Changes in gametogenesis and fecundity of acroporid corals that were exposed to elevated nitrogen and phosphorus during the ENCORE experiment

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1 L Journl of Experimentl Mrine Biology nd Ecology 246 (2000) locte/ jembe Chnges in gmetogenesis nd fecundity of croporid corls tht were exposed to elevted nitrogen nd phosphorus during the ENCORE experiment * Selin Wrd, Peter Hrrison Centre for Costl Mngement, Southern Cross University, Lismore NSW, Austrli Received 24 April 1999; received in revised form 3 September 1999; ccepted 7 December 1999 Abstrct Colonies of two sclerctinin reef corl species, Acropor longicythus nd Acropor sper were trnsplnted into ptch reefs t One Tree Reef, Gret Brrier Reef, Austrli s prt of the ENCORE experiment. These corls nd colonies of A. sper which were nturlly present in the ptch reefs were exposed to four tretments over two yers: controls with norml sewter, elevted levels of nitrogen only, phosphorus only, or nitrogen plus phosphorus. These corls were smpled nd used to determine whether gmetogenic cycles nd fecundity were ffected by nutrient enrichment. Acropor longicythus hd single nnul gmetogenic cycle. Corls exposed to elevted nitrogen produced significntly smller nd fewer eggs nd contined less testes mteril thn those which were not exposed to nitrogen. Exposure to elevted phosphorus only resulted in corls producing more but smller eggs, nd more testes mteril. Egg numbers of colonies from other tretments decresed s the gmetogenic cycles continued, but those of the phosphorus colonies showed lmost no reduction in egg numbers between the erly nd lte stges of the gmetogenic cycles. These results hve importnt mngement implictions for corl reefs s they demonstrte tht smll increses in concentrtions of nitrogen nd phosphorus cn hve severe effects on reproductive ctivity in these species of sclerctinin corls Elsevier Science B.V. All rights reserved. Keywords: Corl; Reproduction; Nutrients; ENCORE; Fecundity 1. Introduction Corl reefs typiclly flourish in nutrient poor tropicl ses (Drwin, 1842; Odum nd *Corresponding uthor. Present ddress: Centre for Mrine Studies, The University of Queenslnd, Austrli. E-mil ddress: selinwrd@bigpond.com (S. Wrd) / 00/ $ see front mtter 2000 Elsevier Science B.V. All rights reserved. PII: S (99)

2 180 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Odum, 1955), lthough they lso occur in wide rnge of nutrient concentrtions (Kinsey, 1979; Kinsey nd Dvies, 1979; Smith et l. 1981). Nutrient levels in wters round corl reefs rnge from 0 to 4 (mm nitrogen nd (mm phosphorus (Kinsey, 1988; D Eli nd Wiebe, 1990), however nutrient concentrtions on corl reefs re usully n order of mgnitude lower thn those of shllow wter temperte ecosystems. Eutrophiction cuses significnt problems for corl reefs, nd cn result in degrdtion of reef ecosystems (e.g. Bnner, 1974; Smith et l., 1981; Pstorok nd Bilyrd, 1985; Tomscik nd Snder, 1985; Bell, 1992,b). Nutrient enrichment cn led to enhnced growth of phytoplnkton nd ttched lge (Pstorok nd Bilyrd, 1985; Schffelke nd Klumpp, 1998), chnges in the composition of lgl, corl nd other benthic communities (Bnner, 1974; Wlker nd Ormond, 1982; Nim, 1993), nd deteriortion in wter qulity (Brodie, 1992). Elevted levels of nutrients cn reduce the rte of growth nd clcifiction of corls, nd reef clcifiction (Kinsey nd Dvies, 1979; Wlker nd Ormond, 1982; Dubinsky nd Jokiel, 1994) but Atkinson et l. (1995) found no reduction in growth rtes of corls exposed to high nutrient levels in quri. Field studies long grdient of eutrophiction nd other pollution in Brbdos, West Indies, showed tht plnul production by the brooding reef corl Porites porites ws reduced in polluted res (Tomscik nd Snder, 1987), nd the bundnce nd diversity of corl recruits decresed with incresing eutrophiction (Tomscik, 1991; Hunte nd Wittenberg, 1992). A number of nthropogenic ctivities increse nutrient lodings in mrine environments, including runoff from griculturl nd urbn res (Bell, 1992b; Brodie, 1992) nd deforesttion in ctchments (Webb, 1984; Kuhlmnn, 1988; Brodie, 1992; Byron nd Brodie, 1992). One of the most importnt nthropogenic sources of nitrogen nd phosphorus to mrine environments is sewge, nd this cn be mjor problem for corl reefs (e.g. Doty, 1969; Bnner, 1974; Kinsey, 1979; Mrszlek, 1981; Smith et l., 1981; Wlker nd Ormond, 1982; Pstorok nd Bilyrd, 1985; Grigg, 1995). Phosphorus is found in both humn wste nd phosphorus bsed detergents, nd in Austrli tonnes of phosphorus nd tonnes of nitrogen re produced in sewerge effluent nnully (Brodie, 1992). The ENCORE (Elevted Nutrients on Corl Reefs Experiment) experiment ws conducted in order to better understnd the effects of elevted levels of nitrogen nd phosphorus on corl reefs. ENCORE ws lrge scle mnipultive reef fertiliztion experiment designed to quntify the fte of nitrogen nd phosphorus within corl reef nd to ssess their reltive impct on vriety of corl reef orgnisms (Steven nd Lrkum, 1993; Lrkum nd Steven, 1994). An importnt difference between the ENCORE experiment nd previous work on nutrients is tht ENCORE concentrted on exmining effects of nitrogen nd phosphorus in isoltion, rther thn in conjunction with other confounding fctors such s sediment, hevy metls nd other toxins tht re often ssocited with nutrient enrichment in eutrophic res. Thus, differences between tretments in ENCORE cn be directly ttributed to the effects of the nutrients. Sclerctinin corls hve similr pttern of gmetogenesis to tht of other cnidrins (Giese nd Perse, 1974), nd either brodcst spwn gmetes for externl fertiliztion nd development or brood lrve within polyps, nd my be hermphroditic or

