Spatial and temporal distribution of Temoridae ...

Cah. Biol. Mar. (2018) 59 : 205-215 DOI: 10.21411/CBM.A.A9061453

Spatial and temporal distribution of Temoridae species in coastal waters of the Southeast Adriatic (NE Mediterranean) Vera VUKANIĆ1, Dušan VUKANIĆ2, Miloš FILIPOVIĆ3, Nataša GLIŠOVIĆ4 and Murat SEZGIN5 (1) Department of Biomedical Sciences, Faculty of Biology, State University of Novi Pazar, Serbia (2) Institute of Marine Biology Kotor, University of Montenegro, Montenegro (3) Department of Chemical – Technological sciences, State Unuversity of Novi Pazar, Serbia (4) Department of Mathematical Sciences, Faculty of Mathematical Science, State University of Novi Pazar, Serbia (5) Marine Biology and Ecology Department, Faculty of Fisheries, Sinop University, Turkey Corresponding author: [email protected]

Abstract: This study investigated the horizontal distribution and abundance of copepod species Temora stylifera (Dana, 1849), Temoropia mayumbaensis T. Scott, 1894, Temora longicornis (O.F. Müler, 1792) and Temorites brevis G.O. Sars, 1785 in the surface water of the southeastern Adriatic Sea during 2008. For the first time, the species T. longicornis was registered in high abundance in the southeastern Adriatic Sea in the zone of hydrological discontinuity. The species belongs to the group of copepods that are dominant in the North Adriatic Sea. The deep-sea species T. mayumbaensis is just present in deep waters of the South Adriatic Pit. The presence of T. stylifera was constant in the plankton community of the studied area, whereas T. brevis was registered intermittently in individual samples.

Résumé : Distribution spatiale et temporelle des espèces de Temoridae des côtes sud orientales de l’Adriatique (Méditerranée nord orientale). La distribution horizontale et l’abondance des copépodes Temora stylifera (Dana, 1849), Temoropia mayumbaensis T. Scott, 1894, Temora longicornis (O.F. Müler, 1792) et Temorites brevis G.O. Sars, 1785 ont été estimées dans les eaux de surface sud orientales de la Mer Adriatique en 2008. Pour la première fois, T. longicornis a été récoltée en grande quantité au niveau de la zone de discontinuité hydrologique. L’espèce appartient au groupe de copépodes dominant la partie septentrionale de l’Adriatique. L’espèce d’eau profonde T. mayumbaensis n’étend pas sa distribution horizontale à partir de la fosse sud Adriatique. T. stylifera est présente en permanence dans la communauté planctonique de la zone étudiée alors que T. brevis n’a été récoltée que de façon intermittente dans quelques échantillons. Keywords: Temoridae l South Adriatic Sea l Bay of Boka Kotorska l Copepoda

Reçu le 11 janvier 2017 ; accepté après révision le 24 octobre 2017. Received 11 January 2017; accepted in revised form 24 October 2017.

