Avian reproduction is a process that requires extensive energetic input by parents, particularly in pelagic seabirds. Parental infanticide has rarely been reported in pelagic seabirds, and its frequency among taxa is therefore difficult to determine. Using data from remote cameras, two cases of probable parental infanticide in Red-billed Tropicbirds Phaethon aethereus were captured on Sint Eustatius in the 2021–2022 breeding season. Both cases are presented with images collected from remote cameras as evidence. While appearing counterproductive, parental infanticide may provide an alternative reproduction strategy that favors lifetime reproductive success over short term success.
The queen conch (Strombus gigas) is a large economically important gastropod that has been severely depleted throughout much of the Caribbean region. The species has determinate growth and reaches maximum shell length before sexual maturation; thereafter the shell grows only in thickness. In this study, queen conch were collected in the Exuma Cays, Bahamas, to evaluate maturity with respect to shell length (SL) (170–255 mm) and shell lip thickness (LT) (2–42 mm). Soft tissue weight and gonad weight increased with SL, but these same variables, along with the gonadosomatic index (gonad weight/soft tissue weight), all had dome-shaped distributions with LT and decreased slightly with LT > 22 mm. This indicates some loss of fecundity with age; however, no loss of reproductive capability was evident in histological data. Gonad maturity lagged substantially behind first formation of the shell lip. Minimum LT for reproductive maturity was 12 mm for females and 9 mm for males, and 50% maturity for the population was achieved at 26 mm LT for females and 24 mm LT for males, higher than previous estimates. A review of fishing regulations indicates that immature queen conch are being harvested legally in most Caribbean nations, providing at least a partial explanation for widespread depletion. While relationships between shell lip thickness, age, and maturity vary geographically, sustainable management of queen conch will require a minimum shell lip thickness for harvest no less than 15 mm, along with other urgently needed management measures.
ABSTRACT: Effectiveness of a marine protected area (MPA) in supporting fisheries productivity depends upon replenishment patterns, both in supplying recruits to surrounding fished areas and having a sustainable spawning stock in the MPA. Surveys for queen conch Strombus gigas were made in 2011 at 2 locations in the Exuma Cays, The Bahamas, for direct comparison with surveys conducted during the early 1990s at Warderick Wells (WW) near the center of the Exuma Cays Land and Sea Park (ECLSP) and at a fished site near Lee Stocking Island (LSI). There was no change in adult conch density and abundance in the shallow bank environment at LSI where numbers were already low in 1991, but numbers declined 91% in the deeper shelf waters. At WW, the adult population declined 69% on the bank and 6% on the island shelf. Unlike observations made in the 1990s, queen conch reproductive behavior near LSI is now rare. Average age of adult conch (indicated by shell thickness) at LSI decreased significantly during the 20 yr period between surveys, while average age increased at WW and juvenile abundance decreased. These results show that the LSI population is being overfished and the WW population is senescing because of low recruitment. In 2011, the ECLSP continued to be an important source of larvae for down- stream populations because of abundant spawners in the shelf environment. However, it is clear that the reserve is not self-sustaining for queen conch, and sustainable fishing in the Exuma Cays will depend upon a network of MPAs along with other management measures to reduce fishing mortality.
This study investigated the reproductive behavior of the Caribbean Sergeant Major, Abudefduf saxatilis. The aim was to identify the possible relationships between nest locations, brood size and aggression rates in males when guarding their eggs. Surveys were conducted using Sergeant Major nesting aggregations located on a group of 5m deep mooring blocks on Bonaire, Netherlands Antilles. As brood size increased, aggression rates (attacks/ min) also significantly increased (R2 = 0.0492). The benefits of protecting the brood from intruders may outweigh the risks to the individual for large broods. Aggressiveness can also be a behavioral trait preferred by females when choosing a nest to lay their eggs. Therefore males who exhibit greater aggression may be more reproductively successful. Aggression rates significantly increased for individuals nesting on or near the upper level on the mooring blocks (t= 0.00045; p<0.05). Although the number of other fish visiting the different areas of the mooring blocks was not counted, the general impression was that the upper portions of the blocks were subject to more traffic from other fish. The helps support the finding that aggression rates increased for nests located in the higher positions because these males may have been given more opportunity to defend their eggs. No significant relationship was found between nest location and brood size. Nest location did not appear to be important in determining patterns of female egg-laying suggesting that male choice, rather than nest choice is the driving factor.
This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 31-35 from CIEE Bonaire.
Nesting animals select sites for reproduction based on adaptive behaviors that have evolved to improve reproductive success and the survival rates of offspring. Abudefduf saxatilis, commonly known as the sergeant major, is a pomacentrid fish that exhibits nesting and nest-guarding behaviors. This study in the coastal waters of Bonaire, Dutch Caribbean, evaluates whether A. saxatilis selects rough or smooth substrates for nesting, and whether there is a vertical relief requirement for the nesting site using a reef survey and a field experiment. Nests on the reef were surveyed to determine if trends exist in the number and area of nests as height and rugosity of substrates increase, and a field experiment was designed to present the fish with a choice between rough or smooth surfaces and between units of varying heights. It was hypothesized that A. saxatilis would lay more and larger nests on smooth substrates with a vertical relief >20cm in both the experimental and reef environments. A trend towards more nests on smoother surfaces was observed in both the block experiment and in the reef survey, but no trends in number or area of nests were consistent between the experiment and the reef survey. Understanding the patterns of nest selection of A. saxatilis will provide important insight into the reproductive success of this highly abundant species, and because availability of nesting sites is a bottom-up control that can influence coral reef trophic structures.
