Е V Pavlova - Annual dynamics of abundance biomass and survival of meroplankton in sevastopol bay black sea - страница 1
Е. V. Pavlova l, Dr., sci. (віоі), V. V. Murina 1, Dr., sd. (віоі), R. B. Kemp, 2 Prof., J. G. Wilson, 3 Prof.,
V. P. Parchevsky 1 Dr., Researcher
1Institute of Biology of the Southern Seas, Nakimov Ave.2, Sevastopol, Crimea, Ukraine 2 Institute of Biological Sciences, Edward Llwyd Building, University of Wales, Aberystwyth, SY23 3DA, U.K.
3 Zoology Department, Trinity College, Dublin 2, Ireland
ANNUAL DYNAMICS OF ABUNDANCE, BIOMASS AND SURVIVAL OF MEROPLANKTON IN SEVASTOPOL BAY, BLACK SEA
The first comprehensive data on species composition, abundance, biomass and survival (living/dead ratio) of meroplankton in Sevastopol Bay (Black Sea) are presented. Marked differences were observed between the years 1998 and 1999, and these could be attributed to the hydrology and the eutrophication status of the different parts of the Bay. Shannon index and selected community parameters (number of species, biomass, numbers of individuals) indicated that South Bay was the worst affected part of the Bay with the greatest eutrophication impact on the meroplankton. The early larval stages of the barnacle Balanus improvisus and of the polychaete Polydora sp. were the most sensitive to presumed environmental stresses. It is suggested that the mortality of certain ontogenetic stages of the meroplankton can be used as sensitive indicators of ecosystem health with good spatial discrimination. The canonical correlations between biological and environmental variables ranged from 86 - 87 %. Discriminant functions defined two well-defined subecosystems in the Bay. Long-term comparison with 1989/90 data for the Bay outlet showed that molluscan larval mortality had remained unchanged, while that of Polychaete and Cirripedia had more than doubled, suggesting that they could be sensitive to increased eutrophication in Sevastopol Bay.
Keywords: abundance, biomass, survival, meroplankton, environmental conditions, Sevastopol Bay, Black Sea (Ukraine)
Sevastopol Bay is industrialized and urbanized, typical of many other bays in the world and the greatly indented coastline favours the isolation of parts from the renewal effects of the sea or fresh water exchanges. In 1977, the entrance to Sevastopol Bay was further restricted by construction of a jetty. Concomitant changes in freshwater inflow and increases in sewage discharge have resulted in an escalating anthropogenic impact on Sevastopol Bay such that there has been a marked and consistent decline in quality status over the last 25 years [14, 19, 32, 40].
Sevastopol Bay was one of the first focuses of work on taxonomy and morphology of pelagic larvae in coastal regions and bays of the Black Sea [9, 17, 49]. Later work, after the construction of the jetty, added information on abundance and survival of the meroplankton in and around the Bay [26, 34, 38]. Some of this information was recently brought together in an evaluation of eutrophication status of Sevastopol Bay . However, data on overall meroplankton abundance rather than on individual taxa are still very scanty and relate rather to the neighbouring area of Sevastopol roadstead than Sevastopol Bay itself [24, 27]. Of the studies on the quantitative distribution of larvae in the wider Black Sea coastal waters and bays, the majority of them focus on Bivalvia [18, 25, 39], Polychaeta and Gastropoda [23, 28], and Cirripedia [3, 45].
Studies elsewhere on meroplankton have demonstrated the importance of seasonality and environmental variables on spatial structure and succession [5, 6] and long-term data sets are now
© E. V. Pavlova, V. V. Murina, R. B. Kemp, J. G. Wilson, V. P. Parchevsky, 2007
underpinning investigations into climate change [12, 31]. However, the influence of biological factors is less studied, although some work does suggest that meroplankton are relatively inefficient feeders  and are in turn readily taken by most predators . In the North Sea, there is some suggestion of top-down control by fisheries .
This study sets out the seasonal cycle of the population dynamics of the meroplankton with particular reference to the contamination status of the different compartments of Sevastopol Bay.
Materials and methods. Over many years of research  a carefully characterized set of sampling sites has evolved for the study of
Sevastopol Bay. For the purposes of this current study, zooplankton collections were taken at three sites in different areas of Sevastopol Bay (Figure 1): at the entrance (site 7, depth 14 m), at the head of the Bay (site 2, depth 10 - 15 m) and in South Bay (site 6, depth 7 - 10 m) which, as has been previously shown, differ in the degree of anthropogenic contamination, water circulation and physical-chemical characteristics. These earlier studies established that South Bay (site 6) was the most polluted while the area at the bay inlet (site 7) was the least polluted [14, 35]. For comparison, plankton hauls were taken at a reference site outside Sevastopol Bay (site 9, depth 15 m).
Fig. 1 Stations of meroplanktonic investigations in Sevastopol Bay 1998 - 1999
Рис. 1. Расположение станций исследования меропланктона в Севастопольской бухте в 1998 - 1999 гг.
