A group of small bivalves inhabiting Indian brackish-water estuaries and lagoons (known locally as backwaters), variously assigned to
,
, and
, are reviewed and, based on shell characters, shown to ...be congeneric. Molecular (COI) and morphological data indicate that this group belongs to the family Myidae. Furthermore, the combined data suggest that these Indian myids are a sister taxon of the genus
. The Indian material studied herein exhibits a functional morphology typical of infaunal bivalves, whereas typical
are nestling and epibyssate. A new genus,
, is thus erected for the Indian group and includes five species, one of which is named in this study.
Oliver, Hallan & Jayachandran,
is described from the Cochin Backwater on the western coast of India.
(Preston, 1916) is transferred to
. Additionally, the west coast taxa
(Preston, 1907),
(Preston, 1911) and
(EA Smith, 1893) are recognised herein.
Preston, 1907,
Preston, 1907,
Preston, 1907 and
Preston, 1907 are placed in synonymy with
, and
Preston, 1915 is synonymised with
.
Abstract Specimens of the harpacticoid copepod Eudactylopus fasciatus Sewell, 1940 were found in plankton samples taken from Lakshadweep, India. In this study, E. fasciatus is redescribed on several ...additional distinct morphological characters along with the original description dating back to 1940 (Sewell, 1940). The most important features of E. fasciatus from Bangaram Island are the external coloration pattern with eight longitudinal bands, additional numbers of setae on the 1st, 2nd, 3rd, and 7th segments of the A1, and the modified saber-shaped sexually dimorphic second endopod segment of the male P2 with a bud-like structure. The illustrated redescription and a taxonomic key for the identification of all the species of the genus Eudactylopus are also provided.
The effects of sub-lethal concentrations of lindane on behavioral, hematological and histological parameters in Etroplus maculatus were investigated. The LC50 value of lindane for E. maculatus was ...estimated using the Probit method and was found to be 0.028 mg/L. The red blood cell count (RBC) and the hemoglobin (Hb), hematocrit (Ht), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were significantly reduced (p > 0.0001) in fish exposed to the toxicant concentrations compared to the control groups. However, the white blood cell count (WBC) was observed to be significantly higher (p < 0.0001). Observations of the tissues showed that lindane had profound destructive effects on the gills, liver and kidney of the fish. The gills showed proliferation of the lamellar epithelium and lamellar fusion, the liver showed necrosis and the kidneys had constriction of the tubular lumen. The frequency of observed behaviors had the same levels of significance throughout the period of study. There was a reduction in the frequency of occurrence between test concentrations, but remained significantly higher than the control. The study shows that lindane is harmful to E. maculatus at sub-lethal concentrations and that the application of this pesticide close to bodies of water is a dangerous threat to aquatic life.
► Effects of sub-lethal concentrations of lindane on behavioral, hematological and histological parameters in Etroplus maculatus were investigated. ► The blood parameters (RBC, Hb, Ht, MCH, MCV, MCHC) were significantly reduced in fish exposed to toxicant concentrations. ► Gills showed proliferation of the lamellar epithelium and lamellar fusion, the liver showed necrosis and the kidneys had constriction of the tubular lumen. ► Application of the pesticide, lindane close to bodies of water is a dangerous threat to aquatic life.
The accumulation trends of Cu, Zn, Pb and Ni and their effects on two native species,
Etroplus suratensis
and
Villorita cyprinoides
from Cochin estuary and their biomarker responses were explored. ...Bioaccumulation and metal selectivity index (MSI) in
E. suratensis
for gill and liver showed the highest accumulation for Zn (209.33 ± 17.14 mg kg
−1
) followed by Cu (64.16 ± 8.07 mg kg
−1
), while in
V. cyprinoides
Cu showed the highest accumulation (80.78 ± 6.92 mg kg
−1
) in gill tissue followed by Zn (65.28 ± 7.06 mg kg
−1
). Histological alterations were evaluated in gill and liver tissues of
E. suratensis
using histopathological index (
I
h
) method. Lamellar hyperplasia and deformed lamellar architecture were the evident changes in gill tissue, while the alterations in liver tissues were marked by the presence of melanomacrophage centers and necrotic lesions in liver parenchyma. The high target hazard quotient (THQ) obtained for Pb (0.94) indicated that the daily consumption of aquatic products contaminated with metals Pb, Cu and Zn has obvious health risk to human consumption. Thus, the elevated metal accumulation rate in the tissues with supportive histological changes suggests that these alterations can serve as definite signature of heavy metal contamination in native organisms of Cochin estuary.
Research highlights
The tissue-specific bioaccumulation and metal selectivity index (MSI) of E. suratensis and V. cyprinoides revealed significantly higher accumulation of Cu and Zn compared to Pb and Ni throughout the study with higher rates during non-monsoonal periods.
The histopathological studies in fish, E. suratensis from field conditions portrayed significant histopathological alterations such as hyperplasia, deformed secondary lamellae in gill tissues; melanomacrophage centres and necrotic lesions in liver.
The estimation of human health risk assessment of heavy metals (Cu, Zn and Pb) of E. suratensis from Cochin estuary denoted a possible risk from consumption of fishes from the Cochin estuary.
