The early life history of kurosoi,Sebastes schlegeli (Scorpaenidae), in the Sea of Japan

Larval and juvenile stages of kurosoi,Sebastes schlegeli, are described and illustrated from wild specimens. Some ecological aspects of larvae and juveniles are also described. Notochord flexion occurred between 5.6–7.5 mm SL. Transformation occurred between 13–20 mm SL. Preflexion and flexion larvae ofS. schlegeli can be distinguished from similar larvae by the pigmentation of the dorsal and ventral midlines of the tail and absence of pigmentation on the ventral portion of the rectum. After notochord flexion, the dorsal and lateral regions in both larvae and pelagic juveniles were heavily pigmented, suggesting adaptation for neustonic life style. Larvae and juveniles were caught at many coastal stations, but did not occur in cooler offshore waters. Larvae smaller than 20 mm SL inhabited surface waters. Until ca. 40 mm SL, juveniles inhabited mainly surface waters (without drifting seaweed), but also used other habitats, such as the drifting seaweed, and near the sea bed. Small larvae (<7 mm SL) fed mainly on copepod nauplii. Larger larvae fed on calanoid copepodites andEvadne nordmanni. Pelagic juveniles fed mainly on fish eggs, with fish larvae also being important food items for some individuals. Most food items taken by juveniles that were associated with drifting seaweed were eggs with attaching filaments (Cololabis saira andHyporhamphus sajori), suggesting that the high density of such food items both attracts and keeps juveniles around drifting seaweed.     

Ontogeny of turbiditaxis in hatchery‐reared Japanese anchovy Engraulis japonicus

The ontogenetic change in turbiditaxis (i.e. attraction to turbid waters) was examined in the larvae and juveniles of Japanese anchovy Engraulis japonicus by testing three levels of turbidity (0, 20 and 100 ppm of kaolin). Larvae of 12, 20 and 30 mm standard length (L_S) exhibited turbiditaxis to both 20 and 100 ppm of kaolin, whereas 6 mm L_S larvae and 45 mm L_S juveniles did not exhibit any turbiditaxis. Turbiditaxis might explain the ontogenetic habitat shift from coastal to offshore waters reported for this species.     

The diet of king eiders wintering in Nuuk,Southwest Greenland,with reference to sympatric wintering common eiders

Coastal and offshore waters of Southwest Greenland are internationally important wintering areas for king eiders (Somateria spectabilis) breeding in eastern Canadian Arctic and in northwestern Greenland. This paper presents the first assessment of their winter diet. Based on esophageal-proventricular samples from 26 females (13 juveniles and 13 older birds) and 15 males (11 juveniles and four older birds) collected in 2000–2002 (November–May) in coastal waters of Nuuk, we identified 28 prey species. The diet consisted of almost equal proportions (aggregate fresh mass) of polychaetes, echinoderms, crustaceans and molluscs. The dominant prey species were Pectinaria spp. (26.8%), Strongylocentrotus droebachiensis (18.4%), Mya eideri (11.2%) and Hyas araneus (9.7%). The polychaetes have previously been identified as important prey for eiders in Greenland, but apparently not outside Greenland. Compared with a diet study of common eiders Somateria mollissima from the same wintering area, the king eiders consumed significantly less bivalves and significantly more echinoderms. This difference corresponded with observations that common eiders were feeding in shallow waters, while king eiders were feeding in deeper waters farther from the shore. Benthic surveys are needed to confirm that diet corresponds with prey availability.     

Demonstration of migration of juvenile cyprinid fish using parasite biomarkers

Migration of juvenile (0+) cyprinid fish from the Kiso River to experimental streams in the Aqua Restoration Research Center was demonstrated by the presence of parasites on fish. The experimental streams were located a minimum of 0.7 km from the main reach of the Kiso River, and they were connected via a tributary (Shinsakai River). The experimental streams were used as a spawning site and a nursery for juveniles, similar to the use of a temporary water body such as a paddy field. A digenean trematode (Centrocestus spp.) and the glochidia of unionid bivalves, both of which did not infect fish in the experimental streams or in the Shinsakai River, were used as marker parasites. Their presence indicated that the fish moved in the experimental streams from the Kiso River. For both fish species (Gnathopogon elongatus and Zacco platypus) assessed in this study, juveniles greater than 20–30 mm standard length could migrate from the Kiso River. This study showed that temporary waters are important as a nursery for juvenile fish, for whether or not a species spawns there. For the conservation of fish populations, it is important that temporary waters that are used as a nursery are connected with a permanent water area by a channel, through which not only adults, but also juvenile fish can migrate.     

