Repeatability of energy metabolism and resistance to dehydration in the invasive slug Limax maximus

Standard metabolic rate (SMR) and resistance to body dehydration (BD) are important physiological traits that have an effect on water balance and the amount of energy available for activity and production, and thus could contribute to variation in life history traits expressed across a range of environments. Few studies have tested whether SMR and BD show consistent between‐individual variation in molluscs. Significant repeatability of SMR and BD indicates that the traits might be heritable and therefore a possible target for natural selection, so describing the repeatability of SMR and BD is important in studies of phenotypic variability. Here, we studied energy metabolism (body mass‐corrected SMR) and the change in the scaling relationship of SMR and body mass in response to time between measurements in the giant garden slug Limax maximus. Limax maximus is one of the most invasive terrestrial molluscs, with a wide geographical distribution, and is considered an important pest of horticultural and agricultural crops. Our results show that L. maximus follows the expected relationship of increasing SMR with increasing mass, but the scaling exponent varies through time and is different from that described for other gastropods. We also found significant inter‐individual variation in VCO_{2 Mean}, VCO_{2 Min}, VCO_{2 Max}, and BD (τ=0.25, 0.29, 0.24, 0.22, p<0.05, respectively), and significant repeatability of body mass (τ=0.90). To our knowledge, this is the first comprehensive analysis of the repeatability of body mass‐corrected SMR and BD in terrestrial slugs. Our results suggest that energy metabolism and water balance could potentially respond to selection.     

Standard metabolic rate models for Carmine Shiner (Notropis percobromus) and Common Shiner (Luxilus cornutus) across different temperature regimes

Standard metabolic rates (SMR) were measured empirically for carmine shiner Notropis percobromus and common shiner Luxilus cornutus to develop SMR models that predict metabolic responses of each species under thermal conditions observed in the wild. SMR increased significantly with body mass and rising water temperature, ranging from 0.05 mg O₂ h⁻¹ at 10°C to 0.89 mg O₂ h⁻¹ at 20°C for N. percobromus weighing 0.6–2.5 g and from 0.11 mg O₂ h⁻¹ at 10°C to 0.98 mg O₂ h⁻¹ at 20°C for L. cornutus weighing 0.8–6.6 g. SMR models significantly differed between sympatric species on account of differences in model intercepts (RA) and temperature coefficients (RQ), however, the allometric relationships between mass and SMR did not significantly differ between species. Known distribution of N. percobromus and L. cornutus includes the Birch River located in Manitoba, Canada, where N. percobromus is listed as Endangered. Little is known about the physiology of N. percobromus or the species' ability to acclimate or adapt to different environmental conditions. While size differences between species contributed, in part, to differences in SMR predictions for Birch River populations, SMR trends (< 2 mg O₂ h⁻¹) for individuals weighing 1 g were similar for both species across daily temperatures. Respirometry experiments contributed to developing species-specific SMR models and inform on the effect of natural and anthropogenic stressors, namely water temperature, on the conservation of N. percobromus in this ecosystem.     

Nectar‐providing plants enhance the energetic state of herbivores as well as their parasitoids under field conditions

Abstract 1. The use of flowering vegetation has been widely advocated as a strategy for providing parasitoids and predators with nectar and pollen. However, their herbivorous hosts and prey may exploit floral food sources as well. 2. Previous laboratory studies have shown that not all flower species are equally suitable in providing accessible nectar. Relatively little is known about actual nectar exploitation under field conditions. 3. The present study investigates nectar exploitation by the pest, Plutella xylostella, and its parasitoid, Diadegma semiclausum, under field conditions and examines whether floral nectar exploitation in the field can be predicted based on controlled laboratory studies. 4. Insects were collected from fields bordered by flowering margins containing Fagopyrum esculentum, Lobularia maritima, Anethum graveolens, Centaurea jacea or the grass Lolium perenne (control). Whole insect bodies were individually assayed by HPLC to establish their sugar profile as a measure of the level of energy reserves and the degree of food source use. 5. The average overall sugar content of P. xylostella and D. semiclausum collected in fields bordered by flowering margins was significantly higher than those of individuals collected from grass‐bordered control plots. To the authors’ knowledge, this represents the first demonstration that nectar‐providing plants enhance the energetic state of herbivores under field conditions. 6. In contrast to earlier laboratory studies, the present study did not find elevated sugar contents in P. xylostella and D. semiclausum individuals collected from fields bordered by buckwheat (F. esculentum). 7. The present study shows widespread sugar feeding by both the herbivore and its parasitoid. It also shows that laboratory studies establishing nectar exploitation under controlled conditions can not always be extrapolated to actual exploitation under field conditions. This emphasises the importance of studying field‐collected insects with regard to food source use and nutritional status.     