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Introduction

TEMORIDAE SPECIES IN THE SE ADRIATIC

The investigated area of the South Adriatic Sea differs ecologically from the coastal waters with characteristic groups of islands in the North and Middle Adriatic Sea, which is reflected on temporal and spatial distribution of zooplankton species. The Adriatic Sea interacts with the main body of the Mediterranean Sea through the inflow of the Levantine Intermediate Water and Ionian Sea surface water along the eastern border of the Adriatic Sea. A relatively wide area of continental shelf 100 to 220 m deep stretches in front of the mouth of the Bay of Boka Kotorska, extending southwest into the South Adriatic Pit. The entire Adriatic Sea, and especially its southern part, is under the influence of active interbasin exchange of water masses via the submarine Strait of Otranto, which is 741 m deep (Buljan, 1953). The rivers Bojana and Drim affect the hydrological regime of the open waters of the South Adriatic Sea. The investigated area is characterized by two different oceanographic events: a) winter, typified by the prevalence of dynamic processes of interbasin exchange between the Adriatic and Ionian Sea, and b) summer, defined by freshwater inflow from the Bojana and Drim Rivers. During these investigations, we recoded four species of Copepoda from the family Temoridae: Temora stylifera, Temoropia mayumbaensis and two very rare species, Temora longicornis and Temorites brevis. Two species were present in the Bay of Boka Kotorska: T. stylifera, which is a characteristic form of coastal and epipelagic waters, and T. longicornis, an outstanding representative of the neritic area, especially estuary waters of the North Adriatic (Hure et al., 1980). Onofri (1984) cited that T. longicornis was the most numerous at three inner stations in the Bay of Mali Ston (Croatian), comprising 88.3% of the total number of encountered specimens compared to outer stations where it included only 11.7% of total specimens. Vukanić (1979) registered this species for the first time in the Bay of Boka Kotorska in the proximity of Kotor. In Kaštela Bay (Croatian) it was encountered sporadically in a very small number or as individual specimens by Regner (1976). The species T. longicornis was cited in earlier papers as a characteristic species of the northwestern coast of the Adriatic, extending southward to the Neretva Delta (Gamulin, 1939; Hure & Scotto di Carlo, 1969; Hure et al., 1979). Hure & Kršinić (1998) reported that, in spring and summer, the species is transported by sea currents in high numbers from its primary habitat in the North Adriatic, invading almost the entire Middle Adriatic along the western coastal belt down to the Strait of Otranto. The species T. stylifera is present in the entire Adriatic, whereas the species T. mayumbaensis exhibits no seasonal changes in horizontal distribution (Hure & Kršinić, 1998; Vukanić, 2002). The aims of this paper are: to present an overview of

the spatial and temporal distribution of species of the family Temoridae in the southeastern Adriatic Sea and the Bay of Boka Kotorska, to elucidate the role played by the environmental factors on their annual cycles, and to explain the high abundance of T. longicornis in southeastern Adriatic.

Matherial and Method

Study area

The sampling stations were located in the southeastern Adriatic Sea (Fig. 1). The Bay of Boka Kotorska penetrates deeply into the land (about 25 km) and it is under a direct influence of pelagic waters through its outer bays, the Bay of Herceg Novi and the Bay of Tivat. Inner part of the Bay of Boka Kotorska, composed of the Bay of Kotor and the Bay of Risan, communicate with the outer part, the Bay of Tivat and the Bay of Herceg Novi, through the 340-m-wide strait Verige, whereas the main transversal entrance into the Bay of Boka Kotorska facing the open sea is 950 m wide (Cape Oštra-Cape Arza). The study area of the South Adriatic Sea extends from the Cape Oštra to the estuary of the Bojana River, on the north it is bordered by shallower

Figure 1. Map of sampling area in southern Adriatic (ZHD: the zone of hydrological discontinuity).

V. VUKANIĆ, D. VUKANIĆ, M. FILIPOVIĆ, N. GLIŠOVIĆ, M. SEZGIN

parts of the Adriatic coastal area (150 to 220 m deep), and to the south, it extends into a steep submarine continental shelf, descending towards the South Adriatic Pit for some 40 nautical miles from the coast into the open sea and to a depth of 1330 m. We investigated the Bay of Boka Kotorska, estuary of the River Bojana, and the epipelagic and deep waters of the southeastern Adriatic Sea. Plankton and hydrography samples at the Bay of Boka Kotorska were collected at three stations: Kotor Bay (P1, 0-30 m depth), Tivat Bay (P2, 0-30 m depth), and Herceg Novi Bay (P3, 0-50 m depth). In addition, the samples were collected 10 nautical miles offshore from the entrance to the Bay of Boka Kotorska at a maximum depth of 220 m (P6), 5 nautical miles offshore (P7, 100 m depth), and 25 nautical miles offshore (P8, 1000 m depth) located in the South Adriatic Pit. Two additional stations were located in the estuary of the river Bojana (P9, 8 m depth) and 15 nautical miles offshore in front of the estuary (P10, 150 m depth). The area of the southeastern Adriatic is strongly influenced by the northwestern inflow of an oligotrophic current originating in the eastern Mediterranean (Zore-Armada, 1969; Orlić et al., 1992; Batistić et al., 2007).