3 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) gonochoric (Fdlllh, 1983; Hrrison nd Wllce, 1990). In hermphroditic corl species, eggs nd spermries my develop on the sme mesenteries (s in the fviids nd mussids), on different mesenteries within the sme polyp (most pocilloporids nd croporids), in different polyps within the sme colony, or rrely, t different times within the sme colony (Fdlllh, 1983; Hrrison nd Wllce, 1990). Acroporids re hermphroditic with eggs nd spermries on different mesenteries within the sme polyp. Mesures of fecundity such s the number of eggs or the number of plnule per polyp cn provide useful index of reproductive effort nd, s such, re useful indictor of the helth of corl (Kojis nd Quinn, 1984; Hrrison nd Wllce, 1990). Consequently, chnges in these mesures cn be n indiction of sublethl stress in corls. However, fecundity lone cn underestimte the reproductive effort of the corl nd is better combined with other reproductive mesures such s the size of the eggs nd the volume of testes mteril (Hrrison nd Wllce, 1990). It is importnt to understnd the gmetogenic cycle of the species so tht smpling cn occur t the most pproprite times. The ims of these experiments were to exmine the potentil effects of elevted levels of nutrients on gmetogenesis nd fecundity in two reef corl species, Acropor longicythus nd Acropor sper, trnsplnted into the experimentl microtolls. Secondly, fecundity in colonies of Acropor sper occurring nturlly in the microtolls ws quntified to determine whether these were ffected by the nutrient tretments. These species were chosen s they hve reltively lrge polyps tht cn be dissected by hnd so tht the eggs nd testes my be mesured without the use of histologicl sections (Oliver, 1979; Wllce, 1985). When mesuring reproductive output it is preferble to use polyp dissections rther thn histology, s tissue shrinkge occurs during histologicl processes, nd gmetes or lrve my not occur in some sections, hence reproductive output my be underestimted in histologicl sections (Hrrison nd Wllce, 1990). A. longicythus is lso very suitble for trnsplnttion becuse s the colonies grow, the bsl res die off, so tht individul sections of one or more brnches usully ttch directly onto the substrtum so sections of the colonies cn be removed without dmging the reminder of the colony. The bottlebrush growth form lso llows esy frgmenttion. 2. Methods One Tree Reef is locted in the Mcky Cpricorn section t the southern end of the Gret Brrier Reef Mrine Prk ( E, S) nd is situted 70 km est of Gldstone on the cost of Queenslnd nd 18 km from the edge of the continentl shelf. One Tree Reef is pltform reef which mesures km nd contins three seprte lgoons (Hetwole, 1981). The unbroken emergent reef crest cuses the min lgoon t One Tree Reef to be isolted from the surrounding wter t low tide once the outside tide flls below bout men surfce wter level (generlly for 5 6 h) (Htcher nd Frith, 1985). This restricts the time vilble for wter exchnge between the lgoon nd the ocen to hlf the tidl cycle. The lgoon hs complex structure with numerous

