586 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.3, 1977

LITERATURECITED Rickenbacker Causeway, Miami, Florida 33149; (P.N.F.) Graduate School of OceU1IORraphy, Uni- Atwood, D. K., J. R. Polifka, and C. P. Duncan. versity of Rhode Island, Kingston, Rhode Island 1975. Temporal Variations in Mass Trans- 02881. port in the Eastern . Proceed- ings of the Eleventh Meeting of the Associa- tion of Island Marine Laboratories of the Caribbean, St. Croix, U.S. Virgin Islands, 1-4 May. Brucks, T. 1971. Currents of the Caribbean and MONA PASSAGE DRIFT BOTTLE adjacent regions as deduced from drift-bottle STUDY studies. Bull. Mar. Sci. 21: 455-465. Corredor, J. (Rapporteur). 1976. Report of William G. Metcalf, Marvel C. Stalcup, and UNESCO/JOC/FAO, and UNEP Sponsored Workshop on Marine Pollution in the Carib- Donald K. Atwood bean and Adjacent Regions. Port of Spain, Trinidad, 13-17 December. ABSTRACT-In September 1973, 423 drift bottles Ichiye, T. 1972. Experiments on Circulation of were released in the vicinity of Mona Passage be- the Gulf of Mexico and the Caribbean Sea tween and Hispaniola. Over the next with a Rotating Tank. Proceedings of IV year 29 (7%) returns were received, all of them Congreso Nacional de Oceanografia, Mexico, from positions west of their launch sites. The November 1969. returns indicated an extremely complex current Maul, G. A., D. R. Norris, and W. R. Johnson. 1974. Satellite photography of eddies in the condition in Mona Passage with some bottles drift- Gulf Loop Current. Geophysical Research ing from the Caribbean into the Letters. 1: 256-258. and others in the opposite direction. Approxi- Molinari, Robert. 1976. Personal communica- mately half the returns came from the Dominican tion regarding satetlite tracked drogues Republic and other nearby points less than 1,000 launched by NOAA and Nova University in km from their launch sites. All remainder drifted October 1975 and January 1976. more than 2,000 km and were recovered from the Nowlin, W. D., Jr. 1971. Water masses and western end of the Caribbean Sea, the Gulf of general circulation of the Gulf of Mexico. Mexico and the east coast of Florida. This long Oceanology International, Feb.: 173-178. Richards, W. J., and J. R. Goulet, Jr. 1976. An drifting group moved at speeds up to at least 21 operational surface drift model used for study- em/sec though the true speed cannot be deter- ing larval lobster recruitment and dispersal. mined. In Proceedings of CICAR II, Symposium on progress in marine research in the Caribbean and adjacent regions, Caracas, Venezuela, 12 During 20-24 September, 1973, on Cruise to 16 July, 1976. Available from JOC/ No. 73-24 of the R/V CRAWFORDof the UNESCO, Paris. University of Puerto Rico, 432 drift bottles Stalcup, M. Co, and W. G. Metcalf. 1972. Cur- rent measurements in the passages of the similar to those described by Bumpus and Lesser Antilles. J. of Geophysical Research, Lauzier (1965) were released in the vicinity 77: 1032-1049. of Mona Passage between the islands of U.S. Naval Oceanographic Office. 1972. En- Puerto Rico and Hispaniola. This work was vironmental Acoustics Atlas of the Caribbean part of the Cooperative Investigation of the Sea and Gulf of Mexico, Volume II. SP- 18911. Caribbean and Adjacent Regions (CICAR). U.S. Navy Hydrographic Office. 1955. Atlas of One of the primary purposes of this phase Pilot Charts: Central American Waters and of the program was to study the exchange South Atlantic Ocean. H. O. Pub. 576. of water between the Atlantic Ocean and the DATE ACCEPTED: January 28, 1977. Caribbean Sea through Mona Passage. The passage is only 380 m deep and thus is of ADDRESSES: (C.P.D. and I.R.D.) Marine Sciences minor importance in the circulation of the Department, University of Puerto Rico, Mayaguez, deeper layers. It is, however, important from Puerto Rico 00708; (D.K.A.) National Oceano- graphic and Atmospheric Administration, Atlantic the standpoint of surface water movements Oceanographic and Meteorological Laboratory, 15 into and out of the Caribbean Sea, inasmuch SHORT PAPERS 587

Table 1. Summary of drift bottle recovery

Launch Recovery

Position Position Ave. Card Date Speed Numbers IX73 (N lat.) (W long.) Date (N lat.) (W long.) Days Km (em/sec)