Sampling and laboratory procedures

Plankton samples were collected in seasonal series during cruises in 2008: 15 January-13 March, 22 May-30 May, 24 June-15 July, and 17 October-6 November. Zooplankton was collected using plankton nets of Nansen type with a diameter of 0.57 cm and a length of 250 cm for vertical hauls and with a diameter of 1 m and a length of 3 m for horizontal catches. The net mesh size was 200 µm and 150 µm for vertical catches and 250 µm for horizontal towing. Zooplankton sampling in Boka Kotorska Bay was conducted using the net with meshes of 150 µm. The trawling speed for vertical catches was 0.5 m.s-1. The horizontal draws implemented with neat using stair-like method segmented increment in duration of 30 minutes between them. We analysed a total of 32 samples, one sample per station, for each season. Samples were preserved in 2.5% formaldehyde. Qualitative analysis of zooplankton was conducted by partial counting of 1/25 of each catch. Taxonomic identification and counting of individuals were performed with Zeiss stereomicroscope at 25× and 40× magnifications. Abundance of all Copepoda was presented as the number of specimens per square meter (ind.m-2). Taxonomic identification was determined following Rose (1933) and Tregouboff & Rose (1957). At the time of zooplankton sample collection, the basic hydrographic factors, temperature (T°C) and salinity, were also measured using a CDT multiline P4 (SEA Bird Electronics Inc., Bellevue, WA, USA). Water samples were taken with 5-L Nansen bottles at 0, 5, 10, 20, 30, 100, 150, and 200 m depths. Dissolved oxygen was determined by

207

the Winkler method, and oxygen saturation was calculated from solubility of oxygen in seawater as a function of temperature and salinity (Weiss, 1970). The relationship between groups, species, and environmental parameters was tested using the Spearman′s rank correlation coefficient. Unlike the Pearson’s coefficient of correlation, which assumes linear relationships, Spearman’s rank correlation coefficient is applied for both linear and nonlinear relationships and can be used for smaller samples (n < 35). Spearman’s coefficient with ρs ranks at the population level was determined based on its value calculated for the sample rs, (1) where is x is the first parameter, y the other parameter, and the arithmetic means. The species of a particular group was determined according to their contribution to the total number of specimens (relative abundance > 10%). Statistical analyses were performed using the SPSS software package (IBM Corp., Armonk, NY, USA).

Results and Discussion

Environmental conditions

The mean annual seawater temperature measured during 2008 ranged from 14.25°C (P3) to 17.5°C (P7). The higest and lowest temperature values were observed in summer and winter, respectively. Salinity values fluctuated between 33.65 and 38.51. The lowest salinity was observed in station P1 in winter, while higest salinity was observed at station P7 in summer. Oxygen O2 values reached their highest levels throughout the year (Table 1). Sea temperature in the Bay of Boka Kotorska (P1, P2, Table 1. The mean annual hydological sea parameters at sampling stations in the Bay of Boka Kotorska (P1-P3) and the South Adriatic Sea (P6-P10). Stations T°C Salinity O2% P1

16.45

31.97

P2

14.25

33.65

P6

16.09

37.17

P8

17.02

P10

17.02

P3 P7 P9

16.82 17.5

17.27

104.6

pH 8.4

102.6 8.17

Transparency Depth (Secchi) (m) 7.9 30 9.2

30

100.0 8.22

22.0

200

38.51

102.0 8.23

22.0

200

38.49

102.0 8.24

22.0

150

36.18

101.61 8.18

38.38

101.0 8.24

34.7

100.6 8.21

10.0 -

2.3

30

100 8

208


Figure 2. Temperature oscillations (°C) on Bay of Boka Kotorska during 2008.

