Indian Journal of Marine Sciences Vol. 39(1), March 2010, pp. 57-67

Seasonal influence on settlement, distribution and diversity of fouling organisms at harbour

B S Swami* & M Udhayakumar Marine Biotechnology Department, Naval Materials Research Laboratory, DRDO, Anandnagar P.O. Ambernath(E) - 421 506, Maharastra India *[E-mail: [email protected]]

Received 9 September 2008; revised 15 December 2008

Biofouling at two sites was examined with regard to species abundance (density) and its composition. Sixty species were recorded during the investigation period (2000 – 2001). These species mainly belong to phylum annelida (11 species), bryozoa (22 species), cirripedes (4 species), mollusca (5 species.), coelenterata (6 species), tunicata (10 species) and porifera (2 species). Thirty five species have been recorded from tidal basin. Which is influenced by organic pollutants released through sewage water. Among sixty recorded species, 16 were new records from the region. There is significant variation in density from month to month at Near-shore waters and at Tidal basin. Species settled in pre-monsoon were significantly higher than species settled in monsoon and post monsoon. Settlement pattern varies with seasons at Near-shore waters and at Tidal basin.

[Keywords: Biofouling, seasonal variation, density, species composition, pollution, biodiversity]

Introduction Mumbai harbour, was aimed at a particular aspect at a Problems related to the settlement of marine particular part of time, was reported periodically. organisms are not confined only to ship hulls and ship Present study elucidates the biodiversity of fouling machinery, but also affects the other shore based species and their settlement pattern under a changing installations such as coastal power stations, chemical scenario in harbour activities. Emphasis was laid to and desalination plants which use sea water as cooling generate information on biofouling with regard to medium. Quality and quantity of fouling assemblage community abundance and species composition at at a given site or environment depend on its biotic and two sites viz. Near-shore waters and Tidal basin of hydrographical conditions. Mumbai harbour. Fouling adds to the weight and volume of the immersed structures, generates debris, induces Materials and Methods corrosion, impairs functioning of moving parts, 1. Exposure sites : In order to assess the settlement, increases drag and creates several other problems 1. As distribution and species composition of biofoulers, a result of this the operational and maintenance costs perspex test coupons were exposed at two study sites get significantly increased 2. The economic loss due to (Fig. 1) of Mumbai harbour (lat. 18° 55' N; long. damage caused by fouling organisms in India is 72° 50' E) during June, 2000- September, 2001. stupendous. About 360 million rupees are spent i) Near-shore waters (St.1) : Near-shore waters is annually to maintain boats and ships to keep them free an open sea having a good tidal flow. It is located at from fouling 3. Oil and Natural Gas Commission the mouth of -Mumbai Bay. Water is relatively (ONGC) spends about Rs.120 million annually to clean and is subject to diurnal tidal flow. Maximum maintain their platforms keeping free from fouling. It depth at this site is 15 metres. has been established that shut down of a 235 MW(e) ii) Tidal basin (St.2): It is semi-enclosed water power station due to biofouling costs about Rs. 40 close to the shore and receives untreated sewage lakhs a day 4. Dead organisms cause local corrosion on through storm water-culvert. During monsoon, a metal surfaces immersed in seawater leading to considerable amount of rain water enters the tidal crevices and pits 5. Due to such adverse consequences basin, causing wide and frequent fluctuations in of fouling, much work has been done on the subject. salinity. The site supports a good growth of sulfate Good amount of information has been generated in reducing bacteria, which contribute to severe Indian tropical waters 6-23 . The works on biofouling at corrosion 24 . The depth of water at this site is 8 metres. 58 INDIAN J. MAR. SCI. VOL. 39 NO. 1, MARCH 2010

kept for air drying for 8-10 days. Data collected were statistically analysed 26 .

Results

Hydrography : Near shore waters and Tidal basin differ from each other in respect of their water quality. Water quality status at near shore waters remained stable. Temperature, salinity, dissolved oxygen (DO), total suspended solids (TSS) and pH here ranged from 26.2-31.9 °C, 22.12-36.21‰, 3.56-6.57 mg.l -1, 35.6-249.2 mg.l -1 and 7.71–8.15 respectively. In comparison to Near shore waters, the water quality at Tidal basin (St.2) is found to be polluted. Dissolved oxygen content was considerably low and ranged between 0.55 and 7.49 mg.l -1. Salinity fluctuation was wide during monsoon. Temperature, salinity and TSS ranged from 26.8-32.0°C, 16.26-35.81‰ and 6.8-37.6 mg.l -1 respectively. The pH ranged from 7.28-7.95. The low value of 7.28 was recorded in April, 2001. Organic sewage released through storm water-culvert resulted in depletion of dissolved -1 O2 content to an extent of 0.55 mg.l during June, 2001 (Table 1). Biological oxygen demand (BOD) reported in an earlier study was ranged from 36–85 mgl -1. This was reported as polluted 2,24,27- 28 .