From May 1998 to November 1999,
single monthly (with the exception of March 1999 due to bad weather) vertical hauls from 0 - 10 m or from the bottom to the surface were taken with a plankton net (150 цгп mesh, inlet diameter 36 cm). The collected plankton samples were immediately fixed on board during sampling by formalin bringing its concentration in the bottle to 4 %. After the lapse of 5 to 14 days of sampling, species identification, their abundance and differentiation the individuals into living and dead to estimate survival were carried on in the laboratory. The state of the chitin envelope, body 64 transparency and turgor, the intactness of bristles and appendages and the presence of the distinctive coiled structures in the muscles during their decomposition were the criteria used to establish the viability of the individual. The visual evaluation was checked with the dye method of B. G. Alexandrov and O.A. Ablov , which has been shown to give similar results . The number of living and dead (before fixation) organisms were determined for each species and for each size class. The abundance of cirripede and molluscan larvae and small polychaetes was estimated from replicate 3.0 ml sub-samples while
that of large polychaetes and decapod larvae was estimated from the whole sample. The biomass of the organisms was calculated according to . The general tendencies of the biomass' changes of larvae were evaluated. The biomass of the polychaetes and cirripedies were calculated by length in cube, where it was possible. Hydrophysical and hydrochemical data were obtained at the same time .
Canonical correlation, multiple regression and discriminant analysis were used to test the relationship between biological variables and environmental variables. Statistical analyses were performed according to [1, 11]. The variables were categorized into one of three groups: the 1st group comprised the biological variables of living biomass and the relative percentages of living and dead cirripede, polychaete and mollusk larvae, the 2nd group had the hydrophysical variables of temperature and salinity; and the 3rd group had the hydrochemical variables O2, PO42-, SiO32-, NO3-, NO2- and NH4+ concentrations.
Results. Over the period 1998 - 1999, 40
species, representing 32 families of pelagic larvae of the benthic invertebrates were found in Sevastopol Bay (Table 1).
Table 1 Taxonomic composition and maximal abundance (individuals-m-3) of meroplankton in Sevastopol Bay 1998 - 1999 at sites 2, 6 and 7 (see Fig. 1 for locations)
Табл. 1 Таксономический состав и максимальная численность (экз. м-3) меропланктона в Севастопольской бухте 1998 - 1999 гг. на ст. 2, 6 и 7 (расположение станций - на рис. 1)
Class, order, family, species
Microspio meznikowianus (Claparede, 1869)
Prionospio cirrifera Wirren, 1883
Nerine cirratulus (Delia Chaije, 1827)
Neanthes succinea Leuckart, 1847
Nereis zonata Malmgren, 1867
Nephthys hombergii Aud. Et M.-Edwards, 1834
Pholoe synophthalmica Claparede, 1868
Harmothoe reticulata Claparede, 1870
Mytilus galloprovincialis Lamarck, 1819
Mytilaster lineatus (Gmelin, 1790)
Polititapes aurea (Gmelin, 1790)
Teredo navalis Linne, 1758
Scapharca inaequivalvis (Bruguiere, 1789)
Bittium reticulatum (Costa, 1799)
Rissoa parva (Costa, 1779)
R. membranacea Adams, 1797
Table 1 (Contd)
Caecum elegans Perejaslavtseva, 1891 Hydrobiidae
Hydrobia acuta (Draparnaud, 1805) Muricidae
Rapana thomasiana Grosse, 1861 Turbonillidae
Parthenina terebellum (Philippi, 1844) Limapontiidae
Limapontia capitata (Mueller, (1773) Retusidae
Retusa truncatella (Locard, 1892) Haminoeidae
Haminoea navicula (Costa, 1778) Tergipedidae
Tergipes tergipes (Forskal, 1775) CRUSTACEA DECAPODA Calianassidae
Upogebia pusilla (Petagna, 1792) Xanthidae
Xantho poressa (Olivi, 1792) Rhithropanopeus harrisi tridentata (Maithland,1874) Porcellanidae
Pisidia longimana (Risso, 1815) Crangonidae
Crangon crangon Linne, 1758 Palaemonidae
Palaemon elegans Rathke, 1837 Alpheidae
Athanas nitescens Leach, 1814 Alpheus dentipes Guerin, 1832 Paguridae
Diogenes pugilator Roux, 1828 Grapsidae
Pachygrapsus marmoratus (Fabricius, 1793)
Balanus improvisus Darwin, 1854 Verrucidae
Verruca splengeri Darwin, 1854
Phoronis euxenicola Selys-Long., 1907
Botryllus schlosseri (Pallas, 1766)
Total number of species (families)_
288 2 1
34 28 4 16 4
80 5 2 12 18 2 13 1
432 192 2
200 220 2 16 24
The bulk of the larvae were polychaetes (10 species in 5 families), bivalves (5 species in 4
families), gastropods (11 species in 10 families) and decapods (11 species in 9 families) with only
two species (in 2 different families) of cirripedes. Among the rarities were the actinotroch (class Phoronidea) Phoronis euxinicola, the only species found in the Black Sea, as well as ascidian Botryllus schlosseri. The highest number of taxa (40 species, 32 families) was found at the bay entrance (site 7) followed by the top part of Sevastopol Bay (site 2; 31 species, 26 families) and the South Bay (site 6; 30 species, 25 families). Larvae of Balanus improvisus and Polydora sp. were abundant in the meroplankton of all the three regions as were those of Mytilus galloprovincialis, with the greatest abundance of all three species at site 2 at the head of the Bay. High abundances of
Caecum elegans and Upogebia pusilla larvae over the summer period were typical for South Bay. Nephthys hombergii and Pholoe synophtalmica larvae were rare and recorded only at site 7. At the same site there was a relatively rich decapod fauna of Alpheidae, Paguridae, and Grapsidae, among them Pachygrapsus marmoratus is listed in the Red Book of the Ukraine .