4 182 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) smll circulr ptch reefs termed microtolls. At low tide, wter within these microtolls is isolted from the surrounding lgoonl wter for 3 4 h nd during high tide the wter rises 0.1 up to 1.2 m bove the perimeter. The microtolls hve wlls mde of corlline lge nd corl nd these wlls drop verticlly to the lgoon floor which is usully 5 8 m depth Experimentl design Twelve microtolls in the northern end of the lgoon were chosen for the ENCORE 3 experiment. These mesured m cross, hd volumes of m nd hd similr corl/ lgl communities (Lrkum nd Steven, 1994). Three microtolls were rndomly llocted to one of four tretments. Three microtolls were given no dditionl nutrients (controls), three microtolls were dosed with mmonium chloride only (nitrogen tretment), three were dosed with potssium dihydrogen phosphte (phosphorus tretment) nd three microtolls were dosed with combintion of nitrogen nd phosphorus (mmonium chloride plus potssium dihydrogen phosphte) Acropor longicythus Acropor longicythus ws chosen s the min experimentl species nd, consequently, its gmetogenesis ws studied in the most detil. Sixty lrge colonies of Acropor longicythus were selected within the lgoon. These colonies were locted in the lgoon, round the outside of the ENCORE microtolls nd nerby ptch reefs in wter no more thn 2 m deep. In n ttempt to void choosing clone colonies, most colonies were t lest 10 m from ech other nd were selected on the bsis of hving different growth forms nd pigmenttion. Severl lrge pieces were tken from ech prent colony nd these were trnsplnted from the lgoon into the twelve ENCORE microtolls in Februry 1993, seven months before the nutrient dosing commenced. Five colonies were rndomly chosen from the sixty prents to be trnsplnted to ech of the 12 microtolls so tht there ws totl of 15 A. longicythus trnsplnts for ech tretment (i.e. five colonies in three microtolls per tretment). The pieces of ech colony were trnsplnted onto seprte plstic rck with PVC legs to hold it bove the substrtum. Pieces of corl were ttched to the rcks using cble ties nd the rcks were plced on the substrtum of the microtolls. The prentl colonies from which the trnsplnts were tken were lbelled so tht they could be smpled throughout the study. They received no dditionl nutrients or mnipultion Acropor sper Portions of five colonies of Acropor sper were lso trnsplnted into the microtolls. This species forms very lrge colonies nd the five prent colonies which were chosen were lrge, situted t lest 50 m prt nd were different colours. One piece of ech of these prent colonies ws trnsplnted into ech of the 12 microtolls, which provided 15 trnsplnts for ech tretment (i.e. five colonies in three microtolls

5 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) per tretment). Trnsplnted pieces were ttched to plstic rcks nd plced into the microtolls in the sme mnner s those of Acropor longicythus. The five A. sper prent colonies were not monitored Non-trnsplnted A. sper In ddition, colonies of Acropor sper were lredy growing nturlly in nine of the microtolls nd 18 of these nturlly occurring colonies were lbelled nd mpped for smpling. There were two fertiliztion periods; the initil dosing commenced in September 1993 nd continued until Jnury Microtolls were dosed twice dy, once every low tide when the microtolls were isolted from the surrounding lgoon. Nutrients were dded to chieve concentrtions within the microtolls of 10 mm nitrogen nd 2 mm phosphorus t the strt of ech fertiliztion. The nutrients were rpidly dispersed within the microtolls so tht nutrient concentrtions were 2 mm mmonium nd 0.2 mm phosphorus within minutes following ddition, nd were close to bckground levels within 1 3 hours fter dosing (K. Koop, pers. comm.). The rte of nutrient dissiption ws influenced by wether conditions with concentrtions dropping fstest on windy dys. During the second fertiliztion phse, from Jnury 1995 to Februry 1996, concentrtions were incresed to chieve lodings of 20 mm mmonium nd 4 mm phosphorus. Microtolls were dosed three times every low tide rther thn once to ensure more constnt concentrtion. Actul concentrtions of nutrients during the low tides in this period were much closer to the intended concentrtions thn those chieved in the first period of fertiliztion. Concentrtions of pproximtely 20 mm mmonium nd 4 mm phosphorus were mintined for much of the low tide period. Over the 430 dys of fertiliztion totl loding of the microtolls rnged between 2097 nd 5977 moles of NH 4 N nd 245 to 1380 moles PO 4 P. The lower figures for ech represent lodings between the low tide dosing periods. This experiment used short term pulsed dditions which resulted in comprtively smll increses in nutrient vilbility Smpling procedure The 60 Acropor longicythus trnsplnts nd 60 prentl colonies were smpled t pproximtely three monthly intervls from Februry 1993 to November Sixty Acropor sper trnsplnts were smpled pproximtely one month before spwning nd few dys prior to the predicted spwning period ech yer. The 18 colonies of A. sper nturlly occurring in the microtolls were smpled few dys before the predicted spwning period ech yer. For ll groups of corls, pieces of corl brnches between 7 nd 10 cm long were broken from the colonies using long nosed pliers nd plced into 10% formldehyde in sewter. In the lbortory these pieces were declcified using M hydrochloric cid nd 2% formldehyde. Declcifiction took 1 2 weeks nd generlly required one chnge of cid. The declcifiction process ws continued until no skeletl mteril remined. Smples were then plced into 70% lcohol in plstic vils.