Characterization of biofouling

Near-shore waters (St. 1) Fig. 1—Map showing the study stations (1) Near-shor e waters, (2) Tidal basin Density Sedentary organisms settled on test panels comprised 2. Exposure of the coupons : In field exposure heterogeneous groups. Species mainly belonged to studies for collecting data on various biological phyllum Ectoprocta, Annelida, Arthropoda, Mollusca, aspects, pre-weighed test panels of perspex, (size 15 × and Ascidia (Urochordata). In the present study, 60 16 × 0.4 cm) were bolted on mild steel frames and animal taxa (Table 2) were recorded. were immersed 1 metre below the low tide mark at Figure 2 shows the density (number of individuals each station. A new set of 10-12 test panels was of all species) of biofoul recorded at St. 1 and immersed at every calendar month and an equal St. 2 during different months. During the early period number was withdrawn for examining the biota under of immersion (June-July, 2000), the density was not live condition-non-destructively. uniform. Gradual increase in density was observed 3. Examination of the coupons : Test panels from July to September, 2000. The number of (coupons) were examined under stereo-microscope individuals increased to an extent of 9716/m 2 in (Zeiss). Census of each individual was made using September. Polychaeta and bryozoan species square grid method 25 . A thin perspex sheet was contributed to an extent of 90% of the density. engraved with squares of 1 cm. and superimposed on Density ranged between 1877 and 12,069 the test panel. Biota assessed was characterized with individuals/m 2. Highest growth was recorded during regard to its density and species composition. Coupon September, 2001, whereas low density was recorded area of 15 × 12 cm (180 sq. cm.) was actually in July, 2001. screened. After examination of the biota, the panels The difference between the number of individuals were preserved in 5% formalin for 6 hours and were settled in June and July was insignificant, while SWAMI & UDHAYAKUMAR : SEASONAL INFLUENCE ON SETTLEMENT, DISTRIBUTION AND DIVERSITY 59

[ Table 1 —Hydrographical conditions of Mumbai harbour Period Near shore waters (St.1) Tidal basin (St.2) Temp. pH Saln DO TSS Temp. pH Salin. DO TSS (oC) (ppt.) (mg/l) (mg/l) (oC) (ppt.) (mg/l) (mg/l) Monsoon

June’00 31.5 7.77 30.81 5.84 69.20 31.60 7.70 35.57 1.46 25.6 July 29.2 7.86 27.87 5.89 245.60 29.20 7.71 22.21 4.47 14.4 Aug. 29.5 7.85 27.89 5.66 179.60 29.50 7.61 23.08 4.56 21.2 Sept. 29.5 8.15 30.45 6.30 118.40 29.60 7.95 31.40 4.00 37.6

Post-monsoon

Oct. 30.3 7.91 34.92 4.47 73.2 31.2 7.86 33.65 2.74 37.2 Nov. 28.7 7.95 34.92 4.47 37.2 29.6 7.85 34.29 3.83 13.6 Dec. 27.0 7.71 35.87 5.21 35.6 27.5 7.49 34.92 7.49 9.6 Jan’01 26.2 7.84 35.50 6.20 40.0 26.8 7.71 34.92 3.56 9.6

Pre-monsoon

Feb. 27.2 7.92 35.57 5.2 46.6 27.1 7.77 35.81 4.29 6.8 Mar. 28.1 7.99 34.92 6.29 56.4 28.0 7.75 35.25 5.39 24.8 Apr. 30.4 7.94 36.21 5.29 202.8 30.5 7.28 35.81 1.83 18.8 May 31.1 7.91 36.21 4.19 144.0 30.8 7.68 35.25 2.09 16.0

Monsoon

June 31.9 7.88 35.81 3.56 170.0 32. 0 7.61 35.81 0.55 103.6 July 29.3 7.93 23.72 4.47 986.0 29.0 7.66 16.26 5.58 30.8 Aug. 29.1 7.95 22.12 6.57 35.7 28.9 7.78 21.16 3.74 21.2 Sept. 29.3 7.92 31.73 5.82 249.2 29.4 7.83 23.72 4.12 28.6 Temp.= Temperature, Saln. = Salinity, DO = Dissolved oxygen, TSS = Total suspended solids during subsequent months i.e. July to September it effect of monsoon. However, the monsoon density was highly significant (p<0.00005). This has occurred was significantly higher than that of post-monsoon due to heavy and varied settlement of polychaete season (p< 0.005). species such as H. elegans, H. operculatus and D. cingulata . Table 3 shows the estimated significant Species composition Species diversity at Near-shore waters was very levels i.e. ‘p’ and ‘t’ values of biofoulers settled in high. Study revealed that as many as 60 species were various months. Out of fifteen months observation, recorded from St. 1. Species composition was the difference in density was found to be highly ectoprocta (20 species), polychaetes (6 species), significant (p<0.00005) in 9 months, while at 2 cirripedes (4 species), ascidians (10 species), molluscs occasions the difference remained significant. (3 species), hydroids (5 species), porifera 2 and others Seasonal difference in population density was high 10 (Table 2). at Near-shore waters compared to Tidal basin. Figure 3 shows the month wise total species Average density in pre-monsoon, monsoon and recorded at St. 1 and St. 2. Although the number of post-monsoon were 6708 ± 1674, 5655 ± 1446 and species settled at the beginning was not high, 4785 ± 911 respectively. Settlement of fouling substantial increase had occurred during August individuals during pre-monsoon was significantly (17 ± 2). This had been continued till the end of higher than the settlements recorded during monsoon September 2000 when 19 species were encountered. and post-monsoon periods (Table 4). During Settling pattern showed marked variations in each monsoon, as expected, the density was significantly month. During October-December the species less than those of pre-monsoon period, indicating the settlement however was uniform. Species number 60 INDIAN J. MAR. SCI. VOL. 39 NO. 1, MARCH 2010

