Behavioral Adaptations ofaplysiopsis enteromorphae to differing light and heat conditions

Transcription

1 Behaviral Adaptatins faplysipsis entermrphae t differing light and heat cnditins Jenna Kullusn Explratry 3, Adaptatins fmarine Animals, Dr. Charlie Hunter Oregn Institute fmarine Bilgy, University foregn, Charlestn, Oregn 97420

2 Intrductin Aplysipsis entermrphae ccurs n Pacific Nrthwest shres foregn and Washingtn. This pistbranch has a "lcal distributin ccurring (1) in high intertidal, pen cast pls n filamentus green algae and (2) in bays and estuaries n green algal mats" (Trwbridge, 1993). This species nly ccurs in the summer mnths. Similar species are fund arund the wrld in the same types fhabitats. Cynthia Trwbridge has nted, in a cnversatin, that these species all have a similar black pigment that culd prtect the individuals frm sun expsure. Much is knwn abut the bilgy, feeding habits and reprductin fthis sea slug, hwever infrmatin n varius behaviral adaptatins are missing. Lcally, A. entermrphae live in the gently slping mudflats fmetcalf marsh with in tide pls and tidal channels that are als hme t the green alga Cheatmrpha. I was curius ifindividuals are ever stranded utside f these water habitats. Ifthey are stranded, d they find their way back t the water r d they burrw within the sediment, much like many ftheir fellw mudflat neighbrs? Anther sacglssan fund at Metcalf Marsh, Alderia mdesta, mves arund n Vaucheria mats in the daytime, hwever slugs burrw int the algal mats with increased emergence time, particularly n warm r bright days (Trwbridge, 2002). In additin, des light and heat affect the behavir fa. entermrphae? I believe they will burrw int the sediment if sunlight r extreme heat is present and water cver is absent. When the individuals are cvered by water I expect them t be unharmed and t maintain nrmal behavir under varying light/heat cnditins. Alternatively, the Aplysipsis will have n change in behavir between different light/heat expsures with r withut water. I will lk specifically fr the presence fburrwing behavir and aversin t heat and light expsure, including expsure t high sun levels. Methds & Materials T examine the behavir faplysipsis entermrphae in different light and heat cnditins I cllected 12 individuals frm MetcalfMarsh in Charlestn, Oregn. Here I fund the species within a large tidal channel in the mid t high zne fthe mudflat. I

3 cllected the sediment they were living n, but nly the tp layer t ensure I had an adequate and accurate layer fr the ptential burrwing. I als cllected Cheatmrpha fr the individuals t feed n t maintain similar field lifestyle. I set up 4 equal, shallw cntainers with sediment abut 2 cm deep. I placed three individuals in each cntainer fr my fur study grups. I allwed the slugs t settle in the tank envirnment fr tw days befre beginning my trials. My fur trials were as fllws: (1) N additinal light expsure, (2) One light expsure, (3) Tw light expsure and (4) Full sun expsure. The lights I used were standard desk lamps cntaining 69-watt bulbs. I used the same light fr the 2 nd trial t ensure n irregularities in light and heat increase/decrease. In the furth trial, I tk advantage fan unusual sunny day in Charlestn t test fr differing behavirs due t increased heat, light and UV expsure. I ran the 4 replicates fr trial 1, 2 and 3 fr ten minutes each while I ran trial 4 fr 15 minutes each t study the behavir mre clsely. The fur different trials were repeated twice with tw cntrls (cntainers expsed with 1.5cm fwater and tw experimental (cntainers withut water and cmpletely expsed sediment. After perfrming the first trial with n additinal light expsure I used the behavirs nted and temperatures as cntrls fr the fllwing trials. Here the "nrmal" behavir nted cnsisted ffraging and mvement arund the cntainer, while nted behavir fr the cntainers withut water is a lack fmvement. Fr the ther trials I lked fr these specific behavirs as the cntrl behavir while nting behavirs that differed. I quantified the number findividuals that displayed them. I als lked at the temperature increases fr the different trials and the differences between them. Results Behavirs seen in Trial 2 were the cntrl behavirs bserved in Trial 1. The temperature increases (figure 1) fthe water-cvered cntainers, used as the cntrl prtin fthe trial, shwed a change. The temperature increases fr the cntainers withut water increased at a mre extreme rate. The results fr Trial 3 began t shw burrwing behavir (figure 4) in tw individuals as well as tw individuals finding shade and water refuge when the cntainer was empty (figure 2). In the furth trial (figure 3),