Biology of the threespine stickleback,Gasterosteus aculeatus,and the blackspotted stickleback,G. wheatlandi,during their marine pelagic phase in the Bay of Fundy,Canada

Synopsis Two species ofGasterosteus were collected from the surface waters of 48 stations in the Bay of Fundy from 1979–1982. Densities varied widely according to locality and time of year (range: 1 fish 0.2 m^–2 to 1 fish 26.3 m^–2 of sea surface) but peaked within 30 km of the New Brunswick/Maine coast in July and August. A few adults were caught as far as 100 km from the coast in winter. Guts ofG. wheatlandi were significantly fuller (63.3 ± 0.6%) than those ofG. aculeatus (44.6 ± 0.1%) but there were no differences between male and female guts within species. Quantitatively, gut contents were very similar between species, consisting primarily of (99.4%): calanoid copepods (Centropages typicus Kroyer andEurytemora cfamericana Williams), copepod nauplii, cladocerans (Podon leuckarti Sars andP. polyphemoides Leuckart) and planktonic eggs (in decreasing order of importance).Gasterosteus wheatlandi ate significantly more calanoids thanG. aculeatus but all other prey types were eaten in similar amounts. Within species, there were no differences in the numbers of each prey type eaten over time. The most abundant calanoid species caught alongside the fishes in the sampling nets did not occur in the sticklebacks' diets; probably they were too large to be ingested.Gasterosteus aculeatus bred in inshore, brackish water ponds in late April. By late July most juveniles had migrated out into the Bay but a few remained until early September.Gasterosteus wheatlandi bred later in the brackish water ponds (late May) and juveniles began migrating into the Bay in early August; a few remained in the ponds until early September. Adults were found in the Bay alongside juveniles suggesting that individuals of both species may survive for a second year. In both species, growth rates of juveniles were greater in brackish water than in the sea.     

Population demographics of Palaemon peringueyi (Macpherson 1990) (Decapoda: Palaemonidae) in a small intermittently open Eastern Cape estuary

The population demographics of the caridean shrimp Palaemon peringueyi was investigated monthly at four sites over a period of one year in the small, intermittently-open Grants River Estuary situated on the south-east coastline of southern Africa. Mean total abundance and biomass of P. peringueyi ranged between 0 and 23.2 ind m^?2 and 0 and 2.3mg wwt m^?2, respectively. A peak in its abundance coincided with a breaching event that occurred in December 2004, and could be attributed to the mass recruitment of juveniles (carapace length <9mm) into the estuary. Minor peaks in abundance were also associated with marine waters overtopping the sandbar that separates the estuary from the marine environment. The highest biomass values were recorded when the estuary was separated from the sea. Maximum abundance and biomass values of P. peringueyi were generally recorded in the middle reaches of the estuary where extensive beds of submerged vegetation, mainly Potamogeton pectinatus, predominated. Pearson correlation analysis indicated that the total abundance of P. peringueyi was significantly correlated (r = 0.49; p < 0.05) to percentage cover of submerged vegetation. The spatial pattern in abundance and biomass values of the shrimp is thought to reflect the availability of refuge areas against predation. A distinct spatial pattern in the community structure of the shrimp was evident, with juveniles numerically dominating the samples in the lower reaches of the estuary, while mature females predominated in the upper reaches of the system. In the middle reaches, the community comprised both juveniles and adults.     

Geographical distribution and abundance of postlarval and juvenile Pleuragramma antarcticum (Pisces,Notothenioidei) off the Antarctic Peninsula

Summary The early life history of Pleuragramma antarcticum off the Antarctic Peninsula is described from extensive material collected during four expeditions between 1975/76 and 1982 by means of an RMT 1+8. Postlarvae occurred frequently on the northern continental shelf in February and March except during the 1977/78 season when they were almost absent. Abundance varied mainly between 1.8 and 14.7 postlarvae per 10³ m³ with maxima between 32.6 and 143.3 per 10³ m³. Juveniles were less abundant with 0.1–4.9 and maxima between 9.8 and 28.3 per 10³ m³, but formed a consistent, predominant proportion (83–97%) of the pelagic juvenile fish fauna throughout the years of the study. They were distributed over the whole Bransfield Strait and adjacent waters in the top 200 m. Postlarvae and juveniles showed different patterns of vertical distribution; more than 70% of postlarvae occurred in the top 135 m of the water column whereas 83% of juveniles were encountered between 70 and 200 m with increasing abundance towards the lower depth. Three length groups were identified corresponding to age groups 0, 1, and 2. Hatching was estimated to occur in December. Postlarval distribution patterns and the prevailing transport of water masses suggest that coastal waters south of the tip of the Antarctic Peninsula and in the north-eastern Bellingshausen Sea are probable spawning areas. The Bransfield Strait and adjacent waters represent nursery grounds for the early stages of P. antarcticum from these sites.     