P3) showed pronounced seasonal oscillations, especially in the surface strata and during the summer season when the inflow of fresh waters is decreased and the air temperature is high (Fig. 2). The maximum surface temperature in the bay usually occurs in July or August and ranges from 25.5 to 29.9°C in its shallower part (Fig. 2). It gradually declines toward the open sea and with increasing depth. The temperature maximums in the middle of individual bays were as follows: 25.80°C in Kotor Bay (P1), 25.50°C in Tivat Bay (P2), and 24.80°C in Herceg Novi Bay (P3) (Fig. 2). The maximal temperatures of strata in the middle of water columns and close to the sea bottom were registered in August (23.20°C) and September (23.65°C). The lowest temperature of surface sea strata in the Bay of Boka Kotorska was registered in February (7.00°C). The annual gradient of surface strata temperature was 16.50°C. The minimal annual temperature near the sea bottom was registered in February: 12.50°C in Kotor Bay (P1), 12.00°C Tivat Bay (P2), and 14.00°C in Herceg Novi Bay (P3). The annual gradient in strata near the sea bottom ranged from 4.60°C in the Bay of Herceg Novi (P3) to 5.86°C in the Bay of Kotor (P1). Homeothermy was not observed and seasonal temperature oscillations in the bay did not demonstrate regular succession known for the pelagic waters of the Adriatic. The high temperature gradients measured in the Bay of Boka Kotorska indicated that the biotope is of subtropical type. The area of pelagic waters investigated in this study is situated in the zone of interbasin exchange of water masses between the Adriatic and Ionian Sea and the hydrological regime of the rivers Bojana and Drim. Moreover, studies have confirmed that the Adriatic Sea is a dilution basin (a gain of 1.14 ± 0.20 m per year from precipitation and river runoff is greater than evaporation). At the same time the Adriatic Sea imports (it has been computed that there is a surface heat loss of 19-22 W m-2 per year); hence salt and heat balances are maintained through the water exchanges across the Otranto Straits, where relatively fresh and cold waters leave the Adriatic basin and warmer, saltier waters enter from the Ionian Sea in the Adriatic Sea (Russo & Artegiani, 1996). Temperature

of southern coastal waters at 12 to 13°C in winter are relatively high, and in summer they range from 23 to 27°C (Fig. 3). In winter, isothermy dominates throughout the entire water column, whereas in spring, warming up of the surface strata produces a thermocline between 10 and 30 m depths, which is pronounced the most in summer. The temperature of the entire water column in the shallow section of the sea in the estuary of the river Bojana in summer is between 7.19 and 22°C and remains lower than the temperature of the surrounding sea. Fresh waters drainage basins of the Bojana and Drim Rivers increase temperature stratification in coastal waters. Summer stabilization of the temperature decreases the vertical mixing of water masses and there occurs a partial isolation between surface and deeper strata. The maximal and minimal temperatures of surface sea strata were registered in July (26.80°C) and February (13.80°C), respectively; the maximum and minimum temperatures at a depth of 100 m were 19.60°C and 13.17°C, respectively (Fig. 3). The amplitude of surface strata was 13.00°C. Horizontal distribution of surface temperatures in the Adriatic is mostly caused by seasonal periods, whereas multiannual temperature oscillations are caused by the influence of the Mediterranean on the Adriatic. The rather high winter temperatures of investigated area reported herein confirm that in this season the open South Adriatic is warmer than the Middle and North Adriatic. This corroborates the results by Russo & Artegiani (1996) who classified water mases of the Adriatic Sea as Southern Adriatic Surface Water (SAdSW) with water temperatures in winter being somewhat lower than 13.5°C. The salinity in the Bay of Boka Kotorska is strongly influenced by freshwater inflow from land, especially in its inner part (Kotor Bay [P1] and Risan Bay). The salinity of the surface sea waters in the bay varies depending on the quantity of freshwater inflow. The average salinity values varied by individual bays: in the Bay of Kotor (P1) it ranged from 8.02 at the sea surface in February to 38.39 on the sea bottom in June. In the Bay of Tivat (P2), salinity at the surface was 22.44 in March and 38.58 psu on the sea bottom in May. In the Bay of Herceg Novi, salinity ranged


209

Figure 3. Temperature oscillations (°C) on South Adriatic during 2008.

from 30.01 at the surface in February to 38.48 on the sea bottom in May (Fig. 4). The maximal values of surface salinity were registered in August: 30.44 in the Bay of Kotor (P1), 34.43 in the Bay of Tivat (P2), and 35.95 in the Bay of Herceg Novi (P3) (Fig. 4). In former studies, the maximum salinity of surface strata exceeded 38.00 (Vukanić, 1971 & 2004). The lower values of surface salinity reported herein are caused by abundant rainfalls that preceded the measurements. The impact of the freshwater inflow was more pronounced in the inner part of the bay (P1) where the minimal salinity values during the year was from 7.75 to 8.02 with a very high amplitude of salinity (28.92). The minimal values of salinity on the sea bottom were measured in the Bay of Kotor (P1) (28.00), and the maximal values were detected in the Bay of Herceg