4 mre burrwing behavir was bserved in experiments dne withut water cver. It was seen in 3 individuals while n mvement (cntrl behavir) was seen in ne individual. Cntainers with water cverage shwed individuals with cntrl/nrmal behavir. The majrity fthe slugs began shwing differing behavir within 5 minutes f the start f the expsure. Discussin Thrugh the trials I fund Aplysipsis entermrphae t display adaptive behavirs fr their envirnment. I bserved A. entermrphae t find refuge in the shade (while under water) and in small pls fwater, while slugs left ut fwater and expsed t intense light and heat displayed burrwing behavir. The individuals that displayed burrwing behavir were unsuccessful in cmpletely cvering themselves. Hwever this culd be due t a lack f time in my trials. Many sacglssans are able t perfrm kleptplasty, the ability t sequester undigested algae s as t create a surce fcarbn fr the slug, (Trwbridge, 2002). Hwever, A. entermrphae are an exceptin t this rule and d nt sequester chlrplasts. This leads me t think that A. entermrphae has n benefit fstaying in the sunlight, and instead wuld benefit frm desiccatin stress preventin by burrwing r heading fr shelter in an algal canpy. Trwbridge states that, "Atlantic species with functinal chlrplasts riented tward light whereas apsymbitic species avided light. Ifthis pattern were general, then mst nrtheastern Pacific species shuld avid light r perhaps be ncturnal because fthe general lack ffunctinal kleptplasty" (2002). There were surces ferrr in my explratry that culd have cntributed t sme fthe incnclusive behavirs. My inability t maintain an uncvered cntainer withut small pls fwater culd be a surce ferrr in slug behavir, especially ifthey ended up starting in ne fthese pls. Hwever I d feel that bumpy tpgraphy allwing fr small pls is indicative t their natural habitat, and therefre mre realistic. It wuld have als been a gd idea t run the trials fr the same amunt ftime, either 10 minutes r 15 minutes s that my temperature increases were mre accurate with ne anther. Due t the nature fthe explratry, defming individuals behavir is difficult and smetimes nt clear. Perfrming mre trials wuld have allwed me t see mre

5 examples and variatins n the same behavir. That way I culd have identified them mre accurately. Further explratin fthis subject culd include perfrming the same trials, but adding in algae t see ifthey mve t the prtectin. I culd examine whether r nt they have a habitat preference r the ability t mve t the deeper water r under algal shelter. This is especially after nticing their tendency t settle next t the thermmeter and shady edge fcntainer. References Trwbridge, Cynthia. "Nrtheastern Pacific Sacglssan Opisthbranchs: Natural Histry Review, bibligraphy, and Prspectus." The Veliger. 45 (2002): Trwbridge, Cynthia [persnal cnversatin]. Trwbridge, Cynthia. "Ppulatin Structure ftw Cmmn species 0 f Ascglssan (=Sacglssan) Opisthbranchs n the Central Cast foregn, USA." The Veliger. 36 (1993): Figure 1. Display ftemperature changes in the series ftrials with n light added (1), ne light expsure (2), tw light expsure (3) and expsure t full sun (4). U 30 ~ 25 G1..., ; 20 I! 15 G1 E10 G1 t , , -+- with water -- withut water Light added 4

6 Figure 2. Graph fvarius behavirs by individual Aplysipsis entermrphae nted during Trial 3 (tw light expsure). 7., , 6.!e as... 4 ~-~3... e 2 =It: 1 water n water Nrmal behavir N mvement Shade/water refuge Behavirs nted Burrwing behavir Figure 3. Graph fvarius behavirs by individual Aplysipsis entermrphae nted during Trial 4 (expsure t full sun). 3.5, , 3.!e II) 2.5 g ~-~ e 1 =It: 0.5 Nrmal behavir water n water N mvement Shade/water refuge Behavirs nted Burrwing behavir

7 Figure 4. Aplysipsis entermrphae burrwing behavir is seen here with bth individuals. Nte the sediment cvering which is achieved by mucus secretins and twisting f the slug t cver itself.