Historical Data Reveal 30-Year Persistence of Benthic Fauna Associations in Heaviy Modified Waterbody

Baseline surveys form the cornerstone of coastal impact studies where altered conditions, for example through new infrastructure development, are assessed against a temporal reference state. They are snapshots taken before construction. Due to scarcity of relevant data prior to baseline surveys long-term trends can often not be taken into account. Particularly in heavily modified waterbodies this would however be desirable to control for changes in anthropogenic use over time as well as natural ecological variation. Here, the benthic environment of an industrialized embayment was investigated (Swansea Bay, Wales, UK) where it is proposed to build a tidal lagoon that would generate marine renewable energy from the tidal range. Since robust long-term baseline data was not available, the value of unpublished historical benthos information from 1984 by a regional water company was assessed with the aim to improve certainty about the persistence of current benthic community patterns. A survey of 101 positions in 2014 identified spatially discrete benthic communities with areas of high and low diversity. Habitat characteristics including sediment properties and the proximity to a sewage outfall explained 17–35% of the variation in the community structure. Comparing the historical information from 1984 with 2014 revealed striking similarity in the benthic communities between those years, not just in their spatial distribution but also to a large extent in the species composition. The 30-year-old information confirmed spatial boundaries of discrete species associations and pinpointed a similar diversity hotspot. A group of five common species was found to be particularly persistent over time (Nucula nitidosa, Spisula elliptica, Spiophanes bombyx, Nephtys hombergii, Diastylis rathkei). According to the Infauna Quality Index (IQI) linked to the EU Water Framework Directive (WFD) the average ecological status for 2014 was “moderate,” but 11 samples showing “poor” and “bad” status indicated possible negative impacts of dredge spoil disposal. Generally the study demonstrated the value of historical information for assessing the persistence of benthic community characteristics, while also highlighting shortcomings if raw data is lost and if the historical baseline does not reflect pristine ecological conditions

Marine bioinvasion: concern for ecology and shipping

Marine bioinvasion - introduction of marine organisms alien to local ecosystem through ship hulls and ballast water - has serious consequences to native biota, fishery and general coastal ecosystem. Over 80% of the world cargo is mobilized transoceanically and over 12 billion tones of ballast water is filled at one part of the ocean and discharged at the other. These ballast waters offer conducive situation for bacteria, viruses, algae, dinoflagellates and a variety of macro-faunal larval/cyst stages to translocate to alien regions, usually along the coasts of the continents. As an example, there are over 18 species of animals and plants documented along the Indian coasts as those that might have got invaded and established. They can cause deleterious effects to local flora and fauna through their toxigenic, proliferative and over-competitive characteristics. This article points out the threats arising out of marine bioinvasion and various technological developments needed to deal with this unavoidable scourge in global shipping transport

Studies on Sublittoral Macrobenthic Fauna of the Inner Swansea Bay

75-78Sublittoral benthic macrofauna ofInner Swansea Bay, a shallow industrialized embayment on the north side ofthe Bristol Channel, England, is mainly composed of Polychaeta (43.9%), Mollusca (31.9%), Crustacea (12.7%), Echinodermata (0.7%) and other groups (10.6%). Faunal density and biomass varied from 50 to 3174 specimens m-2 (x = 787 m -2) and 0.5 to 2190.0 gm-2 (x = 116.65 gm-2) respectively. High benthic biomass was dominated by the bivalves Spisula elliplica (Brown) and Nucula turgida Leckenby and Marshall. The annual benthic production of 233.3 gm-2 yr-1 or 16.2 g Cm-2 yr-1 can sustain 22.3 tons km-2 yr--1 of bottom fishes, and carbon requirement by the benthic community is 16.2.g C m-2 yr-1. There was a definite correfation among the benthic faunal element, their feeding habit, organic carbon and sediment texture

Interdependence of environmental parameters and sand dwelling benthic species abundance : A multivariate approach

232-234Multivariate analysis showed dependence of distribution and abundance of sand dwelling fauna on more than one ecologically significant environmental parameters rather than one ecological master factor. Salinity, grain size, beach gradient, dissolved oxygen and availability food together formed significant factors to explain 76% of the total variables. Canonical variate analysis further revealed interdependence of abiotic and biotic factors showing high value of correlation coefficient (P < 0.001). It is postulated that one can predict the occurrence of species and their abundance at a tropical beach under given condition and time at given place, provided there is no disturbance factor(s)-pollution and/or human interference

Environmental influences on the species diversity, biomass and population density of soft bottom macrofauna in the estuarine system of Goa, west coast of India