Control of invasive marine invertebrates: an experimental evaluation of the use of low salinity for managing pest corals (Tubastraea spp.)

This study investigated the use of low salinity as a killing agent for the invasive pest corals Tubastraea coccinea and Tubastraea tagusensis (Dendrophylliidae). Experiments investigated the efficacy of different salinities, the effect of colony size on susceptibility and the influence of length of exposure. Experimental treatments of colonies were carried out in aquaria. Colonies were then fixed onto experimental plates and monitored in the field periodically over a period of four weeks. The killing effectiveness of low salinity depended on the test salinity and the target species, but was independent of colony size. Low salinity was fast acting and prejudicial to survival: discoloration, necrosis, fragmenting and sloughing, exposure of the skeleton and cover by biofoulers occurred post treatment. For T. tagusensis, 50% mortality (LC₅₀) after three days occurred at eight practical salinity units (PSU); for T. coccinea the LC₅₀ was 2?PSU. Exposure to freshwater for 45–120?min resulted in 100% mortality for T. tagusensis, but only the 120?min period was 100% effective in killing T. coccinea. Freshwater is now routinely used for the post-border management of Tubastraea spp. This study also provides insights as to how freshwater may be used as a routine biosecurity management tool when applied pre-border to shipping vectors potentially transporting non-indigenous marine biofouling species.     

Floral resources foraged by Geotrigona argentina (Apidae,Meliponini) in the Argentine Dry Chaco forest

This study is the first contribution to knowledge of the relationships between Geotrigona argentina and the plants of the Argentine Dry Chaco forest. A total of 1260 g of honey (corresponding to 146 pots) and 763 g of pollen (63 pots) stored in four underground nests was studied. The honey pots from each nest were homogenised and the four honey samples were analysed by melissopalynological methods, whereas the pollen pots were studied individually. Both classical counts and counts affected by the volume of the pollen types were carried out. Pollen data were statistically analysed. Additional data on both protein and lipid content is also provided. A total of 39 pollen taxa were identified. Pollen collection was focused on a few pollen taxa: Prosopis, Castela coccinea, Maytenus and Capparis; these taxa, together with Ziziphus mistol and Pisonia zapallo, were also important nectar sources. The preliminary results show that pollen collection varied seasonally, being most diverse in the summer when G. argentina incorporates herbaceous plants into its diet. The pollen collection spectrum of G. argentina is similar to that of other Trigonina bees in that the main plant species collected are a few large shrubs or trees, whose flowering consists of small and clustered flowers. Pots with large amounts of monofloral loads with pollen from only a few species suggests an organised foraging behaviour that includes the recruitment of foragers, such as that observed in other eusocial bees.     

The cost of living slowly: metabolism,Q10 and repeatability in a South American harvestman

Abstract Resources are usually considered to be limited in caves and underground habitats. Therefore, lower metabolic rates of ectotherms in these environments should be advantageous. The standard metabolic rate (SMR) of the common harvestman Pachylus paessleri Roewer, 1913 (Arachnida, Opiliones) is determined at two ambient temperatures. Repeatability of SMR is estimated by two methods: (i) product–moment correlation on residuals of body mass and (ii) variance components. Estimations of the thermal sensitivity of metabolic rate (individual Q₁₀). SMR of P. paessleri at 20 °C show a mean of 19.01 ± 6.04 and 14.99 ± 3.64 μL CO₂ h^?1 for males and females, respectively. Thermal sensitivity of SMR is 2.11 ± 0.23 with a substantial coefficient of variation of 26.7%. In males, residuals of CO₂ release are significantly repeatable (r_p = 0.61) between measurements realized 5 months apart, which reflects the consistency of this trait over time. As typical soil inhabitants, the harvestman P. paessleri present a lower metabolic rate in comparison with arthropods of similar body mass (e.g. arachnids). Although the coefficient of thermal sensitivity is within of the range reported for arthropods inhabiting Mediterranean zones, it is lower than expected for an organism with such a low SMR. This appears to be the first report of repeatability of metabolic rate in a harvestman species.     