Novi (P3) (38.59), with amplitude of 10.59 (Fig. 4). The salinity in Boka Kotorska Bay was reduced during the fall and winter owing to increased inflow of freshwater from land. In offshore waters of the South Adriatic more intense salinity oscillations of surface strata were observed at the stations exposed to freshwater inflow of the Bojana and Drim rivers (P7, P9 & P10). In that zone of the sea, the salinity ranged from 37.10 to 38.30 and it was greatly affected by the surface currents that help the circulation of the fresh water. At the typical epipelagic stations (P6 & P8), the mean salinity value varied between 38.48 and 38.60 (Fig. 5). The salinity at the stations in epipelagic waters of the South Adriatic was affected by the dynamic processes of interbasin exchange between the Adriatic and Ionian Sea

Figure 4. Oscillation of the salinity on Bay of Boka Kotorska during 2008.

210


Figure 5. Oscillation of the salinity on South Adriatic during 2008.

and the freshwater masses of various intensity from the Bojana and Drim rivers depending on the season. We recorded the maximal salinity of 39.00 in October at a deep epipelagic station (P8) The minimal salinity of surface waters was registered at the stations closer to the coast in May: 20.00 (P9), 37.20 (P7), 37.50 (P10), and 38.10 (P8) (Fig. 5). The salinity in epipelagic waters and toward the deeper strata of the sea below 10 m depth ranged from 38.22 to 38.82 (Fig. 5). A strong vertical salinity gradient was established from April to August, at the time when the thermocline is formed. The relatively high salinity in the South Adriatic results from the significant ingress of saltier water from the eastern Mediterranean in the fall and winter seasons, which is positively reflected on organic production in that sea (Buljan, 1964). In a relatively spacious area of epipelagic waters of the southeastern Adriatic, seasonal impacts of various water masses are present, in particular those by deep sea masses with oligotrophic properties (Buljan, 1964) along with the currents from the Mediterranean and fresh waters. Škrivanić & Vučak (1983) reported that during the spring maximum levels of the rivers along the MontenegrinAlbanian coast and the coast of Puglia (Italy), the entire area of the South Adriatic is bridged in transversal direction by these fresh water inflows. Those transversal currents actuate the forming of the so-called zone of hydrological

discontinuity (ZDH) (Fig. 1), which is based on thermocline structure of that profile and is reflected on the distribution and abundance of the species in the zooplankton.

Seasonal characteristics of species from the family Temoridae

Four species from the family Temoridae were identified: Temora stylifera, Temoropia mayumbaensis and two very rare species Temora longicornis and Temoris brevis. T. brevis was registered only as individual specimens in summer at stations located in open and deeper sea (P6 & P8). T. longicornis is a typical estuarine neritic species adapted to sea waters with lower salinity levels and lower temperatures. It occupies the depths of up to 50 m and belongs to the group of dominant copepods in the southwestern Adriatic Sea. We detected T. longicornis in the Bay of Boka Kotorska, at the station P2 in the Bay of Tivat in summer (0.10%) and winter (0.01%) and at the station P3 in the Bay of Herceg Novi in spring (0.10%) and summer (0.06%). It was registered within the temperature range of 15.44-22.79°C and salinity range of 27.57-38.44. In the deep waters of the South Adriatic, it was registered at the stations P6 in summer (0.04%), P7 in summer (0.70%) and autumn (0.80%), P8 in winter (0.40%), and P10 in winter (9.90%). In


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Table 2. Seasonal medium values of quantity (ind.m-2) and relative abundance of family Temoridae species during the study at sampling stations in the Bay of Boka Kotorska (P1-P3) and the South Adriatic Sea (P6-P10). r : rare species. Seasons Stations Temora stylifera Copepoda

Temora stylifera Temora longicornis Copepoda Temora stylifera Temora longicornis Copepoda Temora stylifera Temora longicornis Copepoda Temora stylifera Temora longicornis Copepoda