6 184 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Processing of smples Five polyps were scored for ech smple. Individul polyps were dissected out from the declcified tissue while viewed under stereo dissecting microscope (fter Oliver, 1979; Wllce, 1985). Ech polyp ws dissected to expose the eight mesenteries. Four mesenteries contined strings of eggs nd four mesenteries developed testes. For ech polyp, the number nd the size of the eggs were scored. Two mesurements were tken from ech egg, length nd width mesurement using clibrted eyepiece micrometer in the dissecting microscope. The egg size ws the men of these two mesures. The egg size of the polyp ws the men of the individul egg sizes. Egg totl ws clculted by dding ll the individul egg sizes (or by multiplying the polyp egg size by the polyp egg number). Testes were counted for the testes number. The length nd width of ech testis ws mesured using clibrted eyepiece micrometer. The length nd width of ech testis were multiplied together nd the sum of these clcultions for ech polyp ws clled the testes totl for tht polyp Sttisticl nlyses The egg number, polyp egg size, egg totl nd testes totl were nlysed for Acropor longicythus nd Acropor sper trnsplnts using orthogonl two wy nested nlyses of vrince (Underwood, 1981). The min fctors were the presence or bsence of nitrogen nd the presence or bsence of phosphorus. For the nitrogen nlyses, microtolls exposed to elevted nitrogen (nitrogen only nd nitrogen plus phosphorus microtolls) were compred with those which did not receive nitrogen (controls nd phosphorus only microtolls). For the phosphorus nlyses, microtolls exposed to phosphorus (phosphorus only nd nitrogen plus phosphorus microtolls) were compred with those which did not receive phosphorus (controls nd nitrogen only). Microtolls were nested within the nitrogen by phosphorus interction. Heterogeneity of vrince ws tested using Cochrn s test. The dt for the colonies of Acropor sper nturlly occurring in the microtolls were nlysed using two wy orthogonl nlyses of vrince without the microtoll nesting s these colonies were only present in nine of the twelve microtolls. Fecundities of trnsplnted colonies of Acropor longicythus in ech tretment were compred with those of their prentl colonies using one wy nlyses of vrince. 3. Results 3.1. Acropor longicythus trnsplnts Elevted nutrients ffected the polyp fecundity of Acropor longicythus trnsplnts in the experimentl microtolls. The nitrogen tretments (nitrogen lone nd nitrogen plus phosphorus) tended to reduce the number nd size of eggs per polyp nd the testes

7 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) totl (Figs. 1 7). Phosphorus lone hd different effect reflected in the mny significnt nitrogen by phosphorus interctions found in the nlyses of vrince. Phosphorus generlly reduced the size of the eggs but often cused n increse in the number of eggs per polyp (Tbles 1 7). For this reson the results for the phosphorus only corls will be described seprtely. Fig. 1. The men number of eggs present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from November 1993 to November Error brs re stndrd errors.