Competition between hummingbirds and bumble bees for nectar in flowers of Impatiens biflora

Summary Using removal experiments and concurrent measurement of resource levels, evidence was obtained for exploitation competition between Ruby-throated hummingbirds and two bumble bee species (Bombus fervidus and B. vagans) foraging for nectar on Impatiens biflora.When all three species were active, flower visitors showed a complex pattern of resource partitioning involving both diel and spatial changes. Hummingbirds foraged almost exclusively from the outermost exposed flowers on plants from which they drained nectar levels beyond the reach of bees over most of the day. In contrast the longtongued bee species (B. fervidus), and the shorter-tongued B. vagans, displayed a preference for the innermost flowers on plants which were protected from hummingbird visitation by surrounding vegetation. The two Bombus spp. began foraging at different times during the day: B. vagans were most active in early morning but were replaced by B. fervidus later in the day.When hummingbirds were rare, only B. fervidus showed evidence of competitive release: an increase in the number of foragers and a broadening of flower choice to include more outer flowers. Workers of B. vagans showed a similar response to temporary removal of B. fervidus and also extended their foraging over the entire day. These responses were consistent with changes in the availability of nectar to different species.Removal experiments demonstrated that individuals of one species can be largely excluded from access to nectar resources as a direct result of exploitation of nectar by foragers of other species with longer tongues. Thus in this system interspecific exploitation is an important mechanism involved in resource partitioning.     

GENOME RELATIONSHIPS IN INTERSPECIFIC AND INTERGENERIC HYBRIDS OF RENANTHERA

Kamemoto , H., and K. Shindo . (U. Hawaii, Honolulu.) Genome relationships in interspecific and intergeneric hybrids of Renanthera. Amer. Jour. Bot. 49(7): 737–748. Illus. 1962.—Chromosome numbers and meiotic behavior of species and hybrids of Renanthera (Orchidaceae) were investigated. Renanthera elongata, R. histrionica, R. matutina, R. monachica, and R. storiei were diploid (2n = 38). The race of R. coccinea commonly grown in Hawaii was found to be hexaploid (2n = 114), while a recently introduced clone from Thailand was diploid (2n = 38). Diploid interspecific hybrids formed about 18 bivalents at M-I, indicating a relatively strong homology of parental chromosomes. The tetraploid hybrid of diploid R. monachica and hexaploid R. coccinea showed predominantly 37 or 38 bivalents, indicating good homology of genomes of the 2 parental species, and autosyndetic pairing in the 2 additional genomes of R. coccinea. Intergeneric hybrids involving Renanthera spp. could be classified into 2 distinct groups: those with 14–11 bivalents that are generally oriented at the metaphase plate and eventually lead to a preponderance of tetrads or tetrads with microcytes, and those with fewer bivalents (9–5) many of which are unoriented pseudobivalents and which ultimately give rise to dyads and dyads with microcytes. Relationships of parental species on a taxonomic basis are closer in the former than the latter group.     

Low metabolic rate in a nocturnal desert lizard,an arbylus switaki murphy (Sauria: Gekkonidae)

• 1.1. Metabolic rates were measured in two xeric-adapted gekkonid lizards, Anarbylus switaki sind Coleonyx variegatus.
• 2.2. Standard metabolic rates (SMR) were 0.074 ml O₂/g hr in A. switaki and were 70% of the value predicted on the basis of mass from regression equations. The SMR of 0.146ml O₂/ghr in C. variegatus is similar to the predicted value for a lizard of this mass.
• 3.3. During intense activity, metabolic rates of 0.378 and 0.804ml O₂/g hr were measured in A. switaki and C. variegatus, respectively.
• 4.4. Various theories to explain reduced SMR in lizards are discussed, and it is concluded that none is entirely satisfactory, and caution should be exercised in interpreting the adaptive significance of reduced SMR.