Identification of small juvenile scombrids from northwest tropical Australia using mitochondrial DNA cytochrome <Emphasis Type="Italic">b</Emphasis> sequences

Small juveniles of the nine species of scombrids in Australian waters are morphologically similar to one another and, consequently, difficult to identify to species level. We show that the sequence of the mitochondrial DNA cytochrome b gene region is a powerful tool for identification of these young fish. Using this method, we identified 50 juvenile scombrids collected from Exmouth Bay, Western Australia. Six species of scombrids were apparent in this sample of fish: narrow-barred Spanish mackerel (Scomberomorus commerson), Indian mackerel (Rastrelliger kanagurta), frigate tuna (Auxis thazard), bullet tuna (Auxis rochei), leaping bonito (Cybiosarda elegans), and kawakawa (Euthynnus affinis). The presence of Indian mackerel, frigate tuna, leaping bonito, and kawakawa is the first indication that coastal waters may be an important spawning habitat for these species, although offshore spawning may also occur. The occurrence of small juvenile S. commerson was predicted from the known spawning patterns of that species, but other mackerel species (Scomberomorus munroi, Scomberomorus queenslandicus, Scomberomorus semifasiciatus) likely to be spawning during the sampling period were not detected among the 50 small juveniles analyzed here.     

Importance of the upper estuary as a nursery ground for fishes in Ariake Bay,Japan

To examine the importance of the upper estuarine areas of Ariake Bay as a nursery ground for fish, assemblages of larvae and juveniles were compared among various aquatic habitats. The upper estuaries of the bay (the Rokkaku and Hayatsue estuaries) are brackish, highly turbid waters with high tidal velocities, and differ substantially from the Isahaya area, which has been separated from the bay by a man-made dike, to the middle estuary (the Kikuchi estuary). Abundances of larvae and juveniles were higher in the estuaries than in the open bay and Isahaya areas. Abundant species in the upper estuaries were similar to each other, but differed from those of the middle estuary. This was primarily due to larvae and juveniles of fishes that occurred almost entirely in the upper estuaries, such as Acanthogobius hasta, Boleophthalmus pectinirostris, Coilia nasus, Cynoglossus abbreviatus, Nibea albiflora, Odontamblyopus lacepedii, Trachidermus fasciatus and Tridentiger barbatus. These results suggest that the upper estuaries play an important role as nursery grounds for fishes.     

Observations on the pathogenicity of Pasteuria penetrans, a parasite of root-knot nematodes

A simple test was used to determine whether or not Pasteuria penetrans spores would attach to 17 species of nematodes. All susceptible individuals had spores attached to their cuticles after 24 h of gentle agitation in suspensions containing 10⁵spores/ml. Spores of P. penetrans from six populations of Meloidogyne only adhered to species of Meloidogyne and they adhered in greatest numbers to the species from which they had been originally isolated. Sonication of spores from infected females increased attachment but the effect was dependent on pH and whether the test was conducted in tap or distilled water. Invasion of tomato roots was reduced by up to 86% when, rather than using healthy juveniles, second-stage juveniles bearing 15 or more spores were added to soil at high densities (1000 or 3000/plant); at low densities (500/plant) invasion was not significantly affected. The rate of development of M. incognita juveniles infected with P. penetrans was slower than that of healthy juveniles. The numbers of second-generation of M. incognita were reduced by 82–93% when juveniles encumbered with 1–15 spores were added to soil instead of those bearing no spores. Pasteuria penetrans populations differed in their aggressiveness and when juveniles encumbered with the same number of spores from two populations were added to soil there were differences in the numbers of females that became infected. The implications of these results for the development of P. penetrans as a biological control agent are discussed.     