Figure 2 shows the annual cycle of diversity (number of species) and abundance (living individuals-m-3) in the different regions of Sevastopol Bay. For both measures 1999 seemed to be a more successful year with higher peaks sustained into the autumn months.
sm&* «1*1 ^sssi
Fig. 2. Meroplankton in Sevastopol Bay 1998 - 1999 at sites 2, 6 and 7: number of species (А) and abundance of individuals-m-3 (В) Рис. 2 Число видов (А) и численность, экз. м-3 (В) в меропланктоне Севастопольской бухты (1998 - 1999 гг., станции 2, 6 и 7)
The Shannon index (H', Fig. 3) follows a similar pattern to numbers of species (Fig. 2) but evenness (J = H'/Hmax) was relatively constant with the exception of November 1998, when both extremely low (site 7) and extremely high (sites 2, 6) values were seen. Then site 2 showed a very low evenness value, as well as a very low H in August 1999. However, in the same month,
4.0 3.5 3.0 2.5 2.0 1.5 1.0
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2
Морський екологічний журнал, № 2, Т. VI. 2007
neither the numbers of species nor individual abundance at site 2 were greatly different from those at other sites. The variation appears to be temporal rather than spatial, in that August 1999 saw a marked decline in all three diversity measures (species' number, H', J) compared to July and September 1999 while density of individuals showed much less of a fall (Figs 2, 3).
Fig. 3. Meroplankton in Sevastopol Bay 1998 -
1999 at sites 2, 6 and 7:
Shannon indexH', (А) and evenness J = H /Hmax, (В)
Рис 3. Меропланктон Севастопольской бухты в 1998 - 1999 гг.: индекс Шеннона H', (А) и индекс равномерности распределения
<COOZq^ u-s<s т ^ < в о z 1998 1999
The seasonal dynamics of the abundance of the dominant meroplankton taxa are given in Fig. 4 and they show clearly the greater numbers and bimodal peaks in 1999. The maximum density of cirripede larvae was recorded in June 1998, and again in May and in August 1999. These barnacle larvae were found throughout the year, but in extremely low numbers in January-February. In 1999, the highest density was recorded in the top part of the bay at site 2, whereas site 6 had the highest densities in 1998. Relatively low numbers of both polychaete and mollusk larvae were found in 1998 compared to the following year, when peak numbers were found at all sites, although with some variability in actual numbers and in the timings of the peaks (Fig. 4).
10000 1000 100
-site 2 -site 6
70 60 50
site 7 40 30
E 10 ri> E
і—site 2 »— site 6 •— site 7
V VII IX XI
V VII IX XI
v vii ix xi
iii v vii ix xi
10000 1000 100
V VII IX XI
III V VII IX XI
v vii ix xi
iii v vii ix xi
10000 1000 100 10
V VII IX XI I III V VII IX XI
Fig. 4. Seasonal dynamics of abundance (individuals-m-3) of meroplankton in Sevastopol Bay May (V) 1998 - December (XII) 1999 at sites 2, 6 and 7: A - Cirripedia, B - Polychaeta, C - Mollusca Рис.4. Сезонная динамика численности (экзм-3) меропланктона в Севастопольской бухте за период май 1998 - декабрь 1999 гг. на станциях 2, 6 и 7: A - Cirripedia , B - Polychaeta, C - Cirripedia, B
v vii ix xi
iii v vii ix xi
Fig. 5. Seasonal dynamics of biomass (mgm-3) of meroplankton in Sevastopol Bay May (V) 1998 -December (XII) 1999 at sites 2, 6 and 7: A - Cirripedia, B - Polychaeta, C - Mollusca
Рис.5. Сезонная динамика биомассы (мгм-3) меропланктона в Севастопольской Бухте за период с мая 1998 по декабрь 1999 г. на станциях 2, 6 и 7: A -- Polychaeta, C - Mollusca
Морський екологічний журнал, № 2, Т. VI. 2007
Polychaete larvae were not found at all in the winter months from December to February, with the exception of one single individual (Harmothoe sp.) in February, while mollusk larvae peaked earliest in April 1999 at site 2. Decapod larvae were found only sporadically with little discernable pattern, and overall the highest numbers were found at site 2 at the top of the Bay.