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The epibenthic euryhaline hydromedusa Vallentinia gabriellae Vannucci Mendes, 1948 is an olindiid species native to tropical Atlantic waters. Here, we describe the cryptic introduction of this species in an estuary along the coast of Kerala, in southwestern India. This study records the existence of V. gabriellae outside of Atlantic waters for the first time and documents its geographical range expansion. Our identification was based on a combined morphological and DNA barcoding assessment using the COI and 28S markers. Although we noted some morphological differences between our specimens and those from their native range, our findings were conclusive. We suggest that phenotypic plasticity may result from differences such as prey availability between the native and introduced habitats. V. gabriellae medusae are epibenthic and cling to a variety of hard and soft substrates, including bivalves. Our specimens were associated with the invasive fouling mussel Mytella strigata , and we suggest that V. gabriellae could have been transported along with these mussels to the Kerala coast. [ABSTRACT FROM AUTHOR]

The proportion of blue carbon contribution by benthic fauna with regard to climate change issue is a relevant topic recent times. The present study is focusing on the carbon potential and blue carbon contribution of meiobenthic nematodes in the intermediate zone of Arctic Kongsfjord during 2015–2017 and the study is the first of its kind from this region. Foraminifera and Nematoda were the dominant fauna in 2015; whereas it was Foraminifera in 2016 and Tintinnida and Nematoda in 2017. Significant difference was noticed in the community structure of meiofauna in this three consecutive years. Twenty six nematodes were identified from the intermediate zone and their individual carbon potential and total blue carbon during the above-mentioned period is estimated. Parasphaerolaimus paradoxus (7.14 ± 0.05 μg/mg) recorded the highest carbon potential and the lowest value was recorded in Terschellingia longicaudata (0.11 ± 0.3 μg/mg). The sediment factors such as sediment granulometric composition, salinity, pH, Eh and total organic carbon (TOC) were the leading factors influencing the meiofaunal distribution as well as the distribution of nematodes based on carbon potential in the intermediate zone. Investigation of blue carbon deposition by nematodes turned out to be relevant in mitigating the climatic change as the fjord has a tranquil nature. [ABSTRACT FROM AUTHOR]

Mangroves support and enhance fisheries by serving as a breeding ground and nursery habitat for aquatic life. While mangroves are widely recognized for their role in enhancing both small scale and commercial fisheries, they are rapidly disappearing. The understanding of this ecosystem service and its value in both social and economic terms will help enhance the sustainable management of both mangroves and fisheries. This paper provides a critical review of mangroves and their importance in capture fisheries and also discusses the ecological significance of this ecosystem in fisheries enhancement by explaining the different mangrove associated fisheries. As the fisheries value of mangroves is highly site-specific, the paper illustrates the drivers and values of mangrove associated fisheries. Decision-makers can use this information to make decisions relating to conservation and restoration of mangrove ecosystems and sustainable fishing. [ABSTRACT FROM AUTHOR]

Benthic biotic indices are important ecological tools extensively used to understand the ecological quality of coastal wetlands. The present study aimed to assess the ecological status of Kodungallur-Azhikode estuary for the first time by using widely used benthic indices such as species richness (S), Shannon diversity index (H′log2), BENTIX, benthic opportunistic polychaetes amphipods (BOPA), AZTI's Marine Biotic Index (AMBI) and multivariate AMBI (M-AMBI). In the canonical correspondence analysis, salinity, dissolved oxygen, organic matter, sediment Eh, sediment pH and sand were identified as important variance descriptors. A single species of an opportunist, Americorophium triaeonyx, an amphipod belonging to the ecological group (EG) III, significantly contributed to the total macrofaunal density. Other dominant opportunistic species included Obelia bidentata (EGII), Arcuatula senhousia (EGIII), Cirolana fluviatilis (EGII), Prionospio cirrifera (EGIV) and Capitella sp. (EGV). The overall assessment indicated a 'good to moderate' condition in AMBI, 'good to poor' condition in M-AMBI, 'high to moderate' condition in BENTIX, 'high to poor' condition in BOPA and 'moderate to poor' condition in univariate Shannon diversity index. All the multivariate indices tested in the study were correlated with each other except BOPA and M-AMBI. The group of stations dominated with a sandy substrate and a moderate level of organic content indicated high to good conditions while other stations demonstrated moderate to poor conditions. However, no significant variation in indices tested between seasons was observed. The present study recommends long-term monitoring of benthic macroinvertebrate assemblages with proper taxonomic identification and functional trait analysis for better calibration of indices, which is the key factor for getting better results. [ABSTRACT FROM AUTHOR]

Phytoplankton community structure along the coastal waters of the Northeastern Arabian Sea (NEAS) was analysed for three years (2009, 2011 and 2012) during the winter monsoon season. The coastal waters of NEAS, especially Saurashtra coast are a region of high fishery potential. A total of 137 species of phytoplankton were identified. The community structure of phytoplankton showed significant inter-annual variability. The study highlights the persistence of certain non-indigenous phytoplankton species such as Scrippsiella trochoidea, Karenia mikimotoi and potentially harmful dinoflagellates mainly Gonyaulax polygramma, Dinophysis acuminata, D. miles and Tripos furca in the region that can raise probable threats towards the indigenous species and can cause harmful or toxic events. The increased abundance of diatom, Pseudo-nitzschia spp. that can produce toxins at certain threshold levels was also observed. The possible reason for the increased abundance of such groups can be suggestively due to the increased anthropogenic inputs into the coastal waters and intense fishing and maritime activity in the area. [ABSTRACT FROM AUTHOR]