[ Table 2—The check list of biofouling species recorded from two study stations at Mumbai harbour Name of the species St. 1 St. 2 Name of the species St. 1 St. 2 Coelenterata Ba ugula stolonifer A P Companularia sp. P P Savignyella sebogi P A Obelia sp. P P Scrupocellaria scruposa P A Clytia sp. P A Zoobotryon verticellatum P A Sertularia sp. P A Victorella pavida P P Plumularia sp. P P Amethia convoluta P A Tubularia sp A P Nellia tenella P A Annelida Electra bellula* P A Hydroides elegans Nolella popuenensis A P P P Hydroides operculatus* P A Cerripedes Apomatus sp. P A Balanus variegatus P P Pomatoleus sp. A P Balanus reticulatus P P Ficopomatus uschakovi* A P Chirona amaryllis euamaryllis P P Chaetopterus variopedatus P P Megabalanus tintinnabulum P A Dasycone cingulata P P Mollusca Pseudobranchiomma orientalis* P P Crassostrea graphoides P A Branchiomma cingulatum* A P Crassostrea sp. P A Jasmineria sp* A P Saccostrea cucullata P A Demonax leucaspis* A P Mytilopsis sallei A P Bryozoa (encrusting) Oyster sp. A P Electra bengalensis P P Tunicata Membranipora annae P A Symplegma reptans P P Membranipora tenuis P A Symplegma brakenbielmi P P Membranipora sp. P A Symplegma viride* P P Membranipora saverti P A Botrylloids magnicoecum* P P Acanthodesia sp. P P Botrylloids chevalense* P A Alderina arabianensis* P P Diplosoma macdonaldi* P P Hippoporina americana P P Ascidia sydneiensis* P P Hippopodina feegeensis P A Ascidia indica* P P Electra crustulenta* P A Styela bicolor P P Clothrudium sp*. P A Ecteinascidia sp. P P Bryozoa (erect forms) Porifera Bugula bengalensis Leucosolenia sp. P P P A Bugula neritina P A Sycone sp. P A Others 10 - P = present A = absent * recorded for the first time ranged between 11 and 28. Lowest number of species of species settled during September 2001 was was recorded during the monsoon month of July and significantly higher than that in August (p < 0.00005). highest number (28/panel) in the pre-monsoon month Analysis of data showed that as many as 11 species of of February, 2001. bryozoans were encountered during this month and In July and August 2001, species number reduced contributed in enhancing the ‘p’ value to the order of to 11. This drastic decrease in species was mainly due p<0.00005. to monsoon effect. In September 2001, the number It was observed that the maximum species increased by two fold (22/panel), when most of the settlement took place during pre-monsoon period hydrographical parameters remained stable. Number while minimum occurred in monsoon season. The SWAMI & UDHAYAKUMAR : SEASONAL INFLUENCE ON SETTLEMENT, DISTRIBUTION AND DIVERSITY 61

Fig. 2—Monthly variations in population density of biofoulers in Mumbai harbour

Table 3—Satistical analysis of the biofouling organisms settled at Near-shore waters (St. 1)

Period Density (no/m 2) Species composition(no/panel) Mon. – Mon. ‘n’ ‘t’ ‘p’ ‘n’ ‘t’ ‘p’ Monsson June – July’00 14 1.38 NS 14 1.86 NS July – Aug. 14 5.20 p<0.0002 14 4.25 p<0.001 Aug. – Sept. 15 3.20 p=0.005 15 1.5 NS Sept. –Oct. 16 9.77 p<0.00005 16 3.05 p<0.01 Post-monsoon Oct. – Nov. 18 0.69 NS 18 1.07 NS Nov. – Dec. 15 2.59 p<0.05 15 1.0 NS Dec. – Jan.’01 16 8.88 p<0.00005 16 6.86 p<0.00005 Jan.– Feb. 19 4.36 p<0.0005 19 5.08 p<0.0005 Pre-Monsoon Feb. - mar. 19 1.39 NS 19 2.18 p<0.05 Mar. – Apr. 20 5.38 p<0.00005 20 4.23 p<0.0005 Apr. - May 19 6.30 p<0.00005 19 3.29 p<0.005 May - June 18 6.35 p<0.00005 18 3.19 p<0.005 Monsoon June – July 17 1.64 NS 17 3.09 p<0.01 July – Aug. 18 2.33 p<0.05 18 0.84 NS Aug. – Sept. 20 13.07 p<0.00005 20 8.20 p<0.00005 Month = number of samples. ‘t’ = student’s ‘t’ test, p = level of significance, NS = not significant. average species recorded during pre-monsoon, Tidal basin (St. 2) monsoon and post-monsoon were 23 ± 5, 15 ± 4 and The site is situated about 500 m away from Near 18 ± 3 respectively. The numbers of species settled in shore waters and is continuously under the influence pre-monsoon season were significantly higher of sewage pollution menace. Karande and 24 than those of the monsoon and post monsoon Srivastava have identified as a polluted area seasons (Table 4). influenced by organic pollution. Being a polluted 62 INDIAN J. MAR. SCI. VOL. 39 NO. 1, MARCH 2010