HYBRIDIZATION OF SYMPATRIC PATIRIELLA SPECIES (ECHINODERMATA: ASTEROIDEA) IN NEW SOUTH WALES

Three species of the asteroid genus Patiriella occur sympatrically in New South Wales and the possibility for hybridization among them was examined through a series of cross-fertilization experiments. Patiriella calcar and P. gunnii are morphologically distinct as adults but indistinguishable as larvae. Patiriella exigua is morphologically distinct in both its adult and larval morphologies. The gametes of P. calcar and P. gunnii were reciprocally compatible: laboratory crosses between these species produced viable hybrid juveniles. In crosses between female P. calcar and male P. gunnii, most of the juveniles metamorphosed with an arm number intermediate between that of the parents, whereas crosses between female P. gunnii and male P. calcar produced juveniles with an arm number more similar to the maternal phenotype. Heterospecific crosses with P. exigua resulted in low fertilization rates, and viable hybrids were not produced. This species appears capable of self-fertilization. Because hybrids between P. calcar and P. gunnii were viable, neither gametic incompatibility nor hybrid inviability appears to ensure reproductive isolation between these species. Ecological or habitat segregation and temporal separation in breeding may isolate these species in the field. The results demonstrate that if gamete surface recognition molecules are involved in fertilization of P. calcar and P. gunnii, then they are not strongly species specific, at least at the sperm concentrations used in this study. Reproductive isolation between these species has evolved despite their gametic compatibility. In contrast, P. exigua is isolated from its congeners because of gametic incompatibility and several features characteristic of its reproduction and development. The implications of these findings for reproductive isolation and speciation of Patiriella and for the evolution of reproductive isolation in free-spawning marine organisms are discussed.     

Ontogenetic habitat preferences of the narrownose smooth-hound shark, Mustelus schmitti, in two Southwestern Atlantic coastal areas

The aim of this study was to determine the ontogenetic habitat preferences of the narrownose smooth-hound shark, Mustelus schmitti, in Río de la Plata and El Rincón coastal areas. There, canonical correspondence analyses of fishery research survey data showed that M. schmitti ontogenetic stages were differentially affected by depth, temperature and salinity. Neonates and juveniles were more abundant and remain in nearshore waters, suggesting the presence of nursery areas in which food availability and environmental conditions allow a faster growth. Adults M. schmitti presented different environmental associations mainly associated with depth and temperature. During non-reproductive season they were associated with deeper coastal waters. With the arrival of the reproductive season, adults migrate from deep to nearshore waters and show sexual segregation associated with pre- or post-mating behaviors. Hence, the year-round presence of neonates and juveniles and the seasonal occurrence of adults in nearshore waters make this habitat essential to M. schmitti population dynamics since key ontogenetic stages will be vulnerable if a direct impact occurs there.     

Distribution of sawfishes (Pristidae) in the Queensland Gulf of Carpentaria,Australia, with notes on sawfish ecology

Synopsis Pristis microdon, P. zijsron, P. clavata and Anoxypristis cuspidata are distributed throughout the Queensland section of the Gulf of Carpentaria, Australia. In a survey of the four species, Anoxypristis cuspidata was the most abundant and was recorded in both the inshore and offshore set net fisheries. The size distribution and catch locations of A. cuspidata suggest that the inshore area to a depth of 10 m may be the preferred habitat for juveniles of this species, while adults primarily occur offshore. Pristis microdon, P. zijsron and P. clavata were recorded only in the inshore fishery with catches dominated by immature animals. Pristis microdon was caught in the inshore fishery late in the monsoonal wet season (February to April) and inhabited both freshwater and estuarine environments. Pristis zijsron occurred only on the sand and mud flats outside river mouths whilst P. clavata inhabited both the sand and mud flats and upstream estuarine habitats. Observations on reproductive staging and the capture of neonate specimens suggest that in all four pristids, pupping occurred through the wet season until the beginning of the dry season in May. A seasonal set net closure for the barramundi, Lates calcarifer and shark fisheries, which has been in place since 1980 in Queensland Gulf waters, therefore offers a measure of protection to breeding female sawfish and their offspring.     