1 20 18°38' 68°05' 3 X 73 18°23' 68°36' 14 65 5.4 2 20 18°38' 68°05' 24 X 73 18°19' 68°34' 35 74 2.4t 3 20 18°36' 67°53.5' 31 III 74 25°50' 80° 10' 193 3,110 18.7 4 20 18°30.6' 67°26.8' 10 XI 74 24°55' 80°30' 416 3,020 8.4* 5 20 18°30.6' 67°26.8' 27 I 74 20° 15' 87"30' 129 2,220 19.9 6 20 18°29.5' 67° 13' 23 X 73 18°23' 68"33' 34 139 4.7 7 20 18°29.5' 67° 13' lOX 73 18° 19' 68°34' 21 148 8.2t 8 20 18°29.5' 67°13' 6 X 73 18°44' 68°29' 17 130 8.9 9 20 18°29.5' 67°13' 1 XII 73 22"30' 74°00' 73 870 13.8 10 21 18°15.5' 67°37' 2U 74 18°00' 88°20' 134 2,400 20.7 11 21 18° 15.5' 67°37' 16 II 74 20°50' 86°50' 148 2,310 18.1 12 21 18°26' 67°51.5' 16 XI 73 18" 16' 7P03' 57 370 7.5 13 21 18°26' 67°51.5' 15 IV 74 25°40' 80° 12' 206 3,070 17.2* 14 22 18°00.5' 68°13' 28 IV 74 15°50' 88°00' 218 2,330 12.3* 15 23 lr57' 67°25.3' 18 X 73 19° 10' 69°20' 26 278 12.4 16 23 17°57' 67°25.3' 18 X 73 19° 11' 69"20' 26 278 12.4 17 23 18°07.6' 67°56.6' 22 III 74 24°55' 80°30' 180 3,000 19.3 18 23 18°07.6' 67°56.6' 9 XI 73 17°48' 71 ° 18' 47 340 8.3 19 23 18°07.6' 67°56.6' 7 XI 73 17°43' 71 °30' 45 370 9.5 20 23 18°07.6' 67°56.6' 20 III 74 20° 15' 87°30' 178 2,190 14.2* 21 23 18°07.6' 67°56.6' 21 I 74 18°15' 76"50' 120 960 9.3 22 23 18°07.6' 67°56.6' 6X 74 29°00' 80°55' 378 3,520 10.8* 23 23 18°08.3' 67° 50.5' 6 VII 74 28°35' 96°45' 286 3,610 14.6* 24 23 18°02.9' 67°50.3' 4 X 74 17°00' 88° 15' 376 2,330 7.2* 25 23 18°02.8' 67° 55.3' 5 XI 74 18° 10' 7POO' 44 330 8.7 26 23 18°02.8' 6r55.3' 1 II 74 18°00' 88°20' 131 2,400 21.2 27 23 18°02.8' 67° 55.3' 15 II 74 24°31' 82°06' 146* 2,500 19.8* 28 24 17°35.5' 67"00' 17 X 73 18°29' 68°23' 24 185 8.9 29 24 lr35.5' 67°00' 26 X 73 18°09' 68°36' 33 185 6.5 ---- • Heavily faded cards indicating the bottles were stranded on the shore for prolonged periods before discovery, t Recovered at sea. :I: days ±14. This bottle was reported as being retrieved in February 1974, but there was no indication as to the exact date. The speed could thus faU between 18.1 and 2\.9 em/sec. as strong tidal currents are present through- als indicate the number of drift bottles re- out its 115-km width. At the time the work leased at each site. The shaded circles in- was performed, there were plans (since aban- dicate those sites from which returns were doned) for the development of a large oil eventually received. The numbers outside refinery on Mona Island near the middle of the shaded circles are keyed to the recovery the passage, and there was much concern sites in the figures and to the listings in over the effects this might have on the nearby Table 1. Approximately 50 bottles were shores of the to the released at each of four sites closely sur- west (downwind). rounding Mona Island in connection with From the 432 drift bottles released, 29 the oil refinery study mentioned above. A (7%) returns were received. Figure 1 shows hydrographic station was occupied at each the positions of the releases and of the of the release sites except for the four loca- nearby returns. Figure 2 shows the more tions close to the four corners of Mona distant returns. In Fig. 1, the circled numer- Island. 588 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.3, 1971

MONA PASSAGE DRIFT BOTTLE EXPERIMENT SEPT. 1973

DOMINICAN REPUBLIC

Figure 1. Drift bottle launch sites with some of the nearby recovery sites. Circled numerals indicate the number of bottles launched at each site. Shaded circles indicate sites from which recoveries were re- ceived. Numerals outside the circles are keyed in the recovery sites as are shown in this figure and Fig- ure 2 and listed in Tables 1-2.