Drought is a hydrological disturbance, predicted to aggravate in a climate change scenario. It causes habitat loss and fragmentation for aquatic organisms, including benthic fauna. The hydrological ...disturbance is an environmental filter, retaining only taxa possessing suitable traits for survival. Here a trait-based perspective was used to study the benthic macroinvertebrate assemblage in a seasonal wetland subjected to hydrological disturbance. Maranchery Kole wetland (a part of the Ramsar site Vembanad Kole wetland), was unusually transformed into a terrestrial landscape with discrete aquatic patches. Benthic macroinvertebrates were collected from aquatic patches. 55 categories of 10 biological traits, which could be assigned across the benthic genus were defined from literature. To delineate the faunal groups with similar trait assembly, the taxa by trait data matrix was subjected to Gower's distance‐based hierarchical agglomerative cluster analysis. Benthic macroinvertebrates belonged to 23 genera from 8 families, 4 orders, 2 classes, and 2 phyla. Their predominant traits were small body size, short life cycle duration, multivoltine life cycle, aquatic larval stage, aerial active dispersal, cocoons as resistant form, locomotion by crawling, tegumental respiration, asexual reproduction, and deposit-feeding. Traits-based classification of taxa resulted in 4 clusters. In each cluster, unique trait combinations ensured the survival of taxa. Group a persisted through desiccation resistant forms and proliferated through asexual reproduction using resource dominance strategy. Groups b and c, without desiccation resistant forms, used active aerial dispersal to colonize the aquatic patches. Group d was tolerant to unfavorable environments including morphological adaptations. Since the active dispersal trait facilitated active habitat selection in groups b and c, their presence was occasional. Groups a and d were incapable of active habitat selection due to passive dispersal traits, ensuing in their persistence throughout the study period.
The phytoplankton standing crop was assessed in detail along the South Eastern Arabian Sea (SEAS) during the different phases of coastal upwelling in 2009. During phase 1 intense upwelling was ...observed along the southern transects (8 degree N and 8.5 degree N). The maximum chlorophyll a concentration (22.7 mg/m super(3)) was observed in the coastal waters off Thiruvananthapuram (8.5 degree N). Further north there was no signature of upwelling, with extensive Trichodesmium erythraeum blooms. Diatoms dominated in these upwelling regions with the centric diatom Chaetoceros curvisetus being the dominant species along the 8 degree N transect. Along the 8.5 degree N transect pennate diatoms like Nitzschia seriata and Pseudo-nitzschia sp. dominated. During phase 2, upwelling of varying intensity was observed throughout the study area with maximum chlorophyll a concentrations along the 9 degree N transect (25 mg/m super(3)) with Chaetoceros curvisetus as the dominant phytoplankton. Along the 8.5 degree N transect pennate diatoms during phase 1 were replaced by centric diatoms like Chaetoceros sp. The presence of solitary pennate diatoms Amphora sp. and Navicula sp. were significant in the waters off Kochi. Upwelling was waning during phase 3 and was confined to the coastal waters of the southern transects with the highest chlorophyll a concentration of 11.2 mg/m super(3). Along with diatoms, dinoflagellate cell densities increased in phases 2 and 3. In the northern transects (9 degree N and 10 degree N) the proportion of dinoflagellates was comparatively higher and was represented mainly by Protoperidinium spp., Ceratium spp. and Dinophysis spp.
Mangrove forests are considered as some of the world’s most productive ecosystems. However, these unique ecosystems are under pressure due to natural as well as anthropogenic threats globally. Kerala ...state, situated on the west coast of India, has lost 95% of the mangroves during the last three decades. The floristic diversity of mangroves in Kerala was represented by 18 species of true mangroves of which, Sonneratia alba, Avicennia alba, and Ceriops tagal were found to be rare in the State. This review examines the current status of mangrove vegetation along the Kerala coast, factors responsible for the decline of mangroves, various conservation measures adopted and the future prospects. It was found that scientific information on the mangrove area of many districts in this southern state of India is still lacking. In this context, GIS and remote sensing would be an effective tool for the identification and mapping of various mangrove patches in Kerala. Furthermore, the conservation and restoration programs of mangroves in the state have been accelerated after the 2004 Indian Ocean earthquake and tsunamis. Since mangroves are separate and unique ecosystems in the marine environment, exclusive mangrove forest conservation laws need to be framed, legislated and enforced. Along with this, site-specific and community-based mangrove rejuvenation and restoration programs have to be employed for the long-term management and conservation of this fast dwindling ecosystem.
An examination of a syntype of
Cuspidaria cochinensis
Preston, 1916, focusing on the characters of the hinge, supports the transfer of this species to the family Corbulidae. Recently collected ...material from the Cochin Backwater is used to describe the shell and anatomy of the adult form. The ctenidia are composed of two demibranchs, both flat and homorhabdic, this further confirming that this species is eulamellibranch and not septibranch. The most appropriate generic placing of this species is in
Cuneocorbula
; thus, it is the first recorded extant species of the genus.
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.
Community structure and distribution of chaetognaths were investigated along the upwelled and non-upwelled waters of Southeastern Arabian Sea (SEAS) from the coastal, shelf and open ocean regions. ...With the onset of monsoon, intense upwelling along the southern part of SEAS (8° 28′ N) and a weak coastal upwelling along the northern counterpart (15° 30′ N) was evident. Zooplankton biomass was observed to be high in the upwelled waters with the dominance of copepods. Chaetognaths were also observed in significant numbers all along the SEAS, however maximum numerical abundance was observed in the southern upwelled waters. Chaetognaths belonging to 10 genera were identified of which genus
Flaccisagitta
(54%) made the most dominant group along the entire study area followed, in order of abundance, by
Serratosagitta
(20%),
Mesosagitta
(18.2%),
Sagitta
(12.3%),
Ferosagitta
(11%) and
Krohnitta
(6.4%).
Flaccisagitta
were observed to be abundant in the upwelled waters along with
Pterosagitta, Serratosagitta, Sagitta, Krohnitta
and
Ferosagitta
whereas genus
Mesosagitta
dominated the non-upwelled waters of northern transects.
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