Publications by authors named "Matthew J Ajemian"

The Indian River Lagoon is a primary location of field-based "grow-out" for bivalve shellfish aquaculture along Florida's Atlantic coast. Grow-out locations have substantially higher clam densities than surrounding ambient sediment, potentially attracting mollusk predators to the area. Inspired by clammer reports of damaged grow-out gear, we used passive acoustic telemetry to examine the potential interactions between two highly mobile invertivores-whitespotted eagle rays (Aetobatus narinari) and cownose rays (Rhinoptera spp.

View Article and Find Full Text PDF

The goal of this paper is to implement and deploy an automated detector and localization model to locate underwater marine organisms using their low-frequency pulse sounds. This model is based on time difference of arrival (TDOA) and uses a two-stage approach, first, to identify the sound and, second, to localize it. In the first stage, an adaptive matched filter (MF) is designed and implemented to detect and determine the timing of the sound pulses recorded by the hydrophones.

View Article and Find Full Text PDF

Florida's Indian River Lagoon (IRL) has experienced large-scale, frequent blooms of toxic harmful algae in recent decades. Sentinel, or indicator, species can provide an integrated picture of contaminants in the environment and may be useful to understanding phycotoxin prevalence in the IRL. This study evaluated the presence of phycotoxins in the IRL ecosystem by using the bull shark (Carcharhinus leucas) as a sentinel species.

View Article and Find Full Text PDF

Biophysical models are a powerful tool for assessing population connectivity of marine organisms that broadcast spawn. Albula vulpes is a species of bonefish that is an economically and culturally important sportfish found throughout the Caribbean and that exhibits genetic connectivity among geographically distant populations. We created ontogenetically relevant biophysical models for bonefish larval dispersal based upon multiple observed spawning events in Abaco, The Bahamas in 2013, 2018, and 2019.

View Article and Find Full Text PDF

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species.

View Article and Find Full Text PDF

Offshore platforms, subsea pipelines, wells and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. Although structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes remains unclear. Here, we review the current state of knowledge on the role of O&G infrastructure in maintaining, altering or enhancing ecological connectivity with natural marine habitats.

View Article and Find Full Text PDF

Inertial measurement unit sensors (IMU; i.e., accelerometer, gyroscope and magnetometer combinations) are frequently fitted to animals to better understand their activity patterns and energy expenditure.

View Article and Find Full Text PDF

We report 24 new records of the Brazilian cownose ray Rhinoptera brasiliensis outside its accepted geographic range. Sequencing of a 442-base pair portion of the mitochondrial NADH dehydrogenase subunit 2 gene for 282 Rhinoptera samples revealed eight records off the east coast of the USA and 16 from the eastern Gulf of Mexico. Both sexes of all life stages were documented in all seasons over multiple years in the Indian River and Lake Worth lagoons, Florida, indicating that their range extends further in the western North Atlantic than previously described.

View Article and Find Full Text PDF

The whitespotted eagle ray Aetobatus narinari is a tropical to warm-temperate benthopelagic batoid that ranges widely throughout the western Atlantic Ocean. Despite conservation concerns for the species, its vertical habitat use and diving behaviour remain unknown. Patterns and drivers in the depth distribution of A.

View Article and Find Full Text PDF

The tiger shark (Galeocerdo cuvier) is globally distributed with established coastal and open-ocean movement patterns in many portions of its range. While all life stages of tiger sharks are known to occur in the Gulf of Mexico (GoM), variability in habitat use and movement patterns over ontogeny have never been quantified in this large marine ecosystem. To address this data gap we fitted 56 tiger sharks with Smart Position and Temperature transmitting tags between 2010 and 2018 and examined seasonal and spatial distribution patterns across the GoM.

View Article and Find Full Text PDF

Numerous toxin-producing harmful algal (HAB) species occur in Florida's coastal waters. Exposure to these toxins has been shown to have sublethal effects in sea turtles. The objective of this study was to establish concentrations of 10 HAB toxins in plasma samples from green turtles () foraging in Florida's Big Bend.

View Article and Find Full Text PDF

Bonefishes (Albula spp.) are classified within the superorder Elopomorpha, which is comprised of over 1000 species that share a unique leptocephalus larval stage. Bonefishes have a circum-tropical distribution, inhabiting inshore shallow water flats and gathering in presumptive nearshore pre-spawn aggregations (PSA) during spawning months.

View Article and Find Full Text PDF

Two different methods, metagenetics and free-otolith identification, were used to identify prey in the stomach contents of 531 Gymnura lessae captured by trawling in Mobile Bay, Alabama 2016-2018. Both methods were found to produce analogous results and were therefore combined into a single complete dataset. All prey were teleosts; the families Sciaenidae and Engraulidae were the most important prey (prey specie index of relative importance 89.

View Article and Find Full Text PDF

The timing and extent of international crossings by billfishes, tunas, and sharks in the Cuba-Mexico-United States (U.S.) triangle was investigated using electronic tagging data from eight species that resulted in >22,000 tracking days.

View Article and Find Full Text PDF

In recent years, white sharks (Carcharodon carcharias) have become more accessible to researchers off the northeastern U.S. as feeding aggregation sites have emerged and the population has increased.

View Article and Find Full Text PDF

Artificial structures are the dominant complex marine habitat type along the northwestern Gulf of Mexico (GOM) shelf. These habitats can consist of a variety of materials, but in this region are primarily comprised of active and reefed oil and gas platforms. Despite being established for several decades, the fish communities inhabiting these structures remain poorly investigated.

View Article and Find Full Text PDF

Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas), habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sharks in Mobile Bay, Alabama, thirty-five sharks were fitted with internal acoustic transmitters and monitored with an acoustic monitoring array consisting of thirty-three receivers between June 2009 and December 2010.

View Article and Find Full Text PDF

Declines of large sharks and subsequent release of elasmobranch mesopredators (smaller sharks and rays) may pose problems for marine fisheries management as some mesopredators consume exploitable shellfish species. The spotted eagle ray (Aetobatus narinari) is the most abundant inshore elasmobranch in subtropical Bermuda, but its predatory role remains unexamined despite suspected abundance increases and its hypothesized specialization for mollusks. We utilized a combination of acoustic telemetry, benthic invertebrate sampling, gut content analysis and manipulative experiments to assess the impact of spotted eagle rays on Bermudian shellfish resources.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_sessiondpkkuqc308chu2oun042ea1jdfqhosqm): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once