Spring

%

Summer

34 293200

0.01

r 354200

r

%

Autumn 100 295800

141500

233 266 242400

0.09 0.10

1133 34 336300

100 98400

0.10

1200 200 330500

0.36 0.06

8900

430

1.54

416 8 20795

2.01 0.04

500 100 14406

3.50 0.70

27904 400

2.73

14662

30242 3200 100 12377

86

0.32

387

0.97

5 26707

0.01

877 39617

2.21

Temora stylifera Copepoda

114 18628

0.61

267 19541

1.37

229 815

Temora stylifera Temora longicornis Copepoda

7600

8.70

800

9.30

1400

8620

pelagic waters of the South Adriatic, the species was registered in the temperature range of 13.82-22.98°C and salinity range of 37.01-38.53. Taking into account that this is a boreal copepod, its occurrence in winter season at the station P10 (0-150 m) is unusual. We assume that it was brought by a current of lower salinity via the ZHD from the western part of South Adriatic. Vukanić (1979) registered species T. longicornis in the Bay of Kotor as an adult form in small number with a considerable relatively abundance of copepodites. This species, which is typical for the southwestern coast of the Adriatic and had been formerly registered within the temperature range of 14.6-17.5°C and salinity range of 36.2-38.1 (Gamulin, 1939; Hure & Scotto di Carlo, 1969; Hure et al., 1979), along the southeastern coast

P2

P3

Winter

%

0.03

134 228600

0.05

268 4551200

0.005

0.33 0.01

1300 r 501700

0.26

2666 300 1221900

0.21 0.03

1.65

5800 r 438000

1.32

15900 300 1406400

1.13 0.02

200

0.50

1746 8 119367

1.50 0.007

11.70

6900 200 65380

10.56 0.30

0.09 0.40

26081

541 100 882 99314

0.55 0.10 0.90

913

610 39897

1.53

8540 1600 130054

6.60 1.23

539500 P6 700 2.31

Temora stylifera Temora longicornis Temoropia mayumbaensis Copepoda

87715

P1

%

44 6909

17560

P7

P8

P9 P10

40426 25.86 0.80 0.63

28.09 7.97

2800 23935 24 100

1600 16159

9.90

Total

%

of the Adriatic has been known only south of Neretva’s water way. Vukanić (1975) found three specimens and Hure & Scotto di Carlo (1969) reported two specimens in open waters of the South Adriatic. According to Vukanić (1979), this species was present in greater frequency and abundance in the Bay of Kotor in July 1975 compared to the species T. stylifera after blooming of Dinoflagellate and cooling of the biotope under the influence of northern winds. Vukanić (2007) registered T. longicornis during the winter–spring period mainly at the stations closer to the open sea in outer bays, Tivat and Herceg Novi. Temora stylifera is a surface-dwelling, tropic species present in the plankton of the Bay of Boka Kotorska throughout the entire year, except for the inner Bay of

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Figure 6. Temora stylifera. Seasonal distribution in the studied region in the South Adriatic Sea.

Kotor at station P1, where it is nearly absent from the middle of winter to the end of spring. Its abundance in the inner part of the Bay of Boka Kotorska increased from June to September. At the station P1 in the Bay of Kotor, its abundance was 0.01% in spring, 0.003% in autumn, and 0.05% in winter (Fig. 6). In the outer Bay of Tivat (P2), its abundance was 0.09% in summer, 0.33% in autumn, and 0.26% in winter. In the Bay of Herceg Novi (P3), its abundance increased from 0.36% in the middle of summer

to 1.65% by the end of autumn and decreased to 1.32% in winter (Fig. 6). The species was present in the temperature range of 12.55-22.79°C and salinity range of 11.56-38.44. The period of higher occurrence and greater frequency at the open sea (P6-P10) spanned from the middle of summer to the middle of autumn. Since this is a tropical species, the occurrence of abundance maximum in warm part of the year was expected. At these stations, the species was registered in the temperature range of 13.82-23.65°C and

Figure 7. Temora stylifera. Day-night migration in the South Adriatic.