Table 4—Seasonal variations and significant level of biofoulants settled at St. 1 and St. 2 Season Density (no/m 2) Species comp. (no/panel) Mean SD Mean SD Near-shore waters (St. 1) Pre – mon. 6708 ± 1674 23 ± 5 Monsoon 5655 ± 1446 15 ± 4 Post-mon. 4785 ± 911 18 ± 3 Tidal basin (St. 2) Pre-mon. 45393 ± 9106 16 ± 4 Monsoon 6099 ± 13556 12 ± 5 Post-mon. 6006 ± 14191 15 ± 3

Seasons Density Species composition ‘n’ ‘t’ ‘p’ ‘t’ ‘p’ Near-shore waters Pre-mon. X Mon. 75 2.91 p<0.005 7.69 p<0.00005 Mon. X Post-mon. 71 3.09 p<0.005 3.61 p<0.001 Post-mon. X Pre-mon. 72 6.06 p<0.00005 5.2 p<0.00005 Tidal basin Pre-mon. X Mon. 82 6.1 p<0.00005 3.96 p>0.00005 Mon. X Post-mon. 76 0.29 NS 3.15 p<0.005 Post-mon. X Pre-mon. 82 5.47 p<0.00005 1.30 NS SD = Standard deviation, NS = not significant, Pre mon = Pre-monsoon, Post-mon = Post monsoon

Fig. 3— Monthly variations in species composition of biofoulers in Mumbai harbour zone, the colonization of biofoulants is bound to be observed between different months. This statistical different from Near-shore waters. analysis showed that the level of significance (‘p’ value) between the months remained very high at Density 13 occasions (Table 5). Population density here varied between 3610 Despite the low salinity during the monsoon, there and 143691 individuals/m 2 with highest value was was a good growth of polychaetes in this location. recorded in September 2000 and lowest value in The colonies recorded during monsoon season were January, 2001(Fig. 2). Well pronounced variation was significantly higher than those recorded in pre- SWAMI & UDHAYAKUMAR : SEASONAL INFLUENCE ON SETTLEMENT, DISTRIBUTION AND DIVERSITY 63

[ Table 5—Statistical analysis of the fouling organisms settled at Tidal basin (St. 2) Period Density (no/m 2) Species composition (no/panel) Mon. – Mon. ‘ n’ ‘t’ ‘ p’ ‘ n’ ‘ t’ ‘ p’ Monsoon June – July’00 18 5.28 p< 0.00005 18 1.06 NS July – Aug. 18 3.14 p< 0. 005 18 2.13 p< 0.05 Aug.- Sept. 20 15.59 p<0.00005 20 6.38 p< 0.00005 Sept.- Oct. 18 17.83 P<0.00005 18 4.82 P< 0.0002 Post-monsoon Oct. – Nov. 18 19.95 P< 0.00005 18 3.19 p = 0.005 Nov. – Dec. 20 4.84 P< 0.0001 20 2.25 p< 0.05 Dec. –Jan. 20 9.09 P< 0.00005 20 4.38 P< 0.0005 Jan’01 - Feb. 22 3.25 P< 0.005 22 1.85 NS Pre-monsoon Feb. – Mar. 24 20.69 P< 0.00005 24 1.94 NS Mar.- Apr. 22 15.64 P< 0.00005 22 1.87 NS Apr.- May 20 4.92 P< 0.0001 20 5.08 P< 0.0001 May – June 20 1.74 NS 20 1.69 NS Monsoon June – July 20 4.03 P< 0.001 20 0.88 NS Jul. – Aug. 19 1.97 NS 19 0.87 NS Aug. – sept. 19 30.79 P< 0.00005 19 5.08 P< 0.0001 NS = Not significant monsoon (p< 0.00005). Almost same level of significant variations in month-to-month species significance was observed when individuals settled occurrence. The species settling in April were during post-monsoon were compared with the significantly higher than those settled in May. The settlement recorded of the pre-monsoon season settlement scenario (Fig. 3) shows that it gradually (Table 4). However, number of individuals settled reduced from February to August 2001, showing no during monsoon and post-monsoon were same. significant difference. The number of species settled during pre-monsoon Species composition and post-monsoon season was significantly more than Total 35 species were recorded from this polluted the species settled in monsoon. However, species site. The dominant groups here were 9 species of settled in pre-monsoon and post-monsoon were polychaetes, 8 species of bryozoans, (4 encrusting and almost same, there being no significant difference. 4 erect bryozoans), 9 species of ascidians, 3 species of Maximum settlement was recorded during pre- cirripedes, 2 species of molluscs, and 4 species monsoon, whereas minimum number (n=12) was in of hydroids. monsoon (Table 4). The lowest number of 7 species was encountered in July which rose to 20 in February 2001 (Fig. 3). Species distribution Initially, the species congregation in June and July Bryozoans : Near shore waters supported the were less, which increased from July through settlement of 11 encrusting bryozoan species, whereas Tidal basin supported only 4 species. The common September 2000. The number of species occurring species recorded at Near shore waters were during September was significantly more than the E. bengalensis, A. arabianensis, M. annae and species that occurred in August and October 2000 H. americana. The other species encountered here are (p< 0.00005 and p < 0.0002 respectively). It was M. tenuis, Membranipora spp, M. saverti , two species highest (19/panel) in monsoon. During post-monsoon of Hippoporina , E. crustulenta and Clothrudium spp. months of October-January, the species occurring in Similarly E. bengalensis and A. arabianensis were each month varied, the difference estimated was common at Tidal basin. In total four erect bryozoans significant (Table 5). From February to the end of the were recorded at Tidal basin, as against 9 species study period, barring two occasions, there was no from Near-shore waters. 64 INDIAN J. MAR. SCI. VOL. 39 NO. 1, MARCH 2010