8 186 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 2. The men size of eggs (mm) present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from November 1993 to November Error brs re stndrd errors Phosphorus only The men number of eggs per polyp ws elevted in the phosphorus only microtolls compred with other tretments on most smpling dtes towrds the end of the gmetogenic cycles. The trnsplnts from the controls, nitrogen nd nitrogen plus phosphorus showed reduction in the number of eggs per polyp present during the gmetogenic cycle, so tht the number of eggs per polyp present in Februry nd My

9 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 3. The men egg totl (egg size3egg number) present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from November 1993 to November Error brs re stndrd errors. ws greter thn the number in November (Fig. 5). In contrst, the corls exposed to elevted phosphorus only retined lmost ll of the eggs present erly in the cycle until the spwning period. Erly in the cycle there were no significnt differences between egg numbers of the phosphorus only corls nd the other tretments (Februry 1995, My 1995) (Tbles 4 5) but by August nd November, when corls from the other tretments hd reduced men egg numbers per polyp, there were significntly more eggs in the phosphorus corls thn those in the other tretments (November 1993, 1994, 1995, August 1995) (Tbles 1, 3, 6, 7; Figs. 1, 5).

10 188 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 4. The men testes totl present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from November 1993 to November Error brs re stndrd errors. In contrst, phosphorus significntly reduced the size of the eggs in November 1993 nd November 1994 (Tbles 1, 3; Fig. 2) with men egg size of 359 mm in November 1993 compred with 382 mm in the control colonies. Phosphorus lone significntly incresed the egg totl on some dtes (November 1993, 1994, 1995) (Tbles 1, 3, 7; Figs. 3, 7). There ws more testes mteril present in corls exposed to elevted phosphorus only compred with other tretments, nd this ws most pronounced in November 1994 when the testes totl for these corls ws 2100 compred to 1339 in the controls. The testes totl ws significntly incresed in the phosphorus only microtolls in November 1994 nd 1995 but not in November 1993 (Tbles 1, 3, 7; Fig. 4).

11 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 5. The men number of eggs present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from Februry 1995 to November Error brs re stndrd errors Nitrogen The effects of the presence of elevted nitrogen on the fecundity of Acropor longicythus were less obvious but the direction of effect of both nitrogen nd nitrogen

12 190 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 6. The men size of eggs (mm) present in polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from Februry 1995 to November Error brs re stndrd errors. plus phosphorus tretments ws the sme. The men number of eggs per polyp in the nitrogen tretments ws reduced on some dtes but not others. The egg number ws significntly reduced in corls exposed to nitrogen compred with those not exposed to nitrogen in November 1993 (Tble 1, Fig. 1) nd June 1994 (Tble 2, Fig. 1). However,

13 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 7. The men egg totl (egg number3egg size) of polyps of Acropor longicythus trnsplnts from the experimentl microtolls t One Tree Reef from Februry 1995 to November Error brs re stndrd errors. by November 1994 the nitrogen only tretment colonies hd resorbed fewer eggs thn the control colonies resulting in similr men number of eggs per polyp mong these tretments.

14 192 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 1 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in November 1993 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P, Egg totl Nitrogen , Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Testes totl Nitrogen , Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. Smller eggs were found in the nitrogen tretments thn in the non-nitrogen tretments nd this effect ws most pronounced in the corls exposed to nitrogen only (e.g. men egg size of 302 mm compred to 338 mm in controls in November 1995). Egg size ws significntly reduced by elevted nitrogen compred to tretments without

15 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 2 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in June 1994 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos Microtoll within N3P Totl C , P, Egg size Nitrogen Phosphorus , Nit. by phos Microtoll within N3P Totl C , P Egg totl Nitrogen , Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. elevted nitrogen (November 1993, 1994, 1995, My 1995, August 1995) (Tbles 1 7; Figs. 2, 7). Egg totl ws lso reduced by the presence of elevted nitrogen in November 1993, June 1994, November 1994 nd November 1995 (Tbles 1,2,3,7; Figs. 3, 7). Exposure to elevted nitrogen reduced the mount of testes mteril produced with the nitrogen only corls hving men vlues of lmost double those of the nitrogen plus phosphorus corls in November The testes totl ws significntly reduced by exposure to nitrogen in November 1993 nd 1995 (Tbles 1, 7). In November 1995 the nitrogen nd nitrogen plus phosphorus tretments hd men testes totl vlues pproximtely two thirds those of the control colonies Acropor longicythus: comprison of trnsplnts nd prentl colonies Comprisons of mesures of fecundity between trnsplnted corls nd their prentl