187-193A total of 58 species were recorded belonging to polychaetes, molluscs, crustaceans and other minor groups in order of species abundance. eighteen species are new to the local fauna that were not reported earlier. The maximum mean species diversity index (Shannon-Wiener), total biomass (wet) and total population density recorded were 2.3 (Z1), 6.7 g/m² (M1) and 703 no./m² (M2) respectively. Significantly higher species diversity was observed at high salinity, fine sand and high sedimentary biochemical parameters of total organic carbon (TOC), total organic nitrogen (TON) and carbon of biopolymeric fraction (C-BPF) sites. Medium grain size sites supported significant high biomass whereas population density showed no significant difference among the sites. The best multiple linear regression model revealed that all the 13 parameters studied were significant influencing parameters on species diversity, biomass and population density with exception of temperature. Among these salinity and TON were the main significant parameters. The combination of significant influencing environmental parameters, % variation and Mallows' Cp values varied from sites to biotic parameters. This explained 32-72% of the total variance. The regression model derived from this data helps in detection of these biotic parameters and detection of pollution-induced effects

Soft sediment dwelling macro-invertebrates of Rajapur bay, central west coast of India

31-34Thirtyfour species of soft sediment dwelling macro-invertebrates were recorded in Rajapur bay at the proposed effluent discharge location of nuclear power plant. The fauna mainly composed of polychaetes (42.52%), molluscs (39.03%), crustaceans (7.86%), sipunculids (1.23%), echiurids (7.86%) and cephalochordates (1.5%). Deposit feeder spionidae-Prionospio pinnata and filter feeder bivalve-Pecten sp. formed the dominant and co-dominant species respectively. Maximum population density and wet biomass recorded were 2,675 m - 2 (XBAR = 445 +/- 507) and 26.5 g m-2 (XBAR = 6.01 +/- 6.2 1) respectively. Annual benthic production was estimated to be 12.02 g.m-2.y-1. Species diversity varied from 0.91 to 3.61 (XBAR = 2.2 +/- 0.75). High species diversity value showed the stability of the environment. Dominance diversity curve showed eveness of benthic fauna. This was reflected on the competition equilibrium period of the population. Species similarity cluster of different stations were formed largely due to habitat specific and feeding behaviour of the species. The spatio-temporal variations and community structure fluctuations of macro-invertebrates are mainly due to the effect of southwest monsoon and the impact of localized biotic and abiotic factors. Benthic fauna in this bay is in natural ecological balance and free from an apparent effect of environmental imbalances. The base line data generated here can be used to assess the impact of pollution, if any, in future

Benthos off Cochin, southwest coast of India

57-59Macro-invertebrate benthic fauna off Cochin mainly composed of polychaeta (82.45%), crustacea (7.62%), mollusca (5.92%), sipuncula (2.25%), nemertinea (0.96%) and echinodermata (0.80%). The maximum population density and biomass values were 304 ± 25 m-2 and 2.37 ± 0.32 g.m.-2 respectively. The fauna were relatively rich in medium size particles than the finer particles. The population density and biomass decreased with increase in depth. It seems that depth, sediment characteristics, dissolved oxygen and availability of food are important factors in the distribution and abundance of sediment dwelling macro-fauna in the sub-littoral region off Cochin

Population distribution of meiofauna in relation to some environmental features in a sandy intertidal region of Goa, west coast of India

259-264Meiofauna population of Candolim beach mainly composed of nematoda (40.15%), harpacticoida (30.75%), turbellaria (23.35 %) and other groups which included polychaeta, bivalvia and mystacocardia. The maximum total meiofauna population encountered was 3525.10 cm-2. Temporal variation of meiofauna showed increase of meiofauna population from post to premonsoon season and it was maximum in April. The fauna was very poor in southwest monsoon season. Spatial distribution of meiofauna showed maximum densities at 10 m station. Two way ANOVA among the spatio-temporal variation showed significant variation between the seasons. Vertical distribution of meiofauna showed (i) aggregation of meiofauna population at lower depth. (ii) nematoda throughout the core depth and (iii) other taxa at lower depth. Among the environmental parameters studied grain size, porosity, slope of beach, salinity and availability of food were important factors in the distribution and abundance of meiofauna taxa in the intertidal region of Candolim beach

Bioturbation by <i>praxillella pacifica</i> (Polchaeta:Maldanidae) and its effect on <i>Chone</i> sp.(Polycheta:Sabellidae) in tomioka Bay, Amakusa,Japan

276-279Quantitative estimation of bioturbation by burrrowing deposit feeding species P.pacifica is carried out in laboratory.he mean value of sediment reworking rate varies from 164.5 to 636.51 mg wet animal‑1.d-1. The sediment turn over is dependant on body width and time variable. Bioturbation is largely controlled by population density, ambient temperature and sediment characterstics. Annual turnover of sediments is estimated to be 84.3 kg. Wet m-2 . This lagrge amount of sediments turnover has potential importance in the transfer of nutrients from the sediments to the wter column. Protien values of sediments, grain size ,water content and feeding habit of dominant species are related to sediment turnover. Adult-adult interaction experiment between P.pacifica and filter feeder Chone sp. shows co-existence of these species, largely due to diversified feeding habit and habitat