     

Comparative nectar-foraging behaviors and efficiencies of an alien and a native bumble bee

Resource preemption by alien organisms can contribute to their invasion success and the demise of functionally equivalent native species, particularly when opportunistic foraging by aliens results in more efficient exploitation. In forests of NW Patagonia, the only native bumble bee and major pollinator, Bombus dahlbomii, declined almost to extinction as the alien B. ruderatus increased in abundance since its first appearance about 17 years ago. To explore whether resource competition might have driven this displacement we studied the behavior and foraging efficiency of both bumble bees while they harvested nectar from flowers of Alstroemeria aurea, the main summer food resource in the forests of NW Patagonia. We compared the nectar content of flowers that bees selected, recently visited, and rejected with that of randomly-chosen neighboring flowers and assessed differences in visitation rates. The native bumble bee selects flowers with abundant nectar and mostly exploits nectar-rich flower patches by rejecting a higher proportion of flowers with little or no nectar. On the other hand, the alien bumble bee discriminated less with respect to sugar content per visited flower, but visited more flowers per minute. Workers of the native bumble bee harvested ~70% more sugar per unit of time than those of the alien species in absolute terms, and a similar amount when sugar harvested was expressed as a percentage of body mass. In contrast to expectation, the opportunistic foraging of the alien bumblebee was not more efficient and therefore cannot explain the ecological extinction of the native species through exploitative competition. These findings suggest that the displacement of the native species by the alien may be driven by other factors, such as the associated introduction of novel diseases or parasites.     

Characteristics of floral nectaries and nectar in two species of Crataegus (Rosaceae)

 The structure of floral nectaries of Crataegus coccinea and C. crus-galli was examined using light and scanning electron microscopy. The radial length of the floral nectary, measured from longitudinal sections of flowers, was 30% larger in C. crus-galli than in C. coccinea. For both Crataegus species the glandular tissue thickness was similar – approx. 400 μm. Also, the number of stomata per mm² of nectary surface in C. crus-galli was much higher (by 43%) than for C. coccinea. Stomata were situated in deep hollows. For both taxa the period of nectar secretion was 4 days. The mean quantity of total sugar in nectar per 10 flowers of C. crus-galli and C. coccinea was 3.87 mg and 0.33 mg, respectively. Received August 28, 2002; accepted December 17, 2002 Published online: June 2, 2003     

The postabsorptive and postprandial metabolic rates of praying mantises: Comparisons across species,body masses,and meal sizes

The metabolic rate of an animal affects the amount of energy available for its growth, activity and reproduction and, ultimately, shapes how energy and nutrients flow through ecosystems. Standard metabolic rate (SMR; when animals are post-absorptive and at rest) and specific dynamic action (SDA; the cost of digesting and processing food) are two major components of animal metabolism. SMR has been studied in hundreds of species of insects, but very little is known about the SMR of praying mantises. We measured the rates of CO₂ production as a proxy for metabolic rate and tested the prediction that the SMR of mantises more closely resembles the low SMR of spiders – a characteristic generally believed to be related to their sit-and-wait foraging strategy. Although few studies have examined SDA in insects we also tested the prediction that mantises would exhibit comparatively large SDA responses characteristic of other types of predators (e.g., snakes) known to consume enormous, protein-rich meals. The SMR of the mantises was positively correlated with body mass and did not differ among the four species we examined. Their SMR was best described by the equation μW = 1526 * g^0.745 and was not significantly different from that predicted by the standard ‘insect-curve’; but it was significantly higher than that of spiders to which mantises are ecologically more similar than other insects. Mantises consumed meals as large as 138% of their body mass and within 6–12 h of feeding and their metabolic rates doubled before gradually returning to prefeeding rates over the subsequent four days. We found that the SDA responses were isometrically correlated with meal size and the relative cost of digestion was 38% of the energy in each meal. We conclude that mantises provide a promising model to investigate nutritional physiology of insect predators as well as nutrient cycling within their ecological communities.     

Size-dependent morphology of the conductive bronchial tree in four species of myomorph rodents

Size-dependent structural patterns in the conductive bronchial tree of four species of myomorph rodents of different body weight were determined by lung casts. The lungs of the harvest mouse, Micromys minutus, body weight 5–7 g, the house mouse, Mus musculus, body weight 35–45 g, the brown rat, Rattus norvegicus, body weight 200–400 g, and the African giant pouched rat, Cricetomys gambianus, body weight 1,200–1,800 g, were inflated to 20 cm H₂O, frozen, freeze-dried, hardened, and filled with silicone rubber. The casts were pruned, and branching pattern, diameter, and volume of the conductive bronchial tree were determined using a binocular magnifier. All four species have four lobes on the right lung and an undivided left lung, and the central bronchial tree on either side shows an identical monopodial branching pattern. Although the ramification of the central conductive bronchi is not size-dependent, the diameter and volume are. The diameter of the left main bronchus equals 1.24% of body length in Micromys and 0.6% in Cricetomys, and the conductive bronchial tree makes up 13% of the total lung volume in Micromys and 6% in Cricetomys. Relatively wider airways and a decline in airway resistance with declining body mass in small mammals compared to large ones result in a high ventilatory dead space, which is compensated for by a higher breathing frequency. © 1996 Wiley-Liss, Inc.     