salinity range of 19.57-38.90. The relative abundance of the species T. stylifera ranged from 0.005% in the Bay of Kotor (P1) to 1.50% in the Bay of Herceg Novi and from 6.6% (P10) to 10.56% (P7) in the open sea. It occurs from the surface to 150 m depth, with annual mean maximum numbers at depths below 25 m. At depths below 50 m, it was detected only as individual specimens and day catches (Fig. 7). Hure (1961) registered it throughout the entire year in the surface stratum, but below 30 m only as individual specimens. Moore (1949) reported it from 0 m to 400 m depth and Pesta (1920) from 0 to 100 m depth. Seasonal and day-night migration are poorly defined (Fig. 7). The mean daily migration was 40 m, and day–night distribution was 20 m. Similar data for the Adriatic Sea were also reported by other authors: Pesta (1920), Gamulin (1938, 1939 & 1979), Hure (1955), Hure & Scotto di Carlo (1969), Vukanić (1971, 1975 & 1979), Hure & Kršinić (1998), Vukanić (2004, 2007 & 2012), Vukanić & Vukanić (2003, 2004 & 2006). T. stylifera has a wide distribution in the Mediterranean. Mazza (1962 & 1966) and Mazzocchi & Di Capua (2010) reported that, along with the species of the genus Clausocalanus Giesbrecht, 1888 and Paracalanus parvus (Claus, 1863), T. stylifera is one of the most frequent and most numerous copepods of the western Mediterranean. Temoropia mayumbaensis is a species that belongs to

213

deep water fauna of Copepoda. The species has a weak vertical migration, and day-night migration has an inverse course (Vukanić, 2002). It was found only in deep waters of the South Adriatic at the station P8 (0-900 m); its abundance in spring was 0.01%, whereas in the summer in August, it increased to 2.21% especially in strata below 280 m. The relative abundance of the species T. mayumbaensis was 0.90% in relation to total Copepoda. Seasonal migration was not detected, whereas weak day-night migration was registered in August. The mean daily vertical distribution was 620 m, and day-night vertical distribution was 150 m (Fig. 8). Hure & Scotto di Carlo (1969) registered the maximal occurrence of this species during spring and in October for the Adriatic, whereas it was rare in the Bay of Naples (Italy). Pavlova (1966) reported it at depths of 300 to 800 m in the Aegean and Ionian Sea, Levantes and the Adriatic Sea, and Vukanić (2002) registered it in the strata below 500 m in the South Adriatic. Scotto di Carlo et al. (1984) found it in great abundance in the Tyrrhenian Sea in sea strata between 400 and 2000 m. The results of the statistical analysis of Spearman′s rank correlation coefficient have demonstrated the existence of strong connections between the temperature and the total number of Copepoda, as well as between the individual species and the total number of Copepoda (Tables 3 & 4). In the Bay of Boka Kotorska, the correlation among the three stations P1, P2 and P3 is presented in Table 3. High correlation was detected between: T. stylifera and Copepoda in the Bay of Tivat (P3) and T. stylifera and Copepoda in the Bay of Herceg Novi (P3). We registered a positive significant correlation between T. stylifera and total Copepoda in the Bay of Tivat (P2) and in the Bay of Herceg Novi (P3); these results were expected given the similarity of ecological conditions of the sea in those bays. Table 3. Spearman’s rank correlation coefficient between different taxa and environmental variables in the stations of the Bay of Boka Kotorska.

Figure 8. Temorpia mayumbaensis. Day-night vertical migration in the South Adriatic.

Taxa/Stations P1-Kotor Temora stylifera Copepoda P2-Tivat Temora stylifera Temora longicornis Copepoda P3-Herceg Novi Temora stylifera Temora longicornis Copepoda **P < 0.01

Temperature

Salinity

-0.800 1.000**

-0.800 0.400

-0.400 0.800 -0.400

-0.600 0.200 -0.600

0.000 0.400 0.000

0.400 0.200 0.400


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Table 4. Spearman’s rank correlation coefficients between different taxa and environmental variables in the stations of the southeastern Adriatic. Taxa/Stations P6 Temora stylifera Temora longicornis Copepoda P7 Temora stylifera Temora longicornis Copepoda P9 Temora stylifera Copepoda P10 Temora stylifera Temora longicornis Copepoda *P