13 International Journal of Research in Marine Sciences 2013; 2(1): 13-25

Original Article

Marine Wood Borer Communities of Visakhapatnam harbour, India:

Spatiotemporal Patterns and Environmental Drivers

S.K. Pati1*

, M.V. Rao2, and M. Balaji

3

1Zoological Survey of India, Western Regional Centre, Vidya Nagar, Sector No. 29, P.C.N.T Post, Rawet Road, Akurdi,

Pune- 411 044, India 2, 3

Wood Biodegradation Centre (Marine), Institute of Wood Science and Technology, Beach Road, Via Yoga Village,

Andhra University Post, Visakhapatnam 530 003, India *Correspondence author Email: sameer_pati@yahoo.co.in

Received 26 April 2013; accepted 02 May 2013

Abstract

Information on marine wood borers and their ecology in harbour area is highly essential to evolve timber damage control

strategies. Thus, community structures of wood borers were studied in the polluted Visakhapatnam harbour at three

stations (Slipway Complex, Ore Berth and Marine Foreman Jetty) from February 2007 to January 2009. Monthly and

cumulative wooden panels were used for the study. Data on various environmental parameters and biofouling were also

recorded. During the study, a total of 29 species of wood borers were encountered at Visakhapatnam harbour, of which 13

taxa were recorded for the first time. Diversity and species richness of borers in monthly panels increased from Slipway

Complex to Ore Berth, but sharply declined from Ore Berth to Marine Foreman Jetty. In general, diversity and species

richness of borers in cumulative panels at all the stations increased in direct relation to the exposure period of the panels.

A marginal temporal variation was observed in borer species count at Slipway Complex while a sharp difference in borer

attack was noticed in cumulative panels during 2nd

year at Ore Berth. The environmental parameters affecting spatial and

temporal variations in wood boring communities were discussed.

2013 Universal Research Publications. All rights reserved

Key words: Wood Borer, Community Structure, Environmental Parameters, Visakhapatnam harbour, India.

1. Introduction

Wood was the most important material, next to stone, used

by primeval man to exploit food and explore new frontiers.

Despite the passage of several centuries and advent of

several modern construction materials such as cement,

metals, alloys, rubber, plastic, perspex, FRP, etc. timber

retained its status as a pristine structural material due to its

many virtues such as light weight, high strength, non-

corrosiveness, non-magnetic nature and fidelity to be

shaped, bent or joined [1, 2]. Wood is in wide use for

harbour structures such as piles, piers, wharves,

floating/static fenders, dock blocks, groynes, marinas and

fishing craft such as dinghies, canoes, catamarans,

pontoons, boats and several cruising/transport vessels.

However, wood under marine condition is severely

attacked by borers, which penetrate into the very core of

the material and cause huge material and monetary losses.

Inventory of marine wood boring animals in a coastal area

helps in documentation of the spread and activity of the

deteriogens, besides furthering knowledge on the ecology

of borers which is a prerequisite to evolve timber damage

control strategies [3, 4]. Hence, work on different aspects

related to the subject has been going on in various maritime

nations around the world. Though several ecological

researches were conducted on these animals [58], studies

related to marine wood borer communities are limited in

tropical countries like India. Ganapati and Nagabhushanam

[9] and Nagabhushanam [1012] reported many crustacean

and molluscan borers in Visakhapatnam harbour.

However, community structure of marine wood borers was

not studied by these researchers. Moreover, several

physical, chemical and biological changes have been taking

place in Visakhapatnam harbour during the past couple of

decades due to developmental and anthropogenic pressures.

Hence, community structures of marine wood borers at

Visakhapatnam harbour were analyzed to address the

problem.