16 194 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 3 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in November 1994 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Egg totl Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Testes totl Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Testes volume dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. colonies provide informtion bout the effects of trnsplnttion to shllower wter nd the effects of nutrients. Trnsplnted corls tended to produce smller eggs thn their prentl colonies (Fig. 9), but generlly the differences between trnsplnted corls nd their prents were most pronounced when there ws lso difference between the trnsplnt tretment nd the other tretments. For exmple, if there were more eggs in

17 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 4 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in Februry 1995 df SS MS F P Egg number Nitrogen Phosphorus Nit. by Phos Microtoll within N3P Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Egg totl Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Two wy orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. the colonies exposed to phosphorus only on certin dte, there would be more eggs in those trnsplnts thn their prentl colonies on tht dte (Figs. 8 11). There were no significnt differences between the number of eggs per polyp in the control colonies nd their prentl colonies between November 1993 nd 1995 (ANOVA 1993: df5139, F , P : df5130, F , P : df5145, F , P ) (Fig. 8). Although there were significntly fewer eggs per polyp in the nitrogen trnsplnts thn the other tretments in November 1993, there ws no significnt difference between the number of eggs in these corls nd their prentl colonies on this dte or in November 1994 (ANOVA 1993: df5149, F , P : df5140, F , P In contrst, there were significntly more eggs per polyp in the nitrogen only trnsplnts thn their prents in November 1995 (ANOVA df5149, F , P ). Reflecting the difference between nutrient tretments, there were significntly more eggs in the phosphorus only trnsplnts thn their prentl colonies in 1993, 1994 nd

18 196 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 5 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in My 1995 df SS MS F P Egg number Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P, Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P, Egg totl Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P, Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue (e.g. ANOVA 1993: df5150, F , P,0.0001) nd fewer eggs in the nitrogen plus phosphorus corls thn their prentl colonies in 1993 nd 1994 (e.g. ANOVA 1993: df5149, F , P ). The size of the eggs of trnsplnted colonies ws generlly significntly smller thn those of the prentl colonies (Fig. 9). The only exceptions were the control corls in November 1993 (ANOVA df5112, F , P ) nd November 1995 (ANOVA df5146, F , P ) nd the nitrogen plus phosphorus corls in November 1993 (ANOVA df5122, F , P ). The egg totl of the prentl colonies generlly mirrored the trnsplnts except where there ws difference due to tretment (e.g. ANOVA 1993 phosphorus: df5150, F , P ; ANOVA 1994 nitrogen plus phosphorus: df5149, F , P ).

19 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 6 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in August 1995 df SS MS F P Egg number Nitrogen Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Egg totl Nitrogen Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. A regulr pttern ws not obvious for the testes totl of the trnsplnts nd prentl colonies. In November 1993, only the nitrogen plus phosphorus corls hd significntly lower testes totl thn tht of the prentl colonies (ANOVA df5149, F , P ). In November 1994 nd 1995 the phosphorus trnsplnt colonies hd significntly greter testes totls thn those of the prentl colonies nd this reflects the tretment differences (Fig. 11) (ANOVA 1994: df5147, F , P : df5144, F , P,0.0001). The control trnsplnt colonies hd smller testes thn their prentl colonies in November 1994 (ANOVA df5130, F , P ) but lrger testes in November 1995 (ANOVA df5145, F , P ) Acropor sper trnsplnts There were some Acropor sper trnsplnts tht hd no eggs or testes in their

20 198 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 7 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor longicythus trnsplnts in the experimentl microtolls t One Tree Reef in November 1995 df SS MS F P Egg number Nitrogen , Phosphorus , Nit. by phos , Microtoll within N3P , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Egg totl Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Testes totl Nitrogen , Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. smple brnches. This ws due to colonies hving either no gmetes in the prticulr brnch which ws smpled or hving no gmetes in the entire colony. Due to this lck of gmetes in some of the November 1993 nd prticulrly 1994 smples, the smple sizes were smller thn for the other dtes. The men number of eggs per polyp in the A. sper trnsplnts ws considerbly lower thn those in the Acropor longicythus

21 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 8. The number of eggs present in the colonies of Acropor longicythus trnsplnted to the experimentl microtolls t One Tree Reef. These re represented by the blnk brs. The shded brs represent the number of eggs present in the prentl colonies of the trnsplnts which hve remined in the lgoon t One Tree Reef. Error brs re stndrd errors. colonies with the November 1993 tretment mens rnging from 6.99 to 8.40 eggs per polyp in A. sper compred with up to 20 eggs per polyp in A. longicythus. The men number of eggs present ws prticulrly low in November 1994 for A. sper with mens of 0.4 to 5 per polyp (Fig. 12). Eggs mesured in the November 1993 smples

