Ecological health analysis of Caspian marine environment based on the diversity and distribution pattern of meiofauna in the Mazandaran Province, Caspian Sea

Biodiversity and distribution of benthic meiofauna in the sediments of the Southern Caspian Sea (Mazandaran) was studied in order to introducing and determining of their relationship with the environmental factors. From 12 stations (ranging in depths 5, 10, 20 and 50 meters), sediment samples were gathered in 6 months (2012). Environmental factors of water near the bottom including temperature, salinity, dissolved oxygen and pH were measured during sampling with CTD and grain size and total organic matter percentage and calcium carbonate were measured in laboratory. In different months, the average water temperature (9.52-23.93), dissolved oxygen (7.71-10.53 mg/L), salinity (10.57±0/07 and 10.75±0/04 ppt), pH (7.44±0/29 and 7.41±0/22), EC (17.97±0/12 and 18.30±0/04μs/cm2), TDS (8.92±0/04 and 9.14±0/02 mg/L), total organic matter (5.83±1/43 and 6.25±0/97%) and calcium carbonate (2.36±0/36 and 1.68±0/19%) were measured respectively. Structure of the sediment samples mostly consisted of fine sand; very fine sand, silt and clay. From the 4 group animals (Foraminifera, Crustacea, Worms and Mollusca), there were identified 40species belong to 29 genera of 25 families. The cosmopolitan foraminifer, Ammonia beccarii caspica, was common in all sampling stations. Result showed that depth was important factor on distribution of meiofauna. Most density of foraminifera and crustacean was observed in depth of 20m and for mollusca and worms observed in 5m. Shannon diversity index decreased with depth that showed in shallow water diversity was higher than deep water. Mean of maximum and minimum Shannon index was obsorvers in depth of 5m and 50 m that was measured in order 0.93 and 0.43. Account of Shannon index showed that this area is under pressure. Account of peioleo index showed distribution in this area was not steady.

Age model and ostracod countings from IODP Site 306-U1314

We present a detailed study of glacial/interglacial deep sea benthic ostracod assemblage variability at IODP Site U1314 (subpolar North Atlantic) in relation to the history of ice-rafting events and changes in deep ocean circulation over the past 170 ky. Our records of ostracod diversity, abundance and dissolution and sediment properties (IRD and CaCO3) show an excellent correspondence to high amplitude orbital and millennial variability observed in the climate records (d13C and d18O) from neighboring deep water sites, suggesting that the benthic meiofauna fluctuates synchronously with the prevailing oceanographic conditions (surface ocean conditions, deep ocean circulation and water temperature and food flux). Krithe (dominant), Argilloecia and Cytheropteron are the most abundant and diverse genera in association with Rockallia enigmatica. Three ostracod assemblages are recognized. The genera Pennyella, Argilloecia, Pelecocythere, Ambocythere, Pseudobosquetina, Bradleya and Nannocythere are associated with interglacials and interstadials, and possibly reflect increased flux of food to the sediments and more vigorous NADW formation. A transitional assemblage composed of species of Cytheropteron, Xestoleberis and Eucythere is restricted to climatic transitions and indicate moderate environmental conditions and seasonal productivity. A glacial/stadial assemblage is characterized by a temporal predominance of either intermediate-depth and shallow water Arctic/subarctic species (belonging to Cytheropteron, Polycope, Pedicythere, Swainocythere, Cluthia, Heterocyprideis, Elofsonella and Finmarchinella) or abyssal North Atlantic ostracods (Bythocythere, Dutoitella, Bathycythere and Bythocypris). The influx of high latitude taxa can be partially explained by ice-rafting, but may also represent a shift of the location of intermediate and deep water convection to the area south of Iceland. Therefore the combination of species characteristic of different watermasses during glacials may reflect shifts in the influence of high nutrient southern source water (e.g. AABW) vs. low nutrient GNAIW during glacials.