2. Material and methods Studies on marine wood borers were conducted for a period

of two years from February 2007 to January 2009 in

Visakhapatnam harbour (1740N and 8316E) (Fig. 1) at

three stations, namely, Slipway Complex (SWC), Ore Berth

(OB) and Marine Foreman Jetty (MFJ). Slipway Complex

situated in the less polluted outer harbour while Ore Berth

and Marine Foreman Jetty located near moderately polluted

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14 International Journal of Research in Marine Sciences 2013; 2(1): 13-25

[13] entrance channel and in severely polluted inner

harbour, respectively.

Vertical ladders each containing six wooden test panels

(each panel having a size of 150 8020mm) were

immersed at each of the three stations in such a way that

the uppermost panel of the ladder lied in the intertidal zone

and the rest panels were below the lowest low water mark

with a gap of 100 mm in between each of them. For

monthly observations, one ladder [containing panels of a

broad-leaved soft wood species, Bombax ceiba (Semul)

due to its quick susceptibility for early settlement and easy

growth of boring organisms] each was put to marine

exposure for one month at each of the three stations during

each of the 24 months whereas for cumulative

observations, twelve ladders [containing panels of a

relatively durable timber of the soft wood species

(Gymnosperm), Pinus roxburghii (Pine) to obtain data on

cumulative pattern] were immersed at one and the same

time at the beginning of each year and retrieved single

ladder-wise from each station at the end of each month

consecutively till salvation. After retrieval of ladders,

fouling groups on each panel were identified and counted;

fouling cover was estimated and fouling accumulation were

removed for calculating wet biomass. The panels, after

extraction of relevant data on fouling, were utilized to

collect information on marine wood borers. Limnoriids in

the tunnels were first disturbed by a gentle jet of freshwater

and the animals that emerged out on to the timber surface

collected with a fine brush and preserved in 70% ethyl

alcohol modified with glycerin. Pholadids and teredinids

were extracted from the tunnels of each panel after

dissecting the panels carefully and same were preserved

similarly like that of limnoriids. Subsequently, the animals

were identified following the keys of Krishna Pillai [14],

Turner [15] and Turner and Santhakumaran [16]. The

average count of each species of borers and foulers

obtained from the six replicate panels was considered as

their abundance (number of individuals.m-2

) for that

month/period. However, in critical cases where panels

were heavily destroyed (approximately 4% of total panels

studied) and most animals (except limnoriids) perished,

pholadids were enumerated based on the characteristic

nature of their entry points and teredinids based on the

number of pallet-sets recovered.

Fig. 1: Map of Visakhapatnam harbour

Community structure of the wood borers in monthly and

cumulative panels was separately analyzed using standard

univariate statistical indices, viz., Shannons diversity index

(H), total abundance (N) and species richness (S) as per

Magurran [17] with the aid of software PAST version

1.96 [18]. Multivariate method of ordination (non-metric

multi-dimensional scaling) was employed on the abundance

of all wood boring species obtained from monthly panels at

the three stations during the two years using PRIMER 6

software version 6.1 [19].

Surface water temperature, pH, salinity and dissolved

oxygen at each station were estimated using standard

methods [20, 21].

3. Results 3.1 Environmental conditions Mean temperature between the two years at each station

and among the three stations during each year were more or

less equal (Table 1). The magnitude of temperature

variation at each station was relatively high during 1st year

than 2nd

year. Mean temperature was highest at Marine

Foreman Jetty during 1st year and at Ore Berth during 2

nd

year. Mean salinity was higher during 1st year than 2

nd year

at all the stations. Its magnitude of variation was higher

during 2nd

year than 1st year at each station. Salinity

showed a slightly decreasing gradient from Slipway

Complex through Ore Berth to Marine Foreman Jetty

during both the years. Mean pH was higher during 1st year

than 2nd

year except at Ore Berth. pH variation was higher

during 1st year than 2

nd year at Slipway Complex and

Marine Foreman Jetty, but equal at Ore Berth. This

parameter depicted a gradually decreasing gradient from

Slipway Complex through Ore Berth to Marine Foreman

Jetty except Ore Berth during 2nd

year. Mean di