22 200 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 9. The size of eggs (mm) present in the colonies of Acropor longicythus trnsplnted to the experimentl microtolls t One Tree Reef. These re represented by the blnk brs. The shded brs represent the number of eggs present in the prentl colonies of the trnsplnts which hve remined in the lgoon t One Tree Reef. Error brs re stndrd errors. were bigger thn those from 1994 or 1995 (Fig. 13). The men egg size for ll A. sper trnsplnts for November 1993 ws 425 mm compred with 321 mm in November The trends found in the fecundity of Acropor longicythus colonies were lso pprent for the A. sper colonies (Figs ). In November 1993, the men egg number per polyp ws higher in the nitrogen plus phosphorus microtolls thn in the other tretments but this pttern ws not found on other smpling dtes. In contrst,

23 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 10. The egg totl (egg size3egg number) present in the colonies of Acropor longicythus trnsplnted to the experimentl microtolls t One Tree Reef. These re represented by the blnk brs. The shded brs represent the number of eggs present in the prentl colonies of the trnsplnts which hve remined in the lgoon t One Tree Reef. Error brs re stndrd errors. significntly fewer eggs per polyp were found in the nitrogen plus phosphorus tretment thn in other tretments in November 1994 (Tble 8, Fig. 12). In October 1994, November 1994 nd November 1995 there were significntly more eggs per polyp in the phosphorus lone tretment thn in the other tretments (Fig. 12). Eggs were significntly smller in the phosphorus tretments (phosphorus lone nd nitrogen plus phosphorus) compred with the non-phosphorus tretments in October 1994 (Tble 9, Fig. 13). In November 1995 the eggs were smller in the nitrogen thn in

24 202 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 11. The testes totl present in the colonies of Acropor longicythus trnsplnted to the experimentl microtolls t One Tree Reef. These re represented by the blnk brs. The shded brs represent the number of eggs present in the prentl colonies of the trnsplnts which hve remined in the lgoon t One Tree Reef. Error brs re stndrd errors. the non-nitrogen tretments nd in the phosphorus thn in the non-phosphorus tretments (Tble 9, Fig. 13). In November 1994 the eggs were lrger in the nitrogen plus phosphorus tretments thn the other tretments. Egg totl ws much lrger in November 1993 thn on the other smpling dtes. The egg totl in the nitrogen plus phosphorus tretment ws significntly reduced in November 1994 nd 1995 but ws elevted in November Egg totl ws elevted in

25 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 12. The men number of eggs present in polyps from colonies of Acropor sper which were trnsplnted into the experimentl microtolls t One Tree Reef, during the period from November 1993 to November Error brs re stndrd errors. the phosphorus only microtolls compred with the other tretments in October 1994, November 1994 nd November 1995 (Tbles 8 10; Fig. 14). Testes totls vried gret del with both dte nd tretment. The testes totl ws considerbly lrger in November 1993 thn on other smpling dtes with the men for

26 204 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 13. The men size of eggs (mm) present in polyps from colonies of Acropor sper which were trnsplnted into the experimentl microtolls t One Tree Reef, during the period from November 1993 to November Error brs re stndrd errors. ll the trnsplnts in November 1993 four times greter thn tht for November Testes totls were prticulrly vrible in November 1994 with tretment men for the nitrogen plus phosphorus microtolls less thn one sixth tht of the phosphorus only microtolls. There were greter testes totls present in the phosphorus only tretment

27 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 14. The men egg totl (egg number3egg size) present in polyps from colonies of Acropor sper which were trnsplnted into the experimentl microtolls t One Tree Reef, during the period from November 1993 to November Error brs re stndrd errors. compred to other tretments on October 1994, November 1994 nd November 1995 (Tbles 8 10; Fig. 15). The testes totls were drmticlly reduced in the nitrogen plus phosphorus microtolls in October nd November 1994 nd November nd in the nitrogen only tretment in November 1995.

