are higher than those encountered in our study (18 gen- era and 26 species). Both studies share only eight genera (Chaetomorpha, Cladophora, Ectocarpus, Jania, Ceramium, Wrangelia, Hypnea, Polysiphonia, and Champia) and two species (Wrangelia argus and Hypnea spinella). Interestingly, the results obtained by Barrios & Díaz (2005) are based upon a one-year monthly sampling period, covering four different sites, while our results are restricted to a much more limited data set (three sample dates at a single sample location). Therefore, it is reasonable to expect that a more prolonged sampling period with a broader study area should increase the number of seagrass epiphyte species at Cahuita. The present study provides a preliminary list of T. testudinum macroalgae epiphyte spe- cies in the Parque Nacional Cahuita meadows, and represents a baseline for future studies on algal epiphytes and seagrass leaf dynamics in the area. The continued study of seagrass epi- phytes (biomass, seasonality and species com- position) in the area is important, as it has been shown that increases in nutrient levels in coast- al areas can alter the balance among marine primary producers, cause changes in water col- umn transparency, and can lead to an increase of seagrass epiphyte biomass (van Montfrans et al. 1984, Frankovich & Fourqurean 1997, Hemminga & Duarte 2000, Gil et al. 2006) which could have a detrimental effect on sea- grass distribution, abundance and productivity (Hemminga & Duarte 2000, Drake et al. 2003). Nutrient increases can also promote the pres- ence of faster growing opportunistic species (van Montfrans et al. 1984, Armitage et al. 2006, Gil et al. 2006), and an alteration in pri- mary producers species composition may affect higher trophic levels (Heijs 1984, Armitage et al. 2006, Gil et al. 2006). The results of the present study may serve as a base for the development of monitoring programs, which 173Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 might focus partially on possible variations in species composition of seagrass epiphytes as a consequence of changes in environmental conditions. ACKNOWLEDGMENTS The project was partially financed by the Vicerrectoría de Investigación of the Universidad de Costa Rica (No. 808-A6-074), and the German Academic Exchange Service (DAAD). The authors are grateful to Margarita Silva (Universidad de Costa Rica) for her help with diatom identification, and to Vanessa Nielsen for her assistance in the field. We are thankful to the following students of the Universidad de Costa Rica for assistance with the preparation of col- lected material deposited in the USJ herbarium collection: Amandine Bourg, Maricel Pizarro, Carolina Seas, Yariela Ugalde, Gloria Vargas, and Carmen Vásquez. Catalina Benavides and Jeffry Ortiz helped us with the preparation of the figure, which is greatly appreciated. The Nature Conservancy facilitated us the bathymetrical model included in the figure. RESUMEN Los epífitos de pasto marino juegan un papel impor- tante en el hábitat de pastos marinos. Sin embargo, la información disponible sobre este tema en América Central es muy limitada. Este estudio se enfoca en las macroalgas epífitas de hojas del pasto marino Thalassia testudinum en las praderas de pasto marino de Punta Cahuita, costa Caribe de Costa Rica y es el primero de su tipo para Costa Rica. Una cantidad representativa para cada especie de epífito algal encontrada se colectó, preservó e identificó al menor taxon posible. Muestras preservadas para cada especie fue- ron depositadas en el Herbario de la Universidad de Costa Rica (USJ). Se encontró un total de 26 especies de macroal- gas: 15 especies de Rhodophyta, cuatro de Chlorophyta, seis pertenecientes a la clase Phaeophyceae y una especie de diatomea que no fue posible identificar. El inventario reporta tres especies por primera vez para la flora fico- lógica de Costa Rica, cuatro especies son reportadas por primera vez para el Caribe de Costa Rica y 17 especies son nuevos reportes para el Parque Nacional Cahuita. Se comparan nuestros resultados con aquellos obtenidos en estudios similares en la región y se especula que el número de especies de epífitos podría aumentar de ser ampliado el esfuerzo de recolecta y el área de estudio. Palabras clave: epífitos, algas, pasto marino, Thalassia testudinum, Cahuita, Costa Rica. REFERENCES Armitage, A.R., T.A. Frankovich & J.W. Fourqurean. 2006. Variable responses within epiphytic and ben- thic microalgal communities to nutrient enrichment. Hydrobiologia 549: 423-435. Balakrishnan, M.S. & V.N. Kinkar. 