Early morphological development ofOmobranchus fasciolatoceps andO. Punctatus (Blenniidae: Omobranchini) reared in an aquarium

Larval and juvenile development of two blenniids,Omobranchus fasciolatocepts andO. punctatus, is described using eggs collected from natural waters in Tokyo Bay and incubated in an aquarium. These larvae and juveniles are compared with those of two otherOmobranchus species,O. elegans andO. loxozonus, distributed widely in Japan.Onobranchus punctatus is characterized by a unique, pointed snout in preflexion larvae, no melanophores proximally on the lower part of the pectoral fins in flexion and postflexion larvae, and pterygiophores projecting externally as blades between the dorsal and anal fin-rays in postflexion larvae and juveniles.Omobranchus fasciolatoceps has the following characteristics: a few melanophores on the fore-and mid-brain, but none on the hind-brain in preflexion larvae; no melanophores on the cleithral symphysis in flexion and postflexion larvae; no external pterygiophore blades in postflexion larvae and juveniles; and a unique dorsal skin flap on the head in juveniles. Ontogenetic developement of dorsal and anal pterygiophores is described forO. fasciolatoceps andO. punctatus. InO. punctatus, the postero-distal part of each proximal radial projects remarkably to form the external blades between the soft fin-rays, whereas the external blades between the fin spines are formed by fusion of a dermal bone developed from the antero-distal part of each proximal radial with the adjacent distal radial.     

Length–length relationship, length–weight relationship, gonadosomatic index, condition factor, size at maturity and fecundity of Parastromateus niger (Carangidae) in Kuwaiti waters

Analyses of morphometric parameters of the black pomfret, Parastromateus niger, in the Kuwaiti waters of the Arabian Gulf during a 44‐month study revealed the following length‐length relationships: TL (cm) = 0.63 + 1.15SL (females), TL (cm) = 0.94 + 1.14SL (males) and TL (cm) = 0.75 + 1.15SL (both sexes including juveniles). The 95% CI of the exponent in length‐weight relationship varied from 2.788 to 2.796 in females, 2.726 to 2.732 in males, 2.779 to 2.784 for both sexes and 2.590 to 2.613 in juveniles, all indicating an allometric relationship. Simultaneous analysis of Fulton’s condition factor (K) and GSI indicate that spawning in black pomfret peaks in May and June even though the fish remain in good condition throughout the spawning season. The Fulton’s condition factor was statistically discriminatory in determining the well‐being of P. niger. Variation in average maximum condition was significant between sexes and also higher in 2004 as compared to 2005. The mean size at first sexual maturity (SL_50%) was 17.5 cm for males and 29 cm for females. Fecundity ranged from 71 305 to 3 895 449 eggs and correlated positively with: (a) ovary‐free body weight (P < 0.05), standard length (P < 0.05) and ovary weight (P < 0.05), and negatively with egg size (P > 0.05). Fecundity‐total length relationship was best described by the logarithmic equation of the form F = 0.898 + 3.15 × TL^3.15. The use of results of such morphometric studies in the management of the P. niger species in the Arabian Gulf is suggested due to its growing commercial importance.     

Spatial distribution and life‐history aspects of blackspot seabream Pagellus bogaraveo (Osteichthyes: Sparidae)

Spatial distribution and life history aspects of Pagellus bogaraveo in the eastern Ionian Sea were investigated using the data from 13 different studies carried out in the area from 1983 to 2010. The spatial patterns of the abundance, biomass and mean size showed that the species inhabits the shallow waters of the shelf (<170 m depth) as juveniles up to a certain size (<180 mm total length, L_T), moving to deeper waters of the slope (mainly 400–500 m depth) as adults. The spatial pattern of abundance indicated a continuous distribution of the species in deep waters, with hot‐spot areas of high values, whereas in shallow waters distribution was more discontinuous, with higher concentrations of juveniles in estuaries and brackish waters. The study of biological aspects of the species revealed (1) a difference in the increase in mass between males and females, (2) protandrous hermaphroditism, accompanied by the presence of primary females and males that do not change sex, (3) a sex ratio in favour of females >250 mm L_T, (4) the presence of hermaphrodites between 200 and 370 mm, (5) a long reproduction period from June to March, (6) a size at first maturity around 300 mm and (7) a diet composition of adults based mainly on fishes, and also on opportunistic behaviour in the food scarce environment of deep waters. The results suggest that the species' distribution and feeding strategies are the most appropriate for the oligotrophic eastern Ionian waters and that these conditions result in smaller sizes of the species in the east Mediterranean Sea compared to the west basin and the east Atlantic Ocean, with implications for the growth and reproductive biology of the species.     