Efficiency of facultative frugivory in the nectar-feeding bat Glossophaga commissarisi: the quality of fruits as an alternative food source

The efficiency of food exploitation correlates positively with the extent of dietary specialization. Neotropical nectar-feeding bats (Glossophaginae) have one of the most specialized diets among mammals, as floral nectar constitutes a sugar-rich and highly digestible but protein and fiber depleted food source. However, dietary constraints, such as a temporary scarcity of nectar, or protein demands may sometimes require the uptake of alternative food items. We investigated the influence of a diet switch from nectar to fruit on intestinal morphology, body mass, and energy budget in the nectar-feeding bat Glossophaga commissarisi and quantified feeding efficiency. We hypothesized that these nectar specialists depend on a constant supply of nectar, if they were lacking the ability for morphological and physiological plasticity in response to a fiber-rich diet. Although capable of harvesting infructescences of Piper hispidum, G. commissarisi was less efficient in extracting energy from fruits (48% digestive efficiency of total fruit energy content) than from nectar (c. 99% digestive efficiency). The intestinal morphology and organ masses did not change after bats were switched from nectar to fruits. Captive bats exhibited lower daily energy expenditures and flight activity when feeding on fruits than during nectarivory. Possibly, this may have been a deliberate regulation to balance reduced feeding efficiency, or simply the consequence of extended digestive pauses. The low digestibility of Piper, in combination with slow digestion and the bats’ inability for morphological and physiological plasticity may cause nectar-feeders to reduce their maximum energy expenditure when feeding on fruits. We argue that although fruits may substitute for nectar, they may cause restricted maximum energy assimilation compared with nectar.     

Effects of elevated CO2 on flowering phenology and nectar production of nectar plants important for butterflies of calcareous grasslands

Effects of elevated CO₂ on flowering phenology and nectar production were investigated in Trifolium pratense, Lotus corniculatus, Scabiosa columbaria, Centaurea jacea and Betonica officinalis, which are all important nectar plants for butterflies. In glasshouse experiments, juvenile plants were exposed to ambient (350 μl l⁻¹) and elevated (660 μl l⁻¹) CO₂ concentrations for 60–80 days. Elevated CO₂ significantly enhanced the development of flower buds in C. jacea. B. officinalis flowered earlier and L. corniculatus produced more flowers under elevated CO₂. In contrast, the number of flowers decreased in T. pratense. The amount of nectar per flower was not affected by elevated CO₂ in the tested legumes (T. pratense and L. corniculatus), but was significantly reduced (!) in the other forbs. Elevated CO₂ did not significantly affect nectar sugar concentration and composition. However, S. columbaria and C. jacea produced significantly less total sugar under elevated CO₂. The nectar amino acid concentration remained unaffected in all investigated plant species, whereas the total of amino acids produced per flower was reduced in all non-legumes. In addition, the amino acid composition changed significantly in all investigated species except for C. jacea. The observed effects are unexpected and are a potential threat to flower visitors such as most butterflies which have no alternative food resources to nectar. Changes in nectar production due to elevated CO₂ could also have generally detrimental effects on the interactions of flowers and their pollinators. Received: 12 September 1996 / Accepted: 9 September 1997     

Effects of meal size,meal type,and body temperature on the specific dynamic action of anurans