Morphological identification of the marine cyclopoid copepodDioithona rigidain combination with sequencing a 645 bp fragment of mitochondrial cytochrome oxidase c subunit I (mtCOI) gene, collected from offshore waters of Kavarathi Island, Lakshadweep Sea, is presented in this study. Kiefer in 1935 classifiedDioithonaas a separate genus fromOithona. The main distinguishing characters observed in the collected samples, such as the presence of well-developed P5 with 2 setae, 5 segmented urosome, 12 segmented antennule, compact dagger-like setae on the inner margin of proximal segment of exopod ramus in P1–P4 and engorged portion of P1-bearing a spine, confirmed their morphology toD. rigida.A comparison of setal formulae of the exopod and endopod ofD. rigidawith those recorded previously by various authors are also presented here. Maximum likelihood Tree analysis exhibited the clustering ofD. rigidasequences into a single clade (accession numbers KP972540.1-KR528588.1), which in contrast was 37–42% divergent from otherOithonaspecies. Further intra-specific divergence values of 0–2% also confirmed the genetic identity ofD. rigidaspecies.Paracyclopina nanawas selected as an out group displayed a diverged array. The present results distinctly differentiatedD. rigidafrom otherOithonaspecies. [ABSTRACT FROM PUBLISHER]

The cumulative effects of global change, including climate change, increased population density and domestic waste disposal, effluent discharges from industrial processes, agriculture and aquaculture will likely continue and increases the process of eutrophication in estuarine environments. Eutrophication is one of the leading causes of degraded water quality, water column hypoxia/anoxia, harmful algal bloom (HAB) and loss of habitat and species diversity in the estuarine environment. The present study attempts to characterize the trophic condition of coastal estuary using a simple tool; trophic index (TRIX) based on a linear combination of the log of four state variables with supplementary index Efficiency Coefficient (Eff. Coeff.) as a discriminating tool. Numerically, the index TRIX is scaled from 0 to10, covering a wide range of trophic conditions from oligotrophic to eutrophic. Study area Kodungallur-Azhikode Estuary (KAE) was comparatively shallow in nature with average depth of 3.6 ± 0.2 m. Dissolve oxygen regime in the water column was ranged from 4.7 ± 1.3 mgL in Station I to 5.9 ± 1.4 mgL in Station IV. The average nitrate-nitrogen (NO-N) of KAE water was 470 mg m; values ranged from Av. 364.4 mg m at Station II to Av. 626.6 mg mat Station VII. The mean ammonium-nitrogen (NH-N) varied from 54.1 mg m at Station VII to 101 mg m at Station III. The average Chl- a for the seven stations of KAE was 6.42 ± 3.91 mg m. Comparisons over different spatial and temporal scales in the KAE and study observed that, estuary experiencing high productivity by the influence of high degree of eutrophication; an annual average of 6.91 TRIX was noticed in the KAE and seasonal highest was observed during pre monsoon period (7.15) and lowest during post monsoon period (6.51). In the spatial scale station V showed high value 7.37 and comparatively low values in the station VI (6.93) and station VII (6.96) and which indicates eutrophication was predominant in land cover area with comparatively high water residence time. Eff. Coeff. values in the KAE ranges from −2.74 during monsoon period to the lowest of −1.98 in pre monsoon period. Present study revealed that trophic state of the estuary under severe stress and the restriction of autochthonous and allochthonous nutrient loading should be keystone in mitigate from eutrophication process. [ABSTRACT FROM AUTHOR]

Heavy metal contamination has threatened India's biodiverse-rich coastal wetlands, backwaters, rivers, estuaries and mangroves due to unscientific industrial activities and urbanisation. Among the Indian states, the Cochin city is the commercial and economic hub of Kerala along the coastal belt of Arabian Sea. Mangroves located are on the backwater channels and along the banks of Cochin estuary are near victims of this commercialization. Therefore, a comprehensive analysis of the sediment quality focusing on heavy metal contamination and pollution problems are documented from the mangrove habitats of Cochin, considering their immense ecological services offered to the coastal communities with an insight for future restoration activities. Out of the 17 metals analysed, concentration of 6, largely exceeded NOAA effect range low (Cr (5.5–202), Cu (0.89–40.68), Cd (0–1.34), Hg (0–0.68)) and effect range medium (Ag (0–4.68), Ni (0.06–64.5)), which marks the probability of adverse biological effects on mangrove plants and animals. Enrichment factor analysis revealed extremely severe enrichment of Ag (EF = 133), Hg (18.8), Pb (17.8) and Cd (17) and was supported by PCA analysis, that clearly derived the anthropogenic influence of Ag, Cd and Hg in mangroves. Contamination factor, geoaccumulation index and pollution load index revealed that the mangrove sites of Cochin are nearly stressed due to contamination (CF = 66.8) and extreme pollution effects (Igeo = − 1.8–5.4) due to silver, and considerably contaminated (CF = 4.4) with Cd especially in Aroor and Vypin zones. However, Valanthakad zone was almost free from metal pollution having better sediment quality where mangrove vegetation had luxuriant growth. [ABSTRACT FROM AUTHOR]