Polychaetes : Six species have been recorded undertaken to collect information on changes in at Near shore waters. Of these, H. elegans, species richness and its occurrence in relation to the H. operculatus , and D. cingulata were common. Nine seasonal variations and pollution stress. species were recorded from tidal basin. Of these, H. elegans, F. uschakovi , and C. variopedatus were Density the most common and dominant. Three mucilaginous Present study revealed that the number of tube-worms namely B. cingulatum, Jasmineria sp. individuals settled on test panels immersed in near- and D. leucaspis encountered for the first time at shore waters (St.1) and Tidal basin (St.2) showed Tidal basin. significant month-to-month variations. In order to Ascidians : Near shore waters and Tidal basin assess the extent of variations the data were supported almost equal numbers of ascidian species. statistically analysed and level of significance Ten species were recorded at Near shore waters and 9 (‘ p’values) was estimated (Tables 3 & 5). Of the 24 at Tidal basin. At Tidal basin, A. sydneiensis and significant values recorded at two sites, on 83.3% S. reptans were common, whereas at Near-shore occasions, i.e. 20 times, the difference noted between waters S. reptans, B. magnicoecum and months was highly significant (p<0.00005). It is obvious that the density recorded at both sites varied S. brakenbielmi were common. B. chevalense did not 29 settle at Tidal basin. from month to month. Depalma stated that density Cirripedes : Four species viz. B. variegatus, (population abundance) is an ideal and reliable B. reticulatus, C. amaryllis euamaryllis. and parameter to study the biofouling in marine M. tintinnabulum were recorded at Near shore environment. Density would enable the biologist to understand the variations in biofouling in relation to waters. While two species viz. B. variegatus and 30 B. reticulatus were commonly found at Near-shore the time and material used. Boyd (1972) stated that waters. Three species viz. B. variegatus, B. reticulatus no two panels in the series were exactly similar in and C. amaryllis euamaryllis were recorded at Tidal respect of fouling settlement. We too have made same observations among the panels immersed at Mumbai basin . Of these, the first two species were seen 31 abundantly during September and November 2000. harbour. Mook also observed the variations in Molluscs : Generally settlement of molluscan species numbers among five replicate panels exposed species at Mumbai harbour was poor. At Tidal basin, in estuarine waters. Earlier, the study conducted at Mumbai harbour reported considerable variations only two species viz. O yster sp. and M. sallei were 22,32-34 settled. Interestingly, these two species did not occur among the monthly panels . The present at Near-shore waters. The species C. gryphoides, observations corroborate not only with our earlier Crassostrea spp. and S. cucullata settled at Near- work at Mumbai harbour, but also with the shore waters. observations made at other locations on east coast of India 15,17-18 . Hydroids : Five species viz. Companularia sp. 2 Obelia sp . Plumularia sp. Clytia sp . and Sertularia sp . Density varied from 1877 to 12,069/m at near-shore settled at Near-shore waters while four species, viz. waters. This wide variation was attributed to the seasonal conditions. The lowest value was recorded in Companularia sp . Obelia sp . Plumularia sp. and 2 Tubularia sp. settled at Tidal basin. Tubularia sp. July 2001, whereas highest value of 12,069/m was settled only at this polluted site. There was not much recorded in September, 2001. The low salinity difference in settlement hydroid species at Near-shore (23.72‰) during monsoon played an important role in waters and Tidal basin. reducing the density. Around 25% reduction in density was noted as compared to the density in the month of Discussion June when salinity was normal (35.81‰). Nair 8 stated Intensive field work was carried out to generate that salinity is an important parameter which regulates continuous data on biofouling and their settlement the settlement and distribution of macrofoulers. Swami pattern. It contributed substantially to the fouling and Karande 12 observed the influence of monsoon on information at Mumbai harbour, one of the busiest the settlement of fouling organisms at Mumbai harbour along the west coast of India. In view of harbour. In the present study, low density was due to increasing naval activities, the environmental status is the low salinity due to monsoon effect, in which not changing rapidly and in fact, this is affecting species only the density but also the species reduction has been diversity endemic to the harbour. The study was observed. The oligohaline species of erect and SWAMI & UDHAYAKUMAR : SEASONAL INFLUENCE ON SETTLEMENT, DISTRIBUTION AND DIVERSITY 65