Effects of Lyngbya majuscula (Cyanophycea) blooms on sediment nutrients and meiofaunal assemblages in seagrass beds in Moreton Bay, Australia

Blooms of Lyngbya majuscula have been increasingly recorded in the waters of Moreton Bay, on the south-east coast of Queensland, Australia. The influences of these blooms on sediment infauna and the implications for sediment biogeochemical processes was studied. Sediment samples were taken from Moreton Bay banks during and after the bloom season. The deposition of L. majuscula seems to be responsible for the higher total Kjedahl nitrogen (TKN) concentrations measured during the bloom period. Total organic carbon (TOC) concentrations did not change. Lyngbya majuscula blooms had a marked influence on the meiobenthos. Nematodes, copepods and polychaetes were the most abundant groups of meiofauna, and the bloom produced a decrease in the abundance and a change in the sediment depth distribution of these organisms. The distribution of nematodes, copepods and polychaetes in sediment became shallower. Further, the bloom did not affect the abundance and distribution of polychaetes as strongly as it did copepods and nematodes. The changes observed in the distribution of meiofauna in the sediment during the bloom period indicate that L. majuscula produces oxygen depletion in sediments, and that different fauna seem to be affected to different degrees.

Sedimentary archives of climate and sea-level changes during the Holocene in the Rhone prodelta (NW Mediterranean Sea)

A 7.38 m-long sediment core was collected from the eastern part of the Rhone prodelta (NW Mediterranean) at 67 m water depth. A multi-proxy study (sedimentary facies, benthic foraminifera and ostracods, clay mineralogy, and major elements from XRF) provides a multi-decadal to century-scale record of climate and sea-level changes during the Holocene. The early Holocene is marked by alternative silt and clay layers interpreted as distal tempestites deposited in a context of rising sea level. This interval contains shallow infra-littoral benthic meiofauna (e.g. Pontocythere elongata, Elphidium spp., Quinqueloculina lata) and formed between ca. 20 and 50 m water depth. The middle Holocene (ca. 8.3 to 4.5 ka cal. BP), is characterized, at the core site, by a period of sediment starvation (accumulation rate of ca. 0.01 cm yr−1) resulting from the maximum landward shift of the shoreline and the Rhone outlet(s). From a sequence stratigraphic point of view, this condensed interval, about 35 cm-thick, is a Maximum Flooding Surface that can be identified on seismic profiles as the transition between delta retrogradation and delta progradation. It is marked by very distinct changes in all proxy records. Following the stabilization of the global sea level, the late Holocene is marked by the establishment of prodeltaic conditions at the core site, as shown by the lithofacies and by the presence of benthic meiofauna typical of the modern Rhone prodelta (e.g. Valvulineria bradyana, Cassidulina carinata, Bulimina marginata). Several periods of increased fluvial discharge are also emphasized by the presence of species commonly found in brackish and shallow water environments (e.g. Leptocythere). Some of these periods correspond to the multi-decadal to centennial late Holocene humid periods recognized in Europe (i.e. the 2.8 ka event and the Little Ice Age). Two other periods of increased runoffs at ca. 1.3 and 1.1 ka cal. BP are recognized, and are likely to reflect periods of regional climate deterioration that are observed in the Rhone watershed.

lmpact of bottom trawling on benthic ecology along the coastal waters of Kerala with special reference to meiofauna

School of Industrial Fisheries, Cochin University of Science and Technology

Abiotic parameters and abundances, dominance and diversity of benthic macro- and meiofauna in Kongsfjord, Spitsbergen

The intertidal and subtidal soft bottom macro- and meiofauna of a glacier fjord on Spitsbergen was studied after complete ice melt in June 2003. The abundances of the benthic fauna were within the range reported from estuaries and similar intertidal areas of boreal regions. The high proportion of juveniles in the eulittoral zone indicated larval recruitment from subtidal areas. The macrobenthic fauna can be divided into an intertidal and a subtidal community, both being numerically dominated by annelids. Deposit feeders were numerically predominant in intertidal sites, whereas suspension feeders were most abundant in the subtidal area. Among the meiofauna, only the benthic copepods were identified to species, revealing ecological adaptations typical for intertidal species elsewhere.