Allocation strategies in crustacean stoichiometry: the potential role of phosphorus in the limitation of reproduction

1. Elemental composition (carbon : nitrogen : phosphorus, C : N : P) was analysed in eggs and juveniles of two crustaceans, Daphnia magna (Cladocera) and the crayfish Astacus astacus (Decapoda). Stoichiometry was also analysed for the carapace, muscle tissue, hepatopanchreas and gills of Astacus. 2. For both species the C : P ratio was significantly higher in eggs than juveniles, but there was a constant, homeostatic elemental ratio in eggs during embryogenesis (Astacus) and with different C : N : P in maternal food (Daphnia). 3. Differences in the stoichiometry of major tissue categories in Astacus suggest that there are distinct allocation strategies of elements to various somatic tissues as well as to reproduction versus somatic tissues overall. 4. There are strong ontogenetic shifts in the allocation of energy and elements in both species, as for crustaceans in general. During maturity there may be a trade‐off with regard to the allocation of C, N or P to somatic or reproductive tissue, and poor food quality (high C : P in food) could pose other constraints on reproductive capacity than does food shortage (low C). 5. Egg production may be at least as sensitive to low P as is somatic growth and could result in a marked decrease in overall population growth rate more severe than would be expected from individual growth rate alone.     

A nursery Area for Sharks and Rays in Northeastern Brazil

Synopsis Elasmobranch nurseries are habitats where females give birth to their young and juveniles spend their early life history. Hypotheses concerning nurseries suggest that these provide the young a better source of food and protection against predation, however the degree of exposure to predatory risk in nursery areas vary. According to Branstetter hypothesis, slow growing species are either born at relatively large sizes or use protected nursery grounds, whereas faster growing species tend to rely more on growth rates than others factors. Primary nurseries are habitats where parturition occurs and in which the young live for a short time and secondary nurseries are habitats in which juveniles are found after leaving the primary nursery and before reaching maturity. Rhizoprionodon porosus and Carcharhinus acronotus use coastal waters off Cai?ara do Norte as both primary and secondary nurseries, while Carcharhinus limbatus makes use of the area as a seasonal primary nursery in late spring and early summer. C. falciformis apparently makes use of the end of inner continental shelf and the outer continental shelf as a primary nursery. Gymnura micrura, Rhinobatos percellens and Narcine brasiliensis makes use of coastal and turbid waters of region as both primary and secondary nurseries throughout the year, while Dasyatis guttata utilizes the area as a primary nursery. Aetobatus narinari and Rhinoptera bonasus, although caught in lesser number, appear to use the region as both primary and secondary nurseries and only primary nursery respectively. Dasyatis marianae (endemic from Northeastern Brazil) may use coastal sandbanks as a primary nursery, while Dasyatis Americana apparently exploits waters about 10 – 20 m in depth with rocky reef substrate only as secondary nursery. There was a measurable degree of temporal and spatial separation among sharks’ species, which may effectively create separate ecological niches, whereas among rays, with the exception of the stingray D. marianae, a spatial and temporal overlaps were observed. The Branstetter’s hypothesis was supported.     

New findings of <Emphasis Type="Italic">Lophius litulon</Emphasis> (Lophiidae) off the Southern Kurils

Data on new captures of juveniles of the yellow anglerfish Lophius litulon off the Southern Kurils are presented. Outer morphological characters of the specimens caught in waters off the Southern Kurils are described in comparison with those of specimens from other regions of the north-western part of the Pacific Ocean. Probable pathways of penetration of anglerfish (Lophiidae) to Russian Far East waters are discussed.     

Sulfate control of phosphorus availability in lakes

During summer stratification large amounts of phosphorus (P) accumulate in anoxic bottom waters of many lakes due to release of P from underlying sediments. The availability to phytoplankton of this P is inversely related to the Fe:P ratio in bottom waters. Using data from 51 lakes, we tested the hypothesis that sulfate concentration in lake water may be critical in controlling the Fe:P ratio in anoxic bottom waters. Results showed that Fe:P ratios in bottom waters of lakes were significantly (p<0.001) related to surface water sulfate concentrations. The higher Fe:P ratios in low sulfate systems is due not only to higher iron concentrations in anoxic bottom waters but also to lower P concentrations in anoxic waters. Thus, our results suggest that anthropogenically induced increases in sulfate concentrations of waters (e.g. from fossil fuel burning) may have a double effect on P cycling in lakes. Higher sulfate concentrations can both increase the magnitude of P release from sediments as well as increase the availability of P released from sediments into anoxic bottom waters.