In Table 1, the date and position of southeast corner of the passage eventually launching, date and position of recovery, moved north through the passage and con- elapsed time between those two dates, the tinued their drift to the northwest on the distance between the launching and recovery Atlantic side of the Antilles. On the other positions, and the calculated speed of the hand, some of those launched in the north- drift are listed for each of the recovered east corner of the passage moved south and drifters. The distances are measured along then drifted west in the Caribbean. The the shortest smooth trajectory between the crossing of the various drift paths is un- launching and recovery sites. The speeds doubtedly the result of the pattern of the were calculated by dividing this distance by tidal and residual currents as the various the elapsed time, in days. It is recognized bottles shifted back and forth in the passage. 1 that this crude system yields gross underesti- mations of both distances and speeds. Although it is conceivable that those The tidal currents in Mona Passage are bottles retrieved along the east coast of pronounced, highly variable, and poorly 1A verbal report from a Puerto Rican sport fisherman understood. As is shown schematically in who ran out of fuel in Mona Passage told of being swept past Mona Island 3 or 4 times in a couple of days before Fig. 1, some of the bottles launched in the being rescued. SHORT PAPERS 589

12 ~ 25 18 19

Figure 2. Recovery sites of drift bottles recovered olltside the immediate launch area in Mona Passage. The numbered sites are keyed to the launch positions in Figure 1 and to the information listed in Tables 1-2.

Florida arrived there by drifting north of from Mona Island launch sites stranded the Antilles, it is considered to be much further along the south coast about 320-340 more likely that they drifted through the km from the launch sites. Caribbean Sea and then through the Yucatan No bottles were retrieved from any loca- Channel into the Gulf of Mexico and out tions east of their launching sites. This is of through the Florida Straits. This is sup- interest inasmuch as fairly strong though ported by the number of returns from the intermittent eastward flowing surface cur- Yucatan coast and one from the northwest- rents have been observed all along the north ern corner of the Gulf of Mexico. coast of Puerto Rico inshore of the normal With regard to the question of the route westward surface drift of that region (Puerto which might be taken by oil spills and general Rico Aqueduct and Sewer Authority, 1975). flotsam from a possible refinery on Mona The major difficulty in trying to determine Island, it is interesting that none of the the speed of a current from drift bottle obser- bottles launched in the immediate vicinity vations, beside the problem of estimating the of the island came ashore on the eastern end true trajectory of the drift, is the uncertainty of the Dominican Republic. However, eight as to the length of time the bottle was bottles from other launch sites within the stranded. With regard to this and other passage did land there, and three bottles factors leading to uncertainty as to the true 590 BULLETIN OF MARINE SCIENCE, VOL. 27, NO.3, 1977

Table 2. Comparison of calculated speeds of short and long drift groups

Long Drift Period Short Drift Period Less Faded Cards Heavily Faded Cards' No. Km em/sec No. Km em/sec No. Km em/sec

1 65 5.4 3 3,110 18.7 4 3,020 8.4 2 74 2.4 5 2,220 19.9 13 3,070 17.2 6 139 4.7 10 2,400 20.7 14 2,330 12.3 7 148 8.2 11 2,310 18.1 20 2,190 14.2 8 130 8.9 17 3,000 19.3 22 3,520 10.8 9 870 13.8 26 2,400 21.2 23 3,610 14.6 12 370 7.5 24 2,330 7.2 15 278 12.4 27 2,500 19.8 16 278 12.4 18 340 8.3 19 370 9.5 21 960 9.3 25 330 8.7 28 185 8.9 29 185 6.5 Average 8.5 em/sec Average 19.6 em/sec Average 13.1 em/sec (7.3 km/day) (17.0 km/day) (11.3 km/day) • The heavily faded cards indicate the bottles were stranded on the shore for prolonged periods before discovery. speed of the current, it is a safe rule that the em/sec (11.3 km/day) while the less faded higher the calculated speeds, the more re- group of six cards showed a speed of 19.6 alistic they are, and even then they are em/sec (17.0 km/day). The difference was generally underestimates. unquestionably due to the fact that the In this experiment, the retrievals fell into faded group spent more time on the beach two major classes which are apparent in the before discovery than did the unfaded group. Figures and in Table 1. Approximately half Obviously, the higher speed is nearer to the the recovered bottles travelled less than true speed of the drift than is the lower one. 1,000 km, and the other half travelled more The difference between the calculated than 2,000 km. None was retrieved in any speeds of the long and short drift groups is area in between. As is shown in Table 2, attributed to the magnified effect that the the average calculated speed of the shorter two major factors described above have on distance group was 8.5 em/sec (7.3 km/day) the shorter drifts: (1) The shorter drift and the maximum speed was 13.8 em/sec. group spent a higher percentage of their The longer distance group went considerably total time between launch and discovery in faster. the back~and-forth tidal currents within In the long distance group, eight out of the Mona Passage, (2) The time stranded repre- 14 returns showed very pronounced fading sents a larger percentage of the total time in of the bright orange "day-glow" cards while the case of a short drift than in that of a long the remaining six showed much less fading. one. Very little fading takes place while the bottle For all the inherent weakness in any at- is drifting mostly submerged and in a vertical tempt to determine current speeds from drift position. When the bottle strands and comes bottle experiments, it is felt that the present to rest on its side on the shore, the card is study has produced some interesting results. much more exposed to direct sunlight and In summary, it showed that all the retrieved fades rapidly. The eight most faded cards drifters without exception moved to the west. showed an average calculated speed of 13.1 The complex pattern of the flow in Mona SHORT PAPERS 591