This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 12-19 from CIEE Bonaire.
Sergeant majors (Abudefduf saxatilis) engage in male-dominated reproduction: males establish territories, females are courted, mate with the male and then depart – leaving protection of the eggs to the male. A. saxatilis prefer smooth, artificial substrate for egg laying; in Bonaire, Dutch Caribbean, they tend to mate on large, concrete mooring blocks which have surfaces of varying degrees of exposure to the water column. Preferred nesting locations were expected to be those offering the least exposure, as broods would be shielded from predators and guarding males would expend minimal energy. The number of threats, chases and feeds in a 5 min interval were recorded as an indicator of energy expenditure and consumption. The length of the fish and size of corresponding egg brood were measured as indicators of mating potential. The number of threats, chases and feeds did not differ significantly between degrees of exposure, but threats and chases differed between sites, being greatest at the site closest to the reef, possibly indicating that exposure does not play a role in energy expenditure and therefore may not affect preferred mating locations. However, larger fish and larger broods were observed on the most protected sides of the mooring blocks offering some support to the notion that A. saxatilis prefer to nest in more protected locations. An increase in the number of artificial structures could lead to an A. saxatilis population rise
Bicolor damselfish, Stegastes partitus, are well known for their aggressive nature. They are known to attack almost any species threatening their food, territory or spawn, often regardless of the size of the intruder. Studies show that three spot damselfish are even able to identify certain species based on the threat they present by displaying different aggressive behaviors. However, little is known on how, and if, these aggressive displays are species dependent in bicolors. The purpose of this study was to test for species dependent aggression in bicolor damselfish during reproductive season to determine if this behavior relates to increased egg protection during reproductive season. Four damselfish individuals were analyzed over the course of five weeks during one reproductive and one non-reproductive cycle using underwater video camcorders. S. partitus was shown to increase frequency of aggression toward egg threatening intruders while guarding eggs. Conversely, they were shown to decrease in frequency of aggression towards intruders threatening their food resources. Lastly, the frequency of intrusion for eggeating intruders was not shown to significantly increase while bicolor damselfish eggs were present.
This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 9-14 from CIEE Bonaire.
Two bat species, Leptonyrteris curasoae and Glossophaga longirostris, are the principal pollinators of at least two of the three species of columnar cacti that grow on the semiarid island of Curaçao, Netherlands Antilles. I examined the importance of the cacti in the diets of the bats and found that 85–91 percent of their diet samples contained cactus pollen and seeds. At least 43 percent of the samples from each species contained cactus pollen andlor seeds exclusively. Leptonycteris curasoae consumes nectar and pollen of Ceiba pentandra and Agave spp. at the beginning of the dry season and G. longirostris also consumes a few other plant products in the wet season, but both bat species depend nutritionally on cacti. Female bats give birth to one pup per year, and the periods of parturition and lactation in each species correspond to peaks in the reproductive phenology of the two most abundant columnar cactus species. From personal observations and a review of the literature, I determined that bats were unlikely to fly to the mainland to feed, although L. curasoae may do so. I conclude that the interdependence of bats and cacti is suggestive of coevolution, and that columnar cacti are critical for the survival and persistence of nectar-feeding bats on Curaçao.
The ecology of common snook Centropomus undecimalis in Amatique Bay, a tropical estuary in eastern Guatemala, was investigated and life-history traits were used to conduct a meta-analysis of the species from Florida to Brazil. The reproduction cycle of C. undecimalis in Amatique was strongly related to the precipitation cycle, with a lag of 2months. Spawning occurred from April to November with a peak spawning after the onset of the summer rains. Protandric sex reversal occurred early in the dry season (December) before somatic recovery from spawning. The growth cycle preceded that of body condition by c. 1month, and was out of phase with the reproductive cycle. Growth was fast, as many individuals reached >70% of the maximum observed total length (LT, 102cm) after 3years. Sex transition occurred within a relatively narrow LT range (70–79cm), but over a wide range of ages, indicating plasticity in this respect. The meta-analysis indicated a latitudinal-temperature gradient in life-history traits, as well as different seasonal patterns relative to temperature and hydrographical cycles. Centropomus undecimalis from cooler winter waters (e.g. Florida) reach larger maximum LT and LT at sex change, as well as greater gonado-somatic indices and longer life spans. Further, increased fishing mortality results in younger age at sex reversal and male predominance in the populations compared. Recognition of large-scale biogeographic patterns in this important, but little studied, fish species helps in the formulation of management advice in other areas of its occurrence.