1981. A taxonom- ic account of Indian Ectocarpales and Ralfsiales. Seaweed Res. Util. 4: 1-57. Ballantine, D. & H.J. Humm. 1975. Benthic algae of the Anclote estuary I. Epiphytes of seagrass leaves. Flor. Sci. (Quart. J. Fla. Acad. Sci.) 38: 150-162. Barrios, J. & O. Díaz. 2005. Algas epífitas de Thalassia testudinum en el Parque Nacional Mochima, Venezuela. Bol. Centr. Invest. Biol. 39: 1-14. Bernecker, A. 2008. Marine Benthic Algae, p. 109-117; Species list: CD p. 17-70. In I.S Wehrtmann & J. Cortés (eds). Marine Biodiversity of Costa Rica, Central America. Monographiae Biologicae, Vol. 86. Springer and Business Media B.V., Berlin, Germany. Cho, T.O., S. Fredericq & K.K. Yates. 2002. Characterization of macroalgal epiphytes on Thalassia testudinum in Tampa Bay, Florida. J. Phycol. 38: 4. Corlett, H. & B. Jones. 2007. Epiphyte communities on Thalassia testudinum from Grand Cayman, British West Indies: their composition, structure, and contri- bution to lagoonal sediments. Sediment. Geol. 194: 245-262. Cortés, J. & E. Salas. 2008. Seagrasses, p. 119-122; Species list: CD p. 71-72. In I.S. Wehrtmann & J. Cortés (eds). Marine Biodiversity of Costa Rica, Central America. Monographiae Biologicae, Vol. 86. Springer and Business Media B.V., Berlin, Germany. Dawson, E.Y. 1962. Additions to the marine flora of Costa Rica and Nicaragua. Pac. Nat. 3: 375-395. Drake, L.A., F.C. Dobbs & R.C. Zimmerman. 2003. Effects of epiphyte load on optical properties and photosyn- thetic potential of the seagrass Thalassia testudinum Banks ex König and Zostera marina L. Limnol. Oceanogr. 48: 456-463. Gil, M., A.R. Armitage & J.W. Fourqurean. 2006. Nutrient impacts on epifaunal density and species composi- tion in a subtropical seagrass bed. Hydrobiologia 569: 437-447. 174 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 56 (Suppl. 4): 163-174, December 2008 Fonseca, A.C., V. Nielsen & J. Cortés. 2007. Monitoreo de pastos marinos en Perezoso, sitio CARICOMP en Cahuita, Costa Rica. Rev. Biol. Trop. 55: 55-66. Frankovich, T.A. & J.W. Fourqurean. 1997. Seagrass epiphyte loads along a nutrient availability gradient, Florida Bay, USA. Mar. Ecol. Prog. Ser. 159: 37-50. Heijs, F.M.L. 1984. Annual biomass and production of epi- phytes in three monoespecific seagrass communities of Thalassia hemprichii (Enrenb.) Aschers. Aquat. Bot. 20: 195-218. Hemminga, M.A. & C.M. Duarte. 2000. Seagrass Ecology. Cambridge University, Cambridge, United Kingdom. Humm, H.J. 1964. Epiphytes of the sea grass Thalassia testudinum, in Florida. Bull. Mar. Sci. Gulf Carib. 14: 306-341. Kemperman, T.C.M. 1986. The marine benthic algae of the Atlantic side of Costa Rica. Brenesia 25-26: 99-122. Moncreiff, C.A., M.J. Sullivan & A.E. Daehnick. 1992. Primary production dynamics in seagrass beds of Mississippi Sound: the contributions of seagrass, epiphytic algae, sand microflora, and phytoplankton. Mar. Ecol. Prog. Ser. 87: 161-171. Littler, M.M. & D.S. Littler. 1999. Blade abandonment/ proliferation: a novel mechanism for rapid epiphyte control in marine macrophytes. Ecology 80: 1736- 1746. Littler, D.S. & M.M. Littler. 2000. Caribbean Reef Plants: An Identification Guide to the Reef Plants of the Caribbean, Bahamas, Florida and Gulf of Mexico. Off Shore Graffics, Inc. Washington, USA. Nielsen, V. 2007. Abundancia, biomasa y floración de Thalassia testudinum (Hydrocharitaceae) en el Parque Nacional Cahuita, Caribe de Costa Rica. Tesis de Licenciatura. Universidad de Costa Rica, San José, Costa Rica. Paynter, C.K., J. Cortés & M. Engels. 2001. Biomass, productivity and density of the seagrass Thalassia testudinum at three sites in Cahuita National Park, Costa Rica. Rev. Biol. Trop. 49 (Suppl. 2): 265-272. Phillips, R.C. & E.G. Meñez. 1988. Seagrasses. Smiths. Contr. Mar. Sci. 34. Smithsonian Institution, Washington, USA. Soto, R. & D.L. Ballentine. 1986. La flora bentónica del Caribe de Costa Rica (notas preliminares). Brenesia 25-26: 123-162. Taylor, W.R. 1960. Marine Algae of the Eastern Tropical and Subtropical Coast of the Americas. Lord Baltimore Press. Michigan, USA. van Montfrans, J., R.L. Wetzel & R.J. Orth. 1984. Epiphyte-grazer relationships in seagrass meadows: consequences for seagrass growth and production. Estuaries 7: 289-309. Walker, D.I. & W.J. Woelkerling. 1988. Quantitative study of sediment contribution by epiphytic coralline red algae in seagrass meadows in Shark Bay, Western Australia. Mar. Ecol. Prog. Ser. 43: 71-77. Wellington, G.M. 1973. Additions to the Atlantic benthic flora of Costa Rica. Brenesia 2: 17-20. Wellington, G.M. 1974. The benthic flora of Punta Cahuita: annotated list of species with additions to the Costa Rican Atlantic flora. Brenesia 3: 19-30. REFERENCE FROM INTERNET Guiry, M.D. & G.M. Guiry. 2007. AlgaeBase version 4.2. World-wide electronic publication, National University of Ireland, Galway (Download: 29 November 2007; http://www.algaebase.org)