Passage itself is attested to both by the THE SIGNIFICANCE OF ZOOXAN- slowness of the net drift and by the fact that THELLA-CONTAINING PELLETS EX- some of the bottles launched at the southern TRUDED BY SEA ANEMONES end of the passage eventually drifted into the Atlantic, and some of those launched at R. D. Steele the northern end eventually drifted into the Caribbean. There is a very real danger that ABSTRACT-A number of sea anemones normally surface pollutants from the Mona Passage release pellets containing zooxanthellae in various area would drift ashore on the Dominican stages of the life history. All stages are not al- Republic. Most of the drifters launched ways present at the same time. Most contain throughout the Mona Passage area which ciliates which ingest the zooxanthellae and other drifted beyond the Dominican Republic did microscopic invertebrates are often present. so on the Caribbean side of the Antilles. The In these anemones, ejected zooxanthella-contain- ing pellets represent the pathway through which drift across the Caribbean takes place at either excess symbionts are discarded or broken speeds greater than 20 em/sec, but how down zooxanthella material is voided. much greater cannot be determined. Evidence obtained from some species indicates that the zooxanthella life history may include a ACKNOWLEDGMENTS step in which zoospore formation follows cell divi- The field work carried out on CRAWFORD sion and that this only occurs in extruded pellets. Cruise #73-24 was supported by the National In addition, since motile zoospores are present in Oceanographic Data Center under Project 35207 pellets for up to five days after collection, then with the University of Puerto Rico with funds it seems almost certain that the zoospore is the provided by the International Decade of Ocean- dispersal phase of the zooxanthella. ographic Exploration (IDOE) section of the Differences between zoospores from different National Science Foundation. The data were gathered together and analyzed at the Woods Hole anemones with respect to color and morphology Oceanographic Institution with NSF support under have been observed and to date two types of Contract OCE 75-19729. This support is gratefully zoospore can be regularly recognized. acknowledged. Thanks are due to the finders of the drift bottles who took the trouble to' supply the information as to the date and location of the re- All stages in the life history of the zooxan- coveries. This is contribution No. 3818 from the thelia symbiotic with the sea anemone Aip- Woods Hole Oceanographic Institution. tasia tagetes (Duch. and Mich.) have been LITERATURE CiTED observed in dark brown pellets normally ex- Bumpus, D. F. and L. M. Lauzier. 1965. Serial truded by the host. These pellets consist atlas of the marine environment. Folio 7, almost exclusively of algal cells held together Am. Geog. Soc., 7 pp, 8 pIs. by mucus and are distinct from fecal pellets Puerto Rico Aqueduct and Sewer Authority. (Steele, 1975). 1975. Barceloneta, Puerto Rico, Oceano- graphic Baseline Study. Vol. 1, Final Report, Subsequent observations made on zooxan- prepared by Black and Veatch, and Rafael A. thelIa-containing anemones reveal that Domenech and Associates, Consulting Engi- healthy and degenerate cysts, dividing cysts, neers. Chapter 7, pp. 12-15. zoosporangia, and zoospores are present in DATE ACCEPTED: January 28, 1977. similar pellets released by a number of these species (Table 1). However, all algal forms ADDRESSES: (W.G.M. and M.C.S.) Woods Hole Oceanographic Institution, Woods Hole, Massa- are not always present in the pellet at the c1lllsetts 02543; (D.K.A.) Department of Marine same time. Sciences, University of Puerto Rico, Mayaguez, In the two species, Phyllactis flosculifera Puerto Rico 00708. PRESENT ADDRESS: National (Lesueur) and Stoichactis helianthus (Ellis), Oceanographic and Atmospheric Administration, dark brown pellets are extruded which con- Atlantic Oceanographic alld Meteorological Labo- ratory, 15 Rickenbacker Causeway, Miami, Florida sist mainly of algal debris held together by 33149. mucus. However, a very small number of