encrusting bryozoans disappeared from the site due to monsoons at Mangalore port located along the west reduction in salinity. Sunilkumar 35 also reported low coast of India. Similar observations were made by density and low species richness during monsoon Khandeparkar et al .36 at the same port. This indicates season in Cochin waters. that seasonality brings changes not only in Seasonal variations in density were obvious. At population abundance but also in species composition. near-shore waters, density recorded during Species distribution pre-monsoon was significantly more than that The species were not evenly distributed at Near- recorded during monsoon and post-monsoon, whereas shore waters and polluted Tidal basin. As was evident at Tidal basin, a reverse trend was observed. Here, by the fact that 60 species were recorded from Near- density in monsoon was higher than that recorded in shore waters while 35 species from polluted Tidal pre-monsoon (p<0.00005). Such a reverse trend could basin. These sites differed from each other with be due to polycheate species, viz. H. elegans, regard to water quality. Dissolved oxygen content was F. uschakovi and C. variopedatus , which contributed considerably low at Tidal basin. The organic substantially to enhance the density. pollutants released through sewage water caused the depletion in oxygen contents to a critical level 27 . Species composition Salinity fluctuations were wide and frequent during The species composition recorded at Near shore 28 waters was significantly higher than that of Tidal monsoon at this site . Near-shore waters was basin. Sixty species were recorded from Near shore relatively clean with moderate fluctuations being open waters as against 35 species at Tidal basin. This could to sea. Thus it supported a variety of fouling species. be attributed to serwage pollution and wide variations Eleven variety of encrusting bryozoans were in salinity. At Near shore waters, the species diversity recorded from cleaner Near-shore waters whereas ranged between 11 and 28, the lowest number being from polluted Tidal basin, only 4 species were noted. recorded in the month of July and the highest number At Tidal basin almost 60% reduction in species was (28/panel) in the pre-monsoon month of February, evident. Pollution affected the bryozoan diversity at 2001. February is the period for onset of the pre- Tidal basin. Rao and Balaji 37 attributed the drastic monsoon season, when temperature starts increasing reduction in species settlement at Kakinada port to the and all parameters found to be within the normal sewage and oil pollution. Of the 37 species recorded, limits. The DO and salinity recorded during February only 11 could settle at the polluted site at Kakinada were 5.2 mg/l. and 35.57‰ respectively (Table 1). which involved maximum number of polychaete The normal and stable conditions have favoured the 35 species. Nair (1965) had stated that pollution and heavy settlement of biofoulers. Sunilkumar , observed high species number and density during pre- salinity to a larger extent can be the limiting factors of the environment, which affect considerably the monsoon at Cochin back waters as was noticed during 8 present study. fouling community . The other species viz. M. tenuis, At Tidal basin the number of species settled varied Membranipora spp, M. saverti , two species of genus between 7 and 20. The pattern of occurrence was Hippoporina , E. crustulenta and Clothrudium spp . similar to that of Near-shore waters. Here also the were also recorded as additional species at Near-shore maximum number of species settled in the month of waters. Four erect bryozoans were recorded at Tidal February (20/panel). Although polluted by sewage basin, whereas 9 species were recorded at the cleaner water, the hydrographical conditions recorded during Near-shore waters. The bryozoans not only provide February were found to be stable. This suggests that ideal surface for the settlement of other sedentary forms but may also induce metallic corrosion by the stable hydrographical conditions support the 38 growth of biota at both the sites. giving shelter to corrosion inducing bacteria . The observations on seasonal variations in species At Tidal basin polychaetes played a major role in composition revealed that maximum species settled increasing the density to the tune of 10-12 times during the pre-monsoon and minimum in the higher than those recorded at Near-shore waters. This monsoon season. However, at Tidal basin, species site is conducive for the growth of polychaetes, which settled during pre-monsoon and post-monsoon were receives a good amount of organic matter. As many as comparable, showing no significant difference. 9 species were recorded from the site. The species Venkat et al .21 observed the higher settlement of contributed substantially to the population ascidian species during pre-monsoon and post- abundance include H. elegans, Ficopomatus 66 INDIAN J. MAR. SCI. VOL. 39 NO. 1, MARCH 2010