Specific dynamic action (SDA), the increase in metabolism stemming from meal digestion and assimilation, varies as a function of meal size, meal type, and body temperature. To test predictions of these three determinants of SDA, we quantified and compared the SDA responses of nine species of anurans, Bombina orientalis, Bufo cognatus, Ceratophrys ornata, Dyscophus antongilli, Hyla cinerea, Kassina maculata, Kassina senegalensis, Pyxicephalus adspersus, and Rana catesbeiana subjected to meal size, meal type, and body temperature treatments. Over a three to seven-fold increase in meal size, anurans experienced predicted increases in postprandial rates of oxygen consumption the duration of elevated and SDA. Meal type had a significant influence on the SDA response, as the digestion and assimilation of hard-bodied, chitinous crickets, mealworms, and superworms required 76% more energy than the digestion and assimilation of soft-bodied earthworms, waxworms, and neonate rodents. Body temperature largely effected the shape of the postprandial metabolic profile; peak increased and the duration of the response decreased with an increase in body temperature. Variation in body temperature did not significantly alter SDA for four species, whereas both H. cinerea and R. catesbeiana experienced significant increases in SDA with body temperature. For 13 or 15 species of anurans ranging in mass from 2.4 to 270 g, SMR, postprandial peak and SDA scaled with body mass (log–log) with mass exponents of 0.79, 0.93, and 1.05, respectively.     

Nectar Production of Two Sympatric Species of Columnar Cacti

We examined the potential for exploitation competition by differential attractiveness in two sympatric species of columnar cacti on Curaçao, Netherlands Antilles. Stenocereus griseus and Subpiloccreus repandus have temporally overlapping flowering phenologies and share pollinators. We examined nectar volume, energy contents, and sugar ratios for the entire night and at two-hour intervals in both cactus species. Except for a burst in nectar volume and sugar concentration by Subpilocereus repandus during the first two hours of anthesis, nectar secretion patterns, energy contents, and sugar ratios (70% hexose) were similar for the two species. The standing crops of nectar in both species were kept very low by bat pollinators. We suggest that the potential for exploitation competition between Stenocereus griscus and Subpilocereus repandus is currently very low on Curapo.     

Comparisons of body sizes at sexual maturity and at sex change in the parrotfishes of Hawaii: input needed for management regulations and stock assessments

First estimates of sex allocation patterns and body size‐at‐sexual maturity and at protogynous sex change are presented for the five major (including one endemic) species of parrotfishes of Hawaii. Median body size at initial maturation as a female (L_M50) and at protogynous sex change from adult female to adult male (L_Δ50) varied greatly among the five species. Estimates of L_M50 were about 14, 17, 24, 34 and 35 cm fork length (L_F) in palenose Scarus psittacus, Pacific bullethead Chlorurus spilurus, stareye Calotomus carolinus, spectacled Chlorurus perspicillatus and redlip parrotfish Scarus rubroviolaceus. Values of L_Δ50 were c. 23, 27, 37, 46 and 47 cm L_F in the respective species. Length at female maturation was proportional to maximum body size (L_max) of the respective species, ranging from 50 to 72% and averaging 62% of L_max across species. L_Δ50 was also proportional to L_max, ranging from 82 to 97% and averaging 92%. Males of both pairs of Scarus and Chlorurus spp. reported here are diandric. Only one of the five major species (C. carolinus) is functionally monandric, with either all or nearly all males secondarily derived from adult females. The broadly differing absolute body sizes at sexual maturation and at sex change among the five species have important implications for improving regulatory size limits for parrotfishes in the State of Hawaii, where parrotfish species have historically been managed based on a single minimum size limit of 30·5 cm L_F. This study provides a model demonstration of why catch data for parrotfishes, and other size‐structured reef‐fish populations, should be recorded either by species or by functional size‐groups of species that allow setting more meaningful minimum size limits.     

Metabolic rate and growth potential of various tilapias

Tilapia species and their hybrids had Mo₂ s between 44.4 and 84.2 mg kg^-0.8d^-1 at comparable temperatures. With one exception (O. aureus times S. galilaeus), the standard metabolic rate (SMR) tended to be higher than that of the purebred species. The scope for spontaneous activity (SSA) was a good measure of the energy available to the fish for body tissue synthesis. Using the amount of oxygen that is consumed above standard needs (SMR), theoretical growth potentials of 9.0 to 27.3 g kg^-0.8d^-1 were derived. It is concluded that SSA may be used for selection of species for aquaculture.     

Demographics of Lagocephalus inermis in the Arabian Sea unveils complex conservation challenges

The first assessment of the demographics of Lagocephalus inermis, a species associated with pufferfish bites and fishing down the food web in the Arabian Sea, south-west coast of India, was performed based on length structured population dynamics of 1601 individuals caught in commercial fisheries. Analysis revealed that the current level of exploitation is 90% of the predicted exploitation producing maximum relative yield per recruit (E_max), suggesting high levels of exploitation with potential for significant negative consequences for trophic cascades.