28 206 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Fig. 15. The men testes totl present in polyps from colonies of Acropor sper which were trnsplnted into the experimentl microtolls t One Tree Reef, during the period from November 1993 to November Error brs re stndrd errors Acropor sper occurring nturlly in the microtolls The Acropor sper growing nturlly in the microtolls hd higher fecundity thn the A. sper trnsplnts. The men number of eggs per polyp in the colonies of

29 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 8 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor sper trnsplnts in the experimentl microtolls t One Tree Reef in November 1993 df SS MS F P Egg number Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P, Egg totl Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Testes totl Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. Acropor sper occurring nturlly in the microtolls ws greter in the controls in November 1994 (10.9 compred with 1.77 for the trnsplnts) nd in ll tretments in November 1995 thn in the A. sper trnsplnts (November 1995 tretment mens for egg number per polyp rnged from to for nturlly growing A. sper compred with for the trnsplnted colonies).

30 208 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 9 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor sper trnsplnts in the experimentl microtolls t One Tree Reef in October 1994 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P, Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P , Totl C , P Egg totl Nitrogen Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P, Testes totl Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P, Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. In November 1994, the number of eggs per polyp ws significntly reduced in both the nitrogen tretments compred to the non-nitrogen tretments nd in the phosphorus tretments compred with the non-phosphorus tretments, with the lest number of eggs per polyp in the nitrogen plus phosphorus microtolls (2.4 compred with 10.9 for the controls) (Tbles 11 nd 12; Fig. 16). In November 1995, there were significntly more eggs per polyp in the phosphorus microtolls thn in the other tretments, nd

31 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 10 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor sper trnsplnts in the experimentl microtolls t One Tree Reef in November 1994 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Microtoll within N3P Totl C , P Egg totl Nitrogen , Phosphorus , Nit. by phos , Microtoll within N3P , Totl C , P Testes totl Nitrogen Phosphorus Nit. by phos , Microtoll within N3P , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus with microtoll number nested within the tretment interction. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. significntly fewer eggs in the nitrogen tretments (nitrogen nd nitrogen plus phosphorus) thn in the non-nitrogen tretments. The men size of eggs in the polyps of the A. sper colonies occurring nturlly in the microtolls ws similr to tht in the A. sper trnsplnts. In November 1994, the eggs were smller in the control microtolls thn those of the other tretments (Tble 11,

32 210 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 11 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor sper growing nturlly in the experimentl microtolls t One Tree Reef in November 1994 df SS MS F P Egg number Nitrogen , Phosphorus Nit. by phos Totl C , P Egg size Nitrogen Phosphorus , Nit. by phos Totl C , P Egg totl Nitrogen , Phosphorus Nit. by phos Totl C , P Testes totl Nitrogen , Phosphorus Nit. by phos Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. Fig. 17). In contrst, in November 1995 the eggs were smller in ll nutrient tretments compred with the controls (Tble 12, Fig. 17). The men egg totl ws greter in the Acropor sper occurring nturlly in the microtolls thn in A. sper trnsplnts. In November 1994 the egg totl ws significntly smller in the nitrogen tretments thn the non-nitrogen tretments. In November 1995 the egg totl in the nitrogen only microtolls ws smller thn ll other tretments (Tbles 11 nd 12; Fig. 18). The testes totl ws greter in the A. sper occurring nturlly in the control microtolls thn the A. sper trnsplnts in the

33 S. Wrd, P. Hrrison / J. Exp. Mr. Biol. Ecol. 246 (2000) Tble 12 Comprison of the number of eggs, the size of eggs, the egg totl (egg number3egg size) nd the testes totl of the Acropor sper growing nturlly in the experimentl microtolls t One Tree Reef in November 1995 df SS MS F P Egg number Nitrogen , Phosphorus , Nit. by phos , Totl C , P Egg size Nitrogen Phosphorus Nit. by phos Totl C , P Egg totl Nitrogen , Phosphorus , Nit by phos , Totl C , P Testes totl Nitrogen , Phosphorus , Nit. by phos , Totl C , P Two wy nested orthogonl nlyses of vrince were used. Tretments were presence or bsence of nitrogen nd presence or bsence of phosphorus. Dt were log(x11) trnsformed due to heterogeneity of vrinces. C denotes the Cochrn s test vlue. control corls in November 1994 by fctor of more thn five. In November 1995, the testes totl ws greter in the nturlly occurring A. sper in ll tretments compred with the trnsplnts. In November 1994, the testes totl ws significntly reduced in the nitrogen compred with the non-nitrogen tretments nd in the phosphorus tretments compred with the non-phosphorus tretments. The smllest testes totl occurred in the nitrogen plus phosphorus microtolls nd the men testes totl for this tretment ws less thn one fifth tht of the control tretment (Tbles 11 nd 12, Fig. 19). Results re summrised in Tble 13.