uschakovi, Chaetopterus variopedatus, Branchiomma fouling bivalve Mytilopsis sallei (Recluz), Ph.D. thesis, cingulatum, and Pomatoleus sp. Of the nine species, Andhra University, India, 1988. 4 Nair K V K, Marine biofouling and allied problems in the six species were recorded for the first time from the 32 condensor cooling systems of MAPS, In: Marine Biofouling region. Swami reported that polychaetes were the in power plants, edited by K. V. K. Nair and V. P. most dominant group at Tidal basin. The present Venugopalan,(Bhabha Atomic Research Centre, Bombay), study revealed that at any time of the year, if the 1990, pp 92-103. rd panels are exposed, around 85% of the population 5 LaQue F L, Corrosion and fouling. In: Proceedings of 3 Inernational congress on marine corrosion and fouling NBS , density would be due to polychaetes. It is reported Gaithersburg, Maryland, USA, 1972, pp 2-13. that polychaetes have been used as biological 6 Daniel A, Seasonal variation and succession of fouling indicators of water quality for assessing the effects of communities in the Madras harbour, J Madras Univ., 24B industrialization and urbanization in various parts of (1954) 189 –212.

39 7 Iyengar S R, Gopalkrishnan,V. & Kelkar, V. V. Studies on the world . marine fouling organisms in Bombay harbour, Def. Sci. It is concluded from the present investigation, that Jour., 7(1957) 123 – 129. density and species composition recorded at two sites 8 Nair N U, Marine fouling in Indian waters, J. Sci. Ind. Res., showed well marked monthly as well as seasonal 24 (1965) 483-488. variations. The Tidal basin being subjected to sewage 9 Karande, A A, Studies on marine fouling and boring organisms in Bombay harbour, In: proceedings of 2nd pollution has low species diversity comprising only International congress on marine corrosion and fouling, some filter-feeding species such as polychaetes and 1968, pp 563 – 569. ascidians. In near-shore waters a large number of 10 Karande A A, Marine fouling and timber deterioration in sub sedentary species formed the marine fouling fauna. oceanic Island of Andaman, Indian J. Mar. Sci., 7(1978) As many as 60 species were recorded from the two 39 – 43. 11 Renganthan T K, Balakrishnan Nair, N. & Dharmaraj, K., sites of Mumbai harbour in which 16 species are Ecology of marine fouling organisms in Karapad creek, recorded for the first time. They include 4 bryozoans, Tuticorin Bay, Southeast coast of India, Indian J. Mar. Sci., 6 polychaetes and 6 species from tunicates. This study 11(1982) 32-137. is significant from the point of view of screening of 12 Swami B S & Karande A A, Recruitment and growth of marine organisms being rich with ascidians which are biofouling invertebrates during monsoon in Bombay waters, West coast of India, Indian J. Mar. Sci., 17(1988) 143-149. reported to have high potential for bioactive 40 13 Karande A. A & Swami B S, Importance of test coupons in compounds . Present study provided information on the assessment of marine biofouling community development species richness that would be of help to improve the in coastal waters of Bombay, India. Indian J. Mar. Sci., 17 strategies of fouling control. (1988) 317-321.

14 Anil A C & Wagh A B, Aspects of biofouling community in the Zuary estuary, Goa, India. In: Marine Biodeterioration: Acknowledgements Advance techniques applicable to Indian Ocean , edited by M Authors are thankful to Dr. J. Narayana Das, F Thompson, R Sarojini and R Nagabhushanam, (Oxford and Director, NMRL for his support and encouragement IBH Publishing Co. Pvt. New Delhi, 1988). pp. 529-537. during the work. We are grateful to Dr. H. A. T. 15 Nair K V K, Murugan P & Iswaran M S, Macrofoulant in Hove, Netherland and Dr. (Mrs) V. K. Meenakshi, Kalpakkam Coastal Waters of India, Indian J. Mar. Sci., 17 (1988) 341-343. Tuticorin, for identifying the polychaetes and 16 Sasikumar N, Rajagopal N S, Azariah J & Nair K.V K, ascidians respectively. Authors are also thankful to Seasonal and vertical distribution of macrofouling in Mr. Ramphular Chouthi, Technician ‘C’ for his Kalpakkam coastal waters, India. Indian J. Mar. Sci., 18 assistance in the field work. (1989) 270-275.

17 Maruthamuthu, S Eshawar, M Manickam, S T Ambalavanan, S Venkatachari & Balakrishnan K, Marine fouling on test References panels and in service structural steel in Tuticorin harbour, 1 Callow M E, The status and future of biocides in marine Indian J. Mar. Sci., 19 (1990) 68-70. biofouling prevention, In: proceedings on Recent advances in 18 Venugopalan V P & Wagh A B, Biofouling of an off-shore Marine Biofouling. Vol.3, edited by M. Fingerman, R. oil platform: faunal composition and biomass. Indian J. Mar. Nagabhushanam, and M. F. Thompson, (Oxford & IBH Sci., 19 (1990) 53-56. Publishing Co., New Delhi) 1999, pp.109 – 126. 19 Eashwar M, Maruthamuthu S & Manickam S T, An 2 Bohlanders G S, Biofilm effects on drags: Measurement on assessment of preference for position by tropical marine ships, In: Polymers in marine environment, The Institute of fouling organisms, Biofouling 3 (1991) 277 – 286. Marine Engineers, London, UK. 1991, Pp.135. 20 Swami B S & Karande A A, Encrusting bryozoans in Karwar 3 Balaji M, Investigations on biofouling at two ports in Andhra waters, central west coast of India. Indian J. Mar. Sci., 23 Pradesh, India and some aspects of toxicity of copper to (1994) 170-172. SWAMI & UDHAYAKUMAR : SEASONAL INFLUENCE ON SETTLEMENT, DISTRIBUTION AND DIVERSITY 67

21 Venkat K, Anil A C, Khandeparkar B C & Mokashe S S, 31 Mook D, Studies on fouling invertebrates in the Indian river, Ecology of ascidians in the macrofouling community of New I. Seasonality of settlement, Bull. Mar. Sci., 26(1976) Mangalore Port, Indian J. Mar. Sci., 24 (1995) 41-43. 610 – 615. 22 Swami B S & Gaonkar S N, Studies on the variability 32 Swami B S, Biofouling community, its structure and amongst macrofouling on test coupons exposed in Bombay development in Bombay harbour , M. Sc. Thesis, Bombay harbour, Indian J. Mar. Sci., 27 (1998) 333-339. University, India, 1987, pp 39. 23 Swami B S & Udhayakumar M, Biodiversity and seasonal 33 Udhayakumar M & Karande A A, Field notes on a fouling variations of macrofouling species settling on test panels serpulid, Hydroides elegans Haswell (Polychaeta: exposed in Near-shore waters of Mumbai, In: Proceedings of Serpulidae) present in confined waters of Bombay, Indian J. the National Seminar on New frontiers in Marine Bioscience Mar. Sci., 25 (1996) 133 –136. Research , edited by S. A. H. Abidi, M. Ravindran, R. 34 Swami B S & Chhapgar B F, Settlement pattern of ascidians Venkatesan and M. Vijayakumaran, (Allied Publishers Pvt. in harbour waters of Mumbai, west coast of India, Indian Ltd. Chennai,) 2004, pp.439 – 458. J. Mar. Sci., 31(3) (2002) 207-212. 24 Karande A A & Srivastava R B, Pollution of coastal sea 35 Sunilkumar R, Macrobenthos in the mangrove ecosystem of water and sulfate reducing bacteria, In : Proceedings of the Cochin back waters of Kerala (southwest coast of India), 6th Inernational Congress on Marine Corrosion and Fouling, Indian J. Mar. Sci., 24 (1995) 56-61. Athens, 1984 Barcelono, 347- 354. 36 Khandeparker D C, Anil A C & Venkat K, Larvae of fouling 25 Winston J E & Jackson J B C, Ecology of cryptic coral reef organisms and macrofouling at , west communities IV. Community development and life history of coast of India, Indian J. Mar. Sci., 24 (1995) 37 – 40. encrusting cheilostome bryozoa, J. Exp. Mar. Bio. Ecol., 76 37 Rao K S & Balaji M, Biological fouling at Port Kakinada, (1984) 1- 21. Godavari estuary, India. In: Marine Biodeterioration- 26 Trivedy R K & Goel P K, Chemical and biological methods Advanced Technology applicable to the Indian Ocean , for water pollution studies , (Environmental publications, edited by M. F. Thompson, R. Sarojini and R, Karad, India), 1984 pp. 186. Nagabhusanam (Oxford IBH Publishing Co., New Delhi), 27 Swami B S, Suryawanshi U G & Karande A. A, Water 1988 pp. 551 -574. quality status of Mumbai harbour- an update, Indian J. Mar. 38 Swami B S & Karande A A, Encrusting bryozoans in coastal Sci., 29 (2000) 111-115. waters of Bombay, Mahasagar – Bull. Nat. Inst. Oceanogr ., 28 Swami B S & Udhayakumar M, Observations on seasonal 20/4 (1994) 225-236 variations in hydrographical characters recorded at Mumbai 39 Pearson T H & Rosenberg R, Macrobenthic succession in harbour, J. Ecol. Envir. Conser., 13 (2) (2007) 383 – 394. relation to organic enrichment and pollution of the marine 29 DePalma J R, Fouling production in world ocean. In: environment, Oceanogr. Mar. Biol. Ann. Rev ., 16(1978) Proceeding of 6 th International Congress on Marine 229-311. Corrosion and Fouling , edited by Garsi, Barcelona, Athens, 40 Davis A R & Bremner J B, Potential antifouling natural 1984 237-244. products from ascidian : A Review. In Recent Advances in 30 Boyd M, Fouling community structure and development in Marine Biofouling, Vol.3, edited by M. Fingerman, R Bodega harbour , California. Ph.D. dessertation, University Nagabhushanam, and M F Thompson, (Oxford & IBH of California, Davis, 1972. Publishing Co., New Delhi), 1999 pp. 259.